"""Routes for Epic CRUD operations."""

from flask import request
from flask_jwt_extended import jwt_required
from flask_pydantic import validate

from app import db
from app.decorators import serialize_list_response, serialize_response
from app.models import Board, Card, Epic
from app.schemas import (CardResponse, EpicCreateRequest, EpicResponse,
                         EpicUpdateRequest)

from . import kanban_bp


@kanban_bp.route("/boards/<int:board_id>/epics", methods=["GET"])
@jwt_required()
@serialize_list_response(EpicResponse)
def get_board_epics(board_id):
    """Get all epics for a board."""
    board = db.session.get(Board, board_id)
    if not board:
        return {"error": "Board not found"}, 404

    epics = Epic.active().filter_by(board_id=board_id).all()
    return epics, 200


@kanban_bp.route("/boards/<int:board_id>/epics", methods=["POST"])
@jwt_required()
@validate(body=EpicCreateRequest)
@serialize_response(EpicResponse)
def create_epic(board_id, body: EpicCreateRequest):
    """Create a new epic for a board."""
    board = db.session.get(Board, board_id)
    if not board:
        return {"error": "Board not found"}, 404

    epic = Epic(
        board_id=board_id,
        name=body.name,
        description=body.description,
        content=body.content,
        color=body.color,
        closed=False,
        pos=body.pos,
        depth_limit=body.depth_limit,
        parent_epic_id=body.parent_epic_id,
        completed_list_id=body.completed_list_id,
        metrics={"card_count": 0, "completed_cards_count": 0},
    )

    db.session.add(epic)
    db.session.commit()

    return epic, 201


@kanban_bp.route("/epics/<int:epic_id>", methods=["GET"])
@jwt_required()
def get_epic(epic_id):
    """Get a specific epic with details."""
    epic = db.session.get(Epic, epic_id)
    if not epic:
        return {"error": "Epic not found"}, 404

    # Get cards for this epic
    cards = Card.active().filter_by(epic_id=epic_id).all()
    epic_dict = EpicResponse.model_validate(epic).model_dump()
    epic_dict["cards"] = [card.to_dict() for card in cards]

    return epic_dict, 200


def _update_epic_fields(epic: Epic, body: EpicUpdateRequest) -> None:
    """Update epic fields from request body."""
    if body.name is not None:
        epic.name = body.name
    if body.description is not None:
        epic.description = body.description
    if body.content is not None:
        epic.content = body.content
    if body.color is not None:
        epic.color = body.color
    if body.closed is not None:
        epic.closed = body.closed
    if body.pos is not None:
        epic.pos = body.pos
    if body.depth_limit is not None:
        epic.depth_limit = body.depth_limit
    if body.parent_epic_id is not None:
        epic.parent_epic_id = body.parent_epic_id
    if body.completed_list_id is not None:
        epic.completed_list_id = body.completed_list_id


@kanban_bp.route("/epics/<int:epic_id>", methods=["PUT"])
@jwt_required()
@validate(body=EpicUpdateRequest)
@serialize_response(EpicResponse)
def update_epic(epic_id, body: EpicUpdateRequest):
    """Update an epic."""
    epic = db.session.get(Epic, epic_id)
    if not epic:
        return {"error": "Epic not found"}, 404

    _update_epic_fields(epic, body)
    db.session.commit()

    return epic, 200


@kanban_bp.route("/epics/<int:epic_id>", methods=["DELETE"])
@jwt_required()
def delete_epic(epic_id):
    """Delete an epic."""
    epic = db.session.get(Epic, epic_id)
    if not epic:
        return {"error": "Epic not found"}, 404

    # Unlink all cards from this epic
    Card.active().filter_by(epic_id=epic_id).update({"epic_id": None})

    # Delete epic
    epic.soft_delete()
    db.session.commit()

    return {"message": "Epic deleted successfully"}, 200


@kanban_bp.route("/cards/<int:card_id>/epics", methods=["POST"])
@jwt_required()
@serialize_response(CardResponse)
def add_epic_to_card(card_id):
    """Link an epic to a card."""
    card = db.session.get(Card, card_id)
    if not card:
        return {"error": "Card not found"}, 404

    data = request.get_json()
    epic_id = data.get("epic_id")

    if not epic_id:
        return {"error": "epic_id is required"}, 400

    epic = db.session.get(Epic, epic_id)
    if not epic:
        return {"error": "Epic not found"}, 404

    card.epic_id = epic_id
    db.session.commit()

    return card, 200


@kanban_bp.route("/cards/<int:card_id>/epics/<int:epic_id>", methods=["DELETE"])
@jwt_required()
def remove_epic_from_card(card_id, epic_id):
    """Unlink an epic from a card."""
    card = db.session.get(Card, card_id)
    if not card:
        return {"error": "Card not found"}, 404

    if card.epic_id != epic_id:
        return {"error": "Card is not linked to this epic"}, 400

    card.epic_id = None
    db.session.commit()

    return {"message": "Epic unlinked from card successfully"}, 200