"""Blocker service — tenant-scoped CRUD (AP0.8b)."""

from __future__ import annotations

from typing import Any, Literal, Optional

from psycopg2.extras import RealDictCursor

from db import get_connection
from services.audit import log_audit
from services.initiatives import get_initiative

BlockerStatus = Literal["open", "in_progress", "resolved", "accepted_risk", "dismissed"]

BLOCKER_STATUSES = frozenset(
    {"open", "in_progress", "resolved", "accepted_risk", "dismissed"}
)


def _serialize_row(row: dict[str, Any]) -> dict[str, Any]:
    result = dict(row)
    for key in ("id", "tenant_id", "initiative_id", "action_id", "reported_by_actor_id"):
        if result.get(key):
            result[key] = str(result[key])
    if result.get("created_at"):
        result["created_at"] = result["created_at"].isoformat()
    if result.get("updated_at"):
        result["updated_at"] = result["updated_at"].isoformat()
    return result


def _validate_status(status: str) -> None:
    if status not in BLOCKER_STATUSES:
        raise ValueError(f"Ungültiger Blocker-Status: {status}")


def _actor_in_tenant(*, tenant_id: str, actor_id: str) -> bool:
    conn = get_connection()
    try:
        with conn.cursor() as cur:
            cur.execute(
                "SELECT 1 FROM actors WHERE id = %s AND tenant_id = %s AND is_active = TRUE",
                (actor_id, tenant_id),
            )
            return cur.fetchone() is not None
    finally:
        conn.close()


def _action_in_initiative(*, tenant_id: str, initiative_id: str, action_id: str) -> bool:
    conn = get_connection()
    try:
        with conn.cursor() as cur:
            cur.execute(
                """
                SELECT 1 FROM actions
                WHERE id = %s AND tenant_id = %s AND initiative_id = %s
                """,
                (action_id, tenant_id, initiative_id),
            )
            return cur.fetchone() is not None
    finally:
        conn.close()


def create_blocker(
    *,
    tenant_id: str,
    initiative_id: str,
    title: str,
    description: str = "",
    status: BlockerStatus = "open",
    action_id: Optional[str] = None,
    reported_by_actor_id: Optional[str] = None,
    user_id: Optional[str] = None,
    set_action_blocked: bool = False,
) -> dict[str, Any]:
    title = title.strip()
    if not title:
        raise ValueError("Titel ist erforderlich")
    _validate_status(status)
    if not get_initiative(tenant_id=tenant_id, initiative_id=initiative_id):
        raise ValueError("Initiative nicht gefunden")
    if action_id and not _action_in_initiative(
        tenant_id=tenant_id, initiative_id=initiative_id, action_id=action_id
    ):
        raise ValueError("Maßnahme gehört nicht zum Vorhaben")
    if reported_by_actor_id and not _actor_in_tenant(
        tenant_id=tenant_id, actor_id=reported_by_actor_id
    ):
        raise ValueError("Reporter-Actor gehört nicht zum Tenant")

    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                """
                INSERT INTO blockers (
                    tenant_id, initiative_id, action_id, title, description,
                    status, reported_by_actor_id
                )
                VALUES (%s, %s, %s, %s, %s, %s, %s)
                RETURNING id, tenant_id, initiative_id, action_id, title, description,
                          status, reported_by_actor_id, created_at, updated_at
                """,
                (
                    tenant_id,
                    initiative_id,
                    action_id,
                    title,
                    description,
                    status,
                    reported_by_actor_id,
                ),
            )
            row = _serialize_row(dict(cur.fetchone()))
            if set_action_blocked and action_id:
                cur.execute(
                    """
                    UPDATE actions SET status = 'blocked', updated_at = NOW()
                    WHERE id = %s AND tenant_id = %s
                    """,
                    (action_id, tenant_id),
                )
        conn.commit()
    finally:
        conn.close()

    log_audit(
        "blocker.created",
        user_id=user_id,
        tenant_id=tenant_id,
        details={"blocker_id": row["id"], "initiative_id": initiative_id, "title": title},
    )
    return row


def list_blockers_for_initiative(*, tenant_id: str, initiative_id: str) -> list[dict[str, Any]]:
    if not get_initiative(tenant_id=tenant_id, initiative_id=initiative_id):
        raise ValueError("Initiative nicht gefunden")

