First Commit

cmd/api/errors.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func (app *application) logError(r *http.Request, err error) {
+	app.logger.Error(err, "properties", map[string]string{
+		"request_method": r.Method,
+		"request_url":    r.URL.String(),
+	})
+}
+
+func (app *application) errorResponse(w http.ResponseWriter, r *http.Request, status int, message any) {
+	env := envelope{"error": message}
+
+	err := app.writeJSON(w, status, env, nil)
+	if err != nil {
+		app.logError(r, err)
+		w.WriteHeader(500)
+	}
+}
+
+func (app *application) serverErrorResponse(w http.ResponseWriter, r *http.Request, err error) {
+	app.logError(r, err)
+	message := "the server encountered a problem and could not process your request"
+	app.errorResponse(w, r, http.StatusInternalServerError, message)
+}
+
+func (app *application) notFoundResponse(w http.ResponseWriter, r *http.Request) {
+	message := "the requested resource could not be found"
+	app.errorResponse(w, r, http.StatusNotFound, message)
+}
+
+func (app *application) methodNotAllowedResponse(w http.ResponseWriter, r *http.Request) {
+	message := fmt.Sprintf("the %s method is not supported for this resource", r.Method)
+	app.errorResponse(w, r, http.StatusMethodNotAllowed, message)
+}
+
+func (app *application) badRequestResponse(w http.ResponseWriter, r *http.Request, err error) {
+	app.errorResponse(w, r, http.StatusBadRequest, err.Error())
+}
+
+func (app *application) failedValidationResponse(w http.ResponseWriter, r *http.Request, errors map[string]string) {
+	app.errorResponse(w, r, http.StatusUnprocessableEntity, errors)
+}
+
+func (app *application) editConflictResponse(w http.ResponseWriter, r *http.Request) {
+	message := "unable to update the record due to an edit conflict, please try again"
+	app.errorResponse(w, r, http.StatusConflict, message)
+}
+
+func (app *application) rateLimitExceededResponse(w http.ResponseWriter, r *http.Request) {
+	message := "rate limit exceeded"
+	app.errorResponse(w, r, http.StatusTooManyRequests, message)
+}

cmd/api/healthcheck.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"net/http"
+)
+
+func (app *application) healthcheckHandler(w http.ResponseWriter, r *http.Request) {
+	env := envelope{
+		"status": "available",
+		"system_info": map[string]string{
+			"environment": app.config.env,
+			"version":     version,
+		},
+	}
+
+	err := app.writeJSON(w, http.StatusOK, env, nil)
+	if err != nil {
+		app.serverErrorResponse(w, r, err)
+	}
+}

cmd/api/helpers.go

@@ -0,0 +1,123 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"github.com/julienschmidt/httprouter"
+	"greenlight.chipa.me/internal/validator"
+)
+
+func (app *application) readIDParam(r *http.Request) (int64, error) {
+	params := httprouter.ParamsFromContext(r.Context())
+
+	id, err := strconv.ParseInt(params.ByName("id"), 10, 64)
+	if err != nil || id < 1 {
+		return 0, errors.New("invalid id parameter")
+	}
+
+	return id, nil
+}
+
+type envelope map[string]any
+
+func (app *application) writeJSON(w http.ResponseWriter, status int, data envelope, headers http.Header) error {
+	js, err := json.MarshalIndent(data, "", "\t")
+	if err != nil {
+		return err
+	}
+
+	js = append(js, '\n')
+	for key, value := range headers {
+		w.Header()[key] = value
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	w.Write(js)
+	return nil
+}
+
+func (app *application) readJSON(w http.ResponseWriter, r *http.Request, dst any) error {
+	maxBytes := 1_048_576
+
+	r.Body = http.MaxBytesReader(w, r.Body, int64(maxBytes))
+	dec := json.NewDecoder(r.Body)
+	dec.DisallowUnknownFields()
+
+	err := dec.Decode(dst)
+	if err != nil {
+		var syntaxError *json.SyntaxError
+		var unmarshalTypeError *json.UnmarshalTypeError
+		var invalidUnmarshalError *json.InvalidUnmarshalError
+		var maxBytesError *http.MaxBytesError
+
+		switch {
+		case errors.As(err, &syntaxError):
+			return fmt.Errorf("body contains badly-formed JSON (at character %d)", syntaxError.Offset)
+		case errors.Is(err, io.ErrUnexpectedEOF):
+			return errors.New("body contains badly-formed JSON")
+		case errors.As(err, &unmarshalTypeError):
+			if unmarshalTypeError.Field != "" {
+				return fmt.Errorf("body contains incorrect JSON type for field %q", unmarshalTypeError.Field)
+			}
+			return fmt.Errorf("body contains incorrect JSON type (at character %d)", unmarshalTypeError.Offset)
+		case errors.Is(err, io.EOF):
+			return errors.New("body must not be empty")
+		case strings.HasPrefix(err.Error(), "json: unknown field "):
+			fieldName := strings.TrimPrefix(err.Error(), "json: unknown field ")
+			return fmt.Errorf("body contains unknown key %s", fieldName)
+		case errors.As(err, &maxBytesError):
+			return fmt.Errorf("body must not be larger than %d bytes", maxBytesError.Limit)
+		case errors.As(err, &invalidUnmarshalError):
+			panic(err)
+		default:
+			return err
+		}
+	}
+
+	err = dec.Decode(&struct{}{})
+	if err != io.EOF {
+		return errors.New("body must only contain a single JSON value")
+	}
+	return nil
+}
+
+func (app *application) readString(qs url.Values, key string, defaultValue string) string {
+	s := qs.Get(key)
+	if s == "" {
+		return defaultValue
+	}
+
+	return s
+}
+
+func (app *application) readCSV(qs url.Values, key string, defaultValue []string) []string {
+	csv := qs.Get(key)
+	if csv == "" {
+		return defaultValue
+	}
+
+	return strings.Split(csv, ",")
+}
+
+func (app *application) readInt(qs url.Values, key string, defaultValue int, v *validator.Validator) int {
+	s := qs.Get(key)
+	if s == "" {
+		return defaultValue
+	}
+
+	i, err := strconv.Atoi(s)
+	if err != nil {
+		v.AddError(key, "must be an integer value")
+		return defaultValue
+	}
+
+	return i
+}

