package config

import (
	"fmt"
	"os"
	"time"

	"github.com/rs/zerolog/log"
	"github.com/spf13/viper"
)

// Config represents the application configuration
type Config struct {
	Server struct {
		Host string `mapstructure:"host"`
		Port int    `mapstructure:"port"`
	}
	Shutdown struct {
		Timeout time.Duration `mapstructure:"timeout"`
	}
}

// LoadConfig loads configuration from file, environment variables, and defaults
// Configuration priority: file > environment variables > defaults
// To specify a custom config file path, set DLC_CONFIG_FILE environment variable
func LoadConfig() (*Config, error) {
	v := viper.New()
	
	// Set default values
	v.SetDefault("server.host", "0.0.0.0")
	v.SetDefault("server.port", 8080)
	v.SetDefault("shutdown.timeout", 30*time.Second)
	
	// Check for custom config file path via environment variable
	if configFile := os.Getenv("DLC_CONFIG_FILE"); configFile != "" {
		v.SetConfigFile(configFile)
		log.Info().Str("config_file", configFile).Msg("Using custom config file path")
	} else {
		// Default: look for config.yaml in current directory
		v.SetConfigName("config")
		v.SetConfigType("yaml")
		v.AddConfigPath(".")
	}
	
	// Read config file if it exists
	if err := v.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
			// Config file was found but there was an error reading it
			log.Warn().Err(err).Msg("Error reading config file, using defaults")
		}
		// Config file not found, continue with environment variables and defaults
	} else {
		log.Info().Str("config_file", v.ConfigFileUsed()).Msg("Config file loaded")
	}
	
	// Bind environment variables
	v.AutomaticEnv()
	v.SetEnvPrefix("DLC") // DanceLessonsCoach prefix
	v.BindEnv("server.host", "DLC_SERVER_HOST")
	v.BindEnv("server.port", "DLC_SERVER_PORT")
	v.BindEnv("shutdown.timeout", "DLC_SHUTDOWN_TIMEOUT")
	
	// Unmarshal into Config struct
	var config Config
	if err := v.Unmarshal(&config); err != nil {
		log.Error().Err(err).Msg("Failed to unmarshal config")
		return nil, fmt.Errorf("config unmarshal error: %w", err)
	}
	
	log.Info().
		Str("host", config.Server.Host).
		Int("port", config.Server.Port).
		Dur("shutdown_timeout", config.Shutdown.Timeout).
		Msg("Configuration loaded")
	
	return &config, nil
}

// GetServerAddress returns the formatted server address (host:port)
func (c *Config) GetServerAddress() string {
	return fmt.Sprintf("%s:%d", c.Server.Host, c.Server.Port)
}