import { Injectable, Logger, Optional, Inject } from "@nestjs/common";
import { MatrixClient, SimpleFsStorageProvider, AutojoinRoomsMixin } from "matrix-bot-sdk";
import { StitcherService } from "../../stitcher/stitcher.service";
import { CommandParserService } from "../parser/command-parser.service";
import { CommandAction } from "../parser/command.interface";
import type { ParsedCommand } from "../parser/command.interface";
import { MatrixRoomService } from "./matrix-room.service";
import { sanitizeForLogging } from "../../common/utils";
import type {
  IChatProvider,
  ChatMessage,
  ChatCommand,
  ThreadCreateOptions,
  ThreadMessageOptions,
} from "../interfaces";

/**
 * Matrix room message event content
 */
interface MatrixMessageContent {
  msgtype: string;
  body: string;
  "m.relates_to"?: MatrixRelatesTo;
}

/**
 * Matrix relationship metadata for threads (MSC3440)
 */
interface MatrixRelatesTo {
  rel_type: string;
  event_id: string;
  is_falling_back?: boolean;
  "m.in_reply_to"?: {
    event_id: string;
  };
}

/**
 * Matrix room event structure
 */
interface MatrixRoomEvent {
  event_id: string;
  sender: string;
  origin_server_ts: number;
  content: MatrixMessageContent;
}

/**
 * Matrix Service - Matrix chat platform integration
 *
 * Responsibilities:
 * - Connect to Matrix via access token
 * - Listen for commands in mapped rooms (via MatrixRoomService)
 * - Parse commands using shared CommandParserService
 * - Forward commands to stitcher
 * - Receive status updates from herald
 * - Post updates to threads (MSC3440)
 */
@Injectable()
export class MatrixService implements IChatProvider {
  private readonly logger = new Logger(MatrixService.name);
  private client: MatrixClient | null = null;
  private connected = false;
  private readonly homeserverUrl: string;
  private readonly accessToken: string;
  private readonly botUserId: string;
  private readonly controlRoomId: string;
  private readonly workspaceId: string;

  constructor(
    private readonly stitcherService: StitcherService,
    @Optional()
    @Inject(CommandParserService)
    private readonly commandParser: CommandParserService | null,
    @Optional()
    @Inject(MatrixRoomService)
    private readonly matrixRoomService: MatrixRoomService | null
  ) {
    this.homeserverUrl = process.env.MATRIX_HOMESERVER_URL ?? "";
    this.accessToken = process.env.MATRIX_ACCESS_TOKEN ?? "";
    this.botUserId = process.env.MATRIX_BOT_USER_ID ?? "";
    this.controlRoomId = process.env.MATRIX_CONTROL_ROOM_ID ?? "";
    this.workspaceId = process.env.MATRIX_WORKSPACE_ID ?? "";
  }

  /**
   * Connect to Matrix homeserver
   */
  async connect(): Promise<void> {
    if (!this.homeserverUrl) {
      throw new Error("MATRIX_HOMESERVER_URL is required");
    }

    if (!this.accessToken) {
      throw new Error("MATRIX_ACCESS_TOKEN is required");
    }

    if (!this.workspaceId) {
      throw new Error("MATRIX_WORKSPACE_ID is required");
    }

    if (!this.botUserId) {
      throw new Error("MATRIX_BOT_USER_ID is required");
    }

    this.logger.log("Connecting to Matrix...");

    const storage = new SimpleFsStorageProvider("matrix-bot-storage.json");
    this.client = new MatrixClient(this.homeserverUrl, this.accessToken, storage);

    // Auto-join rooms when invited
    AutojoinRoomsMixin.setupOnClient(this.client);

    // Setup event handlers
    this.setupEventHandlers();

    // Start syncing
    await this.client.start();
    this.connected = true;
    this.logger.log(`Matrix bot connected as ${this.botUserId}`);
  }

  /**
   * Setup event handlers for Matrix client
   */
  private setupEventHandlers(): void {
    if (!this.client) return;

    this.client.on("room.message", (roomId: string, event: MatrixRoomEvent) => {
      // Ignore messages from the bot itself
      if (event.sender === this.botUserId) return;

      // Only handle text messages
      if (event.content.msgtype !== "m.text") return;

      this.handleRoomMessage(roomId, event).catch((error: unknown) => {
        this.logger.error(
          `Error handling room message in ${roomId}:`,
          error instanceof Error ? error.message : error
        );
      });
    });

    this.client.on("room.event", (_roomId: string, event: MatrixRoomEvent | null) => {
      // Handle errors emitted as events
      if (!event) {
        const error = new Error("Received null event from Matrix");
        const sanitizedError = sanitizeForLogging(error);
        this.logger.error("Matrix client error:", sanitizedError);
      }
    });
  }

