discordBots/cmd/dealsbot/api/gog.go

package api

import (
	"fmt"
	"golang.org/x/net/html"
	"log/slog"
	"net/http"
	"regexp"
)

type GogStruct struct {
	url      string
	baseUrl  string
	idPrefix string
	headers  map[string]string
	deals    DealsMap
	logger   *slog.Logger
}

func NewGogApi(logger *slog.Logger) GogStruct {
	gog := GogStruct{
		url:      "https://www.gog.com/en/games?priceRange=0,0&discounted=true",
		baseUrl:  "https://www.gog.com/game/",
		idPrefix: "gog-",
		headers:  make(map[string]string),
		deals:    make(map[string]Deal),
		logger:   logger,
	}
	gog.headers["Accept-Language"] = "en"
	gog.headers["User-Agent"] = "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:93.0) Gecko/20100101 Firefox/93.0"
	return gog
}

func (e GogStruct) Load() error {
	client := &http.Client{}
	// might have to add a cookie at a later time but currently works without
	// "Cookie", "gog_lc=GB_GBP_en-US" or "Accept-Language", "en"
	reqStore, err := http.NewRequest("GET", e.url, nil)
	if err != nil {
		return err
	}

	for key, value := range e.headers {
		reqStore.Header.Set(key, value)
	}

	resStore, err := client.Do(reqStore)
	if err != nil {
		return err
	}
	bodyStore := html.NewTokenizer(resStore.Body)

	regexAppid, err := regexp.Compile(`/\w{2}/game/([-\w]+)`)
	if err != nil {
		return err
	}

	var appIDs []string
	func() {
		for {
			tt := bodyStore.Next()

			switch {
			case tt == html.ErrorToken:
				// file end or error
				return
			case tt == html.StartTagToken:
				t := bodyStore.Token()
				if t.Data != "a" { // only <a> tag
					continue
				}
				for _, a := range t.Attr {
					if !(a.Key == "class" && a.Val == "product-tile product-tile--grid") {
						continue
					}
					for _, attr := range t.Attr {
						if attr.Key != "href" {
							continue
						}
						appID := regexAppid.FindStringSubmatch(attr.Val)
						if len(appID) < 1 {
							continue
						}
						appIDs = append(appIDs, appID[1])
					}
				}
			}
		}
	}()

	for _, appID := range appIDs {
		reqGame, err := http.NewRequest("GET", fmt.Sprintf("%v%v", e.baseUrl, appID), nil)
		if err != nil {
			return err
		}

		for key, value := range e.headers {
			reqGame.Header.Set(key, value)
		}

		resGame, err := client.Do(reqGame)
		if err != nil {
			return err
		}
		bodyGame := html.NewTokenizer(resGame.Body)

		title, image := gogParseMeta(bodyGame)
		url := fmt.Sprintf("%v%v", e.baseUrl, appID)
		id := fmt.Sprintf("%v%v", e.idPrefix, appID)
		e.deals[id] = Deal{
			Id:    id,
			Title: title,
			Url:   url,
			Image: image,
		}
	}

	return nil
}

func gogParseMeta(htmlBody *html.Tokenizer) (string, string) {
	var title, image string
	func() {
		for {
			tt := htmlBody.Next()

			switch {
			case tt == html.ErrorToken:
				// file end or error
				return
			case tt == html.StartTagToken:
				t := htmlBody.Token()
				if t.Data != "meta" {
					continue
				}
				for _, a := range t.Attr {
					if a.Key == "property" && a.Val == "og:title" {
						for _, c := range t.Attr {
							if c.Key == "content" {
								title = c.Val
							}
						}
					}
					if a.Key == "property" && a.Val == "og:image" {
						for _, c := range t.Attr {
							if c.Key == "content" {
								image = c.Val
							}
						}
					}
				}
				if title != "" && image != "" {
					return
				}
			}
		}
	}()
	return title, image
}

func (e GogStruct) Get() []Deal {
	var deals []Deal
	for _, deal := range e.deals {
		deals = append(deals, deal)
	}
	return deals
}