#!/bin/sh

# Description:
#   Try hard to identify the current revision of the code.
#   Works for Git and the Github SVN bridge.
#   For a SVN sandbox, requires connection to (and authentication
#   with) the server.
# Usage:
#   pc_identify_revision [--reset|-r] [--print-file-name|-p]
# Examples:
#   pc_identify_revision                    # Write revision file
#   pc_identify_revision --reset            # Delete revision file
#   pc_identify_revision --print-file-name  # print name of rev. file

revision_file='revision.txt'
quiet=''                        # set to '1' to suppress diff output


check_prerequisites () {
    # Sanity checks.
    # Some of these requirements could be weakened, but it is better
    # to play safe.
    if [ -z $PENCIL_HOME ]; then
        echo "Error: \$PENCIL_HOME must be set."
        exit 1
    fi
}


write_revision_file () {
    echo 'Revision:' >> ${revision_file}
    echo '---------' >> ${revision_file}

    if [ -d "${PENCIL_HOME}/.git" ]; then
        write_revision_file_from_git_sandbox
    elif [ -d "${PENCIL_HOME}/.svn" ]; then
        write_revision_file_from_svn_sandbox
    else
        echo 'Warning: Cannot determine a revision number' \
            >> ${revision_file}
    fi
    echo >> ${revision_file}
}


write_revision_file_from_git_sandbox () {
    git_cmd rev-parse HEAD >> ${revision_file}
    git_cmd log --format='%B' -n 1 HEAD >> ${revision_file}
    echo >> ${revision_file}

    # Not relevant for now, but nice with annotated release tags:
    #   git_cmd describe HEAD >> ${revision_file}

    # Append the output from 'git status', so we know whether
    # there were uncommitted changes:
    echo 'Git status:' >> ${revision_file}
    echo '-----------' >> ${revision_file}
    git_cmd status >> ${revision_file}
    echo >> ${revision_file}

    if [ -z $quiet ]; then
        # For a complete record: document any local changes
        echo 'Git diff:' >> ${revision_file}
        echo '---------' >> ${revision_file}
        git_cmd diff HEAD >> ${revision_file}
        echo >> ${revision_file}
    fi
}


write_revision_file_from_svn_sandbox () {
    # SVN revision:
    svn_cmd log --limit 1 >> ${revision_file}
    echo >> ${revision_file}

    # Which branch we are on
    svn_cmd info >> ${revision_file}

    # Git revision.
    # Somewhat tricky, because this command requires
    # authentication with the server, which may not be
    # possible in automated test runs.
    # Thus, we run this with a timeout of 1 minute:
    echo "Git revision:" >> ${revision_file}
    time_limited_svn_cmd propget git-commit --revprop -r HEAD \
        https://github.com/pencil-code/pencil-code.git \
        >> ${revision_file}
    echo >> ${revision_file}

    # Append the output from 'svn status', so we know whether
    # there were uncommitted changes:
    echo "SVN status:" >> ${revision_file}
    svn_cmd status >> ${revision_file}
    echo >> ${revision_file}

    if [ -z $quiet ]; then
        # For a complete record: document any local changes
        echo "SVN diff:" >> ${revision_file}
        svn_cmd diff >> ${revision_file}
        echo >> ${revision_file}
    fi
}


git_cmd () {
    # Run a git command from the top directory
    (cd $PENCIL_HOME; git "$@")
}


svn_cmd () {
    # Run a SVN command from the top directory
    (cd $PENCIL_HOME; svn "$@")
}

time_limited_svn_cmd () {
    # Run a SVN command from the top directory with a time limit of 1
    # minute
    (cd $PENCIL_HOME; timeout 30s svn "$@" || echo "Timed out: 'svn $@'")
}


main () {
    if [ "$1" = "--print-file-name" -o "$1" = "-p" ]; then
        echo "${revision_file}"
        exit 0
    elif [ "$1" = "--reset" -o "$1" = "-r" ]; then
        write_file=''
    else
        write_file=1
    fi

    check_prerequisites
    rm -f ${revision_file}

    if [ $write_file ]; then
        write_revision_file
    fi
}


main "$@"