#!/bin/bash

# Copyright (C) 2009 Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# To set user mappings, use this command:
#   git config gnt-review.johndoe 'John Doe <johndoe@example.com>'

# To disable strict mode (enabled by default):
#   git config gnt-review.strict false

# To enable strict mode:
#   git config gnt-review.strict true

set -e

# Get absolute path to myself
me_plain="$0"
me=$(readlink -f "$me_plain")

add_reviewed_by() {
  local msgfile="$1"

  grep -q '^Reviewed-by: ' "$msgfile" && return

  perl -i -e '
  my $reviewer = $ENV{"REVIEWER"};
  defined($reviewer) or $reviewer = "";
  my $sob = 0;
  while (<>) {
    if ($sob == 0 and m/^Signed-off-by:/) {
      $sob = 1;

    } elsif ($sob == 1 and not m/^Signed-off-by:/) {
      print "Reviewed-by: $reviewer\n";
      $sob = -1;
    }

    print;
  }

  if ($sob == 1) {
    print "Reviewed-by: $reviewer\n";
  }
  ' "$msgfile"
}

replace_users() {
  local msgfile="$1"

  if perl -i -e '
  use strict;
  use warnings;

  my $error = 0;
  my $strict;

  sub map_username {
    my ($name) = @_;

    return $name unless $name;

    my @cmd = ("git", "config", "--get", "gnt-review.$name");

    open(my $fh, "-|", @cmd) or die "Command \"@cmd\" failed: $!";
    my $output = do { local $/ = undef; <$fh> };
    close($fh);

    if ($? == 0) {
      chomp $output;
      $output =~ s/\s+/ /;
      return $output;
    }

    unless (defined $strict) {
      @cmd = ("git", "config", "--get", "--bool", "gnt-review.strict");

      open($fh, "-|", @cmd) or die "Command \"@cmd\" failed: $!";
      $output = do { local $/ = undef; <$fh> };
      close($fh);

      $strict = ($? != 0 or not $output or $output !~ m/^false$/);
    }

    if ($strict and $name !~ m/^.+<.+\@.+>$/) {
      $error = 1;
    }

    return $name;
  }

  while (<>) {
    if (m/^Reviewed-by:(.*)$/) {
      my @names = grep {
        # Ignore empty entries
        !/^$/
      } map {
        # Normalize whitespace
        $_ =~ s/(^\s+|\s+$)//g;
        $_ =~ s/\s+/ /g;

        # Map names
        $_ = map_username($_);

        $_;
      } split(m/,/, $1);

      # Get unique names
      my %saw;
      @names = grep(!$saw{$_}++, @names);
      undef %saw;

      foreach (sort @names) {
        print "Reviewed-by: $_\n";
      }
    } else {
      print;
    }
  }

  exit($error? 33 : 0);
  ' "$msgfile"
  then
    :
  else
    [[ "$?" == 33 ]] && return 1
    exit 1
  fi

  if ! grep -q '^Reviewed-by: ' "$msgfile"
  then
    echo 'Missing Reviewed-by: line' >&2
    sleep 1
    return 1
  fi

  return 0
}

run_editor() {
  local filename="$1"
  local editor=${EDITOR:-vi}
  local args

  case "$(basename "$editor")" in
    vi* | *vim)
      # Start edit mode at Reviewed-by: line
      args='+/^Reviewed-by: +nohlsearch +startinsert!'
    ;;
    *)
      args=
    ;;
  esac

  $editor $args "$filename"
}

commit_editor() {
  local msgfile="$1"

  local tmpf=$(mktemp)
  trap "rm -f $tmpf" EXIT

  cp "$msgfile" "$tmpf"

  while :
  do
    add_reviewed_by "$tmpf"

    run_editor "$tmpf"

    replace_users "$tmpf" && break
  done

  cp "$tmpf" "$msgfile"
}

copy_commit() {
  local rev="$1" target_branch="$2"

  echo "Copying commit $rev ..."

  git cherry-pick -n "$rev"
  GIT_EDITOR="$me --commit-editor \"\$@\"" git commit -c "$rev" -s
}

usage() {
  echo "Usage: $me_plain [from..to] <target-branch>" >&2
  echo "  If not passed from..to defaults to target-branch..HEAD" >&2
  exit 1
}

main() {
  local range target_branch

  case "$#" in
  1)
    target_branch="$1"
    range="$target_branch..$(git rev-parse HEAD)"
  ;;
  2)
    range="$1"
    target_branch="$2"
    if [[ "$range" != *..* ]]; then
      usage
    fi
  ;;
  *)
    usage
  ;;
  esac

  git checkout "$target_branch"
  local old_head=$(git rev-parse HEAD)

  for rev in $(git rev-list --reverse "$range")
  do
    copy_commit "$rev"
  done

  git log "$old_head..$target_branch"
}

if [[ "$1" == --commit-editor ]]
then
  shift
  commit_editor "$@"
else
  main "$@"
fi