// SPDX-License-Identifier: CC0-1.0

//! Bitcoin script opcodes.
//!
//! Bitcoin's script uses a stack-based assembly language. This module defines
//! all of the opcodes for that language.

#![allow(non_camel_case_types)]

use core::fmt;

use internals::debug_from_display;

#[cfg(feature = "serde")]
use crate::prelude::ToString;

/// A script Opcode.
///
/// We do not implement Ord on this type because there is no natural ordering on opcodes, but there
/// may appear to be one (e.g. because all the push opcodes appear in a consecutive block) and we
/// don't want to encourage subtly buggy code. Please use [`Opcode::classify`] to distinguish different
/// types of opcodes.
///
/// <details>
///   <summary>Example of Core bug caused by assuming ordering</summary>
///
///   Bitcoin Core's `IsPushOnly` considers `OP_RESERVED` to be a "push code", allowing this opcode
///   in contexts where only pushes are supposed to be allowed.
/// </details>
#[derive(Copy, Clone, PartialEq, Eq)]
pub struct Opcode {
    code: u8,
}

use self::all::*;

macro_rules! all_opcodes {
    ($($op:ident => $val:expr, $doc:expr);*) => {
        /// Enables wildcard imports to bring into scope all opcodes and nothing else.
        ///
        /// The `all` module is provided so one can use a wildcard import `use bitcoin::opcodes::all::*` to
        /// get all the `OP_FOO` opcodes without getting other types defined in `opcodes` (e.g. `Opcode`, `Class`).
        ///
        /// This module is guaranteed to never contain anything except opcode constants and all opcode
        /// constants are guaranteed to begin with OP_.
        pub mod all {
            use super::Opcode;
            $(
                #[doc = $doc]
                pub const $op: Opcode = Opcode { code: $val};
            )*
        }

        /// Push an empty array onto the stack.
        pub static OP_0: Opcode = OP_PUSHBYTES_0;
        /// Empty stack is also FALSE.
        pub static OP_FALSE: Opcode = OP_PUSHBYTES_0;
        /// Number 1 is also TRUE.
        pub static OP_TRUE: Opcode = OP_PUSHNUM_1;
        /// Previously called OP_NOP2.
        pub static OP_NOP2: Opcode = OP_CLTV;
        /// Previously called OP_NOP3.
        pub static OP_NOP3: Opcode = OP_CSV;

        impl fmt::Display for Opcode {
            fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
                 match *self {
                   $(
                        $op => core::fmt::Display::fmt(stringify!($op), f),
                    )+
                }
            }
        }
    }
}

