import { parseGuildEmojiList } from './emojis';
import { parseGuildSoundList } from './sounds';
import { userStatuses, type Channel, type ChannelOverwrite, type UserStatus } from './types';
import type { GatewayUser } from './gateway';
import type { GuildEmoji } from './emojis';
import type { GuildSound } from './sounds';
import type { Message, MessageAttachment, MessageReaction } from './messages';

/**
 * Разбор payload'ов событий шлюза (AGENT.md §8.3).
 *
 * Все функции возвращают `null`, если кадр не соответствует контракту:
 * неизвестные и лишние поля не ломают диспетчер, а событие просто
 * игнорируется.
 */

export interface UserUpdateEvent {
  user: GatewayUser;
}

export interface GuildUpdateEvent {
  guild_id: string;
  name?: string;
  description?: string;
  /** Оформление сервера (AGENT.md 7.4): пустая строка означает «убрано». */
  icon_file_id?: string;
  banner_file_id?: string;
  splash_file_id?: string;
  accent_color?: number;
}

export interface GuildDeleteEvent {
  guild_id: string;
}

export interface GuildCreateEvent {
  guild_id: string;
}

export interface ChannelDeleteEvent {
  channel_id: string;
  guild_id: string;
}

export interface MemberUpdateEvent {
  guild_id: string;
  user_id: string;
  role_ids?: string[];
  role_id?: string;
  role_added?: boolean;
}

export interface MemberRemoveEvent {
  guild_id: string;
  user_id: string;
}

export interface RoleEvent {
  guild_id: string;
  role_id: string;
}

export interface GuildEmojisUpdateEvent {
  guild_id: string;
  emojis: GuildEmoji[];
}

export interface GuildSoundsUpdateEvent {
  guild_id: string;
  sounds: GuildSound[];
}

/** Событие `SOUNDBOARD_PLAY` (AGENT.md 7.13). */
export interface SoundboardPlayEvent {
  guild_id: string;
  channel_id: string;
  sound_id: string;
  file_id: string;
  name: string;
  user_id: string;
  played_at: string;
}

function asRecord(value: unknown): Record<string, unknown> | null {
  return typeof value === 'object' && value !== null ? (value as Record<string, unknown>) : null;
}

function asString(value: unknown): string | undefined {
  return typeof value === 'string' && value !== '' ? value : undefined;
}

function asStringArray(value: unknown): string[] | undefined {
  return Array.isArray(value)
    ? value.filter((item): item is string => typeof item === 'string')
    : undefined;
}

/** Пользователь в объёме `USER_UPDATE` (совместим со снапшотом READY). */
export function parseGatewayUserPayload(value: unknown): GatewayUser | null {
  const record = asRecord(value);
  if (record === null) {
    return null;
  }
  const id = asString(record['id']);
  const username = asString(record['username']);
  if (id === undefined || username === undefined) {
    return null;
  }
  const user: GatewayUser = {
    id,
    username,
    display_name: asString(record['display_name']) ?? username,
    is_instance_admin: record['is_instance_admin'] === true,
    badges: asStringArray(record['badges']) ?? [],
  };
  const avatar = asString(record['avatar_file_id']);
  const status = asString(record['status']);
  const customStatus = asString(record['custom_status']);
  const customEmoji = asString(record['custom_status_emoji']);
  if (avatar !== undefined) {
    user.avatar_file_id = avatar;
  }
  if (userStatuses.includes(status as UserStatus)) {
    user.status = status as UserStatus;
  }
  if (customStatus !== undefined) {
    user.custom_status = customStatus;
  }
  if (customEmoji !== undefined) {
    user.custom_status_emoji = customEmoji;
  }
  return user;
}

