#!/bin/sh
set -eu

if [ "$#" -lt 2 ] ; then
  echo "Usage: $0 <base domain> <emoji pack name> [<conditional addition>]" >&2
  exit 2
fi

DOMAIN="$1"
CATEGORY="$2"
ADDCOND="${3:-}"

OVERWRITE_IMG="${OVERWRITE_IMG:-NO}"
OVERWRITE_METAKEYS="${OVERWRITE_METAKEYS:-NO}"

json_str_escape() {
  echo "$1" | sed -e 's/"/\\"/g'
}

CACHE_DIR="$(dirname "$0")"/.cache
cached_list="$CACHE_DIR"/"$(date -I)_${DOMAIN}"

if [ ! -e "$cached_list" ] ; then
  mkdir -p "$CACHE_DIR"
  curl https://"$DOMAIN"/api/v1/custom_emojis | jq > "$cached_list"
fi

# Track additions in "pack.json".files format
META_ADD="$(mktemp)"
meta_prefix="{"

# @tsv doesn't actually directly produce TSV, but for each line a string which escapes tabs as \t...
cat "$cached_list" \
  | jq '.[] | select(.category == "'"$CATEGORY"'"'"${ADDCOND:+ }${ADDCOND}"') | [.shortcode, .static_url] | @tsv' \
  | awk '1 {gsub(/^"|"$/, ""); sub(/\\t/, "\t"); print}' \
  | while IFS="$(printf '\t')" read -r name url; do
      urlfile="$(basename "$url")"
      ext="${urlfile##*.}";
      if [ "$ext" = "$urlfile" ] ; then
        ext=""
      fi

      if [ "$name" != "$(basename "$name")" ] ; then
        echo "ERROR: unsafe, potentially malicious shortcode '$name'; aborting!"
        exit 1
      fi

      out="${name}${ext:+.}${ext}"
      if [ "$OVERWRITE_IMG" = "YES" ] || [ ! -e "$out" ] ; then
        echo "Downloading $out ..."
        wget --quiet --output-document="$out" "$url"
        printf '%s\n\t"%s": "%s"' "$meta_prefix" \
          "$(json_str_escape "$name")" "$(json_str_escape "$out")" \
          >> "$META_ADD"
        meta_prefix=","
      fi
    done

if [ "$meta_prefix" = "{" ] ; then
  echo "No emoji matched search criteria"
  rm "$META_ADD"
  exit 0
fi
printf '\n}\n' >> "$META_ADD"

cnt_dl="$(jq '. | length' "$META_ADD")"
echo "Finished downloading $cnt_dl images."

if [ ! -e pack.json ] ; then
  printf '{"files": {}, "files_count": 0, "pack": {"description": "%s: %s%s%s"}}' \
    "$(json_str_escape "$DOMAIN")" \
    "$(json_str_escape "$CATEGORY")" \
    "${ADDCOND:+ }" \
    "$(json_str_escape "$ADDCOND")" \
    > pack.json
fi

cnt_old="$(jq '.files | length' pack.json)"
echo "Found $cnt_old preëxisting emoji."

new_files="$(
  if [ "$OVERWRITE_METAKEYS" = "YES" ] ; then
    jq --sort-keys -s '.[0].files + .[1]' pack.json "$META_ADD"
  else
    jq --sort-keys -s '.[0] + .[1].files' "$META_ADD" pack.json
  fi
)"
echo "$new_files" > "$META_ADD"

cnt_new="$(jq '. | length' "$META_ADD")"
cnt_diff=$((cnt_new - cnt_old))
echo "After merging there are a total of $cnt_new emoji."
if [ "$cnt_diff" != "$cnt_dl" ] ; then
  echo "WARNING: expected a gain of $cnt_dl but got $cnt_diff additional entries!"
  echo "         (the existing pack may not follow the expected filename scheme)"
fi

jq --argjson new_files "$new_files" \
   --arg cnt_new "$cnt_new" \
   '.files = $new_files | .files_count = $cnt_new' \
   pack.json \
   > "$META_ADD"

mv "$META_ADD" pack.json