"""
Database Base Configuration
===========================
CTO-201: Async SQLAlchemy setup

Features:
- SQLAlchemy 2.0 async engine
- PostgreSQL (asyncpg) - 188 PostgreSQL
- Session dependency injection

統帥鐵律 2026-03-23:
- 絕對禁止 SQLite
- 所有 Episodic Memory 必須使用 PostgreSQL
"""

from collections.abc import AsyncGenerator
from contextlib import asynccontextmanager

from sqlalchemy import text
from sqlalchemy.ext.asyncio import (
    AsyncEngine,
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)
from sqlalchemy.orm import DeclarativeBase

from src.core.config import settings

# =============================================================================
# Base Model
# =============================================================================

class Base(DeclarativeBase):
    """SQLAlchemy declarative base"""
    pass


# =============================================================================
# Engine & Session Factory
# =============================================================================

_engine: AsyncEngine | None = None
_session_factory: async_sessionmaker[AsyncSession] | None = None


def get_engine() -> AsyncEngine:
    """
    Get or create async engine

    統帥鐵律 2026-03-23:
    - 使用 DATABASE_URL (PostgreSQL)
    - 絕對禁止 SQLite
    """
    global _engine
    if _engine is None:
        database_url = settings.DATABASE_URL

        # 統帥鐵律: 禁止 SQLite (AWOOOI 憲法)
        # 🔴 違反此規則必須立即報錯，禁止 fallback
        if "sqlite" in database_url.lower():
            import structlog
            logger = structlog.get_logger(__name__)
            logger.error("sqlite_forbidden", url=database_url)
            raise ValueError(
                "SQLite is FORBIDDEN by AWOOOI Constitution. "
                "Set DATABASE_URL to PostgreSQL: postgresql+asyncpg://user:pass@host:5432/db"
            )

        _engine = create_async_engine(
            database_url,
            echo=settings.DEBUG,
            pool_size=10,
            max_overflow=20,
            pool_pre_ping=True,
        )
    return _engine


def get_session_factory() -> async_sessionmaker[AsyncSession]:
    """Get or create session factory"""
    global _session_factory
    if _session_factory is None:
        _session_factory = async_sessionmaker(
            bind=get_engine(),
            class_=AsyncSession,
            expire_on_commit=False,
            autoflush=False,
        )
    return _session_factory


# =============================================================================
# Dependency Injection
# =============================================================================

async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """
    FastAPI dependency for database session

    Usage:
        @router.get("/items")
        async def get_items(db: AsyncSession = Depends(get_db)):
            ...
    """
    factory = get_session_factory()
    async with factory() as session:
        try:
            from src.core.context import get_current_project_id

            # AwoooP Phase 2.3 (2026-05-04 ogt): SET LOCAL app.project_id 讓 RLS Policy 生效
            # 預設 'awoooi'，多租戶路由將透過 contextvar 注入實際 project_id
            await session.execute(
                text("SELECT set_config('app.project_id', :pid, TRUE)"),
                {"pid": get_current_project_id()},
            )
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise


@asynccontextmanager
async def get_db_context(project_id: str | None = None) -> AsyncGenerator[AsyncSession, None]:
    """
    Context manager for database session (non-FastAPI usage)

    AwoooP Phase 2.3/2.4: 優先序 — 明確參數 > contextvar > "awoooi"
    - Phase 2.3: 啟用 RLS tenant isolation（SET LOCAL app.project_id）
    - Phase 2.4: 從 asyncio contextvar 讀取 background loop 的 project_id

    Usage:
        async with get_db_context() as db:               # 繼承 contextvar 或預設 awoooi
            ...
        async with get_db_context("other-tenant") as db:  # 明確指定 tenant
            ...
    """
    from src.core.context import get_current_project_id
    effective_pid = project_id if project_id is not None else get_current_project_id()

    factory = get_session_factory()
    async with factory() as session:
        try:
            await session.execute(
                text("SELECT set_config('app.project_id', :pid, TRUE)"),
                {"pid": effective_pid},
            )
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise


