jldb/fstore/command.go

package fstore

import (
	"bytes"
	"encoding/binary"
	"io"

	"git.crumpington.com/public/jldb/lib/errs"
)

type command struct {
	Path     string
	Store    bool
	TempID   uint64
	FileSize int64 // In bytes.
	File     io.Reader
}

func (c command) Reader(buf *bytes.Buffer) (int64, io.Reader) {
	buf.Reset()
	vars := []any{
		uint32(len(c.Path)),
		c.Store,
		c.TempID,
		c.FileSize,
	}

	for _, v := range vars {
		binary.Write(buf, binary.LittleEndian, v)
	}
	buf.Write([]byte(c.Path))

	if c.Store {
		return int64(buf.Len()) + c.FileSize, io.MultiReader(buf, c.File)
	} else {
		return int64(buf.Len()), buf
	}
}

func (c *command) ReadFrom(r io.Reader) error {
	pathLen := uint32(0)

	ptrs := []any{
		&pathLen,
		&c.Store,
		&c.TempID,
		&c.FileSize,
	}

	for _, ptr := range ptrs {
		if err := binary.Read(r, binary.LittleEndian, ptr); err != nil {
			return errs.IO.WithErr(err)
		}
	}

	pathBuf := make([]byte, pathLen)
	if _, err := r.Read(pathBuf); err != nil {
		return errs.IO.WithErr(err)
	}

	c.Path = string(pathBuf)
	c.File = r

	return nil
}