#!/usr/bin/env perl

# Copyright (C) 2019-2020 Sean Whitton
#
# 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 3 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 <https://www.gnu.org/licenses/>.

# EXAMPLE
#
#   % git log --format='format:%H' \
#       --since='1 day ago' --grep='delete junk' --grep='delete more junk' \
#       | xargs annex-drop-files-deleted-by-commit

use 5.028;
use strict;
use warnings;
use lib "$ENV{HOME}/src/dotfiles/perl5";

use File::Path qw(rmtree);
use File::Temp qw(tempdir);
use Git::Wrapper;
use Try::Tiny;
use Local::ScriptStatus;
use Local::Interactive qw(prompt_yn);
use File::chdir;
use Cwd;

my $git = Git::Wrapper->new(getcwd);
#<<<
try {
    $git->rev_parse({ git_dir => 1 });
} catch {
    die "pwd doesn't look like a git repository ..\n";
};
#>>>

my $temp = tempdir CLEANUP => 1;
chmod 0700, $temp;
$git->worktree("add", { force => 1, no_checkout => 1, detach => 1 }, $temp);
my $worktree = Git::Wrapper->new($temp);
for (@ARGV) {
    local $CWD = $temp;

    my ($commit) = $git->rev_parse($_);
    my @deleted_files = $git->RUN(
        qw(-c core.quotePath=false diff),
        { name_only => 1, diff_filter => 'D' },
        "$commit~1..$commit"
    );
    $worktree->checkout("$commit~1");

    # We ought to be able to just `ga drop` the files here, but the
    # symlinks might be broken if the repo is bare and has
    # .git/annex/objects organised differently.  And 'lookupkey'
    # doesn't work in bare repos either.  So, extract the key from the
    # symlink
    my @deleted_keys;
    for (@deleted_files) {
        readlink =~ /SHA256E-s[0-9]+--[0-9a-f]+\.[a-zA-Z0-9]+$/;
        $& or die "couldn't determine key of $_";
        push @deleted_keys, $&;
    }

    # using dropkey is like passing --force to `git annex drop`
    say_spaced_bullet "Will drop with --force:";
    # for (my $i = 0 ; $i < @deleted_files ; $i++) {
    #     say "$deleted_files[$i]  $deleted_keys[$i]";
    # }
    say for @deleted_files;
    say '';

    if (prompt_yn "Go ahead with this?") {
        say for $git->annex(qw|dropkey --force|, @deleted_keys);
    }
}
# we can't use `git worktree remove` because the way git-annex
# worktree support works breaks that command: git-annex replaces the
# .git worktree file with a symlink
rmtree $temp;
$git->worktree("prune");