// Package config provides application configuration via Viper.
package config

import (
	"errors"
	"fmt"
	"log/slog"

	"github.com/spf13/viper"
	"go.uber.org/fx"

	"git.eeqj.de/sneak/upaas/internal/globals"
	"git.eeqj.de/sneak/upaas/internal/logger"
)

// defaultPort is the default HTTP server port.
const defaultPort = 8080

// Params contains dependencies for Config.
type Params struct {
	fx.In

	Globals *globals.Globals
	Logger  *logger.Logger
}

// Config holds application configuration.
type Config struct {
	Port            int
	Debug           bool
	DataDir         string
	DockerHost      string
	SentryDSN       string
	MaintenanceMode bool
	MetricsUsername string
	MetricsPassword string
	SessionSecret   string
	params          *Params
	log             *slog.Logger
}

// New creates a new Config instance from environment and config files.
func New(_ fx.Lifecycle, params Params) (*Config, error) {
	log := params.Logger.Get()

	name := params.Globals.Appname
	if name == "" {
		name = "upaas"
	}

	setupViper(name)

	cfg, err := buildConfig(log, &params)
	if err != nil {
		return nil, err
	}

	configureDebugLogging(cfg, params)

	return cfg, nil
}

func setupViper(name string) {
	// Config file settings
	viper.SetConfigName(name)
	viper.SetConfigType("yaml")
	viper.AddConfigPath("/etc/" + name)
	viper.AddConfigPath("$HOME/.config/" + name)
	viper.AddConfigPath(".")

	// Environment variables override everything
	viper.SetEnvPrefix("UPAAS")
	viper.AutomaticEnv()

	// Defaults
	viper.SetDefault("PORT", defaultPort)
	viper.SetDefault("DEBUG", false)
	viper.SetDefault("DATA_DIR", "./data")
	viper.SetDefault("DOCKER_HOST", "unix:///var/run/docker.sock")
	viper.SetDefault("SENTRY_DSN", "")
	viper.SetDefault("MAINTENANCE_MODE", false)
	viper.SetDefault("METRICS_USERNAME", "")
	viper.SetDefault("METRICS_PASSWORD", "")
	viper.SetDefault("SESSION_SECRET", "")
}

func buildConfig(log *slog.Logger, params *Params) (*Config, error) {
	// Read config file (optional)
	err := viper.ReadInConfig()
	if err != nil {
		var configFileNotFoundError viper.ConfigFileNotFoundError
		if !errors.As(err, &configFileNotFoundError) {
			log.Error("config file malformed", "error", err)

			return nil, fmt.Errorf("config file malformed: %w", err)
		}
		// Config file not found is OK
	}

	// Build config struct
	cfg := &Config{
		Port:            viper.GetInt("PORT"),
		Debug:           viper.GetBool("DEBUG"),
		DataDir:         viper.GetString("DATA_DIR"),
		DockerHost:      viper.GetString("DOCKER_HOST"),
		SentryDSN:       viper.GetString("SENTRY_DSN"),
		MaintenanceMode: viper.GetBool("MAINTENANCE_MODE"),
		MetricsUsername: viper.GetString("METRICS_USERNAME"),
		MetricsPassword: viper.GetString("METRICS_PASSWORD"),
		SessionSecret:   viper.GetString("SESSION_SECRET"),
		params:          params,
		log:             log,
	}

	// Generate session secret if not set
	if cfg.SessionSecret == "" {
		cfg.SessionSecret = "change-me-in-production-please"

		log.Warn(
			"using default session secret, " +
				"set UPAAS_SESSION_SECRET in production",
		)
	}

	return cfg, nil
}

func configureDebugLogging(cfg *Config, params Params) {
	// Enable debug logging if configured
	if cfg.Debug {
		params.Logger.EnableDebugLogging()
		cfg.log = params.Logger.Get()
	}
}

// DatabasePath returns the full path to the SQLite database file.
func (c *Config) DatabasePath() string {
	return c.DataDir + "/upaas.db"
}