// capture_ftp.go — application-level FTP/SFTP upload orchestration.
//
// Design rationale:
//   - FTP/SFTP returns a remote filesystem path, not necessarily a public URL,
//     so this flow stays separate from the OSSProvider-based S3 pipeline.
//   - A tiny uploader interface keeps protocol libraries out of the
//     application layer and makes the upload/copy/notify sequence unit-testable.
//   - The dated filename layout is shared with SSH/SCP while FTP-specific path
//     validation prevents an invalid prefix from escaping the login root.
package application

import (
	"context"
	"fmt"
	"log/slog"
	"strings"
	"time"

	"github.com/mmmy/snapgo/internal/domain"
	"github.com/mmmy/snapgo/internal/infrastructure/clipboard"
)

// ftpSvcLog returns an application-layer FTP logger bound to the current
// default slog handler.
func ftpSvcLog() *slog.Logger { return slog.Default().With("component", "application.ftp") }

// FTPUploader abstracts both FTP and SFTP adapters.
type FTPUploader interface {
	// Upload stores data at remoteRelPath, relative to the authenticated
	// account's login root.
	Upload(ctx context.Context, remoteRelPath string, data []byte) error
}

// CaptureAndFTPService wires captured PNG bytes → FTP/SFTP → clipboard →
// notification.
type CaptureAndFTPService struct {
	Uploader  FTPUploader
	Clipboard clipboard.Writer
	Notifier  Notifier
	Cfg       domain.FTPConfig
}

// ExecuteWithBytes uploads previously captured PNG bytes and copies the exact
// remote path semantics shown in Settings: FTP paths are rooted at "/", while
// SFTP paths are relative to the authenticated user's home directory.
func (s *CaptureAndFTPService) ExecuteWithBytes(ctx context.Context, pngBytes []byte) error {
	if s.Uploader == nil {
		s.notifyFailure("FTP/SFTP not configured")
		return fmt.Errorf("ftp uploader is nil")
	}
	if len(pngBytes) == 0 {
		s.notifyFailure("empty screenshot")
		return fmt.Errorf("empty screenshot")
	}

	relPath, err := buildFTPRemotePath(s.Cfg.PathPrefix)
	if err != nil {
		s.notifyFailure(err.Error())
		return err
	}

	protocol := normalizedFTPProtocol(s.Cfg.Protocol)
	start := time.Now()
	ftpSvcLog().Info("file-transfer pipeline start",
		"protocol", protocol,
		"host", s.Cfg.Host,
		"user", s.Cfg.User,
		"port", s.Cfg.Port,
		"size", len(pngBytes),
		"remote_path", relPath,
		"strict_host_key", s.Cfg.StrictHostKey)

	if err := s.Uploader.Upload(ctx, relPath, pngBytes); err != nil {
		ftpSvcLog().Error("file-transfer upload failed",
			"protocol", protocol,
			"remote_path", relPath,
			"elapsed", time.Since(start),
			"err", err)
		s.notifyFailure(strings.ToUpper(protocol) + " upload failed: " + err.Error())
		return err
	}

	clipText := ftpShareText(protocol, relPath)
	if s.Clipboard != nil {
		if err := s.Clipboard.WriteText(clipText); err != nil {
			s.notifyFailure("clipboard write failed: " + err.Error())
			return err
		}
	}
	if s.Notifier != nil {
		s.Notifier.NotifySuccess(clipText)
	}
	ftpSvcLog().Info("file-transfer pipeline done",
		"protocol", protocol,
		"remote_path", relPath,
		"total_elapsed", time.Since(start))
	return nil
}

// buildFTPRemotePath validates the user-controlled prefix before reusing the
// existing dated remote-path generator shared with SSH/SCP.
func buildFTPRemotePath(prefix string) (string, error) {
	if err := validateFTPPathPrefix(prefix); err != nil {
		return "", err
	}
	prefix = strings.TrimSpace(prefix)
	prefix = strings.TrimPrefix(prefix, "~")
	prefix = strings.TrimLeft(prefix, "/")
	return buildRemoteRelPath(prefix), nil
}

func validateFTPPathPrefix(prefix string) error {
	if strings.ContainsAny(prefix, "\x00\r\n\\") {
		return fmt.Errorf("FTP/SFTP path contains an invalid character")
	}
	prefix = strings.TrimSpace(prefix)
	prefix = strings.TrimPrefix(prefix, "~")
	prefix = strings.TrimLeft(prefix, "/")
	for _, segment := range strings.Split(prefix, "/") {
		if segment == ".." {
			return fmt.Errorf("FTP/SFTP path must stay inside the login directory")
		}
	}
	return nil
}

func normalizedFTPProtocol(protocol string) string {
	if protocol == domain.FTPProtocolSFTP {
		return domain.FTPProtocolSFTP
	}
	return domain.FTPProtocolFTP
}

func ftpShareText(protocol, relPath string) string {
	if protocol == domain.FTPProtocolSFTP {
		return "~/" + relPath
	}
	return "/" + relPath
}

func (s *CaptureAndFTPService) notifyFailure(reason string) {
	if s.Notifier != nil {
		s.Notifier.NotifyFailure(reason)
	}
}