all_opcodes! {
    OP_PUSHBYTES_0 => 0x00, "Push an empty array onto the stack.";
    OP_PUSHBYTES_1 => 0x01, "Push the next byte as an array onto the stack.";
    OP_PUSHBYTES_2 => 0x02, "Push the next 2 bytes as an array onto the stack.";
    OP_PUSHBYTES_3 => 0x03, "Push the next 3 bytes as an array onto the stack.";
    OP_PUSHBYTES_4 => 0x04, "Push the next 4 bytes as an array onto the stack.";
    OP_PUSHBYTES_5 => 0x05, "Push the next 5 bytes as an array onto the stack.";
    OP_PUSHBYTES_6 => 0x06, "Push the next 6 bytes as an array onto the stack.";
    OP_PUSHBYTES_7 => 0x07, "Push the next 7 bytes as an array onto the stack.";
    OP_PUSHBYTES_8 => 0x08, "Push the next 8 bytes as an array onto the stack.";
    OP_PUSHBYTES_9 => 0x09, "Push the next 9 bytes as an array onto the stack.";
    OP_PUSHBYTES_10 => 0x0a, "Push the next 10 bytes as an array onto the stack.";
    OP_PUSHBYTES_11 => 0x0b, "Push the next 11 bytes as an array onto the stack.";
    OP_PUSHBYTES_12 => 0x0c, "Push the next 12 bytes as an array onto the stack.";
    OP_PUSHBYTES_13 => 0x0d, "Push the next 13 bytes as an array onto the stack.";
    OP_PUSHBYTES_14 => 0x0e, "Push the next 14 bytes as an array onto the stack.";
    OP_PUSHBYTES_15 => 0x0f, "Push the next 15 bytes as an array onto the stack.";
    OP_PUSHBYTES_16 => 0x10, "Push the next 16 bytes as an array onto the stack.";
    OP_PUSHBYTES_17 => 0x11, "Push the next 17 bytes as an array onto the stack.";
    OP_PUSHBYTES_18 => 0x12, "Push the next 18 bytes as an array onto the stack.";
    OP_PUSHBYTES_19 => 0x13, "Push the next 19 bytes as an array onto the stack.";
    OP_PUSHBYTES_20 => 0x14, "Push the next 20 bytes as an array onto the stack.";
    OP_PUSHBYTES_21 => 0x15, "Push the next 21 bytes as an array onto the stack.";
    OP_PUSHBYTES_22 => 0x16, "Push the next 22 bytes as an array onto the stack.";
    OP_PUSHBYTES_23 => 0x17, "Push the next 23 bytes as an array onto the stack.";
    OP_PUSHBYTES_24 => 0x18, "Push the next 24 bytes as an array onto the stack.";
    OP_PUSHBYTES_25 => 0x19, "Push the next 25 bytes as an array onto the stack.";
    OP_PUSHBYTES_26 => 0x1a, "Push the next 26 bytes as an array onto the stack.";
    OP_PUSHBYTES_27 => 0x1b, "Push the next 27 bytes as an array onto the stack.";
    OP_PUSHBYTES_28 => 0x1c, "Push the next 28 bytes as an array onto the stack.";
    OP_PUSHBYTES_29 => 0x1d, "Push the next 29 bytes as an array onto the stack.";
    OP_PUSHBYTES_30 => 0x1e, "Push the next 30 bytes as an array onto the stack.";
    OP_PUSHBYTES_31 => 0x1f, "Push the next 31 bytes as an array onto the stack.";
    OP_PUSHBYTES_32 => 0x20, "Push the next 32 bytes as an array onto the stack.";
    OP_PUSHBYTES_33 => 0x21, "Push the next 33 bytes as an array onto the stack.";
    OP_PUSHBYTES_34 => 0x22, "Push the next 34 bytes as an array onto the stack.";
    OP_PUSHBYTES_35 => 0x23, "Push the next 35 bytes as an array onto the stack.";
    OP_PUSHBYTES_36 => 0x24, "Push the next 36 bytes as an array onto the stack.";
    OP_PUSHBYTES_37 => 0x25, "Push the next 37 bytes as an array onto the stack.";
    OP_PUSHBYTES_38 => 0x26, "Push the next 38 bytes as an array onto the stack.";
    OP_PUSHBYTES_39 => 0x27, "Push the next 39 bytes as an array onto the stack.";
    OP_PUSHBYTES_40 => 0x28, "Push the next 40 bytes as an array onto the stack.";
    OP_PUSHBYTES_41 => 0x29, "Push the next 41 bytes as an array onto the stack.";
    OP_PUSHBYTES_42 => 0x2a, "Push the next 42 bytes as an array onto the stack.";
    OP_PUSHBYTES_43 => 0x2b, "Push the next 43 bytes as an array onto the stack.";
    OP_PUSHBYTES_44 => 0x2c, "Push the next 44 bytes as an array onto the stack.";
    OP_PUSHBYTES_45 => 0x2d, "Push the next 45 bytes as an array onto the stack.";
    OP_PUSHBYTES_46 => 0x2e, "Push the next 46 bytes as an array onto the stack.";
    OP_PUSHBYTES_47 => 0x2f, "Push the next 47 bytes as an array onto the stack.";
    OP_PUSHBYTES_48 => 0x30, "Push the next 48 bytes as an array onto the stack.";
    OP_PUSHBYTES_49 => 0x31, "Push the next 49 bytes as an array onto the stack.";
    OP_PUSHBYTES_50 => 0x32, "Push the next 50 bytes as an array onto the stack.";
    OP_PUSHBYTES_51 => 0x33, "Push the next 51 bytes as an array onto the stack.";
    OP_PUSHBYTES_52 => 0x34, "Push the next 52 bytes as an array onto the stack.";
    OP_PUSHBYTES_53 => 0x35, "Push the next 53 bytes as an array onto the stack.";
    OP_PUSHBYTES_54 => 0x36, "Push the next 54 bytes as an array onto the stack.";
    OP_PUSHBYTES_55 => 0x37, "Push the next 55 bytes as an array onto the stack.";
    OP_PUSHBYTES_56 => 0x38, "Push the next 56 bytes as an array onto the stack.";
    OP_PUSHBYTES_57 => 0x39, "Push the next 57 bytes as an array onto the stack.";
