/* Executes WebAssembly spec-test commands (generated by gen.mjs) and prints
 * one line per command. The webassembly-spec-* corpus programs call it;
 * the differential harness runs them under Node and as compiled binaries
 * and compares the output, so V8 decides every expected value, trap and
 * error. Module bytes are inline base64 literals in each program's
 * data.mjs, which the build translates. */

/** The spec harness's `spectest` module (the reference interpreter's JS
 * harness), with its memory and table. */
function spectestImports(log) {
  return {
    print() {
      log("print");
    },
    print_i32(a) {
      log(`print_i32 ${a}`);
    },
    print_i64(a) {
      log(`print_i64 ${a}`);
    },
    print_f32(a) {
      log(`print_f32 ${show(a)}`);
    },
    print_f64(a) {
      log(`print_f64 ${show(a)}`);
    },
    print_i32_f32(a, b) {
      log(`print_i32_f32 ${a} ${show(b)}`);
    },
    print_f64_f64(a, b) {
      log(`print_f64_f64 ${show(a)} ${show(b)}`);
    },
    global_i32: 666,
    global_i64: 666n,
    global_f32: 666.6,
    global_f64: 666.6,
    table: new WebAssembly.Table({ initial: 10, maximum: 20, element: "anyfunc" }),
    memory: new WebAssembly.Memory({ initial: 1, maximum: 2 }),
  };
}

function show(v) {
  if (typeof v === "bigint") return `${v}n`;
  if (typeof v === "number") return Object.is(v, -0) ? "-0" : String(v);
  if (v === null) return "null";
  if (v === undefined) return "undefined";
  if (typeof v === "function") return "function";
  if (Array.isArray(v)) return `[${v.map(show).join(",")}]`;
  if (typeof v === "object" && typeof v.ref === "number") return `ref ${v.ref}`;
  return typeof v;
}

const refs = new Map();

function decode(arg) {
  const colon = arg.indexOf(":");
  const type = arg.slice(0, colon);
  const text = arg.slice(colon + 1);
  if (type === "i32") return Number(text) | 0;
  if (type === "i64") return BigInt.asIntN(64, BigInt(text));
  if (type === "f32") {
    const view = new DataView(new ArrayBuffer(4));
    view.setUint32(0, Number(text));
    return view.getFloat32(0);
  }
  if (type === "f64") {
    const view = new DataView(new ArrayBuffer(8));
    view.setBigUint64(0, BigInt(text));
    return view.getFloat64(0);
  }
  if (text === "null") return null;
  const n = Number(text);
  let ref = refs.get(n);
  if (ref === undefined) {
    ref = { ref: n };
    refs.set(n, ref);
  }
  return ref;
}

function failure(e) {
  return e instanceof Error ? `${e.name}: ${e.message}` : `threw ${show(e)}`;
}

export function run(modules, script) {
  const commands = JSON.parse(script);
  const lines = [];
  const log = (line) => {
    lines.push(line);
  };
  const imports = { spectest: spectestImports(log) };
  const named = new Map();
  let current = null;
  const instantiate = (index) =>
    new WebAssembly.Instance(new WebAssembly.Module(Buffer.from(modules[index], "base64")), imports);
  let file = "";
  for (const c of commands) {
    const op = c[0];
    if (op === "file") {
      file = c[1];
      log(`# ${file}`);
      continue;
    }
    if (op === "register") {
      const instance = c.length > 2 ? named.get(c[2]) : current;
      if (instance) imports[c[1]] = instance.exports;
      continue;
    }
    const at = `${file}:${c[1]}`;
    if (op === "module") {
      try {
        current = instantiate(c[2]);
        if (c.length > 3) named.set(c[3], current);
        log(`${at} module`);
      } catch (e) {
        current = null;
        log(`${at} module ${failure(e)}`);
      }
      continue;
    }
    if (op === "instantiate") {
      try {
        instantiate(c[2]);
        log(`${at} instantiated`);
      } catch (e) {
        log(`${at} ${e instanceof Error ? e.name : "threw"}`);
      }
      continue;
    }
    const instance = c[2] !== 0 ? named.get(c[2]) : current;
    if (!instance) {
      log(`${at} no instance`);
      continue;
    }
    try {
      const target = instance.exports[c[3]];
      if (op === "get") {
        log(`${at} ${show(target.value)}`);
        continue;
      }
      const args = c[4].map(decode);
      log(`${at} ${show(target(...args))}`);
    } catch (e) {
      log(`${at} ${failure(e)}`);
    }
  }
  console.log(lines.join("\n"));
}