#!/bin/bash

PROGNAME="$0"
DIR="$( cd "$( dirname "$(readlink -f "${BASH_SOURCE[0]}")" )" && pwd )"
ROOT="$(realpath "$DIR")"
CLEANCSS="$ROOT"/node_modules/clean-css-cli/bin/cleancss
LESSC="$ROOT"/node_modules/.bin/lessc
THEMES="light dark"
TARGETS="app"
INDIR=
OUTDIR=
TYPE=

error() {
    >&2 echo "error: $@"
}

die() {
    error "$@"
    exit 1
}

installed() {
    command -v "$1" > /dev/null
    return $?
}

usage() {
    cat <<EOF
usage: $PROGNAME [OPTIONS]

Options:
    -o  output directory
    -i  input directory
    -t  'less' or 'scss'
    -h  show this help
EOF
    exit
}

build() {
    local entry_name="$1"
    local theme="$2"

    local input="$INDIR/entries/$entry_name/$theme.$TYPE"
    local output="$OUTDIR/$entry_name"
    [ "$theme" = "dark" ] && output="${output}_dark"
    output="${output}.css"

    case "$TYPE" in
        less) "$LESSC" -x "$input" "$output" ;;
        scss) sassc -t compressed "$input" "$output" ;;
    esac
}

cleancss() {
    local entry_name="$1"
    local theme="$2"

    local file="$OUTDIR/$entry_name"
    [ "$theme" = "dark" ] && file="${file}_dark"
    file="${file}.css"

    "$CLEANCSS" -O2 "all:on;mergeSemantically:on;restructureRules:on" "$file" > "$file.tmp"
    rm "$file"
    mv "$file.tmp" "$file"
}

create_dark_patch() {
    local entry_name="$1"
    local light_file="$OUTDIR/$entry_name.css"
    local dark_file="$OUTDIR/${entry_name}_dark.css"

    "$DIR"/gen_css_diff.js "$light_file" "$dark_file" > "$dark_file.diff"
    rm "$dark_file"
    mv "$dark_file.diff" "$dark_file"
}

[ -z "$1" ] && usage

while [[ $# -gt 0 ]]; do
    case $1 in
        -o)
            OUTDIR="$2"
            shift
            ;;
        -i)
            INDIR="$2"
            shift
            ;;

        -t)
            case $2 in
                less|scss) TYPE="$2" ;;
                *) die "invalid type: $2" ;;
            esac
            shift
            ;;

        -h)
            usage
            ;;
        *)
            die "unexpected argument: $1"
            ;;
    esac
    shift
done

[ -z "$OUTDIR" ] && die "output directory is not specified"
[ -z "$INDIR" ] && die "input directory is not specified"
[ -z "$TYPE" ] && die "type is not specified"

if [ ! -d "$OUTDIR" ]; then
    mkdir "$OUTDIR"
else
    rm "$OUTDIR"/*
fi

[ -x "$CLEANCSS" ] || die "$CLEANCSS: cleancss not found"
case "$TYPE" in
    less) [ -x "$LESSC" ] || die "$LESSC: lessc not found" ;;
    scss) installed sassc || die "sassc not found" ;;
esac

for theme in $THEMES; do
    for target in $TARGETS; do
        build "$target" "$theme"
    done
done

for target in $TARGETS; do
    create_dark_patch "$target"
    for theme in $THEMES; do
        cleancss "$target" "$theme"
    done
done