1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
// This file is part of Tetcore.

// Copyright (C) 2019-2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Traits for FABRIC.
//!
//! NOTE: If you're looking for `parameter_types`, it has moved in to the top-level module.

use tetcore_std::{prelude::*, result, marker::PhantomData, ops::Div, fmt::Debug};
use codec::{FullCodec, Codec, Encode, Decode, EncodeLike};
use tet_core::u32_trait::Value as U32;
use tp_runtime::{
	RuntimeDebug, ConsensusEngineId, DispatchResult, DispatchError,
	traits::{
		MaybeSerializeDeserialize, AtLeast32Bit, Saturating, TrailingZeroInput, Bounded, Zero,
		BadOrigin, AtLeast32BitUnsigned, UniqueSaturatedFrom, UniqueSaturatedInto,
		SaturatedConversion, StoredMapError,
	},
};
use crate::dispatch::Parameter;
use crate::storage::StorageMap;
use crate::weights::Weight;
use bitflags::bitflags;
use impl_trait_for_tuples::impl_for_tuples;

/// Re-expected for the macro.
#[doc(hidden)]
pub use tetcore_std::{mem::{swap, take}, cell::RefCell, vec::Vec, boxed::Box};

/// Simple trait for providing a filter over a reference to some type.
pub trait Filter<T> {
	/// Determine if a given value should be allowed through the filter (returns `true`) or not.
	fn filter(_: &T) -> bool;
}

impl<T> Filter<T> for () {
	fn filter(_: &T) -> bool { true }
}

/// Trait to add a constraint onto the filter.
pub trait FilterStack<T>: Filter<T> {
	/// The type used to archive the stack.
	type Stack;

	/// Add a new `constraint` onto the filter.
	fn push(constraint: impl Fn(&T) -> bool + 'static);

	/// Removes the most recently pushed, and not-yet-popped, constraint from the filter.
	fn pop();

	/// Clear the filter, returning a value that may be used later to `restore` it.
	fn take() -> Self::Stack;

	/// Restore the filter from a previous `take` operation.
	fn restore(taken: Self::Stack);
}

/// Guard type for pushing a constraint to a `FilterStack` and popping when dropped.
pub struct FilterStackGuard<F: FilterStack<T>, T>(PhantomData<(F, T)>);

/// Guard type for clearing all pushed constraints from a `FilterStack` and reinstating them when
/// dropped.
pub struct ClearFilterGuard<F: FilterStack<T>, T>(Option<F::Stack>, PhantomData<T>);

impl<F: FilterStack<T>, T> FilterStackGuard<F, T> {
	/// Create a new instance, adding a new `constraint` onto the filter `T`, and popping it when
	/// this instance is dropped.
	pub fn new(constraint: impl Fn(&T) -> bool + 'static) -> Self {
		F::push(constraint);
		Self(PhantomData)
	}
}

impl<F: FilterStack<T>, T> Drop for FilterStackGuard<F, T> {
	fn drop(&mut self) {
		F::pop();
	}
}

impl<F: FilterStack<T>, T> ClearFilterGuard<F, T> {
	/// Create a new instance, adding a new `constraint` onto the filter `T`, and popping it when
	/// this instance is dropped.
	pub fn new() -> Self {
		Self(Some(F::take()), PhantomData)
	}
}

impl<F: FilterStack<T>, T> Drop for ClearFilterGuard<F, T> {
	fn drop(&mut self) {
		if let Some(taken) = self.0.take() {
			F::restore(taken);
		}
	}
}

/// Simple trait for providing a filter over a reference to some type, given an instance of itself.
pub trait InstanceFilter<T>: Sized + Send + Sync {
	/// Determine if a given value should be allowed through the filter (returns `true`) or not.
	fn filter(&self, _: &T) -> bool;

	/// Determines whether `self` matches at least everything that `_o` does.
	fn is_superset(&self, _o: &Self) -> bool { false }
}

impl<T> InstanceFilter<T> for () {
	fn filter(&self, _: &T) -> bool { true }
	fn is_superset(&self, _o: &Self) -> bool { true }
}

#[macro_export]
macro_rules! impl_filter_stack {
	($target:ty, $base:ty, $call:ty, $module:ident) => {
		#[cfg(feature = "std")]
		mod $module {
			#[allow(unused_imports)]
			use super::*;
			use $crate::traits::{swap, take, RefCell, Vec, Box, Filter, FilterStack};

			thread_local! {
				static FILTER: RefCell<Vec<Box<dyn Fn(&$call) -> bool + 'static>>> = RefCell::new(Vec::new());
			}

			impl Filter<$call> for $target {
				fn filter(call: &$call) -> bool {
					<$base>::filter(call) &&
						FILTER.with(|filter| filter.borrow().iter().all(|f| f(call)))
				}
			}

			impl FilterStack<$call> for $target {
				type Stack = Vec<Box<dyn Fn(&$call) -> bool + 'static>>;
				fn push(f: impl Fn(&$call) -> bool + 'static) {
					FILTER.with(|filter| filter.borrow_mut().push(Box::new(f)));
				}
				fn pop() {
					FILTER.with(|filter| filter.borrow_mut().pop());
				}
				fn take() -> Self::Stack {
					FILTER.with(|filter| take(filter.borrow_mut().as_mut()))
				}
				fn restore(mut s: Self::Stack) {
					FILTER.with(|filter| swap(filter.borrow_mut().as_mut(), &mut s));
				}
			}
		}

		#[cfg(not(feature = "std"))]
		mod $module {
			#[allow(unused_imports)]
			use super::*;
			use $crate::traits::{swap, take, RefCell, Vec, Box, Filter, FilterStack};

			struct ThisFilter(RefCell<Vec<Box<dyn Fn(&$call) -> bool + 'static>>>);
			// NOTE: Safe only in wasm (guarded above) because there's only one thread.
			unsafe impl Send for ThisFilter {}
			unsafe impl Sync for ThisFilter {}

			static FILTER: ThisFilter = ThisFilter(RefCell::new(Vec::new()));

			impl Filter<$call> for $target {
				fn filter(call: &$call) -> bool {
					<$base>::filter(call) && FILTER.0.borrow().iter().all(|f| f(call))
				}
			}

			impl FilterStack<$call> for $target {
				type Stack = Vec<Box<dyn Fn(&$call) -> bool + 'static>>;
				fn push(f: impl Fn(&$call) -> bool + 'static) {
					FILTER.0.borrow_mut().push(Box::new(f));
				}
				fn pop() {
					FILTER.0.borrow_mut().pop();
				}
				fn take() -> Self::Stack {
					take(FILTER.0.borrow_mut().as_mut())
				}
				fn restore(mut s: Self::Stack) {
					swap(FILTER.0.borrow_mut().as_mut(), &mut s);
				}
			}
		}
	}
}

/// Type that provide some integrity tests.
///
/// This implemented for modules by `decl_module`.
#[impl_for_tuples(30)]
pub trait IntegrityTest {
	/// Run integrity test.
	///
	/// The test is not executed in a externalities provided environment.
	fn integrity_test() {}
}

#[cfg(test)]
mod test_impl_filter_stack {
	use super::*;

	pub struct IsCallable;
	pub struct BaseFilter;
	impl Filter<u32> for BaseFilter {
		fn filter(x: &u32) -> bool { x % 2 == 0 }
	}
	impl_filter_stack!(
		crate::traits::test_impl_filter_stack::IsCallable,
		crate::traits::test_impl_filter_stack::BaseFilter,
		u32,
		is_callable
	);

	#[test]
	fn impl_filter_stack_should_work() {
		assert!(IsCallable::filter(&36));
		assert!(IsCallable::filter(&40));
		assert!(IsCallable::filter(&42));
		assert!(!IsCallable::filter(&43));

		IsCallable::push(|x| *x < 42);
		assert!(IsCallable::filter(&36));
		assert!(IsCallable::filter(&40));
		assert!(!IsCallable::filter(&42));

		IsCallable::push(|x| *x % 3 == 0);
		assert!(IsCallable::filter(&36));
		assert!(!IsCallable::filter(&40));

		IsCallable::pop();
		assert!(IsCallable::filter(&36));
		assert!(IsCallable::filter(&40));
		assert!(!IsCallable::filter(&42));

		let saved = IsCallable::take();
		assert!(IsCallable::filter(&36));
		assert!(IsCallable::filter(&40));
		assert!(IsCallable::filter(&42));
		assert!(!IsCallable::filter(&43));

		IsCallable::restore(saved);
		assert!(IsCallable::filter(&36));
		assert!(IsCallable::filter(&40));
		assert!(!IsCallable::filter(&42));

		IsCallable::pop();
		assert!(IsCallable::filter(&36));
		assert!(IsCallable::filter(&40));
		assert!(IsCallable::filter(&42));
		assert!(!IsCallable::filter(&43));
	}

	#[test]
	fn guards_should_work() {
		assert!(IsCallable::filter(&36));
		assert!(IsCallable::filter(&40));
		assert!(IsCallable::filter(&42));
		assert!(!IsCallable::filter(&43));
		{
			let _guard_1 = FilterStackGuard::<IsCallable, u32>::new(|x| *x < 42);
			assert!(IsCallable::filter(&36));
			assert!(IsCallable::filter(&40));
			assert!(!IsCallable::filter(&42));
			{
				let _guard_2 = FilterStackGuard::<IsCallable, u32>::new(|x| *x % 3 == 0);
				assert!(IsCallable::filter(&36));
				assert!(!IsCallable::filter(&40));
			}
			assert!(IsCallable::filter(&36));
			assert!(IsCallable::filter(&40));
			assert!(!IsCallable::filter(&42));
			{
				let _guard_2 = ClearFilterGuard::<IsCallable, u32>::new();
				assert!(IsCallable::filter(&36));
				assert!(IsCallable::filter(&40));
				assert!(IsCallable::filter(&42));
				assert!(!IsCallable::filter(&43));
			}
			assert!(IsCallable::filter(&36));
			assert!(IsCallable::filter(&40));
			assert!(!IsCallable::filter(&42));
		}
		assert!(IsCallable::filter(&36));
		assert!(IsCallable::filter(&40));
		assert!(IsCallable::filter(&42));
		assert!(!IsCallable::filter(&43));
	}
}

/// An abstraction of a value stored within storage, but possibly as part of a larger composite
/// item.
pub trait StoredMap<K, T: Default> {
	/// Get the item, or its default if it doesn't yet exist; we make no distinction between the
	/// two.
	fn get(k: &K) -> T;

	/// Maybe mutate the item only if an `Ok` value is returned from `f`. Do nothing if an `Err` is
	/// returned. It is removed or reset to default value if it has been mutated to `None`
	fn try_mutate_exists<R, E: From<StoredMapError>>(
		k: &K,
		f: impl FnOnce(&mut Option<T>) -> Result<R, E>,
	) -> Result<R, E>;

	// Everything past here has a default implementation.

