//
// WRP - Web Rendering Proxy
//
// Copyright (c) 2013-2024 Antoni Sawicki
// Copyright (c) 2019-2024 Google LLC
//

package main

import (
	"bytes"
	"context"
	"embed"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"runtime"
	"strconv"
	"strings"
	"syscall"
	"text/template"
	"time"
)

const version = "4.8.0"

var (
	addr       = flag.String("l", ":8080", "Listen address:port, default :8080")
	headless   = flag.Bool("h", true, "Headless mode / hide browser window (default true)")
	noDel      = flag.Bool("n", false, "Do not free maps and images after use")
	defType    = flag.String("t", "gif", "Image type: png|gif|jpg")
	wrpMode    = flag.String("m", "ismap", "WRP Mode: ismap|html")
	defImgSize = flag.Int64("is", 200, "html mode default image size")
	defJpgQual = flag.Int64("q", 75, "Jpeg image quality, default 75%") // TODO: this should be form dropdown when jpeg is selected as image type
	fgeom      = flag.String("g", "1152x600x216", "Geometry: width x height x colors, height can be 0 for unlimited")
	htmFnam    = flag.String("ui", "wrp.html", "HTML template file for the UI")
	delay      = flag.Duration("s", 2*time.Second, "Delay/sleep after page is rendered and before screenshot is taken")
	userAgent  = flag.String("ua", "", "override chrome user agent")
)

var (
	srv         http.Server
	actx, ctx   context.Context
	acncl, cncl context.CancelFunc
	img         = make(map[string]bytes.Buffer)
	ismap       = make(map[string]wrpReq)
	defGeom     geom
	htmlTmpl    *template.Template
)

//go:embed *.html
var fs embed.FS

type geom struct {
	w int64
	h int64
	c int64
}

// TODO: there is a major overlap/duplication/triplication
// between the 3 data structs, perhps we could reduce to just one?

// Data for html template
type uiData struct {
	Version    string
	WrpMode    string
	URL        string
	BgColor    string
	NColors    int64
	JQual      int64
	Width      int64
	Height     int64
	Zoom       float64
	ImgType    string
	ImgURL     string
	ImgSize    string
	ImgWidth   int
	ImgHeight  int
	MaxSize    int64
	MapURL     string
	PageHeight string
	TeXT       string
}

// Parameters for HTML print function
type uiParams struct {
	bgColor    string
	pageHeight string
	imgSize    string
	imgURL     string
	mapURL     string
	imgWidth   int
	imgHeight  int
	text       string
}

// WRP Request
type wrpReq struct {
	url     string
	width   int64
	height  int64
	zoom    float64
	nColors int64
	jQual   int64
	mouseX  int64
	mouseY  int64
	keys    string
	buttons string
	imgType string
	wrpMode string
	maxSize int64
	w       http.ResponseWriter
	r       *http.Request
}

func (rq *wrpReq) parseForm() {
	rq.r.ParseForm()
	rq.wrpMode = rq.r.FormValue("m")
	if rq.wrpMode == "" {
		rq.wrpMode = *wrpMode
	}
	rq.url = rq.r.FormValue("url")
	if len(rq.url) > 1 && !strings.HasPrefix(rq.url, "http") {
		rq.url = fmt.Sprintf("http://www.google.com/search?q=%s", url.QueryEscape(rq.url))
	}
	// TODO: implement atoiOrZero
	rq.width, _ = strconv.ParseInt(rq.r.FormValue("w"), 10, 64)
	rq.height, _ = strconv.ParseInt(rq.r.FormValue("h"), 10, 64)
	if rq.width < 10 && rq.height < 10 {
		rq.width = defGeom.w
		rq.height = defGeom.h
	}
	rq.zoom, _ = strconv.ParseFloat(rq.r.FormValue("z"), 64)
	if rq.zoom < 0.1 {
		rq.zoom = 1.0
	}
	rq.imgType = rq.r.FormValue("t")
	switch rq.imgType {
	case "png", "gif", "jpg":
	default:
		rq.imgType = *defType
	}
	rq.nColors, _ = strconv.ParseInt(rq.r.FormValue("c"), 10, 64)
	if rq.nColors < 2 || rq.nColors > 256 {
		rq.nColors = defGeom.c
	}
	rq.jQual, _ = strconv.ParseInt(rq.r.FormValue("q"), 10, 64)
	if rq.jQual < 1 || rq.jQual > 100 {
		rq.jQual = *defJpgQual
	}
	rq.keys = rq.r.FormValue("k")
	rq.buttons = rq.r.FormValue("Fn")
	rq.maxSize, _ = strconv.ParseInt(rq.r.FormValue("s"), 10, 64)
	if rq.maxSize == 0 {
		rq.maxSize = *defImgSize
	}
	log.Printf("%s WrpReq from UI Form: %+v\n", rq.r.RemoteAddr, rq)
}

