#!/bin/bash
#
# html_updateHeadings.sh -- This function transforms html headings to
# to make them accessible (e.g., through a table of contents).
#
#   - In order for this function to work, you need to put headings in
#     just one line and they must have the following formats:
#
#       <h1><a name="">Title</a></h1>
#       <h1><a href="">Title</a></h1>
#       <h1><a name="" href="">Title</a></h1>
#
#     In the above examples, h1 alternates from h1 to h6. Closing tag
#     must be present and match the one opening. The value of <a
#     name=""> and <a href=""> options are the md5sum of page
#     location, plus the 'head-' string, plus the heading string. If
#     heading title or page location changes, the values of <a
#     name=""> and <a href=""> options will change too.
#
# Copyright (C) 2009-2010 Alain Reguera Delgado
# 
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
# USA.
# 
# ----------------------------------------------------------------------
# $Id$
# ----------------------------------------------------------------------

function html_updateHeadings {

    # Define variables as local to avoid conflicts outside.
    local FILES=''
    local COUNT=0
    local PREVCOUNT=0
    local PATTERN=''
    local -a FINAL
    local -a TITLE
    local -a MD5SM
    local -a OPTNS
    local -a LEVEL
    local -a PARENT

    # Define list of html files to process using option value as
    # reference. 
    if [[ -d $OPTIONVAL ]];then
        FILES=$(find $OPTIONVAL -regextype posix-egrep -type f -regex '.*/*.(html|htm)$')
    elif [[ -f $OPTIONVAL ]];then
        FILES=$OPTIONVAL
    fi

    for FILE in $FILES;do

        # Verify list of html files. Are they really html files? If
        # they don't, continue with the next one in the list.
        if [[ ! $(file --brief $FILE) =~ '^(XHTML|HTML|XML)' ]];then
            continue
        fi

        # Output action message.
        #cli_printMessage $FILE 'AsUpdatingLine'

        # Define html heading regular expression. Use parenthisis to save
        # html option name, option value, and heading title.
        PATTERN="<h([1-9])>(<a.*[^\>]>)(.*[^<])</a></h[1-9]>"

        # Define list of headings to process. When building the
        # heading, it is required to change spaces characters from its
        # current output form to something different (e.g., its \x040
        # octal alternative). This is required because the space
        # character is used as egrep default field separator and
        # spaces can be present inside heading strings we don't want
        # to separate.
        for HEADING in $(egrep "$PATTERN" $FILE \
            | sed -r -e 's!^[[:space:]]+!!' -e "s! !\x040!g");do

            # Define previous counter value using current counter
            # value as reference.
            if [[ $COUNT -ne 0 ]];then
                PREVCOUNT=$(($COUNT-1))
            fi

            # Define initial heading information.
            FIRST[$COUNT]=$(echo $HEADING | sed -r "s!\x040! !g")
            TITLE[$COUNT]=$(echo ${FIRST[$COUNT]} | sed -r "s!$PATTERN!\3!")
            MD5SM[$COUNT]=$(echo "${FILE}${FIRST[$COUNT]}" | md5sum | sed -r 's![[:space:]]+-$!!')
            OPTNS[$COUNT]=$(echo ${FIRST[$COUNT]} | sed -r "s!$PATTERN!\2!")
            LEVEL[$COUNT]=$(echo ${FIRST[$COUNT]} | sed -r "s!$PATTERN!\1!")
            PARENT[$COUNT]=${LEVEL[$PREVCOUNT]}

            # Transform heading information using initial heading
            # information as reference.
            if [[ ${OPTNS[$COUNT]} =~ '^<a (href|name)=".*[^"]" (href|name)=".*[^"]">$' ]];then
                OPTNS[$COUNT]='<a name="head-'${MD5SM[$COUNT]}'" href="#head-'${MD5SM[$COUNT]}'">'
            elif [[ ${OPTNS[$COUNT]} =~ '^<a name=".*[^"]">$' ]];then 
                OPTNS[$COUNT]='<a name="head-'${MD5SM[$COUNT]}'">'
            elif [[ ${OPTNS[$COUNT]} =~ '^<a href=".*[^"]">$' ]];then
                OPTNS[$COUNT]='<a href="#head-'${MD5SM[$COUNT]}'">'
            fi

            # Build final html heading structure.
            FINAL[$COUNT]='<h'${LEVEL[$COUNT]}'>'${OPTNS[$COUNT]}${TITLE[$COUNT]}'</a></h'${LEVEL[$COUNT]}'>'

            # Build html heading link structure.
            LINK[$COUNT]='<a href="#head-'${MD5SM[$COUNT]}'">'${TITLE[$COUNT]}'</a>'

            # Build table of contents entry with numerical
            # identifications.
            TOCENTRIES[$COUNT]="$COUNT:${LEVEL[$COUNT]}:${PARENT[$COUNT]}:${LINK[$COUNT]}"

            # Update heading information using the first and last
            # heading structures.
            #sed -i -r "s!${FIRST[$COUNT]}!${FINAL[$COUNT]}!" $FILE

            # Increase heading counter.
            COUNT=$(($COUNT + 1))

        done

        # Reset heading counter.
        COUNT=0

        # Use awk to build the table of content.
        for TOC in "${TOCENTRIES[@]}";do
            echo $TOC
        done \
            | awk 'BEGIN{FS=":"}{printf "%s\n", $4}'

    done

}