	/// Mutate the item.
	fn mutate<R>(k: &K, f: impl FnOnce(&mut T) -> R) -> Result<R, StoredMapError> {
		Self::mutate_exists(k, |maybe_account| match maybe_account {
			Some(ref mut account) => f(account),
			x @ None => {
				let mut account = Default::default();
				let r = f(&mut account);
				*x = Some(account);
				r
			}
		})
	}

	/// Mutate the item, removing or resetting to default value if it has been mutated to `None`.
	///
	/// This is infallible as long as the value does not get destroyed.
	fn mutate_exists<R>(
		k: &K,
		f: impl FnOnce(&mut Option<T>) -> R,
	) -> Result<R, StoredMapError> {
		Self::try_mutate_exists(k, |x| -> Result<R, StoredMapError> { Ok(f(x)) })
	}

	/// Set the item to something new.
	fn insert(k: &K, t: T) -> Result<(), StoredMapError> { Self::mutate(k, |i| *i = t) }

	/// Remove the item or otherwise replace it with its default value; we don't care which.
	fn remove(k: &K) -> Result<(), StoredMapError> { Self::mutate_exists(k, |x| *x = None) }
}

/// A simple, generic one-parameter event notifier/handler.
pub trait HandleLifetime<T> {
	/// An account was created.
	fn created(_t: &T) -> Result<(), StoredMapError> { Ok(()) }

	/// An account was killed.
	fn killed(_t: &T) -> Result<(), StoredMapError> { Ok(()) }
}

impl<T> HandleLifetime<T> for () {}

/// A shim for placing around a storage item in order to use it as a `StoredValue`. Ideally this
/// wouldn't be needed as `StorageValue`s should blanket implement `StoredValue`s, however this
/// would break the ability to have custom impls of `StoredValue`. The other workaround is to
/// implement it directly in the macro.
///
/// This form has the advantage that two additional types are provides, `Created` and `Removed`,
/// which are both generic events that can be tied to handlers to do something in the case of being
/// about to create an account where one didn't previously exist (at all; not just where it used to
/// be the default value), or where the account is being removed or reset back to the default value
/// where previously it did exist (though may have been in a default state). This works well with
/// system module's `CallOnCreatedAccount` and `CallKillAccount`.
pub struct StorageMapShim<S, L, K, T>(tetcore_std::marker::PhantomData<(S, L, K, T)>);
impl<
	S: StorageMap<K, T, Query=T>,
	L: HandleLifetime<K>,
	K: FullCodec,
	T: FullCodec + Default,
> StoredMap<K, T> for StorageMapShim<S, L, K, T> {
	fn get(k: &K) -> T { S::get(k) }
	fn insert(k: &K, t: T) -> Result<(), StoredMapError> {
		if !S::contains_key(&k) {
			L::created(k)?;
		}
		S::insert(k, t);
		Ok(())
	}
	fn remove(k: &K) -> Result<(), StoredMapError> {
		if S::contains_key(&k) {
			L::killed(&k)?;
			S::remove(k);
		}
		Ok(())
	}
	fn mutate<R>(k: &K, f: impl FnOnce(&mut T) -> R) -> Result<R, StoredMapError> {
		if !S::contains_key(&k) {
			L::created(k)?;
		}
		Ok(S::mutate(k, f))
	}
	fn mutate_exists<R>(k: &K, f: impl FnOnce(&mut Option<T>) -> R) -> Result<R, StoredMapError> {
		S::try_mutate_exists(k, |maybe_value| {
			let existed = maybe_value.is_some();
			let r = f(maybe_value);
			let exists = maybe_value.is_some();

			if !existed && exists {
				L::created(k)?;
			} else if existed && !exists {
				L::killed(k)?;
			}
			Ok(r)
		})
	}
	fn try_mutate_exists<R, E: From<StoredMapError>>(
		k: &K,
		f: impl FnOnce(&mut Option<T>) -> Result<R, E>,
	) -> Result<R, E> {
		S::try_mutate_exists(k, |maybe_value| {
			let existed = maybe_value.is_some();
			let r = f(maybe_value)?;
			let exists = maybe_value.is_some();

			if !existed && exists {
				L::created(k).map_err(E::from)?;
			} else if existed && !exists {
				L::killed(k).map_err(E::from)?;
			}
			Ok(r)
		})
	}
}

/// Something that can estimate at which block the next session rotation will happen. This should
/// be the same logical unit that dictates `ShouldEndSession` to the session module. No Assumptions
/// are made about the scheduling of the sessions.
pub trait EstimateNextSessionRotation<BlockNumber> {
	/// Return the block number at which the next session rotation is estimated to happen.
	///
	/// None should be returned if the estimation fails to come to an answer
	fn estimate_next_session_rotation(now: BlockNumber) -> Option<BlockNumber>;

	/// Return the weight of calling `estimate_next_session_rotation`
	fn weight(now: BlockNumber) -> Weight;
}

impl<BlockNumber: Bounded> EstimateNextSessionRotation<BlockNumber> for () {
	fn estimate_next_session_rotation(_: BlockNumber) -> Option<BlockNumber> {
		Default::default()
	}

	fn weight(_: BlockNumber) -> Weight {
		0
	}
}

/// Something that can estimate at which block the next `new_session` will be triggered. This must
/// always be implemented by the session module.
pub trait EstimateNextNewSession<BlockNumber> {
	/// Return the block number at which the next new session is estimated to happen.
	fn estimate_next_new_session(now: BlockNumber) -> Option<BlockNumber>;

	/// Return the weight of calling `estimate_next_new_session`
	fn weight(now: BlockNumber) -> Weight;
}

impl<BlockNumber: Bounded> EstimateNextNewSession<BlockNumber> for () {
	fn estimate_next_new_session(_: BlockNumber) -> Option<BlockNumber> {
		Default::default()
	}

	fn weight(_: BlockNumber) -> Weight {
		0
	}
}

/// Anything that can have a `::len()` method.
pub trait Len {
	/// Return the length of data type.
	fn len(&self) -> usize;
}

impl<T: IntoIterator + Clone,> Len for T where <T as IntoIterator>::IntoIter: ExactSizeIterator {
	fn len(&self) -> usize {
		self.clone().into_iter().len()
	}
}

/// A trait for querying a single value from a type.
///
/// It is not required that the value is constant.
pub trait Get<T> {
	/// Return the current value.
	fn get() -> T;
}

impl<T: Default> Get<T> for () {
	fn get() -> T { T::default() }
}

/// A trait for querying whether a type can be said to "contain" a value.
pub trait Contains<T: Ord> {
	/// Return `true` if this "contains" the given value `t`.
	fn contains(t: &T) -> bool { Self::sorted_members().binary_search(t).is_ok() }

	/// Get a vector of all members in the set, ordered.
	fn sorted_members() -> Vec<T>;

	/// Get the number of items in the set.
	fn count() -> usize { Self::sorted_members().len() }

	/// Add an item that would satisfy `contains`. It does not make sure any other
	/// state is correctly maintained or generated.
	///
	/// **Should be used for benchmarking only!!!**
	#[cfg(feature = "runtime-benchmarks")]
	fn add(_t: &T) { unimplemented!() }
}

/// A trait for querying bound for the length of an implementation of `Contains`
pub trait ContainsLengthBound {
	/// Minimum number of elements contained
	fn min_len() -> usize;
	/// Maximum number of elements contained
	fn max_len() -> usize;
}

/// Handler for when a new account has been created.
#[impl_for_tuples(30)]
pub trait OnNewAccount<AccountId> {
	/// A new account `who` has been registered.
	fn on_new_account(who: &AccountId);
}

/// The account with the given id was reaped.
#[impl_for_tuples(30)]
pub trait OnKilledAccount<AccountId> {
	/// The account with the given id was reaped.
	fn on_killed_account(who: &AccountId);
}

/// A trait for finding the author of a block header based on the `PreRuntime` digests contained
/// within it.
pub trait FindAuthor<Author> {
	/// Find the author of a block based on the pre-runtime digests.
	fn find_author<'a, I>(digests: I) -> Option<Author>
		where I: 'a + IntoIterator<Item=(ConsensusEngineId, &'a [u8])>;
}

impl<A> FindAuthor<A> for () {
	fn find_author<'a, I>(_: I) -> Option<A>
		where I: 'a + IntoIterator<Item=(ConsensusEngineId, &'a [u8])>
	{
		None
	}
}