  /**
   * Handle an incoming room message.
   *
   * Resolves the workspace for the room (via MatrixRoomService or fallback
   * to the control room), then delegates to the shared CommandParserService
   * for platform-agnostic command parsing and dispatches the result.
   */
  private async handleRoomMessage(roomId: string, event: MatrixRoomEvent): Promise<void> {
    // Resolve workspace: try MatrixRoomService first, fall back to control room
    let resolvedWorkspaceId: string | null = null;

    if (this.matrixRoomService) {
      resolvedWorkspaceId = await this.matrixRoomService.getWorkspaceForRoom(roomId);
    }

    // Fallback: if the room is the configured control room, use the env workspace
    if (!resolvedWorkspaceId && roomId === this.controlRoomId) {
      resolvedWorkspaceId = this.workspaceId;
    }

    // If room is not mapped to any workspace, ignore the message
    if (!resolvedWorkspaceId) {
      return;
    }

    const messageContent = event.content.body;

    // Build ChatMessage for interface compatibility
    const chatMessage: ChatMessage = {
      id: event.event_id,
      channelId: roomId,
      authorId: event.sender,
      authorName: event.sender,
      content: messageContent,
      timestamp: new Date(event.origin_server_ts),
      ...(event.content["m.relates_to"]?.rel_type === "m.thread" && {
        threadId: event.content["m.relates_to"].event_id,
      }),
    };

    // Use shared CommandParserService if available
    if (this.commandParser) {
      // Normalize !mosaic to @mosaic for the shared parser
      const normalizedContent = messageContent.replace(/^!mosaic/i, "@mosaic");

      const result = this.commandParser.parseCommand(normalizedContent);

      if (result.success) {
        await this.handleParsedCommand(result.command, chatMessage, resolvedWorkspaceId);
      } else if (normalizedContent.toLowerCase().startsWith("@mosaic")) {
        // The user tried to use a command but it failed to parse -- send help
        await this.sendMessage(roomId, result.error.help ?? result.error.message);
      }
      return;
    }

    // Fallback: use the built-in parseCommand if CommandParserService not injected
    const command = this.parseCommand(chatMessage);
    if (command) {
      await this.handleCommand(command);
    }
  }

  /**
   * Handle a command parsed by the shared CommandParserService.
   *
   * Routes the ParsedCommand to the appropriate handler, passing
   * along workspace context for job dispatch.
   */
  private async handleParsedCommand(
    parsed: ParsedCommand,
    message: ChatMessage,
    workspaceId: string
  ): Promise<void> {
    this.logger.log(
      `Handling command: ${parsed.action} from ${message.authorName} in workspace ${workspaceId}`
    );

    switch (parsed.action) {
      case CommandAction.FIX:
        await this.handleFixCommand(parsed.rawArgs, message, workspaceId);
        break;
      case CommandAction.STATUS:
        await this.handleStatusCommand(parsed.rawArgs, message);
        break;
      case CommandAction.CANCEL:
        await this.handleCancelCommand(parsed.rawArgs, message);
        break;
      case CommandAction.VERBOSE:
        await this.handleVerboseCommand(parsed.rawArgs, message);
        break;
      case CommandAction.QUIET:
        await this.handleQuietCommand(parsed.rawArgs, message);
        break;
      case CommandAction.HELP:
        await this.handleHelpCommand(parsed.rawArgs, message);
        break;
      case CommandAction.RETRY:
        await this.handleRetryCommand(parsed.rawArgs, message);
        break;
      default:
        await this.sendMessage(
          message.channelId,
          `Unknown command. Type \`@mosaic help\` or \`!mosaic help\` for available commands.`
        );
    }
  }

  /**
   * Disconnect from Matrix
   */
  disconnect(): Promise<void> {
    this.logger.log("Disconnecting from Matrix...");
    this.connected = false;
    if (this.client) {
      this.client.stop();
    }
    return Promise.resolve();
  }

  /**
   * Check if the provider is connected
   */
  isConnected(): boolean {
    return this.connected;
  }

  /**
   * Get the underlying MatrixClient instance.
   *
   * Used by MatrixStreamingService for low-level operations
   * (message edits, typing indicators) that require direct client access.
   *
   * @returns The MatrixClient instance, or null if not connected
   */
  getClient(): MatrixClient | null {
    return this.client;
  }

  /**
   * Send a message to a room
   */
  async sendMessage(roomId: string, content: string): Promise<void> {
    if (!this.client) {
      throw new Error("Matrix client is not connected");
    }

    const messageContent: MatrixMessageContent = {
      msgtype: "m.text",
      body: content,
    };

    await this.client.sendMessage(roomId, messageContent);
  }

  /**
   * Create a thread for job updates (MSC3440)
   *
   * Matrix threads are created by sending an initial message
   * and then replying with m.thread relation. The initial
   * message event ID becomes the thread root.
   */
  async createThread(options: ThreadCreateOptions): Promise<string> {
    if (!this.client) {
      throw new Error("Matrix client is not connected");
    }

    const { channelId, name, message } = options;

