const Database = require('better-sqlite3');
const path = require('path');
const fs = require('fs');

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

  const db = new Database(dbPath);
  
  // Enable foreign keys
  db.pragma('foreign_keys = ON');
  
  console.log('Initializing database schema...');

  // Dogs table - NO sire/dam columns, only litter_id
  db.exec(`
    CREATE TABLE IF NOT EXISTS dogs (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      name TEXT NOT NULL,
      registration_number TEXT UNIQUE,
      breed TEXT NOT NULL,
      sex TEXT NOT NULL CHECK(sex IN ('male', 'female')),
      birth_date DATE,
      color TEXT,
      microchip TEXT,
      photo_urls TEXT, -- JSON array of photo URLs
      notes TEXT,
      litter_id INTEGER,
      is_active INTEGER DEFAULT 1,
      created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
      updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
      FOREIGN KEY (litter_id) REFERENCES litters(id) ON DELETE SET NULL
    )
  `);

  // Create unique index for microchip that allows NULL values
  db.exec(`
    CREATE UNIQUE INDEX IF NOT EXISTS idx_dogs_microchip 
    ON dogs(microchip) 
    WHERE microchip IS NOT NULL
  `);

  // Parents table - Stores sire/dam relationships
  db.exec(`
    CREATE TABLE IF NOT EXISTS parents (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      dog_id INTEGER NOT NULL,
      parent_id INTEGER NOT NULL,
      parent_type TEXT NOT NULL CHECK(parent_type IN ('sire', 'dam')),
      FOREIGN KEY (dog_id) REFERENCES dogs(id) ON DELETE CASCADE,
      FOREIGN KEY (parent_id) REFERENCES dogs(id) ON DELETE CASCADE,
      UNIQUE(dog_id, parent_type)
    )
  `);

  // Litters table - Breeding records
  db.exec(`
    CREATE TABLE IF NOT EXISTS litters (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      sire_id INTEGER NOT NULL,
      dam_id INTEGER NOT NULL,
      breeding_date DATE NOT NULL,
      whelping_date DATE,
      puppy_count INTEGER DEFAULT 0,
      notes TEXT,
      created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
      FOREIGN KEY (sire_id) REFERENCES dogs(id) ON DELETE CASCADE,
      FOREIGN KEY (dam_id) REFERENCES dogs(id) ON DELETE CASCADE
    )
  `);

  // Health records table
  db.exec(`
    CREATE TABLE IF NOT EXISTS health_records (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      dog_id INTEGER NOT NULL,
      record_type TEXT NOT NULL CHECK(record_type IN ('test', 'vaccination', 'exam', 'treatment', 'certification')),
      test_name TEXT,
      test_date DATE NOT NULL,
      result TEXT,
      document_url TEXT,
      notes TEXT,
      created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
      FOREIGN KEY (dog_id) REFERENCES dogs(id) ON DELETE CASCADE
    )
  `);

  // Heat cycles table
  db.exec(`
    CREATE TABLE IF NOT EXISTS heat_cycles (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      dog_id INTEGER NOT NULL,
      start_date DATE NOT NULL,
      end_date DATE,
      progesterone_peak_date DATE,
      breeding_date DATE,
      breeding_successful INTEGER DEFAULT 0,
      notes TEXT,
      created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
      FOREIGN KEY (dog_id) REFERENCES dogs(id) ON DELETE CASCADE
    )
  `);

  // Traits table - Genetic trait tracking
  db.exec(`
    CREATE TABLE IF NOT EXISTS traits (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      dog_id INTEGER NOT NULL,
      trait_category TEXT NOT NULL,
      trait_name TEXT NOT NULL,
      trait_value TEXT NOT NULL,
      inherited_from INTEGER,
      notes TEXT,
      FOREIGN KEY (dog_id) REFERENCES dogs(id) ON DELETE CASCADE,
      FOREIGN KEY (inherited_from) REFERENCES dogs(id) ON DELETE SET NULL
    )
  `);

  // Create indexes for performance
  db.exec(`
    CREATE INDEX IF NOT EXISTS idx_dogs_name ON dogs(name);
    CREATE INDEX IF NOT EXISTS idx_dogs_registration ON dogs(registration_number);
    CREATE INDEX IF NOT EXISTS idx_dogs_litter ON dogs(litter_id);
    CREATE INDEX IF NOT EXISTS idx_parents_dog ON parents(dog_id);
    CREATE INDEX IF NOT EXISTS idx_parents_parent ON parents(parent_id);
    CREATE INDEX IF NOT EXISTS idx_litters_sire ON litters(sire_id);
    CREATE INDEX IF NOT EXISTS idx_litters_dam ON litters(dam_id);
    CREATE INDEX IF NOT EXISTS idx_health_dog ON health_records(dog_id);
    CREATE INDEX IF NOT EXISTS idx_heat_dog ON heat_cycles(dog_id);
    CREATE INDEX IF NOT EXISTS idx_traits_dog ON traits(dog_id);
  `);

  // Create trigger for updated_at
  db.exec(`
    CREATE TRIGGER IF NOT EXISTS update_dogs_timestamp 
    AFTER UPDATE ON dogs
    FOR EACH ROW
    BEGIN
      UPDATE dogs SET updated_at = CURRENT_TIMESTAMP WHERE id = NEW.id;
    END;
  `);

  console.log('✓ Database schema initialized successfully!');
  console.log('✓ Dogs table: NO sire/dam columns, uses parents table');
  console.log('✓ Parents table: Stores sire/dam relationships');
  console.log('✓ Litters table: Links puppies via litter_id');
  
  db.close();
  return true;
}

function getDatabase() {
  const dbPath = process.env.DB_PATH || path.join(__dirname, '../../data/breedr.db');
  const db = new Database(dbPath);
  db.pragma('foreign_keys = ON');
  return db;
}

module.exports = { initDatabase, getDatabase };

// Run initialization if called directly
if (require.main === module) {
  const dbPath = process.env.DB_PATH || path.join(__dirname, '../../data/breedr.db');
  console.log('\n==========================================');
  console.log('BREEDR Database Initialization');
  console.log('==========================================');
  console.log(`Database: ${dbPath}`);
  console.log('==========================================\n');
  initDatabase(dbPath);
  console.log('\n✓ Database ready!\n');
}