from flask import Blueprint, Response, current_app, jsonify, redirect, request
from sqlalchemy import select
from sqlalchemy.exc import IntegrityError

from l4d2web.auth import current_user, require_login
from l4d2web.db import session_scope
from l4d2web.models import Blueprint as BlueprintModel
from l4d2web.models import Job, Server
from l4d2web.services.security import validate_instance_name


bp = Blueprint("server", __name__)


def _allocate_next_port(db) -> int | None:
    start = int(current_app.config["PORT_RANGE_START"])
    end = int(current_app.config["PORT_RANGE_END"])
    used = set(
        db.scalars(
            select(Server.port).where(Server.port >= start, Server.port <= end)
        ).all()
    )
    for port in range(start, end + 1):
        if port not in used:
            return port
    return None


def _resolve_port(payload, db) -> tuple[int | None, Response | None]:
    raw = payload.get("port")
    if raw is None or (isinstance(raw, str) and raw.strip() == ""):
        port = _allocate_next_port(db)
        if port is None:
            return None, Response("no free port available", status=409)
        return port, None
    try:
        port = int(raw)
    except (TypeError, ValueError):
        return None, Response("invalid port", status=400)
    if not 1 <= port <= 65535:
        return None, Response("invalid port", status=400)
    return port, None


@bp.post("/servers")
@require_login
def create_server() -> Response:
    user = current_user()
    assert user is not None
    json_response = request.is_json
    payload = request.get_json(silent=True) if json_response else request.form

    try:
        name = validate_instance_name(str(payload["name"]))
    except (KeyError, TypeError, ValueError):
        return Response("invalid server name", status=400)

    with session_scope() as db:
        blueprint = db.scalar(
            select(BlueprintModel).where(
                BlueprintModel.id == int(payload["blueprint_id"]),
                BlueprintModel.user_id == user.id,
            )
        )
        if blueprint is None:
            return Response("blueprint not found", status=404)

        port, error = _resolve_port(payload, db)
        if error is not None:
            return error

        server = Server(
            user_id=user.id,
            blueprint_id=blueprint.id,
            name=name,
            port=port,
            desired_state="stopped",
            actual_state="unknown",
            last_error="",
        )
        db.add(server)

        try:
            db.flush()
        except IntegrityError:
            db.rollback()
            return Response("port already in use", status=409)

        server_id = server.id

    if json_response:
        return jsonify({"id": server_id}), 201
    return redirect(f"/servers/{server_id}")


@bp.patch("/servers/<int:server_id>")
@require_login
def update_server(server_id: int) -> Response:
    user = current_user()
    assert user is not None
    payload = request.get_json(silent=True) or {}

    with session_scope() as db:
        server = db.scalar(select(Server).where(Server.id == server_id, Server.user_id == user.id))
        if server is None:
            return Response(status=404)

        blueprint = db.scalar(
            select(BlueprintModel).where(
                BlueprintModel.id == int(payload["blueprint_id"]),
                BlueprintModel.user_id == user.id,
            )
        )
        if blueprint is None:
            return Response("blueprint not found", status=404)

        server.blueprint_id = blueprint.id

    return jsonify({"id": server_id}), 200


LIFECYCLE_OPERATIONS = {"initialize", "start", "stop", "delete"}


@bp.post("/servers/<int:server_id>/<operation>")
@require_login
def enqueue_server_operation(server_id: int, operation: str) -> Response:
    user = current_user()
    assert user is not None
    if operation not in LIFECYCLE_OPERATIONS:
        return Response(status=404)

    with session_scope() as db:
        server = db.scalar(select(Server).where(Server.id == server_id, Server.user_id == user.id))
        if server is None:
            return Response(status=404)
        db.add(Job(user_id=user.id, server_id=server.id, operation=operation, state="queued"))
        if operation == "start":
            server.desired_state = "running"
        if operation in {"stop", "delete"}:
            server.desired_state = "stopped"

    if operation == "delete":
        return redirect("/servers")
    return redirect(f"/servers/{server_id}")