package main

import (
	"encoding/json"
	"fmt"
	"io"
	"os"

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

type Configuration struct {
	Port              string `json:"port"`
	DatabaseDirectory string `json:"database_directory"`
}

func getDefaultConfig() Configuration {
	return Configuration{
		Port:              "8080",
		DatabaseDirectory: ".",
	}

}

func LoadConfiguration(configurationFilePath string) (Configuration, error) {
	config, err := fromFile(configurationFilePath)
	if err != nil {
		log.Info().Msg("failed to load configuration from file, using default values")
	}
	config.Port = os.Getenv("HTTP_PORT")
	config.DatabaseDirectory = os.Getenv("DATABASE_DIRECTORY")

	config = mergeConfig(getDefaultConfig(), config)

	err = checkConfiguration(&config)
	if err != nil {
		return config, err
	}

	return config, nil
}

func fromFile(filePath string) (Configuration, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return Configuration{}, err
	}

	jsonData, err := io.ReadAll(file)
	if err != nil {
		return Configuration{}, err
	}

	var config Configuration
	err = json.Unmarshal(jsonData, &config)
	if err != nil {
		return Configuration{}, err
	}
	return config, nil
}

func mergeConfig(base Configuration, override Configuration) Configuration {
	mergedConfig := base

	if override.Port != "" {
		mergedConfig.Port = override.Port
	}

	if override.DatabaseDirectory != "" {
		mergedConfig.DatabaseDirectory = override.DatabaseDirectory
	}

	return mergedConfig
}

func checkConfiguration(configuration *Configuration) error {
	databaseDirectory := configuration.DatabaseDirectory
	if !checkDirectoryPath(databaseDirectory) {
		return fmt.Errorf("database directory %s does not exist", databaseDirectory)
	}
	return nil
}

func checkDirectoryPath(directoryPath string) bool {
	_, err := os.Stat(directoryPath)
	return !os.IsNotExist(err)
}