/** Деструктурирует `d` у событий, где payload вложен в `user`. */
export function parseUserUpdate(value: unknown): UserUpdateEvent | null {
  const record = asRecord(value);
  if (record === null) {
    return null;
  }
  const user = parseGatewayUserPayload(record['user'] ?? value);
  return user === null ? null : { user };
}

export function parseGuildUpdate(value: unknown): GuildUpdateEvent | null {
  const record = asRecord(value);
  const guildId = asString(record?.['guild_id']);
  if (record === null || guildId === undefined) {
    return null;
  }
  const event: GuildUpdateEvent = { guild_id: guildId };
  const name = asString(record['name']);
  const description = asString(record['description']);
  if (name !== undefined) {
    event.name = name;
  }
  if (description !== undefined) {
    event.description = description;
  }
  // Оформление: сервер присылает null, когда файл удалён, — приводим к пустой
  // строке, чтобы заглушка-буквы вернулась сразу (AGENT.md 11.6).
  for (const field of ['icon_file_id', 'banner_file_id', 'splash_file_id'] as const) {
    if (field in record) {
      event[field] = asString(record[field]) ?? '';
    }
  }
  if (typeof record['accent_color'] === 'number') {
    event.accent_color = record['accent_color'];
  }
  return event;
}

export function parseGuildId(value: unknown): string | null {
  const record = asRecord(value);
  return asString(record?.['guild_id']) ?? null;
}

export function parseChannelDelete(value: unknown): ChannelDeleteEvent | null {
  const record = asRecord(value);
  const channelId = asString(record?.['channel_id']);
  const guildId = asString(record?.['guild_id']);
  if (channelId === undefined || guildId === undefined) {
    return null;
  }
  return { channel_id: channelId, guild_id: guildId };
}

export function parseMemberUpdate(value: unknown): MemberUpdateEvent | null {
  const record = asRecord(value);
  const guildId = asString(record?.['guild_id']);
  const userId = asString(record?.['user_id']);
  if (record === null || guildId === undefined || userId === undefined) {
    return null;
  }
  const event: MemberUpdateEvent = { guild_id: guildId, user_id: userId };
  const roleIds = asStringArray(record['role_ids']);
  const roleId = asString(record['role_id']);
  if (roleIds !== undefined) {
    event.role_ids = roleIds;
  }
  if (roleId !== undefined) {
    event.role_id = roleId;
  }
  if (typeof record['role_added'] === 'boolean') {
    event.role_added = record['role_added'];
  }
  return event;
}

export function parseMemberRemove(value: unknown): MemberRemoveEvent | null {
  const event = parseMemberUpdate(value);
  return event === null ? null : { guild_id: event.guild_id, user_id: event.user_id };
}

export function parseRoleEvent(value: unknown): RoleEvent | null {
  const record = asRecord(value);
  const guildId = asString(record?.['guild_id']);
  // Сервер шлёт тело роли (поле id), старый формат — ссылку role_id:
  // принимаем оба, иначе событие роли отбрасывалось и список не обновлялся.
  const roleId = asString(record?.['role_id']) ?? asString(record?.['id']);
  if (record === null || guildId === undefined || roleId === undefined) {
    return null;
  }
  return { guild_id: guildId, role_id: roleId };
}

/**
 * `GUILD_EMOJIS_UPDATE`: набор эмодзи сервера изменился (загрузка,
 * переименование, удаление). Список приходит целиком — тем же форматом, что
 * и в снапшоте READY, поэтому заменяем его в сторе, а не мержим.
 */
export function parseGuildEmojisUpdate(value: unknown): GuildEmojisUpdateEvent | null {
  const record = asRecord(value);
  const guildId = asString(record?.['guild_id']);
  if (record === null || guildId === undefined) {
    return null;
  }
  return { guild_id: guildId, emojis: parseGuildEmojiList(record['emojis']) };
}

/**
 * `GUILD_SOUNDS_UPDATE`: набор звуков сервера изменился (AGENT.md 7.13).
 * Список приходит целиком — тем же форматом, что в снапшоте READY.
 */
export function parseGuildSoundsUpdate(value: unknown): GuildSoundsUpdateEvent | null {
  const record = asRecord(value);
  const guildId = asString(record?.['guild_id']);
  if (record === null || guildId === undefined) {
    return null;
  }
  return { guild_id: guildId, sounds: parseGuildSoundList(record['sounds']) };
}

