import { Client } from "@buape/carbon";
import { GatewayIntents, GatewayPlugin } from "@buape/carbon/gateway";
import { Routes } from "discord-api-types/v10";
import { resolveTextChunkLimit } from "../../auto-reply/chunk.js";
import { listNativeCommandSpecsForConfig } from "../../auto-reply/commands-registry.js";
import { listSkillCommandsForAgents } from "../../auto-reply/skill-commands.js";
import type { HistoryEntry } from "../../auto-reply/reply/history.js";
import {
  isNativeCommandsExplicitlyDisabled,
  resolveNativeCommandsEnabled,
  resolveNativeSkillsEnabled,
} from "../../config/commands.js";
import type { ClawdbotConfig, ReplyToMode } from "../../config/config.js";
import { loadConfig } from "../../config/config.js";
import { danger, logVerbose, shouldLogVerbose } from "../../globals.js";
import { createSubsystemLogger } from "../../logging.js";
import type { RuntimeEnv } from "../../runtime.js";
import { resolveDiscordAccount } from "../accounts.js";
import { attachDiscordGatewayLogging } from "../gateway-logging.js";
import { getDiscordGatewayEmitter, waitForDiscordGatewayStop } from "../monitor.gateway.js";
import { fetchDiscordApplicationId } from "../probe.js";
import { normalizeDiscordToken } from "../token.js";
import {
  DiscordMessageListener,
  DiscordReactionListener,
  DiscordReactionRemoveListener,
  registerDiscordListener,
} from "./listeners.js";
import { createDiscordMessageHandler } from "./message-handler.js";
import {
  createDiscordCommandArgFallbackButton,
  createDiscordNativeCommand,
} from "./native-command.js";

export type MonitorDiscordOpts = {
  token?: string;
  accountId?: string;
  config?: ClawdbotConfig;
  runtime?: RuntimeEnv;
  abortSignal?: AbortSignal;
  mediaMaxMb?: number;
  historyLimit?: number;
  replyToMode?: ReplyToMode;
};

function summarizeAllowList(list?: Array<string | number>) {
  if (!list || list.length === 0) return "any";
  const sample = list.slice(0, 4).map((entry) => String(entry));
  const suffix = list.length > sample.length ? ` (+${list.length - sample.length})` : "";
  return `${sample.join(", ")}${suffix}`;
}

function summarizeGuilds(entries?: Record<string, unknown>) {
  if (!entries || Object.keys(entries).length === 0) return "any";
  const keys = Object.keys(entries);
  const sample = keys.slice(0, 4);
  const suffix = keys.length > sample.length ? ` (+${keys.length - sample.length})` : "";
  return `${sample.join(", ")}${suffix}`;
}

export async function monitorDiscordProvider(opts: MonitorDiscordOpts = {}) {
  const cfg = opts.config ?? loadConfig();
  const account = resolveDiscordAccount({
    cfg,
    accountId: opts.accountId,
  });
  const token = normalizeDiscordToken(opts.token ?? undefined) ?? account.token;
  if (!token) {
    throw new Error(
      `Discord bot token missing for account "${account.accountId}" (set discord.accounts.${account.accountId}.token or DISCORD_BOT_TOKEN for default).`,
    );
  }

  const runtime: RuntimeEnv = opts.runtime ?? {
    log: console.log,
    error: console.error,
    exit: (code: number): never => {
      throw new Error(`exit ${code}`);
    },
  };

  const discordCfg = account.config;
  const dmConfig = discordCfg.dm;
  const guildEntries = discordCfg.guilds;
  const groupPolicy = discordCfg.groupPolicy ?? "open";
  const allowFrom = dmConfig?.allowFrom;
  const mediaMaxBytes = (opts.mediaMaxMb ?? discordCfg.mediaMaxMb ?? 8) * 1024 * 1024;
  const textLimit = resolveTextChunkLimit(cfg, "discord", account.accountId, {
    fallbackLimit: 2000,
  });
  const historyLimit = Math.max(
    0,
    opts.historyLimit ?? discordCfg.historyLimit ?? cfg.messages?.groupChat?.historyLimit ?? 20,
  );
  const replyToMode = opts.replyToMode ?? discordCfg.replyToMode ?? "off";
  const dmEnabled = dmConfig?.enabled ?? true;
  const dmPolicy = dmConfig?.policy ?? "pairing";
  const groupDmEnabled = dmConfig?.groupEnabled ?? false;
  const groupDmChannels = dmConfig?.groupChannels;
  const nativeEnabled = resolveNativeCommandsEnabled({
    providerId: "discord",
    providerSetting: discordCfg.commands?.native,
    globalSetting: cfg.commands?.native,
  });
  const nativeSkillsEnabled = resolveNativeSkillsEnabled({
    providerId: "discord",
    providerSetting: discordCfg.commands?.nativeSkills,
    globalSetting: cfg.commands?.nativeSkills,
  });
  const nativeDisabledExplicit = isNativeCommandsExplicitlyDisabled({
    providerSetting: discordCfg.commands?.native,
    globalSetting: cfg.commands?.native,
  });
  const useAccessGroups = cfg.commands?.useAccessGroups !== false;
  const sessionPrefix = "discord:slash";
  const ephemeralDefault = true;

  if (shouldLogVerbose()) {
    logVerbose(
      `discord: config dm=${dmEnabled ? "on" : "off"} dmPolicy=${dmPolicy} allowFrom=${summarizeAllowList(allowFrom)} groupDm=${groupDmEnabled ? "on" : "off"} groupDmChannels=${summarizeAllowList(groupDmChannels)} groupPolicy=${groupPolicy} guilds=${summarizeGuilds(guildEntries)} historyLimit=${historyLimit} mediaMaxMb=${Math.round(mediaMaxBytes / (1024 * 1024))} native=${nativeEnabled ? "on" : "off"} nativeSkills=${nativeSkillsEnabled ? "on" : "off"} accessGroups=${useAccessGroups ? "on" : "off"}`,
    );
  }

