add evaluator

.drone.yml

@@ -19,3 +19,14 @@ steps:
       target: /bangs/
       path_style: true
       endpoint: https://s3.sbruder.de
+
+  - name: docker
+    image: plugins/docker
+    settings:
+      registry: r.sbruder.de
+      username:
+        from_secret: docker_username
+      password:
+        from_secret: docker_password
+      repo: r.sbruder.de/bang-evaluator
+      cache_from: r.sbruder.de/bang-evaluator

Dockerfile

@@ -0,0 +1,22 @@
+FROM golang:alpine as builder
+
+WORKDIR /go/src/git.sbruder.de/simon/bangs/evaluator/
+
+COPY evaluator/evaluator.go .
+
+RUN apk add --no-cache git upx
+
+RUN go get -v \
+    && CGO_ENABLED=0 go build -v -ldflags="-s -w" \
+    && upx --ultra-brute evaluator
+
+FROM scratch
+
+COPY --from=builder /go/src/git.sbruder.de/simon/bangs/evaluator/evaluator /evaluator
+copy bangs.json /bangs.json
+
+USER 1000
+
+ENTRYPOINT ["/evaluator"]
+
+EXPOSE 8081

evaluator/evaluator.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"net/http"
+	"log"
+	"strings"
+	"encoding/json"
+	"io/ioutil"
+	"regexp"
+)
+
+var bangs = loadBangs()
+
+func main() {
+	http.HandleFunc("/eval", func(w http.ResponseWriter, r *http.Request) {
+		searchQuery := r.URL.Query().Get("query")
+		searchEngine := r.URL.Query().Get("engine")
+
+		if (searchQuery == "" || searchEngine == "") {
+			http.Error(w, "400 Bad Request", http.StatusBadRequest)
+			return
+		}
+
+		searchQuery, searchEngine = evaluateBang(searchQuery, searchEngine)
+
+		searchURL := buildSearchURL(searchEngine, searchQuery)
+		http.Redirect(w, r, searchURL, http.StatusSeeOther)
+	})
+
+	log.Fatalf("Failed to start http server: %v", http.ListenAndServe(":8081", nil))
+}
+
+func loadBangs() (bangs map[string]string) {
+	data, err := ioutil.ReadFile("bangs.json")
+    if err != nil {
+		log.Fatalf("Failed to read bangs: %v", err)
+	}
+
+	err = json.Unmarshal(data, &bangs)
+	if err != nil {
+		log.Fatalf("Failed to decode bangs: %v", err)
+	}
+
+	return
+}
+
+func buildSearchURL(template string, query string) (searchUrl string) {
+	return strings.Replace(template, "%s", query, 1)
+}
+
+func parseBang(searchQuery string) (bang string, query string) {
+	regexStartBang, _ := regexp.Compile("\\!(.*) (.*)")
+	regexEndBang, _ := regexp.Compile("(.*) \\!(.*)")
+
+	startBang := regexStartBang.FindSubmatch([]byte(searchQuery))
+	endBang := regexEndBang.FindSubmatch([]byte(searchQuery))
+
+	if len(endBang) == 3 {
+		return string(endBang[2]), string(endBang[1])
+	} else if len(startBang) == 3 {
+		return string(startBang[1]), string(startBang[2])
+	} else {
+		return "", searchQuery
+	}
+}
+
+func evaluateBang(searchQuery string, searchEngine string) (query string, engine string) {
+	bang, query := parseBang(searchQuery)
+
+	return query, bangs[bang]
+}