/**
 * DuckDB Client for querying Apache Iceberg tables
 *
 * Uses DuckDB's native Iceberg and Parquet support to query data
 * directly from S3/MinIO without needing catalog-only libraries.
 */

import duckdb from 'duckdb';
import type { FastifyBaseLogger } from 'fastify';
import { promisify } from 'util';

type Database = duckdb.Database;
type Connection = duckdb.Connection;
const { Database, Connection } = duckdb;

export interface DuckDBConfig {
  catalogUri: string;
  namespace: string;
  ohlcCatalogUri?: string;
  ohlcNamespace?: string;
  s3Endpoint?: string;
  s3AccessKey?: string;
  s3SecretKey?: string;
  conversationsBucket?: string;  // S3 bucket for conversation cold storage
}

/**
 * DuckDB Client with Iceberg support
 *
 * Provides SQL-based queries against Iceberg tables stored in S3/MinIO.
 */
export class DuckDBClient {
  private db: Database | null = null;
  private conn: Connection | null = null;
  private namespace: string;
  private ohlcNamespace: string;
  private catalogUri: string;
  private ohlcCatalogUri: string;
  private s3Config: {
    endpoint?: string;
    accessKey?: string;
    secretKey?: string;
  };
  private conversationsBucket?: string;
  private logger: FastifyBaseLogger;
  private initialized = false;

  constructor(config: DuckDBConfig, logger: FastifyBaseLogger) {
    this.logger = logger;
    this.namespace = config.namespace;
    this.catalogUri = config.catalogUri;
    this.ohlcCatalogUri = config.ohlcCatalogUri || config.catalogUri;
    this.ohlcNamespace = config.ohlcNamespace || 'trading';
    this.conversationsBucket = config.conversationsBucket;
    this.s3Config = {
      endpoint: config.s3Endpoint,
      accessKey: config.s3AccessKey,
      secretKey: config.s3SecretKey,
    };
  }

  /**
   * Initialize DuckDB connection and configure S3/Iceberg extensions
   */
  async initialize(): Promise<void> {
    if (this.initialized) {
      return;
    }

    try {
      this.db = new Database(':memory:');
      this.conn = this.db.connect();

      const all = promisify(this.conn.all.bind(this.conn));

      // Install and load required extensions
      await all('INSTALL httpfs;');
      await all('LOAD httpfs;');
      await all('INSTALL iceberg;');
      await all('LOAD iceberg;');

      // Configure S3 credentials if provided
      if (this.s3Config.endpoint && this.s3Config.accessKey && this.s3Config.secretKey) {
        const s3Url = new URL(this.s3Config.endpoint);
        const useSSL = s3Url.protocol === 'https:';

        await all(`SET s3_endpoint='${s3Url.hostname}:${s3Url.port || (useSSL ? 443 : 9000)}';`);
        await all(`SET s3_access_key_id='${this.s3Config.accessKey}';`);
        await all(`SET s3_secret_access_key='${this.s3Config.secretKey}';`);
        await all(`SET s3_use_ssl=${useSSL};`);
        await all(`SET s3_url_style='path';`);
        await all(`SET s3_region='us-east-1';`);
        await all(`SET s3_url_compatibility_mode=true;`);

        this.logger.info({
          endpoint: this.s3Config.endpoint,
          useSSL,
        }, 'Configured DuckDB S3 settings');
      }

      this.initialized = true;
      this.logger.info({
        catalogUri: this.catalogUri,
        namespace: this.namespace,
        ohlcCatalogUri: this.ohlcCatalogUri,
        ohlcNamespace: this.ohlcNamespace,
      }, 'DuckDB client initialized');
    } catch (error) {
      this.logger.error({ error }, 'Failed to initialize DuckDB');
      throw error;
    }
  }

  /**
   * Execute a SQL query and return all rows
   */
  private async query<T = any>(sql: string, params?: any[]): Promise<T[]> {
    if (!this.conn) {
      throw new Error('DuckDB connection not initialized');
    }

    try {
      const all = promisify(this.conn.all.bind(this.conn)) as (sql: string, ...params: any[]) => Promise<any[]>;
      const rows = params && params.length > 0 ? await all(sql, ...params) : await all(sql);
      return rows as T[];
    } catch (error) {
      this.logger.error({ error, sql, params }, 'DuckDB query failed');
      throw error;
    }
  }

