const sqlite3 = require('sqlite3').verbose();
const path = require('path');
const fs = require('fs');

const DB_PATH = path.join(__dirname, '..', 'data', 'homebase.db');

// Ensure data directory exists
const dataDir = path.dirname(DB_PATH);
if (!fs.existsSync(dataDir)) {
  fs.mkdirSync(dataDir, { recursive: true });
}

const db = new sqlite3.Database(DB_PATH, (err) => {
  if (err) {
    console.error('Database connection error:', err);
  } else {
    console.log('Connected to SQLite database at', DB_PATH);
  }
});

// Enable foreign keys
db.run('PRAGMA foreign_keys = ON');

/**
 * Initialize database schema
 */
async function initializeDatabase() {
  return new Promise((resolve, reject) => {
    db.serialize(() => {
      // Images table
      db.run(
        `CREATE TABLE IF NOT EXISTS images (
          id INTEGER PRIMARY KEY AUTOINCREMENT,
          filename TEXT NOT NULL UNIQUE,
          source_url TEXT NOT NULL,
          file_path TEXT NOT NULL,
          filesize INTEGER,
          file_hash TEXT NOT NULL,
          mime_type TEXT,
          fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
          created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
          updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
          is_corrupted BOOLEAN DEFAULT 0
        )`,
        (err) => {
          if (err) reject(err);
        }
      );

      // Tags table
      db.run(
        `CREATE TABLE IF NOT EXISTS tags (
          id INTEGER PRIMARY KEY AUTOINCREMENT,
          image_id INTEGER NOT NULL,
          tag TEXT NOT NULL,
          created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
          FOREIGN KEY (image_id) REFERENCES images(id) ON DELETE CASCADE,
          UNIQUE(image_id, tag)
        )`,
        (err) => {
          if (err) reject(err);
        }
      );

      // Create indexes for better query performance
      db.run('CREATE INDEX IF NOT EXISTS idx_images_source_url ON images(source_url)');
      db.run('CREATE INDEX IF NOT EXISTS idx_images_fetched_at ON images(fetched_at)');
      db.run('CREATE INDEX IF NOT EXISTS idx_images_file_hash ON images(file_hash)');
      db.run('CREATE INDEX IF NOT EXISTS idx_tags_image_id ON tags(image_id)');
      db.run('CREATE INDEX IF NOT EXISTS idx_tags_tag ON tags(tag)', (err) => {
        if (err) {
          reject(err);
        } else {
          console.log('Database initialized successfully');
          resolve();
        }
      });
    });
  });
}

/**
 * Insert a new image record
 */
function insertImage(imageData) {
  return new Promise((resolve, reject) => {
    const { filename, source_url, file_path, filesize, file_hash, mime_type } = imageData;
    
    db.run(
      `INSERT INTO images (filename, source_url, file_path, filesize, file_hash, mime_type)
       VALUES (?, ?, ?, ?, ?, ?)`,
      [filename, source_url, file_path, filesize, file_hash, mime_type],
      function(err) {
        if (err) {
          reject(err);
        } else {
          resolve({ id: this.lastID });
        }
      }
    );
  });
}

/**
 * Add tags to an image
 */
function addTags(imageId, tags) {
  return new Promise((resolve, reject) => {
    if (!Array.isArray(tags) || tags.length === 0) {
      resolve();
      return;
    }

    db.serialize(() => {
      const stmt = db.prepare(
        'INSERT OR IGNORE INTO tags (image_id, tag) VALUES (?, ?)'
      );

      let completed = 0;
      let hasError = false;

      tags.forEach((tag) => {
        stmt.run([imageId, tag], (err) => {
          if (err && !hasError) {
            hasError = true;
            stmt.finalize();
            reject(err);
          } else {
            completed++;
            if (completed === tags.length) {
              stmt.finalize((err) => {
                if (err) reject(err);
                else resolve();
              });
            }
          }
        });
      });
    });
  });
}

/**
 * Mark image as corrupted
 */
function markAsCorrupted(imageId) {
  return new Promise((resolve, reject) => {
    db.run(
      'UPDATE images SET is_corrupted = 1, updated_at = CURRENT_TIMESTAMP WHERE id = ?',
      [imageId],
      (err) => {
        if (err) reject(err);
        else resolve();
      }
    );
  });
}

/**
 * Get image by ID
 */
function getImage(imageId) {
  return new Promise((resolve, reject) => {
    db.get(
      'SELECT * FROM images WHERE id = ?',
      [imageId],
      (err, row) => {
        if (err) reject(err);
        else resolve(row);
      }
    );
  });
}

