tsk-13: Retrieve scheduled message endpoint (#36)

Closes #13

Reviewed-on: phoenix/textsender-api#36
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

internal/handler/scheduled_message.go

@@ -24,6 +24,11 @@ type AddScheduledMessageResponse struct {
 	Data    []scheduling.ScheduledMessage `json:"data"`
 }
 
+type GetScheduledMessageResponse struct {
+	Message string                        `json:"message"`
+	Data    []scheduling.ScheduledMessage `json:"data"`
+}
+
 type ScheduledMessageHandler struct {
 	ScheduledMessageStore store.ScheduledMessageStore
 }
@@ -83,6 +88,70 @@ func (c *ScheduledMessageHandler) AddScheduledMessage(w http.ResponseWriter, r *
 	RespondWithJSON(w, statusCode, &resp)
 }
 
+func (c *ScheduledMessageHandler) GetScheduledMessage(w http.ResponseWriter, r *http.Request) {
+	var id, userId uuid.UUID
+
+	if idParam, err := ParseQueryParams(r, "id"); err == nil {
+		var err error
+		id, err = uuid.Parse(*idParam)
+		if err != nil {
+			http.Error(w, "Error parsing Id", http.StatusBadRequest)
+			return
+		}
+	}
+	if userIdParam, err := ParseQueryParams(r, "user_id"); err == nil {
+		userId, err = uuid.Parse(*userIdParam)
+		if err != nil {
+			http.Error(w, "Error parsing Id", http.StatusBadRequest)
+			return
+		}
+	}
+
+	var resp GetScheduledMessageResponse
+	var statusCode int
+	ctx := r.Context()
+
+	if userId == uuid.Nil && id == uuid.Nil {
+		http.Error(w, "Invalid query parameters", http.StatusBadRequest)
+		return
+	} else if userId != uuid.Nil && id != uuid.Nil {
+		if schMsgs, err := c.ScheduledMessageStore.GetWithUserId(ctx, userId); err != nil {
+			statusCode = http.StatusInternalServerError
+			resp.Message = err.Error()
+		} else {
+			for _, schMsg := range schMsgs {
+				if schMsg.Id == id {
+					resp.Data = append(resp.Data, *schMsg)
+				}
+			}
+			statusCode = http.StatusOK
+			resp.Message = "Successful"
+		}
+	} else if id != uuid.Nil {
+		if schMsg, err := c.ScheduledMessageStore.Get(ctx, id); err != nil {
+			statusCode = http.StatusInternalServerError
+			resp.Message = err.Error()
+		} else {
+			statusCode = http.StatusOK
+			resp.Message = "Successful"
+			resp.Data = append(resp.Data, *schMsg)
+		}
+	} else {
+		if schMsgs, err := c.ScheduledMessageStore.GetWithUserId(ctx, userId); err != nil {
+			statusCode = http.StatusInternalServerError
+			resp.Message = err.Error()
+		} else {
+			statusCode = http.StatusOK
+			resp.Message = "Successful"
+			for _, schMsg := range schMsgs {
+				resp.Data = append(resp.Data, *schMsg)
+			}
+		}
+	}
+
+	RespondWithJSON(w, statusCode, &resp)
+}
+
 func isScheduledTimeValid(schMsg *scheduling.ScheduledMessage) (bool, error) {
 	now := time.Now()
 	timeCutOff := now.Add(-5 * time.Minute)