package build

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

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

// 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
	}

	file, err := os.Open(directory)

	if err != nil {
		return nil, err
	}

	defer file.Close()
	files, err := file.Readdirnames(0)

	if err != nil {
		return nil, err
	}

	for _, name := range files {
		log.Info.Println(name)
	}

	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 {
	code := build.Compile()

	if build.WriteExecutable {
		return writeToDisk(build.ExecutablePath, code)
	}

	return nil
}

// Compile compiles all the functions.
func (build *Build) Compile() []byte {
	return []byte{
		0xb8, 0x01, 0x00, 0x00, 0x00, // mov eax, 1
		0xbf, 0x01, 0x00, 0x00, 0x00, // mov edi, 1
		0xbe, 0xa2, 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',
	}
}

// writeToDisk writes the executable file to disk.
func writeToDisk(filePath string, code []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)
}