/**
 * `SOUNDBOARD_PLAY`: кто-то сыграл звук в голосовой комнате. Событие
 * приходит только участникам этой комнаты, и каждый клиент играет звук сам.
 */
export function parseSoundboardPlay(value: unknown): SoundboardPlayEvent | null {
  const record = asRecord(value);
  if (record === null) {
    return null;
  }
  const guildId = asString(record['guild_id']);
  const channelId = asString(record['channel_id']);
  const soundId = asString(record['sound_id']);
  const fileId = asString(record['file_id']);
  const userId = asString(record['user_id']);
  if (
    guildId === undefined ||
    channelId === undefined ||
    soundId === undefined ||
    fileId === undefined ||
    userId === undefined
  ) {
    return null;
  }
  return {
    guild_id: guildId,
    channel_id: channelId,
    sound_id: soundId,
    file_id: fileId,
    name: asString(record['name']) ?? '',
    user_id: userId,
    played_at: asString(record['played_at']) ?? '',
  };
}

/** Канал из `CHANNEL_CREATE`/`CHANNEL_UPDATE` — та же форма, что в REST. */
/** `GUILD_CHANNELS_SYNC`: права комнат сервера изменились — перечитать список. */
export function parseGuildChannelsSyncEvent(value: unknown): { guild_id: string } | null {
  const record = asRecord(value);
  if (record === null) {
    return null;
  }
  const guildId = asString(record['guild_id']);
  return guildId === undefined ? null : { guild_id: guildId };
}

/** parseChannelOverwrites читает список оверрайдов прав комнаты. */
export function parseChannelOverwrites(value: unknown): ChannelOverwrite[] {
  if (!Array.isArray(value)) {
    return [];
  }
  const result: ChannelOverwrite[] = [];
  for (const item of value) {
    const record = asRecord(item);
    if (record === null) {
      continue;
    }
    const targetType = asString(record['target_type']);
    const targetId = asString(record['target_id']);
    if ((targetType !== 'role' && targetType !== 'user') || targetId === undefined) {
      continue;
    }
    result.push({
      target_type: targetType,
      target_id: targetId,
      allow: asString(record['allow']) ?? '0',
      deny: asString(record['deny']) ?? '0',
    });
  }
  return result;
}

export function parseChannelPayload(value: unknown): Channel | null {
  const record = asRecord(value);
  if (record === null) {
    return null;
  }
  const id = asString(record['id']);
  const name = asString(record['name']);
  const type = asString(record['type']);
  if (id === undefined || name === undefined) {
    return null;
  }
  if (type !== 'text' && type !== 'voice' && type !== 'category' && type !== 'dm') {
    return null;
  }
  const channel: Channel = {
    id,
    name,
    type,
    position: typeof record['position'] === 'number' ? record['position'] : 0,
  };
  const guildId = asString(record['guild_id']);
  const parentId = asString(record['parent_id']);
  if (guildId !== undefined) {
    channel.guild_id = guildId;
  }
  if (parentId !== undefined) {
    channel.parent_id = parentId;
  }
  if (typeof record['user_limit'] === 'number') {
    channel.user_limit = record['user_limit'];
  }
  if (typeof record['slowmode_seconds'] === 'number') {
    channel.slowmode_seconds = record['slowmode_seconds'];
  }
  if (typeof record['can_send'] === 'boolean') {
    channel.can_send = record['can_send'];
  }
  if (typeof record['can_connect'] === 'boolean') {
    channel.can_connect = record['can_connect'];
  }
  if (typeof record['can_view'] === 'boolean') {
    channel.can_view = record['can_view'];
  }
  // Права комнаты: нужны редактору доступа (AGENT.md 6.2).
  const overwrites = parseChannelOverwrites(record['permission_overwrites']);
  if (overwrites.length > 0) {
    channel.permission_overwrites = overwrites;
  }
  // Фон комнаты: приходит в READY и CHANNEL_UPDATE (AGENT.md 7.5).
  const backgroundFileId = asString(record['background_file_id']);
  if (backgroundFileId !== undefined) {
    channel.background_file_id = backgroundFileId;
  }
  // Личная беседа: собеседник и последнее сообщение (READY и CHANNEL_*).
  const recipientId = asString(record['recipient_id']);
  const iconFileId = asString(record['icon_file_id']);
  const status = asString(record['status']);
  const lastMessageId = asString(record['last_message_id']);
  const lastMessageAt = asString(record['last_message_at']);
  if (recipientId !== undefined) {
    channel.recipient_id = recipientId;
  }
  if (iconFileId !== undefined) {
    channel.icon_file_id = iconFileId;
  }
  if (userStatuses.includes(status as UserStatus)) {
    channel.status = status as UserStatus;
  }
  if (lastMessageId !== undefined) {
    channel.last_message_id = lastMessageId;
  }
  if (lastMessageAt !== undefined) {
    channel.last_message_at = lastMessageAt;
  }
  return channel;
}

