"""
自動數據庫遷移 - 添加修正追踪欄位
在應用啟動時執行
"""

import os
from psycopg import connect

def run_auto_migration():
    """自動遷移：添加修正追踪欄位"""
    
    try:
        conn = connect(
            host=os.getenv("DB_HOST"),
            port=int(os.getenv("DB_PORT")),
            dbname=os.getenv("DB_NAME"),
            user=os.getenv("DB_USER"),
            password=os.getenv("DB_PASSWORD"),
        )
        
        with conn.cursor() as cur:
            print("\n" + "=" * 80)
            print("【自動數據庫遷移】")
            print("=" * 80)
            
            # 1. 添加 is_latest 欄位
            print("\n【步驟 1】檢查 is_latest 欄位...")
            try:
                cur.execute("""
                    SELECT COUNT(*) 
                    FROM information_schema.columns 
                    WHERE table_name = 'journal_entries' AND column_name = 'is_latest'
                """)
                
                if cur.fetchone()[0] == 0:
                    # 欄位不存在，添加
                    try:
                        cur.execute("""
                            ALTER TABLE journal_entries 
                            ADD COLUMN is_latest BOOLEAN DEFAULT true
                        """)
                        conn.commit()
                        print("✓ 欄位 is_latest 已添加")
                    except Exception as e:
                        conn.rollback()
                        print(f"⚠️  無法添加 is_latest（可能由於權限）: {e}")
                else:
                    print("✓ 欄位 is_latest 已存在")
            except Exception as e:
                print(f"⚠️  檢查 is_latest 失敗: {e}")
            
            # 2. 添加 revision_count 欄位
            print("\n【步驟 2】檢查 revision_count 欄位...")
            try:
                cur.execute("""
                    SELECT COUNT(*) 
                    FROM information_schema.columns 
                    WHERE table_name = 'journal_entries' AND column_name = 'revision_count'
                """)
                
                if cur.fetchone()[0] == 0:
                    try:
                        cur.execute("""
                            ALTER TABLE journal_entries 
                            ADD COLUMN revision_count INTEGER DEFAULT 1
                        """)
                        conn.commit()
                        print("✓ 欄位 revision_count 已添加")
                    except Exception as e:
                        conn.rollback()
                        print(f"⚠️  無法添加 revision_count（可能由於權限）: {e}")
                else:
                    print("✓ 欄位 revision_count 已存在")
            except Exception as e:
                print(f"⚠️  檢查 revision_count 失敗: {e}")
            
            # 3. 添加 original_entry_id 欄位
            print("\n【步驟 3】檢查 original_entry_id 欄位...")
            try:
                cur.execute("""
                    SELECT COUNT(*) 
                    FROM information_schema.columns 
                    WHERE table_name = 'journal_entries' AND column_name = 'original_entry_id'
                """)
                
                if cur.fetchone()[0] == 0:
                    try:
                        cur.execute("""
                            ALTER TABLE journal_entries 
                            ADD COLUMN original_entry_id INTEGER
                        """)
                        conn.commit()
                        print("✓ 欄位 original_entry_id 已添加")
                    except Exception as e:
                        conn.rollback()
                        print(f"⚠️  無法添加 original_entry_id（可能由於權限）: {e}")
                else:
                    print("✓ 欄位 original_entry_id 已存在")
            except Exception as e:
                print(f"⚠️  檢查 original_entry_id 失敗: {e}")
            
            # 4. 創建索引
            print("\n【步驟 4】創建索引...")
            try:
                cur.execute("""
                    CREATE INDEX IF NOT EXISTS idx_journal_entries_is_latest 
                    ON journal_entries(is_latest, entry_date)
                """)
                conn.commit()
                print("✓ 索引 idx_journal_entries_is_latest 已創建")
            except Exception as e:
                print(f"⚠️  無法創建索引: {e}")
            
            # 5. 驗證
            print("\n【步驟 5】驗證新欄位...")
            try:
                cur.execute("""
                    SELECT column_name, data_type
                    FROM information_schema.columns
                    WHERE table_name = 'journal_entries' 
                      AND column_name IN ('is_latest', 'revision_count', 'original_entry_id')
                    ORDER BY ordinal_position
                """)
                
                rows = cur.fetchall()
                if rows:
                    for row in rows:
                        col_name = row[0]
                        data_type = row[1]
                        print(f"  ✓ {col_name}: {data_type}")
                else:
                    print("  ℹ️  新欄位尚未存在（需要管理員執行遷移 SQL）")
            except Exception as e:
                print(f"⚠️  驗證失敗: {e}")
            
            print("\n" + "=" * 80)
            print("✓ 自動遷移檢查完成！")
            print("=" * 80 + "\n")
            
        conn.close()
        
    except Exception as e:
        print(f"\n❌ 無法連接到數據庫或執行遷移: {e}")
        print("\n提示：")
        print("1. 確認數據庫連接信息正確（DB_HOST, DB_PORT, DB_NAME, DB_USER, DB_PASSWORD）")
        print("2. 如果字段仍不存在，請使用管理員帳戶執行以下 SQL 命令:")
        print("""
        ALTER TABLE journal_entries ADD COLUMN IF NOT EXISTS is_latest BOOLEAN DEFAULT true;
        ALTER TABLE journal_entries ADD COLUMN IF NOT EXISTS revision_count INTEGER DEFAULT 1;
        ALTER TABLE journal_entries ADD COLUMN IF NOT EXISTS original_entry_id INTEGER;
        CREATE INDEX IF NOT EXISTS idx_journal_entries_is_latest ON journal_entries(is_latest, entry_date);
        """)


if __name__ == "__main__":
    run_auto_migration()