import {
  Client,
  GatewayIntentBits,
  REST,
  Routes,
  SlashCommandBuilder,
  type ChatInputCommandInteraction,
  type Message,
  type TextChannel,
} from "discord.js";
import { logger } from "./logger.js";

export interface Prompt {
  text: string;
  channelId: string;
  userId: string;
  guildId: string | null;
}

export function shouldIgnoreMessage(message: { author: { bot: boolean } }): boolean {
  return message.author.bot;
}

export function extractPromptFromMention(content: string, botId: string): string {
  // Remove user mentions (<@ID> or <@!ID>) and role mentions (<@&ID>) for the bot
  return content
    .replace(/<@[!&]?\d+>/g, "")
    .trim();
}

export class DiscordBot {
  private client: Client;
  private promptHandler: ((prompt: Prompt) => void) | null = null;
  private resetHandler: ((channelId: string) => void) | null = null;

  constructor() {
    this.client = new Client({
      intents: [
        GatewayIntentBits.Guilds,
        GatewayIntentBits.GuildMessages,
        GatewayIntentBits.MessageContent,
      ],
    });
  }

  async start(token: string): Promise<void> {
    return new Promise<void>((resolve, reject) => {
      this.client.once("ready", () => {
        const user = this.client.user;
        logger.info({ tag: user?.tag ?? "unknown" }, "Bot logged in");
        logger.info({ guildCount: this.client.guilds.cache.size }, "Connected to guilds");
        this.setupMessageHandler();
        this.setupInteractionHandler();

        logger.debug("Message intent enabled, listening for messageCreate events");
        resolve();
      });

      this.client.once("error", reject);
      this.client.login(token).catch(reject);
    });
  }

  async registerCommands(): Promise<void> {
    const clientId = this.client.user?.id;
    if (!clientId) {
      throw new Error("Bot must be started before registering commands");
    }

    const claudeCommand = new SlashCommandBuilder()
      .setName("claude")
      .setDescription("Send a prompt to Claude")
      .addStringOption((option) =>
        option
          .setName("prompt")
          .setDescription("The prompt to send to Claude")
          .setRequired(true)
      );

    const claudeResetCommand = new SlashCommandBuilder()
      .setName("claude-reset")
      .setDescription("Reset the conversation session in this channel");

    const commands = [claudeCommand.toJSON(), claudeResetCommand.toJSON()];

    const rest = new REST({ version: "10" }).setToken(this.client.token!);
    await rest.put(Routes.applicationCommands(clientId), { body: commands });
    logger.info("Registered /claude and /claude-reset slash commands");
  }

  async sendMessage(channelId: string, content: string): Promise<void> {
    try {
      const channel = await this.client.channels.fetch(channelId);
      if (channel && "send" in channel) {
        await (channel as TextChannel).send(content);
      }
    } catch (error) {
      logger.error(
        { channelId, contentLength: content.length, err: error },
        "Failed to send message to channel",
      );
    }
  }

  async sendTyping(channelId: string): Promise<void> {
    try {
      const channel = await this.client.channels.fetch(channelId);
      if (channel && "sendTyping" in channel) {
        await (channel as TextChannel).sendTyping();
      }
    } catch {
      // Typing indicator failures are non-critical
    }
  }

  async destroy(): Promise<void> {
    await this.client.destroy();
  }

  onPrompt(handler: (prompt: Prompt) => void): void {
    this.promptHandler = handler;
  }

  onReset(handler: (channelId: string) => void): void {
    this.resetHandler = handler;
  }

  private setupMessageHandler(): void {
    this.client.on("messageCreate", (message: Message) => {
      logger.debug({ content: message.content, author: message.author.tag, bot: message.author.bot }, "Message received");

      if (shouldIgnoreMessage(message)) {
        logger.debug("Ignoring bot message");
        return;
      }

      const botUser = this.client.user;
      if (!botUser) {
        logger.debug("No bot user available");
        return;
      }

      if (!message.mentions.has(botUser)) {
        logger.debug("Message does not mention the bot");
        return;
      }

      const text = extractPromptFromMention(message.content, botUser.id);
      logger.debug({ text }, "Extracted prompt");
      if (!text) {
        logger.debug("Empty prompt after extraction, ignoring");
        return;
      }

      logger.debug({ text, channelId: message.channelId }, "Forwarding prompt to handler");
      this.promptHandler?.({
        text,
        channelId: message.channelId,
        userId: message.author.id,
        guildId: message.guildId,
      });
    });
  }

  private setupInteractionHandler(): void {
    this.client.on("interactionCreate", async (interaction) => {
      if (!interaction.isChatInputCommand()) return;

      const command = interaction as ChatInputCommandInteraction;

      if (command.commandName === "claude") {
        const promptText = command.options.getString("prompt", true);
        await command.deferReply();

        this.promptHandler?.({
          text: promptText,
          channelId: command.channelId,
          userId: command.user.id,
          guildId: command.guildId,
        });
      } else if (command.commandName === "claude-reset") {
        this.resetHandler?.(command.channelId);
        await command.reply({ content: "Session reset. Your next message will start a new conversation.", ephemeral: true });
      }
    });
  }
}