package fat

import (
	"fmt"
	"io"
	"os"
	"strings"
)

// Split a Fat binary into multiple Mach-O binaries
// @ifile: path to Fat binary
// returns a list of file path of splited Mach-O binaries
func CreateMachosFromFat(ifile string) ([]string, error) {
	f, err := os.OpenFile(ifile, os.O_RDONLY, 0644)
	if err != nil {
		fmt.Println("Cannot open file")
		return []string{}, err
	}

	var fc FatContext
	fc.ParseFile(f)

	var r []string
	for _, arch := range fc.Machos() {
		offset := arch.Offset
		size := arch.Size
		buf := make([]byte, size)
		filename := fmt.Sprintf(
			"%s_%x",
			strings.ReplaceAll(ifile, " ", "_"),
			offset,
		)

		var err error
		_, err = f.Seek(int64(offset), io.SeekStart)
		if err != nil {
			return r, err
		}

		_, err = f.Read(buf)
		if err != nil {
			return r, err
		}

		outfile, err := os.OpenFile(
			filename,
			os.O_CREATE|os.O_WRONLY,
			0777,
		)
		if err != nil {
			return r, err
		}

		_, err = outfile.Write(buf)
		if err != nil {
			return r, err
		}

		r = append(r, filename) // everything is find, append new file path
	}
	return r, nil
}