package main

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

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


type Author struct {
	Firstname       string  `json:"firstname"`
	Lastname        string  `json:"lastname"`
}

// 初始化book的切片
var books []Book

func main()  {
	// 初始化路由
	r := mux.NewRouter()

	// 增加mock数据
	books = append(books, Book{ID: "1", Isbn: "448743", Title: "Go语言", Author: &Author{Firstname: "John", Lastname: "Doe"}})
	books = append(books, Book{ID: "2", Isbn: "448744", Title: "Java语言", Author: &Author{Firstname: "Steve", Lastname: "Smith"}})
	books = append(books, Book{ID: "3", Isbn: "448745", Title: "java程序设计", Author: &Author{Firstname: "Steve", Lastname: "Smith"}})

	// 普通路由
	r.HandleFunc("/api/books", getBooks).Methods("GET")

	r.HandleFunc("/api2", getBooks).Methods("GET")
	r.HandleFunc("/api2/y", getBooks).Methods("GET")

	//子路由
	//http://127.0.0.1:8000/products/a
	s := r.PathPrefix("/products").Subrouter()
	s.HandleFunc("/a",getBooks)
	s.PathPrefix("/b").Subrouter().HandleFunc("/a",getBooks)

	// 普通路由参数
	//http://localhost:8000/api/books/2
	r.HandleFunc("/api/books/{id}", getBook).Methods("GET")

	//r.HandleFunc("/api/books/byTitle/{title}", getBookByTitle).Methods("GET")
	// 正则路由参数，title的查询限制为英文字母,并且是小写字母，否则报：404 page not found
	r.HandleFunc("/api/books/byTitle/{title:[a-z]+}", getBookByTitle).Methods("GET")

	r.HandleFunc("/api/books", createBook).Methods("POST")
	r.HandleFunc("/api/books/{id}", updateBook).Methods("PUT")
	r.HandleFunc("/api/books/{id}", deleteBook).Methods("DELETE")

	// 监听8000端口，并打出日志
	log.Fatal(http.ListenAndServe(":8000", r))
}

// 查询所有的Book
func getBooks(w http.ResponseWriter, r *http.Request){
	w.Header().Set("Content-Type","application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(books)
}

// 根据ID查询Book
func getBook(w http.ResponseWriter, r *http.Request){
	w.Header().Set("Content-Type","application/json")
	params := mux.Vars(r)  //map[string]string
	for _,item := range books {
		if item.ID == params["id"] {
			json.NewEncoder(w).Encode(item)
			w.WriteHeader(http.StatusOK)
			return
		}
	}
	w.WriteHeader(http.StatusNotFound)
	return
}

// 根据Title查询
func getBookByTitle(w http.ResponseWriter, r *http.Request) {
	var newBooks []Book
	params := mux.Vars(r) // Get params
	for _, item := range books {
		if strings.Contains(item.Title, params["title"]) {
			newBooks = append(newBooks, item)
		}
	}
	if len(newBooks) == 0 {
		w.WriteHeader(http.StatusNotFound)
		return
	}
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(newBooks)
	return
}

// 创建Book
func createBook(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(10000000)) // Mock ID - not safe
	books = append(books, book);
	json.NewEncoder(w).Encode(books)
}

// 修改Book
func updateBook(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r) // Get params
	var book Book
	json.NewDecoder(r.Body).Decode(&book)
	for index, item := range books {
		if item.ID == params["id"] {
			books[index] = book
			books[index].ID = item.ID
			break
		}
	}
	json.NewEncoder(w).Encode(books)
}

// 删除Book
func deleteBook(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r) // Get params
	for index, item := range books {
		if item.ID == params["id"] {
			books = append(books[:index], books[index+1:]...)
			break
		}
	}
	json.NewEncoder(w).Encode(books)
}