// TBD: Moving lib/parse here might make sense where the compiler has to evaluate WASM binaries on
// the fly, like when importing other WASM files through `import`. Module integration hasn't been
// specified, yet, though, and it somewhat conflicts with our dependency on Binaryen.

/** WebAssembly section ids. */
export enum SectionId {
  /** A custom section with an explicit name. */
  Custom = 0,
  /** Function types section. */
  Type = 1,
  /** Imports section. */
  Import = 2,
  /** Functions section. */
  Function = 3,
  /** Tables section. */
  Table = 4,
  /** Memories section. */
  Memory = 5,
  /** Globals section. */
  Global = 6,
  /** Exports section. */
  Export = 7,
  /** Start function section. */
  Start = 8,
  /** Table element section. */
  Element = 9,
  /** Function code section. */
  Code = 10,
  /** Memory segments section. */
  Data = 11
}

/** WebAssembly external kinds. */
export enum ExternalKind {
  /** External function. */
  Function = 0,
  /** External table. */
  Table = 1,
  /** External memory. */
  Memory = 2,
  /** External global. */
  Global = 3
}

/** WebAssembly name section kinds. */
export enum NameKind {
  /** Module name. */
  Module = 0,
  /** Function name. */
  Function = 1,
  /** Local name. */
  Local = 2,

  // see: https://github.com/WebAssembly/design/pull/1064

  /** Label name. */
  Label = 3,
  /** Function type name. */
  Type = 4,
  /** Table name. */
  Table = 5,
  /** Memory name. */
  Memory = 6,
  /** Global variable name. */
  Global = 7
}

/** WebAssembly types. */
export enum Type {
  i32 = 0x7f,
  i64 = 0x7e,
  f32 = 0x7d,
  f64 = 0x7c,
  anyfunc = 0x70,
  func = 0x60,
  none = 0x40
}

