#!/bin/sh
# 
# USAGE
#
#     rcs2git [FILES]
# 
# SUMMARY
#
#     Given an existing Git repository, this script imports the revision
#     history of a collection of RCS-controlled files.
#
# SYNOPSIS
#
#     Import the RCS revision history at ~/rcs-proj into a new Git
#     repository at ~/git-proj:
#
#         $ mkdir ~/git-proj
#         $ cd ~/git-proj
#         $ git init
#         $ cp -r ~/rcs-proj/RCS .
#         $ rcs2git
#         $ rm -rf RCS
#
#     Since no files were listed, rcs2git imports all files which match
#     *,v and RCS/*,v.
#
#     One can also import the history of a single RCS-controlled file
#     into an existing Git repository.  Here, we only create a symbolic
#     link to the RCS file:
#
#         $ cd ~/git-proj
#         $ ln -s ~/rcs-proj/RCS/file.ext,v
#         $ rcs2git file.ext
#         $ rm file.ext,v
#
# NOTES
#
#     This script does not recurse into subdirectories.  It assumes that
#     the RCS files (filename.ext,v) are present in the current
#     directory or the RCS directory.
#
#     This script does not preserve author information.  It assumes that
#     you are the sole author of the RCS project and that you have
#     correctly set your personal information in ~/.gitconfig.
#
# VERSION
#
#     1.00
# 
# LICENSE
#
#     Copyright (C) 2008 Jason Blevins <jrblevin@sdf.lonestar.org>
#
#     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.


# Outputs revision metadata in the form: file.ext 1.25 2008-03-30 19:24
store_metadata() {
    rlog $1 | sed -n "/^revision [0-9]*\.[0-9]*$/{
    s/^revision //g
    N
    s/\n/ /
    s/date: \([0-9 /]\{10\}\) \([0-9:]\{5\}\).*$/\1 \2/g
    s/\//-/g
    s/^/$1 /
    p
}"
}

# Imports a single revision into the Git repository.
import_revision() {
    file=$1
    rev=$2
    date=$3
    time=$4

    echo "=== $file $rev $date $time"

    # RCS checkout and log message
    co -r$rev -f $file &>/dev/null
    msg=$(rlog -r$rev $file | sed -n '/^date:/,$p' | tail -n +2 | head -n -1)
    echo -e "$msg\n"

    # Git commit
    GIT_AUTHOR_DATE="$date $time"
    GIT_COMMITTER_DATE="$date $time"
    export GIT_AUTHOR_DATE GIT_COMMITTER_DATE
    git add $file
    echo "$msg" | git commit -q -a -F - || true
}

# If no files are specified, search for all files under RCS control.
# That is, all files matching *,v and RCS/*,v.
if [[ $# < 1 ]]; then
    FILES=$(find . RCS/ -maxdepth 1 -name \*,v \
        | while read F ; do echo $(basename $F ,v ) ; done | tr -s '\n' ' ')
else
    FILES=$*
fi

# Create a temporary file for storing revision metadata
meta="/tmp/rcs2git-$$"

# Obtain revision metadata for each file
for f in $FILES; do
    store_metadata $f >> $meta
done

# Sort revision metadata by date (in place)
sort -k3,4 -o $meta $meta

# Process each revision
while read line; do
    file=$(echo $line | cut -f1 -d" ")
    rev=$(echo $line | cut -f2 -d" ")
    date=$(echo $line | cut -f3 -d" ")
    time=$(echo $line | cut -f4 -d" ")
    import_revision $file $rev $date $time
done < $meta

# Remove the temporary file
rm $meta