#!/bin/bash

: "${CM_DIR="${XDG_RUNTIME_DIR-"${TMPDIR-/tmp}"}"}"
CM_REAL_DELETE=0
[[ $1 == -d ]] && CM_REAL_DELETE=1

major_version=5

shopt -s nullglob

cache_dir=$CM_DIR/clipmenu.$major_version.$USER
cache_file_prefix=$cache_dir/line_cache
lock_file=$cache_dir/lock
lock_timeout=2

if [[ $1 == --help ]] || [[ $1 == -h ]]; then
    cat << 'EOF'
clipdel deletes clipmenu entries matching a regex. By default, just lists what
it would delete, pass -d to do it for real.

".*" is special, it will just nuke the entire data directory, including the
line caches and all other state.

Arguments:

    -d  Delete for real.

Environment variables:

- $CM_DIR: specify the base directory to store the cache dir in (default: $XDG_RUNTIME_DIR, $TMPDIR, or /tmp)
EOF
    exit 0
fi

line_cache_files=( "$cache_file_prefix"_* )

if (( ${#line_cache_files[@]} == 0 )); then
    printf '%s\n' "No line cache files found, no clips exist" >&2
    exit 0  # Well, this is a kind of success...
fi

# https://github.com/koalaman/shellcheck/issues/1141
# shellcheck disable=SC2124
raw_pattern=${@: -1}
esc_pattern=${raw_pattern/\#/'\#'}

if ! [[ $raw_pattern ]]; then
    printf '%s\n' 'No pattern provided, see --help' >&2
    exit 2
fi

exec {lock_fd}> "$lock_file"

if (( CM_REAL_DELETE )) && [[ "$raw_pattern" == ".*" ]]; then
    flock -x -w "$lock_timeout" "$lock_fd" || exit
    rm -rf -- "$cache_dir"
    exit 0
else
    mapfile -t matches < <(
        cat "${line_cache_files[@]}" | cut -d' ' -f2- | sort -u |
            sed -n "\\#${esc_pattern}#p"
    )

    if (( CM_REAL_DELETE )); then
        flock -x -w "$lock_timeout" "$lock_fd" || exit

        for match in "${matches[@]}"; do
            ck=$(cksum <<< "$match")
            rm -f -- "$cache_dir/$ck"
        done

        for file in "${line_cache_files[@]}"; do
            temp=$(mktemp)
            cut -d' ' -f2- < "$file" | sed "\\#${esc_pattern}#d" > "$temp"
            mv -- "$temp" "$file"
        done

        flock -u "$lock_fd"
    else
        if (( ${#matches[@]} )); then
            printf '%s\n' "${matches[@]}"
        fi
    fi
fi