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

use crate::{Bytes32, BytesImpl};
use chia_streamable_macro::streamable;
use clvm_traits::{
    clvm_list, destructure_list, match_list, ClvmDecoder, ClvmEncoder, FromClvm, FromClvmError,
    ToClvm, ToClvmError,
};
use sha2::{Digest, Sha256};

#[cfg(feature = "py-bindings")]
use pyo3::prelude::*;

#[streamable]
#[derive(Copy)]
pub struct Coin {
    parent_coin_info: Bytes32,
    puzzle_hash: Bytes32,
    amount: u64,
}

impl Coin {
    pub fn coin_id(&self) -> Bytes32 {
        let mut hasher = Sha256::new();
        hasher.update(self.parent_coin_info);
        hasher.update(self.puzzle_hash);

        let amount_bytes = self.amount.to_be_bytes();
        if self.amount >= 0x8000000000000000_u64 {
            hasher.update([0_u8]);
            hasher.update(amount_bytes);
        } else {
            let start = match self.amount {
                n if n >= 0x80000000000000_u64 => 0,
                n if n >= 0x800000000000_u64 => 1,
                n if n >= 0x8000000000_u64 => 2,
                n if n >= 0x80000000_u64 => 3,
                n if n >= 0x800000_u64 => 4,
                n if n >= 0x8000_u64 => 5,
                n if n >= 0x80_u64 => 6,
                n if n > 0 => 7,
                _ => 8,
            };
            hasher.update(&amount_bytes[start..]);
        }

        let coin_id: [u8; 32] = hasher.finalize().as_slice().try_into().unwrap();
        Bytes32::new(coin_id)
    }
}

#[cfg(feature = "py-bindings")]
#[pymethods]
impl Coin {
    fn name<'p>(&self, py: pyo3::Python<'p>) -> pyo3::PyResult<&'p pyo3::types::PyBytes> {
        Ok(pyo3::types::PyBytes::new(py, &self.coin_id()))
    }
}

impl<N> ToClvm<N> for Coin {
    fn to_clvm(&self, encoder: &mut impl ClvmEncoder<Node = N>) -> Result<N, ToClvmError> {
        clvm_list!(self.parent_coin_info, self.puzzle_hash, self.amount).to_clvm(encoder)
    }
}

impl<N> FromClvm<N> for Coin {
    fn from_clvm(decoder: &impl ClvmDecoder<Node = N>, node: N) -> Result<Self, FromClvmError> {
        let destructure_list!(parent_coin_info, puzzle_hash, amount) =
            <match_list!(BytesImpl<32>, BytesImpl<32>, u64)>::from_clvm(decoder, node)?;
        Ok(Coin {
            parent_coin_info,
            puzzle_hash,
            amount,
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use clvmr::{
        serde::{node_from_bytes, node_to_bytes},
        Allocator,
    };
    use rstest::rstest;

    #[rstest]
    #[case(0, &[])]
    #[case(1, &[1])]
    #[case(0xff, &[0, 0xff])]
    #[case(0xffff, &[0, 0xff, 0xff])]
    #[case(0xffffff, &[0, 0xff, 0xff, 0xff])]
    #[case(0xffffffff, &[0, 0xff, 0xff, 0xff, 0xff])]
    #[case(0xffffffffff, &[0, 0xff, 0xff, 0xff, 0xff, 0xff])]
    #[case(0xffffffffffffffff, &[0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff])]
    #[case(0x7f, &[0x7f])]
    #[case(0x7fff, &[0x7f, 0xff])]
    #[case(0x7fffff, &[0x7f, 0xff, 0xff])]
    #[case(0x7fffffff, &[0x7f, 0xff, 0xff, 0xff])]
    #[case(0x7fffffffff, &[0x7f, 0xff, 0xff, 0xff, 0xff])]
    #[case(0x7fffffffffffffff, &[0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff])]
    #[case(0x80, &[0, 0x80])]
    #[case(0x8000, &[0, 0x80, 0x00])]
    #[case(0x800000, &[0, 0x80, 0x00, 0x00])]
    #[case(0x80000000, &[0, 0x80, 0x00, 0x00, 0x00])]
    #[case(0x8000000000, &[0, 0x80, 0x00, 0x00, 0x00, 0x00])]
    #[case(0x8000000000000000, &[0, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00])]
    fn coin_id(#[case] amount: u64, #[case] bytes: &[u8]) {
        let parent_coin = b"---foo---                       ";
        let puzzle_hash = b"---bar---                       ";

        let c = Coin::new(parent_coin.into(), puzzle_hash.into(), amount);
        let mut sha256 = Sha256::new();
        sha256.update(parent_coin);
        sha256.update(puzzle_hash);
        sha256.update(bytes);
        assert_eq!(c.coin_id().to_bytes(), &sha256.finalize() as &[u8]);
    }

    #[test]
    fn coin_roundtrip() {
        let a = &mut Allocator::new();
        let expected = "ffa09e144397decd2b831551f9710c17ae776d9c5a3ae5283c5f9747263fd1255381ffa0eff07522495060c066f66f32acc2a77e3a3e737aca8baea4d1a64ea4cdc13da9ff0180";
        let expected_bytes = hex::decode(expected).unwrap();

        let ptr = node_from_bytes(a, &expected_bytes).unwrap();
        let coin = Coin::from_clvm(a, ptr).unwrap();

        let round_trip = coin.to_clvm(a).unwrap();
        assert_eq!(expected, hex::encode(node_to_bytes(a, round_trip).unwrap()));
    }
}