package main

import (
	"bufio"
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"os/signal"
	"path/filepath"
	"runtime"
	"strings"

	"github.com/fatih/color"
	"github.com/mattn/go-mastodon"
	"github.com/mattn/go-tty"
	"github.com/urfave/cli"
	"golang.org/x/net/html"
)

var ()

func readFile(filename string) ([]byte, error) {
	if filename == "-" {
		return ioutil.ReadAll(os.Stdin)
	}
	return ioutil.ReadFile(filename)
}

func textContent(s string) string {
	doc, err := html.Parse(strings.NewReader(s))
	if err != nil {
		return s
	}
	var buf bytes.Buffer

	var extractText func(node *html.Node, w *bytes.Buffer)
	extractText = func(node *html.Node, w *bytes.Buffer) {
		if node.Type == html.TextNode {
			data := strings.Trim(node.Data, "\r\n")
			if data != "" {
				w.WriteString(data)
			}
		}
		for c := node.FirstChild; c != nil; c = c.NextSibling {
			extractText(c, w)
		}
		if node.Type == html.ElementNode {
			name := strings.ToLower(node.Data)
			if name == "br" {
				w.WriteString("\n")
			}
		}
	}
	extractText(doc, &buf)
	return buf.String()
}

var (
	readUsername func() (string, error) = func() (string, error) {
		b, _, err := bufio.NewReader(os.Stdin).ReadLine()
		if err != nil {
			return "", err
		}
		return string(b), nil
	}
	readPassword func() (string, error)
)

func prompt() (string, string, error) {
	t, err := tty.Open()
	if err != nil {
		return "", "", err
	}
	defer t.Close()

	fmt.Print("E-Mail: ")
	email, err := readUsername()
	if err != nil {
		return "", "", err
	}

	fmt.Print("Password: ")
	var password string
	if readPassword == nil {
		password, err = t.ReadPassword()
	} else {
		password, err = readPassword()
	}
	if err != nil {
		return "", "", err
	}
	return email, password, nil
}

func getConfig() (string, *mastodon.Config, error) {
	dir := os.Getenv("HOME")
	if runtime.GOOS == "windows" {
		dir = os.Getenv("APPDATA")
		if dir == "" {
			dir = filepath.Join(os.Getenv("USERPROFILE"), "Application Data", "mstdn")
		}
		dir = filepath.Join(dir, "mstdn")
	} else {
		dir = filepath.Join(dir, ".config", "mstdn")
	}
	if err := os.MkdirAll(dir, 0700); err != nil {
		return "", nil, err
	}
	file := filepath.Join(dir, "settings.json")
	b, err := ioutil.ReadFile(file)
	if err != nil && !os.IsNotExist(err) {
		return "", nil, err
	}
	config := &mastodon.Config{
		Server:       "https://mstdn.jp",
		ClientID:     "171d45f22068a5dddbd927b9d966f5b97971ed1d3256b03d489f5b3a83cdba59",
		ClientSecret: "574a2cf4b3f28a5fa0cfd285fc80cfe9daa419945163ef18f5f3d0022f4add28",
	}
	if err == nil {
		err = json.Unmarshal(b, &config)
		if err != nil {
			return "", nil, fmt.Errorf("could not unmarshal %v: %v", file, err)
		}
	}
	return file, config, nil
}

func authenticate(client *mastodon.Client, config *mastodon.Config, file string) error {
	email, password, err := prompt()
	if err != nil {
		return err
	}
	err = client.Authenticate(email, password)
	if err != nil {
		return err
	}
	b, err := json.MarshalIndent(config, "", "  ")
	if err != nil {
		return fmt.Errorf("failed to store file:", err)
	}
	err = ioutil.WriteFile(file, b, 0700)
	if err != nil {
		return fmt.Errorf("failed to store file:", err)
	}
	return nil
}

func fatalIf(err error) {
	if err == nil {
		return
	}
	fmt.Fprintf(os.Stderr, "%s: %v\n", os.Args[0], err)
	os.Exit(1)
}

func run() int {
	file, config, err := getConfig()
	fatalIf(err)

	client := mastodon.NewClient(config)
	if config.AccessToken == "" {
		err = authenticate(client, config, file)
		fatalIf(err)
	}

	app := cli.NewApp()
	app.Metadata = map[string]interface{}{
		"client": client,
		"config": config,
	}
	app.Name = "mstdn"
	app.Usage = "mastodon client"
	app.Version = "0.0.1"
	app.Commands = []cli.Command{
		{
			Name:  "toot",
			Usage: "post toot",
			Flags: []cli.Flag{
				cli.StringFlag{
					Name:  "ff",
					Usage: "post utf-8 string from a file(\"-\" means STDIN)",
					Value: "",
				},
			},
			Action: cmdToot,
		},
		{
			Name:   "stream",
			Usage:  "stream statuses",
			Action: cmdStream,
		},
		{
			Name:   "timeline",
			Usage:  "show timeline",
			Action: cmdTimeline,
		},
	}
	app.Run(os.Args)
	return 0
}

func cmdToot(c *cli.Context) error {
	if !c.Args().Present() {
		return errors.New("arguments required")
	}

	var toot string
	ff := c.String("ff")
	if ff != "" {
		text, err := readFile(ff)
		if err != nil {
			log.Fatal(err)
		}
		toot = string(text)
	} else {
		toot = strings.Join(c.Args().Tail(), " ")
	}
	client := c.App.Metadata["client"].(*mastodon.Client)
	_, err := client.PostStatus(&mastodon.Toot{
		Status: toot,
	})
	return err
}

func cmdStream(c *cli.Context) error {
	client := c.App.Metadata["client"].(*mastodon.Client)
	ctx, cancel := context.WithCancel(context.Background())
	sc := make(chan os.Signal, 1)
	signal.Notify(sc, os.Interrupt)
	q, err := client.StreamingPublic(ctx)
	if err != nil {
		return err
	}
	go func() {
		<-sc
		cancel()
		close(q)
	}()
	for e := range q {
		switch t := e.(type) {
		case *mastodon.UpdateEvent:
			color.Set(color.FgHiRed)
			fmt.Println(t.Status.Account.Username)
			color.Set(color.Reset)
			fmt.Println(textContent(t.Status.Content))
		case *mastodon.ErrorEvent:
			color.Set(color.FgYellow)
			fmt.Println(t.Error())
			color.Set(color.Reset)
		}
	}
	return nil
}

func cmdTimeline(c *cli.Context) error {
	client := c.App.Metadata["client"].(*mastodon.Client)
	timeline, err := client.GetTimelineHome()
	if err != nil {
		return err
	}
	for i := len(timeline) - 1; i >= 0; i-- {
		t := timeline[i]
		color.Set(color.FgHiRed)
		fmt.Println(t.Account.Username)
		color.Set(color.Reset)
		fmt.Println(textContent(t.Content))
	}
	return nil
}

func main() {
	os.Exit(run())
}