package build

import (
	"bufio"
	"os"
	"path/filepath"

	"git.akyoto.dev/cli/q/build/elf"
)

// Build describes a compiler build.
type Build struct {
	ExecutableName  string
	ExecutablePath  string
	WriteExecutable bool
}

// New creates a new build.
func New(directory string) (*Build, error) {
	directory, err := filepath.Abs(directory)

	if err != nil {
		return nil, err
	}

	executableName := filepath.Base(directory)

	build := &Build{
		ExecutableName:  executableName,
		ExecutablePath:  filepath.Join(directory, executableName),
		WriteExecutable: true,
	}

	return build, nil
}

// Run parses the input files and generates an executable file.
func (build *Build) Run() error {
	if build.WriteExecutable {
		sampleCode := []byte{
			0xb8, 0x01, 0x00, 0x00, 0x00, // mov eax, 1
			0xbf, 0x01, 0x00, 0x00, 0x00, // mov edi, 1
			0xbe, 0x80 + 0x22, 0x00, 0x40, 0x00, // mov esi, 0x4000A2
			0xba, 0x06, 0x00, 0x00, 0x00, // mov edx, 6
			0x0f, 0x05, // syscall

			0xb8, 0x3c, 0x00, 0x00, 0x00, // mov eax, 60
			0xbf, 0x00, 0x00, 0x00, 0x00, // mov edi, 0
			0x0f, 0x05, // syscall

			'H', 'e', 'l', 'l', 'o', '\n',
		}

		return writeToDisk(build.ExecutablePath, sampleCode, nil)
	}

	return nil
}

// writeToDisk writes the executable file to disk.
func writeToDisk(filePath string, code []byte, data []byte) error {
	file, err := os.Create(filePath)

	if err != nil {
		return err
	}

	buffer := bufio.NewWriter(file)
	executable := elf.New(code)
	executable.Write(buffer)
	buffer.Flush()

	err = file.Close()

	if err != nil {
		return err
	}

	return os.Chmod(filePath, 0755)
}