package loaders

import (
	"encoding/json"
	"os"
)

/*
	This is a simple database system that peforms CRUD operations on a JSON file.
	It will be a proper database system in the future, but for now it will be a JSON file.
	Hope this is understandable for future coders.
*/

type DataLoader interface {
	Read(filename string) (interface{}, error)
	Write(filename string, data interface{}) error
}

type JSON struct{}

func (l *JSON) Read(filename string) (interface{}, error) {
	file, err := os.Open(filename)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	bytes, err := os.ReadFile(filename)
	if err != nil {
		return nil, err
	}

	data := make(map[string]interface{})
	err = json.Unmarshal(bytes, &data)
	if err != nil {
		return nil, err
	}

	return data, nil
}

func (l *JSON) Write(filename string, data interface{}) error {
	existingData, err := l.Read(filename)
	if err != nil {
		return err
	}

	newData := data.(map[string]interface{})
	for k, v := range existingData.(map[string]interface{}) {
		if newV, ok := newData[k]; ok {
			newData[k] = newV
		} else {
			newData[k] = v
		}
	}

	bytes, err := json.MarshalIndent(newData, "", "  ")
	if err != nil {
		return err
	}

	err = os.WriteFile(filename, bytes, 0644)
	if err != nil {
		return err
	}

	return nil
}