package icsutil

import (
	"batchmodule/icsconf"
	"batchmodule/icserror"
	"batchmodule/icslog"
	"encoding/binary"
	"fmt"
	"io"
	"log"
	"os"
)

var (
	conf icsconf.AppInfo
	l    *log.Logger
)

func init() {
	conf = icsconf.Getconfig()
	l = icslog.InitializeLogger()
}

func DeletePcmFolder(dir string) (bool, *icserror.IcsError) {
	l.Println("util.go>deletePcmFolder> dir: ", dir)
	if _, err := os.Stat(dir); os.IsNotExist(err) {
		l.Println("Error at util.go>deletePcmFolder> pcm folder does not exist with the dir: ", dir)
		return false, icserror.ICSERRFileOpen
	}
	err := os.RemoveAll(dir)
	if err != nil {
		l.Panicln("Error at util.go>deletePcmFolder> os.RemoveAll() dir: ", dir)
		return false, icserror.ICSERRWriteFile
	}
	l.Printf(`util.go>deletePcmFolder> %s has been successfully deleted`, dir)
	return true, nil
}

func DevideWavTo2Pcm(fileName string, starttime string) (result bool, folderName string) {
	pcmDir := conf.Directories.PCMDirectory

	starttimeDir := fmt.Sprintf("%s/%s", pcmDir, starttime)
	os.MkdirAll(starttimeDir, os.ModePerm)

	leftOutputFile := fmt.Sprintf(`%s/%s-left.pcm`, starttimeDir, starttime)
	rightOutputFile := fmt.Sprintf(`%s/%s-right.pcm`, starttimeDir, starttime)

	inFile, err := os.Open(fileName)
	if err != nil {
		l.Printf("Error at util.go>devideWavTo2Pcm()> os.Open failed. dir: %s", fileName)
		return false, ""
	}
	defer inFile.Close()

	leftFile, err := os.Create(leftOutputFile)
	if err != nil {
		l.Printf("Error at util.go>devideWavTo2Pcm()> os.Create failed. dir: %s", leftOutputFile)
		return false, ""
	}
	defer leftFile.Close()

	rightFile, err := os.Create(rightOutputFile)
	if err != nil {
		l.Printf("Error at util.go>devideWavTo2Pcm()> os.Create failed. dir: %s", leftOutputFile)
		return false, ""
	}
	defer rightFile.Close()

	// Skip WAV header (44 bytes)
	wavHeader := make([]byte, 44)
	if _, err := inFile.Read(wavHeader); err != nil {
		l.Printf("Error at util.go>devideWavTo2Pcm()> inFile.Read(wavHeader) failed. err: %+v", err)
		return false, ""
	}

	// Check if it's a valid WAV file
	if string(wavHeader[:4]) != "RIFF" || string(wavHeader[8:12]) != "WAVE" {
		l.Printf("Error at util.go>devideWavTo2Pcm()> invalid WAV file format. Header content: %s", string(wavHeader[:4]))
		return false, ""
	}

	// Check if WAV file is stereo
	numChannels := binary.LittleEndian.Uint16(wavHeader[22:24])
	if numChannels != 2 {
		l.Printf("Error at util.go>devideWavTo2Pcm()> unsupported channel count: %d. This function only supports stereo (2 channels)", numChannels)
		return false, ""
	}

	buf := make([]byte, 4) // 2 bytes per sample * 2 channels

	for {
		n, err := inFile.Read(buf)
		if err == io.EOF {
			break
		}
		if err != nil {
			l.Printf("Error at util.go>devideWavTo2Pcm()> inFile.Read(buf) failed. failed to read from input file: %v", err)
			return false, ""
		}

		if n < 4 {
			for i := n; i < 4; i++ {
				buf[i] = 0
			}
			break
		}

		leftSample := buf[:2]
		rightSample := buf[2:]

		if err := binary.Write(leftFile, binary.LittleEndian, leftSample); err != nil {
			l.Printf("Error at util.go>devideWavTo2Pcm()> binary.Write(leftFile, binary.LittleEndian, leftSample) failed. err: %v", err)
			return false, ""
		}

		if err := binary.Write(rightFile, binary.LittleEndian, rightSample); err != nil {
			l.Printf("Error at util.go>devideWavTo2Pcm()> binary.Write(rightFile, binary.LittleEndian, rightSample) failed. err: %v", err)
			return false, ""
		}

	}

	l.Printf("util.go>devideWavTo2Pcm()> WAV file split successfully to dir: %s, %s", leftOutputFile, rightOutputFile)
	return true, starttime
}