From bb01c11859f5e413299452bd9f9b82c4d31ba8e2 Mon Sep 17 00:00:00 2001
From: Garritt McCune <glmccune@gmail.com>
Date: Wed, 8 Sep 2021 14:52:48 -0500
Subject: [PATCH] Added a more RESTful interface for the category enities.

---
 cmd/inv/main.go | 110 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 105 insertions(+), 5 deletions(-)

diff --git a/cmd/inv/main.go b/cmd/inv/main.go
index 800ae56..dda7e23 100644
--- a/cmd/inv/main.go
+++ b/cmd/inv/main.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"strconv"
 	"time"
 
 	_ "github.com/lib/pq"
@@ -39,6 +40,7 @@ type Subcategory struct {
 
 func main() {
 	http.HandleFunc("/categories", categories)
+	http.HandleFunc("/category", category)
 	err := http.ListenAndServe(":8080", nil)
 
 	if err != nil {
@@ -51,14 +53,102 @@ func categories(w http.ResponseWriter, r *http.Request) {
 	switch r.Method {
 	case "GET":
 		getCategories(w, r)
-	case "POST":
-		insertCategory(w, r)
 	default:
 		w.WriteHeader(http.StatusMethodNotAllowed)
 		w.Write([]byte("Method not allowed"))
 	}
 }
 
+func category(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case "GET":
+		getCategory(w, r)
+	case "POST":
+		insertCategory(w, r)
+	case "DELETE":
+		deleteCategory(w, r)
+	default:
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		w.Write([]byte("Method not allowed"))
+	}
+}
+
+func getCategory(w http.ResponseWriter, r *http.Request) {
+	id := r.URL.Query().Get("id")
+
+	value, err := strconv.ParseInt(id, 0, 64)
+
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		w.Write([]byte(err.Error()))
+		return
+	}
+
+	psqlInfo := fmt.Sprintf("host=%s port=%d user=%s dbname=%s sslmode=disable", "localhost", 5432, "postgres", "inv")
+	db, err := sql.Open("postgres", psqlInfo)
+
+	if err != nil {
+		panic(err)
+	}
+
+	defer db.Close()
+
+	var category Category
+
+	if err := db.QueryRow("SELECT * FROM category WHERE category_id = $1;", value).Scan(&category.Id, &category.Name); err != nil {
+		if err == sql.ErrNoRows {
+			w.Write([]byte("No rows found"))
+			return
+		}
+
+		w.Write([]byte(err.Error()))
+		return
+	}
+
+	jsonBytes, err := json.Marshal(&category)
+
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+	w.Write(jsonBytes)
+}
+
+func deleteCategory(w http.ResponseWriter, r *http.Request) {
+	id := r.URL.Query().Get("id")
+
+	value, err := strconv.ParseInt(id, 0, 64)
+
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		w.Write([]byte(err.Error()))
+		return
+	}
+
+	psqlInfo := fmt.Sprintf("host=%s port=%d user=%s dbname=%s sslmode=disable", "localhost", 5432, "postgres", "inv")
+	db, err := sql.Open("postgres", psqlInfo)
+
+	if err != nil {
+		panic(err)
+	}
+
+	defer db.Close()
+
+	_, err = db.Exec("DELETE FROM category WHERE category_id = $1;", value)
+
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		w.Write([]byte(err.Error()))
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+	w.Write([]byte(fmt.Sprintf("Deleted category '%d'.", value)))
+}
+
 func getCategories(w http.ResponseWriter, r *http.Request) {
 	//Note: The postgres driver seems to get confused when no password is supplied, so omit it in the connection sting.
 	//https://rajyavardhan.medium.com/when-you-get-relation-does-not-exist-in-postgres-7ffb0c3c674b
@@ -104,6 +194,14 @@ func getCategories(w http.ResponseWriter, r *http.Request) {
 }
 
 func insertCategory(w http.ResponseWriter, r *http.Request) {
+	ct := r.Header.Get("content-type")
+
+	if ct != "application/json" {
+		w.WriteHeader(http.StatusUnsupportedMediaType)
+		w.Write([]byte(fmt.Sprintf("Unsupported media type '%s'", ct)))
+		return
+	}
+
 	bodyBytes, err := ioutil.ReadAll(r.Body)
 
 	if err != nil {
@@ -112,6 +210,8 @@ func insertCategory(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	defer r.Body.Close()
+
 	var category Category
 
 	err = json.Unmarshal(bodyBytes, &category)
@@ -127,13 +227,13 @@ func insertCategory(w http.ResponseWriter, r *http.Request) {
 
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
-		w.Write([]byte("Failed to connect to the DB"))
+		w.Write([]byte(err.Error()))
 		return
 	}
 
 	id := 0
 
-	err = db.QueryRow("INSERT INTO category (category_name) VALUES ($1) RETURNING category_id", category.Name).Scan(&id)
+	err = db.QueryRow("INSERT INTO category (category_name) VALUES ($1) RETURNING category_id;", category.Name).Scan(&id)
 
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
@@ -142,5 +242,5 @@ func insertCategory(w http.ResponseWriter, r *http.Request) {
 	}
 
 	w.WriteHeader(http.StatusOK)
-	w.Write([]byte(fmt.Sprint("New Record: ", id)))
+	w.Write([]byte(fmt.Sprintf("New Record: %d", id)))
 }