    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                """
                SELECT id, tenant_id, initiative_id, action_id, title, description,
                       status, reported_by_actor_id, created_at, updated_at
                FROM blockers
                WHERE tenant_id = %s AND initiative_id = %s
                ORDER BY updated_at DESC, title
                """,
                (tenant_id, initiative_id),
            )
            return [_serialize_row(dict(r)) for r in cur.fetchall()]
    finally:
        conn.close()


def get_blocker(*, tenant_id: str, blocker_id: str) -> Optional[dict[str, Any]]:
    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                """
                SELECT id, tenant_id, initiative_id, action_id, title, description,
                       status, reported_by_actor_id, created_at, updated_at
                FROM blockers
                WHERE id = %s AND tenant_id = %s
                """,
                (blocker_id, tenant_id),
            )
            row = cur.fetchone()
            return _serialize_row(dict(row)) if row else None
    finally:
        conn.close()


def update_blocker(
    *,
    tenant_id: str,
    blocker_id: str,
    user_id: Optional[str] = None,
    title: Optional[str] = None,
    description: Optional[str] = None,
    status: Optional[BlockerStatus] = None,
    action_id: Optional[str] = None,
    clear_action_id: bool = False,
) -> Optional[dict[str, Any]]:
    existing = get_blocker(tenant_id=tenant_id, blocker_id=blocker_id)
    if not existing:
        return None

    old_status = existing["status"]
    updates: list[str] = []
    params: list[Any] = []

    if title is not None:
        title = title.strip()
        if not title:
            raise ValueError("Titel ist erforderlich")
        updates.append("title = %s")
        params.append(title)
    if description is not None:
        updates.append("description = %s")
        params.append(description)
    if status is not None:
        _validate_status(status)
        updates.append("status = %s")
        params.append(status)
    if clear_action_id:
        updates.append("action_id = NULL")
    elif action_id is not None:
        if not _action_in_initiative(
            tenant_id=tenant_id,
            initiative_id=existing["initiative_id"],
            action_id=action_id,
        ):
            raise ValueError("Maßnahme gehört nicht zum Vorhaben")
        updates.append("action_id = %s")
        params.append(action_id)

    if not updates:
        return existing

    updates.append("updated_at = NOW()")
    params.extend([blocker_id, tenant_id])

    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                f"""
                UPDATE blockers
                SET {", ".join(updates)}
                WHERE id = %s AND tenant_id = %s
                RETURNING id, tenant_id, initiative_id, action_id, title, description,
                          status, reported_by_actor_id, created_at, updated_at
                """,
                params,
            )
            row = cur.fetchone()
            if not row:
                return None
            result = _serialize_row(dict(row))
        conn.commit()
    finally:
        conn.close()

    log_audit(
        "blocker.updated",
        user_id=user_id,
        tenant_id=tenant_id,
        details={"blocker_id": blocker_id},
    )
    if status is not None and status != old_status:
        log_audit(
            "blocker.status_changed",
            user_id=user_id,
            tenant_id=tenant_id,
            details={
                "blocker_id": blocker_id,
                "from_status": old_status,
                "to_status": status,
            },
        )
        from services.operating_transitions import after_blocker_status_change

        after_blocker_status_change(
            tenant_id=tenant_id,
            blocker_id=blocker_id,
            action_id=result.get("action_id"),
            initiative_id=result.get("initiative_id"),
            old_status=old_status,
            new_status=status,
            user_id=user_id,
        )
    return result


def delete_blocker(
    *,
    tenant_id: str,
    blocker_id: str,
    user_id: Optional[str] = None,
) -> bool:
    conn = get_connection()
    try:
        with conn.cursor() as cur:
            cur.execute(
                "DELETE FROM blockers WHERE id = %s AND tenant_id = %s RETURNING id",
                (blocker_id, tenant_id),
            )
            deleted = cur.fetchone() is not None
        conn.commit()
    finally:
        conn.close()

    if deleted:
        log_audit(
            "blocker.deleted",
            user_id=user_id,
            tenant_id=tenant_id,
            details={"blocker_id": blocker_id},
        )
    return deleted