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main.go
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main.go
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package main
import (
"database/sql"
"encoding/json"
"flag"
"fmt"
"log"
"math/rand"
"net/http"
"os"
"path"
"time"
"github.com/gorilla/mux"
_ "github.com/mattn/go-sqlite3"
)
func init() {
rand.Seed(time.Now().UnixNano())
}
var DB *sql.DB
type Item struct {
ID string `json:"id"`
Description string `json:"description"`
User string `json:"user,omitempty"`
}
type Error struct {
Error string `json:"error"`
}
func errorResponse(rw http.ResponseWriter, msg string, code int) {
rw.WriteHeader(code)
json.NewEncoder(rw).Encode(&Error{Error: msg})
return
}
func addHeaders(rw http.ResponseWriter) {
rw.Header().Add("Access-Control-Allow-Origin", "http://localhost:8080")
rw.Header().Add("Access-Control-Allow-Methods", "GET,PUT,POST,DELETE,OPTIONS")
rw.Header().Add("Access-Control-Allow-Headers", "Content-Type")
rw.Header().Add("Access-Control-Allow-Credentials", "true")
rw.Header().Add("Content-Type", "application/json")
}
func GetHandler(rw http.ResponseWriter, req *http.Request) {
addHeaders(rw)
if req.Method == "OPTIONS" {
return
}
tx, err := DB.Begin()
if err != nil {
log.Printf("Error begining transaction: %v", err)
errorResponse(rw, "internal error", 500)
return
}
defer tx.Rollback()
cur, err := tx.Query("SELECT * FROM items")
if err != nil {
log.Printf("Error retrieving list: %v", err)
errorResponse(rw, "internal error", 500)
return
}
items := []*Item{}
for cur.Next() {
item := &Item{}
if err := cur.Scan(&item.ID, &item.Description, &item.User); err != nil {
log.Printf("Error retrieving item: %v", err)
errorResponse(rw, "internal error", 500)
return
}
items = append(items, item)
}
resp := &struct {
List []*Item `json:"list"`
}{List: items}
body, err := json.Marshal(resp)
if err != nil {
log.Printf("Error marshalling items: %v", err)
errorResponse(rw, "internal error", 500)
return
}
rw.WriteHeader(200)
rw.Write(body)
}
func AddHandler(rw http.ResponseWriter, req *http.Request) {
addHeaders(rw)
if req.Method == "OPTIONS" {
return
}
tx, err := DB.Begin()
if err != nil {
log.Printf("Error begining transaction: %v", err)
errorResponse(rw, "internal error", 500)
return
}
item := &Item{}
if err := json.NewDecoder(req.Body).Decode(item); err != nil {
log.Printf("Error decoding request: %v", err)
errorResponse(rw, "internal error", 500)
tx.Rollback()
return
}
item.ID = fmt.Sprintf("%x", rand.Int63())
_, err = tx.Exec(
"INSERT INTO items (id, description) VALUES (?, ?)",
item.ID, item.Description,
)
if err != nil {
log.Printf("Error inserting item: %v", err)
errorResponse(rw, "internal error", 500)
tx.Rollback()
return
}
if err := tx.Commit(); err != nil {
log.Printf("Error committing item: %v", err)
errorResponse(rw, "internal error", 500)
tx.Rollback()
return
}
req.URL.RawQuery = ""
req.URL.Fragment = ""
rw.Header().Add("Location", req.URL.String()+"/"+item.ID)
rw.WriteHeader(201)
json.NewEncoder(rw).Encode(item)
}
func UpdateHandler(rw http.ResponseWriter, req *http.Request) {
addHeaders(rw)
if req.Method == "OPTIONS" {
return
}
tx, err := DB.Begin()
if err != nil {
log.Printf("Error begining transaction: %v", err)
errorResponse(rw, "internal error", 500)
return
}
newitem := &Item{}
if err := json.NewDecoder(req.Body).Decode(newitem); err != nil {
log.Printf("Error decoding request: %v", err)
errorResponse(rw, "invalid json in request", 400)
tx.Rollback()
return
}
vars := mux.Vars(req)
newitem.ID = vars["id"]
if newitem.ID == "" {
log.Printf("Empty ID: %v", vars)
errorResponse(rw, "empty ID", 400)
tx.Rollback()
return
}
{
olditem := &Item{ID: "id"}
row := tx.QueryRow("SELECT * FROM items WHERE id = ? LIMIT 1", newitem.ID)
if err := row.Scan(&olditem.ID, &olditem.Description, &olditem.User); err != nil {
log.Printf("Error querying item: %v", err)
errorResponse(rw, "internal error", 500)
tx.Rollback()
return
}
newitem.Description = olditem.Description
}
_, err = tx.Exec(
"UPDATE items SET description = ?, user = ? WHERE id = ?",
newitem.Description, newitem.User, newitem.ID,
)
if err != nil {
log.Printf("Error updating item: %v", err)
errorResponse(rw, "internal error", 500)
tx.Rollback()
return
}
if err := tx.Commit(); err != nil {
log.Printf("Error committing item: %v", err)
errorResponse(rw, "internal error", 500)
tx.Rollback()
return
}
req.URL.RawQuery = ""
req.URL.Fragment = ""
rw.Header().Add("Location", req.URL.String()+"/"+newitem.ID)
rw.WriteHeader(201)
json.NewEncoder(rw).Encode(newitem)
}
func createTable(table, create string) {
create = fmt.Sprintf(create, table)
tx, err := DB.Begin()
if err != nil {
log.Fatalf("Error beginning transaction: %v", err)
}
row := tx.QueryRow("SELECT COUNT(1) FROM sqlite_master WHERE type = ? AND name = ?", "table", table)
count := 0
if err := row.Scan(&count); err != nil {
log.Fatalf("Error reading results of '%s' table check: %v", table, err)
}
if count > 0 {
tx.Rollback()
return
}
if _, err := tx.Exec(create); err != nil {
log.Fatalf("Error creating table %s: %v", table, err)
}
if err := tx.Commit(); err != nil {
log.Fatalf("Error commiting table creation %s: %v", table, err)
}
}
func main() {
log.SetFlags(log.Ldate | log.Lmicroseconds | log.Lshortfile)
bind := flag.String("bind", "localhost:8000", "host:port to listen on")
dbFile := flag.String("db", "signup.sqlite3", "filename for db")
staticPath := flag.String("path", "www", "path to static www assests")
flag.Parse()
router, err := setup(*staticPath, *dbFile)
if err != nil {
log.Fatalf("Error starting up: %v", err)
}
m := http.NewServeMux()
m.Handle("/", router)
log.Printf("Starting %s on http://%s", path.Base(os.Args[0]), *bind)
log.Fatal(http.ListenAndServe(*bind, m))
}
func initDB() {
createTable("items", "CREATE TABLE %s ( id TEXT PRIMARY KEY, description TEXT NOT NULL DEFAULT '', user TEXT NOT NULL DEFAULT '' )")
}
func setup(staticPath, dbFile string) (*mux.Router, error) {
var err error
if DB, err = sql.Open("sqlite3", dbFile); err != nil {
return nil, fmt.Errorf("Error opening database: %v", err)
}
initDB()
r := mux.NewRouter()
r.HandleFunc("/api/list", GetHandler).Methods("GET", "OPTIONS")
r.HandleFunc("/api/list", AddHandler).Methods("POST", "OPTIONS")
r.HandleFunc("/api/list/{id}", UpdateHandler).Methods("POST", "OPTIONS")
r.PathPrefix("/").Handler(http.FileServer(http.Dir(staticPath)))
return r, nil
}