import * as plugins from '../tsmdb.plugins.js';
import type { IStorageAdapter } from '../storage/IStorageAdapter.js';
import type { IParsedCommand } from './WireProtocol.js';
import type { TsmdbServer } from './TsmdbServer.js';

// Import handlers
import { HelloHandler } from './handlers/HelloHandler.js';
import { InsertHandler } from './handlers/InsertHandler.js';
import { FindHandler } from './handlers/FindHandler.js';
import { UpdateHandler } from './handlers/UpdateHandler.js';
import { DeleteHandler } from './handlers/DeleteHandler.js';
import { AggregateHandler } from './handlers/AggregateHandler.js';
import { IndexHandler } from './handlers/IndexHandler.js';
import { AdminHandler } from './handlers/AdminHandler.js';

/**
 * Handler context passed to command handlers
 */
export interface IHandlerContext {
  storage: IStorageAdapter;
  server: TsmdbServer;
  database: string;
  command: plugins.bson.Document;
  documentSequences?: Map<string, plugins.bson.Document[]>;
}

/**
 * Command handler interface
 */
export interface ICommandHandler {
  handle(context: IHandlerContext): Promise<plugins.bson.Document>;
}

/**
 * CommandRouter - Routes incoming commands to appropriate handlers
 */
export class CommandRouter {
  private storage: IStorageAdapter;
  private server: TsmdbServer;
  private handlers: Map<string, ICommandHandler> = new Map();

  // Cursor state for getMore operations
  private cursors: Map<bigint, ICursorState> = new Map();
  private cursorIdCounter: bigint = BigInt(1);

  constructor(storage: IStorageAdapter, server: TsmdbServer) {
    this.storage = storage;
    this.server = server;
    this.registerHandlers();
  }

  /**
   * Register all command handlers
   */
  private registerHandlers(): void {
    // Create handler instances with shared state
    const helloHandler = new HelloHandler();
    const findHandler = new FindHandler(this.cursors, () => this.cursorIdCounter++);
    const insertHandler = new InsertHandler();
    const updateHandler = new UpdateHandler();
    const deleteHandler = new DeleteHandler();
    const aggregateHandler = new AggregateHandler(this.cursors, () => this.cursorIdCounter++);
    const indexHandler = new IndexHandler();
    const adminHandler = new AdminHandler();

    // Handshake commands
    this.handlers.set('hello', helloHandler);
    this.handlers.set('ismaster', helloHandler);
    this.handlers.set('isMaster', helloHandler);

    // CRUD commands
    this.handlers.set('find', findHandler);
    this.handlers.set('insert', insertHandler);
    this.handlers.set('update', updateHandler);
    this.handlers.set('delete', deleteHandler);
    this.handlers.set('findAndModify', updateHandler);
    this.handlers.set('getMore', findHandler);
    this.handlers.set('killCursors', findHandler);

    // Aggregation
    this.handlers.set('aggregate', aggregateHandler);
    this.handlers.set('count', findHandler);
    this.handlers.set('distinct', findHandler);

    // Index operations
    this.handlers.set('createIndexes', indexHandler);
    this.handlers.set('dropIndexes', indexHandler);
    this.handlers.set('listIndexes', indexHandler);

    // Admin/Database operations
    this.handlers.set('ping', adminHandler);
    this.handlers.set('listDatabases', adminHandler);
    this.handlers.set('listCollections', adminHandler);
    this.handlers.set('drop', adminHandler);
    this.handlers.set('dropDatabase', adminHandler);
    this.handlers.set('create', adminHandler);
    this.handlers.set('serverStatus', adminHandler);
    this.handlers.set('buildInfo', adminHandler);
    this.handlers.set('whatsmyuri', adminHandler);
    this.handlers.set('getLog', adminHandler);
    this.handlers.set('hostInfo', adminHandler);
    this.handlers.set('replSetGetStatus', adminHandler);
    this.handlers.set('isMaster', helloHandler);
    this.handlers.set('saslStart', adminHandler);
    this.handlers.set('saslContinue', adminHandler);
    this.handlers.set('endSessions', adminHandler);
    this.handlers.set('abortTransaction', adminHandler);
    this.handlers.set('commitTransaction', adminHandler);
    this.handlers.set('collStats', adminHandler);
    this.handlers.set('dbStats', adminHandler);
    this.handlers.set('connectionStatus', adminHandler);
    this.handlers.set('currentOp', adminHandler);
    this.handlers.set('collMod', adminHandler);
    this.handlers.set('renameCollection', adminHandler);
  }

  /**
   * Route a command to its handler
   */
  async route(parsedCommand: IParsedCommand): Promise<plugins.bson.Document> {
    const { commandName, command, database, documentSequences } = parsedCommand;

    // Create handler context
    const context: IHandlerContext = {
      storage: this.storage,
      server: this.server,
      database,
      command,
      documentSequences,
    };

    // Find handler
    const handler = this.handlers.get(commandName);

    if (!handler) {
      // Unknown command
      return {
        ok: 0,
        errmsg: `no such command: '${commandName}'`,
        code: 59,
        codeName: 'CommandNotFound',
      };
    }

    try {
      return await handler.handle(context);
    } catch (error: any) {
      // Handle known error types
      if (error.code) {
        return {
          ok: 0,
          errmsg: error.message,
          code: error.code,
          codeName: error.codeName || 'UnknownError',
        };
      }

      // Generic error
      return {
        ok: 0,
        errmsg: error.message || 'Internal error',
        code: 1,
        codeName: 'InternalError',
      };
    }
  }
}

/**
 * Cursor state for multi-batch queries
 */
export interface ICursorState {
  id: bigint;
  database: string;
  collection: string;
  documents: plugins.bson.Document[];
  position: number;
  batchSize: number;
  createdAt: Date;
}