  /**
   * Get the Iceberg table path from REST catalog
   */
  private async getTablePath(namespace: string, tableName: string, catalogUri: string): Promise<string | null> {
    try {
      const tableUrl = `${catalogUri}/v1/namespaces/${namespace}/tables/${tableName}`;

      this.logger.debug({ tableUrl }, 'Fetching Iceberg table metadata');

      const response = await fetch(tableUrl, {
        method: 'GET',
        headers: {
          'Content-Type': 'application/json',
        },
      });

      if (!response.ok) {
        if (response.status === 404) {
          this.logger.debug({ namespace, tableName }, 'Table not found in catalog');
          return null;
        }
        throw new Error(`Failed to fetch table metadata: ${response.status} ${response.statusText}`);
      }

      const metadata = await response.json() as any;

      // Extract metadata location (S3 path to metadata.json)
      const metadataLocation = metadata['metadata-location'] || metadata.location;

      if (!metadataLocation) {
        this.logger.warn({ metadata }, 'No metadata-location found in table response');
        return null;
      }

      this.logger.debug({ metadataLocation }, 'Found Iceberg table location');
      return metadataLocation;
    } catch (error: any) {
      this.logger.error({ error: error.message, namespace, tableName }, 'Failed to get table path');
      return null;
    }
  }

  /**
   * Query messages from gateway.conversations table
   */
  async queryMessages(
    userId: string,
    sessionId: string,
    options?: {
      startTime?: number;
      endTime?: number;
      limit?: number;
    }
  ): Promise<any[]> {
    await this.initialize();

    try {
      const tablePath = await this.getTablePath(
        this.namespace,
        'conversations',
        this.catalogUri
      );

      if (!tablePath) {
        // Fallback: scan Parquet files written directly to conversations bucket
        if (this.conversationsBucket) {
          this.logger.debug({ userId, sessionId }, 'REST catalog miss, scanning Parquet cold storage');
          const parquetPath = `s3://${this.conversationsBucket}/gateway/conversations/**/user_id=${userId}/${sessionId}.parquet`;
          const fallbackSql = `
            SELECT id, user_id, session_id, role, content, metadata, timestamp
            FROM read_parquet('${parquetPath}')
            ORDER BY timestamp ASC
            ${options?.limit ? `LIMIT ${options.limit}` : ''}
          `;
          try {
            return await this.query(fallbackSql);
          } catch {
            // File may not exist yet
          }
        }
        this.logger.warn('Conversations table not found and no cold storage configured');
        return [];
      }

      // Build SQL query with optional filters
      let sql = `
        SELECT
          id,
          user_id,
          session_id,
          role,
          content,
          metadata,
          timestamp
        FROM iceberg_scan('${tablePath}')
        WHERE user_id = ?
          AND session_id = ?
      `;

      const params: any[] = [userId, sessionId];

      if (options?.startTime) {
        sql += ' AND timestamp >= ?';
        params.push(options.startTime.toString());
      }

      if (options?.endTime) {
        sql += ' AND timestamp <= ?';
        params.push(options.endTime.toString());
      }

      sql += ' ORDER BY timestamp ASC';

      if (options?.limit) {
        sql += ' LIMIT ?';
        params.push(options.limit);
      }

      this.logger.debug({ userId, sessionId, options }, 'Querying conversation messages');

      const rows = await this.query(sql, params);

      this.logger.info({
        userId,
        sessionId,
        count: rows.length
      }, 'Loaded conversation messages from Iceberg');

      // Convert timestamp strings back to numbers
      return rows.map((row: any) => ({
        ...row,
        timestamp: Number(row.timestamp)
      }));
    } catch (error: any) {
      this.logger.error({
        error: error.message,
        userId,
        sessionId
      }, 'Failed to query conversation messages');
      return [];
    }
  }

