#!/bin/bash
# SPDX-License-Identifier: GPL-2.0-only

#  (kgit-checkpoint), (checkpoint and restore for meta-information)

#  Copyright (c) 2008-2012 Wind River Systems, Inc.

#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License version 2 as
#  published by the Free Software Foundation.

#  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.

#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

# For consistent behaviour with "grep -w"
LC_ALL=C
export LC_ALL

usage()
{
cat <<EOF

 kgit-checkpoint -b <target checkpoint branch> 
                 [-c] [-r] [-d] [-v] <action>
 
   -b:  branch that stores checkpointed files
   -r:  restore checkpoint commit
   -c:  create a checkpoint commit
   -m:  checkpoint message (the date will be used if not supplied)
   -v:  verbose 

   <action>: 'restore' or 'create'. equivalent to -r and -c

EOF
}

# command line processing
while [ $# -gt 0 ]; do
	case "$1" in
                -b|--b)
                        cmd_branch=$2
                        shift
                        ;;
                -m|--m)
                        checkpoint_msg="$2"
                        shift
                        ;;
	        -v|--v)
                        verbose=t
                        ;;
	        -r|--r)
                        restoring=t
			checkpointing=
                        ;;
	        -c|--c)
                        restoring=
			checkpointing=t
                        ;;
	        -h|--h)
                        usage
			exit
                        ;;
	        -*)   
                        usage
			exit
			;;
		*)
			break
			;;
	esac
	shift
done

if [ -z "$1" ] ; then
    if [ -z "$checkpointing" ] && [ -z "$restoring" ]; then
	usage
	exit
    fi
fi

# source utility functions
. `dirname $0`/kgit

action=$@
case $action in
    create)
	restoring=
	checkpointing=t
	;;
    restore)
	restoring=t
	checkpointing=
	;;
esac

if [ ! -d .git ]; then
    echo "ERROR. Not a git repository"
    exit 1
fi

# set some defaults
if [ -z "$checkpoint_msg" ]; then
    checkpoint_msg="checkpoint: `date`"
fi

# save this so we can go back later ...
current_branch=`get_current_git_branch`
checkpoint_branch=

get_meta_dir()
{
    meta_branch=$1

    # if there's already a located and logged meta directory, just use that and
    # return. Otherwise, we'll look around to see what we can find.
    if [ -f ".metadir" ]; then
        md=`cat .metadir`
        echo $md
        return
    fi

    # determine the meta directory name
    meta_dir_options=`git ls-files -o --directory`
    for m in $meta_dir_options; do
	if [ -d "$m/cfg" ]; then
	    md=`echo $m | sed 's%/%%'`
	fi
    done

    # store our results where other scripts can quickly find the answer
    if [ -n "$md" ]; then
        echo "$md" > .metadir
    fi

    # return the directory to he caller
    echo $md
}

checkpoint_branch=$KMETA
if [ -n "$cmd_branch" ]; then
    checkpoint_branch=$cmd_branch
fi

# verify we have a checkpoint branch and exit if one wasn't found
if [ -z "$checkpoint_branch" ]; then
    echo "[ERROR]: no checkpoint/meta branch found. Either set KMETA or pass it via -b."
    exit 1
fi

git show-ref --quiet --verify -- "refs/heads/$checkpoint_branch"
if [ $? -eq 1 ]; then
    if [ -n "$verbose" ]; then
        echo "Checkpoint branch [$checkpoint_branch] does not exist, using default meta directory"
    fi
    meta_dir=$checkpoint_branch
else
    meta_dir=`get_meta_dir`
fi

echo $meta_dir

if [ -z "$files_to_checkpoint" ]; then
    dirs_to_checkpoint="$meta_dir/cfg/kernel-*cache $meta_dir/cfg/scratch \
                        $meta_dir/patches $meta_dir/scripts $meta_dir"
fi

if [ -n "$checkpointing" ]; then    
    if [ -n "$verbose" ]; then
	echo "[INFO]: Creating checkpoint on branch $checkpoint_branch"
    fi

    # if the branch doesn't already exist. Create it as an orphan.
    git show-ref --quiet --verify -- "refs/heads/$checkpoint_branch"
    if [ $? -eq 1 ]; then
        # create a meta-information branch
	git checkout --orphan $checkpoint_branch
	if [ $? != 0 ]; then
		echo "[ERROR]: orphan branch creation failed"
		exit -1
	fi
        # remove the unwanted files/directories
	git rm -rfq `ls -d .gitignore .mailmap * | grep -v $checkpoint_branch`
	if [ $? != 0 ]; then
		echo "[ERROR]: git rm -rfq failed"
		exit -1
	fi
    else
	git checkout $checkpoint_branch
	if [ $? != 0 ]; then
		echo "[ERROR]: checkpoint branch checkout failed"
		exit -1
	fi
    fi

    echo "kernel repository meta data base" >> README.txt
    git add -f README.txt
    if [ $? != 0 ]; then
	echo "[ERROR]: git add failed"
	exit -1
    fi
    git commit -s -m "meta: add README"
    if [ $? != 0 ]; then
	echo "[ERROR]: git commit README failed"
	exit -1
    fi
    
