GHC 2020 - Golang Workshop

main.go

// Grace Hopper Convention 2020 - Microservice example for beginner Go workshop
// Contains a basic microservice using Go standard library, suggestions for
// features to work on and bug(s) for participants to find.

package main

import (
	"fmt"
	"log"
	"net/http"
	"strings"
)

// Start running the microservice with our endpoints
func main() {
	stats := make(map[string]int)

	// ** Potential Feature: const statsAPIBase = "/stats/" e.g. /stats/angry
	http.Handle("/emoji/", &EmojiHandler{stats})
	http.Handle("/count", &CountEmojiHandler{stats})

	port := ":8080"
	fmt.Println("Serving on port", port)
	log.Fatal(http.ListenAndServe(port, nil))
}

// EmojiHandler handles emoji API requests. Given an string for an emoji, returns the
// emoji icon. It is an implementation of the `net/http` standard library interface
// Handler which must implement `ServeHTTP`
type EmojiHandler struct {
	stats map[string]int
}

// ServeHTTP serves the emoji endpoint
// ** Potential Feature: support more emojis e.g. /emoji/sad, /emoji/smile
func (e *EmojiHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	log.Println("Request:", r.URL.Path)
	param := strings.TrimPrefix(r.URL.Path, "/emoji/")

	if param == "angry" {
		angryCount := e.stats["angry"]
		angryCount++
		fmt.Fprintln(w, "😠")
		return
	}

	http.Error(w, http.StatusText(http.StatusNotImplemented), http.StatusNotImplemented)
}

// CountEmojiHandler handles counts succesful emoji API requests. Returns the number of requests that have
// been made to the emoji API
type CountEmojiHandler struct {
	stats map[string]int
}

// ServeHTTP serves the count endpoint
func (c *CountEmojiHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	log.Println("Request:", r.URL.Path)

	count := 0
	for key, value := range c.stats {
		count := count + value
		log.Println("key:", key, " value:", value, " count:", count)
	}
	fmt.Fprintln(w, count)
}