/* ------------------------------------------------------------------ */
/* Друзья и личные беседы (AGENT.md §8.3 / 7.8)                        */
/* ------------------------------------------------------------------ */

export interface DmChannelEvent {
  channel_id: string;
}

export interface RelationshipEvent {
  user_id: string;
}

export interface PresenceEvent {
  user_id: string;
  status?: UserStatus;
  visible_status?: UserStatus;
  custom_status?: string;
  last_seen_at?: string;
}

/** `DM_CHANNEL_CREATE`: создана личная беседа — перечитываем список бесед. */
export function parseDmChannelEvent(value: unknown): DmChannelEvent | null {
  const record = asRecord(value);
  const channelId = asString(record?.['channel_id']);
  return record === null || channelId === undefined ? null : { channel_id: channelId };
}

/** `RELATIONSHIP_UPDATE`: изменилась связь с пользователем. */
export function parseRelationshipEvent(value: unknown): RelationshipEvent | null {
  const record = asRecord(value);
  const userId = asString(record?.['user_id']);
  return record === null || userId === undefined ? null : { user_id: userId };
}

/**
 * `PRESENCE_UPDATE`: статус друга. Поля необязательны — сервер присылает
 * только изменившиеся, поэтому разбираем каждое отдельно.
 */
export function parsePresenceEvent(value: unknown): PresenceEvent | null {
  const record = asRecord(value);
  const userId = asString(record?.['user_id']);
  if (record === null || userId === undefined) {
    return null;
  }
  const event: PresenceEvent = { user_id: userId };
  const status = asString(record['status']);
  const visibleStatus = asString(record['visible_status']);
  const customStatus = asString(record['custom_status']);
  const lastSeenAt = asString(record['last_seen_at']);
  if (userStatuses.includes(status as UserStatus)) {
    event.status = status as UserStatus;
  }
  if (userStatuses.includes(visibleStatus as UserStatus)) {
    event.visible_status = visibleStatus as UserStatus;
  }
  if (customStatus !== undefined) {
    event.custom_status = customStatus;
  }
  if (lastSeenAt !== undefined) {
    event.last_seen_at = lastSeenAt;
  }
  return event;
}

/* ------------------------------------------------------------------ */
/* События сообщений Фазы 2 (AGENT.md §8.3)                            */
/* ------------------------------------------------------------------ */

export interface MessageDeleteEvent {
  id: string;
  channel_id: string;
}

export interface ReactionEvent {
  channel_id: string;
  message_id: string;
  user_id: string;
  emoji: string;
}

export interface PinsUpdateEvent {
  channel_id: string;
  message_id: string;
  pinned: boolean;
}

export interface TypingStartEvent {
  channel_id: string;
  user_id: string;
}

export interface ReadStateEvent {
  channel_id: string;
  last_message_id?: string;
  mention_count: number;
}

function asNumber(value: unknown): number | undefined {
  return typeof value === 'number' && Number.isFinite(value) ? value : undefined;
}

function parseAttachment(value: unknown): MessageAttachment | null {
  const record = asRecord(value);
  const fileId = asString(record?.['file_id']);
  const filename = asString(record?.['filename']);
  if (record === null || fileId === undefined || filename === undefined) {
    return null;
  }
  const attachment: MessageAttachment = { file_id: fileId, filename };
  const contentType = asString(record['content_type']);
  const sizeBytes = asNumber(record['size_bytes']);
  const width = asNumber(record['width']);
  const height = asNumber(record['height']);
  if (contentType !== undefined) {
    attachment.content_type = contentType;
  }
  if (sizeBytes !== undefined) {
    attachment.size_bytes = sizeBytes;
  }
  if (width !== undefined) {
    attachment.width = width;
  }
  if (height !== undefined) {
    attachment.height = height;
  }
  return attachment;
}

function parseReaction(value: unknown): MessageReaction | null {
  const record = asRecord(value);
  const emoji = asString(record?.['emoji']);
  if (record === null || emoji === undefined) {
    return null;
  }
  const reaction: MessageReaction = {
    emoji,
    count: asNumber(record['count']) ?? 0,
    me: record['me'] === true,
  };
  const userIds = asStringArray(record['user_ids']);
  if (userIds !== undefined) {
    reaction.user_ids = userIds;
  }
  return reaction;
}

