gitcatfile

#!/usr/bin/env groovy
import java.util.zip.DataFormatException
import java.util.zip.Inflater

def cli = new CliBuilder(usage: 'gitcatfile [-e <PATH>]')

cli.with {
    h longOpt: 'help', 'Show usage information'
    e longOpt: 'extract', args: 1, argName: 'extract', 'Extracts the object in given path'
}

extract = ""

def options = cli.parse(args)
if (!options) {
    return
}
if (options.h) {
    cli.usage()
    return
}
if (options.e) {
    extract = options.extract
} else {
    cli.usage()
    return
}

if (extract) {
    def file = new File(extract)
    if (! file.exists()) {
        println "Object file does not exist in ${file.absolutePath}"
        return
    }
    decompress(file.bytes)
}

def decompress(byte[] data) throws IOException, DataFormatException {
    Inflater inflater = new Inflater()
    inflater.setInput(data)

    ByteArrayOutputStream outputStream = new ByteArrayOutputStream(data.length)
    byte[] buffer = new byte[1024]
    while (!inflater.finished()) {
        int count = inflater.inflate(buffer)
        outputStream.write(buffer, 0, count)
    }
    outputStream.close()
    byte[] output = outputStream.toByteArray()

    def normalizedOutput = []

    def isHex = false
    def hexCount = 0
    def isHeader = true
    output.each {
        if (it == 0 && !isHex) {
            normalizedOutput << "\\0 "
            if (!isHeader) {
                isHex = true
            } else {
                normalizedOutput << "\n"
            }
            isHeader = false
        } else if (isHex & hexCount <= 20 ) {
            normalizedOutput << String.format("%02x", it&0xff)

            hexCount++
            if (hexCount == 20) {
                hexCount = 0
                isHex = false
                normalizedOutput << "\n"
            }
        } else {
            normalizedOutput << new String(it)
        }
    }
    normalizedOutput.each {
        print it
    }
}