#!/bin/bash
#
# Copyright (c) 2007 Jean-Francois Richard <jean-francois@richard.name>
#           (c) 2008 Mauricio Fernandez <mfp@acm.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.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see
# <http://www.gnu.org/licenses/>.

version="0.3.0"

if ! which git &>/dev/null; then
    echo "Please Git" >&2
    echo "See http://git.or.cz for more information about Git" >&2
    exit 1
fi

# Autotools defines
MANDIR="/usr/local/share/man"

SCRIPT_NAME=$(basename $0)
ORIG_DIR="$( pwd )"
# Remember that all actions here are to be made in $HOME dir!
cd ~

# We don't want users complaining.  by default, top permissions
# "security"
umask 077

# We don't check for just '.git', as the user might have
# mounted/linked .git from somewhere else.  Failing on just '-e
# .git' would make it impossible to have the first commit save its
# data to a remote mount.  (Since .git has to exist, as a mountpoint)
function __has_initialized(){
    test -e .git/objects;
    return $?
}

function __abort_on_initialized() {
    if __has_initialized; then
	echo "You already have git data in your home directory." >&2
	echo "Please use '$SCRIPT_NAME rm-all' if you wish to *delete* it." >&2
	exit 1
    fi
}

function __abort_on_not_initialized() {
    if ! __has_initialized; then
	echo "You probably did not initialize your home history repository" >&2
	echo "Please use  '$SCRIPT_NAME init' to initialize it" >&2
	exit 1
    fi
    # further tests
    source git-sh-setup
    require_work_tree
}

function __abort_on_no_gpg() {
    if ! which gpg >/dev/null; then
	echo "You need to install GPG to use this feature" >&2
	exit 1
    fi
}

function __handle_git_repositories() {
    __abort_on_not_initialized
    cd_to_toplevel
    echo "Managing submodules." >&2
    rm -f .gitmodules
    local base=.git/git-repositories
    mkdir -p $base
    find-git-repos -i -z | while read -d $'\0' rep; do
	echo "  submodule $rep" >&2
	rsync -a -F --relative --delete-excluded --delete-after \
	    "$rep" "$base"
	printf '[submodule "%s"]\n\tpath = %s\n\turl= %s\n' \
	    "$rep" "$rep" "$base/$rep/.git" >> .gitmodules
    done
    touch .gitmodules
    git-add -f .gitmodules
    git-submodule init
}

function init() {
    __abort_on_initialized

    # I know it's the default... but let's be explicit!
    git-init --shared=umask
    chmod -R u+rwX,go-rwx .git

    # Add a gitweb description
    echo "git-home-history of $HOME on $(hostname)" > .git/description

    # Make sure there is a 'name' field in config... some git scripts
    # complain if not
    if test "$(getent passwd 2>&1 | grep $USER | cut -d: -f5)" = ""; then
	  git config user.name "$USER"
    fi

    # Check for xdg-user-dirs to provide sane defaults in .gitignore
    # http://www.freedesktop.org/wiki/Software/xdg-user-dirs
    test -f ${XDG_CONFIG_HOME:-~/.config}/user-dirs.dirs && source ${XDG_CONFIG_HOME:-~/.config}/user-dirs.dirs
    XDG_DOWNLOAD_DIR=$( echo ${XDG_DOWNLOAD_DIR#${HOME}} | sed 's:^/*::' )
    XDG_VIDEOS_DIR=$( echo ${XDG_VIDEOS_DIR#${HOME}} | sed 's:^/*::' )
    XDG_MUSIC_DIR=$( echo ${XDG_MUSIC_DIR#${HOME}} | sed 's:^/*::' )

    cat << EOF > .git/hooks/pre-commit
#!/bin/sh

ometastore -x -s -i --sort
git add -f .ometastore
EOF

    cat << EOF > .git/hooks/post-checkout
#!/bin/sh

ometastore -v -x -a -i
EOF

    test -e .gitignore || cat << EOF > .gitignore
#
# Here are some examples of what you might want to ignore
# in your git-home-history.  Feel free to modify.
#
# Example rules start with '##'.
# You can remove the '##' to set the rule.
#
# The rules are read from top to bottom, so a rule can
# "cancel" out a previous one.  Be careful.
#
# For more information on the syntax used in this file,
# see "man gitignore" in a terminal or visit
# http://www.kernel.org/pub/software/scm/git/docs/gitignore.html