/** WebAssembly opcodes. */
export enum Op {
  unreachable = 0x00,
  nop = 0x01,
  block = 0x02,
  loop = 0x03,
  if_ = 0x04,
  else_ = 0x05,
  end = 0x0b,
  br = 0x0c,
  br_if = 0x0d,
  br_table = 0x0e,
  return_ = 0x0f,
  call = 0x10,
  call_indirect = 0x11,
  drop = 0x1a,
  select = 0x1b,
  get_local = 0x20,
  set_local = 0x21,
  tee_local = 0x22,
  get_global = 0x23,
  set_global = 0x24,
  i32_load = 0x28,
  i64_load = 0x29,
  f32_load = 0x2a,
  f64_load = 0x2b,
  i32_load8_s = 0x2c,
  i32_load8_u = 0x2d,
  i32_load16_s = 0x2e,
  i32_load16_u = 0x2f,
  i64_load8_s = 0x30,
  i64_load8_u = 0x31,
  i64_load16_s = 0x32,
  i64_load16_u = 0x33,
  i64_load32_s = 0x34,
  i64_load32_u = 0x35,
  i32_store = 0x36,
  i64_store = 0x37,
  f32_store = 0x38,
  f64_store = 0x39,
  i32_store8 = 0x3a,
  i32_store16 = 0x3b,
  i64_store8 = 0x3c,
  i64_store16 = 0x3d,
  i64_store32 = 0x3e,
  memory_size = 0x3f,
  memory_grow = 0x40,
  i32_const = 0x41,
  i64_const = 0x42,
  f32_const = 0x43,
  f64_const = 0x44,
  i32_eqz = 0x45,
  i32_eq = 0x46,
  i32_ne = 0x47,
  i32_lt_s = 0x48,
  i32_lt_u = 0x49,
  i32_gt_s = 0x4a,
  i32_gt_u = 0x4b,
  i32_le_s = 0x4c,
  i32_le_u = 0x4d,
  i32_ge_s = 0x4e,
  i32_ge_u = 0x4f,
  i64_eqz = 0x50,
  i64_eq = 0x51,
  i64_ne = 0x52,
  i64_lt_s = 0x53,
  i64_lt_u = 0x54,
  i64_gt_s = 0x55,
  i64_gt_u = 0x56,
  i64_le_s = 0x57,
  i64_le_u = 0x58,
  i64_ge_s = 0x59,
  i64_ge_u = 0x5a,
  f32_eq = 0x5b,
  f32_ne = 0x5c,
  f32_lt = 0x5d,
  f32_gt = 0x5e,
  f32_le = 0x5f,
  f32_ge = 0x60,
  f64_eq = 0x61,
  f64_ne = 0x62,
  f64_lt = 0x63,
  f64_gt = 0x64,
  f64_le = 0x65,
  f64_ge = 0x66,
  i32_clz = 0x67,
  i32_ctz = 0x68,
  i32_popcnt = 0x69,
  i32_add = 0x6a,
  i32_sub = 0x6b,
  i32_mul = 0x6c,
  i32_div_s = 0x6d,
  i32_div_u = 0x6e,
  i32_rem_s = 0x6f,
  i32_rem_u = 0x70,
  i32_and = 0x71,
  i32_or = 0x72,
  i32_xor = 0x73,
  i32_shl = 0x74,
  i32_shr_s = 0x75,
  i32_shr_u = 0x76,
  i32_rotl = 0x77,
  i32_rotr = 0x78,
  i64_clz = 0x79,
  i64_ctz = 0x7a,
  i64_popcnt = 0x7b,
  i64_add = 0x7c,
  i64_sub = 0x7d,
  i64_mul = 0x7e,
  i64_div_s = 0x7f,
  i64_div_u = 0x80,
  i64_rem_s = 0x81,
  i64_rem_u = 0x82,
  i64_and = 0x83,
  i64_or = 0x84,
  i64_xor = 0x85,
  i64_shl = 0x86,
  i64_shr_s = 0x87,
  i64_shr_u = 0x88,
  i64_rotl = 0x89,
  i64_rotr = 0x8a,
  f32_abs = 0x8b,
  f32_neg = 0x8c,
  f32_ceil = 0x8d,
  f32_floor = 0x8e,
  f32_trunc = 0x8f,
  f32_nearest = 0x90,
  f32_sqrt = 0x91,
  f32_add = 0x92,
  f32_sub = 0x93,
  f32_mul = 0x94,
  f32_div = 0x95,
  f32_min = 0x96,
  f32_max = 0x97,
  f32_copysign = 0x98,
  f64_abs = 0x99,
  f64_neg = 0x9a,
  f64_ceil = 0x9b,
  f64_floor = 0x9c,
  f64_trunc = 0x9d,
  f64_nearest = 0x9e,
  f64_sqrt = 0x9f,
  f64_add = 0xa0,
  f64_sub = 0xa1,
  f64_mul = 0xa2,
  f64_div = 0xa3,
  f64_min = 0xa4,
  f64_max = 0xa5,
  f64_copysign = 0xa6,
  i32_wrap_i64 = 0xa7,
  i32_trunc_s_f32 = 0xa8,
  i32_trunc_u_f32 = 0xa9,
  i32_trunc_s_f64 = 0xaa,
  i32_trunc_u_f64 = 0xab,
  i64_extend_s_i32 = 0xac,
  i64_extend_u_i32 = 0xad,
  i64_trunc_s_f32 = 0xae,
  i64_trunc_u_f32 = 0xaf,
  i64_trunc_s_f64 = 0xb0,
  i64_trunc_u_f64 = 0xb1,
  f32_convert_s_i32 = 0xb2,
  f32_convert_u_i32 = 0xb3,
  f32_convert_s_i64 = 0xb4,
  f32_convert_u_i64 = 0xb5,
  f32_demote_f64 = 0xb6,
  f64_convert_s_i32 = 0xb7,
  f64_convert_u_i32 = 0xb8,
  f64_convert_s_i64 = 0xb9,
  f64_convert_u_i64 = 0xba,
  f64_promote_f32 = 0xbb,
  i32_reinterpret_f32 = 0xbc,
  i64_reinterpret_f64 = 0xbd,
  f32_reinterpret_i32 = 0xbe,
  f64_reinterpret_i64 = 0xbf
}

enum ReaderState {
  HEADER
}

/** WebAssembly binary reader. */
export class Reader { // TODO

  /** Buffer being read. */
  private buffer: Uint8Array;
  /** Current read offset. */
  private offset: u32;
  /** Total length. */
  private length: u32;
  /** Current state. */
  private state: ReaderState;

  /** Constructs a new binary reader. */
  constructor(totalLength: u32, initialChunk: Uint8Array) {
    this.buffer = initialChunk;
    this.offset = 0;
    this.length = totalLength;
    this.state = ReaderState.HEADER;
  }

  /** Provides a chunk of data. */
  next(chunk: Uint8Array): void {
    if (!chunk.length) return;
    // var current = this.buffer;
    // var offset = this.offset;
    // var buffer = new Uint8Array((current.length - offset) + chunk.length);
    // buffer.set(current.subarray(offset), 0);
    // buffer.set(chunk, (current.length - offset));
    // this.buffer = buffer;
    // this.length -= this.offset;
    // this.offset = 0;
    unreachable();
  }

  finish(): void {
    unreachable();
  }
}