"""Configuration management."""
import json
import os
from typing import Any, Callable

DEFAULT_CONFIG = {
    "port": 7860,
    "host": "0.0.0.0",
    "retry_attempts": 3,
    "retry_delay_sec": 2,
    "request_timeout_sec": 180,
    "gemini_bl": "boq_assistant-bard-web-server_20260525.09_p0",
    "auth_user": None,
    "xsrf_token": None,
    "default_model": "gemini-3.5-flash",
    "log_requests": True,
    "cookie_file": None,
    "proxy": None,
    "api_keys": [],
}

CONFIG = dict(DEFAULT_CONFIG)


def _env_value(*names: str) -> str | None:
    """Return the first non-empty environment variable value."""
    for name in names:
        value = os.environ.get(name)
        if value is not None and value != "":
            return value
    return None


def _to_bool(value: str) -> bool:
    return value.strip().lower() in {"1", "true", "yes", "y", "on"}


def _to_int(value: str) -> int:
    return int(value.strip())


def _to_nullable_str(value: str) -> str | None:
    value = value.strip()
    if value.lower() in {"", "none", "null"}:
        return None
    return value


def _to_list(value: str) -> list[str]:
    return [item.strip() for item in value.split(",") if item.strip()]


def load_config(path: str = None):
    """Load config from JSON file."""
    if path and os.path.exists(path):
        with open(path, encoding="utf-8") as f:
            CONFIG.update(json.load(f))
    return CONFIG


def apply_env_overrides():
    """Apply environment variables with highest priority.

    Supported variables are documented in .env.example. Short names such as PORT
    are accepted first, and GEMINI_WEB2API_* aliases are also supported.
    """
    scalar_mappings: list[tuple[str, Callable[[str], Any], tuple[str, ...]]] = [
        ("port", _to_int, ("PORT", "GEMINI_WEB2API_PORT")),
        ("host", str, ("HOST", "GEMINI_WEB2API_HOST")),
        ("retry_attempts", _to_int, ("RETRY_ATTEMPTS", "GEMINI_WEB2API_RETRY_ATTEMPTS")),
        ("retry_delay_sec", _to_int, ("RETRY_DELAY_SEC", "GEMINI_WEB2API_RETRY_DELAY_SEC")),
        ("request_timeout_sec", _to_int, ("REQUEST_TIMEOUT_SEC", "GEMINI_WEB2API_REQUEST_TIMEOUT_SEC")),
        ("gemini_bl", str, ("GEMINI_BL", "GEMINI_WEB2API_GEMINI_BL")),
        ("auth_user", _to_nullable_str, ("AUTH_USER", "GEMINI_AUTH_USER", "GEMINI_WEB2API_AUTH_USER")),
        ("xsrf_token", _to_nullable_str, ("XSRF_TOKEN", "GEMINI_XSRF_TOKEN", "GEMINI_WEB2API_XSRF_TOKEN")),
        ("default_model", str, ("DEFAULT_MODEL", "GEMINI_DEFAULT_MODEL", "GEMINI_WEB2API_DEFAULT_MODEL")),
        ("log_requests", _to_bool, ("LOG_REQUESTS", "GEMINI_WEB2API_LOG_REQUESTS")),
        ("cookie_file", _to_nullable_str, ("COOKIE_FILE", "GEMINI_COOKIE_FILE", "GEMINI_WEB2API_COOKIE_FILE")),
        ("proxy", _to_nullable_str, ("PROXY", "HTTP_PROXY_URL", "GEMINI_WEB2API_PROXY")),
    ]

    for key, caster, names in scalar_mappings:
        value = _env_value(*names)
        if value is None:
            continue
        CONFIG[key] = caster(value)

    # API_KEY is a convenience single-key value and intentionally wins over API_KEYS.
    api_key = _env_value("API_KEY", "GEMINI_API_KEY", "GEMINI_WEB2API_API_KEY")
    if api_key is not None:
        CONFIG["api_keys"] = [api_key.strip()] if api_key.strip() else []
        return CONFIG

    api_keys = _env_value("API_KEYS", "GEMINI_API_KEYS", "GEMINI_WEB2API_API_KEYS")
    if api_keys is not None:
        CONFIG["api_keys"] = _to_list(api_keys)

    return CONFIG


def find_config():
    """Search for config file in standard locations."""
    for p in ["./config.json", os.path.expanduser("~/.config/gemini-web2api/config.json")]:
        if os.path.exists(p):
            return p
    return None