##/${XDG_DOWNLOAD_DIR:-Download}
##/${XDG_VIDEOS_DIR:-Videos}
##/${XDG_MUSIC_DIR:-Music}

# Notice the '!' below.  This tells git to _not_ ignore a file or
# directory, in this case, we do not want to ignore a particular
# directory under Music/, which is ignored according to the rule
# above.

##!/${XDG_MUSIC_DIR:-Music}/Our_Daughter--Flute

# You probably want to ignore all the "dot" files in your home
# directory, since they mostly contain local application state data.

##/.*
# but... some dot files you probably do *not* want ignored are
# listed here:
##!/.bash*
##!/.tcsh*
##!/.zsh*
##!/.emacs
##!/.gnupg
##!/.mail
##!/.maildir
##!/.Maildir
##!/.mail-aliases
##!/.muttrc
##!/.ssh
##!/.vimrc

# We do not want to track the tracking of other files:
#.svn
#CVS
# Please note that all files in a Git project are ignored
# e.g. linux-2.6/ will be entirely ignored if linux-2.6/.git exists.
# Thus it is not necessary to add ".git" here.

# Some editors use some special backup file formats.  Ignore them:
##.#*
##*~

EOF

    git-add -f .gitignore
    git-commit -q -a -m"Initialized by $SCRIPT_NAME"
    chmod u+x .git/hooks/pre-commit
    chmod u+x .git/hooks/post-checkout
    echo
    echo "You might be interested in tweaking the ~/.gitignore file"
    echo
    echo "Please run '$SCRIPT_NAME commit' to save a first state in your history"
}

function rm_all() {
    if __has_initialized; then
	echo "Removing all git-home-history data, this may take some time "
        # We don't remove '.git', as the user might have
        # mounted/linked .git from somewhere else.  Removing the link
        # would silently break what the user was expecting; removing a
        # device mountpoint will fail anyway.
	rm -rf .git/* 2>/dev/null
	#rm -rf .gitignore 2>/dev/null
    else
	echo "Nothing to do"
    fi
}


function commit() {
    __abort_on_not_initialized
    local what=$@
    local modifier=

    echo "Committing to repository, this may take a long time" >&2
    if git-ls-files --modified --others --exclude-standard | egrep -q '(^|/).gitignore$'; then
	echo "Some .gitignore added or modified, determining newly ignored files." >&2
	# I don't like myself for using such a sloppy way of
	# removing previously-tracked newly-ignored files...
	# :(  help me! ahhhhrrrggg
	# seems like the only way to stop tracking newly-ignored files
	#git-rm --cached -r -f . >/dev/null

	# better way, using ometastore
        ometastore -d -i -z | \
	xargs -0 git rm --cached -r -f --ignore-unmatch -- 2>/dev/null
    fi
    echo "Adding new and modified files." >&2
    git-add -v . \
	|| die "Could not complete addition of files to history store!"
    __handle_git_repositories
    test -n "$what" || modifier="-a"
    echo "Committing." >&2
    git-commit $modifier -m"Committed on $( date +"%a, %d %b %Y %H:%M:%S %z" )" -- $@
    echo "Optimizing and compacting repository (might take a while)." >&2
    git-gc --auto || git-gc # the --auto is on newer versions
}


function rm_older_than() {
    __abort_on_not_initialized
    local time_spec=$@

    if ! which git-filter-branch &>/dev/null; then
	echo "Please install a recent version of Git" >&2
	echo "See http://git.or.cz for more information about Git" >&2
	exit 1
    fi

    if test $(git-rev-parse "HEAD@{$time_spec}") = "$(git-rev-parse HEAD)"; then
	local TMOUT=20
	echo "You are about to remove *all* commits made before the very last one you made"
	echo "Press enter or wait 20 seconds to confirm.  Abort with CRTL-C."
	read
    fi

