package updater

import (
	"archive/zip"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"daily-timer/internal/version"
)

const (
	GiteaAPIURL    = "https://git.movida.biz/api/v1/repos/bell/daily-timer/releases/latest"
	AppName        = "Daily Timer.app"
	InstallPath    = "/Applications"
	DownloadPrefix = "Daily-Timer-"
)

type Release struct {
	TagName     string  `json:"tag_name"`
	Name        string  `json:"name"`
	Body        string  `json:"body"`
	PublishedAt string  `json:"published_at"`
	Assets      []Asset `json:"assets"`
}

type Asset struct {
	Name               string `json:"name"`
	Size               int64  `json:"size"`
	BrowserDownloadURL string `json:"browser_download_url"`
}

type UpdateInfo struct {
	Available      bool   `json:"available"`
	CurrentVersion string `json:"currentVersion"`
	LatestVersion  string `json:"latestVersion"`
	ReleaseNotes   string `json:"releaseNotes"`
	DownloadURL    string `json:"downloadURL"`
	DownloadSize   int64  `json:"downloadSize"`
}

type Updater struct {
	latestRelease *Release
	downloadURL   string
}

func New() *Updater {
	return &Updater{}
}

func (u *Updater) CheckForUpdates() (*UpdateInfo, error) {
	client := &http.Client{Timeout: 10 * time.Second}

	resp, err := client.Get(GiteaAPIURL)
	if err != nil {
		return nil, fmt.Errorf("failed to check for updates: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("API returned status %d", resp.StatusCode)
	}

	var release Release
	if err := json.NewDecoder(resp.Body).Decode(&release); err != nil {
		return nil, fmt.Errorf("failed to parse release info: %w", err)
	}

	u.latestRelease = &release

	// Find macOS arm64 asset
	var downloadAsset *Asset
	for i := range release.Assets {
		if strings.Contains(release.Assets[i].Name, "macos-arm64") && strings.HasSuffix(release.Assets[i].Name, ".zip") {
			downloadAsset = &release.Assets[i]
			break
		}
	}

	if downloadAsset == nil {
		return nil, fmt.Errorf("no macOS arm64 asset found")
	}

	u.downloadURL = downloadAsset.BrowserDownloadURL

	latestVersion := strings.TrimPrefix(release.TagName, "v")
	currentVersion := strings.TrimPrefix(version.Version, "v")

	info := &UpdateInfo{
		Available:      isNewerVersion(latestVersion, currentVersion),
		CurrentVersion: version.Version,
		LatestVersion:  release.TagName,
		ReleaseNotes:   release.Body,
		DownloadURL:    downloadAsset.BrowserDownloadURL,
		DownloadSize:   downloadAsset.Size,
	}

	return info, nil
}

func (u *Updater) DownloadAndInstall(progressCallback func(float64)) error {
	if u.downloadURL == "" {
		return fmt.Errorf("no download URL available, run CheckForUpdates first")
	}

	// Create temp directory
	tmpDir, err := os.MkdirTemp("", "daily-timer-update-")
	if err != nil {
		return fmt.Errorf("failed to create temp directory: %w", err)
	}
	defer func() { _ = os.RemoveAll(tmpDir) }()

	zipPath := filepath.Join(tmpDir, "update.zip")

	// Download ZIP
	if err := u.downloadFile(zipPath, progressCallback); err != nil {
		return fmt.Errorf("failed to download update: %w", err)
	}

	// Extract ZIP
	extractPath := filepath.Join(tmpDir, "extracted")
	if err := u.extractZip(zipPath, extractPath); err != nil {
		return fmt.Errorf("failed to extract update: %w", err)
	}

	// Find .app in extracted folder
	appPath := filepath.Join(extractPath, AppName)
	if _, err := os.Stat(appPath); os.IsNotExist(err) {
		return fmt.Errorf("app not found in update package")
	}

	// Remove old app from /Applications
	destPath := filepath.Join(InstallPath, AppName)
	if _, err := os.Stat(destPath); err == nil {
		if err := os.RemoveAll(destPath); err != nil {
			return fmt.Errorf("failed to remove old app: %w", err)
		}
	}

	// Copy new app to /Applications
	if err := u.copyDir(appPath, destPath); err != nil {
		return fmt.Errorf("failed to install update: %w", err)
	}

