import type { BinaryOp, UnaryOp } from "../ast"
import type { Loc } from "./loc"

export type Operand = Loc | number

export type AbsInsnCopy = {
    type: "copy",
    dest: Loc,
    source: Operand,
}

export type AbsInsnGoto = {
    type: "goto",
    dest: string,
}

export type AbsInsnLabel = {
    type: "label",
    dest: string,
}

type UnaryInsn<Op> = {
    type: "unary",
    dest: Loc,
    op: Op,
    source: Operand,
}

// NOTE: We convert binary -> unary when going SSA3 -> SSA2
export type AbsInsn2Unary = UnaryInsn<UnaryOp | BinaryOp>

// Abstract instruction in two-address form
export type AbsInsn2 = AbsInsnCopy | AbsInsnLabel | AbsInsnGoto | AbsInsn2Unary

type CopyFn<A> = (dest: Loc, source: Operand) => A
type StringFn<A> = (name: string) => A
type UnaryFn<Op, A> = (dest: Loc, op: Op, source: Operand) => A
type UnaryFn2<A> = UnaryFn<UnaryOp | BinaryOp, A>

export const insnReduce2 = <A>(
    copy: CopyFn<A>,
    label: StringFn<A>,
    goto: StringFn<A>,
    unary: UnaryFn2<A>,
    insn: AbsInsn2
): A => {
    switch (insn.type) {
        case 'copy':
            return copy(insn.dest, insn.source)
        case 'label':
            return label(insn.dest)
        case 'goto':
            return goto(insn.dest)
        case 'unary':
            return unary(insn.dest, insn.op, insn.source)
    }
}

export type AbsInsn3Unary = UnaryInsn<UnaryOp>

export type AbsInsnBinary = {
    type: "binary",
    dest: Loc,
    source: Operand,
    op: BinaryOp,
    source1: Operand
}

// Abstract instruction in three-address form
export type AbsInsn3 = AbsInsnCopy | AbsInsnLabel | AbsInsnGoto | AbsInsn3Unary | AbsInsnBinary

export const CopyInsn = (dest: Loc, source: Operand): AbsInsnCopy => ({
    type: 'copy',
    dest,
    source,
})

export const UnaryInsn = <Op>(dest: Loc, op: Op, source: Operand): UnaryInsn<Op> => ({
    type: 'unary',
    dest,
    op,
    source,
})

export const BinaryInsn = (dest: Loc, source: Operand, op: BinaryOp, source1: Operand): AbsInsnBinary => ({
    type: 'binary',
    dest,
    source,
    op,
    source1,
})

export const LabelInsn = (dest: string): AbsInsnLabel => ({
    type: 'label',
    dest,
})

export const GotoInsn = (dest: string): AbsInsnGoto => ({
    type: 'goto',
    dest,
})