def filewrapper(file, mode):
    if type(file) is str:
        return open(file, mode)
    elif hasattr(file, "read"):
        return file
    else:
        raise ValueError("need string or file descriptor object")

class FileParsingError(SyntaxError):
    pass

class Record:
    def __init__(self):
        self.name = None
        self.data = {}

        self.children = {}
        self.parents = {}

    def __getitem__(self, item):
        return self.data[item]

    def __setitem__(self, item, value):
        self.data[item] = value

    def __repr__(self):
        return f"[{self.data}, {len(self.children)}, {len(self.parents)}]"

class RecordCollection():
    def __init__(self, file):
        with filewrapper(file, "r") as fd:
            self._fromFile(fd)
            self._parent()

    def _fromFile(self, fd):
        lines = [i.rstrip() for i in fd.readlines()]
        self.objects = {}
        current = Record()

        for i in lines:
            ind = i[0:2] == '  '

            if ind:
                spl = i[2:].split(': ')
                try:
                    current[spl[0]] = spl[1]
                except IndexError:
                    # TODO: maybe add line numbers?
                    raise FileParsingError(f"error parsing '{i}'")

            else:
                try:
                    name = i.split(' ')[1][0:-1]
                except IndexError:
                    current = Record()
                    continue

                current.name = name
                self.objects[name] = current

    def _parent(self):
        for i in self.objects:
            current = self.objects[i]
            try:
                inherit = current['inherit'].split(' ')
                inherit_order = \
                    [int(i) for i in current['inherit_order'].split(' ')]

                # TODO: add more precise error checking
                if not len(inherit) == len(inherit_order):
                    raise FileParsingError("len(inherit) != len(inherit_order)")

                for j, k in zip(
                    inherit,
                    inherit_order
                ):

                    current.parents[j] = self.objects[j]
                    self.objects[j].children[k] = current

            except KeyError:
                pass

    def findEntrypoints(self):
        ret = []

        for i in self.objects:
            if not self.objects[i].parents:
                ret.append(self.objects[i])

        return ret

    def write(self, file):
        with filewrapper(file, "w") as fd:
            lines = []
            for i in self.objects:
                if self.objects[i].children:
                    lines.append(f"cat {self.objects[i].name}:")
                else:
                    lines.append(f"rec {self.objects[i].name}:")

                for j in self.objects[i].data:
                    lines.append(
                        f"  {j}: {self.objects[i].data[j]}"
                    )

                lines.append("")

            lines.pop()

            for i in range(len(lines)):
                lines[i] += "\n"

            fd.writelines(lines)