    OP_PUSHBYTES_58 => 0x3a, "Push the next 58 bytes as an array onto the stack.";
    OP_PUSHBYTES_59 => 0x3b, "Push the next 59 bytes as an array onto the stack.";
    OP_PUSHBYTES_60 => 0x3c, "Push the next 60 bytes as an array onto the stack.";
    OP_PUSHBYTES_61 => 0x3d, "Push the next 61 bytes as an array onto the stack.";
    OP_PUSHBYTES_62 => 0x3e, "Push the next 62 bytes as an array onto the stack.";
    OP_PUSHBYTES_63 => 0x3f, "Push the next 63 bytes as an array onto the stack.";
    OP_PUSHBYTES_64 => 0x40, "Push the next 64 bytes as an array onto the stack.";
    OP_PUSHBYTES_65 => 0x41, "Push the next 65 bytes as an array onto the stack.";
    OP_PUSHBYTES_66 => 0x42, "Push the next 66 bytes as an array onto the stack.";
    OP_PUSHBYTES_67 => 0x43, "Push the next 67 bytes as an array onto the stack.";
    OP_PUSHBYTES_68 => 0x44, "Push the next 68 bytes as an array onto the stack.";
    OP_PUSHBYTES_69 => 0x45, "Push the next 69 bytes as an array onto the stack.";
    OP_PUSHBYTES_70 => 0x46, "Push the next 70 bytes as an array onto the stack.";
    OP_PUSHBYTES_71 => 0x47, "Push the next 71 bytes as an array onto the stack.";
    OP_PUSHBYTES_72 => 0x48, "Push the next 72 bytes as an array onto the stack.";
    OP_PUSHBYTES_73 => 0x49, "Push the next 73 bytes as an array onto the stack.";
    OP_PUSHBYTES_74 => 0x4a, "Push the next 74 bytes as an array onto the stack.";
    OP_PUSHBYTES_75 => 0x4b, "Push the next 75 bytes as an array onto the stack.";
    OP_PUSHDATA1 => 0x4c, "Read the next byte as N; push the next N bytes as an array onto the stack.";
    OP_PUSHDATA2 => 0x4d, "Read the next 2 bytes as N; push the next N bytes as an array onto the stack.";
    OP_PUSHDATA4 => 0x4e, "Read the next 4 bytes as N; push the next N bytes as an array onto the stack.";
    OP_PUSHNUM_NEG1 => 0x4f, "Push the array `0x81` onto the stack.";
    OP_RESERVED => 0x50, "Synonym for OP_RETURN.";
    OP_PUSHNUM_1 => 0x51, "Push the array `0x01` onto the stack.";
    OP_PUSHNUM_2 => 0x52, "Push the array `0x02` onto the stack.";
    OP_PUSHNUM_3 => 0x53, "Push the array `0x03` onto the stack.";
    OP_PUSHNUM_4 => 0x54, "Push the array `0x04` onto the stack.";
    OP_PUSHNUM_5 => 0x55, "Push the array `0x05` onto the stack.";
    OP_PUSHNUM_6 => 0x56, "Push the array `0x06` onto the stack.";
    OP_PUSHNUM_7 => 0x57, "Push the array `0x07` onto the stack.";
    OP_PUSHNUM_8 => 0x58, "Push the array `0x08` onto the stack.";
    OP_PUSHNUM_9 => 0x59, "Push the array `0x09` onto the stack.";
    OP_PUSHNUM_10 => 0x5a, "Push the array `0x0a` onto the stack.";
    OP_PUSHNUM_11 => 0x5b, "Push the array `0x0b` onto the stack.";
    OP_PUSHNUM_12 => 0x5c, "Push the array `0x0c` onto the stack.";
    OP_PUSHNUM_13 => 0x5d, "Push the array `0x0d` onto the stack.";
    OP_PUSHNUM_14 => 0x5e, "Push the array `0x0e` onto the stack.";
    OP_PUSHNUM_15 => 0x5f, "Push the array `0x0f` onto the stack.";
    OP_PUSHNUM_16 => 0x60, "Push the array `0x10` onto the stack.";
    OP_NOP => 0x61, "Does nothing.";
    OP_VER => 0x62, "Synonym for OP_RETURN.";
    OP_IF => 0x63, "Pop and execute the next statements if a nonzero element was popped.";
    OP_NOTIF => 0x64, "Pop and execute the next statements if a zero element was popped.";
    OP_VERIF => 0x65, "Fail the script unconditionally, does not even need to be executed.";
    OP_VERNOTIF => 0x66, "Fail the script unconditionally, does not even need to be executed.";
    OP_ELSE => 0x67, "Execute statements if those after the previous OP_IF were not, and vice-versa. \
             If there is no previous OP_IF, this acts as a RETURN.";
    OP_ENDIF => 0x68, "Pop and execute the next statements if a zero element was popped.";
    OP_VERIFY => 0x69, "If the top value is zero or the stack is empty, fail; otherwise, pop the stack.";
    OP_RETURN => 0x6a, "Fail the script immediately. (Must be executed.).";
    OP_TOALTSTACK => 0x6b, "Pop one element from the main stack onto the alt stack.";
    OP_FROMALTSTACK => 0x6c, "Pop one element from the alt stack onto the main stack.";
    OP_2DROP => 0x6d, "Drops the top two stack items.";
    OP_2DUP => 0x6e, "Duplicates the top two stack items as AB -> ABAB.";
    OP_3DUP => 0x6f, "Duplicates the two three stack items as ABC -> ABCABC.";
    OP_2OVER => 0x70, "Copies the two stack items of items two spaces back to the front, as xxAB -> ABxxAB.";
    OP_2ROT => 0x71, "Moves the two stack items four spaces back to the front, as xxxxAB -> ABxxxx.";
    OP_2SWAP => 0x72, "Swaps the top two pairs, as ABCD -> CDAB.";
    OP_IFDUP => 0x73, "Duplicate the top stack element unless it is zero.";
    OP_DEPTH => 0x74, "Push the current number of stack items onto the stack.";
