#!/usr/bin/env python3
"""
Evaluation script for chess puzzle solving with Position2Move model.

This script evaluates how well a trained model can solve chess puzzles by:
1. Loading a trained model checkpoint
2. Testing it on puzzles from the Lichess puzzle database
3. Measuring accuracy for first move, full solution, and by rating/theme
4. Generating detailed reports

Usage:
    python src/chesstransformer/utils/evaluate_puzzles.py --model data/models/puzzle_training/run_001/best_model.pth

Options:
    --model: Path to model checkpoint (required)
    --puzzle-data: Path to puzzle .csv.zst file (default: data/lichess_db_puzzle.csv.zst)
    --num-puzzles: Number of puzzles to evaluate (default: 1000)
    --min-rating: Minimum puzzle rating (default: None)
    --max-rating: Maximum puzzle rating (default: None)
    --themes: Comma-separated puzzle themes to filter by (default: None)
    --output: Output JSON file for results (default: results/puzzle_eval_{timestamp}.json)
"""

from pathlib import Path
from datetime import datetime
import argparse
import json

import torch
import chess
from tqdm.auto import tqdm

from chesstransformer.datasets.puzzle_dataset import LichessPuzzleFullSolutionDataset
from chesstransformer.models.transformer.position2move import Position2MoveModel
from chesstransformer.models.tokenizer.position_tokenizer import PostionTokenizer
from chesstransformer.models.tokenizer.move_tokenizer import MoveTokenizer


class PuzzleEvaluator:
    """Evaluates a Position2Move model on chess puzzles."""

    def __init__(self, model, device="cpu"):
        self.model = model
        self.device = device
        self.model.to(device)
        self.model.eval()

        self.position_tokenizer = PostionTokenizer()
        self.move_tokenizer = MoveTokenizer()

    def predict_move(self, board: chess.Board, top_k=5):
        """
        Predict the best move for a given board position.

        Args:
            board: chess.Board object
            top_k: Return top-k predictions

        Returns:
            List of (move_uci, probability, is_legal) tuples
        """
        # Encode position
        position_tokens = self.position_tokenizer.encode(board)
        position_tensor = torch.tensor(position_tokens, dtype=torch.long).unsqueeze(0).to(self.device)
        is_white = torch.tensor([board.turn == chess.WHITE], dtype=torch.long).to(self.device)

        # Get predictions
        with torch.no_grad():
            logits = self.model(position_tensor, is_white)

            # Create legal moves mask
            legal_moves = [m.uci() for m in board.legal_moves]
            legal_move_indices = []
            for move_uci in legal_moves:
                try:
                    idx = self.move_tokenizer.encode(move_uci)
                    legal_move_indices.append(idx)
                except ValueError:
                    continue

            # Apply mask to logits (set illegal moves to -inf before softmax)
            mask = torch.full_like(logits, float("-inf"))
            if legal_move_indices:
                mask[0, legal_move_indices] = 0
                masked_logits = logits + mask

            probs = torch.softmax(masked_logits, dim=-1)

        # Get top-k predictions
        top_probs, top_indices = torch.topk(probs[0], k=top_k)

        predictions = []

        for prob, idx in zip(top_probs.cpu().numpy(), top_indices.cpu().numpy()):
            try:
                move_uci = self.move_tokenizer.decode(int(idx))
                is_legal = move_uci in legal_moves
                predictions.append((move_uci, float(prob), is_legal))
            except ValueError:
                continue

        return predictions

    def evaluate_puzzle(self, puzzle_data, max_moves=10):
        """
        Evaluate a single puzzle.

        Args:
            puzzle_data: Dictionary with puzzle information
            max_moves: Maximum number of moves to try in the solution

        Returns:
            Dictionary with evaluation results
        """
        board = chess.Board(puzzle_data["fen"])
        solution_moves = puzzle_data["moves_uci"]

        results = {
            "puzzle_id": puzzle_data["puzzle_id"],
            "rating": puzzle_data["rating"],
            "themes": puzzle_data["themes"],
            "solution_length": len(solution_moves),
            "moves_tried": [],
            "first_move_correct": False,
            "fully_solved": False,
            "moves_correct": 0,
            "predictions": [],
        }

        # Try to solve the puzzle move by move
        for move_idx in range(0, len(solution_moves), 2):  # Only predict our moves (every other move)
            if move_idx >= max_moves:
                break

            # Apply opponent's move first (if not the first move)
            if move_idx > 0:
                opponent_move = chess.Move.from_uci(solution_moves[move_idx - 1])
                if opponent_move in board.legal_moves:
                    board.push(opponent_move)
                else:
                    # Opponent move is illegal - puzzle data might be corrupted
                    results["error"] = "Illegal opponent move in solution"
                    break

