"""REST API handlers for game operations."""

import json
from datetime import datetime, timezone

import tornado.web

from game.factory import BoardFactory, DIRECTIONS
from models.category import Category
from models.game import Game, Word


class BaseAPIHandler(tornado.web.RequestHandler):
    """Base handler for JSON API endpoints."""

    def set_default_headers(self):
        self.set_header("Content-Type", "application/json")

    def get_session(self):
        Session = self.application.settings["session_factory"]
        return Session()

    def write_error(self, status_code, **kwargs):
        self.write(json.dumps({"error": self._reason}))


class CategoriesHandler(BaseAPIHandler):
    """``GET /api/categories`` -- list all word categories."""

    def get(self):
        session = self.get_session()
        try:
            categories = session.query(Category).all()
            self.write(json.dumps([{"id": c.id, "name": c.name} for c in categories]))
        finally:
            session.close()


class NewGameHandler(BaseAPIHandler):
    """``POST /api/game/new`` -- create a new game.

    Expects JSON body with ``category_id`` and optional ``board_size`` (8-20).
    """

    def post(self):
        session = self.get_session()
        try:
            data = json.loads(self.request.body)
            category_id = data["category_id"]
            board_size = data.get("board_size", 10)
            board_size = max(8, min(20, board_size))

            factory = BoardFactory(session)
            game, words = factory.create(
                category_id=category_id,
                board_size=board_size,
            )
            session.add(game)
            for w in words:
                session.add(w)
            session.commit()

            self.write(json.dumps(self._game_to_dict(game)))
        finally:
            session.close()

    def _game_to_dict(self, game):
        return {
            "id": game.id,
            "board_size": game.board_size,
            "category": game.category.name,
            "grid": game.grid,
            "words": [{"text": w.text, "found": w.found} for w in game.words],
            "started_at": game.started_at.isoformat() + "Z",
            "status": game.status,
            "completed_at": None,
        }


class GameStateHandler(BaseAPIHandler):
    """``GET /api/game/<id>`` -- retrieve current game state."""

    def get(self, game_id):
        session = self.get_session()
        try:
            game = session.query(Game).filter_by(id=game_id).first()
            if not game:
                self.set_status(404)
                self.write(json.dumps({"error": "Game not found"}))
                return
            self.write(
                json.dumps(
                    {
                        "id": game.id,
                        "board_size": game.board_size,
                        "category": game.category.name,
                        "grid": game.grid,
                        "words": [
                            {"text": w.text, "found": w.found} for w in game.words
                        ],
                        "started_at": game.started_at.isoformat() + "Z",
                        "status": game.status,
                        "completed_at": (
                            game.completed_at.isoformat() + "Z"
                            if game.completed_at
                            else None
                        ),
                    }
                )
            )
        finally:
            session.close()


class GuessHandler(BaseAPIHandler):
    """``POST /api/game/<id>/guess`` -- submit a word guess.

    Accepts either ``{"word": "..."}`` for text input or
    ``{"cells": [{"row": N, "col": N}, ...]}`` for click selection.
    """

    def post(self, game_id):
        session = self.get_session()
        try:
            game = session.query(Game).filter_by(id=game_id).first()
            if not game:
                self.set_status(404)
                self.write(json.dumps({"error": "Game not found"}))
                return

            data = json.loads(self.request.body)

            if "word" in data:
                result = self._handle_text_guess(session, game, data["word"])
            elif "cells" in data:
                result = self._handle_click_guess(session, game, data["cells"])
            else:
                self.set_status(400)
                self.write(json.dumps({"error": "Provide 'word' or 'cells'"}))
                return

            self.write(json.dumps(result))
        finally:
            session.close()

    def _handle_text_guess(self, session, game, guess_text):
        guess_text = guess_text.upper().strip()
        word = (
            session.query(Word)
            .filter_by(game_id=game.id, text=guess_text, found=False)
            .first()
        )
        if not word:
            return self._miss_response(game, session)

        return self._mark_found(session, game, word)

    def _handle_click_guess(self, session, game, cells):
        grid = game.grid
        try:
            letters = "".join(grid[c["row"]][c["col"]] for c in cells)
        except (IndexError, KeyError):
            return self._miss_response(game, session)

        word = (
            session.query(Word)
            .filter_by(game_id=game.id, text=letters, found=False)
            .first()
        )
        if not word:
            return self._miss_response(game, session)

        dr, dc = DIRECTIONS[word.direction]
        expected_cells = [
            {"row": word.start_row + i * dr, "col": word.start_col + i * dc}
            for i in range(len(word.text))
        ]
        if cells != expected_cells:
            return self._miss_response(game, session)

        return self._mark_found(session, game, word)

    def _mark_found(self, session, game, word):
        word.found = True
        word.found_at = datetime.now(timezone.utc)

        unfound = session.query(Word).filter_by(game_id=game.id, found=False).count()
        if unfound == 0:
            game.status = "completed"
            game.completed_at = datetime.now(timezone.utc)

        session.commit()

        dr, dc = DIRECTIONS[word.direction]
        cells = [
            {"row": word.start_row + i * dr, "col": word.start_col + i * dc}
            for i in range(len(word.text))
        ]

        return {
            "correct": True,
            "word": word.text,
            "cells": cells,
            "words": [{"text": w.text, "found": w.found} for w in game.words],
            "status": game.status,
            "completed_at": (
                game.completed_at.isoformat() + "Z" if game.completed_at else None
            ),
        }

    def _miss_response(self, game, session):
        return {
            "correct": False,
            "word": None,
            "cells": [],
            "words": [{"text": w.text, "found": w.found} for w in game.words],
            "status": game.status,
            "completed_at": None,
        }