package saltyim

import (
	"bytes"
	"context"
	"fmt"
	"strings"
	"sync"

	"github.com/dim13/crc24"
	"github.com/gdamore/tcell/v2"
	"github.com/keys-pub/keys"
	"github.com/posener/formatter"
	"github.com/rivo/tview"
	log "github.com/sirupsen/logrus"
	"go.mills.io/salty"
	"go.yarn.social/lextwt"
)

const (
	dateTimeFormat = "2006-01-02 15:04:05"
)

func getUserColor(s string) tcell.Color {
	c := crc24.Sum([]byte(s))
	return tcell.NewRGBColor(
		int32(c>>0x10),
		int32(c>>0x08),
		int32(c),
	)
}

type chatClient struct {
	mu sync.RWMutex

	key    *keys.EdX25519Key
	uri    string
	me     Addr
	inbox  string
	user   string
	config Config

	// Configurations.
	palette map[string]string
}

// NewChatClient initializes a new chatClient.
// Sets up connection with broker, and initializes UI.
func NewChatClient(key *keys.EdX25519Key, uri string, me Addr, inbox, user string) (*chatClient, error) {
	config, err := Lookup(user)
	if err != nil {
		return nil, fmt.Errorf("error: failed to lookup user %q: %w", user, err)
	}

	return &chatClient{
		key:    key,
		uri:    uri,
		me:     me,
		inbox:  inbox,
		user:   user,
		config: config,

		palette: map[string]string{
			"background": "000000",
			"border":     "4C5C68",
			"title":      "46494C",
			"date":       "E76F51",
			"text":       "577399",
		},
	}, nil
}

// newMessageHandler returns an InputHandler that handles outgoing messages.
func (cc *chatClient) newMessageHandler(outCh chan<- string) InputHandler {
	handler := func(message string) {
		cc.mu.RLock()
		outCh <- message
		cc.mu.RUnlock()
	}

	return handler
}

// updateChatBox updates chatBox component with incoming messages.
func (cc *chatClient) updateChatBox(inCh <-chan string, app *tview.Application,
	chatBox *tview.TextView) {

	for in := range inCh {
		s, err := lextwt.ParseSalty(in)
		if err != nil {
			continue
		}

		switch s := s.(type) {

		case *lextwt.SaltyEvent:
			// Ignored for now

		case *lextwt.SaltyText:
			if s.User.String() != cc.me.String() && s.User.String() != cc.user {
				continue
			}

			buf := &bytes.Buffer{}

			f := formatter.Formatter{
				Writer: buf,
				Indent: []byte(">  "),
				Width:  80,
			}

			if _, err := f.Write([]byte(s.LiteralText())); err != nil {
				log.WithError(err).Error("error formatting message")
				continue
			}

			cc.mu.RLock()
			app.QueueUpdateDraw(func() {
				fmt.Fprintf(chatBox,
					"[#%s]%s [#%x]%s\n[#%s]%s\n\n",
					cc.palette["date"],
					s.Timestamp.DateTime().Local().Format(dateTimeFormat),
					getUserColor(s.User.String()).Hex(),
					s.User.String(),
					cc.palette["text"],
					buf.String(),
				)
			})
			cc.mu.RUnlock()
		}
	}
}

// setScreen initializes the layout and UI components.
func (cc *chatClient) SetScreen(inCh <-chan string, outCh chan<- string) {
	app := tview.NewApplication()

	title := fmt.Sprintf(
		"Chatting as %s via %s/%s with %s via %s",
		cc.me, cc.uri, cc.inbox, cc.user, cc.config.Endpoint,
	)

	// Generate UI components.
	cc.mu.RLock()
	chatBox := NewChatBox(cc.palette, title)
	inputField := NewChatInput(cc.palette, cc.newMessageHandler(outCh))
	cc.mu.RUnlock()

	// Layout the widgets in flex view.
	flex := tview.NewFlex().SetDirection(tview.FlexRow).
		AddItem(chatBox, 0, 1, false).
		AddItem(inputField, 3, 0, true)

	go cc.updateChatBox(inCh, app, chatBox)

	err := app.SetRoot(flex, true).SetFocus(inputField).EnableMouse(true).Run()
	if err != nil {
		log.Fatal(err)
	}
}

// Open bi-directional stream between client and server.
func (cc *chatClient) RunChat(inCh chan<- string, outCh <-chan string) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// Receives incoming messages on a separate goroutine to be non-blocking.
	go func() {
		for msg := range Read(ctx, cc.key, cc.uri, cc.inbox, "", "") {
			inCh <- msg
		}
	}()

	// Forward/send outgoing messages.
	for msg := range outCh {
		if strings.TrimSpace(msg) == "" {
			continue
		}

		packedMsg := PackMessage(cc.me, msg)
		b, err := salty.Encrypt(cc.key, packedMsg, []string{cc.config.Key})
		if err != nil {
			log.Fatalf("error encrypting message: %v", err)
		}

		err = Send(cc.config.Endpoint, string(b))
		if err != nil {
			log.Fatalf("error sending message: %v", err)
		}

		inCh <- string(packedMsg)
	}
}