    OP_DROP => 0x75, "Drops the top stack item.";
    OP_DUP => 0x76, "Duplicates the top stack item.";
    OP_NIP => 0x77, "Drops the second-to-top stack item.";
    OP_OVER => 0x78, "Copies the second-to-top stack item, as xA -> AxA.";
    OP_PICK => 0x79, "Pop the top stack element as N. Copy the Nth stack element to the top.";
    OP_ROLL => 0x7a, "Pop the top stack element as N. Move the Nth stack element to the top.";
    OP_ROT => 0x7b, "Rotate the top three stack items, as [top next1 next2] -> [next2 top next1].";
    OP_SWAP => 0x7c, "Swap the top two stack items.";
    OP_TUCK => 0x7d, "Copy the top stack item to before the second item, as [top next] -> [top next top].";
    OP_CAT => 0x7e, "Fail the script unconditionally, does not even need to be executed.";
    OP_SUBSTR => 0x7f, "Fail the script unconditionally, does not even need to be executed.";
    OP_LEFT => 0x80, "Fail the script unconditionally, does not even need to be executed.";
    OP_RIGHT => 0x81, "Fail the script unconditionally, does not even need to be executed.";
    OP_SIZE => 0x82, "Pushes the length of the top stack item onto the stack.";
    OP_INVERT => 0x83, "Fail the script unconditionally, does not even need to be executed.";
    OP_AND => 0x84, "Fail the script unconditionally, does not even need to be executed.";
    OP_OR => 0x85, "Fail the script unconditionally, does not even need to be executed.";
    OP_XOR => 0x86, "Fail the script unconditionally, does not even need to be executed.";
    OP_EQUAL => 0x87, "Pushes 1 if the inputs are exactly equal, 0 otherwise.";
    OP_EQUALVERIFY => 0x88, "Returns success if the inputs are exactly equal, failure otherwise.";
    OP_RESERVED1 => 0x89, "Synonym for OP_RETURN.";
    OP_RESERVED2 => 0x8a, "Synonym for OP_RETURN.";
    OP_1ADD => 0x8b, "Increment the top stack element in place.";
    OP_1SUB => 0x8c, "Decrement the top stack element in place.";
    OP_2MUL => 0x8d, "Fail the script unconditionally, does not even need to be executed.";
    OP_2DIV => 0x8e, "Fail the script unconditionally, does not even need to be executed.";
    OP_NEGATE => 0x8f, "Multiply the top stack item by -1 in place.";
    OP_ABS => 0x90, "Absolute value the top stack item in place.";
    OP_NOT => 0x91, "Map 0 to 1 and everything else to 0, in place.";
    OP_0NOTEQUAL => 0x92, "Map 0 to 0 and everything else to 1, in place.";
    OP_ADD => 0x93, "Pop two stack items and push their sum.";
    OP_SUB => 0x94, "Pop two stack items and push the second minus the top.";
    OP_MUL => 0x95, "Fail the script unconditionally, does not even need to be executed.";
    OP_DIV => 0x96, "Fail the script unconditionally, does not even need to be executed.";
    OP_MOD => 0x97, "Fail the script unconditionally, does not even need to be executed.";
    OP_LSHIFT => 0x98, "Fail the script unconditionally, does not even need to be executed.";
    OP_RSHIFT => 0x99, "Fail the script unconditionally, does not even need to be executed.";
    OP_BOOLAND => 0x9a, "Pop the top two stack items and push 1 if both are nonzero, else push 0.";
    OP_BOOLOR => 0x9b, "Pop the top two stack items and push 1 if either is nonzero, else push 0.";
    OP_NUMEQUAL => 0x9c, "Pop the top two stack items and push 1 if both are numerically equal, else push 0.";
    OP_NUMEQUALVERIFY => 0x9d, "Pop the top two stack items and return success if both are numerically equal, else return failure.";
    OP_NUMNOTEQUAL => 0x9e, "Pop the top two stack items and push 0 if both are numerically equal, else push 1.";
    OP_LESSTHAN  => 0x9f, "Pop the top two items; push 1 if the second is less than the top, 0 otherwise.";
    OP_GREATERTHAN  => 0xa0, "Pop the top two items; push 1 if the second is greater than the top, 0 otherwise.";
    OP_LESSTHANOREQUAL  => 0xa1, "Pop the top two items; push 1 if the second is <= the top, 0 otherwise.";
    OP_GREATERTHANOREQUAL  => 0xa2, "Pop the top two items; push 1 if the second is >= the top, 0 otherwise.";
    OP_MIN => 0xa3, "Pop the top two items; push the smaller.";
    OP_MAX => 0xa4, "Pop the top two items; push the larger.";
    OP_WITHIN => 0xa5, "Pop the top three items; if the top is >= the second and < the third, push 1, otherwise push 0.";
    OP_RIPEMD160 => 0xa6, "Pop the top stack item and push its RIPEMD160 hash.";
    OP_SHA1 => 0xa7, "Pop the top stack item and push its SHA1 hash.";
    OP_SHA256 => 0xa8, "Pop the top stack item and push its SHA256 hash.";
    OP_HASH160 => 0xa9, "Pop the top stack item and push its RIPEMD(SHA256) hash.";
    OP_HASH256 => 0xaa, "Pop the top stack item and push its SHA256(SHA256) hash.";
    OP_CODESEPARATOR => 0xab, "Ignore this and everything preceding when deciding what to sign when signature-checking.";
