main.go

package main

import (
	"encoding/json"
	"github.com/gorilla/mux"
	"log"
	"math/rand"
	"net/http"
	"strconv"
)

// Init book var as a slice Book struct
var books []Book

// Book struct ( Model )
type Book struct {
	ID     string  `json:"id"`
	Isbn   string  `json:"isbn"`
	Title  string  `json:"title"`
	Author *Author `json:"author"`
}

// Author struct ( Model )
type Author struct {
	FirstName string `json:"first_name"`
	LastName  string `json:"last_name"`
}

// Get all books
func getBooks(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "Application/json")
	json.NewEncoder(w).Encode(books)
}

// Get a single book
func getBook(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "Application/json")

	// Get params
	params := mux.Vars(r)

	// Loop through books and find id
	for _, item := range books {
		if item.ID == params["id"] {
			json.NewEncoder(w).Encode(item)
			return
		}
	}
	json.NewEncoder(w).Encode(&Book{})

}

// Create a single book
func createBooks(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "Application/json")
	var book Book
	_ = json.NewDecoder(r.Body).Decode(&book)
	book.ID = strconv.Itoa(rand.Intn(1000000))
	books = append(books, book)
	json.NewEncoder(w).Encode(book)

}

// Update a single book
func updateBooks(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "Application/json")
	params:= mux.Vars(r)
	for index, item := range books {
		if item.ID == params["id"] {
			books = append(books[:index], books[index+1:]...)
			var book Book
			_ = json.NewDecoder(r.Body).Decode(&book)
			book.ID = params["id"]
			books = append(books, book)
			json.NewEncoder(w).Encode(book)
			return
		}
	}
	json.NewEncoder(w).Encode(books)

}

// Delete a single book
func deleteBooks(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "Application/json")
	params := mux.Vars(r)
	for index, item := range books {
		if item.ID == params["id"] {
			books = append(books[:index], books[index+1:]...)
			break
		}
	}
	json.NewEncoder(w).Encode(books)
}

func main() {
	// Init router
	r := mux.NewRouter()

	// Mock data
	// TODO implement Database
	books = append(books, Book{"1", "447541", "Everything I Never Told You",
		&Author{"Celeste", "Celeste"}})
	books = append(books, Book{"2", "447431", "Are You There, Vodka? It’s Me, Chelsea",
		&Author{"Chelsea", "Handler"}})
	books = append(books, Book{"3", "447001", "Love in the Time of Cholera",
		&Author{"Gabriel", "Márquez"}})

	// Route handlers
	r.HandleFunc("/api/books", getBooks).Methods("GET")
	r.HandleFunc("/api/books/{id}", getBook).Methods("GET")
	r.HandleFunc("/api/books", createBooks).Methods("POST")
	r.HandleFunc("/api/books/{id}", updateBooks).Methods("PUT")
	r.HandleFunc("/api/books/{id}", deleteBooks).Methods("DELETE")

	// Start the server
	log.Fatal(http.ListenAndServe(":8000", r))
}