feat(#146): provides installation script

docs/installation.adoc

@@ -1,14 +1,33 @@
 == Installation
 
+=== Don't make me think
+
+Ok, just execute following snippet and you are all set:
+
+[[installing]]
+`curl -sS https://git.io/v5jMS | bash` copyToClipboard:installing[]
+
+You can also add these flags:
+
+  * `-l|--latest` latest published artifact in Maven Central
+  * `-r|--release` latest release (that's the default)
+  * `-v|--version=` - specific version to install
+
+For example:
+
+`curl -sS https://git.io/v5jMS | bash -- --latest`
+
+This script will automatically do what we described below. If you are curious keep on reading, but you may skip it too.
+
 === Maven Extension
 
-*Smart Testing* is a Maven extension, so needs to be installed as is.
+*Smart Testing* is a Maven extension, so depending on the version of Maven you have to follow slightly different approach of installing it.
 
-==== Maven >= 3.1.X
+==== Maven above 3.1.X
 
-Get Smart Testing _shaded_ copy from https://bintray.com/arquillian/Arquillian/smart-testing[Bintray] and copy it to `M2_HOME/lib/ext`
+Get Smart Testing Extension _shaded jar_ from http://central.maven.org/maven2/org/arquillian/smart/testing/maven-lifecycle-extension/[Maven Central] and copy it to `M2_HOME/lib/ext`.
 
-==== Maven >= 3.3.X
+==== Maven above 3.3.X
 
 You can still use the process described at <<Maven >= 3.1.X>> or use the new _core extension configuration mechanism_ by
 creating folder called `.mvn` in the root of your project and create inside it an `extensions.xml` file

install.sh

@@ -0,0 +1,137 @@
+#!/usr/bin/env bash
+
+MAVEN_METADATA=$(curl -sL http://central.maven.org/maven2/org/arquillian/smart/testing/smart-testing-parent/maven-metadata.xml)
+LATEST=$(echo ${MAVEN_METADATA} | grep -oPm1 "(?<=<latest>)[^<]+")
+RELEASE=$(echo ${MAVEN_METADATA} | grep -oPm1 "(?<=<release>)[^<]+")
+
+VERSION=${RELEASE}
+INSTALL_SPECIFIC_VERSION="0"
+
+while test $# -gt 0; do
+       case "$1" in
+            -h|--help)
+                echo "Installs Arquillian Smart Testing Extension"
+                echo "options:"
+                echo "-l, --latest                   installs latest version of the extension"
+                echo "-r, --release                  installs latest released version of the extension"
+                echo "-v, --version=VERSION          installs defined version (doesn't check if exists!)"
+                exit 0
+                ;;
+            -l|--latest)
+                shift
+                VERSION=${LATEST}
+                shift
+                ;;
+            -r|--release)
+                shift
+                VERSION=${RELEASE}
+                shift
+                ;;
+            -v)
+                shift
+                if test $# -gt 0; then
+                    VERSION=$1
+                    INSTALL_SPECIFIC_VERSION="1"
+                else
+                    echo "no version specified"
+                    exit 1
+                fi
+                shift
+                ;;
+            --version*)
+                VERSION=`echo $1 | sed -e 's/^[^=]*=//g'`
+                INSTALL_SPECIFIC_VERSION="1"
+                shift
+                ;;
+            *)
+               echo "$1 is not a recognized flag!"
+               exit -1
+               ;;
+      esac
+done
+
+function install_shaded_library() {
+    if [ -z "$M2_HOME" ]; then
+        echo "Please set M2_HOME"
+        exit 1
+    fi
+    SHADED_JAR="maven-lifecycle-extension-${VERSION}-shaded.jar"
+    wget http://central.maven.org/maven2/org/arquillian/smart/testing/maven-lifecycle-extension/${VERSION}/${SHADED_JAR}
+    read -r -p "We want to move shaded jar to M2_HOME with sudo. Can we? [y/N] " response
+    case "$response" in
+        [yY][eE][sS]|[yY])
+              sudo mv $SHADED_JAR $M2_HOME/lib/ext
+            ;;
+        *)
+            ;;
+    esac
+}
+
+function install_extension() {
+
+    # Needs to be without new lines, otherwise my sed skills below will fail badly :\
+    EXTENSION="<extension><groupId>org.arquillian.smart.testing</groupId><artifactId>maven-lifecycle-extension</artifactId><version>${VERSION}</version></extension>"
+
+    if [ ! -f .mvn/extensions.xml ]; then
+        echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?>
+            <extensions>
+              ${EXTENSION}
+            </extensions>" > .mvn/extensions.xml
+    else
+        EXTENSION_REGISTERED=$(cat .mvn/extensions.xml | grep 'org.arquillian.smart.testing' -A 2 |  grep -oPm1 "(?<=<version>)[^<]+");
+
+        if [ ! ${EXTENSION_REGISTERED} ]; then
+            EXTENSION=$(echo ${EXTENSION} | sed -e "s#/#\\\/#g");
+            sed -i -E 's/(.*<extensions>)(.*)/\1\n'$EXTENSION'\2/g' .mvn/extensions.xml
+        else
+            echo -e "Extension already registered with version ${EXTENSION_REGISTERED}\c"
+
+            if [ ${INSTALL_SPECIFIC_VERSION} -eq 1 ]; then
+                if [ "${EXTENSION_REGISTERED}" != "${VERSION}" ]; then
+                    echo -e " - overwritting with ${VERSION}\c"
+                    override_version $VERSION
+                fi
+                echo "."
+            elif [ $EXTENSION_REGISTERED != $LATEST ]; then
+                read -r -p ". Do you want to override with latest ${LATEST}? [y/N] " response
+                case "$response" in
+                    [yY][eE][sS]|[yY])
+                          override_version ${LATEST}
+                        ;;
+                    *)
+
+                        ;;
+                esac
+            else
+                echo " which is the latest stable version."
+            fi
+        fi
+    fi
+
+    mv .mvn/extensions.xml .mvn/extensions-unformatted.xml
+    xmllint --format .mvn/extensions-unformatted.xml > .mvn/extensions.xml
+    rm .mvn/extensions-unformatted.xml
+}
+
+function override_version() {
+    cat .mvn/extensions.xml | awk -v groupId="org.arquillian.smart.testing" -v version=$1 -v RS="</extension>" '
+      $0 ~ "<groupId>" groupId "</groupId>" {
+        sub("<version>.*</version>", "<version>" version "</version>")
+      }
+      {printf "%s", $0 RS}' | sed '$ d' > .mvn/extensions-new.xml
+    mv .mvn/extensions-new.xml .mvn/extensions.xml
+}
+
+## MAIN LOGIC
+
+MVN_VERSION=$(mvn --version | head -n1 | cut -d' ' -f3)
+echo $MVN_VERSION
+
+if [[ $MVN_VERSION =~ ^[3].[3-9].[0-9]$ ]]; then
+    install_extension
+elif [[ $MVN_VERSION =~ ^[3].[1-2].[0-9]$ ]]; then
+    install_shaded_library
+else
+    echo "Version ${MVN_VERSION} is not supported.";
+fi
+