package engine

import (
	"fmt"
	"os"
	"path/filepath"

	"github.com/spf13/viper"
)

type Config struct {
	// DepoPath is the path to the jade depository. Default ~/jade-depository
	DepoPath string `mapstructure:"depo_path"`
	// ConfigPath is the path to the config directory. Default ~/.config/jade/config.yml
	ConfigPath string `mapstructure:"config_path"`
	// TagPrefix is the prefix used for tags in notes. Default "+"
	TagPrefix string `mapstructure:"tag_prefix"`
}

// getDefaultDepoPath returns the default depository path
func getDefaultDepoPath() string {
	home, err := os.UserHomeDir()
	if err != nil {
		return "./jade-depository"
	}
	return filepath.Join(home, "jade-depository")
}

// getDefaultConfigPath returns the default config directory path
func getDefaultConfigPath() string {
	home, err := os.UserHomeDir()
	if err != nil {
		return "./.config/jade/config.yml"
	}
	return filepath.Join(home, ".config", "jade", "config.yml")
}

// initConfig initializes the configuration using Viper
// Precedence order: flags > environment variables > config file > defaults
func initConfig(cfgPath, depoPath string) (*Config, error) {
	// Set up environment variable support
	viper.SetEnvPrefix("JADE")
	viper.AutomaticEnv()

	// Set defaults
	viper.SetDefault("depo_path", getDefaultDepoPath())
	viper.SetDefault("config_path", getDefaultConfigPath())
	viper.SetDefault("tag_prefix", "+")

	// Determine config file location
	configDir := cfgPath
	if configDir == "" {
		configDir = getDefaultConfigPath()
	}

	// Ensure config directory exists
	if err := os.MkdirAll(configDir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create config directory: %w", err)
	}

	// Set up config file
	viper.SetConfigName("config")
	viper.SetConfigType("yaml")
	viper.AddConfigPath(configDir)

	// Try to read existing config file
	if err := viper.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); ok {
			// Config file not found, create it with defaults
			configFilePath := filepath.Join(configDir, "config.yaml")
			if err := viper.SafeWriteConfigAs(configFilePath); err != nil {
				return nil, fmt.Errorf("failed to create config file: %w", err)
			}
		} else {
			// Config file was found but another error occurred
			return nil, fmt.Errorf("error reading config file: %w", err)
		}
	}

	// Override with flags if provided (highest precedence)
	if depoPath != "" {
		viper.Set("depo_path", depoPath)
	}
	if cfgPath != "" {
		viper.Set("config_path", cfgPath)
	}

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

	// Write config back to persist any changes (e.g., from flags or env vars)
	if err := viper.WriteConfig(); err != nil {
		return nil, fmt.Errorf("failed to write config: %w", err)
	}

	return cfg, nil
}