/// A trait for verifying the seal of a header and returning the author.
pub trait VerifySeal<Header, Author> {
	/// Verify a header and return the author, if any.
	fn verify_seal(header: &Header) -> Result<Option<Author>, &'static str>;
}

/// Something which can compute and check proofs of
/// a historical key owner and return full identification data of that
/// key owner.
pub trait KeyOwnerProofSystem<Key> {
	/// The proof of membership itself.
	type Proof: Codec;
	/// The full identification of a key owner and the stash account.
	type IdentificationTuple: Codec;

	/// Prove membership of a key owner in the current block-state.
	///
	/// This should typically only be called off-chain, since it may be
	/// computationally heavy.
	///
	/// Returns `Some` iff the key owner referred to by the given `key` is a
	/// member of the current set.
	fn prove(key: Key) -> Option<Self::Proof>;

	/// Check a proof of membership on-chain. Return `Some` iff the proof is
	/// valid and recent enough to check.
	fn check_proof(key: Key, proof: Self::Proof) -> Option<Self::IdentificationTuple>;
}

impl<Key> KeyOwnerProofSystem<Key> for () {
	// The proof and identification tuples is any bottom type to guarantee that the methods of this
	// implementation can never be called or return anything other than `None`.
	type Proof = crate::Void;
	type IdentificationTuple = crate::Void;

	fn prove(_key: Key) -> Option<Self::Proof> {
		None
	}

	fn check_proof(_key: Key, _proof: Self::Proof) -> Option<Self::IdentificationTuple> {
		None
	}
}

/// Handler for when some currency "account" decreased in balance for
/// some reason.
///
/// The only reason at present for an increase would be for validator rewards, but
/// there may be other reasons in the future or for other chains.
///
/// Reasons for decreases include:
///
/// - Someone got slashed.
/// - Someone paid for a transaction to be included.
pub trait OnUnbalanced<Imbalance: TryDrop> {
	/// Handler for some imbalances. The different imbalances might have different origins or
	/// meanings, dependent on the context. Will default to simply calling on_unbalanced for all
	/// of them. Infallible.
	fn on_unbalanceds<B>(amounts: impl Iterator<Item=Imbalance>) where Imbalance: crate::traits::Imbalance<B> {
		Self::on_unbalanced(amounts.fold(Imbalance::zero(), |i, x| x.merge(i)))
	}

	/// Handler for some imbalance. Infallible.
	fn on_unbalanced(amount: Imbalance) {
		amount.try_drop().unwrap_or_else(Self::on_nonzero_unbalanced)
	}

	/// Actually handle a non-zero imbalance. You probably want to implement this rather than
	/// `on_unbalanced`.
	fn on_nonzero_unbalanced(amount: Imbalance) { drop(amount); }
}

impl<Imbalance: TryDrop> OnUnbalanced<Imbalance> for () {}

/// Simple boolean for whether an account needs to be kept in existence.
#[derive(Copy, Clone, Eq, PartialEq)]
pub enum ExistenceRequirement {
	/// Operation must not result in the account going out of existence.
	///
	/// Note this implies that if the account never existed in the first place, then the operation
	/// may legitimately leave the account unchanged and still non-existent.
	KeepAlive,
	/// Operation may result in account going out of existence.
	AllowDeath,
}

/// A type for which some values make sense to be able to drop without further consideration.
pub trait TryDrop: Sized {
	/// Drop an instance cleanly. Only works if its value represents "no-operation".
	fn try_drop(self) -> Result<(), Self>;
}

/// A trait for a not-quite Linear Type that tracks an imbalance.
///
/// Functions that alter account balances return an object of this trait to
/// express how much account balances have been altered in aggregate. If
/// dropped, the currency system will take some default steps to deal with
/// the imbalance (`balances` module simply reduces or increases its
/// total issuance). Your module should generally handle it in some way,
/// good practice is to do so in a configurable manner using an
/// `OnUnbalanced` type for each situation in which your module needs to
/// handle an imbalance.
///
/// Imbalances can either be Positive (funds were added somewhere without
/// being subtracted elsewhere - e.g. a reward) or Negative (funds deducted
/// somewhere without an equal and opposite addition - e.g. a slash or
/// system fee payment).
///
/// Since they are unsigned, the actual type is always Positive or Negative.
/// The trait makes no distinction except to define the `Opposite` type.
///
/// New instances of zero value can be created (`zero`) and destroyed
/// (`drop_zero`).
///
/// Existing instances can be `split` and merged either consuming `self` with
/// `merge` or mutating `self` with `subsume`. If the target is an `Option`,
/// then `maybe_merge` and `maybe_subsume` might work better. Instances can
/// also be `offset` with an `Opposite` that is less than or equal to in value.
///
/// You can always retrieve the raw balance value using `peek`.
#[must_use]
pub trait Imbalance<Balance>: Sized + TryDrop {
	/// The oppositely imbalanced type. They come in pairs.
	type Opposite: Imbalance<Balance>;

	/// The zero imbalance. Can be destroyed with `drop_zero`.
	fn zero() -> Self;

	/// Drop an instance cleanly. Only works if its `self.value()` is zero.
	fn drop_zero(self) -> Result<(), Self>;

	/// Consume `self` and return two independent instances; the first
	/// is guaranteed to be at most `amount` and the second will be the remainder.
	fn split(self, amount: Balance) -> (Self, Self);

	/// Consume `self` and return two independent instances; the amounts returned will be in
	/// approximately the same ratio as `first`:`second`.
	///
	/// NOTE: This requires up to `first + second` room for a multiply, and `first + second` should
	/// fit into a `u32`. Overflow will safely saturate in both cases.
	fn ration(self, first: u32, second: u32) -> (Self, Self)
		where Balance: From<u32> + Saturating + Div<Output=Balance>
	{
		let total: u32 = first.saturating_add(second);
		let amount1 = self.peek().saturating_mul(first.into()) / total.into();
		self.split(amount1)
	}

	/// Consume self and add its two components, defined by the first component's balance,
	/// element-wise to two pre-existing Imbalances.
	///
	/// A convenient replacement for `split` and `merge`.
	fn split_merge(self, amount: Balance, others: (Self, Self)) -> (Self, Self) {
		let (a, b) = self.split(amount);
		(a.merge(others.0), b.merge(others.1))
	}

	/// Consume self and add its two components, defined by the ratio `first`:`second`,
	/// element-wise to two pre-existing Imbalances.
	///
	/// A convenient replacement for `split` and `merge`.
	fn ration_merge(self, first: u32, second: u32, others: (Self, Self)) -> (Self, Self)
		where Balance: From<u32> + Saturating + Div<Output=Balance>
	{
		let (a, b) = self.ration(first, second);
		(a.merge(others.0), b.merge(others.1))
	}

	/// Consume self and add its two components, defined by the first component's balance,
	/// element-wise into two pre-existing Imbalance refs.
	///
	/// A convenient replacement for `split` and `subsume`.
	fn split_merge_into(self, amount: Balance, others: &mut (Self, Self)) {
		let (a, b) = self.split(amount);
		others.0.subsume(a);
		others.1.subsume(b);
	}

	/// Consume self and add its two components, defined by the ratio `first`:`second`,
	/// element-wise to two pre-existing Imbalances.
	///
	/// A convenient replacement for `split` and `merge`.
	fn ration_merge_into(self, first: u32, second: u32, others: &mut (Self, Self))
		where Balance: From<u32> + Saturating + Div<Output=Balance>
	{
		let (a, b) = self.ration(first, second);
		others.0.subsume(a);
		others.1.subsume(b);
	}

	/// Consume `self` and an `other` to return a new instance that combines
	/// both.
	fn merge(self, other: Self) -> Self;

	/// Consume self to mutate `other` so that it combines both. Just like `subsume`, only with
	/// reversed arguments.
	fn merge_into(self, other: &mut Self) {
		other.subsume(self)
	}

	/// Consume `self` and maybe an `other` to return a new instance that combines
	/// both.
	fn maybe_merge(self, other: Option<Self>) -> Self {
		if let Some(o) = other {
			self.merge(o)
		} else {
			self
		}
	}

	/// Consume an `other` to mutate `self` into a new instance that combines
	/// both.
	fn subsume(&mut self, other: Self);

	/// Maybe consume an `other` to mutate `self` into a new instance that combines
	/// both.
	fn maybe_subsume(&mut self, other: Option<Self>) {
		if let Some(o) = other {
			self.subsume(o)
		}
	}

	/// Consume self and along with an opposite counterpart to return
	/// a combined result.
	///
	/// Returns `Ok` along with a new instance of `Self` if this instance has a
	/// greater value than the `other`. Otherwise returns `Err` with an instance of
	/// the `Opposite`. In both cases the value represents the combination of `self`
	/// and `other`.
	fn offset(self, other: Self::Opposite) -> Result<Self, Self::Opposite>;