/** Сообщение — та же форма, что в REST (payload `MESSAGE_CREATE`/`MESSAGE_UPDATE`). */
export function parseMessagePayload(value: unknown): Message | null {
  const record = asRecord(value);
  if (record === null) {
    return null;
  }
  const id = asString(record['id']);
  const channelId = asString(record['channel_id']);
  const createdAt = asString(record['created_at']);
  if (id === undefined || channelId === undefined || createdAt === undefined) {
    return null;
  }
  const message: Message = {
    id,
    channel_id: channelId,
    content: typeof record['content'] === 'string' ? record['content'] : '',
    type: asString(record['type']) ?? 'default',
    pinned: record['pinned'] === true,
    attachments: Array.isArray(record['attachments'])
      ? record['attachments']
          .map(parseAttachment)
          .filter((item): item is MessageAttachment => item !== null)
      : [],
    mentions: asStringArray(record['mentions']) ?? [],
    reactions: Array.isArray(record['reactions'])
      ? record['reactions']
          .map(parseReaction)
          .filter((item): item is MessageReaction => item !== null)
      : [],
    created_at: createdAt,
  };
  const authorId = asString(record['author_id']);
  const replyToId = asString(record['reply_to_id']);
  const editedAt = asString(record['edited_at']);
  if (authorId !== undefined) {
    message.author_id = authorId;
  }
  if (replyToId !== undefined) {
    message.reply_to_id = replyToId;
  }
  if (editedAt !== undefined) {
    message.edited_at = editedAt;
  }
  return message;
}

export function parseMessageDelete(value: unknown): MessageDeleteEvent | null {
  const record = asRecord(value);
  const id = asString(record?.['id']);
  const channelId = asString(record?.['channel_id']);
  if (record === null || id === undefined || channelId === undefined) {
    return null;
  }
  return { id, channel_id: channelId };
}

export function parseReactionEvent(value: unknown): ReactionEvent | null {
  const record = asRecord(value);
  const channelId = asString(record?.['channel_id']);
  const messageId = asString(record?.['message_id']);
  const userId = asString(record?.['user_id']);
  const emoji = asString(record?.['emoji']);
  if (
    record === null ||
    channelId === undefined ||
    messageId === undefined ||
    userId === undefined ||
    emoji === undefined
  ) {
    return null;
  }
  return { channel_id: channelId, message_id: messageId, user_id: userId, emoji };
}

export function parsePinsUpdate(value: unknown): PinsUpdateEvent | null {
  const record = asRecord(value);
  const channelId = asString(record?.['channel_id']);
  const messageId = asString(record?.['message_id']);
  if (record === null || channelId === undefined || messageId === undefined) {
    return null;
  }
  return { channel_id: channelId, message_id: messageId, pinned: record['pinned'] === true };
}

export function parseTypingStart(value: unknown): TypingStartEvent | null {
  const record = asRecord(value);
  const channelId = asString(record?.['channel_id']);
  const userId = asString(record?.['user_id']);
  if (record === null || channelId === undefined || userId === undefined) {
    return null;
  }
  return { channel_id: channelId, user_id: userId };
}

export function parseReadStateUpdate(value: unknown): ReadStateEvent | null {
  const record = asRecord(value);
  const channelId = asString(record?.['channel_id']);
  if (record === null || channelId === undefined) {
    return null;
  }
  const event: ReadStateEvent = {
    channel_id: channelId,
    mention_count: asNumber(record['mention_count']) ?? 0,
  };
  const lastMessageId = asString(record['last_message_id']);
  if (lastMessageId !== undefined) {
    event.last_message_id = lastMessageId;
  }
  return event;
}