"""Action (Maßnahme) service — tenant-scoped CRUD, assignments, open actions."""

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 PRIORITIES, get_initiative
from services.plan_ist import validate_roadmap_item_in_initiative
from services.projects import project_is_leaf

ActionStatus = Literal[
    "open", "ready", "in_progress", "blocked", "review_required", "done", "discarded"
]

ACTION_STATUSES = frozenset(
    {"open", "ready", "in_progress", "blocked", "review_required", "done", "discarded"}
)
OPEN_ACTION_STATUSES = frozenset(
    {"open", "ready", "in_progress", "blocked", "review_required"}
)

_ACTION_COLUMNS = """
    id, tenant_id, initiative_id, project_id, roadmap_item_id, title, description,
    status, priority, due_at, created_at, updated_at
"""


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


def _validate_action_status(status: str) -> None:
    if status not in ACTION_STATUSES:
        raise ValueError(f"Ungültiger Action-Status: {status}")


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


def _load_assignments(*, tenant_id: str, action_ids: list[str]) -> dict[str, list[str]]:
    if not action_ids:
        return {}
    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                """
                SELECT action_id, actor_id
                FROM action_assignments
                WHERE tenant_id = %s AND action_id = ANY(%s::uuid[])
                ORDER BY created_at
                """,
                (tenant_id, action_ids),
            )
            result: dict[str, list[str]] = {aid: [] for aid in action_ids}
            for row in cur.fetchall():
                result[str(row["action_id"])].append(str(row["actor_id"]))
            return result
    finally:
        conn.close()


def _attach_assignments(
    actions: list[dict[str, Any]], *, tenant_id: str
) -> list[dict[str, Any]]:
    if not actions:
        return actions
    action_ids = [a["id"] for a in actions]
    assignments = _load_assignments(tenant_id=tenant_id, action_ids=action_ids)
    for action in actions:
        action["assigned_actor_ids"] = assignments.get(action["id"], [])
    return actions


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 _validate_project_in_initiative(
    *, tenant_id: str, initiative_id: str, project_id: Optional[str]
) -> None:
    if not project_id:
        return
    conn = get_connection()
    try:
        with conn.cursor() as cur:
            cur.execute(
                """
                SELECT 1 FROM projects
                WHERE id = %s AND tenant_id = %s AND initiative_id = %s
                """,
                (project_id, tenant_id, initiative_id),
            )
            if not cur.fetchone():
                raise ValueError("Projekt gehört nicht zum Vorhaben")
            if not project_is_leaf(tenant_id=tenant_id, project_id=project_id):
                raise ValueError(
                    "Arbeitspakete nur an Blatt-Projekten (ohne Unterprojekte)"
                )
    finally:
        conn.close()


def create_action(
    *,
    tenant_id: str,
    initiative_id: str,
    title: str,
    description: str = "",
    status: ActionStatus = "open",
    priority: str = "normal",
    due_at: Optional[Any] = None,
    project_id: Optional[str] = None,
    roadmap_item_id: Optional[str] = None,
    assigned_actor_ids: Optional[list[str]] = None,
    user_id: Optional[str] = None,
) -> dict[str, Any]:
    title = title.strip()
    if not title:
        raise ValueError("Titel ist erforderlich")
    _validate_action_status(status)
    _validate_priority(priority)
    if not get_initiative(tenant_id=tenant_id, initiative_id=initiative_id):
        raise ValueError("Initiative nicht gefunden")
    _validate_project_in_initiative(
        tenant_id=tenant_id, initiative_id=initiative_id, project_id=project_id
    )

    assigned_actor_ids = assigned_actor_ids or []
    for actor_id in assigned_actor_ids:
        if not _actor_in_tenant(tenant_id=tenant_id, actor_id=actor_id):
            raise ValueError(f"Actor {actor_id} gehört nicht zum Tenant")

    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            validate_roadmap_item_in_initiative(
                cur,
                tenant_id=tenant_id,
                initiative_id=initiative_id,
                roadmap_item_id=roadmap_item_id,
            )
            cur.execute(
                f"""
                INSERT INTO actions (
                    tenant_id, initiative_id, project_id, roadmap_item_id, title, description,
                    status, priority, due_at
                )
                VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s)
                RETURNING {_ACTION_COLUMNS}
                """,
                (
                    tenant_id,
                    initiative_id,
                    project_id,
                    roadmap_item_id,
                    title,
                    description,
                    status,
                    priority,
                    due_at,
                ),
            )
            row = _serialize_row(dict(cur.fetchone()))
            for actor_id in assigned_actor_ids:
                cur.execute(
                    """
                    INSERT INTO action_assignments (tenant_id, action_id, actor_id)
                    VALUES (%s, %s, %s)
                    """,
                    (tenant_id, row["id"], actor_id),
                )
        conn.commit()
    finally:
        conn.close()