    # either we just created an orphan branch .. or it already
    # existed. Either way, iterate the directories that should be added to
    # the branch and add them.
    for d in $dirs_to_checkpoint; do
	count=`git ls-files -dmo $d | wc -l`
	if [ $count -eq 0 ]; then
	    # if there aren't any untracked files, then there's nothing to commit
	    continue
	fi
	git add -f $d
	if [ $? != 0 ]; then
		echo "[ERROR]: git add dirs failed"
		exit -1
	fi
	if [ -f "$d/00-README" ]; then
	    TXT=`mktemp`
	    echo "checkpoint dir: $d" > $TXT
	    echo >> $TXT
	    echo "What follows is the 00-README from dir \"$d\"." >> $TXT
	    echo >> $TXT
	    echo " ----------------------" >> $TXT
	    cat $d/00-README >> $TXT
	    echo " ----------------------" >> $TXT
	    git commit -q -s -F $TXT  &> /dev/null
	    if [ $? != 0 ]; then
		echo "[ERROR]: git commit 00-README failed"
		exit -1
	    fi
	    rm -f $TXT
	else
	    git commit -q -s -m "checkpoint dir: $d" &> /dev/null
	    if [ $? != 0 ]; then
		echo "[ERROR]: git commit checkpoint dir failed"
		exit -1
	    fi
	fi
    done

    if [ -z "$verbose" ]; then
	q="-q"
    fi

    # tag the branch so it can be found later
    git show-ref --quiet --verify -- "refs/tags/checkpoint-$checkpoint_branch"
    if [ $? -eq 1 ]; then
	git tag checkpoint-$checkpoint_branch
        if [ $? != 0 ]; then
		echo "[ERROR]: git tag checkpoint failed"
		exit -1
        fi
    fi

    # return to the current branch
    if [ "$checkpoint_branch" != "$current_branch" ]; then
	git checkout -q $current_branch
        if [ $? != 0 ]; then
		echo "[ERROR]: git checkout current failed"
		exit -1
        fi
    fi

else # restoring ...

    if [ -n "$verbose" ]; then
	echo "[INFO]: Restoring checkpoint from branch $checkpoint_branch"
    fi

    # check if '$meta_dir' is tracked or not. If it is untracked, we don't
    # have anything to do.
    meta_dir=`get_meta_dir`
    if [ -n "$meta_dir" ]; then
     	echo "[INFO]: checkpoint is already restored, nothing to do"
     	exit 0
    fi

    # We consider everything on the checkpoint branch to be part of the stored
    # state. If the branch was an orphan branch, the merge_base will be zero. In
    # that case, we just get all commits on the branch via git rev-list
    merge_base=`git merge-base $checkpoint_branch master`
    if [ -z "$merge_base" ]; then
	merge_base=`git rev-list $checkpoint_branch -- | tail -1`
    fi

    # save the old branch, and make the data untracked.
    git checkout -q -f -b $checkpoint_branch-temp $checkpoint_branch &> /dev/null
    if [ $? != 0 ]; then
	echo "[ERROR]: git checkout -q -b failed"
	exit -1
    fi
    git reset --mixed $merge_base &> /dev/null
    if [ $? != 0 ]; then
	echo "[ERROR]: git reset mixed failed"
	exit -1
    fi

    # At this point, we've reset the branch and the meta data is now
    # reset and can persist when we change the branch, but we need to
    # make a copy of them to *something* else, or git will complain about
    # them being clobbered when we switch away.

    if [ -d "$checkpoint_branch" ]; then
	checkpoint_dir=$checkpoint_branch
    else
	for f in `find -maxdepth 1 -type d -not -name .git -and -not -name . -printf '%f'`; do
	    if [ -d "$f" ]; then
	        # a directory is our meta dir
		checkpoint_dir=$f
	    fi
	done
    fi

    if [ ! -d ".$checkpoint_dir" ]; then
	mv $checkpoint_dir .$checkpoint_dir
    fi

    # delete our working branch, and return to the original one
    if [ "$checkpoint_branch" != "$current_branch" ]; then
	git checkout -f -q $current_branch
	if [ $? != 0 ]; then
	    echo "[ERROR]: git checkout -q failed"
	    exit -1
	fi
    else
	git checkout -f -q master
	if [ $? != 0 ]; then
	    echo "[ERROR]: git checkout -q failed"
	    exit -1
	fi
    fi

    git branch -D $checkpoint_branch-temp
    if [ $? != 0 ]; then
	echo "[ERROR]: git branch -D failed"
	exit -1
    fi

    # Double check the meta_dir, and write the results for following scripts
    meta_dir=`get_meta_dir`
fi