#!/bin/sh
#
# Copyright (c) 2017 Aaron LI <aly@aaronly.me>
# MIT License
#
# Sync public repositories to GitHub.
#
# 2017-06-25
#

. ${HOME}/vars.conf

# Return 0 if the GitHub repository exists
has_github_repo() {
    local repo url
    repo=$(basename $1)
    repo="${repo%.git}"
    url="${GITHUB_API}/repos/${GITHUB_USER}/${repo}"
    echo "Check existence on GitHub: ${url}"
    curl -s ${url} | grep -q '"owner"'
}


# Add the "github" remote if not exists
add_remote_github() {
    local gitdir_ repo url ret
    gitdir_="$1"
    url=$(git --git-dir="${gitdir_}" remote get-url github 2>&1)
    ret=$?
    if [ ${ret} -eq 0 ]; then
        # Already has the "github" remote
        echo "Remote 'github': ${url}"
    else
        repo=$(basename ${gitdir_})
        url="${GITHUB_URL}:${GITHUB_USER}/${repo}"
        git --git-dir="${gitdir_}" remote add github ${url}
        echo "Added remote 'github': ${url}"
        git --git-dir="${gitdir_}" remote update github
    fi
}


# Check whether the repository needs push to remote "github";
# Return 0 if needs push.
#
# Credit:
# * Check if pull needed in Git
#   https://stackoverflow.com/a/3278427/4856091
# * List Git commits not pushed to the origin yet
#   https://stackoverflow.com/a/3080554/4856091
#
need_push_github() {
    local gitdir_ unpushed
    gitdir_="$1"
    unpushed=$(git --git-dir="${gitdir_}" \
                   log --oneline github/master..master | wc -l)
    if [ ${unpushed} -eq 0 ]; then
        echo "Already up-to-date" && false
    else
        echo "${unpushed} commits need push" && true
    fi
}


if [ $# -eq 0 ]; then
    cat <<_EOF_
usage:
    sync-github <repo.git> ...
    sync-github @<repo_dir>

e.g.,
    sync-github @${PUBLIC}
_EOF_
    exit 1
fi


if [ "$(echo $1 | cut -c1)" = "@" ]; then
    REPO_DIR="${1#@}"
    REPOS=$(ls -d ${REPO_DIR}/*.git)
else
    REPOS="$@"
fi

echo "=== Selected Repositories ==="
for repo in ${REPOS}; do
    repo2="${repo%.[gG][iI][tT]}.git"
    echo "* ${repo2}"
done

for repo in ${REPOS}; do
    repo2="${repo%.[gG][iI][tT]}.git"
    echo "=== Sync Repository: ${repo2} ==="
    if ! has_github_repo ${repo2}; then
        echo "WARNING: no such repo on GitHub: ${repo2}"
        continue
    fi
    add_remote_github ${repo2}
    if need_push_github ${repo2}; then
        echo "Push commits to GitHub ..."
        git --git-dir="${repo2}" push --mirror github
    fi
done