import io
from .matcher import SignatureMatcher, Match

class FlattenDeviceTree(SignatureMatcher):
    def __init__(self, file):
        self.name = "Flatten Device Tree"
        self.signature = b'\xd0\x0d\xfe\xed'
        super().__init__(file)

    def is_valid(self):
        for match in self.search():
            start = match
            header = io.BytesIO(self.file[start:start+4*10])
            magic = header.read(4)
            totalsize = header.read(4)
            off_dt_struct = header.read(4)
            off_dt_strings = header.read(4)
            off_mem_rsvmap = header.read(4)
            version = header.read(4)
            last_comp_version = header.read(4)
            boot_cpuid_phys = header.read(4)
            size_dt_strings = header.read(4)
            size_dt_struct = header.read(4)

            totalsize = int.from_bytes(totalsize, 'little')
            self.matches += [Match(start, totalsize)]

        return len(self.matches) != 0