package agate

import (
	"context"
	"os"
	"path/filepath"
	"testing"
	"time"
)

// TestFullWorkflow tests a complete workflow of creating snapshots, modifying files,
// creating more snapshots, and restoring snapshots.
func TestFullWorkflow(t *testing.T) {
	// Create a temporary directory for tests
	tempDir, err := os.MkdirTemp("", "agate-test-*")
	if err != nil {
		t.Fatalf("Failed to create temp directory: %v", err)
	}
	defer os.RemoveAll(tempDir)

	// Create Agate options
	options := AgateOptions{
		WorkDir: tempDir,
	}

	// Create Agate instance
	ag, err := New(options)
	if err != nil {
		t.Fatalf("Failed to create Agate instance: %v", err)
	}
	defer ag.Close()

	// Create a data directory
	dataDir := ag.options.BlobStore.GetActiveDir()
	if err := os.MkdirAll(dataDir, 0755); err != nil {
		t.Fatalf("Failed to create data directory: %v", err)
	}

	// Create initial test files
	initialFiles := map[string]string{
		filepath.Join(dataDir, "file1.txt"):           "Initial content of file 1",
		filepath.Join(dataDir, "file2.txt"):           "Initial content of file 2",
		filepath.Join(dataDir, "subdir", "file3.txt"): "Initial content of file 3",
	}

	// Create subdirectory
	if err := os.MkdirAll(filepath.Join(dataDir, "subdir"), 0755); err != nil {
		t.Fatalf("Failed to create subdirectory: %v", err)
	}

	// Create the files
	for path, content := range initialFiles {
		if err := os.WriteFile(path, []byte(content), 0644); err != nil {
			t.Fatalf("Failed to create test file %s: %v", path, err)
		}
	}

	// Step 1: Create the first snapshot
	ctx := context.Background()
	snapshot1ID, err := ag.SaveSnapshot(ctx, "Snapshot 1", "")
	if err != nil {
		t.Fatalf("Failed to create first snapshot: %v", err)
	}
	t.Logf("Created first snapshot with ID: %s", snapshot1ID)

	// Step 2: Modify some files and add a new file
	modifiedFiles := map[string]string{
		filepath.Join(dataDir, "file1.txt"): "Modified content of file 1",
		filepath.Join(dataDir, "file4.txt"): "Content of new file 4",
	}

	for path, content := range modifiedFiles {
		if err := os.WriteFile(path, []byte(content), 0644); err != nil {
			t.Fatalf("Failed to modify/create test file %s: %v", path, err)
		}
	}

	// Step 3: Create the second snapshot
	snapshot2ID, err := ag.SaveSnapshot(ctx, "Snapshot 2", snapshot1ID)
	if err != nil {
		t.Fatalf("Failed to create second snapshot: %v", err)
	}
	t.Logf("Created second snapshot with ID: %s", snapshot2ID)

	// Step 4: Delete a file and modify another
	if err := os.Remove(filepath.Join(dataDir, "file2.txt")); err != nil {
		t.Fatalf("Failed to delete test file: %v", err)
	}

	if err := os.WriteFile(filepath.Join(dataDir, "subdir/file3.txt"), []byte("Modified content of file 3"), 0644); err != nil {
		t.Fatalf("Failed to modify test file: %v", err)
	}

	// Step 5: Create the third snapshot
	snapshot3ID, err := ag.SaveSnapshot(ctx, "Snapshot 3", snapshot2ID)
	if err != nil {
		t.Fatalf("Failed to create third snapshot: %v", err)
	}
	t.Logf("Created third snapshot with ID: %s", snapshot3ID)

	// Step 6: List all snapshots
	snapshots, err := ag.ListSnapshots(ctx)
	if err != nil {
		t.Fatalf("Failed to list snapshots: %v", err)
	}

	if len(snapshots) != 3 {
		t.Errorf("Expected 3 snapshots, got %d", len(snapshots))
	}

	// Step 7: Restore the first snapshot
	err = ag.RestoreSnapshot(ctx, snapshot1ID)
	if err != nil {
		t.Fatalf("Failed to restore first snapshot: %v", err)
	}
	t.Logf("Restored first snapshot")

	// Step 8: Verify the restored files match the initial state
	for path, expectedContent := range initialFiles {
		content, err := os.ReadFile(path)
		if err != nil {
			t.Fatalf("Failed to read restored file %s: %v", path, err)
		}
		if string(content) != expectedContent {
			t.Errorf("Restored file %s has wrong content: got %s, want %s", path, string(content), expectedContent)
		}
	}

	// Check that file4.txt doesn't exist
	if _, err := os.Stat(filepath.Join(dataDir, "file4.txt")); !os.IsNotExist(err) {
		t.Errorf("File4.txt should not exist after restoring first snapshot")
	}

	// Step 9: Restore the third snapshot
	err = ag.RestoreSnapshot(ctx, snapshot3ID)
	if err != nil {
		t.Fatalf("Failed to restore third snapshot: %v", err)
	}
	t.Logf("Restored third snapshot")

