#!/bin/sh

# Accepts two argument: the git reference (SHA-1 hash) that
# corresponds to the current state of the Perforce repository.

# Assumption: we are in the folder where the Perforce repository is
# located and the paths that git will provided, when stripped of one
# initial folder (e.g. a/b/c/d => b/c/d) will correctly reference
# the files.

if [ $# -lt 2 ] ; then
   echo "usage: $0 SHA-1-describing-perforce /path/to/git/repo"
   exit 1
fi

dry_run="--dry-run"

while true ; do
    case $1 in
        -l|--live) dry_run= ; shift ;;
        *) break ;;
    esac
done

# Now check argument list again

if [ $# -lt 2 ] ; then
   echo "usage: $0 SHA-1-describing-perforce /path/to/git/repo"
   exit 1
fi

earliest=$1
gitdir=$2

if [ ! -d $gitdir ] ; then
   echo "Git repository $gitdir does not exist or is not a directory"
   exit 1
fi

if [ ! -d $gitdir/.git ] ; then
    echo "Git repository $gitdir does not appear to be a git repository (no .git folder)"
    exit 1
fi

#
# Let the user know what is about to happen
#

if [ x$dry_run != x ] ; then
    echo "This will be a DRY RUN. No files will be modified. Press enter to continue"
else
    echo "This will be a live run. Files WILL be modified. Press enter to continue"
fi
read

#
# get a list of commits since $earliest (i.e. everything not yet present in the Perforce repo
#

commitlist=`(cd $gitdir && git log --reverse $earliest..HEAD) | grep '^commit' | cut -d' ' -f2`

for commit in $commitlist ; do
    printf "Next revision:

      $(cd $gitdir && git log --pretty=oneline -n 1 $commit). 

Press enter to try to apply this change:"

    read

    while [ true ] ; do 
        if (cd $gitdir && git show $commit) | patch -p1 $dry_run ; then
            echo "Completed successfully."
            break;
        else
            echo "Git commit $commit did not apply cleanly."
            printf "Type s to skip, w to wait (while you fix it) or enter to stop this merge: "
            read r
            case $r in
                s|S) break;
                    ;;
                w|W) printf "OK, type enter when you're ready to continue or anything else to quit: "
                    read rr
                    if [ x$rr != x ] ; then
                        echo "The commit that you stopped before merging was " $commit
                        exit 1
                    fi
                    ;;
                *) echo "When you restart, remember to use $commit as the first argument to this script."
                    exit 1
                    ;;
            esac
        fi
    done
done

echo "The Perforce workspace at `pwd` is now current with the git repository at $gitdir"
exit 0