osgi.gradle

import java.nio.file.attribute.FileTime
import java.util.jar.Attributes
import java.util.jar.JarEntry
import java.util.jar.JarFile
import java.util.jar.JarOutputStream
import java.util.jar.Manifest

import static java.util.Calendar.FEBRUARY

apply plugin: 'biz.aQute.bnd.builder'

jar {
    classpath = project.configurations.runtime
    bnd(
        'Bundle-Name': 'Mockito Mock Library for Java. Core bundle requires Byte Buddy and Objenesis.',
        'Bundle-SymbolicName': 'org.mockito.mockito-core',
        'Bundl-version': project.version.replace('-', '.'),
        '-versionpolicy': '[${version;==;${@}},${version;+;${@}})',
        'Export-Package': "!org.mockito.internal.*,org.mockito.*;version=${version}",
        'Import-Package': [
                'net.bytebuddy.*;version="[1.6.0,2.0)"',
                'junit.*;resolution:=optional',
                'org.junit.*;resolution:=optional',
                'org.hamcrest;resolution:=optional',
                'org.objenesis;version="[2.5,3.0)"',
                'org.opentest4j.*;resolution:=optional',
                'org.mockito.*'
        ].join(','),
        '-removeheaders': 'Private-Package',
        'Automatic-Module-Name': 'org.mockito'
    )
}

jar.doLast {
    JarFile originalJar = new JarFile(jar.archivePath)

    new RemoveOsgiLastModifiedHeader(originalJar)
        .transform()
        .renameTo jar.archivePath
}


/*
 * The OSGi plugin in Gradle 5.3 has a known issue (https://github.com/gradle/gradle/issues/6187) where it embeds
 * a Manifest entry "Bnd-LastModified" (set to the last modified time of the build directory) even if you ask it not to
 * using `-noextraheaders` or `-removeheaders`.
 *
 * It cannot be pinned or removed, and is a source of non-determinism in the build.
 *
 * This class addresses the problem by rewriting the JAR and removing that entry from the Manifest. A side-effect of this
 * is having to set `lastModifiedTime` for each entry to a fixed value, else this would also introduce non-determinism.
 *
 * The fixed value is the same as the default value for Gradle's fixed timestamps, and the rationale behind it is detailed
 * in https://github.com/gradle/gradle/blob/58538513a3bff3b7015718976fe1304e23f40694/subprojects/core/src/main/java/org/gradle/api/internal/file/archive/ZipCopyAction.java#L42-L57
 */

class RemoveOsgiLastModifiedHeader {
    private final long CONSTANT_TIME_FOR_ZIP_ENTRIES = new GregorianCalendar(1980, FEBRUARY, 1, 0, 0, 0).timeInMillis

    private final JarFile artifact

    RemoveOsgiLastModifiedHeader(JarFile artifact) {
        this.artifact = artifact
    }

    File transform() {
        File temp = File.createTempFile("temp",".jar")

        temp.withOutputStream { os ->
            JarOutputStream stream = new JarOutputStream(os)

            this.artifact
                .entries()
                .sort { it.name }
                .each { JarEntry entry ->

                    stream.putNextEntry(newJarEntry(entry))

                    if (entry.name == "META-INF/MANIFEST.MF") {
                        newManifest(entry).write(stream)
                    } else {
                        stream << this.artifact.getInputStream(entry)
                    }

                    stream.closeEntry()
                }

            stream.finish()
        }

        temp
    }

    Manifest newManifest(JarEntry entry) {
        Manifest manifest = new Manifest()

        manifest.read(this.artifact.getInputStream(entry))

        manifest
            .getMainAttributes()
            .remove(new Attributes.Name("Bnd-LastModified"))

        manifest
    }

    JarEntry newJarEntry(JarEntry original) {
        JarEntry newEntry = new JarEntry(original.name)

        newEntry.setLastModifiedTime(FileTime.fromMillis(CONSTANT_TIME_FOR_ZIP_ENTRIES))

        newEntry
    }

}