import groovy.json.JsonOutput

import java.util.regex.Pattern

def collectLicenses(File rootDir, File ossPluginResDir, File outDir) {

    def pattern = Pattern.compile("^(\\d+:\\d+) (.*)\$")

    // third_party_licenses file generated by oss-licenses-plugin
    def licenses = new File(ossPluginResDir, "third_party_licenses")

    // third_party_license_metadata file generated by oss-licenses-plugin
    def metadata = new File(ossPluginResDir, "third_party_license_metadata")

    // check that files exist, are readable and output directory is writable
    if (!licenses.canRead()) {
        throw new GradleException("Cannot find/read ${licenses.absolutePath}")
    }

    if (!metadata.canRead()) {
        throw new GradleException("Cannot find/read ${metadata.absolutePath}")
    }

    if (!outDir.exists() || !outDir.canExecute()) {
        if (!outDir.mkdir()) {
            throw new GradleException("Failed to create ${outDir.absolutePath}")
        }
    }

    def outFile = new File(outDir, "android.json")
    if (outFile.exists()) {
        outFile.delete()
    }

    println "Used licenses:"
    var licenseMap = [:]
    var index = 0
    licenses.eachLine { line ->
        def indices = "$index:${line.length()}"
        println line
        licenseMap[indices] = line
        index += line.length() + 1
    }

    println "Modules:"
    def licenseList = []
    metadata.eachLine { line ->
        def matcher = pattern.matcher(line)
        if (matcher.find()) {
            def indices = matcher.group(1)
            def packageName = matcher.group(2)
            if (licenseMap.get(indices) == null) {
                throw new GradleException("Unexpected license indexes: $indices for $packageName")
            }
            println packageName + " license: ${licenseMap[indices]}"
            licenseList.add(PackageName: packageName, PackageLicense: licenseMap[indices])
        } else {
            throw new GradleException("Unexpected project license line: $line")
        }
    }

    // add zxing_licenses which are not detected
    println "adding zxing licenses"
    licenseList.add(PackageName: "ZXing Core (3.5.2)", PackageLicense: "https://www.apache.org/licenses/LICENSE-2.0.txt")
    licenseList.add(PackageName: "ZXing Android Core (3.3.0)", PackageLicense: "https://www.apache.org/licenses/LICENSE-2.0.txt")

    outFile.write(new JsonOutput().toJson(licenseList))
    println "Created ${outFile.absolutePath}"

    // copy license assets to flutter resources
    def licensesDir = new File(rootDir, "licenses/")
    copy {
        from(licensesDir.absolutePath) {
            include "**/*txt"
            include "**/*json"
        }
        into outDir
    }

    // remove not needed oss-licenses-plugin files
    licenses.delete()
    metadata.delete()
}

tasks.register('collectLicenses') {
    dependsOn(":app:releaseOssLicensesTask")
    doLast {
        def ossPluginResDir = new File(project.buildDir, "generated/third_party_licenses/release/res/raw/")
        collectLicenses(project.rootDir, ossPluginResDir, new File(project.rootDir.parent, "assets/licenses/raw/"))
    }
}