clipmenud

#!/bin/bash

# A typical file name restriction is 255 bytes (tmpfs/extX/ntfs/...).
# Timestamp + line count will typically require less than 40 of those.
readonly LINE_LENGTH_LIMIT=210

# Use ⁄ ("fraction slash") for replacing slashes in file names.
readonly SLASH_REPLACER='⁄'
readonly CACHE_DIR=/tmp/clipmenu.$USER/
mkdir -p -m0700 "$CACHE_DIR"

declare -A last_data
declare -A last_filename

while sleep "${CLIPMENUD_SLEEP:-0.5}"; do
    for selection in clipboard primary; do
        # TODO Evaluating existence just once, would (currently) result in a 2 % performance gain.
        #      Entirely removing the conditon, would increase performance by 28 %.
        if type -p xsel &>/dev/null; then
            data=$(xsel --"$selection"; printf x)
            # Take ownership of the clipboard, in case the original application
            # is unable to serve the clipboard request (due to being suspended,
            # etc).
            #
            # Primary is excluded from the change of ownership as applications
            # sometimes act up if clipboard focus is taken away from them --
            # for example, urxvt will unhilight text, which is undesirable.
            if [[ $selection != primary ]]; then
                xsel --"$selection" | xsel -i --"$selection"
            fi
        else
            data=$(xclip -o -sel "$selection"; printf x)
            # See above comments about taking ownership of the clipboard for
            # context.
            if [[ $selection != primary ]]; then
                xclip -o -sel "$selection" | xclip -i -sel "$selection"
            fi
        fi

        # We add and remove the x so that trailing newlines are not stripped.
        # Otherwise, they would be stripped by the very nature of how POSIX
        # defines command substitution.
        data=${data%x}

        # If $data is blank, return to top of the loop.
        [[ $data == *[^[:blank:]]* ]] || continue

        # If $data is unchanged, return to top of the loop.
        [[ ${last_data[$selection]} == "$data" ]] && continue

        # If we were in the middle of doing a selection when the previous poll
        # ran, then we may have got a partial clip. This considers selections
        # from left to right as well as selections from right to left.
        possible_partial=${last_data[$selection]}
        if [[ $possible_partial && $data == *"$possible_partial"* ]]; then
            rm -- "${last_filename[$selection]}"
        fi

        lines=$(echo "$data" | wc -l)
        # This ALIGNS the line count at the left of any clipboard entry.
        filename="$CACHE_DIR/$(printf %2d $lines)"

        # We look for the first line matching regex /./ here because we want the
        # first line that can provide reasonable context to the user. That is, if
        # you have 5 leading lines of whitespace, displaying " (6 lines)" is much
        # less useful than displaying "foo (6 lines)", where "foo" is the first
        # line in the entry with actionable context.
        first_line=$(echo "$data" | sed -n '/./{p;q}' | sed "s#\/#$SLASH_REPLACER#g" | cut -c1-"$LINE_LENGTH_LIMIT")
        filename+="  $first_line"

        last_data[$selection]=$data
        last_filename[$selection]=$filename

        printf '%s' "$data" > "$filename"
    done
done