## Copyright © 2026 Olaf Kolkman
## SPDX-License-Identifier: GPL-3.0-or-later

from dataclasses import dataclass, field
import json
import os
from pathlib import Path

from cryptography.fernet import Fernet


BASE_DIR = Path(__file__).resolve().parent.parent.parent
DB_PATH = BASE_DIR / 'data' / 'linklog.db'
VERSION_FILE = BASE_DIR.parent / 'frontend' / 'version.json'


def normalize_public_url(value: str) -> str:
    value = value.strip().rstrip('/')
    if '://' in value:
        return value
    scheme = 'http' if value.startswith(('localhost', '127.0.0.1')) else 'https'
    return f'{scheme}://{value}'


def load_version() -> str:
    # frontend/version.json is the single source of truth for the app version, shared by backend and frontend.
    try:
        return json.loads(VERSION_FILE.read_text())['version']
    except (OSError, KeyError, ValueError):
        return '0.0.0'


@dataclass
class Settings:
    app_env: str = os.getenv('APP_ENV', 'development').lower()
    app_name: str = os.getenv('LINKLOG_APP_NAME', 'LinkLog')
    version: str = field(default_factory=load_version)
    database_url: str = os.getenv('LINKLOG_DATABASE_URL', f'sqlite:///{DB_PATH}')
    secret_key: str = os.getenv('LINKLOG_SECRET_KEY', 'dev-secret-key-change-me')
    data_encryption_key: str = os.getenv('LINKLOG_DATA_ENCRYPTION_KEY', '')
    token_expiry_minutes: int = int(os.getenv('LINKLOG_TOKEN_EXPIRY_MINUTES', '15'))
    refresh_token_expiry_days: int = int(os.getenv('LINKLOG_REFRESH_TOKEN_EXPIRY_DAYS', '30'))
    public_url: str = normalize_public_url(os.getenv('LINKLOG_PUBLIC_URL', 'linklog.example.com'))
    smtp_host: str = os.getenv('LINKLOG_SMTP_HOST', '')
    smtp_port: int = int(os.getenv('LINKLOG_SMTP_PORT', '587'))
    smtp_username: str = os.getenv('LINKLOG_SMTP_USERNAME', '')
    smtp_password: str = os.getenv('LINKLOG_SMTP_PASSWORD', '')
    smtp_from: str = os.getenv('LINKLOG_SMTP_FROM', 'LinkLog <no-reply@localhost>')
    smtp_use_tls: bool = os.getenv('LINKLOG_SMTP_USE_TLS', 'true').lower() in {'1', 'true', 'yes'}
    email_verification_expiry_hours: int = int(os.getenv('LINKLOG_EMAIL_VERIFICATION_EXPIRY_HOURS', '24'))
    password_reset_expiry_hours: int = int(os.getenv('LINKLOG_PASSWORD_RESET_EXPIRY_HOURS', '1'))
    mastodon_client_name: str = os.getenv('LINKLOG_MASTODON_CLIENT_NAME', 'LinkLog')
    mastodon_oauth_expiry_minutes: int = int(os.getenv('LINKLOG_MASTODON_OAUTH_EXPIRY_MINUTES', '10'))
    log_level: str = os.getenv('LINKLOG_LOG_LEVEL', 'INFO').upper()
    tracking_params: list[str] = None

    def __post_init__(self):
        if self.tracking_params is None:
            default_tracking_params = [
                'utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
                'utm_id', 'utm_name', 'gclid', 'fbclid', 'dclid', 'msclkid', 'mc_cid',
                'mc_eid', 'igshid', 'ga_source', 'ga_medium', 'ga_campaign', 'ga_place',
                'campaignid', 'hsa_cr', 'hsa_cam', 'hsa_grp', 'hsa_ad', 'hsa_src',
                'hsa_acc', 'hsa_net', 'hsa_mt', 'hsa_kw', 'hsa_ver', 'hsa_tgt',
            ]
            configured_params = os.getenv('LINKLOG_TRACKING_PARAMS')
            self.tracking_params = (
                [item.strip() for item in configured_params.split(',') if item.strip()]
                if configured_params
                else default_tracking_params
            )


settings = Settings()


def validate_configuration(values: Settings) -> None:
    if values.app_env == 'production':
        if not values.secret_key or values.secret_key == 'dev-secret-key-change-me':
            raise RuntimeError('LINKLOG_SECRET_KEY must be configured in production')
        if len(values.secret_key) < 32 or len(set(values.secret_key)) < 12:
            raise RuntimeError('LINKLOG_SECRET_KEY must be at least 32 characters with sufficient entropy')
        if not values.data_encryption_key:
            raise RuntimeError('LINKLOG_DATA_ENCRYPTION_KEY must be configured in production')

    if values.data_encryption_key:
        try:
            Fernet(values.data_encryption_key.encode('ascii'))
        except (ValueError, UnicodeEncodeError) as error:
            raise RuntimeError('LINKLOG_DATA_ENCRYPTION_KEY must be a valid Fernet key') from error