#!/bin/sh

#
# This script creates a package version for packages.  The package
# version is the "release" or other version attached by the packaging
# software (eg, RPM or Dpkg) after the upstream software version.
#
# This software must be invoked like so:
#
#     svnrev.guess <packagename>
#
# and it expects that release tags are of the form:
#
#     /tags/<packagename>-<version>
#
# Note that release tag versioning expects a working connection to
# the repository (for SVN log), but all other branches don't require it.
#
# If there is no .svn directory or it cannot discover the repository
# version, the script sets a version of 0.local.
#

if [ $# -lt 1 ]
then
    echo "Usage: svnrev.guess <packagename>" >&2
    exit 1
fi
PACKAGE="$1"

getstat()
{
    if [ ! -d .svn ]
    then
        return
    fi
    svn stat -v | awk 'BEGIN{modified = "false";lastrev = 0}
                       /Status against/{next}
                       /^\?/{next} 
                       {
                         col1=substr($0, 0, 1);
                         if (col1 != " ") {modified = "true"}
                         sub(/^......../, "");
                         if ($1 > lastrev) { lastrev=$1 }
                       }
                       END{print modified,lastrev}'
}

#
# Branches that are not releases get a work-in-progress package version.
# This is 0.<svn_revision>[m].  The 0. ensures that an upcoming real
# release, with an package version of 1, will supercede this package.
# The "m" is added if the working tree has modifications to distinguish
# it from a committed revision.
#
# If there is no repository or there is a problem getting the revision,
# the package version is 0.local.
#
workingrev()
{
    STATINFO="$(getstat)"
    MODIFIED=$(echo "$STATINFO" | cut -f1 -d" ")
    LASTREV=$(echo "$STATINFO" | cut -f2 -d" ")

    if [ -z "$LASTREV" ]
    then
        PKG_VERSION=0.local
    else
        PKG_VERSION=0.${LASTREV}
        if [ "$MODIFIED" = "true" ]
        then
            PKG_VERSION="${PKG_VERSION}m"
        fi
    fi
    echo "$PKG_VERSION"
}

#
# If the branch is a tag (tags/project-x.y), it needs a release-based
# package version (-1, -2, etc).  Generally, it will be the tip of the
# branch (package version 1).  However, if there is a slight release
# fixup, that warrants bumping the package version.
#
# The logic is pretty simple.  Walk the history looking for the
# creation of the tag (A /tags/project-x.y).  For each revsion later
# than the creation of the tag, bump the package version.
# 
releaserev()
{
    BRANCH="$1"
    BRANCH_SEARCH="`echo "$BRANCH" | sed -e 's/\//\\\\\//g'`"
    svn log -v 2>&1 |
        awk 'BEGIN{rev=0}
             /^r[0-9]+ \|/{rev += 1}
             /^ +A \/'"$BRANCH_SEARCH"'$/{exit}
             /^ +A \/'"$BRANCH_SEARCH"' (.*)$/{exit}
             END{print rev}'
}


# 
# Tag branches are releases, and need a release-style package version.
# All other branches are non-release, and get an obviously
# work-in-progress package version.
#
# guessbranch() expects the standard Subversion layout of
#     /trunk
#     /branches/<branchname>
#     /tags/<tagname>
#
guessbranch()
{
    if [ ! -d .svn ]
    then
        return
    fi
    svn info | awk '/URL: .*\/trunk\/?$/{print "trunk"; exit 0}
                    /URL: .*\/branches\/[^/]+\/?/{
                                                   gsub(/\/$/, "", $2);
                                                   sub(/^.*\/branches\//, "", $2);
                                                   print "branches/"$2;
                                                   exit 0;
                                                 }
                    /URL: .*\/tags\/[^/]+\/?/{
                                                   gsub(/\/$/, "", $2);
                                                   sub(/^.*\/tags\//, "", $2);
                                                   print "tags/"$2;
                                                   exit 0;
                                                 }'
}

if ! which svn 1>/dev/null 2>&1
then
    echo "0.local"
else
    BRANCH=$(guessbranch)
    case "$BRANCH" in
    tags/${PACKAGE}*)
        releaserev "$BRANCH"
        ;;
    *)
        workingrev
        ;;
    esac
fi