#!/bin/bash
set -e

function select_branch() {
    echo "Not merged branches on origin:"
    branches=`git branch --list -r --no-merged`
    IFS=$'\n' read -d '' -r -a branches_arr <<< "$branches" || true # dunno why, IFS raises error code
    if [ ${#branches_arr[@]} -eq 0 ]; then
        echo "\e[93mNo unmerged remote branches found\e[0m"
        exit
    fi
    for i in "${!branches_arr[@]}"; do 
        branch=${branches_arr[$i]}
        branch="$(echo -e "${branch}" | sed -e 's/^[[:space:]]*//')"
        branch=${branch#origin/}
        branches_arr[$i]=$branch
        echo "$((i + 1)). $branch"
    done
    selected_index=-1
    while [ $selected_index -lt 0 ] || [ $selected_index -gt ${#branches_arr[@]} ]; do
        echo -n "Enter number of branch you want to merge> "
        read selected_index
        if [ $selected_index -lt 0 ]; then
            echo "Negative number? Seriously?"
        elif [ $selected_index -gt ${#branches_arr[@]} ]; then
            echo "Number greater than last branch's index? Why?"
        else
            selected_index=$((selected_index - 1))
        fi
    done
    selected_branch=${branches_arr[$selected_index]}
    eval "$1=$selected_branch"
}

merge_target_branch=master

if [ ! -z "`git status --porcelain`" ]; then
    echo -e "\e[93mYou have uncommited changes in your repository local copy. Commit or stash them before running this script\e[0m"
    exit
fi

cur_branch=`git rev-parse --abbrev-ref HEAD`
if [ "$cur_branch" != "$merge_target_branch" ]; then
    git checkout "$merge_target_branch" --quiet
fi

git pull origin "$merge_target_branch" --ff-only --quiet

git fetch --quiet

select_branch merge_source_branch
merge_source_branch_head_sha=`git show-ref $merge_source_branch -s`
merge_source_branch_author=`git show --quiet --format="%aN <%aE>" "$merge_source_branch_head_sha"`

# echo "Source branch: $merge_source_branch"
# echo "Source branch HEAD: $merge_source_branch_head_sha"
# echo "Source branch author: $merge_source_branch_author"

git merge --quiet --squash origin/$merge_source_branch
git commit --author="$merge_source_branch_author" --quiet

git push origin $merge_target_branch --quiet

if [ $cur_branch != "$merge_target_branch" ]; then
    git checkout "$cur_branch" --quiet
fi

git push origin :$merge_source_branch --quiet

echo -e "\e[92mDone\e[0m"