#!/bin/bash
#
# git-update
# Pull down latest from git remote and remove dead branches
#
# To create an alias to `git update`, put this on your path, then:
# git config --global alias.update '!git-update'
#
# Copyright (c) 2016 Leftclick.com.au
# License: MIT
#

# Defaults
branch=master
upstream=upstream
delayPeriod=
displayUsage=false
errorMessage=

# Parse options
while getopts d:h param; do
    case $param in
        d)
            delayPeriod="$OPTARG"
        ;;
        h)
            displayUsage=true
        ;;
        *)
            errorMessage="Unknown argument, please check usage instructions"
            displayUsage=true
        ;;
    esac
done
shift $(expr $OPTIND - 1)

# Check for too many arguments
if [ $# -gt 2 ]; then
    errorMessage="Too many arguments, please check usage instructions"
    displayUsage=true
fi

# Display usage if requested or arguments are invalid
if [ "${displayUsage}" = true ]; then
    if [ "${errorMessage}" != "" ]; then
        echo "${errorMessage}" 1>&2
    fi
    echo "Usage: $0 [-d <delay>] [<remote>] [<branch>]"
    echo "Where:"
    echo "  <delay> is the number of seconds delay between steps (default 1)"
    echo "  <branch> is the name of the branch to switch to and pull from (default 'master')"
    echo "  <remote> is the name of the remote to pull from (default 'upstream')"
    if [ "${errorMessage}" != "" ]; then
        exit 1
    else
        exit 0
    fi
fi

# Wait the `delayPeriod` or until user presses ENTER, if a `delayPeriod` is set
function delay {
    if [ -n "${delayPeriod}" ]; then
        read -t ${delayPeriod} -p "Waiting for ${delayPeriod}s; press ENTER to skip waiting, or CTRL+C to cancel"
    fi
    echo
}

# Main processing sequence
echo "Switching to ${branch}"
git checkout "${branch}"
delay

echo "Fetching data"
fetchOutput=$( { git fetch -p; } 2>&1 )
echo "${fetchOutput}"
delay

echo "Pulling latest from upstream"
git pull "${upstream}" "${branch}"
delay

echo "Pushing to origin"
git push
delay

echo "Removing dead branches"
while read -r line; do
    if [[ "${line}" == *"[deleted]"* ]]; then
        deadBranch=$( echo "${line}" | sed "s/^.*\[deleted\].*-> \w*\///" )
        echo "Removing branch: ${deadBranch}"
        git branch -d "${deadBranch}"
    fi
done <<< "${fetchOutput}"

echo "Done, displaying branches and status"
git branch -v
git status