  const applicationId = await fetchDiscordApplicationId(token, 4000);
  if (!applicationId) {
    throw new Error("Failed to resolve Discord application id");
  }

  const skillCommands =
    nativeEnabled && nativeSkillsEnabled ? listSkillCommandsForAgents({ cfg }) : [];
  const commandSpecs = nativeEnabled ? listNativeCommandSpecsForConfig(cfg, { skillCommands }) : [];
  const commands = commandSpecs.map((spec) =>
    createDiscordNativeCommand({
      command: spec,
      cfg,
      discordConfig: discordCfg,
      accountId: account.accountId,
      sessionPrefix,
      ephemeralDefault,
    }),
  );

  const client = new Client(
    {
      baseUrl: "http://localhost",
      deploySecret: "a",
      clientId: applicationId,
      publicKey: "a",
      token,
      autoDeploy: nativeEnabled,
    },
    {
      commands,
      listeners: [],
      components: [
        createDiscordCommandArgFallbackButton({
          cfg,
          discordConfig: discordCfg,
          accountId: account.accountId,
          sessionPrefix,
        }),
      ],
    },
    [
      new GatewayPlugin({
        reconnect: {
          maxAttempts: Number.POSITIVE_INFINITY,
        },
        intents:
          GatewayIntents.Guilds |
          GatewayIntents.GuildMessages |
          GatewayIntents.MessageContent |
          GatewayIntents.DirectMessages |
          GatewayIntents.GuildMessageReactions |
          GatewayIntents.DirectMessageReactions,
        autoInteractions: true,
      }),
    ],
  );

  const logger = createSubsystemLogger("discord/monitor");
  const guildHistories = new Map<string, HistoryEntry[]>();
  let botUserId: string | undefined;

  if (nativeDisabledExplicit) {
    await clearDiscordNativeCommands({
      client,
      applicationId,
      runtime,
    });
  }

  try {
    const botUser = await client.fetchUser("@me");
    botUserId = botUser?.id;
  } catch (err) {
    runtime.error?.(danger(`discord: failed to fetch bot identity: ${String(err)}`));
  }

  const messageHandler = createDiscordMessageHandler({
    cfg,
    discordConfig: discordCfg,
    accountId: account.accountId,
    token,
    runtime,
    botUserId,
    guildHistories,
    historyLimit,
    mediaMaxBytes,
    textLimit,
    replyToMode,
    dmEnabled,
    groupDmEnabled,
    groupDmChannels,
    allowFrom,
    guildEntries,
  });

  registerDiscordListener(client.listeners, new DiscordMessageListener(messageHandler, logger));
  registerDiscordListener(
    client.listeners,
    new DiscordReactionListener({
      cfg,
      accountId: account.accountId,
      runtime,
      botUserId,
      guildEntries,
      logger,
    }),
  );
  registerDiscordListener(
    client.listeners,
    new DiscordReactionRemoveListener({
      cfg,
      accountId: account.accountId,
      runtime,
      botUserId,
      guildEntries,
      logger,
    }),
  );

  runtime.log?.(`logged in to discord${botUserId ? ` as ${botUserId}` : ""}`);

  const gateway = client.getPlugin<GatewayPlugin>("gateway");
  const gatewayEmitter = getDiscordGatewayEmitter(gateway);
  const stopGatewayLogging = attachDiscordGatewayLogging({
    emitter: gatewayEmitter,
    runtime,
  });
  // Timeout to detect zombie connections where HELLO is never received.
  const HELLO_TIMEOUT_MS = 30000;
  let helloTimeoutId: ReturnType<typeof setTimeout> | undefined;
  const onGatewayDebug = (msg: unknown) => {
    const message = String(msg);
    if (!message.includes("WebSocket connection opened")) return;
    if (helloTimeoutId) clearTimeout(helloTimeoutId);
    helloTimeoutId = setTimeout(() => {
      if (!gateway?.isConnected) {
        runtime.log?.(
          danger(
            `connection stalled: no HELLO received within ${HELLO_TIMEOUT_MS}ms, forcing reconnect`,
          ),
        );
        gateway?.disconnect();
        gateway?.connect(false);
      }
      helloTimeoutId = undefined;
    }, HELLO_TIMEOUT_MS);
  };
  gatewayEmitter?.on("debug", onGatewayDebug);
  try {
    await waitForDiscordGatewayStop({
      gateway: gateway
        ? {
            emitter: gatewayEmitter,
            disconnect: () => gateway.disconnect(),
          }
        : undefined,
      abortSignal: opts.abortSignal,
      onGatewayError: (err) => {
        runtime.error?.(danger(`discord gateway error: ${String(err)}`));
      },
      shouldStopOnError: (err) => {
        const message = String(err);
        return (
          message.includes("Max reconnect attempts") || message.includes("Fatal Gateway error")
        );
      },
    });
  } finally {
    stopGatewayLogging();
    if (helloTimeoutId) clearTimeout(helloTimeoutId);
    gatewayEmitter?.removeListener("debug", onGatewayDebug);
  }
}

async function clearDiscordNativeCommands(params: {
  client: Client;
  applicationId: string;
  runtime: RuntimeEnv;
}) {
  try {
    await params.client.rest.put(Routes.applicationCommands(params.applicationId), {
      body: [],
    });
    logVerbose("discord: cleared native commands (commands.native=false)");
  } catch (err) {
    params.runtime.error?.(danger(`discord: failed to clear native commands: ${String(err)}`));
  }
}