#!/bin/bash
#
# Download all ZWiki pages and push changes into
# the subversion repository.
#
PROG="$(basename $0)"


## costumize these settings to suit your environment

# URL to the Wiki frontpage; must have installed the
# DTML method from file ``list_all_pages.dtml``
ZWIKI_FRONTPAGE_URL='http://www.egrid.it/doc/gme/FrontPage'


## other settings, not for customization

# regular expression matching the way ZWiki reformats page titles
ZWIKI_PAGENAME_REGEX='^[A-Z][0-9A-Za-z]$'

# date for inclusion in the commit message
DATE="$(date -R)"


## useful functions

die () {
    local rc="$1"; shift
    echo -n "$PROG: "
    (if [ $# -gt 0 ]; then echo "$@"; else cat; fi) 1>&2
    exit $rc
}

have_command () {
    type -a "$1" >&/dev/null
}

require_command () {
    if ! have_command "$1"; then
        die 1 "Cannot find required command '$1' in the system PATH - aborting."
    fi
}


## generic VCS operations

vcs_is_checkout () {
    svn info >&/dev/null
}

vcs_register_file () {
    svn add "$1"
}

vcs_unregister_file () {
    svn rm --force "$1"
}

vcs_revert_file () {
    svn revert "$1"
}

vcs_commit_all () {
    local msg="$1"; shift
    svn commit -m "$msg"
}


## web interface

require_command curl
download () {
    local url="$1"
    local dest="${2:-$(basename $url)}"
    curl --silent --fail --show-error "$url" -o "$dest"
}


## main

# check that current working directory is a checkout
if ! vcs_is_checkout; then
    die 3 "Current directory '`pwd`' is not a repository checkout - aborting."
fi

# make a temporary file for holding page list
require_command mktemp
tmp="$(mktemp -t $PROG.XXXXXX)" \
    || die 1 "Cannot make temporary file - aborting."

# download page list
PAGE_LIST_URL="${ZWIKI_FRONTPAGE_URL}/list_all_pages"
download "$PAGE_LIST_URL" "$tmp" \
    || die 2 "Error downloading page list from '$PAGE_LIST_URL' - aborting."

# remove pages that no longer exist on the web from the repository.
for page in $(ls -1 [A-Z]* | egrep "$ZWIKI_PAGENAME_REGEX"); do
    if ! egrep -q "^$page" "$tmp"; then
        vcs_unregister_file "$page"
    fi
done

# push web changes into the repository
ZWIKI_BASE_URL="$(dirname $ZWIKI_FRONTPAGE_URL)"
(while read page; do
    # check if page is already in the repository,
    # otherwise assume it has been created on the web
    if test -e "$page"; then
        page_already_in_repo=yes
    else
        page_already_in_repo=no
    fi

    if download "${ZWIKI_BASE_URL}/${page}/text" "$page"; then
        if [ "$page_already_in_repo" = no ]; then
            vcs_register_file "$page"
        fi
    else
        # download failed for some reason,
        # make sure that no changes to this page
        # are committed to the repository
        if [ "$page_already_in_repo" = yes ]; then
            vcs_revert_file "$page"
        fi
    fi
done) <$tmp
rm -f "$tmp"

vcs_commit_all "snapshot by $PROG at $DATE"