feat: limit to four events by day - fix #2

R/add_events.R

@@ -10,6 +10,8 @@ add_events <- function(data, year, month, palette) {
   calendar <- get_calendar(year, month)
   data     <- filter_events(data, year, month)
 
+  check_events(data)
+
   if (nrow(data) > 0) {
 
     ## Add color to data ----

R/check_events.R

@@ -0,0 +1,40 @@
+#' Check if the max number of events by day is < 5
+#' 
+#' @note
+#' For internal purpose only
+#' 
+#' @noRd
+
+check_events <- function(data) {
+
+  if (!is.data.frame(data)) {
+    stop("Argument 'data' must be a data.frame", call. = FALSE)
+  }
+
+  if (nrow(data) > 0) {
+
+    if (!("from" %in% colnames(data))) {
+      stop("Column 'from' (start of the event) is missing from 'data'",
+           call. = FALSE)
+    }
+
+    if (!("to" %in% colnames(data))) {
+      stop("Column 'to' (end of the event) is missing from 'data'",
+           call. = FALSE)
+    }
+
+    days <- unlist(lapply(1:nrow(data), function(i) {
+      as.character(seq(as.Date(data[i, "from"]), as.Date(data[i, "to"]), 
+                       by = "days"))
+    }))
+
+    n_events_by_day <- table(days)
+
+    if (max(n_events_by_day) > 4) {
+      stop("Too many events by day. For aesthetic purpose, only 4 four events ",
+           "by day is supported.", call. = FALSE)
+    }
+  }
+
+  invisible(NULL)
+}