cordova-android/bin/templates/project/cordova.gradle

/*
       Licensed to the Apache Software Foundation (ASF) under one
       or more contributor license agreements.  See the NOTICE file
       distributed with this work for additional information
       regarding copyright ownership.  The ASF licenses this file
       to you under the Apache License, Version 2.0 (the
       "License"); you may not use this file except in compliance
       with the License.  You may obtain a copy of the License at

         http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing,
       software distributed under the License is distributed on an
       "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
       KIND, either express or implied.  See the License for the
       specific language governing permissions and limitations
       under the License.
*/

import java.util.regex.Pattern

String getProjectTarget(String defaultTarget) {
    def manifestFile = file("project.properties")
    def pattern = Pattern.compile("target\\s*=\\s*(.*)")
    def matcher = pattern.matcher(manifestFile.getText())
    if (matcher.find()) {
        matcher.group(1)
    } else {
        defaultTarget
    }
}

String[] getAvailableBuildTools() {
    def buildToolsDir = new File(getAndroidSdkDir(), "build-tools")
    buildToolsDir.list()
        .findAll { it ==~ /[0-9.]+/ }
        .sort { a, b -> compareVersions(b, a) }
}

String latestBuildToolsAvailable(String minBuildToolsVersion) {
    def availableBuildToolsVersions
    try {
        availableBuildToolsVersions = getAvailableBuildTools()
    } catch (e) {
        println "An exception occurred while trying to find the Android build tools."
        throw e
    }
    if (availableBuildToolsVersions.length > 0) {
        def highestBuildToolsVersion = availableBuildToolsVersions[0]
        if (compareVersions(highestBuildToolsVersion, minBuildToolsVersion) < 0) {
            throw new RuntimeException(
                "No usable Android build tools found. Highest installed version is " +
                highestBuildToolsVersion + "; minimum version required is " +
                minBuildToolsVersion + ".")
        }
        highestBuildToolsVersion
    } else {
        throw new RuntimeException(
            "No installed build tools found. Please install the Android build tools version " +
            minBuildToolsVersion + " or higher.")
    }
}

// Return the first non-zero result of subtracting version list elements
// pairwise. If they are all identical, return the difference in length of
// the two lists.
int compareVersionList(Collection aParts, Collection bParts) {
    def pairs = ([aParts, bParts]).transpose()
    pairs.findResult(aParts.size()-bParts.size()) {it[0] - it[1] != 0 ? it[0] - it[1] : null}
}

// Compare two version strings, such as "19.0.0" and "18.1.1.0". If all matched
// elements are identical, the longer version is the largest by this method.
// Examples:
//   "19.0.0" > "19"
//   "19.0.1" > "19.0.0"
//   "19.1.0" > "19.0.1"
//   "19" > "18.999.999"
int compareVersions(String a, String b) {
    def aParts = a.tokenize('.').collect {it.toInteger()}
    def bParts = b.tokenize('.').collect {it.toInteger()}
    compareVersionList(aParts, bParts)
}

String getAndroidSdkDir() {
    def rootDir = project.rootDir
    def androidSdkDir = null
    String envVar = System.getenv("ANDROID_HOME")
    def localProperties = new File(rootDir, 'local.properties')
    String systemProperty = System.getProperty("android.home")
    if (envVar != null) {
        androidSdkDir = envVar
    } else if (localProperties.exists()) {
        Properties properties = new Properties()
        localProperties.withInputStream { instr ->
            properties.load(instr)
        }
        def sdkDirProp = properties.getProperty('sdk.dir')
        if (sdkDirProp != null) {
            androidSdkDir = sdkDirProp
        } else {
            sdkDirProp = properties.getProperty('android.dir')
            if (sdkDirProp != null) {
                androidSdkDir = (new File(rootDir, sdkDirProp)).getAbsolutePath()
            }
        }
    }
    if (androidSdkDir == null && systemProperty != null) {
        androidSdkDir = systemProperty
    }
    if (androidSdkDir == null) {
        throw new RuntimeException(
            "Unable to determine Android SDK directory.")
    }
    androidSdkDir
}

cordovaSdkVersion =  System.env.MIN_SDK_VERSION ?: getProjectTarget("android-19")
cordovaBuildToolsVersion = latestBuildToolsAvailable("19.1.0")