feat: add proxy rotation functionality

internal/proxyrotator/proxyrotator.go

@@ -0,0 +1,60 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package proxyrotator // import "miniflux.app/v2/internal/proxyrotator"
+
+import (
+	"net/url"
+	"sync"
+)
+
+var ProxyRotatorInstance *ProxyRotator
+
+// ProxyRotator manages a list of proxies and rotates through them.
+type ProxyRotator struct {
+	proxies      []*url.URL
+	currentIndex int
+	mutex        sync.Mutex
+}
+
+// NewProxyRotator creates a new ProxyRotator with the given proxy URLs.
+func NewProxyRotator(proxyURLs []string) (*ProxyRotator, error) {
+	parsedProxies := make([]*url.URL, 0, len(proxyURLs))
+
+	for _, p := range proxyURLs {
+		proxyURL, err := url.Parse(p)
+		if err != nil {
+			return nil, err
+		}
+		parsedProxies = append(parsedProxies, proxyURL)
+	}
+
+	return &ProxyRotator{
+		proxies:      parsedProxies,
+		currentIndex: 0,
+		mutex:        sync.Mutex{},
+	}, nil
+}
+
+// GetNextProxy returns the next proxy in the rotation.
+func (pr *ProxyRotator) GetNextProxy() *url.URL {
+	pr.mutex.Lock()
+	defer pr.mutex.Unlock()
+
+	if len(pr.proxies) == 0 {
+		return nil
+	}
+
+	proxy := pr.proxies[pr.currentIndex]
+	pr.currentIndex = (pr.currentIndex + 1) % len(pr.proxies)
+
+	return proxy
+}
+
+// HasProxies checks if there are any proxies available in the rotator.
+func (pr *ProxyRotator) HasProxies() bool {
+	pr.mutex.Lock()
+	defer pr.mutex.Unlock()
+
+	return len(pr.proxies) > 0
+}

internal/proxyrotator/proxyrotator_test.go

@@ -0,0 +1,71 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package proxyrotator // import "miniflux.app/v2/internal/proxyrotator"
+
+import (
+	"testing"
+)
+
+func TestProxyRotator(t *testing.T) {
+	proxyURLs := []string{
+		"http://proxy1.example.com",
+		"http://proxy2.example.com",
+		"http://proxy3.example.com",
+	}
+
+	rotator, err := NewProxyRotator(proxyURLs)
+	if err != nil {
+		t.Fatalf("Failed to create ProxyRotator: %v", err)
+	}
+
+	if !rotator.HasProxies() {
+		t.Fatalf("Expected rotator to have proxies")
+	}
+
+	seenProxies := make(map[string]bool)
+	for range len(proxyURLs) * 2 {
+		proxy := rotator.GetNextProxy()
+		if proxy == nil {
+			t.Fatalf("Expected a proxy, got nil")
+		}
+
+		seenProxies[proxy.String()] = true
+	}
+
+	if len(seenProxies) != len(proxyURLs) {
+		t.Fatalf("Expected to see all proxies, but saw: %v", seenProxies)
+	}
+}
+
+func TestProxyRotatorEmpty(t *testing.T) {
+	rotator, err := NewProxyRotator([]string{})
+	if err != nil {
+		t.Fatalf("Failed to create ProxyRotator: %v", err)
+	}
+
+	if rotator.HasProxies() {
+		t.Fatalf("Expected rotator to have no proxies")
+	}
+
+	proxy := rotator.GetNextProxy()
+	if proxy != nil {
+		t.Fatalf("Expected no proxy, got: %v", proxy)
+	}
+}
+
+func TestProxyRotatorInvalidURL(t *testing.T) {
+	invalidProxyURLs := []string{
+		"http://validproxy.example.com",
+		"test|test://invalidproxy.example.com",
+	}
+
+	rotator, err := NewProxyRotator(invalidProxyURLs)
+	if err == nil {
+		t.Fatalf("Expected an error when creating ProxyRotator with invalid URLs, but got none")
+	}
+
+	if rotator != nil {
+		t.Fatalf("Expected rotator to be nil when initialization fails, but got: %v", rotator)
+	}
+}