    OP_CHECKSIG => 0xac, "<https://en.bitcoin.it/wiki/OP_CHECKSIG> pushing 1/0 for success/failure.";
    OP_CHECKSIGVERIFY => 0xad, "<https://en.bitcoin.it/wiki/OP_CHECKSIG> returning success/failure.";
    OP_CHECKMULTISIG => 0xae, "Pop N, N pubkeys, M, M signatures, a dummy (due to bug in reference code), \
                      and verify that all M signatures are valid. Push 1 for 'all valid', 0 otherwise.";
    OP_CHECKMULTISIGVERIFY => 0xaf, "Like the above but return success/failure.";
    OP_NOP1 => 0xb0, "Does nothing.";
    OP_CLTV => 0xb1, "<https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki>";
    OP_CSV => 0xb2, "<https://github.com/bitcoin/bips/blob/master/bip-0112.mediawiki>";
    OP_NOP4 => 0xb3, "Does nothing.";
    OP_NOP5 => 0xb4, "Does nothing.";
    OP_NOP6 => 0xb5, "Does nothing.";
    OP_NOP7 => 0xb6, "Does nothing.";
    OP_NOP8 => 0xb7, "Does nothing.";
    OP_NOP9 => 0xb8, "Does nothing.";
    OP_NOP10 => 0xb9, "Does nothing.";
    // Every other opcode acts as OP_RETURN
    OP_CHECKSIGADD => 0xba, "OP_CHECKSIGADD post tapscript.";
    OP_RETURN_187 => 0xbb, "Synonym for OP_RETURN.";
    OP_RETURN_188 => 0xbc, "Synonym for OP_RETURN.";
    OP_RETURN_189 => 0xbd, "Synonym for OP_RETURN.";
    OP_RETURN_190 => 0xbe, "Synonym for OP_RETURN.";
    OP_RETURN_191 => 0xbf, "Synonym for OP_RETURN.";
    OP_RETURN_192 => 0xc0, "Synonym for OP_RETURN.";
    OP_RETURN_193 => 0xc1, "Synonym for OP_RETURN.";
    OP_RETURN_194 => 0xc2, "Synonym for OP_RETURN.";
    OP_RETURN_195 => 0xc3, "Synonym for OP_RETURN.";
    OP_RETURN_196 => 0xc4, "Synonym for OP_RETURN.";
    OP_RETURN_197 => 0xc5, "Synonym for OP_RETURN.";
    OP_RETURN_198 => 0xc6, "Synonym for OP_RETURN.";
    OP_RETURN_199 => 0xc7, "Synonym for OP_RETURN.";
    OP_RETURN_200 => 0xc8, "Synonym for OP_RETURN.";
    OP_RETURN_201 => 0xc9, "Synonym for OP_RETURN.";
    OP_RETURN_202 => 0xca, "Synonym for OP_RETURN.";
    OP_RETURN_203 => 0xcb, "Synonym for OP_RETURN.";
    OP_RETURN_204 => 0xcc, "Synonym for OP_RETURN.";
    OP_RETURN_205 => 0xcd, "Synonym for OP_RETURN.";
    OP_RETURN_206 => 0xce, "Synonym for OP_RETURN.";
    OP_RETURN_207 => 0xcf, "Synonym for OP_RETURN.";
    OP_RETURN_208 => 0xd0, "Synonym for OP_RETURN.";
    OP_RETURN_209 => 0xd1, "Synonym for OP_RETURN.";
    OP_RETURN_210 => 0xd2, "Synonym for OP_RETURN.";
    OP_RETURN_211 => 0xd3, "Synonym for OP_RETURN.";
    OP_RETURN_212 => 0xd4, "Synonym for OP_RETURN.";
    OP_RETURN_213 => 0xd5, "Synonym for OP_RETURN.";
    OP_RETURN_214 => 0xd6, "Synonym for OP_RETURN.";
    OP_RETURN_215 => 0xd7, "Synonym for OP_RETURN.";
    OP_RETURN_216 => 0xd8, "Synonym for OP_RETURN.";
    OP_RETURN_217 => 0xd9, "Synonym for OP_RETURN.";
    OP_RETURN_218 => 0xda, "Synonym for OP_RETURN.";
    OP_RETURN_219 => 0xdb, "Synonym for OP_RETURN.";
    OP_RETURN_220 => 0xdc, "Synonym for OP_RETURN.";
    OP_RETURN_221 => 0xdd, "Synonym for OP_RETURN.";
    OP_RETURN_222 => 0xde, "Synonym for OP_RETURN.";
    OP_RETURN_223 => 0xdf, "Synonym for OP_RETURN.";
    OP_RETURN_224 => 0xe0, "Synonym for OP_RETURN.";
    OP_RETURN_225 => 0xe1, "Synonym for OP_RETURN.";
    OP_RETURN_226 => 0xe2, "Synonym for OP_RETURN.";
    OP_RETURN_227 => 0xe3, "Synonym for OP_RETURN.";
    OP_RETURN_228 => 0xe4, "Synonym for OP_RETURN.";
    OP_RETURN_229 => 0xe5, "Synonym for OP_RETURN.";
    OP_RETURN_230 => 0xe6, "Synonym for OP_RETURN.";
    OP_RETURN_231 => 0xe7, "Synonym for OP_RETURN.";
    OP_RETURN_232 => 0xe8, "Synonym for OP_RETURN.";
    OP_RETURN_233 => 0xe9, "Synonym for OP_RETURN.";
    OP_RETURN_234 => 0xea, "Synonym for OP_RETURN.";
    OP_RETURN_235 => 0xeb, "Synonym for OP_RETURN.";
    OP_RETURN_236 => 0xec, "Synonym for OP_RETURN.";
    OP_RETURN_237 => 0xed, "Synonym for OP_RETURN.";
    OP_RETURN_238 => 0xee, "Synonym for OP_RETURN.";
    OP_RETURN_239 => 0xef, "Synonym for OP_RETURN.";
    OP_RETURN_240 => 0xf0, "Synonym for OP_RETURN.";
    OP_RETURN_241 => 0xf1, "Synonym for OP_RETURN.";
    OP_RETURN_242 => 0xf2, "Synonym for OP_RETURN.";
    OP_RETURN_243 => 0xf3, "Synonym for OP_RETURN.";
    OP_RETURN_244 => 0xf4, "Synonym for OP_RETURN.";
    OP_RETURN_245 => 0xf5, "Synonym for OP_RETURN.";
    OP_RETURN_246 => 0xf6, "Synonym for OP_RETURN.";
    OP_RETURN_247 => 0xf7, "Synonym for OP_RETURN.";
    OP_RETURN_248 => 0xf8, "Synonym for OP_RETURN.";
    OP_RETURN_249 => 0xf9, "Synonym for OP_RETURN.";
    OP_RETURN_250 => 0xfa, "Synonym for OP_RETURN.";
    OP_RETURN_251 => 0xfb, "Synonym for OP_RETURN.";
    OP_RETURN_252 => 0xfc, "Synonym for OP_RETURN.";
    OP_RETURN_253 => 0xfd, "Synonym for OP_RETURN.";
    OP_RETURN_254 => 0xfe, "Synonym for OP_RETURN.";
    OP_INVALIDOPCODE => 0xff, "Synonym for OP_RETURN."
}