# =============================================================================
# Initialization
# =============================================================================

_DB_BOOTSTRAP_LOCK_NAME = "awoooi:init_db:ddl"


async def init_db() -> None:
    """
    Initialize database tables

    Call this at application startup.
    """
    engine = get_engine()

    async with engine.connect() as lock_conn:
        # 2026-05-24 ogt + Codex: 兩個 API replica 同時啟動時，PostgreSQL 會在
        # ALTER TABLE ... IF NOT EXISTS 上互相等待並 deadlock。整段 bootstrap
        # DDL 必須序列化，避免 rollout 因一個 pod CrashLoop 變成 1/2 ready。
        await lock_conn.execute(
            text("SELECT pg_advisory_lock(hashtext(:lock_name))"),
            {"lock_name": _DB_BOOTSTRAP_LOCK_NAME},
        )
        try:
            await _run_init_db_ddl(engine)
        finally:
            await lock_conn.execute(
                text("SELECT pg_advisory_unlock(hashtext(:lock_name))"),
                {"lock_name": _DB_BOOTSTRAP_LOCK_NAME},
            )


async def _run_init_db_ddl(engine: AsyncEngine) -> None:
    """
    Run idempotent DB bootstrap DDL while caller holds the bootstrap advisory lock.
    """

    # 2026-04-15 ogt: 多 replica 並行啟動競爭修復
    # 問題：單一大 transaction 裡兩個 pod 同時建 table → 其中一個 CREATE INDEX 失敗
    #       PostgreSQL 中 transaction 內任何錯誤導致整個 transaction ROLLBACK
    #       → table + index 全消失 → 下次重啟同樣問題 → 無限 CrashLoop
    # 修法：每個 table 獨立 transaction；先 DROP INDEX IF EXISTS 清殘留孤兒 index；
    #       捕捉 "already exists" 讓並行 pod 優雅跳過
    async with engine.connect() as probe_conn:
        existing = set(await probe_conn.run_sync(
            lambda c: __import__('sqlalchemy', fromlist=['inspect']).inspect(c).get_table_names()
        ))

    for table in Base.metadata.sorted_tables:
        if table.name not in existing:
            try:
                async with engine.begin() as conn:
                    # 先清殘留孤兒 index（前次 CrashLoop 留下的部分狀態）
                    for index in table.indexes:
                        await conn.execute(text(f'DROP INDEX IF EXISTS "{index.name}"'))
                    await conn.run_sync(table.create)
            except Exception as exc:
                if "already exists" in str(exc).lower():
                    pass  # 並行 pod 已建好，忽略
                else:
                    raise

    async with engine.begin() as conn:
        # 2026-04-02 Claude Code: 確保 risklevel enum 包含 'high' 值
        # Phase 23 新增，避免舊 DB 缺少此值導致 InvalidTextRepresentation
        await conn.execute(
            text("""
            DO $$
            BEGIN
                IF NOT EXISTS (
                    SELECT 1 FROM pg_enum
                    WHERE enumtypid = 'risklevel'::regtype
                      AND enumlabel = 'high'
                ) THEN
                    ALTER TYPE risklevel ADD VALUE 'high';
                END IF;
            END
            $$;
            """)
        )

        # 2026-04-09 Claude Sonnet 4.6: Sprint 5R C1 修復 — 批准執行閉環 Telegram 訊息持久化欄位
        # create_all 不做 ALTER，需手動補欄位
        await conn.execute(
            text("""
            ALTER TABLE approval_records
                ADD COLUMN IF NOT EXISTS telegram_message_id INTEGER,
                ADD COLUMN IF NOT EXISTS telegram_chat_id INTEGER;
            """)
        )

