package web

import (
	"errors"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"runtime"

	"github.com/adrg/xdg"
	"github.com/mholt/archiver/v3"
	"go.jolheiser.com/eget/forge"
)

var (
	amd64Re   = regexp.MustCompile(`amd64|x86_64|64-bit`)
	linuxRe   = regexp.MustCompile(`linux`)
	windowsRe = regexp.MustCompile(`windows`)
)

func Install(f forge.Forger) error {
	var re *regexp.Regexp
	switch runtime.GOOS {
	case "linux":
		re = linuxRe
	case "windows":
		re = windowsRe
	default:
		return fmt.Errorf("%q is not a supported OS", runtime.GOOS)
	}

	latest, err := f.Latest()
	if err != nil {
		return err
	}

	var asset forge.Asset
	for _, a := range latest.Assets {
		if amd64Re.MatchString(a.DownloadURL) && re.MatchString(a.DownloadURL) {
			asset = a
		}
	}

	if asset.Name == "" {
		return errors.New("no release found for this OS")
	}

	tmp, err := os.MkdirTemp(os.TempDir(), "eget-*")
	if err != nil {
		return err
	}
	defer os.RemoveAll(tmp)

	resp, err := http.Get(asset.DownloadURL)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	tmpDest := filepath.Join(tmp, asset.Name)
	fi, err := os.Create(tmpDest)
	if err != nil {
		return err
	}

	if _, err := io.Copy(fi, resp.Body); err != nil {
		return err
	}
	if err := fi.Close(); err != nil {
		return err
	}

	if err := unpack(tmpDest, f.Name()); err != nil {
		return fmt.Errorf("could not unpack download: %w", err)
	}

	return nil
}

func detectRootDir(path string) bool {
	infos, err := os.ReadDir(path)
	if err != nil {
		return false
	}
	return len(infos) != 1
}

func unpack(src, name string) error {
	dest := filepath.Join(xdg.DataHome, name)
	uaIface, err := archiver.ByExtension(src)
	if err != nil {
		return err
	}
	u, ok := uaIface.(archiver.Unarchiver)
	if !ok {
		d, ok := uaIface.(archiver.Decompressor)
		if !ok {
			return fmt.Errorf("format specified by source filename is not an archive or compression format: %s (%T)", src, uaIface)
		}
		var binExt string
		if runtime.GOOS == "windows" {
			binExt = ".exe"
		}
		dest = filepath.Join(dest, name+binExt)
		c := archiver.FileCompressor{Decompressor: d}
		if err := c.DecompressFile(src, dest); err != nil {
			return err
		}
		return os.Chmod(dest, 0o755)
	}
	return u.Unarchive(src, dest)
}