package main

import (
	"crypto/rand"
	"encoding/base64"
	"io"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func TestDecryptMediaFileRoundTrip(t *testing.T) {
	dir := t.TempDir()
	encPath := filepath.Join(dir, "movie.enc")

	// 1. Generate key and encrypt data
	key := make([]byte, 32)
	if _, err := rand.Read(key); err != nil {
		t.Fatal(err)
	}
	keyB64 := base64.StdEncoding.EncodeToString(key)

	plainData := []byte("hello world video bytes 1234567890")
	encFile, err := os.Create(encPath)
	if err != nil {
		t.Fatal(err)
	}

	// Write magic
	if _, err := io.WriteString(encFile, mediaLockMagic); err != nil {
		encFile.Close()
		t.Fatal(err)
	}

	// XOR encrypt
	ki := 0
	encData := make([]byte, len(plainData))
	for i := 0; i < len(plainData); i++ {
		encData[i] = plainData[i] ^ key[ki%len(key)]
		ki++
	}
	if _, err := encFile.Write(encData); err != nil {
		encFile.Close()
		t.Fatal(err)
	}
	encFile.Close()

	// 2. Decrypt media file
	decPath, cleanup, err := decryptMediaFile(encPath, keyB64, "decrypted.mp4")
	if err != nil {
		t.Fatalf("decryptMediaFile failed: %v", err)
	}
	defer cleanup()

	// 3. Verify content
	decData, err := os.ReadFile(decPath)
	if err != nil {
		t.Fatal(err)
	}

	if string(decData) != string(plainData) {
		t.Fatalf("decrypted data mismatch: got %q, want %q", string(decData), string(plainData))
	}
}

func TestDecryptMediaFileInvalidKey(t *testing.T) {
	dir := t.TempDir()
	encPath := filepath.Join(dir, "movie.enc")
	if err := os.WriteFile(encPath, []byte("whatever"), 0644); err != nil {
		t.Fatal(err)
	}

	// Test invalid base64 key
	_, _, err := decryptMediaFile(encPath, "!!!invalid-b64!!!", "decrypted.mp4")
	if err == nil || !strings.Contains(err.Error(), "invalid media key") {
		t.Fatalf("expected invalid media key error, got %v", err)
	}
}

func TestDecryptMediaFileInvalidMagic(t *testing.T) {
	dir := t.TempDir()
	encPath := filepath.Join(dir, "movie.enc")
	if err := os.WriteFile(encPath, []byte("NOT_MAGIC_12345"), 0644); err != nil {
		t.Fatal(err)
	}

	key := make([]byte, 32)
	keyB64 := base64.StdEncoding.EncodeToString(key)

	_, _, err := decryptMediaFile(encPath, keyB64, "decrypted.mp4")
	if err == nil || !strings.Contains(err.Error(), "not a locked media file") {
		t.Fatalf("expected invalid magic error, got %v", err)
	}
}