use super::{FuncAddr, GlobalAddr, LabelAddr, LocalAddr, TableAddr, TypeAddr, ValType};

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum BlockArgs {
    Empty,
    Type(ValType),
    FuncType(u32),
}

/// Represents a memory immediate in a WebAssembly memory instruction.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub struct MemArg {
    pub align: u8,
    pub offset: u64,
}

type BrTableDefault = u32;
type BrTableLen = usize;
type EndOffset = usize;
type ElseOffset = usize;

#[derive(Debug, Clone, Copy, PartialEq)]
pub enum ConstInstruction {
    I32Const(i32),
    I64Const(i64),
    F32Const(f32),
    F64Const(f64),
    GlobalGet(GlobalAddr),
}

/// A WebAssembly Instruction
///
/// These are our own internal bytecode instructions so they may not match the spec exactly.
/// Wasm Bytecode can map to multiple of these instructions.
///
/// # Differences to the spec
/// * `br_table` stores the jump lables in the following `br_label` instructions to keep this enum small.
/// * Lables/Blocks: we store the label end offset in the instruction itself and
///   have seperate EndBlockFrame and EndFunc instructions to mark the end of a block or function.
///   This makes it easier to implement the label stack (we call it BlockFrameStack) iteratively.
///
/// See <https://webassembly.github.io/spec/core/binary/instructions.html>
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Instruction {
    // Custom Instructions
    BrLabel(LabelAddr),

    // Control Instructions
    // See <https://webassembly.github.io/spec/core/binary/instructions.html#control-instructions>
    Unreachable,
    Nop,
    Block(BlockArgs, EndOffset),
    Loop(BlockArgs, EndOffset),
    If(BlockArgs, Option<ElseOffset>, EndOffset),
    Else(EndOffset),
    EndBlockFrame,
    EndFunc,
    Br(LabelAddr),
    BrIf(LabelAddr),
    BrTable(BrTableDefault, BrTableLen), // has to be followed by multiple BrLabel instructions
    Return,
    Call(FuncAddr),
    CallIndirect(TypeAddr, TableAddr),

    // Parametric Instructions
    // See <https://webassembly.github.io/spec/core/binary/instructions.html#parametric-instructions>
    Drop,
    Select(Option<ValType>),

    // Variable Instructions
    // See <https://webassembly.github.io/spec/core/binary/instructions.html#variable-instructions>
    LocalGet(LocalAddr),
    LocalSet(LocalAddr),
    LocalTee(LocalAddr),
    GlobalGet(GlobalAddr),
    GlobalSet(GlobalAddr),

    // Memory Instructions
    I32Load(MemArg),
    I64Load(MemArg),
    F32Load(MemArg),
    F64Load(MemArg),
    I32Load8S(MemArg),
    I32Load8U(MemArg),
    I32Load16S(MemArg),
    I32Load16U(MemArg),
    I64Load8S(MemArg),
    I64Load8U(MemArg),
    I64Load16S(MemArg),
    I64Load16U(MemArg),
    I64Load32S(MemArg),
    I64Load32U(MemArg),
    I32Store(MemArg),
    I64Store(MemArg),
    F32Store(MemArg),
    F64Store(MemArg),
    I32Store8(MemArg),
    I32Store16(MemArg),
    I64Store8(MemArg),
    I64Store16(MemArg),
    I64Store32(MemArg),
    MemorySize,
    MemoryGrow,

    // Constants
    I32Const(i32),
    I64Const(i64),
    F32Const(f32),
    F64Const(f64),

    // Numeric Instructions
    // See <https://webassembly.github.io/spec/core/binary/instructions.html#numeric-instructions>
    I32Eqz,
    I32Eq,
    I32Ne,
    I32LtS,
    I32LtU,
    I32GtS,
    I32GtU,
    I32LeS,
    I32LeU,
    I32GeS,
    I32GeU,
    I64Eqz,
    I64Eq,
    I64Ne,
    I64LtS,
    I64LtU,
    I64GtS,
    I64GtU,
    I64LeS,
    I64LeU,
    I64GeS,
    I64GeU,
    F32Eq,
    F32Ne,
    F32Lt,
    F32Gt,
    F32Le,
    F32Ge,
    F64Eq,
    F64Ne,
    F64Lt,
    F64Gt,
    F64Le,
    F64Ge,
    I32Clz,
    I32Ctz,
    I32Popcnt,
    I32Add,
    I32Sub,
    I32Mul,
    I32DivS,
    I32DivU,
    I32RemS,
    I32RemU,
    I32And,
    I32Or,
    I32Xor,
    I32Shl,
    I32ShrS,
    I32ShrU,
    I32Rotl,
    I32Rotr,
    I64Clz,
    I64Ctz,
    I64Popcnt,
    I64Add,
    I64Sub,
    I64Mul,
    I64DivS,
    I64DivU,
    I64RemS,
    I64RemU,
    I64And,
    I64Or,
    I64Xor,
    I64Shl,
    I64ShrS,
    I64ShrU,
    I64Rotl,
    I64Rotr,
    F32Abs,
    F32Neg,
    F32Ceil,
    F32Floor,
    F32Trunc,
    F32Nearest,
    F32Sqrt,
    F32Add,
    F32Sub,
    F32Mul,
    F32Div,
    F32Min,
    F32Max,
    F32Copysign,
    F64Abs,
    F64Neg,
    F64Ceil,
    F64Floor,
    F64Trunc,
    F64Nearest,
    F64Sqrt,
    F64Add,
    F64Sub,
    F64Mul,
    F64Div,
    F64Min,
    F64Max,
    F64Copysign,
    I32WrapI64,
    I32TruncF32S,
    I32TruncF32U,
    I32TruncF64S,
    I32TruncF64U,
    I32Extend8S,
    I32Extend16S,
    I64Extend8S,
    I64Extend16S,
    I64Extend32S,
    I64ExtendI32S,
    I64ExtendI32U,
    I64TruncF32S,
    I64TruncF32U,
    I64TruncF64S,
    I64TruncF64U,
    F32ConvertI32S,
    F32ConvertI32U,
    F32ConvertI64S,
    F32ConvertI64U,
    F32DemoteF64,
    F64ConvertI32S,
    F64ConvertI32U,
    F64ConvertI64S,
    F64ConvertI64U,
    F64PromoteF32,
    I32ReinterpretF32,
    I64ReinterpretF64,
    F32ReinterpretI32,
    F64ReinterpretI64,
    I32TruncSatF32S,
    I32TruncSatF32U,
    I32TruncSatF64S,
    I32TruncSatF64U,
    I64TruncSatF32S,
    I64TruncSatF32U,
    I64TruncSatF64S,
    I64TruncSatF64U,
}