/// Classification context for the opcode.
///
/// Some opcodes like [`OP_RESERVED`] abort the script in `ClassifyContext::Legacy` context,
/// but will act as `OP_SUCCESSx` in `ClassifyContext::TapScript` (see BIP342 for full list).
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum ClassifyContext {
    /// Opcode used in tapscript context.
    TapScript,
    /// Opcode used in legacy context.
    Legacy,
}

impl Opcode {
    /// Classifies an Opcode into a broad class.
    #[inline]
    pub fn classify(self, ctx: ClassifyContext) -> Class {
        match (self, ctx) {
            // 3 opcodes illegal in all contexts
            (OP_VERIF, _) | (OP_VERNOTIF, _) | (OP_INVALIDOPCODE, _) => Class::IllegalOp,

            // 15 opcodes illegal in Legacy context
            #[rustfmt::skip]
            (OP_CAT, ctx) | (OP_SUBSTR, ctx)
            | (OP_LEFT, ctx) | (OP_RIGHT, ctx)
            | (OP_INVERT, ctx)
            | (OP_AND, ctx) | (OP_OR, ctx) | (OP_XOR, ctx)
            | (OP_2MUL, ctx) | (OP_2DIV, ctx)
            | (OP_MUL, ctx) | (OP_DIV, ctx) | (OP_MOD, ctx)
            | (OP_LSHIFT, ctx) | (OP_RSHIFT, ctx) if ctx == ClassifyContext::Legacy => Class::IllegalOp,