	/// The raw value of self.
	fn peek(&self) -> Balance;
}

/// Either a positive or a negative imbalance.
pub enum SignedImbalance<B, P: Imbalance<B>>{
	/// A positive imbalance (funds have been created but none destroyed).
	Positive(P),
	/// A negative imbalance (funds have been destroyed but none created).
	Negative(P::Opposite),
}

impl<
	P: Imbalance<B, Opposite=N>,
	N: Imbalance<B, Opposite=P>,
	B: AtLeast32BitUnsigned + FullCodec + Copy + MaybeSerializeDeserialize + Debug + Default,
> SignedImbalance<B, P> {
	pub fn zero() -> Self {
		SignedImbalance::Positive(P::zero())
	}

	pub fn drop_zero(self) -> Result<(), Self> {
		match self {
			SignedImbalance::Positive(x) => x.drop_zero().map_err(SignedImbalance::Positive),
			SignedImbalance::Negative(x) => x.drop_zero().map_err(SignedImbalance::Negative),
		}
	}

	/// Consume `self` and an `other` to return a new instance that combines
	/// both.
	pub fn merge(self, other: Self) -> Self {
		match (self, other) {
			(SignedImbalance::Positive(one), SignedImbalance::Positive(other)) =>
				SignedImbalance::Positive(one.merge(other)),
			(SignedImbalance::Negative(one), SignedImbalance::Negative(other)) =>
				SignedImbalance::Negative(one.merge(other)),
			(SignedImbalance::Positive(one), SignedImbalance::Negative(other)) =>
				if one.peek() > other.peek() {
					SignedImbalance::Positive(one.offset(other).ok().unwrap_or_else(P::zero))
				} else {
					SignedImbalance::Negative(other.offset(one).ok().unwrap_or_else(N::zero))
				},
			(one, other) => other.merge(one),
		}
	}
}

/// Split an unbalanced amount two ways between a common divisor.
pub struct SplitTwoWays<
	Balance,
	Imbalance,
	Part1,
	Target1,
	Part2,
	Target2,
>(PhantomData<(Balance, Imbalance, Part1, Target1, Part2, Target2)>);

impl<
	Balance: From<u32> + Saturating + Div<Output=Balance>,
	I: Imbalance<Balance>,
	Part1: U32,
	Target1: OnUnbalanced<I>,
	Part2: U32,
	Target2: OnUnbalanced<I>,
> OnUnbalanced<I> for SplitTwoWays<Balance, I, Part1, Target1, Part2, Target2>
{
	fn on_nonzero_unbalanced(amount: I) {
		let total: u32 = Part1::VALUE + Part2::VALUE;
		let amount1 = amount.peek().saturating_mul(Part1::VALUE.into()) / total.into();
		let (imb1, imb2) = amount.split(amount1);
		Target1::on_unbalanced(imb1);
		Target2::on_unbalanced(imb2);
	}
}

/// Abstraction over a fungible assets system.
pub trait Currency<AccountId> {
	/// The balance of an account.
	type Balance: AtLeast32BitUnsigned + FullCodec + Copy + MaybeSerializeDeserialize + Debug +
		Default;

	/// The opaque token type for an imbalance. This is returned by unbalanced operations
	/// and must be dealt with. It may be dropped but cannot be cloned.
	type PositiveImbalance: Imbalance<Self::Balance, Opposite=Self::NegativeImbalance>;

	/// The opaque token type for an imbalance. This is returned by unbalanced operations
	/// and must be dealt with. It may be dropped but cannot be cloned.
	type NegativeImbalance: Imbalance<Self::Balance, Opposite=Self::PositiveImbalance>;

	// PUBLIC IMMUTABLES

	/// The combined balance of `who`.
	fn total_balance(who: &AccountId) -> Self::Balance;

	/// Same result as `slash(who, value)` (but without the side-effects) assuming there are no
	/// balance changes in the meantime and only the reserved balance is not taken into account.
	fn can_slash(who: &AccountId, value: Self::Balance) -> bool;

	/// The total amount of issuance in the system.
	fn total_issuance() -> Self::Balance;

	/// The minimum balance any single account may have. This is equivalent to the `Balances` module's
	/// `ExistentialDeposit`.
	fn minimum_balance() -> Self::Balance;

	/// Reduce the total issuance by `amount` and return the according imbalance. The imbalance will
	/// typically be used to reduce an account by the same amount with e.g. `settle`.
	///
	/// This is infallible, but doesn't guarantee that the entire `amount` is burnt, for example
	/// in the case of underflow.
	fn burn(amount: Self::Balance) -> Self::PositiveImbalance;

	/// Increase the total issuance by `amount` and return the according imbalance. The imbalance
	/// will typically be used to increase an account by the same amount with e.g.
	/// `resolve_into_existing` or `resolve_creating`.
	///
	/// This is infallible, but doesn't guarantee that the entire `amount` is issued, for example
	/// in the case of overflow.
	fn issue(amount: Self::Balance) -> Self::NegativeImbalance;

	/// Produce a pair of imbalances that cancel each other out exactly.
	///
	/// This is just the same as burning and issuing the same amount and has no effect on the
	/// total issuance.
	fn pair(amount: Self::Balance) -> (Self::PositiveImbalance, Self::NegativeImbalance) {
		(Self::burn(amount.clone()), Self::issue(amount))
	}

	/// The 'free' balance of a given account.
	///
	/// This is the only balance that matters in terms of most operations on tokens. It alone
	/// is used to determine the balance when in the contract execution environment. When this
	/// balance falls below the value of `ExistentialDeposit`, then the 'current account' is
	/// deleted: specifically `FreeBalance`.
	///
	/// `system::AccountNonce` is also deleted if `ReservedBalance` is also zero (it also gets
	/// collapsed to zero if it ever becomes less than `ExistentialDeposit`.
	fn free_balance(who: &AccountId) -> Self::Balance;

	/// Returns `Ok` iff the account is able to make a withdrawal of the given amount
	/// for the given reason. Basically, it's just a dry-run of `withdraw`.
	///
	/// `Err(...)` with the reason why not otherwise.
	fn ensure_can_withdraw(
		who: &AccountId,
		_amount: Self::Balance,
		reasons: WithdrawReasons,
		new_balance: Self::Balance,
	) -> DispatchResult;

	// PUBLIC MUTABLES (DANGEROUS)

	/// Transfer some liquid free balance to another staker.
	///
	/// This is a very high-level function. It will ensure all appropriate fees are paid
	/// and no imbalance in the system remains.
	fn transfer(
		source: &AccountId,
		dest: &AccountId,
		value: Self::Balance,
		existence_requirement: ExistenceRequirement,
	) -> DispatchResult;

	/// Deducts up to `value` from the combined balance of `who`, preferring to deduct from the
	/// free balance. This function cannot fail.
	///
	/// The resulting imbalance is the first item of the tuple returned.
	///
	/// As much funds up to `value` will be deducted as possible. If this is less than `value`,
	/// then a non-zero second item will be returned.
	fn slash(
		who: &AccountId,
		value: Self::Balance
	) -> (Self::NegativeImbalance, Self::Balance);

	/// Mints `value` to the free balance of `who`.
	///
	/// If `who` doesn't exist, nothing is done and an Err returned.
	fn deposit_into_existing(
		who: &AccountId,
		value: Self::Balance
	) -> result::Result<Self::PositiveImbalance, DispatchError>;

	/// Similar to deposit_creating, only accepts a `NegativeImbalance` and returns nothing on
	/// success.
	fn resolve_into_existing(
		who: &AccountId,
		value: Self::NegativeImbalance,
	) -> result::Result<(), Self::NegativeImbalance> {
		let v = value.peek();
		match Self::deposit_into_existing(who, v) {
			Ok(opposite) => Ok(drop(value.offset(opposite))),
			_ => Err(value),
		}
	}

	/// Adds up to `value` to the free balance of `who`. If `who` doesn't exist, it is created.
	///
	/// Infallible.
	fn deposit_creating(
		who: &AccountId,
		value: Self::Balance,
	) -> Self::PositiveImbalance;

	/// Similar to deposit_creating, only accepts a `NegativeImbalance` and returns nothing on
	/// success.
	fn resolve_creating(
		who: &AccountId,
		value: Self::NegativeImbalance,
	) {
		let v = value.peek();
		drop(value.offset(Self::deposit_creating(who, v)));
	}

	/// Removes some free balance from `who` account for `reason` if possible. If `liveness` is
	/// `KeepAlive`, then no less than `ExistentialDeposit` must be left remaining.
	///
	/// This checks any locks, vesting, and liquidity requirements. If the removal is not possible,
	/// then it returns `Err`.
	///
	/// If the operation is successful, this will return `Ok` with a `NegativeImbalance` whose value
	/// is `value`.
	fn withdraw(
		who: &AccountId,
		value: Self::Balance,
		reasons: WithdrawReasons,
		liveness: ExistenceRequirement,
	) -> result::Result<Self::NegativeImbalance, DispatchError>;

	/// Similar to withdraw, only accepts a `PositiveImbalance` and returns nothing on success.
	fn settle(
		who: &AccountId,
		value: Self::PositiveImbalance,
		reasons: WithdrawReasons,
		liveness: ExistenceRequirement,
	) -> result::Result<(), Self::PositiveImbalance> {
		let v = value.peek();
		match Self::withdraw(who, v, reasons, liveness) {
			Ok(opposite) => Ok(drop(value.offset(opposite))),
			_ => Err(value),
		}
	}

	/// Ensure an account's free balance equals some value; this will create the account
	/// if needed.
	///
	/// Returns a signed imbalance and status to indicate if the account was successfully updated or update
	/// has led to killing of the account.
	fn make_free_balance_be(
		who: &AccountId,
		balance: Self::Balance,
	) -> SignedImbalance<Self::Balance, Self::PositiveImbalance>;
}