            # Predict our move
            expected_move = solution_moves[move_idx]
            predictions = self.predict_move(board, top_k=5)

            if not predictions:
                results["error"] = "Model produced no valid predictions"
                break

            predicted_move = predictions[0][0]
            predicted_prob = predictions[0][1]
            is_correct = predicted_move == expected_move

            results["moves_tried"].append(
                {
                    "move_number": move_idx // 2 + 1,
                    "expected": expected_move,
                    "predicted": predicted_move,
                    "probability": predicted_prob,
                    "correct": is_correct,
                    "top_5_predictions": [{"move": m, "prob": p, "legal": l} for m, p, l in predictions],
                }
            )

            if is_correct:
                results["moves_correct"] += 1
                if move_idx == 0:
                    results["first_move_correct"] = True

                # Apply our correct move
                our_move = chess.Move.from_uci(predicted_move)
                board.push(our_move)
            else:
                # Wrong move - puzzle failed
                break

        # Check if fully solved
        if results["moves_correct"] == (len(solution_moves) + 1) // 2:
            results["fully_solved"] = True

        return results

    def evaluate_dataset(self, dataset, num_puzzles=None):
        """
        Evaluate the model on a puzzle dataset.

        Args:
            dataset: LichessPuzzleFullSolutionDataset
            num_puzzles: Number of puzzles to evaluate (None = all)

        Returns:
            Dictionary with aggregate results
        """
        num_puzzles = min(num_puzzles or len(dataset), len(dataset))

        print(f"Evaluating {num_puzzles} puzzles...")

        results = {
            "num_puzzles": num_puzzles,
            "first_move_accuracy": 0,
            "full_solution_accuracy": 0,
            "average_moves_correct": 0,
            "by_rating": {},
            "by_theme": {},
            "puzzle_results": [],
        }

        first_move_correct = 0
        fully_solved = 0
        total_moves_correct = 0
        total_moves = 0

        # Track by rating buckets
        rating_buckets = {
            "0-1000": {"first": 0, "full": 0, "total": 0},
            "1000-1500": {"first": 0, "full": 0, "total": 0},
            "1500-2000": {"first": 0, "full": 0, "total": 0},
            "2000-2500": {"first": 0, "full": 0, "total": 0},
            "2500+": {"first": 0, "full": 0, "total": 0},
        }

        # Track by theme
        theme_stats = {}

        for i in tqdm(range(num_puzzles), desc="Evaluating puzzles"):
            puzzle_data = dataset[i]
            puzzle_result = self.evaluate_puzzle(puzzle_data)

            # Aggregate statistics
            if puzzle_result["first_move_correct"]:
                first_move_correct += 1
            if puzzle_result["fully_solved"]:
                fully_solved += 1

            total_moves_correct += puzzle_result["moves_correct"]
            total_moves += puzzle_result["solution_length"] // 2 + 1

            # Rating bucket
            rating = puzzle_result["rating"]
            if rating < 1000:
                bucket = "0-1000"
            elif rating < 1500:
                bucket = "1000-1500"
            elif rating < 2000:
                bucket = "1500-2000"
            elif rating < 2500:
                bucket = "2000-2500"
            else:
                bucket = "2500+"

            rating_buckets[bucket]["total"] += 1
            if puzzle_result["first_move_correct"]:
                rating_buckets[bucket]["first"] += 1
            if puzzle_result["fully_solved"]:
                rating_buckets[bucket]["full"] += 1

            # Theme statistics
            for theme in puzzle_result["themes"]:
                if theme not in theme_stats:
                    theme_stats[theme] = {"first": 0, "full": 0, "total": 0}
                theme_stats[theme]["total"] += 1
                if puzzle_result["first_move_correct"]:
                    theme_stats[theme]["first"] += 1
                if puzzle_result["fully_solved"]:
                    theme_stats[theme]["full"] += 1

            results["puzzle_results"].append(puzzle_result)

        # Calculate aggregate metrics
        results["first_move_accuracy"] = 100.0 * first_move_correct / num_puzzles
        results["full_solution_accuracy"] = 100.0 * fully_solved / num_puzzles
        results["average_moves_correct"] = total_moves_correct / num_puzzles
        results["move_accuracy"] = 100.0 * total_moves_correct / total_moves if total_moves > 0 else 0

        # Rating bucket statistics
        for bucket, stats in rating_buckets.items():
            if stats["total"] > 0:
                results["by_rating"][bucket] = {
                    "count": stats["total"],
                    "first_move_accuracy": 100.0 * stats["first"] / stats["total"],
                    "full_solution_accuracy": 100.0 * stats["full"] / stats["total"],
                }