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


def list_actions_for_initiative(
    *, tenant_id: str, initiative_id: str
) -> list[dict[str, Any]]:
    if not get_initiative(tenant_id=tenant_id, initiative_id=initiative_id):
        return []
    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                f"""
                SELECT {_ACTION_COLUMNS}
                FROM actions
                WHERE tenant_id = %s AND initiative_id = %s
                ORDER BY updated_at DESC, title
                """,
                (tenant_id, initiative_id),
            )
            actions = [_serialize_row(dict(row)) for row in cur.fetchall()]
    finally:
        conn.close()
    return _attach_assignments(actions, tenant_id=tenant_id)


def get_action(*, tenant_id: str, action_id: str) -> Optional[dict[str, Any]]:
    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                f"""
                SELECT {_ACTION_COLUMNS}
                FROM actions
                WHERE id = %s AND tenant_id = %s
                """,
                (action_id, tenant_id),
            )
            row = cur.fetchone()
            if not row:
                return None
            action = _serialize_row(dict(row))
    finally:
        conn.close()
    return _attach_assignments([action], tenant_id=tenant_id)[0]


def update_action(
    *,
    tenant_id: str,
    action_id: str,
    user_id: Optional[str] = None,
    title: Optional[str] = None,
    description: Optional[str] = None,
    status: Optional[ActionStatus] = None,
    priority: Optional[str] = None,
    due_at: Optional[Any] = None,
    clear_due_at: bool = False,
    project_id: Optional[str] = None,
    clear_project: bool = False,
    roadmap_item_id: Optional[str] = None,
    clear_roadmap_item: bool = False,
) -> Optional[dict[str, Any]]:
    existing = get_action(tenant_id=tenant_id, action_id=action_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 description is not None:
        updates.append("description = %s")
        params.append(description)
    if status is not None:
        _validate_action_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 clear_due_at:
        updates.append("due_at = NULL")
    elif due_at is not None:
        updates.append("due_at = %s")
        params.append(due_at)
    if clear_project:
        updates.append("project_id = NULL")
    elif project_id is not None:
        _validate_project_in_initiative(
            tenant_id=tenant_id,
            initiative_id=existing["initiative_id"],
            project_id=project_id,
        )
        updates.append("project_id = %s")
        params.append(project_id)
    if clear_roadmap_item:
        updates.append("roadmap_item_id = NULL")
    elif roadmap_item_id is not None:
        conn = get_connection()
        try:
            with conn.cursor() as cur:
                validate_roadmap_item_in_initiative(
                    cur,
                    tenant_id=tenant_id,
                    initiative_id=existing["initiative_id"],
                    roadmap_item_id=roadmap_item_id,
                )
        finally:
            conn.close()
        updates.append("roadmap_item_id = %s")
        params.append(roadmap_item_id)

    if not updates:
        return existing

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

    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                f"""
                UPDATE actions
                SET {", ".join(updates)}
                WHERE id = %s AND tenant_id = %s
                RETURNING {_ACTION_COLUMNS}
                """,
                params,
            )
            row = cur.fetchone()
            if not row:
                return None
        conn.commit()
    finally:
        conn.close()

    result = get_action(tenant_id=tenant_id, action_id=action_id)
    assert result is not None

    log_audit(
        "action.updated",
        user_id=user_id,
        tenant_id=tenant_id,
        details={"action_id": action_id, "fields": updates},
    )
    if status is not None and status != old_status:
        log_audit(
            "action.status_changed",
            user_id=user_id,
            tenant_id=tenant_id,
            details={
                "action_id": action_id,
                "from_status": old_status,
                "to_status": status,
            },
        )
    return result


def set_action_assignments(
    *,
    tenant_id: str,
    action_id: str,
    actor_ids: list[str],
    user_id: Optional[str] = None,
) -> Optional[dict[str, Any]]:
    existing = get_action(tenant_id=tenant_id, action_id=action_id)
    if not existing:
        return None

    unique_actor_ids = list(dict.fromkeys(actor_ids))
    for actor_id in unique_actor_ids:
        if not _actor_in_tenant(tenant_id=tenant_id, actor_id=actor_id):
            raise ValueError(f"Actor {actor_id} gehört nicht zum Tenant")

    conn = get_connection()
    try:
        with conn.cursor() as cur:
            cur.execute(
                "DELETE FROM action_assignments WHERE action_id = %s AND tenant_id = %s",
                (action_id, tenant_id),
            )
            for actor_id in unique_actor_ids:
                cur.execute(
                    """
                    INSERT INTO action_assignments (tenant_id, action_id, actor_id)
                    VALUES (%s, %s, %s)
                    """,
                    (tenant_id, action_id, actor_id),
                )
            cur.execute(
                "UPDATE actions SET updated_at = NOW() WHERE id = %s AND tenant_id = %s",
                (action_id, tenant_id),
            )
        conn.commit()
    finally:
        conn.close()

    log_audit(
        "action.assigned",
        user_id=user_id,
        tenant_id=tenant_id,
        details={
            "action_id": action_id,
            "actor_ids": unique_actor_ids,
            "previous_actor_ids": existing.get("assigned_actor_ids", []),
        },
    )
    return get_action(tenant_id=tenant_id, action_id=action_id)


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

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


def list_open_actions_for_actor(
    *, tenant_id: str, actor_id: str
) -> list[dict[str, Any]]:
    conn = get_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cur:
            cur.execute(
                """
                SELECT a.id, a.tenant_id, a.initiative_id, a.title, a.description,
                       a.status, a.priority, a.due_at, a.created_at, a.updated_at,
                       i.title AS initiative_title
                FROM actions a
                JOIN action_assignments aa ON aa.action_id = a.id AND aa.tenant_id = a.tenant_id
                JOIN initiatives i ON i.id = a.initiative_id AND i.tenant_id = a.tenant_id
                WHERE a.tenant_id = %s
                  AND aa.actor_id = %s
                  AND a.status = ANY(%s)
                ORDER BY
                    CASE a.priority
                        WHEN 'high' THEN 0
                        WHEN 'normal' THEN 1
                        WHEN 'low' THEN 2
                    END,
                    a.updated_at DESC
                """,
                (tenant_id, actor_id, list(OPEN_ACTION_STATUSES)),
            )
            actions = [_serialize_row(dict(row)) for row in cur.fetchall()]
    finally:
        conn.close()
    return _attach_assignments(actions, tenant_id=tenant_id)