cmd/api/main.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"flag"
+	"os"
+	"time"
+
+	"github.com/charmbracelet/log"
+
+	_ "github.com/lib/pq"
+	"greenlight.chipa.me/internal/data"
+)
+
+const version = "1.0.0"
+
+type config struct {
+	port int
+	env  string
+	db   struct {
+		dsn          string
+		maxOpenConns int
+		maxIdleConns int
+		maxIdleTime  string
+	}
+	limiter struct {
+		rps     float64
+		burst   int
+		enabled bool
+	}
+}
+
+type application struct {
+	config config
+	logger *log.Logger
+	models data.Models
+}
+
+func main() {
+	var cfg config
+	flag.IntVar(&cfg.port, "port", 4000, "API server port")
+	flag.StringVar(&cfg.env, "env", "development", "Environment (development|staging|production)")
+	flag.StringVar(&cfg.db.dsn, "db-dsn", os.Getenv("GREENLIGHT_DB_DSN"), "PostgreSQL DSN")
+
+	flag.IntVar(&cfg.db.maxOpenConns, "db-max-open-conns", 25, "PostgreSQL max open connections")
+	flag.IntVar(&cfg.db.maxIdleConns, "db-max-idle-conns", 25, "PostgreSQL max idle connections")
+	flag.StringVar(&cfg.db.maxIdleTime, "db-max-idle-time", "15m", "PostgreSQL max connection idle time")
+
+	flag.Float64Var(&cfg.limiter.rps, "limiter-rps", 2, "Rate limiter maximum requests per second")
+	flag.IntVar(&cfg.limiter.burst, "limiter-burst", 4, "Rate limiter maximum burst")
+	flag.BoolVar(&cfg.limiter.enabled, "limiter-enabled", true, "Enable rate limiter")
+	flag.Parse()
+
+	logger := log.NewWithOptions(os.Stderr, log.Options{
+		Level:           log.DebugLevel,
+		Formatter:       log.JSONFormatter,
+		ReportCaller:    true,
+		ReportTimestamp: true,
+	})
+
+	db, err := openDB(cfg)
+	if err != nil {
+		logger.Fatal(err)
+	}
+	defer db.Close()
+	logger.Info("database connection pool established")
+
+	app := &application{
+		config: cfg,
+		logger: logger,
+		models: data.NewModels(db),
+	}
+
+	err = app.serve()
+	if err != nil {
+		logger.Fatal(err)
+	}
+}
+func openDB(cfg config) (*sql.DB, error) {
+	db, err := sql.Open("postgres", cfg.db.dsn)
+	if err != nil {
+		return nil, err
+	}
+
+	db.SetMaxOpenConns(cfg.db.maxOpenConns)
+	db.SetMaxIdleConns(cfg.db.maxIdleConns)
+	duration, err := time.ParseDuration(cfg.db.maxIdleTime)
+	if err != nil {
+		return nil, err
+	}
+	db.SetConnMaxIdleTime(duration)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	err = db.PingContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	return db, nil
+}

cmd/api/middleware.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+	"sync"
+	"time"
+
+	"golang.org/x/time/rate"
+)
+
+func (app *application) recoverPanic(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
+		defer func() {
+			if err := recover(); err != nil {
+				w.Header().Set("Connection", "close")
+				app.serverErrorResponse(w, r, fmt.Errorf("%s", err))
+			}
+		}()
+
+		next.ServeHTTP(w, r)
+	})
+}
+
+func (app *application) rateLimit(next http.Handler) http.Handler {
+	type client struct {
+		limiter  *rate.Limiter
+		lastSeen time.Time
+	}
+
+	var (
+		mu      sync.Mutex
+		clients = make(map[string]*client)
+	)
+
+	go func() {
+		for {
+			time.Sleep(time.Minute)
+			mu.Lock()
+			for ip, client := range clients {
+				if time.Since(client.lastSeen) > 3*time.Minute {
+					delete(clients, ip)
+				}
+			}
+			mu.Unlock()
+		}
+	}()
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if app.config.limiter.enabled {
+			ip, _, err := net.SplitHostPort(r.RemoteAddr)
+			if err != nil {
+				app.serverErrorResponse(w, r, err)
+				return
+			}
+
+			mu.Lock()
+			if _, found := clients[ip]; !found {
+				clients[ip] = &client{
+					limiter: rate.NewLimiter(rate.Limit(app.config.limiter.rps), app.config.limiter.burst),
+				}
+			}
+
+			clients[ip].lastSeen = time.Now()
+			if !clients[ip].limiter.Allow() {
+				mu.Unlock()
+				app.rateLimitExceededResponse(w, r)
+				return
+			}
+			mu.Unlock()
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}