/// Status of funds.
#[derive(PartialEq, Eq, Clone, Copy, Encode, Decode, RuntimeDebug)]
pub enum BalanceStatus {
	/// Funds are free, as corresponding to `free` item in Balances.
	Free,
	/// Funds are reserved, as corresponding to `reserved` item in Balances.
	Reserved,
}

/// A currency where funds can be reserved from the user.
pub trait ReservableCurrency<AccountId>: Currency<AccountId> {
	/// Same result as `reserve(who, value)` (but without the side-effects) assuming there
	/// are no balance changes in the meantime.
	fn can_reserve(who: &AccountId, value: Self::Balance) -> bool;

	/// Deducts up to `value` from reserved balance of `who`. This function cannot fail.
	///
	/// As much funds up to `value` will be deducted as possible. If the reserve balance of `who`
	/// is less than `value`, then a non-zero second item will be returned.
	fn slash_reserved(
		who: &AccountId,
		value: Self::Balance
	) -> (Self::NegativeImbalance, Self::Balance);

	/// The amount of the balance of a given account that is externally reserved; this can still get
	/// slashed, but gets slashed last of all.
	///
	/// This balance is a 'reserve' balance that other subsystems use in order to set aside tokens
	/// that are still 'owned' by the account holder, but which are suspendable.
	///
	/// When this balance falls below the value of `ExistentialDeposit`, then this 'reserve account'
	/// is deleted: specifically, `ReservedBalance`.
	///
	/// `system::AccountNonce` is also deleted if `FreeBalance` is also zero (it also gets
	/// collapsed to zero if it ever becomes less than `ExistentialDeposit`.
	fn reserved_balance(who: &AccountId) -> Self::Balance;

	/// Moves `value` from balance to reserved balance.
	///
	/// If the free balance is lower than `value`, then no funds will be moved and an `Err` will
	/// be returned to notify of this. This is different behavior than `unreserve`.
	fn reserve(who: &AccountId, value: Self::Balance) -> DispatchResult;

	/// Moves up to `value` from reserved balance to free balance. This function cannot fail.
	///
	/// As much funds up to `value` will be moved as possible. If the reserve balance of `who`
	/// is less than `value`, then the remaining amount will be returned.
	///
	/// # NOTES
	///
	/// - This is different from `reserve`.
	/// - If the remaining reserved balance is less than `ExistentialDeposit`, it will
	/// invoke `on_reserved_too_low` and could reap the account.
	fn unreserve(who: &AccountId, value: Self::Balance) -> Self::Balance;

	/// Moves up to `value` from reserved balance of account `slashed` to balance of account
	/// `beneficiary`. `beneficiary` must exist for this to succeed. If it does not, `Err` will be
	/// returned. Funds will be placed in either the `free` balance or the `reserved` balance,
	/// depending on the `status`.
	///
	/// As much funds up to `value` will be deducted as possible. If this is less than `value`,
	/// then `Ok(non_zero)` will be returned.
	fn repatriate_reserved(
		slashed: &AccountId,
		beneficiary: &AccountId,
		value: Self::Balance,
		status: BalanceStatus,
	) -> result::Result<Self::Balance, DispatchError>;
}

/// An identifier for a lock. Used for disambiguating different locks so that
/// they can be individually replaced or removed.
pub type LockIdentifier = [u8; 8];

/// A currency whose accounts can have liquidity restrictions.
pub trait LockableCurrency<AccountId>: Currency<AccountId> {
	/// The quantity used to denote time; usually just a `BlockNumber`.
	type Moment;

	/// The maximum number of locks a user should have on their account.
	type MaxLocks: Get<u32>;

	/// Create a new balance lock on account `who`.
	///
	/// If the new lock is valid (i.e. not already expired), it will push the struct to
	/// the `Locks` vec in storage. Note that you can lock more funds than a user has.
	///
	/// If the lock `id` already exists, this will update it.
	fn set_lock(
		id: LockIdentifier,
		who: &AccountId,
		amount: Self::Balance,
		reasons: WithdrawReasons,
	);

	/// Changes a balance lock (selected by `id`) so that it becomes less liquid in all
	/// parameters or creates a new one if it does not exist.
	///
	/// Calling `extend_lock` on an existing lock `id` differs from `set_lock` in that it
	/// applies the most severe constraints of the two, while `set_lock` replaces the lock
	/// with the new parameters. As in, `extend_lock` will set:
	/// - maximum `amount`
	/// - bitwise mask of all `reasons`
	fn extend_lock(
		id: LockIdentifier,
		who: &AccountId,
		amount: Self::Balance,
		reasons: WithdrawReasons,
	);

	/// Remove an existing lock.
	fn remove_lock(
		id: LockIdentifier,
		who: &AccountId,
	);
}

/// A vesting schedule over a currency. This allows a particular currency to have vesting limits
/// applied to it.
pub trait VestingSchedule<AccountId> {
	/// The quantity used to denote time; usually just a `BlockNumber`.
	type Moment;

	/// The currency that this schedule applies to.
	type Currency: Currency<AccountId>;

	/// Get the amount that is currently being vested and cannot be transferred out of this account.
	/// Returns `None` if the account has no vesting schedule.
	fn vesting_balance(who: &AccountId) -> Option<<Self::Currency as Currency<AccountId>>::Balance>;

	/// Adds a vesting schedule to a given account.
	///
	/// If there already exists a vesting schedule for the given account, an `Err` is returned
	/// and nothing is updated.
	///
	/// Is a no-op if the amount to be vested is zero.
	///
	/// NOTE: This doesn't alter the free balance of the account.
	fn add_vesting_schedule(
		who: &AccountId,
		locked: <Self::Currency as Currency<AccountId>>::Balance,
		per_block: <Self::Currency as Currency<AccountId>>::Balance,
		starting_block: Self::Moment,
	) -> DispatchResult;

	/// Remove a vesting schedule for a given account.
	///
	/// NOTE: This doesn't alter the free balance of the account.
	fn remove_vesting_schedule(who: &AccountId);
}

bitflags! {
	/// Reasons for moving funds out of an account.
	#[derive(Encode, Decode)]
	pub struct WithdrawReasons: i8 {
		/// In order to pay for (system) transaction costs.
		const TRANSACTION_PAYMENT = 0b00000001;
		/// In order to transfer ownership.
		const TRANSFER = 0b00000010;
		/// In order to reserve some funds for a later return or repatriation.
		const RESERVE = 0b00000100;
		/// In order to pay some other (higher-level) fees.
		const FEE = 0b00001000;
		/// In order to tip a validator for transaction inclusion.
		const TIP = 0b00010000;
	}
}

impl WithdrawReasons {
	/// Choose all variants except for `one`.
	///
	/// ```rust
	/// # use fabric_support::traits::WithdrawReasons;
	/// # fn main() {
	/// assert_eq!(
	/// 	WithdrawReasons::FEE | WithdrawReasons::TRANSFER | WithdrawReasons::RESERVE | WithdrawReasons::TIP,
	/// 	WithdrawReasons::except(WithdrawReasons::TRANSACTION_PAYMENT),
	///	);
	/// # }
	/// ```
	pub fn except(one: WithdrawReasons) -> WithdrawReasons {
		let mut flags = Self::all();
		flags.toggle(one);
		flags
	}
}

pub trait Time {
	type Moment: AtLeast32Bit + Parameter + Default + Copy;

	fn now() -> Self::Moment;
}

/// Trait to deal with unix time.
pub trait UnixTime {
	/// Return duration since `SystemTime::UNIX_EPOCH`.
	fn now() -> core::time::Duration;
}

/// Trait for type that can handle incremental changes to a set of account IDs.
pub trait ChangeMembers<AccountId: Clone + Ord> {
	/// A number of members `incoming` just joined the set and replaced some `outgoing` ones. The
	/// new set is given by `new`, and need not be sorted.
	///
	/// This resets any previous value of prime.
	fn change_members(incoming: &[AccountId], outgoing: &[AccountId], mut new: Vec<AccountId>) {
		new.sort();
		Self::change_members_sorted(incoming, outgoing, &new[..]);
	}

	/// A number of members `_incoming` just joined the set and replaced some `_outgoing` ones. The
	/// new set is thus given by `sorted_new` and **must be sorted**.
	///
	/// NOTE: This is the only function that needs to be implemented in `ChangeMembers`.
	///
	/// This resets any previous value of prime.
	fn change_members_sorted(
		incoming: &[AccountId],
		outgoing: &[AccountId],
		sorted_new: &[AccountId],
	);

	/// Set the new members; they **must already be sorted**. This will compute the diff and use it to
	/// call `change_members_sorted`.
	///
	/// This resets any previous value of prime.
	fn set_members_sorted(new_members: &[AccountId], old_members: &[AccountId]) {
		let (incoming, outgoing) = Self::compute_members_diff_sorted(new_members, old_members);
		Self::change_members_sorted(&incoming[..], &outgoing[..], &new_members);
	}

	/// Compute diff between new and old members; they **must already be sorted**.
	///
	/// Returns incoming and outgoing members.
	fn compute_members_diff_sorted(
		new_members: &[AccountId],
		old_members: &[AccountId],
	) -> (Vec<AccountId>, Vec<AccountId>) {
		let mut old_iter = old_members.iter();
		let mut new_iter = new_members.iter();
		let mut incoming = Vec::new();
		let mut outgoing = Vec::new();
		let mut old_i = old_iter.next();
		let mut new_i = new_iter.next();
		loop {
			match (old_i, new_i) {
				(None, None) => break,
				(Some(old), Some(new)) if old == new => {
					old_i = old_iter.next();
					new_i = new_iter.next();
				}
				(Some(old), Some(new)) if old < new => {
					outgoing.push(old.clone());
					old_i = old_iter.next();
				}
				(Some(old), None) => {
					outgoing.push(old.clone());
					old_i = old_iter.next();
				}
				(_, Some(new)) => {
					incoming.push(new.clone());
					new_i = new_iter.next();
				}
			}
		}
		(incoming, outgoing)
	}

