import { Message, ChannelType } from 'discord.js';
import BotClient from '@/services/Client';
import logger from '@/utils/logger';
import {
  makeAIRequest,
  getApiConfiguration,
  buildSystemPrompt,
  buildConversation,
  getUserCredentials,
  incrementAndCheckDailyLimit,
  incrementAndCheckServerDailyLimit,
  splitResponseIntoChunks,
  processUrls,
} from '@/commands/utilities/ai';
import type { ConversationMessage, AIResponse } from '@/commands/utilities/ai';

type ApiConfiguration = ReturnType<typeof getApiConfiguration>;
import { createMemoryManager } from '@/utils/memoryManager';

const serverConversations = createMemoryManager<string, ConversationMessage[]>({
  maxSize: 1000,
  maxAge: 2 * 60 * 60 * 1000,
  cleanupInterval: 10 * 60 * 1000,
});

const serverMessageContext = createMemoryManager<
  string,
  Array<{
    username: string;
    content: string;
    timestamp: number;
  }>
>({
  maxSize: 1000,
  maxAge: 2 * 60 * 60 * 1000,
  cleanupInterval: 10 * 60 * 1000,
});

const userConversations = createMemoryManager<string, ConversationMessage[]>({
  maxSize: 2000,
  maxAge: 2 * 60 * 60 * 1000,
  cleanupInterval: 10 * 60 * 1000,
});

function getServerConversationKey(guildId: string): string {
  return `server:${guildId}`;
}

function getUserConversationKey(userId: string): string {
  return `dm:${userId}`;
}

export default class MessageCreateEvent {
  constructor(private client: BotClient) {
    this.client = client;
    client.on('messageCreate', this.execute.bind(this));
  }

  private async execute(message: Message): Promise<void> {
    logger.debug(`Message received in channel type: ${message.channel.type}`);

    if (message.author.bot) {
      logger.debug('Ignoring message from bot');
      return;
    }

    const isDM = message.channel.type === ChannelType.DM;
    const isMentioned =
      message.mentions.users.has(this.client.user!.id) && !message.mentions.everyone;

    if (!isDM && message.guildId) {
      const contextKey = getServerConversationKey(message.guildId);
      const existingContext = serverMessageContext.get(contextKey) || [];

      const newMessage = {
        username: message.author.username,
        content: message.content,
        timestamp: Date.now(),
      };

      const updatedContext = [...existingContext, newMessage].slice(-10);
      serverMessageContext.set(contextKey, updatedContext);
    }

    if (!isDM && !isMentioned) {
      logger.debug(
        `Storing message for context but not responding - not a DM and bot not mentioned (channel type: ${message.channel.type})`,
      );
      return;
    }

    logger.info(isDM ? 'Processing DM message...' : 'Processing mention in server...');

    try {
      logger.debug(
        `${isDM ? 'DM' : 'Message'} received (${message.content.length} characters) - content hidden for privacy`,
      );

      const hasImageAttachments = message.attachments.some(
        (att) =>
          att.contentType?.startsWith('image/') ||
          att.name?.match(/\.(jpg|jpeg|png|gif|webp|bmp|svg)$/i),
      );

      logger.debug(`hasImageAttachments: ${hasImageAttachments}`);
      const hasImages = hasImageAttachments;

      let selectedModel: string;
      let config: ApiConfiguration;
      let usingDefaultKey = true;

      if (isDM) {
        const {
          model: userCustomModel,
          apiKey: userApiKey,
          apiUrl: userApiUrl,
        } = await getUserCredentials(`user:${message.author.id}`);

        selectedModel = hasImages
          ? 'google/gemma-3-4b-it'
          : userCustomModel || 'moonshotai/kimi-k2';

        config = getApiConfiguration(userApiKey ?? null, selectedModel, userApiUrl ?? null);
        usingDefaultKey = config.usingDefaultKey;
      } else {
        selectedModel = hasImages ? 'google/gemma-3-4b-it' : 'google/gemini-2.5-flash-lite';

        config = getApiConfiguration(null, selectedModel, null);
      }

      logger.info(
        `Using model: ${selectedModel} for message with images: ${hasImages}${
          isDM && !usingDefaultKey ? ' (user custom model)' : ' (default model)'
        }`,
      );

      const systemPrompt = buildSystemPrompt(
        usingDefaultKey,
        this.client,
        selectedModel,
        message.author.username,
        undefined,
        !isDM,
        !isDM ? message.guild?.name : undefined,
      );

