#!/bin/sh
# Font preview with ueberzug and fzf
# https://github.com/OliverLew/fontpreview-ueberzug
# Dependencies: imagemagick, ueberzug, fzf, fontconfig
# This is inspired by https://github.com/sdushantha/fontpreview

# Checking for environment variables if available.
# These are compatible with original fontpreview.
SIZE=${FONTPREVIEW_SIZE:-800x800}
FONT_SIZE=${FONTPREVIEW_FONT_SIZE:-50}
BG_COLOR=${FONTPREVIEW_BG_COLOR:-#080808}
FG_COLOR=${FONTPREVIEW_FG_COLOR:-#b3b1ad}
PREVIEW_TEXT=${FONTPREVIEW_PREVIEW_TEXT:-"Jackdaws Love\nMy Big Sphinx\nOf Quartz\n\n1234567890\n¡!@#$\%|^&*\n',.;:_-=+\"\n(){}[]<>¿?ñÑ"}

# Ueberzug related variables
FIFO="/tmp/fontpreview-ueberzug-fifo"
IMAGE="/tmp/fontpreview-ueberzug-img.png"
ID="fontpreview-ueberzug"
WIDTH=$(tput cols)
HEIGHT=$(tput lines)

usage() {
    echo "Usage: fontpreview [-h] [-s FONT_SIZE] [-b BG] [-f FG] [-t TEXT]"
}

start_ueberzug() {
    mkfifo "$FIFO" || exit 1
    touch "$IMAGE" || exit 1
    ueberzug layer --parser simple --silent <"$FIFO" &
    # https://github.com/seebye/ueberzug/issues/54#issuecomment-502869935
    exec 3>"$FIFO"
}

stop_ueberzug() {
    exec 3>&-
    rm "$FIFO" "$IMAGE" >/dev/null 2>&1
}

preview() {
    # In fzf the cols and lines are those of the preview pane
    [ -f "$1" ] || fontfile=$(fc-match -f "%{file}" "$1")
    convert -size "$SIZE" xc:"$BG_COLOR" -fill "$FG_COLOR" \
        -pointsize "$FONT_SIZE" -font "$fontfile" -gravity center \
        -annotate +0+0 "$PREVIEW_TEXT" "$IMAGE" &&
        {
            printf "action\tadd\tidentifier\t%s\t" "$ID"
            printf "x\t%d\ty\t%d\tpath\t%s\t" 2 1 "$IMAGE"
            printf "width\t%d\theight\t%d\n" "$WIDTH" "$HEIGHT"
        } >"$FIFO" ||
        printf "action\tremove\tidentifier\t%s\n" "$ID" >"$FIFO"
}

while getopts "hs:b:f:t:" arg; do
    case "$arg" in
    s) FONT_SIZE=$OPTARG ;;
    b) BG_COLOR=$OPTARG ;;
    f) FG_COLOR=$OPTARG ;;
    t) PREVIEW_TEXT=$OPTARG ;;
    *)
        usage
        exit
        ;;
    esac
done
shift $((OPTIND - 1))

if [ "$#" = 0 ]; then
    trap stop_ueberzug EXIT QUIT INT TERM
    # Check if dependencies are installed
    for dependency in ueberzug convert fzf fc-list; do
        command -v "$dependency" >/dev/null 2>&1 ||
            {
                echo "Please install ${dependency}." >&2
                exit 1
            }
    done
    # Prepare
    start_ueberzug
    # Export cli args as environment variables for preview command
    export FONTPREVIEW_FONT_SIZE="$FONT_SIZE"
    export FONTPREVIEW_BG_COLOR="$BG_COLOR"
    export FONTPREVIEW_FG_COLOR="$FG_COLOR"
    export FONTPREVIEW_PREVIEW_TEXT="$PREVIEW_TEXT"
    # The preview command runs this script again with an argument
    fc-list -f "%{family}:%{style}\n" |
        while IFS=: read -r family style; do
            echo "${family%,*}${style:+:${style%,*}}"
        done | sort | uniq |
        fzf --reverse --cycle --preview "sh $0 {}" \
            --preview-window "left:$((WIDTH / 2)):noborder:wrap"
elif [ "$#" = 1 ]; then
    [ -p "$FIFO" ] && preview "$1"
fi