	/// Set the prime member.
	fn set_prime(_prime: Option<AccountId>) {}

	/// Get the current prime.
	fn get_prime() -> Option<AccountId> {
		None
	}
}

impl<T: Clone + Ord> ChangeMembers<T> for () {
	fn change_members(_: &[T], _: &[T], _: Vec<T>) {}
	fn change_members_sorted(_: &[T], _: &[T], _: &[T]) {}
	fn set_members_sorted(_: &[T], _: &[T]) {}
	fn set_prime(_: Option<T>) {}
}

/// Trait for type that can handle the initialization of account IDs at genesis.
pub trait InitializeMembers<AccountId> {
	/// Initialize the members to the given `members`.
	fn initialize_members(members: &[AccountId]);
}

impl<T> InitializeMembers<T> for () {
	fn initialize_members(_: &[T]) {}
}

// A trait that is able to provide randomness.
pub trait Randomness<Output> {
	/// Get a "random" value
	///
	/// Being a deterministic blockchain, real randomness is difficult to come by. This gives you
	/// something that approximates it. At best, this will be randomness which was
	/// hard to predict a long time ago, but that has become easy to predict recently.
	///
	/// `subject` is a context identifier and allows you to get a
	/// different result to other callers of this function; use it like
	/// `random(&b"my context"[..])`.
	fn random(subject: &[u8]) -> Output;

	/// Get the basic random seed.
	///
	/// In general you won't want to use this, but rather `Self::random` which allows you to give a
	/// subject for the random result and whose value will be independently low-influence random
	/// from any other such seeds.
	fn random_seed() -> Output {
		Self::random(&[][..])
	}
}

/// Provides an implementation of [`Randomness`] that should only be used in tests!
pub struct TestRandomness;

impl<Output: Decode + Default> Randomness<Output> for TestRandomness {
	fn random(subject: &[u8]) -> Output {
		Output::decode(&mut TrailingZeroInput::new(subject)).unwrap_or_default()
	}
}

/// Trait to be used by block producing consensus engine modules to determine
/// how late the current block is (e.g. in a slot-based proposal mechanism how
/// many slots were skipped since the previous block).
pub trait Lateness<N> {
	/// Returns a generic measure of how late the current block is compared to
	/// its parent.
	fn lateness(&self) -> N;
}

impl<N: Zero> Lateness<N> for () {
	fn lateness(&self) -> N {
		Zero::zero()
	}
}

/// Implementors of this trait provide information about whether or not some validator has
/// been registered with them. The [Session module](../../noble_session/index.html) is an implementor.
pub trait ValidatorRegistration<ValidatorId> {
	/// Returns true if the provided validator ID has been registered with the implementing runtime
	/// module
	fn is_registered(id: &ValidatorId) -> bool;
}

/// Provides information about the noble setup in the runtime.
///
/// An implementor should be able to provide information about each noble that
/// is configured in `construct_runtime!`.
pub trait NobleInfo {
	/// Convert the given noble `P` into its index as configured in the runtime.
	fn index<P: 'static>() -> Option<usize>;
	/// Convert the given noble `P` into its name as configured in the runtime.
	fn name<P: 'static>() -> Option<&'static str>;
}

impl NobleInfo for () {
	fn index<P: 'static>() -> Option<usize> { Some(0) }
	fn name<P: 'static>() -> Option<&'static str> { Some("test") }
}

/// The function and noble name of the Call.
#[derive(Clone, Eq, PartialEq, Default, RuntimeDebug)]
pub struct CallMetadata {
	/// Name of the function.
	pub function_name: &'static str,
	/// Name of the noble to which the function belongs.
	pub noble_name: &'static str,
}

/// Gets the function name of the Call.
pub trait GetCallName {
	/// Return all function names.
	fn get_call_names() -> &'static [&'static str];
	/// Return the function name of the Call.
	fn get_call_name(&self) -> &'static str;
}

/// Gets the metadata for the Call - function name and noble name.
pub trait GetCallMetadata {
	/// Return all module names.
	fn get_module_names() -> &'static [&'static str];
	/// Return all function names for the given `module`.
	fn get_call_names(module: &str) -> &'static [&'static str];
	/// Return a [`CallMetadata`], containing function and noble name of the Call.
	fn get_call_metadata(&self) -> CallMetadata;
}

/// The block finalization trait.
///
/// Implementing this lets you express what should happen for your noble when the block is ending.
#[impl_for_tuples(30)]
pub trait OnFinalize<BlockNumber> {
	/// The block is being finalized. Implement to have something happen.
	///
	/// NOTE: This function is called AFTER ALL extrinsics in a block are applied,
	/// including inherent extrinsics.
	fn on_finalize(_n: BlockNumber) {}
}

/// The block initialization trait.
///
/// Implementing this lets you express what should happen for your noble when the block is
/// beginning (right before the first extrinsic is executed).
pub trait OnInitialize<BlockNumber> {
	/// The block is being initialized. Implement to have something happen.
	///
	/// Return the non-negotiable weight consumed in the block.
	///
	/// NOTE: This function is called BEFORE ANY extrinsic in a block is applied,
	/// including inherent extrinsics. Hence for instance, if you runtime includes
	/// `noble_timestamp`, the `timestamp` is not yet up to date at this point.
	fn on_initialize(_n: BlockNumber) -> crate::weights::Weight { 0 }
}

#[impl_for_tuples(30)]
impl<BlockNumber: Clone> OnInitialize<BlockNumber> for Tuple {
	fn on_initialize(_n: BlockNumber) -> crate::weights::Weight {
		let mut weight = 0;
		for_tuples!( #( weight = weight.saturating_add(Tuple::on_initialize(_n.clone())); )* );
		weight
	}
}

/// A trait that will be called at genesis.
///
/// Implementing this trait for a noble let's you express operations that should
/// happen at genesis. It will be called in an externalities provided environment and
/// will see the genesis state after all nobles have written their genesis state.
#[impl_for_tuples(30)]
pub trait OnGenesis {
	/// Something that should happen at genesis.
	fn on_genesis() {}
}

/// The runtime upgrade trait.
///
/// Implementing this lets you express what should happen when the runtime upgrades,
/// and changes may need to occur to your module.
pub trait OnRuntimeUpgrade {
	/// Perform a module upgrade.
	///
	/// # Warning
	///
	/// This function will be called before we initialized any runtime state, aka `on_initialize`
	/// wasn't called yet. So, information like the block number and any other
	/// block local data are not accessible.
	///
	/// Return the non-negotiable weight consumed for runtime upgrade.
	fn on_runtime_upgrade() -> crate::weights::Weight { 0 }
}

#[impl_for_tuples(30)]
impl OnRuntimeUpgrade for Tuple {
	fn on_runtime_upgrade() -> crate::weights::Weight {
		let mut weight = 0;
		for_tuples!( #( weight = weight.saturating_add(Tuple::on_runtime_upgrade()); )* );
		weight
	}
}

/// Off-chain computation trait.
///
/// Implementing this trait on a module allows you to perform long-running tasks
/// that make (by default) validators generate transactions that feed results
/// of those long-running computations back on chain.
///
/// NOTE: This function runs off-chain, so it can access the block state,
/// but cannot preform any alterations. More specifically alterations are
/// not forbidden, but they are not persisted in any way after the worker
/// has finished.
#[impl_for_tuples(30)]
pub trait OffchainWorker<BlockNumber> {
	/// This function is being called after every block import (when fully synced).
	///
	/// Implement this and use any of the `Offchain` `tet_io` set of APIs
	/// to perform off-chain computations, calls and submit transactions
	/// with results to trigger any on-chain changes.
	/// Any state alterations are lost and are not persisted.
	fn offchain_worker(_n: BlockNumber) {}
}

pub mod schedule {
	use super::*;

	/// Information relating to the period of a scheduled task. First item is the length of the
	/// period and the second is the number of times it should be executed in total before the task
	/// is considered finished and removed.
	pub type Period<BlockNumber> = (BlockNumber, u32);

	/// Priority with which a call is scheduled. It's just a linear amount with lowest values meaning
	/// higher priority.
	pub type Priority = u8;

	/// The dispatch time of a scheduled task.
	#[derive(Encode, Decode, Copy, Clone, PartialEq, Eq, RuntimeDebug)]
	pub enum DispatchTime<BlockNumber> {
		/// At specified block.
		At(BlockNumber),
		/// After specified number of blocks.
		After(BlockNumber),
	}

	/// The highest priority. We invert the value so that normal sorting will place the highest
	/// priority at the beginning of the list.
	pub const HIGHEST_PRIORITY: Priority = 0;
	/// Anything of this value or lower will definitely be scheduled on the block that they ask for, even
	/// if it breaches the `MaximumWeight` limitation.
	pub const HARD_DEADLINE: Priority = 63;
	/// The lowest priority. Most stuff should be around here.
	pub const LOWEST_PRIORITY: Priority = 255;

	/// A type that can be used as a scheduler.
	pub trait Anon<BlockNumber, Call, Origin> {
		/// An address which can be used for removing a scheduled task.
		type Address: Codec + Clone + Eq + EncodeLike + Debug;

