from __future__ import annotations

import json
from dataclasses import dataclass
from pathlib import Path

from tcga_downloader.logger import get_logger

logger = get_logger("config")


@dataclass
class QueryConfig:
    project: str
    data_type: str
    sample_type: str | None = None
    platform: str | None = None
    max_files: int = 1000


@dataclass
class DownloadConfig:
    out_dir: str
    processes: int = 4
    retries: int = 3
    token: str | None = None


@dataclass
class Config:
    query: QueryConfig
    download: DownloadConfig
    log_file: str | None = None
    verbose: bool = False


def load_config(path: Path) -> Config:
    """Load configuration from JSON or YAML file."""
    if not path.exists():
        raise FileNotFoundError(f"Config file not found: {path}")

    suffix = path.suffix.lower()

    if suffix == ".json":
        with path.open() as f:
            data = json.load(f)
    elif suffix in {".yaml", ".yml"}:
        try:
            import yaml

            with path.open() as f:
                data = yaml.safe_load(f)
        except ImportError as e:
            raise ImportError(
                "PyYAML is required for YAML config files. Install with: pip install pyyaml"
            ) from e
    else:
        raise ValueError(f"Unsupported config format: {suffix}")

    return _parse_config(data)


def _parse_config(data: dict) -> Config:
    query_data = data.get("query", {})
    download_data = data.get("download", {})

    query = QueryConfig(
        project=query_data.get("project"),
        data_type=query_data.get("data_type"),
        sample_type=query_data.get("sample_type"),
        platform=query_data.get("platform"),
        max_files=query_data.get("max_files", 1000),
    )

    download = DownloadConfig(
        out_dir=download_data.get("out_dir", "./data"),
        processes=download_data.get("processes", 4),
        retries=download_data.get("retries", 3),
        token=download_data.get("token"),
    )

    return Config(
        query=query,
        download=download,
        log_file=data.get("log_file"),
        verbose=data.get("verbose", False),
    )


def save_default_config(path: Path) -> None:
    """Save a default configuration template to file."""
    config = Config(
        query=QueryConfig(project="TCGA-BRCA", data_type="Gene Expression"),
        download=DownloadConfig(out_dir="./data"),
    )

    suffix = path.suffix.lower()

    if suffix == ".json":
        with path.open("w") as f:
            json.dump(_config_to_dict(config), f, indent=2)
    elif suffix in {".yaml", ".yml"}:
        try:
            import yaml

            with path.open("w") as f:
                yaml.dump(_config_to_dict(config), f, default_flow_style=False)
        except ImportError as e:
            raise ImportError(
                "PyYAML is required for YAML config files. Install with: pip install pyyaml"
            ) from e
    else:
        raise ValueError(f"Unsupported config format: {suffix}")

    logger.info("Default config saved to %s", path)


def _config_to_dict(config: Config) -> dict:
    """Convert Config dataclass to dictionary."""
    return {
        "query": {
            "project": config.query.project,
            "data_type": config.query.data_type,
            "sample_type": config.query.sample_type,
            "platform": config.query.platform,
            "max_files": config.query.max_files,
        },
        "download": {
            "out_dir": config.download.out_dir,
            "processes": config.download.processes,
            "retries": config.download.retries,
            "token": config.download.token,
        },
        "log_file": config.log_file,
        "verbose": config.verbose,
    }