  /**
   * Query checkpoint from gateway.checkpoints table
   */
  async queryCheckpoint(
    userId: string,
    sessionId: string,
    checkpointId?: string
  ): Promise<any | null> {
    await this.initialize();

    try {
      const tablePath = await this.getTablePath(
        this.namespace,
        'checkpoints',
        this.catalogUri
      );

      if (!tablePath) {
        this.logger.warn('Checkpoints table not found');
        return null;
      }

      let sql = `
        SELECT
          user_id,
          session_id,
          checkpoint_id,
          checkpoint_data,
          metadata,
          timestamp
        FROM iceberg_scan('${tablePath}')
        WHERE user_id = ?
          AND session_id = ?
      `;

      const params: any[] = [userId, sessionId];

      if (checkpointId) {
        sql += ' AND checkpoint_id = ?';
        params.push(checkpointId);
      }

      sql += ' ORDER BY timestamp DESC LIMIT 1';

      this.logger.debug({ userId, sessionId, checkpointId }, 'Querying checkpoint');

      const rows = await this.query(sql, params);

      if (rows.length === 0) {
        return null;
      }

      const row = rows[0];

      this.logger.info({
        userId,
        sessionId,
        checkpointId: row.checkpoint_id
      }, 'Loaded checkpoint from Iceberg');

      // Convert timestamp string back to number
      return {
        ...row,
        timestamp: Number(row.timestamp)
      };
    } catch (error: any) {
      this.logger.error({
        error: error.message,
        userId,
        sessionId,
        checkpointId
      }, 'Failed to query checkpoint');
      return null;
    }
  }

  /**
   * Query symbol metadata from trading.symbol_metadata table
   */
  async queryAllSymbols(): Promise<any[]> {
    await this.initialize();

    try {
      const tablePath = await this.getTablePath(
        this.ohlcNamespace,
        'symbol_metadata',
        this.ohlcCatalogUri
      );

      if (!tablePath) {
        this.logger.warn('Symbol metadata table not found');
        return [];
      }

      // Query the Iceberg table using DuckDB
      const sql = `SELECT * FROM iceberg_scan('${tablePath}')`;

      this.logger.debug({ sql }, 'Querying symbol metadata');

      const rows = await this.query(sql);

      this.logger.info({ count: rows.length }, 'Loaded symbol metadata from Iceberg');

      return rows;
    } catch (error: any) {
      this.logger.error({ error: error.message }, 'Failed to query symbol metadata');
      return [];
    }
  }

  /**
   * Query OHLC data from trading.ohlc table
   */
  async queryOHLC(
    ticker: string,
    period_seconds: number,
    start_time: bigint,  // nanoseconds
    end_time: bigint     // nanoseconds
  ): Promise<any[]> {
    await this.initialize();

    try {
      const tablePath = await this.getTablePath(
        this.ohlcNamespace,
        'ohlc',
        this.ohlcCatalogUri
      );

      if (!tablePath) {
        this.logger.warn('OHLC table not found');
        return [];
      }

      // Query the Iceberg table with filters
      const sql = `
        SELECT
          timestamp,
          ticker,
          period_seconds,
          open,
          high,
          low,
          close,
          volume
        FROM iceberg_scan('${tablePath}')
        WHERE ticker = ?
          AND period_seconds = ?
          AND timestamp >= ?
          AND timestamp < ?
        ORDER BY timestamp ASC
      `;

      const params = [
        ticker,
        period_seconds,
        start_time.toString(),
        end_time.toString()
      ];

      this.logger.debug({ ticker, period_seconds, start_time, end_time }, 'Querying OHLC data');

      const rows = await this.query(sql, params);

      this.logger.info({
        ticker,
        period_seconds,
        count: rows.length
      }, 'Loaded OHLC data from Iceberg');

      // Keep timestamp as bigint to preserve full microsecond precision.
      // Convert to seconds (divide first) only when producing TradingView bars.
      return rows.map((row: any) => ({
        ...row,
        timestamp: BigInt(row.timestamp)
      }));
    } catch (error: any) {
      this.logger.error({
        error: error.message,
        ticker,
        period_seconds
      }, 'Failed to query OHLC data');
      return [];
    }
  }

