import { Collection, Db, MongoClient, OptionalUnlessRequiredId } from 'mongodb';
import { getLogger } from '@stock-bot/logger';
import type { DocumentBase, MongoDBClientConfig } from './types';

/**
 * MongoDB Client for Stock Bot Data Service
 *
 * MongoDB client focused on batch upsert operations
 * with minimal configuration and no health monitoring complexity.
 */
export class MongoDBClient {
  private client: MongoClient | null = null;
  private db: Db | null = null;
  private readonly config: MongoDBClientConfig;
  private defaultDatabase: string;
  private readonly logger = getLogger('mongodb-client');
  private isConnected = false;

  constructor(config: MongoDBClientConfig) {
    this.config = config;
    this.defaultDatabase = config.database || 'stock';
  }

  /**
   * Connect to MongoDB with simple configuration
   */
  async connect(): Promise<void> {
    if (this.isConnected && this.client) {
      return;
    }

    try {
      const uri = this.buildConnectionUri();
      this.logger.info('Connecting to MongoDB...');

      this.client = new MongoClient(uri, {
        maxPoolSize: this.config.poolSettings?.maxPoolSize || 10,
        minPoolSize: this.config.poolSettings?.minPoolSize || 1,
        connectTimeoutMS: this.config.timeouts?.connectTimeout || 10000,
        socketTimeoutMS: this.config.timeouts?.socketTimeout || 30000,
        serverSelectionTimeoutMS: this.config.timeouts?.serverSelectionTimeout || 5000,
      });

      await this.client.connect();
      await this.client.db(this.defaultDatabase).admin().ping();

      // Set default database from config
      this.db = this.client.db(this.defaultDatabase);
      this.isConnected = true;

      this.logger.info('Successfully connected to MongoDB');
    } catch (error) {
      this.logger.error('MongoDB connection failed:', error);
      if (this.client) {
        await this.client.close();
        this.client = null;
      }
      throw error;
    }
  }

  /**
   * Disconnect from MongoDB
   */
  async disconnect(): Promise<void> {
    if (!this.client) {
      return;
    }

    try {
      await this.client.close();
      this.isConnected = false;
      this.client = null;
      this.db = null;
      this.logger.info('Disconnected from MongoDB');
    } catch (error) {
      this.logger.error('Error disconnecting from MongoDB:', error);
      throw error;
    }
  }

  /**
   * Set the default database for operations
   */
  setDefaultDatabase(databaseName: string): void {
    this.defaultDatabase = databaseName;
    if (this.client) {
      this.db = this.client.db(databaseName);
      this.logger.debug(`Default database changed to: ${databaseName}`);
    }
  }

  /**
   * Get the current default database name
   */
  getDefaultDatabase(): string {
    return this.defaultDatabase;
  }

  /**
   * Get a database instance by name
   */
  getDatabase(databaseName?: string): Db {
    if (!this.client) {
      throw new Error('MongoDB client not connected');
    }

    const dbName = databaseName || this.defaultDatabase;
    return this.client.db(dbName);
  }

  /**
   * Batch upsert documents for high-performance operations
   * Supports single or multiple unique keys for matching
   */
  async batchUpsert<T extends DocumentBase>(
    collectionName: string,
    documents: Array<
      Omit<T, '_id' | 'created_at' | 'updated_at'> & Partial<Pick<T, 'created_at' | 'updated_at'>>
    >,
    uniqueKeys: string | string[],
    options: {
      chunkSize?: number;
      database?: string; // Optional database override
    } = {}
  ): Promise<{ insertedCount: number; updatedCount: number; errors: unknown[] }> {
    if (!this.client) {
      throw new Error('MongoDB client not connected');
    }

    if (documents.length === 0) {
      return { insertedCount: 0, updatedCount: 0, errors: [] };
    }

    // Normalize uniqueKeys to array
    const keyFields = Array.isArray(uniqueKeys) ? uniqueKeys : [uniqueKeys];

    if (keyFields.length === 0) {
      throw new Error('At least one unique key must be provided');
    }

    const { chunkSize = 10000, database } = options;
    const db = this.getDatabase(database);
    const collection = db.collection<T>(collectionName);
    const operationId = Math.random().toString(36).substring(7);
    const dbName = database || this.defaultDatabase;

    let totalInserted = 0;
    let totalUpdated = 0;
    const errors: unknown[] = [];

    this.logger.info(`Starting batch upsert operation [${operationId}]`, {
      database: dbName,
      collection: collectionName,
      totalDocuments: documents.length,
      uniqueKeys: keyFields,
      chunkSize,
    });

    // Process documents in chunks to avoid memory issues
    for (let i = 0; i < documents.length; i += chunkSize) {
      const chunk = documents.slice(i, i + chunkSize);

      try {
        const startTime = Date.now();

        // Prepare bulk operations
        const bulkOps = chunk.map(doc => {
          const now = new Date();
          const docWithTimestamps = {
            ...doc,
            created_at: doc.created_at || now,
            updated_at: now,
          };

