#!/bin/bash

# Configuration options
BASE_DIR="/data/sites"
STORAGE_PREFIX="/storage/md0"
IGNORE_REGEXES=('^/\.sandbox.*' '^/\.lftp.*' '^/dead\.letter' '.*\.rsync-tmp.*')
HEADER_DARK="$BASE_DIR/${SERVER_NAME:-slackware.uk}/html/includes/search-header-dark.html"
FOOTER_DARK="$BASE_DIR/${SERVER_NAME:-slackware.uk}/html/includes/search-footer-dark.html"
HEADER_LIGHT="$BASE_DIR/${SERVER_NAME:-slackware.uk}/html/includes/search-header-light.html"
FOOTER_LIGHT="$BASE_DIR/${SERVER_NAME:-slackware.uk}/html/includes/search-footer-light.html"
LOCATEDB="/tmp/mirrors.db"
LIMIT=1000
MAX_CONCURRENT=5

# Extglob is required.
shopt -s extglob

# Output an error in processing.
die() {
  # $1 = The error message to output.
  # $2 = Whether to include the retry link ("false" to disable inclusion, everything else is true).
  cat <<EOF
    <br><br>
    <center>
      <table class="header" align="center">
        <tr>
          <td align="center">
            <b class="subheading">Error: $1</b>$([[ "${2,,}" != "false"  ]] && printf "<br>\n            Please click <a href=\"%s\" title=\"Retry Search\">here</a> to retry your search." "${REQUEST_SCHEME:-https}://${SERVER_NAME:-slackware.uk}/search?$QUERY_STRING")
          </td>
        </tr>
      </table>
    </center>
  </body>
</html>
EOF
  exit 1
}

# Initial headers.
printf "%s: %s\\n" "Content-type" "text/html"
printf "%s: %s\\n" "Cache-Control" "no-cache, no-store, must-revalidate"
printf "%s: %s\\n" "Pragma" "no-cache"
printf "%s: %s\\n\\n" "Expires" "1"

# Extract cookies.
while read -r -d " " RAW; do
  KEY="${RAW%%=*}"
  VALUE="${RAW#*=}"
  declare -A COOKIES+=( ["${KEY,,}"]="${VALUE,,}" )
done <<<"$HTTP_COOKIE "	# The space at the end is required.

# Include the themed header.
if [[ "${COOKIES['theme']}" == "dark" ]]; then
  cat "$HEADER_DARK"
else
  cat "$HEADER_LIGHT"
fi

# Limit the number of concurrent searches to avoid DoS.
if (( $(lsof -t "$LOCATEDB" | wc -l) > (MAX_CONCURRENT - 1) )); then
  die "too many concurrent searches!"
else
  exec 9<"$LOCATEDB" && flock -s -E 10 -w 2 9 || die "too many concurrent searches!"

  while read -r -d '&' QUERY; do
    # If the read returned an empty string, skip.
    [[ -z "$QUERY" ]] && continue

    # Extract the key and value to temporary variables.
    KEY="${QUERY%%=*}"
    VALUE="${QUERY#*=}"

    # Check the key is valid as a variable name.
    [[ ! "$KEY" =~ ^[[:digit:]_]*[[:alnum:]_]*$ ]] && die "invalid query - don't try to be clever :)" "false"

    # Remove spaces from beginning and end of value.
    : "${VALUE/#+(+)}"
    : "${_/%+(+)}"

    # Squash multiple spaces in value.
    : "${_//+(+)/+}"

    # Convert values from %-encoded form.
    : "${_//%/\\x}"

    # Define the variable from the key name.
    declare "X_$KEY"="$(printf "%b" "${_//+/ }")"
  done <<<"${QUERY_STRING,,}&"	# The & at the end is required.

  # Take a copy of q before it's modified, for the heading.
  Q_COPY="${X_q:-(empty)}"

  # Adjust 'X_q' for the locate command by wrapping search elements in *s.
  : "*${X_q// /* *}*"
  X_q="${_//\/*/*}"

  # HTML boilerplate.
  cat <<EOF
    <center>
      <table class="header" align="center">
        <tr>
          <td align="center">
            <b class="heading">Search Results</b><br><br>
            <b class="subheading">Search query: $Q_COPY</b><br>
            Searches may contain multiple terms, include (basic) globs,<br>
            and descend down from the current directory.
          </td>
        </tr>
      </table>
    </center>
    <table width="90%" align="center" cellspacing="15">
      <tr>
        <td class="search" align="right" valign="center">
          <form action="/search">
            <input type="hidden" name="p" value="$X_p">
            <input class="searchinput" title="Search" alt="Search Box" type="text" name="q" value="$Q_COPY" autocomplete="on" required>
          </form>
        </td>
        <td width="100%">
          <!-- This cell is intentionally empty -->
        </td>
        <td class="search" align="left" valign="center">
          <a href="/html/toggletheme.php" title="Toggle Theme" alt="Toggle Theme"><img src="/html/toggletheme.png" title="Toggle Theme" alt="Toggle Theme"></a>
        </td>
      </tr>
      <tr>
        <td class="searchresults" colspan="3">
          <hr>
          <code>
EOF

  I=1
  COUNT=0
  while read -r ITEM; do
    # Only show 1000 items to prevent long load times.
    (( I == LIMIT + 1 )) && break

    # Remove paths we don't want the user to see.
    while read -r -d " " REGEX; do
      [[ "${ITEM/$STORAGE_PREFIX}" =~  $REGEX ]] && continue 2
    done <<<"${IGNORE_REGEXES[@]}"

    # List the item.
    printf "            &bull; <a href=\"%s\" title=\"%s\">%s</a><br>\\n" "${ITEM/$STORAGE_PREFIX}" "${ITEM/$STORAGE_PREFIX}" "${ITEM/$STORAGE_PREFIX}"

    (( I++ ))
    (( COUNT++ ))
  done < <(locate -A -d "$LOCATEDB" -i -l "$(( LIMIT * 2 ))" "$STORAGE_PREFIX/${X_p##/}" $X_q | sort)

  # Tell the user about the results.
  if (( COUNT == 0 )); then
    printf "            %s" "No results - try to widen your search."
  elif (( COUNT == LIMIT )); then
    printf "            %s" "Maximum $LIMIT items shown - try to refine your search."
  else
    printf "            %s" "$COUNT items found."
  fi

# HTML boilerplate.
  cat <<EOF
          </code>
          <hr>
        </td>
      </tr>
    </table>
EOF

  # Include footer.
  if [[ "${COOKIES['theme']}" == "dark" ]]; then
    cat "$FOOTER_DARK"
  else
    cat "$FOOTER_LIGHT"
  fi
fi