package main

import (
	"bytes"
	"io"
)

func ReadAfterSeq(r io.Reader, size int64, seq byte, callback func([]byte)) {
	var (
		bytes1  []byte
		pointer int64
	)
	for {
		buf := make([]byte, 200)
		n, err := r.Read(buf)
		int64n := int64(n)

		if err == io.EOF {
			break
		}
		var begin int64 = -1
		// 若之前指针就大于设置长度开始指向头
		if pointer >= size {
			begin = 0
		} else if pointer+int64n >= size { // 若尾巴大于
			begin = size - pointer
		}
		pointer += int64n
		if begin == -1 {
			continue
		}

		// 查看当前片段是否存在分隔符
		for _, b := range buf[begin:n] {
			// if b == 13 {
			// 	continue
			// }
			if b == seq {
				bytes2 := bytes.TrimSpace(bytes1)
				if len(bytes2) > 0 {
					callback(bytes2)
					bytes1 = nil
				}
				continue
			}
			bytes1 = append(bytes1, b)
		}

	}
	if len(bytes1) > 0 {
		callback(bytes1)
	}
}