        # 2026-04-15 ogt + Claude Sonnet 4.6（亞太）: Phase 3.5 Playbook PostgreSQL 持久化
        # ADR-085: AI 學習成果不可存 Cache — trust_score、EWMA 必須永久保存
        # playbooks 表已存在（15 筆舊資料），補加新欄位
        await conn.execute(
            text("""
            ALTER TABLE playbooks
                ADD COLUMN IF NOT EXISTS trust_score FLOAT NOT NULL DEFAULT 0.3,
                ADD COLUMN IF NOT EXISTS requires_approval_level VARCHAR(20) NOT NULL DEFAULT 'auto',
                ADD COLUMN IF NOT EXISTS stateful_targets JSONB NOT NULL DEFAULT '[]',
                ADD COLUMN IF NOT EXISTS requires_pre_backup BOOLEAN NOT NULL DEFAULT FALSE,
                ADD COLUMN IF NOT EXISTS version INTEGER NOT NULL DEFAULT 1,
                ADD COLUMN IF NOT EXISTS parent_playbook_id VARCHAR(36),
                ADD COLUMN IF NOT EXISTS supersedes_playbook_id VARCHAR(36),
                ADD COLUMN IF NOT EXISTS version_reason TEXT;
            """)
        )
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS ix_playbook_lineage "
            "ON playbooks(parent_playbook_id, version);"
        ))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS ix_playbook_supersedes "
            "ON playbooks(supersedes_playbook_id) WHERE supersedes_playbook_id IS NOT NULL;"
        ))
        await conn.execute(text(
            "UPDATE playbooks SET parent_playbook_id = playbook_id WHERE parent_playbook_id IS NULL;"
        ))

        # 2026-04-15 ogt + Claude Sonnet 4.6（亞太）: Phase 4 8D 感官升級
        # ADR-084: EvidenceSnapshot 加入 Phase 4 動態異常上下文（anomaly_context）
        await conn.execute(
            text("""
            ALTER TABLE incident_evidence
                ADD COLUMN IF NOT EXISTS anomaly_context JSONB;
            """)
        )

        # W2 PR-V1: SelfHealingValidator 補欄 (2026-04-28 ogt + Claude Sonnet 4.6)
        # incident_evidence 加 self_healing_score + self_healing_detail
        # create_all 不做 ALTER，防禦性補加（prod 已存在的表不會自動加欄）
        await conn.execute(
            text("""
            ALTER TABLE incident_evidence
                ADD COLUMN IF NOT EXISTS self_healing_score FLOAT,
                ADD COLUMN IF NOT EXISTS self_healing_detail JSONB;
            """)
        )

        # 2026-04-29 ogt + Claude Opus 4.7: PR-K1 防禦性 ALTER (db-expert finding)
        # P1.6 (2026-04-24) ORM 已加 timeline_events.incident_id，但 prod 若在 P1.6 前
        # 已建表，create_all 跳過已存在的表 → ALTER 不會跑 → ORM 寫入 SELECT 找不到欄位
        # 補防禦性 IF NOT EXISTS（已有 column 為 no-op，安全）
        await conn.execute(
            text("""
            ALTER TABLE timeline_events
                ADD COLUMN IF NOT EXISTS incident_id VARCHAR(64);
            """)
        )

        # 2026-04-29 ogt + Claude Opus 4.7: M4 KMWriter 反查鏈 + 冪等補欄
        # CD #1115-1117 全 failure 根因：commit c22e5f33 加 ORM 欄位但無對應 ALTER
        #   錯誤：column "related_approval_id" of relation "knowledge_entries" does not exist
        # 補防禦性 ALTER（同 timeline_events 模式）+ 對應 index
        await conn.execute(
            text("""
            ALTER TABLE knowledge_entries
                ADD COLUMN IF NOT EXISTS related_approval_id VARCHAR(64),
                ADD COLUMN IF NOT EXISTS path_type VARCHAR(50);
            """)
        )
        # M3 冪等 unique index (incident_id + path_type)
        await conn.execute(text(
            "CREATE UNIQUE INDEX IF NOT EXISTS uix_knowledge_incident_path "
            "ON knowledge_entries(related_incident_id, path_type) "
            "WHERE related_incident_id IS NOT NULL AND path_type IS NOT NULL;"
        ))
        # M4 反查鏈 partial index（approval_id → KM 反查）
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS ix_knowledge_related_approval "
            "ON knowledge_entries(related_approval_id) "
            "WHERE related_approval_id IS NOT NULL;"
        ))

