import io

from PyRomfsImage import *

from .matcher import SignatureMatcher, Match

class RomFS(SignatureMatcher):
    """
    RomFS a readonly file system
    big-endian
    https://www.kernel.org/doc/Documentation/filesystems/romfs.txt
    """
    def __init__(self, file):
        self.name = "RomFS"
        self.signature = b'-rom1fs-'
        super().__init__(file)

    def is_valid(self):
        for match in self.search():
            start = match
            header = io.BytesIO(self.file[start:start+14])
            magic = header.read(8)
            fullsize = header.read(4)
            checksum = header.read(4)
            fullsize = int.from_bytes(fullsize, 'big')
            self.matches += [Match(start, fullsize)]

        return len(self.matches) != 0

    def view(self, match):

        start = match.offset
        length = match.length
        raw = io.BytesIO(self.file[start:start+length])
        rom = Romfs(raw)
        root = rom.getRoot()
        print(root.name)
        for ch in root.children:
            print(ch.name)