// steamcache/steamcache_test.go
package steamcache

import (
	"io"
	"net/http"
	"os"
	"path/filepath"
	"testing"
)

func TestCaching(t *testing.T) {
	td := t.TempDir()

	os.WriteFile(filepath.Join(td, "key2"), []byte("value2"), 0644)

	sc := New("localhost:8080", "1G", "1G", td, "", "lru", "lru")

	w, err := sc.vfs.Create("key", 5)
	if err != nil {
		t.Errorf("Create failed: %v", err)
	}
	w.Write([]byte("value"))
	w.Close()

	w, err = sc.vfs.Create("key1", 6)
	if err != nil {
		t.Errorf("Create failed: %v", err)
	}
	w.Write([]byte("value1"))
	w.Close()

	if sc.diskgc.Size() != 17 {
		t.Errorf("Size failed: got %d, want %d", sc.diskgc.Size(), 17)
	}

	if sc.vfs.Size() != 17 {
		t.Errorf("Size failed: got %d, want %d", sc.vfs.Size(), 17)
	}

	rc, err := sc.vfs.Open("key")
	if err != nil {
		t.Errorf("Open failed: %v", err)
	}
	d, _ := io.ReadAll(rc)
	rc.Close()
	if string(d) != "value" {
		t.Errorf("Get failed: got %s, want %s", d, "value")
	}

	rc, err = sc.vfs.Open("key1")
	if err != nil {
		t.Errorf("Open failed: %v", err)
	}
	d, _ = io.ReadAll(rc)
	rc.Close()
	if string(d) != "value1" {
		t.Errorf("Get failed: got %s, want %s", d, "value1")
	}

	rc, err = sc.vfs.Open("key2")
	if err != nil {
		t.Errorf("Open failed: %v", err)
	}
	d, _ = io.ReadAll(rc)
	rc.Close()
	if string(d) != "value2" {
		t.Errorf("Get failed: got %s, want %s", d, "value2")
	}

	if sc.diskgc.Size() != 17 {
		t.Errorf("Size failed: got %d, want %d", sc.diskgc.Size(), 17)
	}

	if sc.vfs.Size() != 17 {
		t.Errorf("Size failed: got %d, want %d", sc.vfs.Size(), 17)
	}

	sc.memory.Delete("key2")
	os.Remove(filepath.Join(td, "key2"))

	if _, err := sc.vfs.Open("key2"); err == nil {
		t.Errorf("Open failed: got nil, want error")
	}
}

func TestCacheMissAndHit(t *testing.T) {
	sc := New("localhost:8080", "0", "1G", t.TempDir(), "", "lru", "lru")

	key := "testkey"
	value := []byte("testvalue")

	// Simulate miss: but since no upstream, skip full ServeHTTP, test VFS
	w, err := sc.vfs.Create(key, int64(len(value)))
	if err != nil {
		t.Fatal(err)
	}
	w.Write(value)
	w.Close()

	rc, err := sc.vfs.Open(key)
	if err != nil {
		t.Fatal(err)
	}
	got, _ := io.ReadAll(rc)
	rc.Close()

	if string(got) != string(value) {
		t.Errorf("expected %s, got %s", value, got)
	}
}

func TestHashCalculation(t *testing.T) {
	// Test data
	testData := []byte("Hello, World!")

	// Calculate hash
	hash := calculateFileHash(testData)

	// Expected SHA1 hash of "Hello, World!"
	expectedHash := "0a0a9f2a6772942557ab5355d76af442f8f65e01"

	if hash != expectedHash {
		t.Errorf("Hash calculation failed: expected %s, got %s", expectedHash, hash)
	}

