#!/bin/bash

# Configuration options
STORAGE_PREFIX="/storage/md0"
HEADER="/data/sites/slackware.uk/html/search_header.html"
FOOTER="/data/sites/slackware.uk/html/search_footer.html"
LOCATEDB="/tmp/mirrors.db"
LIMIT=1000
MAX_CONCURRENT=5

# Extglob is required.
shopt -s extglob

# Output an error in processing.
die() {
  echo "<center><h2><b>Error: $1</b></h2><br></center>"
  exit 1
}

# A content type is required for CGI scripts.
echo -ne "Content-type: text/html\r\n\r\n"

# Include the header in the output.
# Note: The header cannot include PHP scripting.
cat "$HEADER"

# Limit the number of concurrent searches to avoid DoS.
if (( $(lsof -t "$LOCATEDB" | wc -l) > MAX_CONCURRENT - 1 )); then
  die "Too many concurrent searches - please try your search again in a few moments."
else
  exec 9<"$LOCATEDB" && flock -s -E 10 -w 2 9 || die "Too many concurrent searches - please try your search again in a few moments."
fi

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

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

  # Check the key is valid as a variable name.
  [[ ! "$KEY" =~ ^[[:alpha:]]+[[:digit:]_]*[[:alnum:]_]*$ ]] && die "Invalid key - please try your search again."

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

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

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

  # Define the variable from the key name.
  declare $KEY="$(echo -e "${_//+/ }")"
done <<<"${QUERY_STRING,,}&"

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

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

# HTML boilerplate.
cat <<EOF
    <center>
      <table class="header" align="center">
        <tr>
          <td align="center">
            <font size="+2"><b>Showing search results for: $Q_COPY</b></font><br><br>
            Searches may contain multiple terms, include (basic) globs, and descend down from the current directory.
          </td>
        </tr>
      </table>
    </center>
    <table width="95%">
      <tr>
        <td class="navbar">
        </td>
        <td class="search" align="right" valign="bottom">
          <form action="/search">
            <input type="hidden" name="p" value="$p">
            <input class="searchinput" alt="Search:" title="Search" type="text" name="q" placeholder="Search" value="$Q_COPY">
<!--        <button class="searchbutton" type="submit" href="#"><img src="https://slackware.uk/html/search.png" height="15"></button> -->
          </form>
        </td>
      </tr>
    </table>
    <table class="searchresults" align="center" width="90%">
      <tr>
        <td>
          <hr>
          <code>
EOF

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

  # Remove paths we don't want the user to see.
  [[ "${REPLY/$STORAGE_PREFIX}" =~  ^/\.sandbox.* ]] && continue
  [[ "${REPLY/$STORAGE_PREFIX}" =~  ^/\.lftp.* ]] && continue
  [[ "${REPLY/$STORAGE_PREFIX}" =~  ^/dead\.letter ]] && continue
  [[ "${REPLY/$STORAGE_PREFIX}" =~  .*\.rsync-tmp.* ]] && continue

  # List the item.
  echo "            &bull; <a href=\"${REPLY/$STORAGE_PREFIX}\" title=\"${REPLY/$STORAGE_PREFIX}\" alt=\"${REPLY/$STORAGE_PREFIX}\">${REPLY/$STORAGE_PREFIX}</a><br>"

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

# If there's no results, tell the user.
if (( COUNT == 0 )); then
  echo "            No results - try to widen your search."
elif (( COUNT == LIMIT )); then
  echo "            Maximum $LIMIT items shown - try to refine your search."
else
  echo "            $COUNT items found."
fi

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

# Include footer.
cat "$FOOTER"