package config

import (
	"fmt"
	"time"

	"github.com/spf13/viper"
)

type Config struct {
	Server   ServerConfig   `mapstructure:"server"`
	Database DatabaseConfig `mapstructure:"database"`
	Auth     AuthConfig     `mapstructure:"auth"`
	Fetcher  FetcherConfig  `mapstructure:"fetcher"`
	Recycle  RecycleConfig  `mapstructure:"recycle"`
	App      AppConfig      `mapstructure:"app"`
}

type ServerConfig struct {
	Host         string        `mapstructure:"host"`
	Port         int           `mapstructure:"port"`
	ReadTimeout  time.Duration `mapstructure:"read_timeout"`
	WriteTimeout time.Duration `mapstructure:"write_timeout"`
	BodyLimit    int           `mapstructure:"body_limit"`
	FrontendDir  string        `mapstructure:"frontend_dir"`
}

type DatabaseConfig struct {
	Path string `mapstructure:"path"`
}

type AuthConfig struct {
	AdminToken    string   `mapstructure:"admin_token"`
	DownloadToken string   `mapstructure:"download_token"`
	DownloadHosts []string `mapstructure:"download_hosts"`
}

type FetcherConfig struct {
	DefaultTimeout      time.Duration `mapstructure:"default_timeout"`
	DefaultUserAgent    string        `mapstructure:"default_user_agent"`
	DefaultFlowUA       string        `mapstructure:"default_flow_user_agent"`
	Concurrency         int           `mapstructure:"concurrency"`
	ConcurrencyWait     time.Duration `mapstructure:"concurrency_wait"`
	CacheTTL            time.Duration `mapstructure:"cache_ttl"`
	CacheStaleOnError   bool          `mapstructure:"cache_stale_on_error"`
	MaxSourceUrls       int           `mapstructure:"max_source_urls"`
	MaxResponseBytes    int           `mapstructure:"max_response_bytes"`
	MaxTotalBytes       int           `mapstructure:"max_total_bytes"`
	ProxyURL            string        `mapstructure:"proxy_url"`
}

type RecycleConfig struct {
	MaxEntries int `mapstructure:"max_entries"`
}

type AppConfig struct {
	Name    string `mapstructure:"name"`
	Version string `mapstructure:"version"`
}

func defaults() {
	viper.SetDefault("server.host", "0.0.0.0")
	viper.SetDefault("server.port", 3000)
	viper.SetDefault("server.read_timeout", 30*time.Second)
	viper.SetDefault("server.write_timeout", 60*time.Second)
	viper.SetDefault("server.body_limit", 4*1024*1024)
	viper.SetDefault("server.frontend_dir", "./frontend/dist")
	viper.SetDefault("database.path", "./data/sub-store.db")
	viper.SetDefault("auth.admin_token", "")
	viper.SetDefault("auth.download_token", "")
	viper.SetDefault("auth.download_hosts", []string{})
	viper.SetDefault("fetcher.default_timeout", 30*time.Second)
	viper.SetDefault("fetcher.default_user_agent", "clash.meta/v1.19.24")
	viper.SetDefault("fetcher.default_flow_user_agent", "clash.meta/v1.19.24")
	viper.SetDefault("fetcher.concurrency", 3)
	viper.SetDefault("fetcher.concurrency_wait", 0*time.Second)
	viper.SetDefault("fetcher.cache_ttl", 300*time.Second)
	viper.SetDefault("fetcher.cache_stale_on_error", true)
	viper.SetDefault("fetcher.max_source_urls", 8)
	viper.SetDefault("fetcher.max_response_bytes", 2*1024*1024)
	viper.SetDefault("fetcher.max_total_bytes", 12*1024*1024)
	viper.SetDefault("fetcher.proxy_url", "")
	viper.SetDefault("recycle.max_entries", 50)
	viper.SetDefault("app.name", "Sub-Store")
	viper.SetDefault("app.version", "1.0.0")
}

func Load(configPath string) (*Config, error) {
	defaults()

	if configPath != "" {
		viper.SetConfigFile(configPath)
	} else {
		viper.SetConfigName("config")
		viper.SetConfigType("yaml")
		viper.AddConfigPath(".")
		viper.AddConfigPath("./config")
	}

	viper.SetEnvPrefix("SUB_STORE")
	viper.AutomaticEnv()

	if err := viper.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
			return nil, fmt.Errorf("failed to read config: %w", err)
		}
	}

	var cfg Config
	if err := viper.Unmarshal(&cfg); err != nil {
		return nil, fmt.Errorf("failed to unmarshal config: %w", err)
	}

	if cfg.Auth.AdminToken == "" {
		return nil, fmt.Errorf("auth.admin_token is required (set in config.yaml or SUB_STORE_AUTH_ADMIN_TOKEN env)")
	}
	if cfg.Auth.DownloadToken == "" {
		return nil, fmt.Errorf("auth.download_token is required (set in config.yaml or SUB_STORE_AUTH_DOWNLOAD_TOKEN env)")
	}

	return &cfg, nil
}