package ui

import (
	"log"
	"os"
	"time"

	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"path/filepath"

	"github.com/codeclysm/extract"
	"github.com/gotk3/gotk3/glib"
	"varia.zone/hui/internal/conf"
	"varia.zone/hui/internal/model"
)

// PostInitSpinner handles UI tasks after Hugo is downloaded.
func PostInitSpinner(m *model.Model) error {
	if err := SwitchStackPage(m, conf.EmptyStackPage); err != nil {
		return err
	}

	if err := ShowSiteButtons(m); err != nil {
		return err
	}

	return nil
}

// Initialise initialises the program.
func Initialise(m *model.Model) error {
	msg := "Downloading Hugo... this could take a minute..."
	if err := SwitchStackPage(m, conf.BusyStackPage, msg); err != nil {
		return err
	}

	go func() {
		if err := initialise(m.User.HomeDir); err != nil {
			glib.IdleAdd(func() bool {
				if err := ShowErrDialog(m, err); err != nil {
					log.Fatal(fmt.Errorf("main: unable to show error dialog: %s", err))
				}
				return false
			})
		}
	}()

	go func() {
		for {
			if _, err := os.Stat(conf.HugoBinPath(m.User.HomeDir)); err == nil {
				break
			}
			time.Sleep(1)
		}

		glib.IdleAdd(func() bool {
			if err := PostInitSpinner(m); err != nil {
				if err := ShowErrDialog(m, err); err != nil {
					log.Fatal(fmt.Errorf("main: unable to show error dialog: %s", err))
				}
			}
			return false
		})
	}()

	return nil
}

// initialise deals with initial setup functionality.
func initialise(homeDir string) error {
	if err := createDirectories(homeDir); err != nil {
		return err
	}

	if err := downloadHugo(homeDir); err != nil {
		return err
	}

	return nil
}

// httpGetFile downloads a file from the internet.
func httpGetFile(filepath, url string) error {
	out, err := os.Create(filepath)
	if err != nil {
		return fmt.Errorf("httpGetFile: unable to create '%s': %s", filepath, err)
	}
	defer out.Close()

	resp, err := http.Get(url)
	if err != nil {
		return fmt.Errorf("httpGetFile: unable to HTTP GET '%s'", url)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("httpGetFile: HTTP GET response code %v for '%s'", resp.StatusCode, url)
	}

	_, err = io.Copy(out, resp.Body)
	if err != nil {
		return fmt.Errorf("httpGetFile: unable to copy HTTP GET response to disk: %s", err)
	}

	return nil
}

// downloadHugo downloads Hugo.
func downloadHugo(homeDir string) error {
	hugoTarPath := filepath.Join(conf.HugoDir(homeDir), fmt.Sprintf("hugo-%s.tar.gz", conf.HugoVersion))

	if _, err := os.Stat(conf.HugoBinPath(homeDir)); err == nil {
		return nil
	} else if errors.Is(err, os.ErrNotExist) {
		if err := httpGetFile(hugoTarPath, conf.HugoReleaseURL); err != nil {
			return err
		}
	}

	fpath, err := ioutil.ReadFile(hugoTarPath)
	if err != nil {
		return fmt.Errorf("downloadHugo: unable to read file '%s': %s", hugoTarPath, err)
	}

	if err := extract.Gz(context.TODO(), bytes.NewBuffer(fpath), conf.HugoDir(homeDir), nil); err != nil {
		return fmt.Errorf("downloadHugo: unable to extract file '%s': %s", hugoTarPath, err)
	}

	return nil
}

// createDirectories creates all necessary application directories.
func createDirectories(homeDir string) error {
	paths := []string{
		conf.DataDir(homeDir),
		conf.HugoDir(homeDir),
		conf.SitesDir(homeDir),
	}

	for _, fpath := range paths {
		if _, err := os.Stat(fpath); err != nil && os.IsNotExist(err) {
			if err := os.Mkdir(fpath, 0764); err != nil {
				return fmt.Errorf("createDirectories: unable to create '%s': %s", fpath, err)
			}
		}
	}

	return nil
}