package drive

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
)

const binaryName = "proton-drive"

// Lookup returns the full path to the proton-drive binary in PATH.
func Lookup() (string, error) {
	return exec.LookPath(binaryName)
}

// CheckAuth verifies that the user is authenticated by listing /my-files.
func CheckAuth() error {
	binary, err := Lookup()
	if err != nil {
		return fmt.Errorf("proton-drive not found in PATH: %w", err)
	}

	cmd := exec.Command(binary, "filesystem", "list", "/my-files")
	cmd.Stdout = nil
	cmd.Stderr = nil

	if err := cmd.Run(); err != nil {
		return fmt.Errorf("not authenticated with proton-drive (run 'proton-drive auth login'): %w", err)
	}
	return nil
}

// Upload uploads localPath to remotePath on Proton Drive.
// remotePath is a full path including filename (e.g. /my-files/md/report.md).
// The CLI uploads to a parent directory and preserves the local filename,
// so if the remote filename differs from the local one, a temp copy is staged.
// Existing remote files are overwritten (--conflict-strategy replace).
func Upload(localPath, remotePath string) error {
	binary, err := Lookup()
	if err != nil {
		return fmt.Errorf("proton-drive not found in PATH: %w", err)
	}

	remoteDir := filepath.Dir(remotePath)
	remoteName := filepath.Base(remotePath)
	localName := filepath.Base(localPath)

	if remoteName == localName {
		return runUpload(binary, localPath, remoteDir)
	}

	tmpDir, err := os.MkdirTemp("", "dirmd-upload-*")
	if err != nil {
		return fmt.Errorf("cannot create temp dir: %w", err)
	}
	defer os.RemoveAll(tmpDir)

	tmpFile := filepath.Join(tmpDir, remoteName)
	if err := copyFile(localPath, tmpFile); err != nil {
		return fmt.Errorf("cannot stage temp file: %w", err)
	}

	return runUpload(binary, tmpFile, remoteDir)
}

func runUpload(binary, localPath, remoteDir string) error {
	cmd := exec.Command(binary, "filesystem", "upload", localPath, remoteDir,
		"--conflict-strategy", "replace")

	var stderr strings.Builder
	cmd.Stderr = &stderr

	if err := cmd.Run(); err != nil {
		return fmt.Errorf("upload to proton-drive failed: %w: %s",
			err, strings.TrimSpace(stderr.String()))
	}
	return nil
}

func copyFile(src, dst string) error {
	data, err := os.ReadFile(src)
	if err != nil {
		return err
	}
	return os.WriteFile(dst, data, 0644)
}