clean up preview script

common/.config/lf/preview

@@ -1,14 +1,31 @@
 #!/bin/sh
+# shellcheck disable=SC2016
+
+# Preview functions for each filetype must print their results to stdout.
+# The preview functions are called by the "run" wrapper function, which handles caching.
+# This wrapper function can take "-s" as an argument to indicate that the
+# preview should be regenerated if the terminal is resized.
 
 f="$(realpath "$1")" w=$2 h=$3 _x=$4 _y=$5
+rs="$(printf "\037")"
 
-RS="$(printf "\037")"
-CACHE="${XDG_CACHE_HOME}/lf/$(stat --printf "%n %i %F %s %W %Y" -- "$(readlink -f "$1")" | sha256sum | awk '{print $1}')"
-SIZED_CACHE="${XDG_CACHE_HOME}/lf/$(stat --printf "%n %i %F %s %W %Y ${w} ${h}" -- "$(readlink -f "$1")" | sha256sum | awk '{print $1}')"
-BAT="bat --style=plain --color=always --italic-text=always --pager=never --tabs=4 --theme=base16 --line-range=:$h --terminal-width=$((w - 2))"
-CHAFA="chafa -f sixel -s ${w}x${h} --polite on --animate false"
-
-# NOTE: preview functions
+CACHE_DIR="${XDG_CACHE_HOME:-"${HOME}/.cache"}/lf"
+BAT="bat \
+    --style=plain \
+    --color=always \
+    --italic-text=always \
+    --pager=never \
+    --tabs=4 \
+    --theme=base16 \
+    --line-range=:$h \
+    --terminal-width=$((w - 2))
+"
+CHAFA="chafa \
+    -f sixel \
+    -s ${w}x${h} \
+    --polite on \
+    --animate false
+"
 
 archive1() {
     7z l "$f" | sed 1,11d
@@ -19,7 +36,9 @@ archive2() {
 }
 
 csv() {
-    mlr --icsv --omd cat "$f" | CLICOLOR_FORCE=1 COLORTERM=truecolor glow -w "$w" -s tokyo-night
+    mlr --icsv --omd cat "$f" |
+        CLICOLOR_FORCE=1 COLORTERM=truecolor \
+            glow -w "$w" -s tokyo-night
 }
 
 docx() {
@@ -51,7 +70,8 @@ lua() {
 }
 
 markdown() {
-    CLICOLOR_FORCE=1 COLORTERM=truecolor glow -w "$w" -s tokyo-night "$f"
+    CLICOLOR_FORCE=1 COLORTERM=truecolor \
+        glow -w "$w" -s tokyo-night "$f"
 }
 
 word() {
@@ -59,7 +79,11 @@ word() {
 }
 
 ods() {
-    ssconvert --export-type=Gnumeric_stf:stf_assistant -O separator="$RS" "$f" "fd://1" | column -t -s "$RS"
+    ssconvert \
+        --export-type=Gnumeric_stf:stf_assistant \
+        -O separator="$rs" \
+        "$f" "fd://1" |
+        column -t -s "$rs"
 }
 
 odt() {
@@ -77,9 +101,9 @@ sqlite() {
         while read -r table; do
             [ "$table" != "name" ] &&
                 printf "SELECT * FROM %s;" "$table" |
-                sqlite3 -header -separator "$RS" "$f"
+                sqlite3 -header -separator "$rs" "$f"
         done |
-        column -t -s "$RS"
+        column -t -s "$rs"
 }
 
 svg() {
@@ -108,14 +132,18 @@ yaml() {
     $BAT --language=yaml "$f"
 }
 
-# NOTE: other functions
-
 run() {
     if [ "$1" = "-s" ]; then
-        cache="$SIZED_CACHE"
+        cache="${CACHE_DIR}/$(
+            stat --printf "%n %i %F %s %W %Y ${w} ${h}" -- "$(readlink -f "$f")" |
+                sha256sum | awk '{print $1}'
+        )"
         shift
     else
-        cache="$CACHE"
+        cache="${CACHE_DIR}/$(
+            stat --printf "%n %i %F %s %W %Y" -- "$(readlink -f "$f")" |
+                sha256sum | awk '{print $1}'
+        )"
     fi
 
     if [ -r "$cache" ]; then
@@ -127,7 +155,6 @@ run() {
 
 preview() {
     mimetype=$1
-
     case "$mimetype" in
         */vnd.openxmlformats-officedocument.spreadsheetml.sheet | */vnd.oasis.opendocument.spreadsheet) run ods ;;
         */vnd.sqlite3) run sqlite ;;
@@ -154,11 +181,21 @@ preview() {
     esac
 }
 
+# We don't want to reprocess files in the cache, as this will generate a bunch of duplicate cache entries
+[ "$(readlink -f "$f" | xargs dirname)" = "${CACHE_DIR}" ] && {
+    cat "$f"
+    exit
+}
+
+# First mimetype detection is made with 'gio info'
 mimetype_gio="$(gio info "$f" 2>/dev/null | grep standard::content-type | cut -d' ' -f4)"
 preview "$mimetype_gio" && exit
+
+# If gio detection fails, we try again with 'file --mime-type'
 mimetype_file="$(file --brief --dereference --mime-type "$f")"
 preview "$mimetype_file" && exit
 
-[ -n "$mimetype_file" ] && printf "%b" "\$(file --mime-type)\t\t\t : ${mimetype_file}\n"
-[ -n "$mimetype_gio" ] && printf "%b" "\$(gio info)\t\t\t\t : ${mimetype_gio}\n"
+# If all detection fails, simply print the results of file and gio
+[ -n "$mimetype_gio" ] && printf '$(gio info)\t\t\t\t : %s\n' "${mimetype_gio}"
+[ -n "$mimetype_file" ] && printf '$(file --mime-type)\t\t\t : %s\n' "${mimetype_file}"
 mediainfo "$1" | head -n -2 | grep -v -e "Complete name" -e "General"