// TODO Simplify the buildTimestamp() calculation if possible
fun Project.buildTimestamp(): Provider<String> =
    providers.of(BuildTimestampValueSource::class) {
        parameters {
            buildTimestampFromBuildReceipt = buildTimestampFromBuildReceipt()
            buildTimestampFromGradleProperty = buildTimestamp
            runningOnCi = buildRunningOnCi

    @get:Input
    abstract val promotionBuild: Property<Boolean>

    @get:Input
    @get:Optional
    abstract val buildTimestamp: Property<Date>

    @get:OutputDirectory
    abstract val receiptFolder: DirectoryProperty

    fun buildTimestampFrom(provider: Provider<String>) {
        buildTimestamp = provider.map { buildTimestampString -> timestampFormat.parse(buildTimestampString) }
    }

    @TaskAction

abstract class ModuleIdentityExtension(val tasks: TaskContainer, val objects: ObjectFactory) {

    abstract val version: Property<GradleVersion>

    abstract val baseName: Property<String>

    abstract val buildTimestamp: Property<String>
    abstract val snapshot: Property<Boolean>
    abstract val promotionBuild: Property<Boolean>

    abstract val releasedVersions: Property<ReleasedVersionsDetails>

    fun createBuildReceipt() {

    }

    override fun obtain(): String? = parameters.run {
        buildReceiptString()
            ?.let(BuildReceipt::readBuildReceiptFromString)
            ?.let { buildReceipt ->
                buildReceipt["buildTimestamp"] as String
            }
    }

    override fun getDisplayName(): String =
        "the build timestamp extracted from the build receipt".let {
            when {

import java.util.Date
import java.util.TimeZone


data class ReleasedVersion(val version: String, val buildTime: String) {
    fun gradleVersion() = GradleVersion.version(version)
    fun buildTimeStamp(): Date = SimpleDateFormat("yyyyMMddHHmmssZ").apply { timeZone = TimeZone.getTimeZone("UTC") }.parse(buildTime)

        val latestRelease = listOf(releasedVersions.latestReleaseSnapshot, releasedVersions.latestRc).filter { it.gradleVersion() > latestFinalRelease.gradleVersion() }.maxByOrNull { it.buildTimeStamp() } ?: latestFinalRelease
        val previousVersions = (listOf(latestRelease) + releasedVersions.finalReleases).filter { it.gradleVersion() >= lowestInterestingVersion && it.gradleVersion().baseVersion < currentBaseVersion }.distinct()

        get() = parameters.run {
            when {
                buildTimestampFromBuildReceipt.isPresent -> "from build receipt"
                buildTimestampFromGradleProperty.isPresent -> "from buildTimestamp property"
                runningInstallTask.get() -> "from current time because installing"
                runningDocsTestTask.get() -> "from current time because testing docs"

    const val BUILD_PROMOTION_COMMIT_ID = "promotionCommitId"
    const val BUILD_RC_NUMBER = "rcNumber"
    const val BUILD_SERVER_URL = "BUILD_SERVER_URL"
    const val BUILD_TIMESTAMP = "buildTimestamp"
    const val BUILD_VCS_NUMBER = "BUILD_VCS_NUMBER"
    const val BUILD_VERSION_QUALIFIER = "versionQualifier"
    const val CI_ENVIRONMENT_VARIABLE = "CI"