package deps

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

// Dependency describes an external CLI tool the platform may use.
type Dependency struct {
	Name        string `json:"name"`
	Available   bool   `json:"available"`
	Version     string `json:"version,omitempty"`
	Path        string `json:"path,omitempty"`
	Required    bool   `json:"required"`
	InstallHint string `json:"installHint,omitempty"`
}

// CheckAll probes all known external dependencies.
//
// 偵測順序（由 lookupBin 實作）：
//  1. $VISIONA_BUNDLE_BIN_DIR/<name>（Wails shell 啟動 server 時設定）
//  2. exec.LookPath(<name>)（系統 PATH）
func CheckAll() []Dependency {
	return []Dependency{
		check("ffmpeg", false,
			"macOS: brew install ffmpeg | Windows: winget install Gyan.FFmpeg",
			"-version"),
		check("yt-dlp", false,
			"macOS: brew install yt-dlp | Windows: winget install yt-dlp",
			"--version"),
		check("python3", false,
			"Required only for Kneron KL720 hardware. macOS: brew install python3",
			"--version"),
	}
}

// lookupBin 依序在 bundle bin dir 與 PATH 中找 binary。
//
// bundle bin dir 來自 env var VISIONA_BUNDLE_BIN_DIR（由 Wails shell 於啟動
// server 時注入，指向 .app/Contents/Resources/bin/ 或開發模式 payload/darwin/bin/）。
func lookupBin(name string) (string, bool) {
	if dir := strings.TrimSpace(os.Getenv("VISIONA_BUNDLE_BIN_DIR")); dir != "" {
		candidate := filepath.Join(dir, name)
		if info, err := os.Stat(candidate); err == nil && !info.IsDir() {
			return candidate, true
		}
	}
	if p, err := exec.LookPath(name); err == nil {
		return p, true
	}
	return "", false
}

func check(name string, required bool, hint string, args ...string) Dependency {
	d := Dependency{
		Name:        name,
		Required:    required,
		InstallHint: hint,
	}
	path, ok := lookupBin(name)
	if !ok {
		return d
	}
	d.Available = true
	d.Path = path

	// 效能：bundle 內的 binary（尤其是 yt-dlp PyInstaller 單檔）冷啟動可能需 20 秒，
	// 會阻塞 server startup。bundle binary 已知良好，跳過 version 查詢以加速啟動。
	// 若之後需要版本字串，handler 可 lazy 再打一次。
	if strings.HasPrefix(path, strings.TrimSpace(os.Getenv("VISIONA_BUNDLE_BIN_DIR"))) &&
		os.Getenv("VISIONA_BUNDLE_BIN_DIR") != "" {
		d.Version = "(bundled)"
		return d
	}

	out, err := exec.Command(path, args...).Output()
	if err == nil {
		lines := strings.SplitN(string(out), "\n", 2)
		if len(lines) > 0 {
			d.Version = strings.TrimSpace(lines[0])
		}
	}
	return d
}

// Logger is the minimal interface used for startup reporting.
type Logger interface {
	Info(msg string, args ...interface{})
}

// PrintStartupReport logs the status of every external dependency.
func PrintStartupReport(logger Logger) {
	deps := CheckAll()
	logger.Info("External dependency check:")
	if dir := os.Getenv("VISIONA_BUNDLE_BIN_DIR"); dir != "" {
		logger.Info("  (bundle bin dir: %s)", dir)
	}
	for _, d := range deps {
		if d.Available {
			logger.Info("  [OK] %s: %s (%s)", d.Name, d.Version, d.Path)
		} else {
			tag := "OPTIONAL"
			if d.Required {
				tag = "MISSING"
			}
			logger.Info("  [%s] %s: not found — %s", tag, d.Name, d.InstallHint)
		}
	}
}