            // 87 opcodes of SuccessOp class only in TapScript context
            (op, ClassifyContext::TapScript)
                if op.code == 80
                    || op.code == 98
                    || (op.code >= 126 && op.code <= 129)
                    || (op.code >= 131 && op.code <= 134)
                    || (op.code >= 137 && op.code <= 138)
                    || (op.code >= 141 && op.code <= 142)
                    || (op.code >= 149 && op.code <= 153)
                    || (op.code >= 187 && op.code <= 254) =>
            {
                Class::SuccessOp
            }

            // 11 opcodes of NoOp class
            (OP_NOP, _) => Class::NoOp,
            (op, _) if op.code >= OP_NOP1.code && op.code <= OP_NOP10.code => Class::NoOp,

            // 1 opcode for `OP_RETURN`
            (OP_RETURN, _) => Class::ReturnOp,

            // 4 opcodes operating equally to `OP_RETURN` only in Legacy context
            (OP_RESERVED, ctx) | (OP_RESERVED1, ctx) | (OP_RESERVED2, ctx) | (OP_VER, ctx)
                if ctx == ClassifyContext::Legacy =>
            {
                Class::ReturnOp
            }

            // 71 opcodes operating equally to `OP_RETURN` only in Legacy context
            (op, ClassifyContext::Legacy) if op.code >= OP_CHECKSIGADD.code => Class::ReturnOp,

            // 2 opcodes operating equally to `OP_RETURN` only in TapScript context
            (OP_CHECKMULTISIG, ClassifyContext::TapScript)
            | (OP_CHECKMULTISIGVERIFY, ClassifyContext::TapScript) => Class::ReturnOp,

            // 1 opcode of PushNum class
            (OP_PUSHNUM_NEG1, _) => Class::PushNum(-1),

            // 16 opcodes of PushNum class
            (op, _) if op.code >= OP_PUSHNUM_1.code && op.code <= OP_PUSHNUM_16.code => {
                Class::PushNum(1 + self.code as i32 - OP_PUSHNUM_1.code as i32)
            }

            // 76 opcodes of PushBytes class
            (op, _) if op.code <= OP_PUSHBYTES_75.code => Class::PushBytes(self.code as u32),

            // opcodes of Ordinary class: 61 for Legacy and 60 for TapScript context
            (_, _) => Class::Ordinary(Ordinary::with(self)),
        }
    }

    /// Encodes [`Opcode`] as a byte.
    #[inline]
    pub const fn to_u8(self) -> u8 {
        self.code
    }

