#!/bin/bash

set -e

platform=$(uname)
if [ "$platform" == 'Darwin' ]
then
    sed=$(which gsed || errcho "install gnu-sed")
else
    sed=$(which sed)
fi

semver_regex="^(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(\-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?(\+[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$"

usage="\
Usage:
  $0
  $0 show
  $0 major

Commands:
  show    fetch and show current versions.
  major   bump the major level of current version.
  minor   bump the minor level of current version.
  patch   bump the patch level of current version."

function errcho {
    >&2 echo -e "error: $*"
    exit 1
}

function update {
    git fetch --tags
}

function show {
    echo "Current git tag: $current_tag"
    echo "Current meta version: $current_version"
}

function validate {
    local version="$1"
    if [[ "$version" =~ $semver_regex ]]
    then
        apply "$version"
    else
        errcho "version $version does not follow semver standard"
    fi
}

function bump {
    local level="$1"
    IFS=$'.'
    set -- $current_version
    local major=$1
    local minor=$2
    local patch=$3
    case $level in
        major) ((major++));;
        minor) ((minor++));;
        patch) ((patch++));;
    esac
    validate "$major.$minor.$patch"
}

function apply {
    local new_version="$1"
    $sed -i "s/$current_version/$new_version/" "metadata.rb"
    (git add metadata.rb && git commit -m"bump to $new_version") || true
    git tag "$new_version"
    git push origin
    git push origin --tags
}

if [ ! -f metadata.rb ]
then
    errcho "metadata.rb file missing"
fi

current_version=$(grep -E '^version' metadata.rb | cut -d"'" -f2 || errcho "a cookbook version was not found")
current_tag=$(update | git describe --abbrev=0 --tags || echo 'none found')

if [ -z "$1" ]
# there are no args
then
    show
    read -r -p "enter a new semver version: " answer
    validate "$answer"
# there are args
else
    # first arg was semver
    if [[ "$1" =~ $semver_regex ]]
    then
        apply "$1"
    else
        # first arg is either a known command or throw usage
        case "$1" in
            show) show;;
            major|minor|patch) bump "$1";;
            *) echo "$usage"; exit 1;;
        esac
    fi
fi