  /**
   * Check if OHLC data exists for the given parameters
   */
  async hasOHLCData(
    ticker: string,
    period_seconds: number,
    start_time: bigint,
    end_time: bigint
  ): Promise<boolean> {
    await this.initialize();

    try {
      const tablePath = await this.getTablePath(
        this.ohlcNamespace,
        'ohlc',
        this.ohlcCatalogUri
      );

      if (!tablePath) {
        return false;
      }

      const sql = `
        SELECT COUNT(*) as count
        FROM iceberg_scan('${tablePath}')
        WHERE ticker = ?
          AND period_seconds = ?
          AND timestamp >= ?
          AND timestamp < ?
      `;

      const params = [
        ticker,
        period_seconds,
        start_time.toString(),
        end_time.toString()
      ];

      const rows = await this.query<{ count: number }>(sql, params);
      return rows.length > 0 && rows[0].count > 0;
    } catch (error: any) {
      this.logger.error({ error: error.message }, 'Failed to check OHLC data existence');
      return false;
    }
  }

  /**
   * Find missing OHLC data ranges
   */
  async findMissingOHLCRanges(
    ticker: string,
    period_seconds: number,
    start_time: bigint,
    end_time: bigint
  ): Promise<Array<[bigint, bigint]>> {
    await this.initialize();

    try {
      const data = await this.queryOHLC(ticker, period_seconds, start_time, end_time);

      if (data.length === 0) {
        // All data is missing
        return [[start_time, end_time]];
      }

      // Check if we have continuous data
      // For now, simple check: if we have any data, assume complete
      // TODO: Implement proper gap detection by checking for missing periods
      const periodMicros = BigInt(period_seconds) * 1000000n;
      // end_time is exclusive, so expected count = (end - start) / period (no +1)
      const expectedBars = Number((end_time - start_time) / periodMicros);

      if (data.length < expectedBars * 0.95) { // Allow 5% tolerance
        this.logger.debug({
          ticker,
          expected: expectedBars,
          actual: data.length,
        }, 'Incomplete OHLC data detected');
        return [[start_time, end_time]]; // Request full range
      }

      // Data appears complete
      return [];
    } catch (error: any) {
      this.logger.error({ error: error.message }, 'Failed to find missing OHLC ranges');
      // Return full range on error (safe default)
      return [[start_time, end_time]];
    }
  }

  /**
   * Append a batch of conversation messages as a Parquet file in S3.
   * Called once per session at session end to avoid small-file fragmentation.
   */
  async appendMessages(
    userId: string,
    sessionId: string,
    messages: Array<{
      id: string;
      user_id: string;
      session_id: string;
      role: string;
      content: string;
      metadata: string;
      timestamp: number;
    }>
  ): Promise<void> {
    await this.initialize();

    if (!this.conversationsBucket || messages.length === 0) {
      return;
    }

    const now = new Date();
    const year = now.getUTCFullYear();
    const month = String(now.getUTCMonth() + 1).padStart(2, '0');
    const s3Path = `s3://${this.conversationsBucket}/gateway/conversations/year=${year}/month=${month}/user_id=${userId}/${sessionId}.parquet`;

    // Use a timestamp-based name to avoid cross-session collisions
    const tempTable = `msg_flush_${Date.now()}`;

    try {
      await this.query(`
        CREATE TEMP TABLE ${tempTable} (
          id VARCHAR,
          user_id VARCHAR,
          session_id VARCHAR,
          role VARCHAR,
          content VARCHAR,
          metadata VARCHAR,
          timestamp BIGINT
        )
      `);

      for (const msg of messages) {
        await this.query(
          `INSERT INTO ${tempTable} VALUES (?, ?, ?, ?, ?, ?, ?)`,
          [msg.id, msg.user_id, msg.session_id, msg.role, msg.content, msg.metadata, msg.timestamp]
        );
      }

      await this.query(`COPY ${tempTable} TO '${s3Path}' (FORMAT PARQUET)`);

      this.logger.info({ userId, sessionId, count: messages.length, s3Path }, 'Conversation flushed to Parquet');
    } finally {
      await this.query(`DROP TABLE IF EXISTS ${tempTable}`).catch(() => {});
    }
  }

  /**
   * Close the DuckDB connection
   */
  async close(): Promise<void> {
    if (this.conn) {
      const close = promisify(this.conn.close.bind(this.conn));
      await close();
      this.conn = null;
    }
    if (this.db) {
      const close = promisify(this.db.close.bind(this.db));
      await close();
      this.db = null;
    }
    this.initialized = false;
    this.logger.info('DuckDB client closed');
  }
}