          // Create filter using multiple unique keys
          const filter: Record<string, unknown> = {};
          keyFields.forEach(key => {
            const value = (doc as Record<string, unknown>)[key];
            if (value === undefined || value === null) {
              throw new Error(`Document missing required unique key: ${key}`);
            }
            filter[key] = value;
          });

          // Remove created_at from $set to avoid conflict with $setOnInsert
          const { created_at, ...updateFields } = docWithTimestamps;

          return {
            updateOne: {
              filter,
              update: {
                $set: updateFields,
                $setOnInsert: { created_at },
              },
              upsert: true,
            },
          };
        });

        // Execute bulk operation with type assertion to handle complex MongoDB types
        const result = await collection.bulkWrite(bulkOps as never, { ordered: false });

        const executionTime = Date.now() - startTime;
        const inserted = result.upsertedCount;
        const updated = result.modifiedCount;

        totalInserted += inserted;
        totalUpdated += updated;

        this.logger.debug(`Batch upsert chunk processed [${operationId}]`, {
          chunkNumber: Math.floor(i / chunkSize) + 1,
          chunkSize: chunk.length,
          inserted,
          updated,
          executionTime,
          database: dbName,
          collection: collectionName,
        });
      } catch (error) {
        this.logger.error(`Batch upsert failed on chunk [${operationId}]`, {
          error,
          database: dbName,
          collection: collectionName,
          chunkNumber: Math.floor(i / chunkSize) + 1,
          chunkStart: i,
          chunkSize: chunk.length,
          uniqueKeys: keyFields,
        });
        errors.push(error);
      }
    }

    this.logger.info(`Batch upsert completed [${operationId}]`, {
      database: dbName,
      collection: collectionName,
      totalRecords: documents.length,
      inserted: totalInserted,
      updated: totalUpdated,
      errors: errors.length,
      uniqueKeys: keyFields,
    });

    return { insertedCount: totalInserted, updatedCount: totalUpdated, errors };
  }

  /**
   * Get a typed collection
   */
  getCollection<T extends DocumentBase>(name: string, database?: string): Collection<T> {
    const db = this.getDatabase(database);
    return db.collection<T>(name);
  }

  /**
   * Simple insert operation
   */
  async insertOne<T extends DocumentBase>(
    collectionName: string,
    document: Omit<T, '_id' | 'created_at' | 'updated_at'> &
      Partial<Pick<T, 'created_at' | 'updated_at'>>,
    database?: string
  ): Promise<T> {
    const collection = this.getCollection<T>(collectionName, database);

    const now = new Date();
    const docWithTimestamps = {
      ...document,
      created_at: document.created_at || now,
      updated_at: now,
    } as T;

    const result = await collection.insertOne(docWithTimestamps as OptionalUnlessRequiredId<T>);
    return { ...docWithTimestamps, _id: result.insertedId } as T;
  }

  /**
   * Check if client is connected
   */
  get connected(): boolean {
    return this.isConnected && !!this.client;
  }

  /**
   * Get the default database instance
   */
  get database(): Db | null {
    return this.db;
  }

  /**
   * Convenience methods for common databases
   */

  // Stock database operations
  async batchUpsertStock<T extends DocumentBase>(
    collectionName: string,
    documents: Array<
      Omit<T, '_id' | 'created_at' | 'updated_at'> & Partial<Pick<T, 'created_at' | 'updated_at'>>
    >,
    uniqueKeys: string | string[],
    options: { chunkSize?: number } = {}
  ) {
    return this.batchUpsert(collectionName, documents, uniqueKeys, {
      ...options,
      database: 'stock',
    });
  }

  // Trading documents database operations
  async batchUpsertTrading<T extends DocumentBase>(
    collectionName: string,
    documents: Array<
      Omit<T, '_id' | 'created_at' | 'updated_at'> & Partial<Pick<T, 'created_at' | 'updated_at'>>
    >,
    uniqueKeys: string | string[],
    options: { chunkSize?: number } = {}
  ) {
    return this.batchUpsert(collectionName, documents, uniqueKeys, {
      ...options,
      database: 'trading_documents',
    });
  }

  // Analytics database operations
  async batchUpsertAnalytics<T extends DocumentBase>(
    collectionName: string,
    documents: Array<
      Omit<T, '_id' | 'created_at' | 'updated_at'> & Partial<Pick<T, 'created_at' | 'updated_at'>>
    >,
    uniqueKeys: string | string[],
    options: { chunkSize?: number } = {}
  ) {
    return this.batchUpsert(collectionName, documents, uniqueKeys, {
      ...options,
      database: 'analytics',
    });
  }

  private buildConnectionUri(): string {
    if (this.config.uri) {
      return this.config.uri;
    }

    const { host, port, username, password, database, authSource } = this.config;

    // Build URI components
    const auth = username && password ? `${username}:${password}@` : '';
    const authParam = authSource && username ? `?authSource=${authSource}` : '';

    return `mongodb://${auth}${host}:${port}/${database}${authParam}`;
  }
}