import { BinaryType, Stmt } from "../ast.ts";
import { VType, vtypeToString } from "../vtype.ts";

export type Mir = {
    fns: Fn[];
};

export type Fn = {
    stmt: Stmt;
    locals: Local[];
    blocks: Block[];
};

export type LocalId = number;

export type Local = {
    id: LocalId;
    vtype: VType;
};

export type BlockId = number;

export type Block = {
    id: BlockId;
    ops: Op[];
    ter: Ter;
    label?: string;
};

export type Op = {
    kind: OpKind;
};

type L = LocalId;

export type OpKind =
    | { type: "error" }
    | { type: "return" }
    | { type: "drop"; val: L }
    | { type: "assign"; dst: L; src: L }
    | { type: "assign_error"; dst: L }
    | { type: "assign_null"; dst: L }
    | { type: "assign_bool"; dst: L; val: boolean }
    | { type: "assign_int"; dst: L; val: number }
    | { type: "assign_string"; dst: L; val: string }
    | { type: "assign_fn"; dst: L; stmt: Stmt }
    | { type: "field"; dst: L; subject: L; ident: string }
    | { type: "assign_field"; subject: L; ident: string; src: L }
    | { type: "index"; dst: L; subject: L; index: number }
    | { type: "assign_field"; subject: L; index: L; src: L }
    | { type: "call_val"; dst: L; subject: L; args: L[] }
    | { type: "binary"; binaryType: BinaryType; dst: L; left: L; right: L };

export type Ter = {
    kind: TerKind;
};

export type TerKind =
    | { type: "error" }
    | { type: "jump"; target: BlockId }
    | { type: "if"; cond: L; truthy: BlockId; falsy: BlockId };

export function printMir(mir: Mir) {
    for (const fn of mir.fns) {
        const stmt = fn.stmt;
        if (stmt.kind.type !== "fn") {
            throw new Error();
        }
        const name = stmt.kind.ident;

        const vtype = stmt.kind.vtype;
        if (vtype?.type !== "fn") {
            throw new Error();
        }
        const generics = vtype.genericParams
            ?.map(({ ident }) => `${ident}`).join(", ") ?? "";
        const params = vtype.params
            .map(({ vtype }, i) =>
                `_${fn.locals[i + 1].id}: ${vtypeToString(vtype)}`
            )
            .join(", ");
        const returnType = vtypeToString(vtype.returnType);
        console.log(`${name}${generics}(${params}) -> ${returnType}:`);
        for (const { id, vtype } of fn.locals) {
            console.log(`    let _${id}: ${vtypeToString(vtype)};`);
        }
        for (const block of fn.blocks) {
            console.log(`.${block.label ?? block.id}:`);
            for (const op of block.ops) {
                const k = op.kind;
                switch (k.type) {
                    case "error":
                        console.log(`    <error>;`);
                        break;
                    case "return":
                        console.log(`    return;`);
                        break;
                    case "drop":
                        console.log(`    drop _${k.val};`);
                        break;
                    case "assign":
                        console.log(`    _${k.dst} = _${k.src};`);
                        break;
                    case "assign_error":
                        console.log(`    _${k.dst} = <error>;`);
                        break;
                    case "assign_null":
                        console.log(`    _${k.dst} = null;`);
                        break;
                    case "assign_bool":
                        console.log(`    _${k.dst} = ${k.val};`);
                        break;
                    case "assign_int":
                        console.log(`    _${k.dst} = ${k.val};`);
                        break;
                    case "assign_string":
                        console.log(`    _${k.dst} = "${k.val}";`);
                        break;
                    case "assign_fn": {
                        const stmt = k.stmt;
                        if (stmt.kind.type !== "fn") {
                            throw new Error();
                        }
                        console.log(`    _${k.dst} = ${stmt.kind.ident};`);
                        break;
                    }
                    case "field":
                        console.log(
                            `    _${k.dst} = _${k.subject}.${k.ident};`,
                        );
                        break;
                    case "index":
                        console.log(
                            `    _${k.dst} = _${k.subject}[_${k.index}];`,
                        );
                        break;
                    case "call_val": {
                        const args = k.args.map((arg) => `_${arg}`).join(", ");
                        console.log(`    _${k.dst} = _${k.subject}(${args});`);
                        break;
                    }
                    case "binary": {
                        console.log(
                            `    _${k.dst} = _${k.left} ${k.binaryType} _${k.right};`,
                        );
                        break;
                    }
                }
            }
        }
    }
}