package srt

import (
	"os"
	"io"
	"strings"
	"stream_server/transcoder"
	"time"
	"path/filepath"
)

// spawn a transcoder instance and return its stdin pipe
func NewWriter(stream_key string) (io.WriteCloser, error) {
	transcoder_in, err := transcoder.NewTranscoder(stream_key)
	if err != nil {
		return nil, err
	}
	return transcoder_in, nil
}

// check if the init.mp4 segment has been modified in between a given sleep time
// if it hasn't (stream disconnected for longer) delete it
// else a new stream has started which shouldn't be deleted
func CleanFiles(stream_key string, delay time.Duration) {
	time.Sleep(delay * time.Second)
	base_dir, _ := os.UserHomeDir()
	stream_dir := base_dir + "/live/" + stream_key
	fileinfo, file_ok := os.Stat(stream_dir + "/init.mp4")
	if file_ok != nil {
		return
	}
	if time.Now().Sub(fileinfo.ModTime()) > delay * time.Second {
		leftover_files, _ := filepath.Glob(stream_dir + "/*")
		for _, file := range leftover_files {
			os.Remove(file)
		}
	}
}

// stream_id is in reverse order, len is multiple of 4 padded with 0
// get the string, check if corresponding folder exists, then attempt
// to spawn a transcoder instance
func CheckStreamID(stream_id []byte) (io.WriteCloser, string, bool) {
	stream_key := make([]byte, 0)
	for i := len(stream_id) - 1; i >= 0; i-- {
		if stream_id[i] == 0 {
			break
		}
		stream_key = append(stream_key, stream_id[i])
	}
	stream_key_string := strings.TrimSpace(string(stream_key))
	if check_stream_key(stream_key_string) {
		writer, err := NewWriter(stream_key_string)
		if err != nil {
			return nil, stream_key_string, false
		}
		return writer, stream_key_string, true
	}
	return nil, stream_key_string, false
}

// checks if folder exists corresponding to the stream_key
func check_stream_key(stream_key string) (bool) {
	base_dir, _ := os.UserHomeDir()
	if fileinfo, err := os.Stat(base_dir + "/live/" + stream_key); err == nil && fileinfo.IsDir() {
		return true
	}
	return false
}