"""Configuration loader for AYN Antivirus."""

from __future__ import annotations

import os
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, Dict, List, Optional

import yaml

from ayn_antivirus.constants import (
    DEFAULT_CONFIG_PATHS,
    DEFAULT_DASHBOARD_DB_PATH,
    DEFAULT_DASHBOARD_HOST,
    DEFAULT_DASHBOARD_PASSWORD,
    DEFAULT_DASHBOARD_PORT,
    DEFAULT_DASHBOARD_USERNAME,
    DEFAULT_DB_PATH,
    DEFAULT_LOG_PATH,
    DEFAULT_QUARANTINE_PATH,
    DEFAULT_SCAN_PATH,
    MAX_FILE_SIZE,
)


@dataclass
class Config:
    """Application configuration, loaded from YAML config files or environment variables."""

    scan_paths: List[str] = field(default_factory=lambda: [DEFAULT_SCAN_PATH])
    exclude_paths: List[str] = field(
        default_factory=lambda: ["/proc", "/sys", "/dev", "/run", "/snap"]
    )
    quarantine_path: str = DEFAULT_QUARANTINE_PATH
    db_path: str = DEFAULT_DB_PATH
    log_path: str = DEFAULT_LOG_PATH
    auto_quarantine: bool = False
    scan_schedule: str = "0 2 * * *"
    api_keys: Dict[str, str] = field(default_factory=dict)
    max_file_size: int = MAX_FILE_SIZE
    enable_yara: bool = True
    enable_heuristics: bool = True
    enable_realtime_monitor: bool = False
    dashboard_host: str = DEFAULT_DASHBOARD_HOST
    dashboard_port: int = DEFAULT_DASHBOARD_PORT
    dashboard_db_path: str = DEFAULT_DASHBOARD_DB_PATH
    dashboard_username: str = DEFAULT_DASHBOARD_USERNAME
    dashboard_password: str = DEFAULT_DASHBOARD_PASSWORD

    @classmethod
    def load(cls, config_path: Optional[str] = None) -> Config:
        """Load configuration from a YAML file, then overlay environment variables.

        Search order:
        1. Explicit ``config_path`` argument.
        2. /etc/ayn-antivirus/config.yaml
        3. ~/.ayn-antivirus/config.yaml
        4. Environment variables (always applied last as overrides).
        """
        data: Dict[str, Any] = {}

        paths_to_try = [config_path] if config_path else DEFAULT_CONFIG_PATHS
        for path in paths_to_try:
            if path and Path(path).is_file():
                with open(path, "r") as fh:
                    data = yaml.safe_load(fh) or {}
                break

        defaults = cls()
        config = cls(
            scan_paths=data.get("scan_paths", defaults.scan_paths),
            exclude_paths=data.get("exclude_paths", defaults.exclude_paths),
            quarantine_path=data.get("quarantine_path", DEFAULT_QUARANTINE_PATH),
            db_path=data.get("db_path", DEFAULT_DB_PATH),
            log_path=data.get("log_path", DEFAULT_LOG_PATH),
            auto_quarantine=data.get("auto_quarantine", False),
            scan_schedule=data.get("scan_schedule", "0 2 * * *"),
            api_keys=data.get("api_keys", {}),
            max_file_size=data.get("max_file_size", MAX_FILE_SIZE),
            enable_yara=data.get("enable_yara", True),
            enable_heuristics=data.get("enable_heuristics", True),
            enable_realtime_monitor=data.get("enable_realtime_monitor", False),
            dashboard_host=data.get("dashboard_host", DEFAULT_DASHBOARD_HOST),
            dashboard_port=data.get("dashboard_port", DEFAULT_DASHBOARD_PORT),
            dashboard_db_path=data.get("dashboard_db_path", DEFAULT_DASHBOARD_DB_PATH),
            dashboard_username=data.get("dashboard_username", DEFAULT_DASHBOARD_USERNAME),
            dashboard_password=data.get("dashboard_password", DEFAULT_DASHBOARD_PASSWORD),
        )

        # --- Environment variable overrides ---
        config._apply_env_overrides()

        return config

    def _apply_env_overrides(self) -> None:
        """Override config fields with AYN_* environment variables when set."""
        if os.getenv("AYN_SCAN_PATH"):
            self.scan_paths = [p.strip() for p in os.environ["AYN_SCAN_PATH"].split(",")]

        if os.getenv("AYN_QUARANTINE_PATH"):
            self.quarantine_path = os.environ["AYN_QUARANTINE_PATH"]

        if os.getenv("AYN_DB_PATH"):
            self.db_path = os.environ["AYN_DB_PATH"]

        if os.getenv("AYN_LOG_PATH"):
            self.log_path = os.environ["AYN_LOG_PATH"]

        if os.getenv("AYN_AUTO_QUARANTINE"):
            self.auto_quarantine = os.environ["AYN_AUTO_QUARANTINE"].lower() in (
                "true",
                "1",
                "yes",
            )

        if os.getenv("AYN_SCAN_SCHEDULE"):
            self.scan_schedule = os.environ["AYN_SCAN_SCHEDULE"]

        if os.getenv("AYN_MALWAREBAZAAR_API_KEY"):
            self.api_keys["malwarebazaar"] = os.environ["AYN_MALWAREBAZAAR_API_KEY"]

        if os.getenv("AYN_VIRUSTOTAL_API_KEY"):
            self.api_keys["virustotal"] = os.environ["AYN_VIRUSTOTAL_API_KEY"]

        if os.getenv("AYN_MAX_FILE_SIZE"):
            self.max_file_size = int(os.environ["AYN_MAX_FILE_SIZE"])

        if os.getenv("AYN_DASHBOARD_HOST"):
            self.dashboard_host = os.environ["AYN_DASHBOARD_HOST"]

        if os.getenv("AYN_DASHBOARD_PORT"):
            self.dashboard_port = int(os.environ["AYN_DASHBOARD_PORT"])

        if os.getenv("AYN_DASHBOARD_DB_PATH"):
            self.dashboard_db_path = os.environ["AYN_DASHBOARD_DB_PATH"]

        if os.getenv("AYN_DASHBOARD_USERNAME"):
            self.dashboard_username = os.environ["AYN_DASHBOARD_USERNAME"]

        if os.getenv("AYN_DASHBOARD_PASSWORD"):
            self.dashboard_password = os.environ["AYN_DASHBOARD_PASSWORD"]