package app

import (
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"
	"sync"
	"time"

	"vrc_osc_go/internal/common"
)

type runtimeLogWriter struct {
	mu   sync.Mutex
	file *os.File
}

func (w *runtimeLogWriter) Write(p []byte) (int, error) {
	w.mu.Lock()
	defer w.mu.Unlock()
	if w.file == nil {
		return len(p), nil
	}
	return w.file.Write(p)
}

func setupRuntimeLogger() error {
	dir := filepath.Join(common.RootDir(), "runtime")
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return err
	}
	path := filepath.Join(dir, "runtime.log")
	f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
	if err != nil {
		return err
	}
	logWriter := &runtimeLogWriter{file: f}
	log.SetOutput(io.MultiWriter(os.Stderr, logWriter))
	return nil
}

func appendRuntimeLog(title, text string) error {
	dir := filepath.Join(common.RootDir(), "runtime")
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return err
	}
	path := filepath.Join(dir, "runtime.log")
	body := text
	if body == "" {
		body = "(empty)"
	}
	f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
	if err != nil {
		return err
	}
	defer f.Close()
	_, err = fmt.Fprintf(f, "\n[%s] %s\n%s\n", time.Now().Format("2006-01-02 15:04:05"), title, body)
	return err
}

func AppendRuntimeLog(title, text string) error {
	return appendRuntimeLog(title, text)
}

func appendJoinLeaveLog(text string) error {
	dir := filepath.Join(common.RootDir(), "runtime")
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return err
	}
	path := filepath.Join(dir, "join_leave.log")
	body := text
	if body == "" {
		body = "(empty)"
	}
	f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
	if err != nil {
		return err
	}
	defer f.Close()
	_, err = fmt.Fprintf(f, "\n[%s] VRC JOIN/LEAVE\n%s\n", time.Now().Format("2006-01-02 15:04:05"), body)
	return err
}

func appendDesktopJoinLog(title, worldLabel, text string) error {
	dir := filepath.Join(os.Getenv("USERPROFILE"), "Desktop")
	if _, err := os.Stat(dir); err != nil {
		if home, herr := os.UserHomeDir(); herr == nil {
			dir = filepath.Join(home, "Desktop")
		}
	}
	if err := os.MkdirAll(dir, 0o755); err != nil {
		dir = filepath.Join(common.RootDir(), "runtime")
		if mkErr := os.MkdirAll(dir, 0o755); mkErr != nil {
			return err
		}
	}
	path := filepath.Join(dir, "join.txt")
	body := text
	if body == "" {
		body = "(empty)"
	}
	f, err := os.OpenFile(path, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o644)
	if err != nil {
		fallbackDir := filepath.Join(common.RootDir(), "runtime")
		if mkErr := os.MkdirAll(fallbackDir, 0o755); mkErr != nil {
			return err
		}
		fallbackPath := filepath.Join(fallbackDir, "join.txt")
		f, err = os.OpenFile(fallbackPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o644)
		if err != nil {
			return err
		}
		path = fallbackPath
	}
	defer f.Close()
	_, err = fmt.Fprintf(f, "%s\nWorld: %s\n\n%s\n", title, worldLabel, body)
	return err
}

func AppendDesktopJoinLog(title, worldLabel, text string) error {
	return appendDesktopJoinLog(title, worldLabel, text)
}