package main

import (
	"bytes"
	"encoding/base64"
	"image"
	"image/color"
	_ "image/gif"
	"image/jpeg"
	_ "image/png"
	"io/ioutil"
	"log"
	"math/rand"
	"os"
	"strings"
	"unicode"

	"time"

	"github.com/golang/freetype"
	"github.com/hamcha/clessy/tg"
	"github.com/llgcode/draw2d"
	"github.com/llgcode/draw2d/draw2dimg"
)

var snapFontData draw2d.FontData

func initsnapchat() {
	rand.Seed(time.Now().Unix())

	fontfile, err := os.Open(*sourcesans)
	assert(err)
	defer fontfile.Close()

	bytes, err := ioutil.ReadAll(fontfile)
	assert(err)

	font, err := freetype.ParseFont(bytes)
	assert(err)

	snapFontData = draw2d.FontData{"sourcesans", draw2d.FontFamilySans, draw2d.FontStyleBold}
	draw2d.RegisterFont(snapFontData, font)

	log.Println("[snapchat] Loaded!")
}

func snapchat(broker *tg.Broker, update tg.APIMessage) {
	// Make replies work
	if update.ReplyTo != nil && update.Text != nil && update.ReplyTo.Photo != nil {
		update.Photo = update.ReplyTo.Photo
		update.Caption = update.Text
	}

	if update.Photo != nil && update.Caption != nil {
		caption := *(update.Caption)
		if strings.HasPrefix(caption, "/snap ") && len(caption) > 6 {
			txt := strings.TrimSpace(caption[6:])

			maxsz := 0
			photo := tg.APIPhotoSize{}
			for _, curphoto := range update.Photo {
				if curphoto.Width > maxsz {
					maxsz = curphoto.Width
					photo = curphoto
				}
			}

			broker.GetFile(photo.FileID, func(broker *tg.Broker, data tg.BrokerUpdate) {
				if data.Type == tg.BError {
					log.Printf("[snapchat] Received error from broker: %s\n", *data.Error)
					broker.SendTextMessage(update.Chat, "<b>ERRORE!</b> @hamcha controlla la console!", &update.MessageID)
					return
				}

				pbytes, err := base64.StdEncoding.DecodeString(*data.Bytes)
				if err != nil {
					log.Printf("[snapchat] Base64 decode error: %s\n", err.Error())
					broker.SendTextMessage(update.Chat, "<b>ERRORE!</b> @hamcha controlla la console!", &update.MessageID)
					return
				}

				img, _, err := image.Decode(bytes.NewReader(pbytes))
				if err != nil {
					log.Printf("[snapchat] Image decode error: %s\n", err.Error())
					broker.SendTextMessage(update.Chat, "<b>ERROR</b>: Non riesco a leggere l'immagine", &update.MessageID)
					return
				}

				broker.SendChatAction(update.Chat, tg.ActionUploadingPhoto)

				// Create target image
				bounds := img.Bounds()
				iwidth := float64(bounds.Size().Y) / 1.6
				iheight := float64(bounds.Size().Y)

				repos := iwidth < float64(bounds.Size().X)
				if !repos {
					iwidth = float64(bounds.Size().X)
				}

				timg := image.NewRGBA(image.Rect(0, 0, int(iwidth), int(iheight)))
				gc := draw2dimg.NewGraphicContext(timg)
				gc.SetFontData(snapFontData)

				gc.Save()
				if repos {
					gc.Translate(-(float64(bounds.Size().X)-iwidth)/2, 0)
				}
				gc.DrawImage(img)
				gc.Restore()

				scale := iwidth / 25
				gc.SetFontSize(scale)

				lineMargin := scale / 3
				boxMargin := lineMargin
				topMargin := lineMargin / 6
				write := func(text string, startHeight float64) {
					texts := wordWrap(gc, strings.TrimSpace(text), iwidth*0.9)
					totalHeight := startHeight
					firstLine := 0.
					for _, txt := range texts {
						_, top, _, bottom := gc.GetStringBounds(txt)
						height := (bottom - top)
						if firstLine == 0 {
							firstLine = height
						}
						totalHeight += lineMargin + height
					}

					// Draw background
					starty := startHeight - boxMargin - topMargin - firstLine
					endy := totalHeight + boxMargin - firstLine
					gc.Save()
					gc.SetFillColor(color.RGBA{0, 0, 0, 160})
					gc.BeginPath()
					gc.MoveTo(0, starty)
					gc.LineTo(iwidth, starty)
					gc.LineTo(iwidth, endy)
					gc.LineTo(0, endy)
					gc.Close()
					gc.Fill()
					gc.Restore()

					// Write lines
					gc.SetFillColor(image.White)
					height := startHeight
					for _, txt := range texts {
						left, top, right, bottom := gc.GetStringBounds(txt)
						width := right - left
						gc.FillStringAt(txt, (iwidth-width)/2, height)
						height += lineMargin + (bottom - top)
					}
				}
				write(txt, (rand.Float64()*0.4+0.3)*iheight)

				buf := new(bytes.Buffer)
				err = jpeg.Encode(buf, timg, &(jpeg.Options{Quality: 80}))
				if err != nil {
					log.Printf("[snapchat] Image encode error: %s\n", err.Error())
					broker.SendTextMessage(update.Chat, "<b>ERRORE!</b> @hamcha controlla la console!", &update.MessageID)
					return
				}
				broker.SendPhoto(update.Chat, buf.Bytes(), "meme.jpg", "", &update.MessageID)
			})
		}
	}
}

// Word wrapping code from https://github.com/fogleman/gg
// Copyright (C) 2016 Michael Fogleman
// Licensed under MIT (https://github.com/fogleman/gg/blob/master/LICENSE.md)

func splitOnSpace(x string) []string {
	var result []string
	pi := 0
	ps := false
	for i, c := range x {
		s := unicode.IsSpace(c)
		if s != ps && i > 0 {
			result = append(result, x[pi:i])
			pi = i
		}
		ps = s
	}
	result = append(result, x[pi:])
	return result
}

func wordWrap(gc draw2d.GraphicContext, s string, width float64) []string {
	var result []string
	for _, line := range strings.Split(s, "\n") {
		fields := splitOnSpace(line)
		if len(fields)%2 == 1 {
			fields = append(fields, "")
		}
		x := ""
		for i := 0; i < len(fields); i += 2 {
			left, _, right, _ := gc.GetStringBounds(x + fields[i])
			w := right - left
			if w > width {
				if x == "" {
					result = append(result, fields[i])
					x = ""
					continue
				} else {
					result = append(result, x)
					x = ""
				}
			}
			x += fields[i] + fields[i+1]
		}
		if x != "" {
			result = append(result, x)
		}
	}
	for i, line := range result {
		result[i] = strings.TrimSpace(line)
	}
	return result
}