package figures

import (
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
)

var ConfigFileNotFoundErr = errors.New("config file for provided path not found")

// fileExists checks if a file exists at a given path
func fileExists(path string) bool {
	if _, err := os.Stat(path); os.IsNotExist(err) {
		return false
	}

	return true
}

type figuration struct {
	applicationName string
}

// NewFiguration creates a new figuration for the provided application
func NewFiguration(applicationName string) figuration {
	return figuration{
		applicationName: applicationName,
	}
}

// GetConfigFilePath returns the path of a given file within the UserConfigDir.
func (fig figuration) GetConfigFilePath(filename string) (string, error) {
	configDir, err := os.UserConfigDir()
	if err != nil {
		return "", fmt.Errorf("error getting current config: %w", err)
	}

	// Get or make config dir path
	configDir = filepath.Join(configDir, fig.applicationName)
	_ = os.MkdirAll(configDir, 0o755)

	// Get the path to the provided file name within the config directory
	configFilePath := filepath.Join(configDir, filename)

	return configFilePath, err
}

// ReadConfig populates a provided struct with the data in config file of a given name
func (fig figuration) ReadConfig(name string, data interface{}) error {
	configPath, err := fig.GetConfigFilePath(name)
	if err != nil {
		return err
	}

	if !fileExists(configPath) {
		return fmt.Errorf("error reading config from file %s: %w", name, ConfigFileNotFoundErr)
	}

	content, err := ioutil.ReadFile(configPath)
	if err != nil {
		return fmt.Errorf("error reading config from file: %w", err)
	}

	err = json.Unmarshal(content, data)
	if err != nil {
		return fmt.Errorf("failed parsing json from config file: %w", err)
	}

	return nil
}

// WriteConfig writes data from the provided struct to the config file with the provided name
func (fig figuration) WriteConfig(name string, data interface{}) error {
	configPath, err := fig.GetConfigFilePath(name)
	if err != nil {
		return err
	}

	contents, err := json.Marshal(data)
	if err != nil {
		return fmt.Errorf("failed converting config to json: %w", err)
	}

	if err = ioutil.WriteFile(configPath, contents, 0o600); err != nil {
		return fmt.Errorf("error writing config to file: %w", err)
	}

	return nil
}

type Config interface {
	ApplicationName() string
	Filename() string
}

// ReadConfig populates the provided struct matching the Config interface with config values from the user's config store
func ReadConfig(config Config) error {
	return NewFiguration(config.ApplicationName()).ReadConfig(config.Filename(), config)
}

// WriteConfig writes the provided struct matching the Config interface to the users config store
func WriteConfig(config Config) error {
	return NewFiguration(config.ApplicationName()).WriteConfig(config.Filename(), config)
}