Improve robustness of reference year range handling

Added input validation to ensure all year variables are integers and within a valid order.

Normalized start/end pairs so reversed inputs (e.g. y1 > y2, ref_start_yr > ref_final_yr) are automatically swapped.

Recorded the original custom reference range (ref_y1, ref_y2) and clamped it to the available reference window for safe fallback.

Refined the adjustment logic so:

If availability fully covers the analysis period, use [y1, y2].

Otherwise, prefer the clamped custom range and trim only if it extends beyond the analysis window.

If custom and analysis don’t overlap, fall back to the overlap of availability ∩ analysis.

If no overlap exists, fall back to the clamped custom, and finally the full available window.

Ensured final ref_y1 ≤ ref_y2 and applied zero-padding formatting once at the end.

Author: zhangshixuan1987

zppy/templates/pcmdi_diags.bash

@@ -46,23 +46,44 @@ Y2="$(printf "%04d" ${y2})"
 ref_Y1="$(printf "%04d" ${ref_y1})"
 ref_Y2="$(printf "%04d" ${ref_y2})"
 
-# Refine reference range
-if [[ ${ref_y1} -lt ${ref_start_yr} ]]; then
-    ref_y1=${ref_start_yr}
-    ref_Y1="$(printf "%04d" ${ref_y1})"
-fi
-
 num_years=$((y2 - y1 + 1))
 ref_end_yr=$((ref_y1 + num_years - 1))
 
-if [[ ${ref_y2} -gt ${ref_end_yr} ]]; then
-    ref_y2=${ref_end_yr}
-    ref_Y2="$(printf "%04d" ${ref_y2})"
+# Keep originals for fallback
+orig_ref_y1=${ref_y1}
+orig_ref_y2=${ref_y2}
+if [[ ${orig_ref_y1} -lt ${ref_start_yr} ]]; then
+   orig_ref_y1=${ref_start_yr}
 fi
-
-if [[ ${ref_y2} -gt ${ref_final_yr} ]]; then
-    ref_y2=${ref_final_yr}
-    ref_Y2="$(printf "%04d" ${ref_y2})"
+if [[ ${orig_ref_y2} -gt ${ref_final_yr} ]]; then
+   orig_ref_y2=${ref_final_yr}
+fi
+# Refine reference range
+if [[ ${ref_start_yr} -le ${y1} && ${ref_final_yr} -ge ${y2} ]]; then
+   # Availability fully covers analysis: use [y1, y2]
+   ref_y1=${y1}
+   ref_y2=${y2}
+else
+   # Case 2: Prefer the user's clamped custom window; only tweak if needed
+   # 2a) If clamped custom overlaps the analysis window, use the intersection
+   if [[ ${orig_ref_y1} -le ${y2} && ${orig_ref_y2} -ge ${y1} ]]; then
+      # minimal trimming to fit inside [y1, y2]
+      ref_y1=$(( orig_ref_y1 > y1 ? orig_ref_y1 : y1 ))
+      ref_y2=$(( orig_ref_y2 < y2 ? orig_ref_y2 : y2 ))
+   else
+      # 2b) No overlap between custom and analysis:
+      #     try availability i∩ analysis (minimal change wrt both)
+      ovl_start=$(( ref_start_yr > y1 ? ref_start_yr : y1 ))
+      ovl_end=$(( ref_final_yr < y2 ? ref_final_yr : y2 ))
+      if [[ ${ovl_start} -le ${ovl_end} ]]; then
+         ref_y1=${ovl_start}
+         ref_y2=${ovl_end}
+      else
+         # 2c) Truly no overlap possible; fall back to clamped custom window
+         ref_y1=${orig_ref_y1}
+         ref_y2=${orig_ref_y2}
+      fi
+   fi
 fi
 
 {% endif %}