		/// Schedule a dispatch to happen at the beginning of some block in the future.
		///
		/// This is not named.
		fn schedule(
			when: DispatchTime<BlockNumber>,
			maybe_periodic: Option<Period<BlockNumber>>,
			priority: Priority,
			origin: Origin,
			call: Call
		) -> Result<Self::Address, DispatchError>;

		/// Cancel a scheduled task. If periodic, then it will cancel all further instances of that,
		/// also.
		///
		/// Will return an error if the `address` is invalid.
		///
		/// NOTE: This guaranteed to work only *before* the point that it is due to be executed.
		/// If it ends up being delayed beyond the point of execution, then it cannot be cancelled.
		///
		/// NOTE2: This will not work to cancel periodic tasks after their initial execution. For
		/// that, you must name the task explicitly using the `Named` trait.
		fn cancel(address: Self::Address) -> Result<(), ()>;

		/// Reschedule a task. For one-off tasks, this dispatch is guaranteed to succeed
		/// only if it is executed *before* the currently scheduled block. For periodic tasks,
		/// this dispatch is guaranteed to succeed only before the *initial* execution; for
		/// others, use `reschedule_named`.
		///
		/// Will return an error if the `address` is invalid.
		fn reschedule(
			address: Self::Address,
			when: DispatchTime<BlockNumber>,
		) -> Result<Self::Address, DispatchError>;

		/// Return the next dispatch time for a given task.
		///
		/// Will return an error if the `address` is invalid.
		fn next_dispatch_time(address: Self::Address) -> Result<BlockNumber, ()>;
	}

	/// A type that can be used as a scheduler.
	pub trait Named<BlockNumber, Call, Origin> {
		/// An address which can be used for removing a scheduled task.
		type Address: Codec + Clone + Eq + EncodeLike + tetcore_std::fmt::Debug;

		/// Schedule a dispatch to happen at the beginning of some block in the future.
		///
		/// - `id`: The identity of the task. This must be unique and will return an error if not.
		fn schedule_named(
			id: Vec<u8>,
			when: DispatchTime<BlockNumber>,
			maybe_periodic: Option<Period<BlockNumber>>,
			priority: Priority,
			origin: Origin,
			call: Call
		) -> Result<Self::Address, ()>;

		/// Cancel a scheduled, named task. If periodic, then it will cancel all further instances
		/// of that, also.
		///
		/// Will return an error if the `id` is invalid.
		///
		/// NOTE: This guaranteed to work only *before* the point that it is due to be executed.
		/// If it ends up being delayed beyond the point of execution, then it cannot be cancelled.
		fn cancel_named(id: Vec<u8>) -> Result<(), ()>;

		/// Reschedule a task. For one-off tasks, this dispatch is guaranteed to succeed
		/// only if it is executed *before* the currently scheduled block.
		fn reschedule_named(
			id: Vec<u8>,
			when: DispatchTime<BlockNumber>,
		) -> Result<Self::Address, DispatchError>;

		/// Return the next dispatch time for a given task.
		///
		/// Will return an error if the `id` is invalid.
		fn next_dispatch_time(id: Vec<u8>) -> Result<BlockNumber, ()>;
	}
}

/// Some sort of check on the origin is performed by this object.
pub trait EnsureOrigin<OuterOrigin> {
	/// A return type.
	type Success;
	/// Perform the origin check.
	fn ensure_origin(o: OuterOrigin) -> result::Result<Self::Success, BadOrigin> {
		Self::try_origin(o).map_err(|_| BadOrigin)
	}
	/// Perform the origin check.
	fn try_origin(o: OuterOrigin) -> result::Result<Self::Success, OuterOrigin>;

	/// Returns an outer origin capable of passing `try_origin` check.
	///
	/// ** Should be used for benchmarking only!!! **
	#[cfg(feature = "runtime-benchmarks")]
	fn successful_origin() -> OuterOrigin;
}

/// Type that can be dispatched with an origin but without checking the origin filter.
///
/// Implemented for noble dispatchable type by `decl_module` and for runtime dispatchable by
/// `construct_runtime` and `impl_outer_dispatch`.
pub trait UnfilteredDispatchable {
	/// The origin type of the runtime, (i.e. `fabric_system::Config::Origin`).
	type Origin;

	/// Dispatch this call but do not check the filter in origin.
	fn dispatch_bypass_filter(self, origin: Self::Origin) -> crate::dispatch::DispatchResultWithPostInfo;
}

/// Methods available on `fabric_system::Config::Origin`.
pub trait OriginTrait: Sized {
	/// Runtime call type, as in `fabric_system::Config::Call`
	type Call;

	/// The caller origin, overarching type of all nobles origins.
	type NoblesOrigin;

	/// The AccountId used across the system.
	type AccountId;

	/// Add a filter to the origin.
	fn add_filter(&mut self, filter: impl Fn(&Self::Call) -> bool + 'static);

	/// Reset origin filters to default one, i.e `fabric_system::Config::BaseCallFilter`.
	fn reset_filter(&mut self);

	/// Replace the caller with caller from the other origin
	fn set_caller_from(&mut self, other: impl Into<Self>);

	/// Filter the call, if false then call is filtered out.
	fn filter_call(&self, call: &Self::Call) -> bool;

	/// Get the caller.
	fn caller(&self) -> &Self::NoblesOrigin;

	/// Create with system none origin and `fabric-system::Config::BaseCallFilter`.
	fn none() -> Self;

	/// Create with system root origin and no filter.
	fn root() -> Self;

	/// Create with system signed origin and `fabric-system::Config::BaseCallFilter`.
	fn signed(by: Self::AccountId) -> Self;
}

/// Trait to be used when types are exactly same.
///
/// This allow to convert back and forth from type, a reference and a mutable reference.
pub trait IsType<T>: Into<T> + From<T> {
	/// Cast reference.
	fn from_ref(t: &T) -> &Self;

	/// Cast reference.
	fn into_ref(&self) -> &T;

	/// Cast mutable reference.
	fn from_mut(t: &mut T) -> &mut Self;

	/// Cast mutable reference.
	fn into_mut(&mut self) -> &mut T;
}

impl<T> IsType<T> for T {
	fn from_ref(t: &T) -> &Self { t }
	fn into_ref(&self) -> &T { self }
	fn from_mut(t: &mut T) -> &mut Self { t }
	fn into_mut(&mut self) -> &mut T { self }
}

/// An instance of a noble in the storage.
///
/// It is required that these instances are unique, to support multiple instances per noble in the same runtime!
///
/// E.g. for module MyModule default instance will have prefix "MyModule" and other instances
/// "InstanceNMyModule".
pub trait Instance: 'static {
	/// Unique module prefix. E.g. "InstanceNMyModule" or "MyModule"
	const PREFIX: &'static str;
}

/// An instance of a storage in a noble.
///
/// Define an instance for an individual storage inside a noble.
/// The noble prefix is used to isolate the storage between nobles, and the storage prefix is
/// used to isolate storages inside a noble.
///
/// NOTE: These information can be used to define storages in noble such as a `StorageMap` which
/// can use keys after `twox_128(noble_prefix())++twox_128(STORAGE_PREFIX)`
pub trait StorageInstance {
	/// Prefix of a noble to isolate it from other nobles.
	fn noble_prefix() -> &'static str;

	/// Prefix given to a storage to isolate from other storages in the noble.
	const STORAGE_PREFIX: &'static str;
}

/// Implement Get by returning Default for any type that implements Default.
pub struct GetDefault;
impl<T: Default> crate::traits::Get<T> for GetDefault {
	fn get() -> T {
		T::default()
	}
}

/// A trait similar to `Convert` to convert values from `B` an abstract balance type
/// into u64 and back from u128. (This conversion is used in election and other places where complex
/// calculation over balance type is needed)
///
/// Total issuance of the currency is passed in, but an implementation of this trait may or may not
/// use it.
///
/// # WARNING
///
/// the total issuance being passed in implies that the implementation must be aware of the fact
/// that its values can affect the outcome. This implies that if the vote value is dependent on the
/// total issuance, it should never ber written to storage for later re-use.
pub trait CurrencyToVote<B> {
	/// Convert balance to u64.
	fn to_vote(value: B, issuance: B) -> u64;

	/// Convert u128 to balance.
	fn to_currency(value: u128, issuance: B) -> B;
}

/// An implementation of `CurrencyToVote` tailored for chain's that have a balance type of u128.
///
/// The factor is the `(total_issuance / u64::max()).max(1)`, represented as u64. Let's look at the
/// important cases:
///
/// If the chain's total issuance is less than u64::max(), this will always be 1, which means that
/// the factor will not have any effect. In this case, any account's balance is also less. Thus,
/// both of the conversions are basically an `as`; Any balance can fit in u64.
///
/// If the chain's total issuance is more than 2*u64::max(), then a factor might be multiplied and
/// divided upon conversion.
pub struct U128CurrencyToVote;

impl U128CurrencyToVote {
	fn factor(issuance: u128) -> u128 {
		(issuance / u64::max_value() as u128).max(1)
	}
}

impl CurrencyToVote<u128> for U128CurrencyToVote {
	fn to_vote(value: u128, issuance: u128) -> u64 {
		(value / Self::factor(issuance)).saturated_into()
	}

	fn to_currency(value: u128, issuance: u128) -> u128 {
		value.saturating_mul(Self::factor(issuance))
	}
}


