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-rw-r--r--srv/src/http/apiutil/apiutil.go139
1 files changed, 139 insertions, 0 deletions
diff --git a/srv/src/http/apiutil/apiutil.go b/srv/src/http/apiutil/apiutil.go
new file mode 100644
index 0000000..d427b65
--- /dev/null
+++ b/srv/src/http/apiutil/apiutil.go
@@ -0,0 +1,139 @@
+// Package apiutil contains utilities which are useful for implementing api
+// endpoints.
+package apiutil
+
+import (
+ "context"
+ "crypto/rand"
+ "encoding/hex"
+ "encoding/json"
+ "errors"
+ "fmt"
+ "net/http"
+ "strconv"
+ "strings"
+
+ "github.com/mediocregopher/mediocre-go-lib/v2/mlog"
+)
+
+type loggerCtxKey int
+
+// SetRequestLogger sets the given Logger onto the given Request's Context,
+// returning a copy.
+func SetRequestLogger(r *http.Request, logger *mlog.Logger) *http.Request {
+ ctx := r.Context()
+ ctx = context.WithValue(ctx, loggerCtxKey(0), logger)
+ return r.WithContext(ctx)
+}
+
+// GetRequestLogger returns the Logger which was set by SetRequestLogger onto
+// this Request, or nil.
+func GetRequestLogger(r *http.Request) *mlog.Logger {
+ ctx := r.Context()
+ logger, _ := ctx.Value(loggerCtxKey(0)).(*mlog.Logger)
+ if logger == nil {
+ logger = mlog.Null
+ }
+ return logger
+}
+
+// JSONResult writes the JSON encoding of the given value as the response body.
+func JSONResult(rw http.ResponseWriter, r *http.Request, v interface{}) {
+ b, err := json.Marshal(v)
+ if err != nil {
+ InternalServerError(rw, r, err)
+ return
+ }
+ b = append(b, '\n')
+
+ rw.Header().Set("Content-Type", "application/json")
+ rw.Write(b)
+}
+
+// BadRequest writes a 400 status and a JSON encoded error struct containing the
+// given error as the response body.
+func BadRequest(rw http.ResponseWriter, r *http.Request, err error) {
+ GetRequestLogger(r).Warn(r.Context(), "bad request", err)
+
+ rw.WriteHeader(400)
+ JSONResult(rw, r, struct {
+ Error string `json:"error"`
+ }{
+ Error: err.Error(),
+ })
+}
+
+// InternalServerError writes a 500 status and a JSON encoded error struct
+// containing a generic error as the response body (though it will log the given
+// one).
+func InternalServerError(rw http.ResponseWriter, r *http.Request, err error) {
+ GetRequestLogger(r).Error(r.Context(), "internal server error", err)
+
+ rw.WriteHeader(500)
+ JSONResult(rw, r, struct {
+ Error string `json:"error"`
+ }{
+ Error: "internal server error",
+ })
+}
+
+// StrToInt parses the given string as an integer, or returns the given default
+// integer if the string is empty.
+func StrToInt(str string, defaultVal int) (int, error) {
+ if str == "" {
+ return defaultVal, nil
+ }
+ return strconv.Atoi(str)
+}
+
+// GetCookie returns the namd cookie's value, or the given default value if the
+// cookie is not set.
+//
+// This will only return an error if there was an unexpected error parsing the
+// Request's cookies.
+func GetCookie(r *http.Request, cookieName, defaultVal string) (string, error) {
+ c, err := r.Cookie(cookieName)
+ if errors.Is(err, http.ErrNoCookie) {
+ return defaultVal, nil
+ } else if err != nil {
+ return "", fmt.Errorf("reading cookie %q: %w", cookieName, err)
+ }
+
+ return c.Value, nil
+}
+
+// RandStr returns a human-readable random string with the given number of bytes
+// of randomness.
+func RandStr(numBytes int) string {
+ b := make([]byte, numBytes)
+ if _, err := rand.Read(b); err != nil {
+ panic(err)
+ }
+ return hex.EncodeToString(b)
+}
+
+// MethodMux will take the request method (GET, POST, etc...) and handle the
+// request using the corresponding Handler in the given map.
+//
+// If no Handler is defined for a method then a 405 Method Not Allowed error is
+// returned.
+func MethodMux(handlers map[string]http.Handler) http.Handler {
+
+ return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+
+ method := strings.ToUpper(r.FormValue("method"))
+
+ if method == "" {
+ method = strings.ToUpper(r.Method)
+ }
+
+ handler, ok := handlers[method]
+
+ if !ok {
+ http.Error(rw, "Method not allowed", http.StatusMethodNotAllowed)
+ return
+ }
+
+ handler.ServeHTTP(rw, r)
+ })
+}