package starssh

import (
	"context"
	"errors"
	"io"
	"net"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/pkg/sftp"
)

func TestNormalizeSFTPTransferOptionsDefaultsAtomicDownload(t *testing.T) {
	opts := normalizeSFTPTransferOptions(nil)
	if !opts.AtomicUpload {
		t.Fatal("expected atomic upload to default to enabled")
	}
	if !opts.AtomicDownload {
		t.Fatal("expected atomic download to default to enabled")
	}
}

func TestTransferOutContextVerifyFailurePreservesRemoteTarget(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	localPath := filepath.Join(root, "local.txt")
	remotePath := filepath.Join(root, "remote.txt")

	if err := os.WriteFile(localPath, []byte("new payload"), 0o644); err != nil {
		t.Fatalf("write local file: %v", err)
	}
	if err := os.WriteFile(remotePath, []byte("original remote"), 0o644); err != nil {
		t.Fatalf("write remote file: %v", err)
	}

	verifyErr := errors.New("verify failed")
	var verifiedPath string
	oldVerifyRemoteSize := sftpVerifyRemoteSizeFunc
	sftpVerifyRemoteSizeFunc = func(client *sftp.Client, remotePath string, expected int64) error {
		verifiedPath = remotePath
		return verifyErr
	}
	t.Cleanup(func() {
		sftpVerifyRemoteSizeFunc = oldVerifyRemoteSize
	})

	err := transferOutContext(context.Background(), client, localPath, remotePath, normalizeSFTPTransferOptions(nil))
	if !errors.Is(err, verifyErr) {
		t.Fatalf("expected verify failure, got %v", err)
	}
	if verifiedPath == remotePath {
		t.Fatal("expected upload verification to run against temp path before final rename")
	}

	data, err := os.ReadFile(remotePath)
	if err != nil {
		t.Fatalf("read remote file: %v", err)
	}
	if string(data) != "original remote" {
		t.Fatalf("remote target was replaced on verify failure: %q", string(data))
	}
	assertNoTransferTemps(t, remotePath)
}

func TestTransferOutContextRejectsRemoteSymlinkTarget(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	localPath := filepath.Join(root, "local.txt")
	remoteRealPath := filepath.Join(root, "remote-real.txt")
	remotePath := filepath.Join(root, "remote-link.txt")

	if err := os.WriteFile(localPath, []byte("new payload"), 0o644); err != nil {
		t.Fatalf("write local file: %v", err)
	}
	if err := os.WriteFile(remoteRealPath, []byte("original remote"), 0o644); err != nil {
		t.Fatalf("write remote backing file: %v", err)
	}
	if err := os.Symlink(remoteRealPath, remotePath); err != nil {
		t.Skipf("symlink unsupported: %v", err)
	}

	err := transferOutContext(context.Background(), client, localPath, remotePath, normalizeSFTPTransferOptions(nil))
	if err == nil || !strings.Contains(err.Error(), "symlink") {
		t.Fatalf("expected symlink rejection, got %v", err)
	}

	info, err := os.Lstat(remotePath)
	if err != nil {
		t.Fatalf("lstat remote symlink: %v", err)
	}
	if info.Mode()&os.ModeSymlink == 0 {
		t.Fatal("expected remote target to remain a symlink")
	}

	data, err := os.ReadFile(remoteRealPath)
	if err != nil {
		t.Fatalf("read remote backing file: %v", err)
	}
	if string(data) != "original remote" {
		t.Fatalf("remote backing file changed unexpectedly: %q", string(data))
	}
	assertNoTransferTemps(t, remotePath)
}

func TestTransferOutContextRejectsRemoteDirectoryTarget(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	localPath := filepath.Join(root, "local.txt")
	remotePath := filepath.Join(root, "remote-dir")

	if err := os.WriteFile(localPath, []byte("new payload"), 0o644); err != nil {
		t.Fatalf("write local file: %v", err)
	}
	if err := os.Mkdir(remotePath, 0o755); err != nil {
		t.Fatalf("mkdir remote target: %v", err)
	}

	err := transferOutContext(context.Background(), client, localPath, remotePath, normalizeSFTPTransferOptions(nil))
	if err == nil || !strings.Contains(err.Error(), "directory") {
		t.Fatalf("expected directory rejection, got %v", err)
	}