/// A naive implementation of `CurrencyConvert` that simply saturates all conversions.
///
/// # Warning
///
/// This is designed to be used mostly for testing. Use with care, and think about the consequences.
pub struct SaturatingCurrencyToVote;

impl<B: UniqueSaturatedInto<u64> + UniqueSaturatedFrom<u128>> CurrencyToVote<B> for SaturatingCurrencyToVote {
	fn to_vote(value: B, _: B) -> u64 {
		value.unique_saturated_into()
	}

	fn to_currency(value: u128, _: B) -> B {
		B::unique_saturated_from(value)
	}
}

/// Something that can be checked to be a of sub type `T`.
///
/// This is useful for enums where each variant encapsulates a different sub type, and
/// you need access to these sub types.
///
/// For example, in FABRIC, this trait is implemented for the runtime `Call` enum. Nobles use this
/// to check if a certain call is an instance of the local noble's `Call` enum.
///
/// # Example
///
/// ```
/// # use fabric_support::traits::IsSubType;
///
/// enum Test {
///     String(String),
///     U32(u32),
/// }
///
/// impl IsSubType<String> for Test {
///     fn is_sub_type(&self) -> Option<&String> {
///         match self {
///             Self::String(ref r) => Some(r),
///             _ => None,
///         }
///     }
/// }
///
/// impl IsSubType<u32> for Test {
///     fn is_sub_type(&self) -> Option<&u32> {
///         match self {
///             Self::U32(ref r) => Some(r),
///             _ => None,
///         }
///     }
/// }
///
/// fn main() {
///     let data = Test::String("test".into());
///
///     assert_eq!("test", IsSubType::<String>::is_sub_type(&data).unwrap().as_str());
/// }
/// ```
pub trait IsSubType<T> {
	/// Returns `Some(_)` if `self` is an instance of sub type `T`.
	fn is_sub_type(&self) -> Option<&T>;
}

/// The noble hooks trait. Implementing this lets you express some logic to execute.
pub trait Hooks<BlockNumber> {
	/// The block is being finalized. Implement to have something happen.
	fn on_finalize(_n: BlockNumber) {}

	/// The block is being initialized. Implement to have something happen.
	///
	/// Return the non-negotiable weight consumed in the block.
	fn on_initialize(_n: BlockNumber) -> crate::weights::Weight { 0 }

	/// Perform a module upgrade.
	///
	/// NOTE: this doesn't include all noble logic triggered on runtime upgrade. For instance it
	/// doesn't include the write of the noble version in storage. The final complete logic
	/// triggered on runtime upgrade is given by implementation of `OnRuntimeUpgrade` trait by
	/// `Noble`.
	///
	/// # Warning
	///
	/// This function will be called before we initialized any runtime state, aka `on_initialize`
	/// wasn't called yet. So, information like the block number and any other
	/// block local data are not accessible.
	///
	/// Return the non-negotiable weight consumed for runtime upgrade.
	fn on_runtime_upgrade() -> crate::weights::Weight { 0 }

	/// Implementing this function on a module allows you to perform long-running tasks
	/// that make (by default) validators generate transactions that feed results
	/// of those long-running computations back on chain.
	///
	/// NOTE: This function runs off-chain, so it can access the block state,
	/// but cannot preform any alterations. More specifically alterations are
	/// not forbidden, but they are not persisted in any way after the worker
	/// has finished.
	///
	/// This function is being called after every block import (when fully synced).
	///
	/// Implement this and use any of the `Offchain` `tet_io` set of APIs
	/// to perform off-chain computations, calls and submit transactions
	/// with results to trigger any on-chain changes.
	/// Any state alterations are lost and are not persisted.
	fn offchain_worker(_n: BlockNumber) {}

	/// Run integrity test.
	///
	/// The test is not executed in a externalities provided environment.
	fn integrity_test() {}
}

/// A trait to define the build function of a genesis config, T and I are placeholder for noble
/// trait and noble instance.
#[cfg(feature = "std")]
pub trait GenesisBuild<T, I=()>: Default + MaybeSerializeDeserialize {
	/// The build function is called within an externalities allowing storage APIs.
	/// Thus one can write to storage using regular noble storages.
	fn build(&self);

	/// Build the storage using `build` inside default storage.
	fn build_storage(&self) -> Result<tp_runtime::Storage, String> {
		let mut storage = Default::default();
		self.assimilate_storage(&mut storage)?;
		Ok(storage)
	}

	/// Assimilate the storage for this module into pre-existing overlays.
	fn assimilate_storage(&self, storage: &mut tp_runtime::Storage) -> Result<(), String> {
		tp_state_machine::BasicExternalities::execute_with_storage(storage, || {
			self.build();
			Ok(())
		})
	}
}

/// The storage key postfix that is used to store the [`NobleVersion`] per noble.
///
/// The full storage key is built by using:
/// Twox128([`NobleInfo::name`]) ++ Twox128([`NOBLE_VERSION_STORAGE_KEY_POSTFIX`])
pub const NOBLE_VERSION_STORAGE_KEY_POSTFIX: &[u8] = b":__NOBLE_VERSION__:";

/// The version of a noble.
///
/// Each noble version is stored in the state under a fixed key. See
/// [`NOBLE_VERSION_STORAGE_KEY_POSTFIX`] for how this key is built.
#[derive(RuntimeDebug, Eq, PartialEq, Encode, Decode, Ord, Clone, Copy)]
pub struct NobleVersion {
	/// The major version of the noble.
	pub major: u16,
	/// The minor version of the noble.
	pub minor: u8,
	/// The patch version of the noble.
	pub patch: u8,
}

impl NobleVersion {
	/// Creates a new instance of `Self`.
	pub fn new(major: u16, minor: u8, patch: u8) -> Self {
		Self {
			major,
			minor,
			patch,
		}
	}

	/// Returns the storage key for a noble version.
	///
	/// See [`NOBLE_VERSION_STORAGE_KEY_POSTFIX`] on how this key is built.
	///
	/// Returns `None` if the given `PI` returned a `None` as name for the given
	/// `Noble`.
	pub fn storage_key<PI: NobleInfo, Noble: 'static>() -> Option<[u8; 32]> {
		let noble_name = PI::name::<Noble>()?;

		let noble_name = tet_io::hashing::twox_128(noble_name.as_bytes());
		let postfix = tet_io::hashing::twox_128(NOBLE_VERSION_STORAGE_KEY_POSTFIX);

		let mut final_key = [0u8; 32];
		final_key[..16].copy_from_slice(&noble_name);
		final_key[16..].copy_from_slice(&postfix);

		Some(final_key)
	}

	/// Put this noble version into the storage.
	///
	/// It will use the storage key that is associated with the given `Noble`.
	///
	/// # Panics
	///
	/// This function will panic iff `Noble` can not be found by `NobleInfo`.
	/// In a runtime that is put together using
	/// [`construct_runtime!`](crate::construct_runtime) this should never happen.
	///
	/// It will also panic if this function isn't executed in an externalities
	/// provided environment.
	pub fn put_into_storage<PI: NobleInfo, Noble: 'static>(&self) {
		let key = Self::storage_key::<PI, Noble>()
			.expect("Every active noble has a name in the runtime; qed");

		crate::storage::unhashed::put(&key, self);
	}
}

impl tetcore_std::cmp::PartialOrd for NobleVersion {
	fn partial_cmp(&self, other: &Self) -> Option<tetcore_std::cmp::Ordering> {
		let res = self.major
			.cmp(&other.major)
			.then_with(||
				self.minor
					.cmp(&other.minor)
					.then_with(|| self.patch.cmp(&other.patch)
			));

		Some(res)
	}
}

/// Provides version information about a noble.
///
/// This trait provides two functions for returning the version of a
/// noble. There is a state where both functions can return distinct versions.
/// See [`GetNobleVersion::storage_version`] for more information about this.
pub trait GetNobleVersion {
	/// Returns the current version of the noble.
	fn current_version() -> NobleVersion;

	/// Returns the version of the noble that is stored in storage.
	///
	/// Most of the time this will return the exact same version as
	/// [`GetNobleVersion::current_version`]. Only when being in
	/// a state after a runtime upgrade happened and the noble did
	/// not yet updated its version in storage, this will return a
	/// different(the previous, seen from the time of calling) version.
	///
	/// See [`NobleVersion`] for more information.
	///
	/// # Note
	///
	/// If there was no previous version of the noble stored in the state,
	/// this function returns `None`.
	fn storage_version() -> Option<NobleVersion>;
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn on_initialize_and_on_runtime_upgrade_weight_merge_works() {
		struct Test;
		impl OnInitialize<u8> for Test {
			fn on_initialize(_n: u8) -> crate::weights::Weight {
				10
			}
		}
		impl OnRuntimeUpgrade for Test {
			fn on_runtime_upgrade() -> crate::weights::Weight {
				20
			}
		}

		assert_eq!(<(Test, Test)>::on_initialize(0), 20);
		assert_eq!(<(Test, Test)>::on_runtime_upgrade(), 40);
	}

	#[test]
	fn check_noble_version_ordering() {
		let version = NobleVersion::new(1, 0, 0);
		assert!(version > NobleVersion::new(0, 1, 2));
		assert!(version == NobleVersion::new(1, 0, 0));
		assert!(version < NobleVersion::new(1, 0, 1));
		assert!(version < NobleVersion::new(1, 1, 0));

		let version = NobleVersion::new(2, 50, 50);
		assert!(version < NobleVersion::new(2, 50, 51));
		assert!(version > NobleVersion::new(2, 49, 51));
		assert!(version < NobleVersion::new(3, 49, 51));
	}
}