package config

import (
	"fmt"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/joho/godotenv"
	"log/slog"
)

const (
	// Environment variable prefix for the application
	envPrefix = "JUKEBOX_"
)

// Config holds all the configuration for the application
type Config struct {
	// Discord configuration
	DiscordToken     string
	DiscordGuildID   string
	DiscordChannelID string

	// Subsonic configuration
	SubsonicServer   string
	SubsonicUsername string
	SubsonicPassword string
	SubsonicVersion  string

	// Jukebox configuration
	AudioVolume float64
	TimeoutSec  int
}

// Load loads the configuration from environment variables and .env file
func Load() (*Config, error) {
	// Try to load .env file
	if err := godotenv.Load(); err != nil {
		slog.Info("No .env file found, using environment variables only")
	} else {
		slog.Info("Loaded environment variables from .env file")
	}
	
	// Load the raw values first
	rawGuildID := getEnv(envPrefix+"DISCORD_GUILD_ID", "")

	// Clean up Guild ID - ensure we have just the snowflake
	cleanGuildID := cleanSnowflake(rawGuildID)
	if cleanGuildID != rawGuildID && rawGuildID != "" {
		slog.Warn("Cleaned Discord Guild ID", "original", rawGuildID, "cleaned", cleanGuildID)
	}

	config := &Config{
		// Discord
		DiscordToken:     getEnv(envPrefix+"DISCORD_TOKEN", ""),
		DiscordGuildID:   cleanGuildID,
		DiscordChannelID: getEnv(envPrefix+"DISCORD_CHANNEL_ID", ""),

		// Subsonic
		SubsonicServer:   getEnv(envPrefix+"SUBSONIC_SERVER", ""),
		SubsonicUsername: getEnv(envPrefix+"SUBSONIC_USERNAME", ""),
		SubsonicPassword: getEnv(envPrefix+"SUBSONIC_PASSWORD", ""),
		SubsonicVersion:  getEnv(envPrefix+"SUBSONIC_VERSION", "1.16.1"),

		// Jukebox
		AudioVolume: getEnvFloat(envPrefix+"AUDIO_VOLUME", 0.5),
		TimeoutSec:  getEnvInt(envPrefix+"TIMEOUT_SEC", 30),
	}

	if err := config.validate(); err != nil {
		// Print helpful debug information
		PrintDebugInfo()
		return nil, err
	}

	return config, nil
}

// validate checks if the required configuration values are set
func (c *Config) validate() error {
	if c.DiscordToken == "" {
		return errorMissingConfig("discord token")
	}

	if c.SubsonicServer == "" {
		return errorMissingConfig("subsonic server")
	}

	if c.SubsonicUsername == "" {
		return errorMissingConfig("subsonic username")
	}

	if c.SubsonicPassword == "" {
		return errorMissingConfig("subsonic password")
	}

	return nil
}

// errorMissingConfig returns a formatted error for missing configuration
func errorMissingConfig(name string) error {
	return fmt.Errorf("%s is required", name)
}

// GetTimeout returns the timeout duration
func (c *Config) GetTimeout() time.Duration {
	return time.Duration(c.TimeoutSec) * time.Second
}

// getEnv gets an environment variable or returns a default value
func getEnv(key, defaultValue string) string {
	if value, exists := os.LookupEnv(key); exists {
		return value
	}
	return defaultValue
}

// getEnvInt gets an environment variable as an integer or returns a default value
func getEnvInt(key string, defaultValue int) int {
	if value, exists := os.LookupEnv(key); exists {
		if intValue, err := strconv.Atoi(value); err == nil {
			return intValue
		}
	}
	return defaultValue
}

// getEnvFloat gets an environment variable as a float or returns a default value
func getEnvFloat(key string, defaultValue float64) float64 {
	if value, exists := os.LookupEnv(key); exists {
		if floatValue, err := strconv.ParseFloat(value, 64); err == nil {
			return floatValue
		}
	}
	return defaultValue
}

// PrintDebugInfo prints helpful debugging information for environment variables
func PrintDebugInfo() {
	slog.Info("=== Configuration Debug Information ===")
	slog.Info("Required environment variables:")
	checkEnvVar(envPrefix + "DISCORD_TOKEN")
	checkEnvVar(envPrefix + "DISCORD_GUILD_ID")
	checkEnvVar(envPrefix + "SUBSONIC_SERVER")
	checkEnvVar(envPrefix + "SUBSONIC_USERNAME")
	checkEnvVar(envPrefix + "SUBSONIC_PASSWORD")
	
	slog.Info("Optional environment variables:")
	checkEnvVar(envPrefix + "DISCORD_CHANNEL_ID")
	checkEnvVar(envPrefix + "SUBSONIC_VERSION")
	checkEnvVar(envPrefix + "AUDIO_VOLUME")
	checkEnvVar(envPrefix + "TIMEOUT_SEC")
	
	slog.Info("Troubleshooting tips:")
	slog.Info("1. Your .env file is in the correct directory")
	slog.Info("2. All variable names have the JUKEBOX_ prefix")
	slog.Info("3. There are no spaces around the = sign in your .env file")
	slog.Info("   Example: JUKEBOX_DISCORD_TOKEN=your_token_here")
	slog.Info("4. Your .env file has been loaded (check for errors above)")
	slog.Info("===================================")
}

// checkEnvVar checks if an environment variable is set and prints its status
func checkEnvVar(name string) {
	if value, exists := os.LookupEnv(name); exists {
		// Mask sensitive values
		displayValue := value
		if contains(name, "TOKEN", "PASSWORD") {
			if len(displayValue) > 8 {
				displayValue = displayValue[:4] + "..." + displayValue[len(displayValue)-4:]
			} else {
				displayValue = "****"
			}
		}
		
		// Special handling for Guild ID to detect common issues
		if strings.Contains(name, "GUILD_ID") && strings.Contains(value, "=") {
			slog.Warn("Environment variable contains equals sign", 
				"name", name, 
				"raw_value", displayValue, 
				"cleaned_value", cleanSnowflake(value))
		} else {
			slog.Info("Environment variable check", "name", name, "value", displayValue, "status", "set")
		}
	} else {
		slog.Warn("Environment variable not set", "name", name)
	}
}

// contains checks if the string contains any of the substrings
func contains(str string, substrings ...string) bool {
	for _, substring := range substrings {
		if strings.Contains(str, substring) {
			return true
		}
	}
	return false
}

// cleanSnowflake cleans a Discord snowflake (ID) from potential contamination
// This handles cases where the ID might include the variable name or other text
func cleanSnowflake(input string) string {
	// If the input contains an equals sign, it might be contaminated
	if strings.Contains(input, "=") {
		parts := strings.SplitN(input, "=", 2)
		if len(parts) == 2 {
			input = parts[1] // Take the part after the equals sign
		}
	}

	// Extract only digits
	var result strings.Builder
	for _, char := range input {
		if char >= '0' && char <= '9' {
			result.WriteRune(char)
		}
	}

	return result.String()
}