      let messageContent:
        | string
        | Array<{
            type: 'text' | 'image_url';
            text?: string;
            image_url?: {
              url: string;
              detail?: 'low' | 'high' | 'auto';
            };
          }> = isDM ? message.content : message.content.replace(/<@!?\d+>/g, '').trim();

      if (hasImages) {
        const imageAttachments = message.attachments.filter(
          (att) =>
            att.contentType?.startsWith('image/') ||
            att.name?.match(/\.(jpg|jpeg|png|gif|webp|bmp|svg)$/i),
        );

        const contentArray: Array<{
          type: 'text' | 'image_url';
          text?: string;
          image_url?: {
            url: string;
            detail?: 'low' | 'high' | 'auto';
          };
        }> = [];

        const cleanContent = isDM
          ? message.content
          : message.content.replace(/<@!?\d+>/g, '').trim();
        if (cleanContent.trim()) {
          contentArray.push({
            type: 'text',
            text: cleanContent,
          });
        }

        imageAttachments.forEach((att) => {
          contentArray.push({
            type: 'image_url',
            image_url: {
              url: att.url,
              detail: 'auto',
            },
          });
        });

        messageContent = contentArray;
      }

      let conversation: ConversationMessage[] = [];

      if (isDM) {
        const conversationKey = getUserConversationKey(message.author.id);
        conversation = userConversations.get(conversationKey) || [];
      } else {
        const serverKey = getServerConversationKey(message.guildId!);
        const serverConversation = serverConversations.get(serverKey) || [];
        const recentMessages = serverMessageContext.get(serverKey) || [];

        const contextMessages = recentMessages.slice(-6, -1).map((msg) => ({
          role: 'user' as const,
          content: `**${msg.username}**: ${msg.content}`,
          username: msg.username,
        }));

        const aiHistory = serverConversation.slice(-3);

        const formattedAiHistory = aiHistory.map((msg) => {
          if (msg.role === 'user' && msg.username) {
            const content = Array.isArray(msg.content)
              ? msg.content.map((c) => (c.type === 'text' ? c.text : '[Image]')).join(' ')
              : msg.content;
            return {
              ...msg,
              content: `**${msg.username}**: ${content}`,
            };
          }
          return msg;
        });

        conversation = [...contextMessages, ...formattedAiHistory];
      }

      let filteredConversation = conversation;
      if (selectedModel === 'moonshotai/kimi-k2') {
        filteredConversation = conversation.map((msg) => {
          if (Array.isArray(msg.content)) {
            const textContent = msg.content
              .filter((item) => item.type === 'text')
              .map((item) => item.text)
              .join(' ');
            return { ...msg, content: textContent || '[Image content]' };
          }
          return msg;
        });
      }

      const updatedConversation = buildConversation(
        filteredConversation,
        messageContent,
        systemPrompt,
      );

      if (config.usingDefaultKey) {
        const exemptUserId = process.env.AI_EXEMPT_USER_ID;
        const actorId = message.author.id;

        if (actorId !== exemptUserId) {
          if (isDM) {
            const allowed = await incrementAndCheckDailyLimit(actorId, 10);
            if (!allowed) {
              await message.reply(
                "❌ You've reached your daily limit of AI requests. Please try again tomorrow or set up your own API key using the `/ai` command.",
              );
              return;
            }
          } else {
            let serverLimit = 30;
            try {
              const memberCount = message.guild?.memberCount || 0;
              if (memberCount >= 1000) {
                serverLimit = 500;
              } else if (memberCount >= 100) {
                serverLimit = 150;
              }

              const serverAllowed = await incrementAndCheckServerDailyLimit(
                message.guildId!,
                serverLimit,
              );
              if (!serverAllowed) {
                await message.reply(
                  `❌ This server has reached its daily limit of ${serverLimit} AI requests. Please try again tomorrow.`,
                );
                return;
              }
            } catch (error) {
              logger.error('Error checking server member count:', error);
              const serverAllowed = await incrementAndCheckServerDailyLimit(message.guildId!, 30);
              if (!serverAllowed) {
                await message.reply(
                  '❌ This server has reached its daily limit of AI requests. Please try again tomorrow.',
                );
                return;
              }
            }
          }
        }
      } else if (!config.finalApiKey) {
        await message.reply('❌ Please set up your API key first using the `/ai` command.');
        return;
      }

      let aiResponse = await makeAIRequest(config, updatedConversation);

      if (!aiResponse && hasImages) {
        logger.warn(`First attempt failed for ${selectedModel}, retrying once...`);
        await new Promise((resolve) => setTimeout(resolve, 1000));
        aiResponse = await makeAIRequest(config, updatedConversation);
      }

