#!/bin/sh
#
# = trac-svn-hook =
#
#  Purpose:: this script is meant to be called from the Subversion hooks
#            for notifying Trac when changesets are added or modified.
#
#  Scope:: The http://trac.edgewall.org/wiki/TracRepositoryAdmin page
#          describes how to directly call the relevant trac-admin commands
#          from the Subversion hooks. In most cases this should be enough,
#          however this script should make troubleshooting easier and
#          has support for notifying multiple Trac environments.
#
#  Usage:: copy this script to some central place, for example in your
#          TRAC_ENV or TRAC_PARENT_ENV folder
#          **Be sure to read the Configuration Notes section below first**
#          then fill in the variables listed below the Configuration section.
#
# For each Subversion repository $REPOS that has to be monitored by
# your Trac environment(s), you need to modify the hooks in order to
# call the present script:
#
# Add this to your `$REPOS/hooks/post-commit` script:
#
#     /path/to/trac-svn-hook $REPOS $REV
#
# If you allow revision property editing in `$REPOS/hooks/pre-revprop-change`,
# then you can let Trac know about modified changesets by adding the following
# lines to the `$REPOS/hooks/post-revprop-change` script:
#
#     if [ "$PROPNAME" = "svn:log" -o "$PROPNAME" = "svn:author" ]; then
#         /path/to/trac-svn-hook $REPOS $REV $USER $PROPNAME
#     fi
#
# See also http://svnbook.red-bean.com/en/1.5/svn.reposadmin.create.html#svn.reposadmin.create.hooks
#
#  Platform:: Unix or Cygwin.
#
# On Windows, if you have Cygwin installed, you can also use this
# script instead of the `trac-svn-hook.cmd`.
# In your `post-commit.bat` and `post-revprop-change.bat` hooks, call
# this script using:
#
#     bash /path/to/trac-svn-hook "%1" "%2" "%3" "%4"
#
# -----------------------------------------------------------------------------
#
# == Configuration
#
# Uncomment and adapt to your local setup:
#
# export TRAC_ENV=/path/to/trac-env:/path/to/another/trac-env
# export PATH=/path/to/python/bin:$PATH
# export LD_LIBRARY_PATH=/path/to/python/lib:$LD_LIBRARY_PATH
#
# -----------------------------------------------------------------------------
#
# == Configuration Notes
#
# As a preliminary remark, you should be aware that Subversion usually
# run the hooks in a very minimal environment.
# This is why we have to be very explicit about where to find things.
#
# According to http://subversion.apache.org/faq.html#hook-debugging,
# one useful method for getting the post-commit hook to work is to call
# the hook manually from a shell, as the user(s) which will end up running
# the hook (e.g. wwwrun, www-data, nobody). For example:
#
#     env - $REPOS/hooks/post-commit $REPOS 1234
#
# or:
#
#     env - $REPOS/hooks/post-revprop-change $REPOS 1234 nobody svn:log
#
#
# The environment variables that have to be set in this script are
# TRAC_ENV, PATH and eventually LD_LIBRARY_PATH.
#
#  TRAC_ENV:: the path(s) to the Trac environment(s)
#
# In case you need to maintain more than one environment in sync with
# the repository (using a different scope or not), simply specify more
# than one path, using the ":" path separator (or ";" if the script is
# used on Windows with Cygwin's bash - in this case also don't forget to
# enclose the list of paths in quotes, e.g. TRAC_ENV="path1;path2").
#
# Note that if you have to maintain multiple repositories and multiple Trac
# environments, and you have some non-trivial mapping between repositories
# and Trac environments, then you can leave the TRAC_ENV setting out of
# this file and put it directly in your post-commit and post-revprop-change
# hooks, so that the changes to each repositories are notified to the
# appropriate environments (don't forget to export TRAC_ENV in this case).
#
#  PATH:: the folder containing the trac-admin script
#
# This folder is typically the same as your Python installation bin/ folder.
# If this is /usr/bin, then you probably don't need to put it in the PATH.
#
# Note that if you're using a python program installed in a non-default
# location (such as /usr/local or a virtual environment), then you need
# to add it to the PATH as well.
#
#  LD_LIBRARY_PATH:: folder(s) containing additional required libraries
#
# You may also need to setup the LD_LIBRARY_PATH accordingly.
# The same goes for any custom dependency, such as SQLite libraries or
# SVN libraries: make sure everything is reachable.
# For example, if you get errors like "global name 'sqlite' is not defined"
# or similar, then make sure the LD_LIBRARY_PATH contains the path to all
# the required libraries (libsqlite3.so in the above example).
#
#
# -----------------------------------------------------------------------------
#
# == Examples
#
# === Minimal setup example ===
#
# Python is installed in /usr/bin, Trac was easy_install'ed.
#
# {{{
# export TRAC_ENV=/srv/trac/the_trac_env
# }}}
#
#
# === Virtualenv setup example ===
#
# Here we're using a Trac installation set up using virtualenv
# (http://pypi.python.org/pypi/virtualenv).
#
# In this example, the virtualenv is located in
# /packages/trac/branches/trac-multirepos
# and is based off a custom Python installation (/opt/python-2.4.4).
# We're also using a custom SQLite build (/opt/sqlite-3.3.8).
#
# Note that virtualenv's activate script doesn't seem to care
# about LD_LIBRARY_PATH and the only other thing it does and that
# we need here is to set the PATH, we can as well do that ourselves:
#
# We also want to notify two Trac instances:
#
# {{{
# export TRAC_ENV=/srv/trac/the_trac_env:/srv/trac/trac_other_trac_env
# export PATH=/packages/trac/branches/trac-multirepos/bin:$PATH
# export LD_LIBRARY_PATH=/opt/python-2.4.4/lib:/opt/sqlite-3.3.8/lib:$LD_LIBRARY_PATH
# }}}
#
#
# === Cygwin setup example ===
#
# {{{
# export TRAC_ENV=C:/Workspace/local/trac/devel
# export PYTHONPATH=C:/Workspace/src/trac/repos/multirepos
# export PATH=/C/Dev/Python261/Scripts:$PATH
# }}}
#
# -----------------------------------------------------------------------------
#
# This is the script itself, you shouldn't need to modify this part.

