#!/bin/bash
# Finds commits with a review tag ("R=foo@example.com") and adds them as
# gerrit reviewer.
#
# Author: Peter Wu <lekensteyn@gmail.com>
# http://stackoverflow.com/q/24576855/427545
#
# Requirements: git, awk, ssh, bash

cd "$(git rev-parse --show-toplevel)"

user=
host=
port=29418
project=

# Load host from gitreview file if any
[ ! -f .gitreview ] ||
eval $(awk -F= '
$1 == "host" && $2 ~ /^[a-zA-Z0-9][a-zA-Z0-9.-]*$/ { print "host=" $2 }
$1 == "port" && $2 ~ /^[0-9]{1,5}$/ { print "port=" $2 }
$1 == "project" && $2 ~ /^[a-zA-Z0-9._][a-zA-Z0-9._-]*$/ { print "project=" $2 }
' .gitreview)

# Load settings from git config
eval $(git remote -v show -n |
awk -vorighost=$host '/fetch\)$/ && $2 ~ /^ssh:/ {
    split($2, url, /[/:@]+/);

    # Apply settings on first result, or if the host matches
    if (!got_one || orighost == url[3]) {
        if (url[2] ~ /^[a-zA-Z0-9][a-zA-Z0-9.-]*$/)
            print "user=" url[2];
        if (url[3] ~ /^[a-zA-Z0-9][a-zA-Z0-9.-]*$/)
            print "host=" url[3];
        if (url[4] ~ /^[0-9]{1,5}$/)
            print "port=" url[4];
        got_one = 1;
    }
}')

find_reviewers() {
    local commit=$1

    git show --no-patch --format=%b "$commit" |
    awk -F= '/^R=[a-zA-Z0-9@._+-]+$/ { print $2 }'
}

set_reviewer() {
    local cmd reviewer
    local commit=$1 # Commit or Change-Id
    shift # Remaining arguments: reviewers

    # https://review.openstack.org/Documentation/cmd-set-reviewers.html
    cmd='gerrit set-reviewers'
    [ -z "$project" ] || cmd="$cmd --project $project"
    for reviewer; do
        cmd="$cmd -a $reviewer"
    done
    cmd="$cmd -- $commit"

    echo "$cmd" >&2
    ssh -p $port "$user@$host" "$cmd"
}

check_commits() {
    local revlist=$1 commits count=0 retval=0

    # One is not going to push that many commits/reviews at a time...
    commits="$(git rev-list --reverse --max-count=100 $revlist --)" || return 1

    if [ -z "$commits" ]; then
        echo "No commits found" >&2
        return 1
    fi

    for commit in $commits; do
        reviewers=$(find_reviewers $commit)
        if [ -n "$reviewers" ]; then
            echo "Adding reviewers for $commit..." >&2
            if ! set_reviewer $commit $reviewers; then
                echo >&2
                echo "Run 'git review' if you get a 'no such change' error" >&2
                retval=1
                break
            fi
            ((count++))
        fi
    done

    printf 'Touched %d commits' $count >&2
    if [ $retval -eq 0 ]; then
        echo . >&2
    else
        echo ", but stopped due to an error" >&2
    fi

    return $retval
}

if [ -z "$user" ] || [ -z "$host" ]; then
    echo "Warning: gerrit is not configured" >&2
    exit 1
fi

case ${0##*/} in
post-review)
    # TODO
    # maybe read https://review.openstack.org/Documentation/cmd-query.html
    # if pre:
    #   create temp file with possibly unprocessed commits
    echo "$0: Not implemented" >&2
    ;;
pre-review)
    # TODO
    # elif post:
    #   read temp file
    #   for each reviewer in temp file:
    #       ssh user@host -p port 'gerrit command to set reviewer'
    echo "$0: Not implemented" >&2
    ;;
*)
    if [[ $1 == *..* ]]; then
        check_commits "$1"
    else
        echo "Usage: $0 <revlist>" >&2
        echo "To review changes on this branch since master: $0 master.." >&2
        exit 1
    fi
    ;;
esac