        # Theme statistics (top 20 themes by frequency)
        sorted_themes = sorted(theme_stats.items(), key=lambda x: x[1]["total"], reverse=True)[:20]
        for theme, stats in sorted_themes:
            results["by_theme"][theme] = {
                "count": stats["total"],
                "first_move_accuracy": 100.0 * stats["first"] / stats["total"],
                "full_solution_accuracy": 100.0 * stats["full"] / stats["total"],
            }

        return results


def main():
    parser = argparse.ArgumentParser(description="Evaluate Position2Move model on chess puzzles")
    parser.add_argument("--model", type=str, required=True, help="Path to model checkpoint")
    parser.add_argument(
        "--puzzle-data", type=str, default="data/lichess_db_puzzle.csv.zst", help="Path to puzzle .csv.zst file"
    )
    parser.add_argument("--num-puzzles", type=int, default=1000, help="Number of puzzles to evaluate")
    parser.add_argument("--min-rating", type=int, default=None, help="Minimum puzzle rating")
    parser.add_argument("--max-rating", type=int, default=None, help="Maximum puzzle rating")
    parser.add_argument("--themes", type=str, default=None, help="Comma-separated puzzle themes to filter by")
    parser.add_argument("--output", type=str, default=None, help="Output JSON file for results")

    args = parser.parse_args()

    # Parse themes
    themes = args.themes.split(",") if args.themes else None

    # Setup device
    device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
    print(f"Using device: {device}")

    # Load model
    print(f"\nLoading model from {args.model}...")
    model_path = Path(args.model)

    # Support both .pth and .safetensors formats
    if model_path.suffix == ".safetensors":
        # Load config from same directory
        from safetensors import safe_open
        import json

        config_path = model_path.parent / "config.json"
        with open(config_path, "r") as f:
            config = json.load(f)

        model = Position2MoveModel(**config)

        # Load weights from safetensors
        with safe_open(str(model_path), framework="pt", device=str(device)) as f:
            state_dict = {k: f.get_tensor(k) for k in f.keys()}

            # Handle compiled model prefix (_orig_mod.)
            if any(k.startswith("_orig_mod.") for k in state_dict.keys()):
                state_dict = {k.replace("_orig_mod.", ""): v for k, v in state_dict.items()}

            model.load_state_dict(state_dict)

        print(f"Model loaded from safetensors")
    else:
        # Load from .pth checkpoint
        checkpoint = torch.load(args.model, map_location=device, weights_only=False)
        config = checkpoint["config"]

        model = Position2MoveModel(**config)
        model.load_state_dict(checkpoint["model_state_dict"])
        print(f"Model loaded (epoch {checkpoint.get('epoch', 'unknown')})")

    # Load puzzle dataset
    print(f"\nLoading puzzle dataset...")
    dataset = LichessPuzzleFullSolutionDataset(
        puzzle_path=args.puzzle_data,
        min_rating=args.min_rating,
        max_rating=args.max_rating,
        themes=themes,
        max_puzzles=args.num_puzzles,
    )

    # Evaluate
    print("\n" + "=" * 70)
    print("Starting evaluation")
    print("=" * 70)

    evaluator = PuzzleEvaluator(model, device=device)
    results = evaluator.evaluate_dataset(dataset, num_puzzles=args.num_puzzles)

    # Print summary
    print("\n" + "=" * 70)
    print("EVALUATION RESULTS")
    print("=" * 70)
    print(f"Total puzzles: {results['num_puzzles']}")
    print(f"First move accuracy: {results['first_move_accuracy']:.2f}%")
    print(f"Full solution accuracy: {results['full_solution_accuracy']:.2f}%")
    print(f"Move accuracy: {results['move_accuracy']:.2f}%")
    print(f"Average moves correct: {results['average_moves_correct']:.2f}")

    print("\n" + "-" * 70)
    print("By Rating:")
    print("-" * 70)
    for rating, stats in sorted(results["by_rating"].items()):
        print(
            f"  {rating:>12}: {stats['count']:4} puzzles | "
            f"First: {stats['first_move_accuracy']:5.2f}% | "
            f"Full: {stats['full_solution_accuracy']:5.2f}%"
        )

    print("\n" + "-" * 70)
    print("Top Themes:")
    print("-" * 70)
    for theme, stats in list(results["by_theme"].items())[:10]:
        print(
            f"  {theme:>20}: {stats['count']:4} puzzles | "
            f"First: {stats['first_move_accuracy']:5.2f}% | "
            f"Full: {stats['full_solution_accuracy']:5.2f}%"
        )

    # Save results
    if args.output:
        output_path = args.output
    else:
        timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
        output_path = f"results/puzzle_eval_{timestamp}.json"

    output_path = Path(output_path)
    output_path.parent.mkdir(parents=True, exist_ok=True)

    # Don't save individual puzzle results to keep file size manageable
    results_summary = {k: v for k, v in results.items() if k != "puzzle_results"}
    results_summary["num_puzzles_detailed"] = len(results["puzzle_results"])

    with open(output_path, "w") as f:
        json.dump(results_summary, f, indent=2)

    print(f"\nResults saved to {output_path}")
    print("=" * 70)


if __name__ == "__main__":
    main()