fix: fix the preview script

helper/preview.sh

@@ -9,13 +9,30 @@
 #   reset_seq: reset highlight sequence for eaiser print
 #   input_option: the array containing informaiton from cmd argument
 #   preview_file: the file path to be previewed
-#   preview_center: the center line of the preview, if not set, display entire file
+#   preview_center: the center/highlight line of the preview, if not set, display entire file
+#   preview_lines: total lines to be previed, used to determine the first line and last line to be printed
+#   preview_first: the first line number of the file to be printed
+#   preview_last: the last line number of the file to be printed
+#   file_mime: mime of the file, used to display information for binary file
 # Arguments
 #   $1: The filename and line info to be previewed
 #     Format: filepath[:lineno][:ignored]
 # Example
 #   preview "$HOME/.bashrc:15"
 
+#######################################
+# display the preview of the file
+# construct argument for the action, execute and exit
+# Arguments:
+#   $1: the file path to be previewed
+#   $2: the first line number to be previewd, optional
+#   $3: the center/highlight line in the preview, optional
+#   $4: the last line number to be previewed, optional
+# Note:
+#   if the line number information such as $2 $3 $4 is not given, the entire
+#   file will be printed.
+#   Otherwise only the $2-$4 parts of the file will be printed and $3 will be highlighted
+#######################################
 function display_preview() {
   local fallback_cmd preview_cmd preview_file preview_first preview_last preview_center
   preview_file="$1"
@@ -26,16 +43,16 @@ function display_preview() {
   preview_cmd=${DOTBARE_PREVIEW:-${fallback_cmd}}
   preview_cmd=${preview_cmd//{\}/$(printf %q "${preview_file}")}
 
-  if [[ "$#" -lt 2 ]]; then
+  if [[ -z "${preview_first}" ]] || [[ -z "${preview_center}" ]] || [[ -z "${preview_last}" ]]; then
     if [[ -z "${DOTBARE_PREVIEW}" ]] && command -v bat > /dev/null; then
-      bat --style="${BAT_STYLE:-numbers}" --color=always --pager=never "${preview_file}"
+      bat --style="${BAT_STYLE:-plain}" --color=always --pager=never "${preview_file}"
       exit $?
     fi
     eval "${preview_cmd}" 2> /dev/null
     exit 0
   else
     if [ -z "${DOTBARE_PREVIEW}" ] && command -v bat > /dev/null; then
-      bat --style="${BAT_STYLE:-numbers}" --color=always --pager=never \
+      bat --style="${BAT_STYLE:-plain}" --color=always --pager=never \
           --line-range="${preview_first}":"${preview_last}" --highlight-line="${preview_center}" "${preview_file}"
       exit $?
     fi
@@ -69,28 +86,33 @@ if [ ! -r "${preview_file}" ]; then
   exit 1
 fi
 
-file_length="${#preview_file}"
-
+# if binary, display binary info and exit
 file_mime=$(file --dereference --mime "${preview_file}")
-if [[ "${file_mime:file_length}" =~ binary ]]; then
-  echo "${file_mime}"
-  exit 0
-fi
-
-[[ -n "${preview_center}" && ! "${preview_center}" =~ ^[0-9] ]] && display_preview "${preview_file}"
+[[ "${file_mime}" =~ binary ]] \
+  && echo "${file_mime}" \
+  && exit 0
 
+# if no line number was given, just preview the entire file
 [[ -z "${preview_center}" ]] && display_preview "${preview_file}"
 
+# if invalid line number was given, just preview the entire file
+[[ -n "${preview_center}" && ! "${preview_center}" =~ ^[0-9] ]] && display_preview "${preview_file}"
+
+# get the size of the termianl window and determine the first line and last line
 preview_center=${preview_center/[^0-9]*/}
 
-if [ -r /dev/tty ]; then
-  preview_lines=$(stty size < /dev/tty | awk '{print $1}')
+if [ -n "${FZF_PREVIEW_LINES}" ]; then
+  preview_lines="${FZF_PREVIEW_LINES}"
 else
-  preview_lines=40
+  if [ -r /dev/tty ]; then
+    preview_lines=$(stty size < /dev/tty | awk '{print $1}')
+  else
+    preview_lines=40
+  fi
 fi
 
-preview_first=$(($preview_center-$preview_lines/3))
-preview_first=$(($preview_first < 1 ? 1 : $preview_first))
-preview_last=$((${preview_first}+${preview_lines}-1))
+preview_first=$((preview_center-preview_lines/3))
+preview_first=$((preview_first < 1 ? 1 : preview_first))
+preview_last=$((preview_first+preview_lines-1))
 
 display_preview "${preview_file}" "${preview_first}" "${preview_center}" "${preview_last}"