// backend\log.go

package main

import (
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"
)

var (
	appLogMu   sync.Mutex
	appLogFile *os.File
)

func appLogPath() string {
	exePath, _ := os.Executable()
	exeDir := ""

	if exePath != "" {
		exeDir = filepath.Dir(exePath)
	}

	if exeDir == "" {
		exeDir, _ = os.Getwd()
	}

	return filepath.Join(exeDir, "recorder.log")
}

func openAppLogFile() (*os.File, error) {
	path := appLogPath()

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

	return os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
}

func initAppLog() {
	appLogMu.Lock()
	defer appLogMu.Unlock()

	if appLogFile != nil {
		return
	}

	f, err := openAppLogFile()
	if err != nil {
		// Wichtig: hier NICHT appLogln verwenden, weil appLogMu schon gelockt ist.
		fmt.Println("⚠️ recorder log konnte nicht geöffnet werden:", err)
		return
	}

	appLogFile = f

	_, _ = fmt.Fprintf(
		appLogFile,
		"\n\n--- Recorder Start %s ---\nlog=%s\n",
		time.Now().Format(time.RFC3339),
		appLogPath(),
	)
	_ = appLogFile.Sync()
}

func closeAppLog() {
	appLogMu.Lock()
	defer appLogMu.Unlock()

	if appLogFile == nil {
		return
	}

	_, _ = fmt.Fprintf(
		appLogFile,
		"--- Recorder Stop %s ---\n",
		time.Now().Format(time.RFC3339),
	)

	_ = appLogFile.Sync()
	_ = appLogFile.Close()
	appLogFile = nil
}

func appLogWriter() io.Writer {
	initAppLog()

	appLogMu.Lock()
	defer appLogMu.Unlock()

	if appLogFile != nil {
		return appLogFile
	}

	return os.Stderr
}

func appLogWriteLine(line string) {
	line = strings.TrimRight(line, "\r\n")

	ts := time.Now().Format("2006-01-02 15:04:05")
	out := fmt.Sprintf("[%s] %s\n", ts, line)

	appLogMu.Lock()
	defer appLogMu.Unlock()

	fmt.Print(out)

	if appLogFile != nil {
		_, _ = appLogFile.WriteString(out)
		_ = appLogFile.Sync()
	}
}

func appLogln(args ...any) {
	appLogWriteLine(fmt.Sprintln(args...))
}

func appLogf(format string, args ...any) {
	appLogWriteLine(fmt.Sprintf(format, args...))
}

func appErrorf(format string, args ...any) error {
	err := fmt.Errorf(format, args...)
	appLogln("❌", err)
	return err
}

// Nur zentraler Ersatz für fmt.Sprintf.
// Loggt absichtlich NICHT, weil Sprintf oft nur UI-/Command-Strings baut.
func appSprintf(format string, args ...any) string {
	return fmt.Sprintf(format, args...)
}

// Zentraler Ersatz für fmt.Sprint.
func appSprint(args ...any) string {
	return fmt.Sprint(args...)
}

func appLogHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "Nur GET erlaubt", http.StatusMethodNotAllowed)
		return
	}

	path := appLogPath()

	maxBytes := int64(64 * 1024)
	switch strings.TrimSpace(r.URL.Query().Get("maxBytes")) {
	case "16384":
		maxBytes = 16 * 1024
	case "32768":
		maxBytes = 32 * 1024
	case "131072":
		maxBytes = 128 * 1024
	case "262144":
		maxBytes = 256 * 1024
	}

	info, err := os.Stat(path)
	if err != nil {
		if os.IsNotExist(err) {
			writeJSON(w, http.StatusOK, map[string]any{
				"ok":     false,
				"path":   path,
				"exists": false,
				"log":    "",
				"error":  "Logdatei existiert noch nicht.",
			})
			return
		}

		writeJSON(w, http.StatusOK, map[string]any{
			"ok":     false,
			"path":   path,
			"exists": false,
			"log":    "",
			"error":  err.Error(),
		})
		return
	}

	if info.IsDir() {
		writeJSON(w, http.StatusOK, map[string]any{
			"ok":     false,
			"path":   path,
			"exists": true,
			"log":    "",
			"error":  "Logpfad ist ein Ordner.",
		})
		return
	}

	f, err := os.Open(path)
	if err != nil {
		writeJSON(w, http.StatusOK, map[string]any{
			"ok":     false,
			"path":   path,
			"exists": true,
			"log":    "",
			"error":  err.Error(),
		})
		return
	}
	defer f.Close()

	size := info.Size()
	offset := int64(0)
	if size > maxBytes {
		offset = size - maxBytes
	}

	buf := make([]byte, size-offset)
	if len(buf) > 0 {
		if _, err := f.ReadAt(buf, offset); err != nil && err != io.EOF {
			writeJSON(w, http.StatusOK, map[string]any{
				"ok":     false,
				"path":   path,
				"exists": true,
				"log":    "",
				"error":  err.Error(),
			})
			return
		}
	}

	logText := string(buf)
	if offset > 0 {
		logText = "… Log gekürzt, zeige die letzten " + fmt.Sprint(maxBytes/1024) + " KB …\n\n" + logText
	}

	writeJSON(w, http.StatusOK, map[string]any{
		"ok":        true,
		"path":      path,
		"exists":    true,
		"sizeBytes": size,
		"log":       logText,
	})
}

func clearAppLog() {
	appLogMu.Lock()
	defer appLogMu.Unlock()

	if appLogFile != nil {
		_ = appLogFile.Close()
		appLogFile = nil
	}

	path := appLogPath()

	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
		fmt.Println("⚠️ recorder log dir konnte nicht erstellt werden:", err)
		return
	}

	if err := os.WriteFile(path, []byte{}, 0644); err != nil {
		fmt.Println("⚠️ recorder log konnte nicht geleert werden:", err)
	}
}