	// Remove quarantine attribute
	cmd := exec.Command("xattr", "-cr", destPath)
	if err := cmd.Run(); err != nil {
		fmt.Printf("Warning: failed to remove quarantine: %v\n", err)
	}

	return nil
}

func (u *Updater) RestartApp() error {
	destPath := filepath.Join(InstallPath, AppName)

	// Launch new app
	cmd := exec.Command("open", destPath)
	if err := cmd.Start(); err != nil {
		return fmt.Errorf("failed to launch updated app: %w", err)
	}

	// Exit current app
	os.Exit(0)
	return nil
}

func (u *Updater) downloadFile(destPath string, progressCallback func(float64)) error {
	resp, err := http.Get(u.downloadURL)
	if err != nil {
		return err
	}
	defer func() { _ = resp.Body.Close() }()

	out, err := os.Create(destPath)
	if err != nil {
		return err
	}
	defer func() { _ = out.Close() }()

	totalSize := resp.ContentLength
	var downloaded int64 = 0

	buf := make([]byte, 32*1024)
	for {
		n, err := resp.Body.Read(buf)
		if n > 0 {
			if _, writeErr := out.Write(buf[:n]); writeErr != nil {
				return writeErr
			}
			downloaded += int64(n)
			if progressCallback != nil && totalSize > 0 {
				progressCallback(float64(downloaded) / float64(totalSize))
			}
		}
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}
	}

	return nil
}

func (u *Updater) extractZip(zipPath, destPath string) error {
	r, err := zip.OpenReader(zipPath)
	if err != nil {
		return err
	}
	defer func() { _ = r.Close() }()

	if err := os.MkdirAll(destPath, 0755); err != nil {
		return err
	}

	for _, f := range r.File {
		fpath := filepath.Join(destPath, f.Name)

		// Prevent ZipSlip vulnerability
		if !strings.HasPrefix(fpath, filepath.Clean(destPath)+string(os.PathSeparator)) {
			return fmt.Errorf("illegal file path: %s", fpath)
		}

		if f.FileInfo().IsDir() {
			_ = os.MkdirAll(fpath, f.Mode())
			continue
		}

		if err := os.MkdirAll(filepath.Dir(fpath), 0755); err != nil {
			return err
		}

		outFile, err := os.OpenFile(fpath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, f.Mode())
		if err != nil {
			return err
		}

		rc, err := f.Open()
		if err != nil {
			_ = outFile.Close()
			return err
		}

		_, err = io.Copy(outFile, rc)
		_ = outFile.Close()
		_ = rc.Close()

		if err != nil {
			return err
		}
	}

	return nil
}

func (u *Updater) copyDir(src, dst string) error {
	return filepath.Walk(src, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		relPath, err := filepath.Rel(src, path)
		if err != nil {
			return err
		}

		dstPath := filepath.Join(dst, relPath)

		if info.IsDir() {
			return os.MkdirAll(dstPath, info.Mode())
		}

		// Handle symlinks
		if info.Mode()&os.ModeSymlink != 0 {
			link, err := os.Readlink(path)
			if err != nil {
				return err
			}
			return os.Symlink(link, dstPath)
		}

		srcFile, err := os.Open(path)
		if err != nil {
			return err
		}
		defer func() { _ = srcFile.Close() }()

		dstFile, err := os.OpenFile(dstPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, info.Mode())
		if err != nil {
			return err
		}
		defer func() { _ = dstFile.Close() }()

		_, err = io.Copy(dstFile, srcFile)
		return err
	})
}

// isNewerVersion compares semver-like versions (e.g., "0.1.0" vs "0.2.0")
func isNewerVersion(latest, current string) bool {
	if current == "dev" || current == "unknown" {
		return true
	}

	latest = strings.TrimPrefix(latest, "v")
	current = strings.TrimPrefix(current, "v")

	// Handle dirty versions (e.g., "0.1.0-dirty" or "0.1.0-3-g1234567")
	if strings.Contains(current, "-") {
		parts := strings.Split(current, "-")
		current = parts[0]
	}

	latestParts := strings.Split(latest, ".")
	currentParts := strings.Split(current, ".")

	for i := 0; i < len(latestParts) && i < len(currentParts); i++ {
		var l, c int
		_, _ = fmt.Sscanf(latestParts[i], "%d", &l)
		_, _ = fmt.Sscanf(currentParts[i], "%d", &c)

		if l > c {
			return true
		} else if l < c {
			return false
		}
	}

	return len(latestParts) > len(currentParts)
}