Rewrite source reading

Switch from json to lines

main.go

@@ -1,14 +1,16 @@
 package main
 
 import (
+	"bufio"
 	"context"
-	"encoding/json"
 	"flag"
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 	"time"
 
@@ -27,17 +29,35 @@ func main() {
 	jobs := flag.Int("j", 5, "concurrent downloads")
 	rateLimit := flag.Float64("rate", 0, "maximum downloads per second (0 = no limit)")
 
+	inputFile := "-"
+	var outputDir string
+
 	flag.Parse()
 
 	args := flag.Args()
 
-	if len(args) != 2 {
-		fmt.Println("Usage: program <json-file> <output-dir>")
+	if len(args) == 1 {
+		outputDir = args[0]
+	} else if len(args) == 2 {
+		inputFile = args[0]
+		outputDir = args[1]
+	} else {
+		fmt.Println("Usage: program [OPTIONS] [input-file|-] <output-dir>")
 		os.Exit(1)
 	}
 
-	jsonFile := args[0]
-	outputDir := args[1]
+	// Создаем директорию для загрузок
+	if err := os.MkdirAll(outputDir, 0755); err != nil {
+		fmt.Printf("Error creating directory: %v\n", err)
+		os.Exit(1)
+	}
+
+	scanner, closer, err := createLineScanner(inputFile)
+	if err != nil {
+		fmt.Printf("Error reading source: %v\n", err)
+		os.Exit(1)
+	}
+	defer closer.Close()
 
 	httpClient = &http.Client{
 		Timeout: *timeout,
@@ -48,32 +68,26 @@ func main() {
 		limiter = rate.NewLimiter(rate.Limit(*rateLimit), 1)
 	}
 
-	// Создаем директорию для загрузок
-	if err := os.MkdirAll(outputDir, 0755); err != nil {
-		fmt.Printf("Error creating directory: %v\n", err)
-		os.Exit(1)
-	}
-
-	// Читаем JSON файл
-	data, err := os.ReadFile(jsonFile)
-	if err != nil {
-		fmt.Printf("Error reading JSON file: %v\n", err)
-		os.Exit(1)
-	}
-
-	// Парсим JSON в массив строк
-	var urls []string
-	if err := json.Unmarshal(data, &urls); err != nil {
-		fmt.Printf("Error parsing JSON: %v\n", err)
-		os.Exit(1)
-	}
-
 	// Семафор для ограничения параллелизма
 	sem := make(chan struct{}, *jobs)
 	var wg sync.WaitGroup
 
 	start := time.Now()
-	for i, url := range urls {
+	idx := 0
+
+	for scanner.Scan() {
+		url := strings.TrimSpace(scanner.Text())
+		if url == "" {
+			continue
+		}
+
+		idx++
+
+		if !isValidUrl(url) {
+			fmt.Printf("Warning: invalid url, skip download: %s\n", url)
+			continue
+		}
+
 		wg.Add(1)
 		sem <- struct{}{} // Занимаем слот
 
@@ -87,11 +101,36 @@ func main() {
 			} else {
 				fmt.Printf("Downloaded %s -> %s\n", url, filename)
 			}
-		}(i, url)
+		}(idx, url)
 	}
 
 	wg.Wait()
-	fmt.Printf("\nDownloaded %d images in %v\n", len(urls), time.Since(start))
+
+	if err := scanner.Err(); err != nil {
+		fmt.Printf("Error: invalid input: %v\n", err)
+		fmt.Printf("\nDownloaded %d images in %v\n", idx, time.Since(start))
+		os.Exit(1)
+	}
+
+	fmt.Printf("\nDownloaded %d images in %v\n", idx, time.Since(start))
+}
+
+func createLineScanner(inputFile string) (*bufio.Scanner, io.Closer, error) {
+	if inputFile == "-" {
+		return bufio.NewScanner(os.Stdin), io.NopCloser(nil), nil
+	}
+
+	file, err := os.Open(inputFile)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return bufio.NewScanner(file), file, nil
+}
+
+func isValidUrl(candidate string) bool {
+	_, err := url.ParseRequestURI(candidate)
+	return err == nil
 }
 
 // Определяем расширение файла по Content-Type