"""Load static, competition-approved tasks."""

import os
import json
from pathlib import Path
from typing import Dict, List, Optional

# Get the dataset root (same folder as this file)
DATASET_ROOT = Path(__file__).parent

# Hardcoded competition tasks: Easy  Medium  Hard
STATIC_TASKS = {
    "easy": {
        "problem_id": "problem_1",
        "difficulty": "easy",
        "description": "String reversal with space normalization",
    },
    "medium": {
        "problem_id": "problem_10",
        "difficulty": "medium",
        "description": "Matrix 90 clockwise rotation",
    },
    "hard": {
        "problem_id": "problem_13",
        "difficulty": "hard",
        "description": "LRU cache with correct eviction policy",
    },
}


def load_problem(problem_id: str) -> Dict[str, any]:
    """
    Load a single problem from disk.
    
    Args:
        problem_id: e.g., "problem_1", "problem_10", "problem_13"
    
    Returns:
        {
            "code": str,          # buggy.py content
            "tests": str,         # test.py path (relative to problem folder)
            "metadata": dict,     # metadata.json
            "problem_dir": str,   # absolute path to problem folder
        }
    """
    problem_dir = DATASET_ROOT / problem_id
    
    if not problem_dir.exists():
        raise FileNotFoundError(f"Problem directory not found: {problem_dir}")
    
    # Load buggy code
    buggy_file = problem_dir / "buggy.py"
    code = buggy_file.read_text(encoding="utf-8")
    
    # Load metadata
    metadata_file = problem_dir / "metadata.json"
    metadata = json.loads(metadata_file.read_text(encoding="utf-8"))
    
    # Test file path (relative to problem root)
    test_path = str(problem_dir / "test.py")
    
    return {
        "code": code,
        "tests": test_path,
        "metadata": metadata,
        "problem_dir": str(problem_dir),
        "problem_id": problem_id,
    }


def get_hardcoded_task(difficulty: str) -> Dict[str, any]:
    """
    Get one of the three static competition tasks.
    
    Args:
        difficulty: "easy" | "medium" | "hard"
    
    Returns:
        Task dict with code, tests, metadata
    
    Raises:
        ValueError: if difficulty is not one of the three approved values
    """
    if difficulty not in STATIC_TASKS:
        raise ValueError(
            f"Invalid difficulty '{difficulty}'. "
            f"Must be one of: {list(STATIC_TASKS.keys())}"
        )
    
    task_info = STATIC_TASKS[difficulty]
    problem_id = task_info["problem_id"]
    
    return load_problem(problem_id)


def get_random_tasks():
    """
    DEPRECATED: Use get_hardcoded_task() instead.
    Kept for backward compatibility.
    """
    import warnings
    warnings.warn(
        "get_random_tasks() is deprecated. Use get_hardcoded_task('easy'|'medium'|'hard')",
        DeprecationWarning,
        stacklevel=2
    )
    # Return a default (easy)
    return get_hardcoded_task("easy")