    # Something like that
    git-filter-branch --parent-filter \
	'test $(git-rev-parse "HEAD@{$time_spec}") = "$GIT_COMMIT" || cat ' \
	HEAD
    if test "$?" != "0"; then
	die "Please make sure you did '$SCRIPT_NAME commit' before removing old files."
    fi

    # See git mailing list
    # "Trying to use git-filter-branch to compress history by removing
    # large, obsolete binary files"

    git reset --soft # was '--hard' on the post...
    rm -rf .git/refs/original/
    #vi .git/packed-refs # Use vi to remove the line referring to
    # refs/original...  No need since we have linear, no tags, nothing
    # special
    git-reflog expire --all --expire-unreachable=0

    echo "Committing the removal action"

    # Make sure we are able to tell in a commit that on this
    # date, a cleanup was made
    local removal_date=$( date +"%a, %d %b %Y %H:%M:%S %z" )
    local witness_file=.git-home-history-last-removal
    local msg="Removed older than '$time_spec' on $removal_date"
    echo "$msg" > ${witness_file}
    git add $witness_file
    git commit -m"$msg" $witness_file

    # Finally make sure everything is ok, and remove old stuff
    git-gc --prune
}


function show() {
    __abort_on_not_initialized

    local file_to_restore=$1
    shift
    shift # 'as'
    shift # 'of'
    local time_spec=$@

    echo "Showing: $HOME/$file_to_restore" >&2
    GIT_PAGER=cat git-show "HEAD@{'$time_spec'}:$file_to_restore"
}

function archive_to() {
    __abort_on_not_initialized
    __abort_on_no_gpg

    local output="$1"

    if test "$output" != "-"; then
	output="$ORIG_DIR/${1%.git.tar.gpg}.git.tar.gpg"
    fi

    echo "Saving archive to '$output'" >&2
    echo "This may take a long time" >&2
    tar -cpf - .git | gpg -c --output "$output"
}


function extract_archive_to() {
    __abort_on_no_gpg
    local archive="${1%.git}.git"

    # Use the path from where the command was run: ORIG_DIR
    pushd "$ORIG_DIR" >/dev/null

    if test -e "$archive"; then
	echo "$(basename $archive) already exists, please move it away" >&2
	exit 1
    fi

    echo "Extracting archive, this may take a long time" >&2
    mkdir "$archive" >&2
    # We only specify .git to unpack.  Else a user could well unpack
    # something else and trash his files
    gpg -d - | tar --strip-components 1 -C"$archive" -xpf - .git
    echo
    echo "You can check what files are inside the newly unpacked directory with"
    echo "GIT_DIR=\"$archive\" gitk"
    echo "GIT_DIR=\"$archive\" git-home-history ls-stored-files"

    popd >/dev/null
}

function ls_stored_files() {
    __abort_on_not_initialized

    if test "$#" -gt "2"; then
	shift # as
	shift # of
	local time_spec="$@"
	git-ls-tree -r --name-only "HEAD@{$time_spec}"
    else
	git-ls-tree -r --name-only HEAD
    fi
}

function eat() {
    __abort_on_not_initialized

    git-add -v -- $@ || die "Could not add '$@' to the history store"
    commit $@
    git-rm -r -f -- $@ || die "Problem removing '$@'"
    rm -rf -- $@ # some empty dirs may remain. clean'em up
    commit $@
}