	info, err := os.Stat(remotePath)
	if err != nil {
		t.Fatalf("stat remote directory: %v", err)
	}
	if !info.IsDir() {
		t.Fatal("expected remote target to remain a directory")
	}
	assertNoTransferTemps(t, remotePath)
}

func TestTransferOutContextPreservesRemoteModeOnOverwrite(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	localPath := filepath.Join(root, "local.txt")
	remotePath := filepath.Join(root, "remote.txt")

	if err := os.WriteFile(localPath, []byte("new payload"), 0o644); err != nil {
		t.Fatalf("write local file: %v", err)
	}
	if err := os.WriteFile(remotePath, []byte("original remote"), 0o755); err != nil {
		t.Fatalf("write remote file: %v", err)
	}
	if err := os.Chmod(remotePath, 0o755); err != nil {
		t.Fatalf("chmod remote file: %v", err)
	}

	if err := transferOutContext(context.Background(), client, localPath, remotePath, normalizeSFTPTransferOptions(nil)); err != nil {
		t.Fatalf("transfer out: %v", err)
	}

	assertMode(t, remotePath, 0o755)
	assertFileContent(t, remotePath, "new payload")
}

func TestTransferOutContextAppliesLocalModeForNewRemoteFile(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	localPath := filepath.Join(root, "local.txt")
	remotePath := filepath.Join(root, "remote.txt")

	if err := os.WriteFile(localPath, []byte("new payload"), 0o751); err != nil {
		t.Fatalf("write local file: %v", err)
	}
	if err := os.Chmod(localPath, 0o751); err != nil {
		t.Fatalf("chmod local file: %v", err)
	}

	if err := transferOutContext(context.Background(), client, localPath, remotePath, normalizeSFTPTransferOptions(nil)); err != nil {
		t.Fatalf("transfer out: %v", err)
	}

	assertMode(t, remotePath, 0o751)
	assertFileContent(t, remotePath, "new payload")
}

func TestTransferOutByteContextPreservesRemoteModeOnOverwrite(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	remotePath := filepath.Join(root, "remote.txt")

	if err := os.WriteFile(remotePath, []byte("original remote"), 0o755); err != nil {
		t.Fatalf("write remote file: %v", err)
	}
	if err := os.Chmod(remotePath, 0o755); err != nil {
		t.Fatalf("chmod remote file: %v", err)
	}

	if err := transferOutByteContext(context.Background(), client, []byte("byte payload"), remotePath, normalizeSFTPTransferOptions(nil)); err != nil {
		t.Fatalf("transfer out bytes: %v", err)
	}

	assertMode(t, remotePath, 0o755)
	assertFileContent(t, remotePath, "byte payload")
}

func TestTransferInContextVerifyFailurePreservesLocalTarget(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	srcPath := filepath.Join(root, "remote.txt")
	dstPath := filepath.Join(root, "local.txt")

	if err := os.WriteFile(srcPath, []byte("fresh remote payload"), 0o644); err != nil {
		t.Fatalf("write remote file: %v", err)
	}
	if err := os.WriteFile(dstPath, []byte("original local"), 0o644); err != nil {
		t.Fatalf("write local file: %v", err)
	}

	verifyErr := errors.New("verify local failed")
	var verifiedPath string
	oldVerifyLocalSize := sftpVerifyLocalSizeFunc
	sftpVerifyLocalSizeFunc = func(localPath string, expected int64) error {
		verifiedPath = localPath
		return verifyErr
	}
	t.Cleanup(func() {
		sftpVerifyLocalSizeFunc = oldVerifyLocalSize
	})

	err := transferInContext(context.Background(), client, srcPath, dstPath, normalizeSFTPTransferOptions(nil))
	if !errors.Is(err, verifyErr) {
		t.Fatalf("expected verify failure, got %v", err)
	}
	if verifiedPath == dstPath {
		t.Fatal("expected download verification to run against temp path before final rename")
	}

	data, err := os.ReadFile(dstPath)
	if err != nil {
		t.Fatalf("read local file: %v", err)
	}
	if string(data) != "original local" {
		t.Fatalf("local target was replaced on verify failure: %q", string(data))
	}
	assertNoTransferTemps(t, dstPath)
}

func TestTransferInContextRejectsLocalSymlinkTarget(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	srcPath := filepath.Join(root, "remote.txt")
	localRealPath := filepath.Join(root, "local-real.txt")
	dstPath := filepath.Join(root, "local-link.txt")

	if err := os.WriteFile(srcPath, []byte("fresh remote payload"), 0o644); err != nil {
		t.Fatalf("write remote file: %v", err)
	}
	if err := os.WriteFile(localRealPath, []byte("original local"), 0o644); err != nil {
		t.Fatalf("write local backing file: %v", err)
	}
	if err := os.Symlink(localRealPath, dstPath); err != nil {
		t.Skipf("symlink unsupported: %v", err)
	}

	err := transferInContext(context.Background(), client, srcPath, dstPath, normalizeSFTPTransferOptions(nil))
	if err == nil || !strings.Contains(err.Error(), "symlink") {
		t.Fatalf("expected symlink rejection, got %v", err)
	}

	info, err := os.Lstat(dstPath)
	if err != nil {
		t.Fatalf("lstat local symlink: %v", err)
	}
	if info.Mode()&os.ModeSymlink == 0 {
		t.Fatal("expected local target to remain a symlink")
	}
	assertFileContent(t, localRealPath, "original local")
	assertNoTransferTemps(t, dstPath)
}

func TestTransferInContextRejectsLocalDirectoryTarget(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	srcPath := filepath.Join(root, "remote.txt")
	dstPath := filepath.Join(root, "local-dir")

	if err := os.WriteFile(srcPath, []byte("fresh remote payload"), 0o644); err != nil {
		t.Fatalf("write remote file: %v", err)
	}
	if err := os.Mkdir(dstPath, 0o755); err != nil {
		t.Fatalf("mkdir local target: %v", err)
	}

	err := transferInContext(context.Background(), client, srcPath, dstPath, normalizeSFTPTransferOptions(nil))
	if err == nil || !strings.Contains(err.Error(), "directory") {
		t.Fatalf("expected directory rejection, got %v", err)
	}

	info, err := os.Stat(dstPath)
	if err != nil {
		t.Fatalf("stat local directory: %v", err)
	}
	if !info.IsDir() {
		t.Fatal("expected local target to remain a directory")
	}
	assertNoTransferTemps(t, dstPath)
}

func TestTransferInContextPreservesLocalModeOnOverwrite(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	srcPath := filepath.Join(root, "remote.txt")
	dstPath := filepath.Join(root, "local.sh")

	if err := os.WriteFile(srcPath, []byte("#!/bin/sh\necho remote\n"), 0o644); err != nil {
		t.Fatalf("write remote file: %v", err)
	}
	if err := os.WriteFile(dstPath, []byte("#!/bin/sh\necho local\n"), 0o755); err != nil {
		t.Fatalf("write local file: %v", err)
	}
	if err := os.Chmod(dstPath, 0o755); err != nil {
		t.Fatalf("chmod local file: %v", err)
	}

	if err := transferInContext(context.Background(), client, srcPath, dstPath, normalizeSFTPTransferOptions(nil)); err != nil {
		t.Fatalf("transfer in: %v", err)
	}

	assertMode(t, dstPath, 0o755)
	assertFileContent(t, dstPath, "#!/bin/sh\necho remote\n")
}

func TestTransferInContextAppliesRemoteModeForNewLocalFile(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	srcPath := filepath.Join(root, "remote.sh")
	dstPath := filepath.Join(root, "local.sh")

	if err := os.WriteFile(srcPath, []byte("#!/bin/sh\necho remote\n"), 0o751); err != nil {
		t.Fatalf("write remote file: %v", err)
	}
	if err := os.Chmod(srcPath, 0o751); err != nil {
		t.Fatalf("chmod remote file: %v", err)
	}

	if err := transferInContext(context.Background(), client, srcPath, dstPath, normalizeSFTPTransferOptions(nil)); err != nil {
		t.Fatalf("transfer in: %v", err)
	}

	assertMode(t, dstPath, 0o751)
	assertFileContent(t, dstPath, "#!/bin/sh\necho remote\n")
}

