give the user an affordance if run on the wrong file type

Author: idrisr

packages/srtcpy.nix

@@ -3,3 +3,4 @@ writeShellApplication {
   name = "srtcpy";
   text = builtins.readFile ./srtcpy.sh;
 }
+# see https://hackage.haskell.org/package/subtitleParser

packages/srtcpy.sh

@@ -5,25 +5,19 @@ if [ -z "$1" ]; then
 fi
 
 filename="$1"
+srt_filename="${filename%.*}.srt"  # Remove extension (if any) and append .srt
 
-# Check if the file has a .srt extension
-if [[ "$filename" != *.srt ]]; then
-    echo "Error: File '$filename' is not a .srt file."
-    exit 1
-fi
-
-# Check if the file exists
-if [ ! -f "$filename" ]; then
-    echo "Error: File '$filename' not found."
+# Check if the .srt file exists
+if [ ! -f "$srt_filename" ]; then
+    echo "Error: File '$srt_filename' not found."
     exit 1
 fi
 
 instructions="Instructions: Summarize the following article."
 start_tag="[START ARTICLE]"
 end_tag="[END ARTICLE]"
 
-
-output=$(tr -d '\r' < "$filename" | \
+output=$(tr -d '\r' < "$srt_filename" | \
         sed -e '/^[[:space:]]*$/d' -e '/^[0-9]/d' | \
     uniq)