case "$1" in
    private--init-and-commit)
	if ! __has_initialized ; then
	    init
	fi
	commit
	;;
    init)
	init
	;;
    archive-to)
	# output can be stdout, using '-' or a file
	shift
	archive_to $@
	;;
    extract-archive-to)
	# output can only be a file
	shift
	if test "$#" -gt "1"; then
	    echo "Please specify one output archive file" >&2
	    echo "e.g. cat archive | $SCRIPT_NAME extract-archive-to machineA.git" >&2
	    exit 1
	fi
	extract_archive_to "$1"
	;;
    show)
	shift
	if test "$#" -lt "4"; then
	    echo "Please specify what to show from the history store, as of when" >&2
	    echo "e.g. $SCRIPT_NAME show 'myfile.txt' as of 2 days ago" >&2
	    exit 1
	fi
	show $@
	;;
    commit)
	commit
	;;
    eat)
	if test "$ORIG_DIR" != "$HOME"; then
	    echo "Please run this from your home directory" >&2
	    echo "cd $HOME" >&2
	    exit 1
	fi
	shift
	if test "$#" -lt "1"; then
	    echo "Please specify what file or directory to eat" >&2
	    echo "e.g. $SCRIPT_NAME eat 'myfile.txt'" >&2
	    exit 1
	fi
	eat $@
	;;
    rm-older-than)
	shift
	if test "$#" = "0"; then
	    echo "Please add a time specification" >&2
	    echo "e.g. '1 year ago' or '1979-02-26 18:30:00'" >&2
	    exit 1
	fi
	rm_older_than $@
	;;
    rm-all)
	rm_all
	;;
    ls-changed-files)
        echo "These files have been modified:" >&2
        git-ls-files --exclude-standard --modified
	echo "Use '$SCRIPT_NAME commit' to store them" >&2
        ;;
    ls-new-files)
	echo "These files are not yet stored:" >&2
	git-ls-files --exclude-standard --others
	echo "Use '$SCRIPT_NAME commit' to store them" >&2
	;;
    ls-ignored-files)
	echo "These files are ignored:" >&2
	git-ls-files --exclude-standard --ignored --others --directory
	;;
    ls-newly-ignored-files)
        echo "These files have been ignored since the last commit:" >&2
	if git-ls-files --modified --others --exclude-standard | egrep -q '(^|/).gitignore$'; then
	    ometastore -d -i | sort
	fi
	;;
    ls-stored-files)
	shift
	ls_stored_files $@
	;;
    --help|-h|help)
	manfile="${SCRIPT_NAME}.1"

	found=
	for t in "$MANDIR/man1/$manfile" "$ORIG_DIR/gibak.1"; do
	    if test -e "$t"; then
		man $t
		found=1
		break
	    fi
	done
	if test -z "$found"; then
	    man gibak
	    if test "$?" != "0"; then
		echo "Could not find manpage" >&2
	    fi
	fi
	;;
    --version)
	echo "gibak version $version"
	exit 0
	;;
    *)
	echo "usage: $SCRIPT_NAME <action>"
	echo
	echo "<action> can be:"
	echo "    help"
	echo "    init"
	echo "    commit"
	echo "    eat <file_or_dir>"
	echo "    show <file> as of <time_spec>"
	echo "    ls-changed-files"
	echo "    ls-new-files"
	echo "    ls-ignored-files"
	echo "    ls-newly-ignored-files"
	echo "    ls-stored-files [as of <time_spec>]"
	echo "    archive-to <file>"
	echo "    extract-archive-to <dir>"
	echo "    rm-all"
	echo "    rm-older-than <time_spec>"
	echo 
	echo "<time_spec> examples:"
	echo "    5 days ago"
	echo "    2 days 2 hours 3 seconds ago"
	echo "    1979-02-26 18:30:00"
	echo ""
	echo "see 'man gibak' for more information"
	exit 1
	;;
esac
exit 0
# vim: set noexpandtab sw=4: