Add api for annotations

this only returns the first available annotation for now
annotation content is returned in html format, so it can easily be
inserted in the frontend

displaying the annotation in the frontend is still a TODO

annotations.go

@@ -0,0 +1,104 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"regexp"
+	"strings"
+
+	"github.com/gorilla/mux"
+)
+
+type annotationsResponse struct {
+	Response struct {
+		Referent struct {
+			Annotations []struct {
+				Body struct {
+					Html string `json:"html"`
+				} `json:"body"`
+			} `json:"annotations"`
+		} `json:"referent"`
+	} `json:"response"`
+}
+
+func annotationsHandler(w http.ResponseWriter, r *http.Request) {
+	id := mux.Vars(r)["id"]
+	url := fmt.Sprintf("https://genius.com/api/referents/%s?text_format=html", id)
+	resp, err := sendRequest(url)
+
+	if err != nil {
+		logger.Errorln(err)
+		w.WriteHeader(http.StatusInternalServerError)
+		render("error", w, map[string]string{
+			"Status": "500",
+			"Error":  "cannot reach genius servers",
+		})
+		return
+	}
+
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusNotFound {
+		w.WriteHeader(http.StatusNotFound)
+		render("error", w, map[string]string{
+			"Status": "404",
+			"Error":  "page not found",
+		})
+		return
+	}
+
+	buf := new(bytes.Buffer)
+	_, err = buf.ReadFrom(resp.Body)
+	if err != nil {
+		logger.Errorln("Error paring genius api response", err)
+		w.WriteHeader(http.StatusInternalServerError)
+		render("error", w, map[string]string{
+			"Status": "500",
+			"Error":  "Parsing error",
+		})
+		return
+	}
+
+	var data annotationsResponse
+	err = json.Unmarshal(buf.Bytes(), &data)
+	if err != nil {
+		logger.Errorf("could not unmarshal json: %s\n", err)
+		w.WriteHeader(http.StatusInternalServerError)
+		render("error", w, map[string]string{
+			"Status": "500",
+			"Error":  "Could not parse genius api response",
+		})
+		return
+	}
+
+	w.Header().Set("content-type", "application/json")
+	body := data.Response.Referent.Annotations[0].Body
+	body.Html = cleanBody(body.Html)
+	response, err := json.Marshal(body)
+
+	if err != nil {
+		logger.Errorf("could not marshal json: %s\n", err)
+		w.WriteHeader(http.StatusInternalServerError)
+		render("error", w, map[string]string{
+			"Status": "500",
+			"Error":  "Could not parse genius api response",
+		})
+		return
+	}
+
+	_, err = w.Write(response)
+	if err != nil {
+		logger.Errorln("Error sending response: ", err)
+	}
+}
+
+func cleanBody(body string) string {
+	var withCleanedImageLinks = strings.Replace(body, "https://images.rapgenius.com/", "/images/", -1)
+
+	var re = regexp.MustCompile(`https?:\/\/[a-z]*.?genius.com`)
+	var withCleanedLinks = re.ReplaceAllString(withCleanedImageLinks, "")
+
+	return withCleanedLinks
+}

main.go

@@ -29,6 +29,7 @@ func main() {
 	r.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { render("home", w, nil) })
 	r.HandleFunc("/search", searchHandler).Methods("GET")
 	r.HandleFunc("/{id}-lyrics", lyricsHandler)
+	r.HandleFunc("/{id}/{artist-song}/{verse}/annotations", annotationsHandler)
 	r.HandleFunc("/images/{filename}.{ext}", proxyHandler)
 	r.PathPrefix("/static/").Handler(http.StripPrefix("/static/", http.FileServer(http.Dir("static"))))
 	r.NotFoundHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

static/script.js

@@ -14,6 +14,17 @@ document.querySelectorAll("#lyrics a").forEach(item => {
 
 function getAnnotation(e) {
 	e.preventDefault()
-	//const uri = e.target.parentElement.getAttribute("href")
-	console.log("Annotations are not yet implemented!")
+	const uri = e.target.parentElement.getAttribute("href")
+	console.log("Annotations are not yet implemented!", uri)
+
+	xhr = new XMLHttpRequest()
+	xhr.open("GET", uri + "/annotations")
+	xhr.send()
+	xhr.onreadystatechange = function() {
+		if (this.readyState == 4 && this.status == 200) {
+			json = JSON.parse(this.responseText)
+			alert(json.html)
+			// TODO: display annotations properly
+		}
+	}
 }