      if (!aiResponse && hasImages) {
        logger.warn(`Image model ${selectedModel} failed, falling back to text-only model`);

        let fallbackContent = message.content;
        if (Array.isArray(messageContent)) {
          const textParts = messageContent
            .filter((item) => item.type === 'text')
            .map((item) => item.text)
            .filter((text) => text && text.trim());

          const imageParts = messageContent
            .filter((item) => item.type === 'image_url')
            .map((item) => `[Image: ${item.image_url?.url}]`);

          fallbackContent =
            [...textParts, ...imageParts].join(' ') ||
            `[Message contained images that could not be processed: ${message.content}]`;
        }

        const cleanedConversation = conversation.map((msg) => {
          if (Array.isArray(msg.content)) {
            const textContent = msg.content
              .filter((item) => item.type === 'text')
              .map((item) => item.text)
              .join(' ');
            return { ...msg, content: textContent || '[Image content]' };
          }
          return msg;
        });

        const fallbackModel =
          isDM && !usingDefaultKey
            ? 'moonshotai/kimi-k2'
            : isDM
              ? 'moonshotai/kimi-k2'
              : 'google/gemini-2.5-flash-lite';

        const fallbackConversation = buildConversation(
          cleanedConversation,
          fallbackContent,
          buildSystemPrompt(
            usingDefaultKey,
            this.client,
            fallbackModel,
            message.author.username,
            undefined,
            !isDM,
            !isDM ? message.guild?.name : undefined,
          ),
        );

        const fallbackConfig = isDM ? config : getApiConfiguration(null, fallbackModel, null);
        aiResponse = await makeAIRequest(fallbackConfig, fallbackConversation);

        if (aiResponse) {
          logger.info('Successfully processed message with fallback text-only model');
        }
      }

      if (!aiResponse) {
        await message.reply({
          content: 'Sorry, I encountered an error processing your message. Please try again later.',
          allowedMentions: { parse: ['users'] as const },
        });
        return;
      }

      aiResponse.content = processUrls(aiResponse.content);
      aiResponse.content = aiResponse.content.replace(/@(everyone|here)/gi, '@\u200b$1');

      const { getUnallowedWordCategory } = await import('@/utils/validation');
      const category = getUnallowedWordCategory(aiResponse.content);
      if (category) {
        logger.warn(`AI response contained unallowed words in category: ${category}`);
        await message.reply({
          content:
            'Sorry, I cannot provide that response as it contains prohibited content. Please try a different prompt.',
          allowedMentions: { parse: ['users'] as const },
        });
        return;
      }

      await this.sendResponse(message, aiResponse);

      const userMessage: ConversationMessage = {
        role: 'user',
        content: messageContent,
        username: message.author.username,
      };
      const assistantMessage: ConversationMessage = {
        role: 'assistant',
        content: aiResponse.content,
      };

      if (isDM) {
        const conversationKey = getUserConversationKey(message.author.id);
        const newConversation = [...filteredConversation, userMessage, assistantMessage];
        userConversations.set(conversationKey, newConversation);
      } else {
        const serverKey = getServerConversationKey(message.guildId!);
        const serverConversation = serverConversations.get(serverKey) || [];
        const newServerConversation = [...serverConversation, userMessage, assistantMessage];
        serverConversations.set(serverKey, newServerConversation);
      }

      logger.info(`${isDM ? 'DM' : 'Server'} response sent successfully`);
    } catch (error) {
      logger.error(
        `Error processing ${isDM ? 'DM' : 'server message'}:`,
        error instanceof Error ? error.message : String(error),
      );
      try {
        await message.reply(
          'Sorry, I encountered an error processing your message. Please try again later.',
        );
      } catch (replyError) {
        logger.error('Failed to send error message:', replyError);
      }
    }
  }

  private async sendResponse(message: Message, aiResponse: AIResponse): Promise<void> {
    let fullResponse = '';

    if (aiResponse.reasoning) {
      fullResponse += `> ${aiResponse.reasoning}\n\n`;
    }

    fullResponse += aiResponse.content;

    const maxLength = 2000;
    if (fullResponse.length <= maxLength) {
      await message.reply({
        content: fullResponse,
        allowedMentions: { parse: ['users'] as const },
      });
    } else {
      const chunks = splitResponseIntoChunks(fullResponse, maxLength);

      await message.reply({ content: chunks[0], allowedMentions: { parse: ['users'] as const } });

      for (let i = 1; i < chunks.length; i++) {
        if ('send' in message.channel) {
          await message.channel.send({
            content: chunks[i],
            allowedMentions: { parse: ['users'] as const },
          });
        }
      }
    }
  }
}