feat: Apply date range filtering to DWD index file selection and parsed dataframes for improved data loading.

fun/parse_dwd.R

@@ -108,13 +108,15 @@ read_dwd_data <- function(zip_path, start_date = NULL, end_date = NULL) {
             # Filter valid dates
             df <- df[!is.na(df$datetime), ]
 
-            # Window Filter - REMOVED to allow caller to inspect full range
-            # if (!is.null(start_date)) {
-            #     df <- df[df$datetime >= (as.POSIXct(start_date) - days(1)), ]
-            # }
-            # if (!is.null(end_date)) {
-            #     df <- df[df$datetime <= (as.POSIXct(end_date) + days(1)), ]
-            # }
+            # Window Filter - Discard rows outside requested window immediately to save memory/processing
+            if (!is.null(start_date)) {
+                s_limit <- as.POSIXct(start_date)
+                df <- df[df$datetime >= s_limit, ]
+            }
+            if (!is.null(end_date)) {
+                e_limit <- as.POSIXct(end_date) + days(1) # Include the end date fully
+                df <- df[df$datetime <= e_limit, ]
+            }
 
             # Column Mapping
             weather_cols <- c(

server.R

@@ -548,11 +548,40 @@ server <- function(input, output, session) {
         # Freeze UI during download and parsing - include station name
         session$sendCustomMessage("freezeUI", list(text = msg, station = station_name))
 
-        # Generate Filtered Index
-        targets <- current_index() %>% filter(id == station_id)
+        # Generate Filtered Index - Optimize based on Date Range
+        req_start_date <- as.Date(window_debounced()$start)
+        req_end_date <- as.Date(window_debounced()$end)
+
+        # Helper to convert YYYYMMDD string to Date
+        parse_dwd_date <- function(x) {
+            as.Date(x, format = "%Y%m%d")
+        }
+
+        targets <- current_index() %>%
+            filter(id == station_id) %>%
+            filter(
+                # Logic: Keep file if (FileStart <= ReqEnd) AND (FileEnd >= ReqStart)
+                # Handle cases where start/end might be NA or "recent" type implies checking
+                type == "recent" | # Always check recent files as they might have fresh data
+                    type == "solar" | # Solar usually has one file or simple structure, keep safe
+                    (
+                        !is.na(start_date) & !is.na(end_date) &
+                            parse_dwd_date(start_date) <= req_end_date &
+                            parse_dwd_date(end_date) >= req_start_date
+                    )
+            )
 
         if (nrow(targets) == 0) {
-            reset_fetch("No data found in index for this station.")
+            # Fallback/Debug: check if we filtered out everything
+            raw_targets <- current_index() %>% filter(id == station_id)
+            msg <- "No data found in index for this station."
+
+            if (nrow(raw_targets) > 0) {
+                # Data exists but was filtered out by date range
+                msg <- "No data found for the selected date range."
+            }
+
+            reset_fetch(msg)
             return()
         }