#!/usr/bin/env bash
set -Eeuo pipefail

end="\033[0m"
red="\033[0;31m"
red() { echo -e "${red}${1}${end}"; }


## Constant definitions

JSON="${1:-}"
[[ -z "${JSON}" ]] && {
  red 'Missing input JSON file.'
  cat <<EOF
Usage:
    $0 <SITE_JSON_PATH>

      Arguments
        SITE_JSON_PATH     Path to the site.json file which contains data and metadata about pages of the site.

Examples:
    $0 _site/site.json
    $0 result/site.json
    $0 \$(nix-build -A subtasks.docs)/site.json
EOF
  exit 2
}

LANGS=(en pt fr)
IGNORED_PAGES=(site.json sitemap.xml *.atom)


## Helper function definitions

contains-element() {
  local e match="$1"
  shift
  for e; do [[ "$e" == "$match" ]] && return 0; done
  return 1
}

fail-attr() {
  ATTRIBUTE="${1}"
  URL="${2}"
  red "Undefined '${ATTRIBUTE}' for ${URL}." >&2
  exit 1
}

get-lang() {
  echo "${1}" | base64 --decode | jq -r .lang
}

get-ref() {
  echo "${1}"  | base64 --decode | jq -r .ref
}

get-url() {
  # Remove leading / to match more closely the filesystem hierarchy
  echo "${1}"  | base64 --decode | jq -r .url | sed 's_^/__'
}

get-date() {
  echo "${1}"  | base64 --decode | jq -r .date
}

get-title() {
  echo "${1}"  | base64 --decode | jq -r .title
}

get-layout() {
  echo "${1}"  | base64 --decode | jq -r .layout
}


## Assertions

assert-frontmatter() {
  F="$1"
  DESIRED_LAYOUT="$2"
  PREFIX="${3:-}"
  LANG="$(get-lang "$F")"
  REF="$(get-ref "$F")"
  URL="$(get-url "$F")"
  LAYOUT="$(get-layout "$F")"

  [[ -z "${LANG}" ]] && fail-attr 'lang' "${URL}"
  [[ -z "${REF}" ]]  && fail-attr 'ref'  "${URL}"

  if ! contains-element "${URL}" "${IGNORED_PAGES[@]}"; then
    TITLE="$(get-title "$F")"
    [[ -z "${TITLE}" ]]  && fail-attr 'title' "${URL}"
  fi

  if ! contains-element "${LANG}" "${LANGS[@]}"; then
    red "Invalid lang '${LANG}' in ${URL}." >&2
    exit 1
  fi

  if [[ "${DESIRED_LAYOUT}" != "${LAYOUT}" ]]; then
    red "Layout mismatch: expected '${DESIRED_LAYOUT}', got '${LAYOUT}'."
    red "Page: ${URL}."
    exit 1
  fi

  if [[ -n "${PREFIX}" ]]; then
    DATE="$(get-date "$F" | awk '{print $1}')"
    URL_BASENAME="$(basename "$(get-url "$F")")"
    FILE="${PREFIX}/${DATE}-${URL_BASENAME%.html}.md"

    [[ -f "${FILE}" ]] || {
      red "date/filename mismatch: '${FILE}' does not exist. To fix, run:"
      echo "  mv '${PREFIX}/${URL_BASENAME%.html}.md' '${FILE}'"
      exit 1
    }
  fi
}

echo Linting articles... >&2
for article in $(jq -r '.articles[] | @base64' "${JSON}"); do
  assert-frontmatter "$article" 'post' '_articles'
done

echo Linting pages... >&2
for page in $(jq -r '.pages[] | @base64' "${JSON}"); do
  URL="$(get-url "$page")"
  if ! contains-element "${URL}" "${IGNORED_PAGES[@]}"; then
    assert-frontmatter "${page}" 'page'
  fi
done

echo Linting pastebins... >&2
for pastebin in $(jq -r '.pastebins[] | @base64' "${JSON}"); do
  assert-frontmatter "$pastebin" 'pastebin' '_pastebins'
done

echo Linting tils... >&2
for til in $(jq -r '.tils[] | @base64' "${JSON}"); do
  assert-frontmatter "$til" 'post' '_tils'
done

echo Asserting unique refs... >&2
KNOWN_IDS=()
assert-unique-ref() {
  for page in $1; do
    URL="$(get-url "$page")"
    if ! contains-element "${URL}" "${IGNORED_PAGES[@]}"; then
      LANG="$(get-lang "$page")"
      REF="$(get-ref "$page")"
      ID="${LANG}:${REF}"

      if contains-element "${ID}" "${KNOWN_IDS[@]}"; then
        printf '%s\n' "${KNOWN_IDS[@]}"
        red "Duplicated lang:ref match: '${ID}'." >&2
        red "Page: ${URL}." >&2
        exit 1
      fi

      KNOWN_IDS+=("${ID}") # printf '%s\n' "${KNOWN_IDS[@]}"
    fi
  done
}

assert-unique-ref "$(jq -r    '.pages[] | @base64' "${JSON}")"
assert-unique-ref "$(jq -r '.articles[] | @base64' "${JSON}")"
assert-unique-ref "$(jq -r     '.tils[] | @base64' "${JSON}")"

echo Done. >&2