    // Send the initial message that becomes the thread root
    const initialContent: MatrixMessageContent = {
      msgtype: "m.text",
      body: `[${name}] ${message}`,
    };

    const eventId = await this.client.sendMessage(channelId, initialContent);

    return eventId;
  }

  /**
   * Send a message to a thread (MSC3440)
   *
   * Uses m.thread relation to associate the message with the thread root event.
   */
  async sendThreadMessage(options: ThreadMessageOptions): Promise<void> {
    if (!this.client) {
      throw new Error("Matrix client is not connected");
    }

    const { threadId, channelId, content } = options;

    // Use the channelId from options (threads are room-scoped), fall back to control room
    const roomId = channelId || this.controlRoomId;

    const threadContent: MatrixMessageContent = {
      msgtype: "m.text",
      body: content,
      "m.relates_to": {
        rel_type: "m.thread",
        event_id: threadId,
        is_falling_back: true,
        "m.in_reply_to": {
          event_id: threadId,
        },
      },
    };

    await this.client.sendMessage(roomId, threadContent);
  }

  /**
   * Parse a command from a message (IChatProvider interface).
   *
   * Delegates to the shared CommandParserService when available,
   * falling back to built-in parsing for backwards compatibility.
   */
  parseCommand(message: ChatMessage): ChatCommand | null {
    const { content } = message;

    // Try shared parser first
    if (this.commandParser) {
      const normalizedContent = content.replace(/^!mosaic/i, "@mosaic");
      const result = this.commandParser.parseCommand(normalizedContent);

      if (result.success) {
        return {
          command: result.command.action,
          args: result.command.rawArgs,
          message,
        };
      }
      return null;
    }

    // Fallback: built-in parsing for when CommandParserService is not injected
    const lowerContent = content.toLowerCase();
    if (!lowerContent.includes("@mosaic") && !lowerContent.includes("!mosaic")) {
      return null;
    }

    const parts = content.trim().split(/\s+/);
    const mosaicIndex = parts.findIndex(
      (part) => part.toLowerCase().includes("@mosaic") || part.toLowerCase().includes("!mosaic")
    );

    if (mosaicIndex === -1 || mosaicIndex === parts.length - 1) {
      return null;
    }

    const commandPart = parts[mosaicIndex + 1];
    if (!commandPart) {
      return null;
    }

    const command = commandPart.toLowerCase();
    const args = parts.slice(mosaicIndex + 2);

    const validCommands = ["fix", "status", "cancel", "verbose", "quiet", "help"];

    if (!validCommands.includes(command)) {
      return null;
    }

    return {
      command,
      args,
      message,
    };
  }

  /**
   * Handle a parsed command (ChatCommand format, used by fallback path)
   */
  async handleCommand(command: ChatCommand): Promise<void> {
    const { command: cmd, args, message } = command;

    this.logger.log(
      `Handling command: ${cmd} with args: ${args.join(", ")} from ${message.authorName}`
    );

    switch (cmd) {
      case "fix":
        await this.handleFixCommand(args, message, this.workspaceId);
        break;
      case "status":
        await this.handleStatusCommand(args, message);
        break;
      case "cancel":
        await this.handleCancelCommand(args, message);
        break;
      case "verbose":
        await this.handleVerboseCommand(args, message);
        break;
      case "quiet":
        await this.handleQuietCommand(args, message);
        break;
      case "help":
        await this.handleHelpCommand(args, message);
        break;
      default:
        await this.sendMessage(
          message.channelId,
          `Unknown command: ${cmd}. Type \`@mosaic help\` or \`!mosaic help\` for available commands.`
        );
    }
  }

  /**
   * Handle fix command - Start a job for an issue
   */
  private async handleFixCommand(
    args: string[],
    message: ChatMessage,
    workspaceId?: string
  ): Promise<void> {
    if (args.length === 0 || !args[0]) {
      await this.sendMessage(
        message.channelId,
        "Usage: `@mosaic fix <issue-number>` or `!mosaic fix <issue-number>`"
      );
      return;
    }

    // Parse issue number: handle both "#42" and "42" formats
    const issueArg = args[0].replace(/^#/, "");
    const issueNumber = parseInt(issueArg, 10);

    if (isNaN(issueNumber)) {
      await this.sendMessage(
        message.channelId,
        "Invalid issue number. Please provide a numeric issue number."
      );
      return;
    }

    const targetWorkspaceId = workspaceId ?? this.workspaceId;

