"""Initiative (Vorhaben) service — tenant-scoped CRUD."""

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

InitiativeStatus = Literal["active", "paused", "completed", "archived"]
Priority = Literal["low", "normal", "high"]

INITIATIVE_STATUSES = frozenset({"active", "paused", "completed", "archived"})
PRIORITIES = frozenset({"low", "normal", "high"})


def _serialize_row(row: dict[str, Any]) -> dict[str, Any]:
    result = dict(row)
    for key in ("id", "tenant_id", "owner_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_initiative_status(status: str) -> None:
    if status not in INITIATIVE_STATUSES:
        raise ValueError(f"Ungültiger Initiative-Status: {status}")


def _validate_priority(priority: str) -> None:
    if priority not in PRIORITIES:
        raise ValueError(f"Ungültige Priorität: {priority}")


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 create_initiative(
    *,
    tenant_id: str,
    title: str,
    owner_actor_id: str,
    goal: str = "",
    status: InitiativeStatus = "active",
    priority: Priority = "normal",
    user_id: Optional[str] = None,
) -> dict[str, Any]:
    title = title.strip()
    if not title:
        raise ValueError("Titel ist erforderlich")
    _validate_initiative_status(status)
    _validate_priority(priority)
    if not _actor_in_tenant(tenant_id=tenant_id, actor_id=owner_actor_id):
        raise ValueError("Owner-Actor gehört nicht zum Tenant")

    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                """
                INSERT INTO initiatives (
                    tenant_id, title, goal, status, priority, owner_actor_id
                )
                VALUES (%s, %s, %s, %s, %s, %s)
                RETURNING id, tenant_id, title, goal, status, priority,
                          owner_actor_id, created_at, updated_at
                """,
                (tenant_id, title, goal, status, priority, owner_actor_id),
            )
            row = _serialize_row(dict(cur.fetchone()))
        conn.commit()
    finally:
        conn.close()

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


def list_initiatives(*, tenant_id: str) -> list[dict[str, Any]]:
    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                """
                SELECT id, tenant_id, title, goal, status, priority,
                       owner_actor_id, created_at, updated_at
                FROM initiatives
                WHERE tenant_id = %s
                ORDER BY updated_at DESC, title
                """,
                (tenant_id,),
            )
            return [_serialize_row(dict(row)) for row in cur.fetchall()]
    finally:
        conn.close()


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


def update_initiative(
    *,
    tenant_id: str,
    initiative_id: str,
    user_id: Optional[str] = None,
    title: Optional[str] = None,
    goal: Optional[str] = None,
    status: Optional[InitiativeStatus] = None,
    priority: Optional[Priority] = None,
    owner_actor_id: Optional[str] = None,
) -> Optional[dict[str, Any]]:
    existing = get_initiative(tenant_id=tenant_id, initiative_id=initiative_id)
    if not existing:
        return None

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

    if title is not None:
        title = title.strip()
        if not title:
            raise ValueError("Titel ist erforderlich")
        updates.append("title = %s")
        params.append(title)
    if goal is not None:
        updates.append("goal = %s")
        params.append(goal)
    if status is not None:
        _validate_initiative_status(status)
        updates.append("status = %s")
        params.append(status)
    if priority is not None:
        _validate_priority(priority)
        updates.append("priority = %s")
        params.append(priority)
    if owner_actor_id is not None:
        if not _actor_in_tenant(tenant_id=tenant_id, actor_id=owner_actor_id):
            raise ValueError("Owner-Actor gehört nicht zum Tenant")
        updates.append("owner_actor_id = %s")
        params.append(owner_actor_id)

    if not updates:
        return existing

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

    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                f"""
                UPDATE initiatives
                SET {", ".join(updates)}
                WHERE id = %s AND tenant_id = %s
                RETURNING id, tenant_id, title, goal, status, priority,
                          owner_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(
        "initiative.updated",
        user_id=user_id,
        tenant_id=tenant_id,
        details={"initiative_id": initiative_id, "fields": updates},
    )
    if status is not None and status != old_status:
        log_audit(
            "initiative.status_changed",
            user_id=user_id,
            tenant_id=tenant_id,
            details={
                "initiative_id": initiative_id,
                "from_status": old_status,
                "to_status": status,
            },
        )
    return result


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

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