func TestTransferInContextCopyFailurePreservesLocalTarget(t *testing.T) {
	client := newSFTPTestClient(t)
	root := t.TempDir()
	srcPath := filepath.Join(root, "remote.txt")
	dstPath := filepath.Join(root, "local.txt")

	if err := os.WriteFile(srcPath, []byte("fresh remote payload"), 0o644); err != nil {
		t.Fatalf("write remote file: %v", err)
	}
	if err := os.WriteFile(dstPath, []byte("original local"), 0o644); err != nil {
		t.Fatalf("write local file: %v", err)
	}

	copyErr := errors.New("copy failed")
	var copyTargetPath string
	oldCopy := sftpCopyWithProgressFunc
	sftpCopyWithProgressFunc = func(ctx context.Context, dst io.Writer, src io.Reader, bufSize int, total int64, progress func(float64)) (int64, error) {
		file, ok := dst.(*os.File)
		if !ok {
			t.Fatalf("expected local temp file writer, got %T", dst)
		}
		copyTargetPath = file.Name()

		buf := make([]byte, 8)
		n, readErr := src.Read(buf)
		if readErr != nil && !errors.Is(readErr, io.EOF) {
			return 0, readErr
		}
		if n > 0 {
			written, err := dst.Write(buf[:n])
			if err != nil {
				return int64(written), err
			}
			return int64(written), copyErr
		}
		return 0, copyErr
	}
	t.Cleanup(func() {
		sftpCopyWithProgressFunc = oldCopy
	})

	err := transferInContext(context.Background(), client, srcPath, dstPath, normalizeSFTPTransferOptions(nil))
	if !errors.Is(err, copyErr) {
		t.Fatalf("expected copy failure, got %v", err)
	}
	if copyTargetPath == dstPath {
		t.Fatal("expected partial download writes to stay on temp path")
	}

	data, err := os.ReadFile(dstPath)
	if err != nil {
		t.Fatalf("read local file: %v", err)
	}
	if string(data) != "original local" {
		t.Fatalf("local target was modified by partial download: %q", string(data))
	}
	assertNoTransferTemps(t, dstPath)
}

func newSFTPTestClient(t *testing.T) *sftp.Client {
	t.Helper()

	serverConn, clientConn := net.Pipe()
	server, err := sftp.NewServer(serverConn)
	if err != nil {
		t.Fatalf("create sftp server: %v", err)
	}

	serveErrCh := make(chan error, 1)
	go func() {
		serveErrCh <- server.Serve()
	}()

	client, err := sftp.NewClientPipe(clientConn, clientConn)
	if err != nil {
		_ = server.Close()
		t.Fatalf("create sftp client: %v", err)
	}

	t.Cleanup(func() {
		_ = client.Close()
		_ = server.Close()
		serveErr := <-serveErrCh
		if serveErr == nil || errors.Is(serveErr, io.EOF) || normalizeAlreadyClosedError(serveErr) == nil {
			return
		}
		t.Errorf("unexpected sftp server error: %v", serveErr)
	})

	return client
}

func assertNoTransferTemps(t *testing.T, targetPath string) {
	t.Helper()

	matches, err := filepath.Glob(targetPath + defaultSFTPTempSuffix + "*")
	if err != nil {
		t.Fatalf("glob temp files: %v", err)
	}
	if len(matches) != 0 {
		t.Fatalf("expected temp artifacts to be cleaned up, got %v", matches)
	}
}

func assertMode(t *testing.T, targetPath string, want os.FileMode) {
	t.Helper()

	info, err := os.Stat(targetPath)
	if err != nil {
		t.Fatalf("stat %q: %v", targetPath, err)
	}
	if got := info.Mode().Perm(); got != want {
		t.Fatalf("unexpected mode for %q: got %o want %o", targetPath, got, want)
	}
}

func assertFileContent(t *testing.T, targetPath string, want string) {
	t.Helper()

	data, err := os.ReadFile(targetPath)
	if err != nil {
		t.Fatalf("read %q: %v", targetPath, err)
	}
	if string(data) != want {
		t.Fatalf("unexpected content for %q: got %q want %q", targetPath, string(data), want)
	}
}