    // Create thread for job updates
    const threadId = await this.createThread({
      channelId: message.channelId,
      name: `Job #${String(issueNumber)}`,
      message: `Starting job for issue #${String(issueNumber)}...`,
    });

    // Dispatch job to stitcher
    try {
      const result = await this.stitcherService.dispatchJob({
        workspaceId: targetWorkspaceId,
        type: "code-task",
        priority: 10,
        metadata: {
          issueNumber,
          command: "fix",
          channelId: message.channelId,
          threadId: threadId,
          authorId: message.authorId,
          authorName: message.authorName,
        },
      });

      // Send confirmation to thread
      await this.sendThreadMessage({
        threadId,
        channelId: message.channelId,
        content: `Job created: ${result.jobId}\nStatus: ${result.status}\nQueue: ${result.queueName}`,
      });
    } catch (error: unknown) {
      const errorMessage = error instanceof Error ? error.message : "Unknown error";
      this.logger.error(
        `Failed to dispatch job for issue #${String(issueNumber)}: ${errorMessage}`
      );
      await this.sendThreadMessage({
        threadId,
        channelId: message.channelId,
        content: `Failed to start job: ${errorMessage}`,
      });
    }
  }

  /**
   * Handle status command - Get job status
   */
  private async handleStatusCommand(args: string[], message: ChatMessage): Promise<void> {
    if (args.length === 0 || !args[0]) {
      await this.sendMessage(
        message.channelId,
        "Usage: `@mosaic status <job-id>` or `!mosaic status <job-id>`"
      );
      return;
    }

    const jobId = args[0];

    // TODO: Implement job status retrieval from stitcher
    await this.sendMessage(
      message.channelId,
      `Status command not yet implemented for job: ${jobId}`
    );
  }

  /**
   * Handle cancel command - Cancel a running job
   */
  private async handleCancelCommand(args: string[], message: ChatMessage): Promise<void> {
    if (args.length === 0 || !args[0]) {
      await this.sendMessage(
        message.channelId,
        "Usage: `@mosaic cancel <job-id>` or `!mosaic cancel <job-id>`"
      );
      return;
    }

    const jobId = args[0];

    // TODO: Implement job cancellation in stitcher
    await this.sendMessage(
      message.channelId,
      `Cancel command not yet implemented for job: ${jobId}`
    );
  }

  /**
   * Handle retry command - Retry a failed job
   */
  private async handleRetryCommand(args: string[], message: ChatMessage): Promise<void> {
    if (args.length === 0 || !args[0]) {
      await this.sendMessage(
        message.channelId,
        "Usage: `@mosaic retry <job-id>` or `!mosaic retry <job-id>`"
      );
      return;
    }

    const jobId = args[0];

    // TODO: Implement job retry in stitcher
    await this.sendMessage(
      message.channelId,
      `Retry command not yet implemented for job: ${jobId}`
    );
  }

  /**
   * Handle verbose command - Stream full logs to thread
   */
  private async handleVerboseCommand(args: string[], message: ChatMessage): Promise<void> {
    if (args.length === 0 || !args[0]) {
      await this.sendMessage(
        message.channelId,
        "Usage: `@mosaic verbose <job-id>` or `!mosaic verbose <job-id>`"
      );
      return;
    }

    const jobId = args[0];

    // TODO: Implement verbose logging
    await this.sendMessage(message.channelId, `Verbose mode not yet implemented for job: ${jobId}`);
  }

  /**
   * Handle quiet command - Reduce notifications
   */
  private async handleQuietCommand(_args: string[], message: ChatMessage): Promise<void> {
    // TODO: Implement quiet mode
    await this.sendMessage(
      message.channelId,
      "Quiet mode not yet implemented. Currently showing milestone updates only."
    );
  }

  /**
   * Handle help command - Show available commands
   */
  private async handleHelpCommand(_args: string[], message: ChatMessage): Promise<void> {
    const helpMessage = `
**Available commands:**

\`@mosaic fix <issue>\` or \`!mosaic fix <issue>\` - Start job for issue
\`@mosaic status <job>\` or \`!mosaic status <job>\` - Get job status
\`@mosaic cancel <job>\` or \`!mosaic cancel <job>\` - Cancel running job
\`@mosaic retry <job>\` or \`!mosaic retry <job>\` - Retry failed job
\`@mosaic verbose <job>\` or \`!mosaic verbose <job>\` - Stream full logs to thread
\`@mosaic quiet\` or \`!mosaic quiet\` - Reduce notifications
\`@mosaic help\` or \`!mosaic help\` - Show this help message

**Noise Management:**
- Main room: Low verbosity (milestones only)
- Job threads: Medium verbosity (step completions)
- DMs: Configurable per user
    `.trim();

    await this.sendMessage(message.channelId, helpMessage);
  }
}