	// Test verification
	if !verifyFileHash(testData, expectedHash) {
		t.Error("Hash verification failed for correct hash")
	}

	if verifyFileHash(testData, "wronghash") {
		t.Error("Hash verification passed for wrong hash")
	}
}

func TestHashVerificationWithRealData(t *testing.T) {
	// Test with some real data to ensure our hash calculation is correct
	testCases := []struct {
		data     string
		expected string
	}{
		{"", "da39a3ee5e6b4b0d3255bfef95601890afd80709"},              // SHA1 of empty string
		{"test", "a94a8fe5ccb19ba61c4c0873d391e987982fbbd3"},          // SHA1 of "test"
		{"Hello, World!", "0a0a9f2a6772942557ab5355d76af442f8f65e01"}, // SHA1 of "Hello, World!"
	}

	for _, tc := range testCases {
		data := []byte(tc.data)
		hash := calculateFileHash(data)
		if hash != tc.expected {
			t.Errorf("Hash calculation failed for '%s': expected %s, got %s", tc.data, tc.expected, hash)
		}

		if !verifyFileHash(data, tc.expected) {
			t.Errorf("Hash verification failed for '%s'", tc.data)
		}
	}
}

func TestResponseHashCalculation(t *testing.T) {
	// Create a mock HTTP response
	resp := &http.Response{
		StatusCode: 200,
		Status:     "200 OK",
		Header: http.Header{
			"Content-Type":   []string{"application/octet-stream"},
			"Content-Length": []string{"13"},
			"Cache-Control":  []string{"public, max-age=3600"},
		},
	}

	bodyData := []byte("Hello, World!")

	// Calculate response hash
	responseHash := calculateResponseHash(resp, bodyData)

	// The hash should be different from just the body hash
	bodyHash := calculateFileHash(bodyData)

	if responseHash == bodyHash {
		t.Error("Response hash should be different from body hash when headers are present")
	}

	// Test that the same response produces the same hash
	responseHash2 := calculateResponseHash(resp, bodyData)
	if responseHash != responseHash2 {
		t.Error("Response hash should be consistent for the same response")
	}

	// Test with different headers
	resp2 := &http.Response{
		StatusCode: 200,
		Status:     "200 OK",
		Header: http.Header{
			"Content-Type":   []string{"text/plain"},
			"Content-Length": []string{"13"},
		},
	}

	responseHash3 := calculateResponseHash(resp2, bodyData)
	if responseHash == responseHash3 {
		t.Error("Response hash should be different for different headers")
	}
}

func TestSteamKeySharding(t *testing.T) {
	sc := New("localhost:8080", "0", "1G", t.TempDir(), "", "lru", "lru")

	// Test with a Steam-style key that should trigger sharding
	steamKey := "steam/0016cfc5019b8baa6026aa1cce93e685d6e06c6e"
	testData := []byte("test steam cache data")

	// Create a file with the steam key
	w, err := sc.vfs.Create(steamKey, int64(len(testData)))
	if err != nil {
		t.Fatalf("Failed to create file with steam key: %v", err)
	}
	w.Write(testData)
	w.Close()

	// Verify we can read it back
	rc, err := sc.vfs.Open(steamKey)
	if err != nil {
		t.Fatalf("Failed to open file with steam key: %v", err)
	}
	got, _ := io.ReadAll(rc)
	rc.Close()

	if string(got) != string(testData) {
		t.Errorf("Data mismatch: expected %s, got %s", testData, got)
	}

	// Verify that the file was created (sharding is working if no error occurred)
	// The key difference is that with sharding, the file should be created successfully
	// and be readable, whereas without sharding it might not work correctly
}

func TestKeyGeneration(t *testing.T) {
	testCases := []struct {
		input    string
		expected string
		desc     string
	}{
		{
			input:    "/depot/1684171/chunk/0016cfc5019b8baa6026aa1cce93e685d6e06c6e",
			expected: "steam/0016cfc5019b8baa6026aa1cce93e685d6e06c6e",
			desc:     "chunk file URL",
		},
		{
			input:    "/depot/1684171/manifest/944076726177422892/5/12001286503415372840",
			expected: "steam/12001286503415372840",
			desc:     "manifest file URL",
		},
		{
			input:    "/depot/invalid/path",
			expected: "",
			desc:     "invalid depot URL format",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.desc, func(t *testing.T) {
			result := generateSteamCacheKey(tc.input)
			if result != tc.expected {
				t.Errorf("generateSteamCacheKey(%s) = %s, expected %s", tc.input, result, tc.expected)
			}
		})
	}
}