/**
 * Get all images with optional filtering
 */
function getImages(options = {}) {
  return new Promise((resolve, reject) => {
    const { tag, sourceUrl, limit = 100, offset = 0, sortBy = 'fetched_at', order = 'DESC' } = options;
    
    let query = 'SELECT DISTINCT i.* FROM images i';
    let params = [];

    if (tag) {
      query += ' INNER JOIN tags t ON i.id = t.image_id';
    }

    query += ' WHERE i.is_corrupted = 0';

    if (tag) {
      query += ' AND t.tag = ?';
      params.push(tag);
    }

    if (sourceUrl) {
      query += ' AND i.source_url = ?';
      params.push(sourceUrl);
    }

    query += ` ORDER BY i.${sortBy} ${order} LIMIT ? OFFSET ?`;
    params.push(limit, offset);

    db.all(query, params, (err, rows) => {
      if (err) reject(err);
      else resolve(rows || []);
    });
  });
}

/**
 * Get tags for an image
 */
function getImageTags(imageId) {
  return new Promise((resolve, reject) => {
    db.all(
      'SELECT tag FROM tags WHERE image_id = ? ORDER BY tag',
      [imageId],
      (err, rows) => {
        if (err) reject(err);
        else resolve((rows || []).map(r => r.tag));
      }
    );
  });
}

/**
 * Get all unique tags
 */
function getAllTags() {
  return new Promise((resolve, reject) => {
    db.all(
      'SELECT DISTINCT tag FROM tags ORDER BY tag',
      (err, rows) => {
        if (err) reject(err);
        else resolve((rows || []).map(r => r.tag));
      }
    );
  });
}

/**
 * Get image count
 */
function getImageCount(tag = null) {
  return new Promise((resolve, reject) => {
    let query = 'SELECT COUNT(*) as count FROM images WHERE is_corrupted = 0';
    let params = [];

    if (tag) {
      query = `SELECT COUNT(DISTINCT i.id) as count FROM images i 
               INNER JOIN tags t ON i.id = t.image_id 
               WHERE i.is_corrupted = 0 AND t.tag = ?`;
      params.push(tag);
    }

    db.get(query, params, (err, row) => {
      if (err) reject(err);
      else resolve(row?.count || 0);
    });
  });
}

/**
 * Delete image (soft delete - keeps file but marks for cleanup)
 */
function deleteImage(imageId) {
  return new Promise((resolve, reject) => {
    db.run(
      'DELETE FROM images WHERE id = ?',
      [imageId],
      (err) => {
        if (err) reject(err);
        else resolve();
      }
    );
  });
}

/**
 * Clean up old images (older than specified days)
 */
function cleanupOldImages(daysOld = 30) {
  return new Promise((resolve, reject) => {
    db.run(
      `DELETE FROM images WHERE fetched_at < datetime('now', '-' || ? || ' days')`,
      [daysOld],
      function(err) {
        if (err) reject(err);
        else resolve(this.changes);
      }
    );
  });
}

/**
 * Get images before a specific date (YYYY-MM-DD or YYYY-MM-DD HH:MM:SS)
 */
function getImagesBeforeDate(beforeDate) {
  return new Promise((resolve, reject) => {
    db.all(
      'SELECT id, file_path FROM images WHERE fetched_at < ? ORDER BY fetched_at ASC',
      [beforeDate],
      (err, rows) => {
        if (err) reject(err);
        else resolve(rows || []);
      }
    );
  });
}

/**
 * Delete images before a specific date (YYYY-MM-DD or YYYY-MM-DD HH:MM:SS)
 */
function deleteImagesBeforeDate(beforeDate) {
  return new Promise((resolve, reject) => {
    db.run(
      'DELETE FROM images WHERE fetched_at < ?',
      [beforeDate],
      function(err) {
        if (err) reject(err);
        else resolve(this.changes);
      }
    );
  });
}

/**
 * Get images by hash (detect duplicates)
 */
function getImagesByHash(hash) {
  return new Promise((resolve, reject) => {
    db.all(
      'SELECT * FROM images WHERE file_hash = ? AND is_corrupted = 0',
      [hash],
      (err, rows) => {
        if (err) reject(err);
        else resolve(rows || []);
      }
    );
  });
}

/**
 * Close database connection
 */
function closeDatabase() {
  return new Promise((resolve, reject) => {
    db.close((err) => {
      if (err) reject(err);
      else {
        console.log('Database connection closed');
        resolve();
      }
    });
  });
}

module.exports = {
  db,
  initializeDatabase,
  insertImage,
  addTags,
  markAsCorrupted,
  getImage,
  getImages,
  getImageTags,
  getAllTags,
  getImageCount,
  deleteImage,
  cleanupOldImages,
  getImagesBeforeDate,
  deleteImagesBeforeDate,
  getImagesByHash,
  closeDatabase
};