    /// Encodes PUSHNUM [`Opcode`] as a `u8` representing its number (1-16).
    ///
    /// Does not convert `OP_FALSE` to 0. Only `1` to `OP_PUSHNUM_16` are covered.
    ///
    /// # Returns
    ///
    /// Returns `None` if `self` is not a PUSHNUM.
    #[inline]
    pub const fn decode_pushnum(self) -> Option<u8> {
        const START: u8 = OP_PUSHNUM_1.code;
        const END: u8 = OP_PUSHNUM_16.code;
        match self.code {
            START..=END => Some(self.code - START + 1),
            _ => None,
        }
    }
}

impl From<u8> for Opcode {
    #[inline]
    fn from(b: u8) -> Opcode {
        Opcode { code: b }
    }
}

debug_from_display!(Opcode);

#[cfg(feature = "serde")]
impl serde::Serialize for Opcode {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
    {
        serializer.serialize_str(&self.to_string())
    }
}

/// Broad categories of opcodes with similar behavior.
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub enum Class {
    /// Pushes the given number onto the stack.
    PushNum(i32),
    /// Pushes the given number of bytes onto the stack.
    PushBytes(u32),
    /// Fails the script if executed.
    ReturnOp,
    /// Succeeds the script even if not executed.
    SuccessOp,
    /// Fails the script even if not executed.
    IllegalOp,
    /// Does nothing.
    NoOp,
    /// Any opcode not covered above.
    Ordinary(Ordinary),
}

macro_rules! ordinary_opcode {
    ($($op:ident),*) => (
        #[repr(u8)]
        #[doc(hidden)]
        #[derive(Copy, Clone, PartialEq, Eq, Debug)]
        pub enum Ordinary {
            $( $op = $op.code ),*
        }

        impl fmt::Display for Ordinary {
            fn fmt(&self, f: &mut fmt::Formatter) -> core::fmt::Result {
                match *self {
                   $(Ordinary::$op => { f.pad(stringify!($op)) }),*
                }
            }
        }

        impl Ordinary {
            fn with(b: Opcode) -> Self {
                match b {
                    $( $op => { Ordinary::$op } ),*
                    _ => unreachable!("construction of `Ordinary` type from non-ordinary opcode {}", b),
                }
            }

            /// Try to create a [`Ordinary`] from an [`Opcode`].
            pub fn from_opcode(b: Opcode) -> Option<Self> {
                match b {
                    $( $op => { Some(Ordinary::$op) } ),*
                    _ => None,
                }
            }
        }
    );
}

// "Ordinary" opcodes -- should be 61 of these
ordinary_opcode! {
    // pushdata
    OP_PUSHDATA1, OP_PUSHDATA2, OP_PUSHDATA4,
    // control flow
    OP_IF, OP_NOTIF, OP_ELSE, OP_ENDIF, OP_VERIFY,
    // stack
    OP_TOALTSTACK, OP_FROMALTSTACK,
    OP_2DROP, OP_2DUP, OP_3DUP, OP_2OVER, OP_2ROT, OP_2SWAP,
    OP_DROP, OP_DUP, OP_NIP, OP_OVER, OP_PICK, OP_ROLL, OP_ROT, OP_SWAP, OP_TUCK,
    OP_IFDUP, OP_DEPTH, OP_SIZE,
    // equality
    OP_EQUAL, OP_EQUALVERIFY,
    // arithmetic
    OP_1ADD, OP_1SUB, OP_NEGATE, OP_ABS, OP_NOT, OP_0NOTEQUAL,
    OP_ADD, OP_SUB, OP_BOOLAND, OP_BOOLOR,
    OP_NUMEQUAL, OP_NUMEQUALVERIFY, OP_NUMNOTEQUAL, OP_LESSTHAN,
    OP_GREATERTHAN, OP_LESSTHANOREQUAL, OP_GREATERTHANOREQUAL,
    OP_MIN, OP_MAX, OP_WITHIN,
    // crypto
    OP_RIPEMD160, OP_SHA1, OP_SHA256, OP_HASH160, OP_HASH256,
    OP_CODESEPARATOR, OP_CHECKSIG, OP_CHECKSIGVERIFY,
    OP_CHECKMULTISIG, OP_CHECKMULTISIGVERIFY,
    OP_CHECKSIGADD
}

impl Ordinary {
    /// Encodes [`Opcode`] as a byte.
    #[inline]
    pub fn to_u8(self) -> u8 {
        self as u8
    }
}