func (rq *wrpReq) printUI(p uiParams) {
	rq.w.Header().Set("Cache-Control", "max-age=0")
	rq.w.Header().Set("Expires", "-1")
	rq.w.Header().Set("Pragma", "no-cache")
	rq.w.Header().Set("Content-Type", "text/html")
	if p.bgColor == "" {
		p.bgColor = "#FFFFFF"
	}
	data := uiData{
		Version:    version,
		WrpMode:    rq.wrpMode,
		URL:        rq.url,
		BgColor:    p.bgColor,
		Width:      rq.width,
		Height:     rq.height,
		NColors:    rq.nColors,
		JQual:      rq.jQual,
		Zoom:       rq.zoom,
		MaxSize:    rq.maxSize,
		ImgType:    rq.imgType,
		ImgSize:    p.imgSize,
		ImgWidth:   p.imgWidth,
		ImgHeight:  p.imgHeight,
		ImgURL:     p.imgURL,
		MapURL:     p.mapURL,
		PageHeight: p.pageHeight,
		TeXT:       p.text,
	}
	err := htmlTmpl.Execute(rq.w, data)
	if err != nil {
		fmt.Fprintf(rq.w, "Error: %v", err)
	}
}

func pageServer(w http.ResponseWriter, r *http.Request) {
	log.Printf("%s Page Request for %s [%+v]\n", r.RemoteAddr, r.URL.Path, r.URL.RawQuery)
	rq := wrpReq{
		r: r,
		w: w,
	}
	rq.parseForm()
	if len(rq.url) < 4 {
		rq.printUI(uiParams{bgColor: "#FFFFFF"})
		return
	}
	rq.navigate() // TODO: if error from navigate do not capture
	if rq.wrpMode == "html" {
		rq.captureMarkdown()
		return
	}
	rq.captureScreenshot()
}

func haltServer(w http.ResponseWriter, r *http.Request) {
	log.Printf("%s Shutdown Request for %s\n", r.RemoteAddr, r.URL.Path)
	w.Header().Set("Content-Type", "text/plain")
	fmt.Fprintf(w, "Shutting down WRP...\n")
	w.(http.Flusher).Flush()
	time.Sleep(time.Second * 2)
	cncl()
	acncl()
	srv.Shutdown(context.Background())
	os.Exit(1)
}

func wrpTemplate(t string) string {
	var tmpl []byte
	fh, err := os.Open(t)
	if err != nil {
		goto builtin
	}
	defer fh.Close()

	tmpl, err = io.ReadAll(fh)
	if err != nil {
		goto builtin
	}
	log.Printf("Got HTML UI template from %v file, size %v \n", t, len(tmpl))
	return string(tmpl)

builtin:
	fhs, err := fs.Open("wrp.html")
	if err != nil {
		log.Fatal(err)
	}
	defer fhs.Close()

	tmpl, err = io.ReadAll(fhs)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("Got HTML UI template from embed\n")
	return string(tmpl)
}

func main() {
	var err error
	log.SetFlags(log.LstdFlags | log.Lshortfile)
	flag.Parse()
	log.Printf("Web Rendering Proxy Version %s (%v)\n", version, runtime.GOARCH)
	log.Printf("Args: %q", os.Args)
	if len(os.Getenv("PORT")) > 0 {
		*addr = ":" + os.Getenv(("PORT"))
	}
	printMyIPs(*addr)
	n, err := fmt.Sscanf(*fgeom, "%dx%dx%d", &defGeom.w, &defGeom.h, &defGeom.c)
	if err != nil || n != 3 {
		log.Fatalf("Unable to parse -g geometry flag / %s", err)
	}

	cncl, acncl = chromedpStart()
	defer cncl()
	defer acncl()

	c := make(chan os.Signal)
	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
	go func() {
		<-c
		log.Printf("Interrupt - shutting down.")
		cncl()
		acncl()
		srv.Shutdown(context.Background())
		os.Exit(1)
	}()

	http.HandleFunc("/", pageServer)
	http.HandleFunc("/map/", mapServer)
	http.HandleFunc("/img/", imgServerMap)
	http.HandleFunc(imgZpfx, imgServerTxt)
	http.HandleFunc("/shutdown/", haltServer)
	http.HandleFunc("/favicon.ico", http.NotFound)

	log.Printf("Default Img Type: %v, Geometry: %+v", *defType, defGeom)

	htmlTmpl, err = template.New("wrp.html").Parse(wrpTemplate(*htmFnam))
	if err != nil {
		log.Fatal(err)
	}

	log.Print("Starting WRP http server")
	srv.Addr = *addr
	err = srv.ListenAndServe()
	if err != nil {
		log.Fatal(err)
	}
}