        # W2 PR-L1 2026-04-28 ogt + Claude Sonnet 4.6: KM→Playbook 互饋回路（飛輪 C3 修復）
        # PlaybookRecord 新增 review_required 欄位
        # 已存在表不會被 create_all 重建，必須手動 ALTER
        await conn.execute(
            text("""
            ALTER TABLE playbooks
                ADD COLUMN IF NOT EXISTS review_required BOOLEAN NOT NULL DEFAULT FALSE;
            """)
        )
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS ix_playbook_review_required "
            "ON playbooks(review_required) WHERE review_required = true;"
        ))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS ix_timeline_incident_id "
            "ON timeline_events(incident_id);"
        ))

        # AwoooP Phase 2.6 (2026-05-04 ogt): budget_ledger 建表（ADR-120 Token Budget Hard Kill）
        await conn.execute(text("""
            CREATE TABLE IF NOT EXISTS budget_ledger (
                id          UUID DEFAULT gen_random_uuid() PRIMARY KEY,
                project_id  VARCHAR(64)    NOT NULL DEFAULT 'awoooi',
                agent_id    VARCHAR(128),
                run_id      UUID,
                model       VARCHAR(64),
                provider    VARCHAR(32),
                prompt_tokens     INT,
                completion_tokens INT,
                cost_usd    NUMERIC(10, 4) NOT NULL DEFAULT 0.0000,
                recorded_at TIMESTAMPTZ    NOT NULL DEFAULT NOW()
            );
        """))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS idx_budget_ledger_project_date "
            "ON budget_ledger(project_id, recorded_at DESC);"
        ))

        # AwoooP Phase 2.3 (2026-05-04 ogt): 四表加 project_id（RLS 多租戶隔離）
        # 防禦性 ALTER — 已存在欄位為 no-op，安全。
        # Batch 1 RLS migration 執行後，app.project_id 由 get_db_context() 自動設置。
        await conn.execute(text(
            "ALTER TABLE incidents "
            "ADD COLUMN IF NOT EXISTS project_id VARCHAR(64) NOT NULL DEFAULT 'awoooi';"
        ))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS idx_incidents_project_id "
            "ON incidents (project_id);"
        ))
        await conn.execute(text(
            "ALTER TABLE knowledge_entries "
            "ADD COLUMN IF NOT EXISTS project_id VARCHAR(64) NOT NULL DEFAULT 'awoooi';"
        ))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS idx_knowledge_entries_project_id "
            "ON knowledge_entries (project_id);"
        ))
        await conn.execute(text(
            "ALTER TABLE playbooks "
            "ADD COLUMN IF NOT EXISTS project_id VARCHAR(64) NOT NULL DEFAULT 'awoooi';"
        ))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS idx_playbooks_project_id "
            "ON playbooks (project_id);"
        ))
        await conn.execute(text(
            "ALTER TABLE audit_logs "
            "ADD COLUMN IF NOT EXISTS project_id VARCHAR(64) NOT NULL DEFAULT 'awoooi';"
        ))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS idx_audit_logs_project_id "
            "ON audit_logs (project_id);"
        ))

        # 2026-04-15 ogt + Claude Sonnet 4.6（亞太）: Phase 6 自我治理閉環
        # ADR-087: ai_governance_events 不可變 Event Sourcing 表
        # asyncpg 不允許 prepared statement 內多條指令，必須分開 execute
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS ix_ai_governance_event_type "
            "ON ai_governance_events (event_type);"
        ))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS ix_ai_governance_triggered_at "
            "ON ai_governance_events (triggered_at);"
        ))
        await conn.execute(text(
            "CREATE INDEX IF NOT EXISTS ix_ai_governance_resolved "
            "ON ai_governance_events (resolved);"
        ))


async def close_db() -> None:
    """
    Close database connections

    Call this at application shutdown.
    """
    global _engine, _session_factory
    if _engine is not None:
        await _engine.dispose()
        _engine = None
        _session_factory = None