# -- Command line arguments (cf. usage)

REPOS="$1"
REV="$2"
USER="$3"
PROPNAME="$4"

# -- Foolproofing

if [ -z "$REPOS" -o -z "$REV" ]; then
    echo "Usage: $0 REPOS REV"
    exit 2
fi

if ! python -V 2>/dev/null; then
    echo "python is not in the PATH ($PATH), check PATH and LD_LIBRARY_PATH."
    exit 2
fi

if [ -z "$TRAC_ENV" ]; then
    echo "TRAC_ENV is not set."
    exit 2
fi

# -- Feedback

echo "----"

if [ -z "$USER" -a -z "$PROPNAME" ]; then
    EVENT="added"
    echo "Changeset $REV was added in $REPOS"
else
    EVENT="modified"
    echo "Changeset $REV was modified by $USER in $REPOS"
fi

# -- Call "trac-admin ... changeset ... $REPOS $REV" for each Trac environment

ifs=$IFS
IFS=:
if [ -n "$BASH_VERSION" ]; then # we can use Bash syntax
    if [[ ${BASH_VERSINFO[5]} = *cygwin ]]; then
        IFS=";"
    fi
fi
for env in $TRAC_ENV; do
    if [ -r "$env/VERSION" ]; then
        log=$env/log/svn-hooks-`basename $REPOS`.log
        nohup sh <<EOF >> $log 2>&1 &
            echo "Changeset $REV $EVENT"
            trac-admin $env changeset $EVENT $REPOS $REV && \
                echo "OK" || echo "FAILED: see the Trac log"
EOF
    else
        echo "$env doesn't seem to be a Trac environment, skipping..."
    fi
done
IFS=$ifs

