package utils

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

func LoadUrls(filename string) ([]string, error) {
	file, err := os.OpenFile(filename, os.O_RDONLY, 0644)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return []string{}, nil
		}
		return nil, fmt.Errorf("failed to open file, %w", err)
	}

	b, err := io.ReadAll(file)
	if err != nil {
		return nil, fmt.Errorf("failed to read file, %w", err)
	}

	var res []string
	if err := json.Unmarshal(b, &res); err != nil {
		return nil, fmt.Errorf("failed to unmarshal from json, %w", err)
	}

	return res, nil
}

func SaveUrls(filename string, urls []string) error {
	file, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644)
	if err != nil {
		return fmt.Errorf("failed to open file, %w", err)
	}

	b, err := json.Marshal(urls)
	if err != nil {
		return fmt.Errorf("failed to marshal to json, %w", err)
	}

	if _, err := file.Write(b); err != nil {
		return fmt.Errorf("failed to write to file, %w", err)
	}
	return nil
}