using System.IO;
using UnityEngine;

namespace Net.BITKit
{
    public static class AudioClipUtils
    {
        public static byte[] AudioClipToWavBytes(AudioClip clip)
        {
            var samples = new float[clip.samples * clip.channels];
            clip.GetData(samples, 0);

            var wavData = ConvertToWav(samples, clip.channels, clip.frequency);
            return wavData;
        }

        private static byte[] ConvertToWav(float[] samples, int channels, int sampleRate)
        {
            var stream = new MemoryStream();
            var writer = new BinaryWriter(stream);

            var byteRate = sampleRate * channels * 2;

            // 写入 WAV 文件头
            writer.Write(System.Text.Encoding.ASCII.GetBytes("RIFF"));
            writer.Write(0); // placeholder for total file size
            writer.Write(System.Text.Encoding.ASCII.GetBytes("WAVE"));

            // fmt 块
            writer.Write(System.Text.Encoding.ASCII.GetBytes("fmt "));
            writer.Write(16); // PCM
            writer.Write((short)1); // AudioFormat = PCM
            writer.Write((short)channels);
            writer.Write(sampleRate);
            writer.Write(byteRate);
            writer.Write((short)(channels * 2)); // Block align
            writer.Write((short)16); // Bits per sample

            // data 块
            writer.Write(System.Text.Encoding.ASCII.GetBytes("data"));
            writer.Write(0); // placeholder for data chunk size

            // 写入样本
            var sampleCount = samples.Length;
            for (var i = 0; i < sampleCount; i++)
            {
                var intData = (short)(samples[i] * short.MaxValue);
                writer.Write(intData);
            }

            // 回写文件长度
            writer.Seek(4, SeekOrigin.Begin);
            writer.Write((int)(stream.Length - 8)); // RIFF size

            writer.Seek(40, SeekOrigin.Begin);
            writer.Write((int)(stream.Length - 44)); // data chunk size

            writer.Flush();
            return stream.ToArray();
        }
    }


}