	// Step 10: Verify the restored files match the final state
	expectedFiles := map[string]string{
		filepath.Join(dataDir, "file1.txt"):        "Modified content of file 1",
		filepath.Join(dataDir, "file4.txt"):        "Content of new file 4",
		filepath.Join(dataDir, "subdir/file3.txt"): "Modified content of file 3",
	}

	for path, expectedContent := range expectedFiles {
		content, err := os.ReadFile(path)
		if err != nil {
			t.Fatalf("Failed to read restored file %s: %v", path, err)
		}
		if string(content) != expectedContent {
			t.Errorf("Restored file %s has wrong content: got %s, want %s", path, string(content), expectedContent)
		}
	}

	// Check that file2.txt doesn't exist
	if _, err := os.Stat(filepath.Join(dataDir, "file2.txt")); !os.IsNotExist(err) {
		t.Errorf("File2.txt should not exist after restoring third snapshot")
	}

	// Step 11: Delete a snapshot
	err = ag.DeleteSnapshot(ctx, snapshot2ID)
	if err != nil {
		t.Fatalf("Failed to delete snapshot: %v", err)
	}
	t.Logf("Deleted second snapshot")

	// Step 12: Verify the snapshot was deleted
	snapshots, err = ag.ListSnapshots(ctx)
	if err != nil {
		t.Fatalf("Failed to list snapshots: %v", err)
	}

	if len(snapshots) != 2 {
		t.Errorf("Expected 2 snapshots after deletion, got %d", len(snapshots))
	}

	for _, snap := range snapshots {
		if snap.ID == snapshot2ID {
			t.Errorf("Snapshot 2 should have been deleted")
		}
	}
}

// TestLargeFiles tests creating and restoring snapshots with large files
func TestLargeFiles(t *testing.T) {
	// Skip this test in short mode
	if testing.Short() {
		t.Skip("Skipping large file test in short mode")
	}

	// Create a temporary directory for tests
	tempDir, err := os.MkdirTemp("", "agate-test-*")
	if err != nil {
		t.Fatalf("Failed to create temp directory: %v", err)
	}
	defer os.RemoveAll(tempDir)

	// Create Agate options
	options := AgateOptions{
		WorkDir: tempDir,
		OpenFunc: func(dir string) error {
			return nil
		},
		CloseFunc: func() error {
			return nil
		},
	}

	// Create Agate instance
	ag, err := New(options)
	if err != nil {
		t.Fatalf("Failed to create Agate instance: %v", err)
	}
	defer ag.Close()

	// Create a data directory
	dataDir := ag.options.BlobStore.GetActiveDir()
	if err := os.MkdirAll(dataDir, 0755); err != nil {
		t.Fatalf("Failed to create data directory: %v", err)
	}

	// Create a large file (10 MB)
	largeFilePath := filepath.Join(dataDir, "large_file.bin")
	largeFileSize := 10 * 1024 * 1024 // 10 MB
	largeFile, err := os.Create(largeFilePath)
	if err != nil {
		t.Fatalf("Failed to create large test file: %v", err)
	}

	// Fill the file with a repeating pattern
	pattern := []byte("0123456789ABCDEF")
	buffer := make([]byte, 8192) // 8 KB buffer
	for i := 0; i < len(buffer); i += len(pattern) {
		copy(buffer[i:], pattern)
	}

	// Write the buffer multiple times to reach the desired size
	bytesWritten := 0
	for bytesWritten < largeFileSize {
		n, err := largeFile.Write(buffer)
		if err != nil {
			largeFile.Close()
			t.Fatalf("Failed to write to large test file: %v", err)
		}
		bytesWritten += n
	}
	largeFile.Close()

	// Create a snapshot
	ctx := context.Background()
	startTime := time.Now()
	snapshotID, err := ag.SaveSnapshot(ctx, "Large File Snapshot", "")
	if err != nil {
		t.Fatalf("Failed to create snapshot: %v", err)
	}
	duration := time.Since(startTime)
	t.Logf("Created snapshot with large file in %v", duration)

	// Modify the large file
	if err := os.WriteFile(largeFilePath, []byte("Modified content"), 0644); err != nil {
		t.Fatalf("Failed to modify large file: %v", err)
	}

	// Restore the snapshot
	startTime = time.Now()
	err = ag.RestoreSnapshot(ctx, snapshotID)
	if err != nil {
		t.Fatalf("Failed to restore snapshot: %v", err)
	}
	duration = time.Since(startTime)
	t.Logf("Restored snapshot with large file in %v", duration)

	// Verify the file size is correct
	fileInfo, err := os.Stat(largeFilePath)
	if err != nil {
		t.Fatalf("Failed to stat restored large file: %v", err)
	}
	if fileInfo.Size() != int64(largeFileSize) {
		t.Errorf("Restored large file has wrong size: got %d, want %d", fileInfo.Size(), largeFileSize)
	}
}