from typing import List, Optional
from .parser import DecompParser
from .error import ParserAlert, ParserError
from .node import ParserSymbol


def get_checkorder_filter(module):
    """Return a filter function on implemented functions in the given module"""
    return lambda fun: fun.module == module and not fun.lookup_by_name


class DecompLinter:
    def __init__(self) -> None:
        self.alerts: List[ParserAlert] = []
        self._parser = DecompParser()
        self._filename: str = ""
        self._module: Optional[str] = None
        # Set of (str, int) tuples for each module/offset pair seen while scanning.
        # This is _not_ reset between files and is intended to report offset reuse
        # when scanning the entire directory.
        self._offsets_used = set()

    def reset(self, full_reset: bool = False):
        self.alerts = []
        self._parser.reset()
        self._filename = ""
        self._module = None

        if full_reset:
            self._offsets_used.clear()

    def file_is_header(self):
        return self._filename.lower().endswith(".h")

    def _load_offsets_from_list(self, marker_list: List[ParserSymbol]):
        """Helper for loading (module, offset) tuples while the DecompParser
        has them broken up into three different lists."""
        for marker in marker_list:
            value = (marker.module, marker.offset)
            if value in self._offsets_used:
                self.alerts.append(
                    ParserAlert(
                        code=ParserError.DUPLICATE_OFFSET,
                        line_number=marker.line_number,
                        line=f"0x{marker.offset:08x}",
                    )
                )
            else:
                self._offsets_used.add(value)

    def _check_function_order(self):
        """Rules:
        1. Only markers that are implemented in the file are considered. This means we
        only look at markers that are cross-referenced with cvdump output by their line
        number. Markers with the lookup_by_name flag set are ignored because we cannot
        directly influence their order.

        2. Order should be considered for a single module only. If we have multiple
        markers for a single function (i.e. for LEGO1 functions linked statically to
        ISLE) then the virtual address space will be very different. If we don't check
        for one module only, we would incorrectly report that the file is out of order.
        """

        if self._module is None:
            return

        checkorder_filter = get_checkorder_filter(self._module)
        last_offset = None
        for fun in filter(checkorder_filter, self._parser.functions):
            if last_offset is not None:
                if fun.offset < last_offset:
                    self.alerts.append(
                        ParserAlert(
                            code=ParserError.FUNCTION_OUT_OF_ORDER,
                            line_number=fun.line_number,
                        )
                    )

            last_offset = fun.offset

    def _check_offset_uniqueness(self):
        self._load_offsets_from_list(self._parser.functions)
        self._load_offsets_from_list(self._parser.vtables)
        self._load_offsets_from_list(self._parser.variables)

    def _check_byname_allowed(self):
        if self.file_is_header():
            return

        for fun in self._parser.functions:
            if fun.lookup_by_name:
                self.alerts.append(
                    ParserAlert(
                        code=ParserError.BYNAME_FUNCTION_IN_CPP,
                        line_number=fun.line_number,
                    )
                )

    def check_lines(self, lines, filename, module=None):
        """`lines` is a generic iterable to allow for testing with a list of strings.
        We assume lines has the entire contents of the compilation unit."""

        self.reset(False)
        self._filename = filename
        self._module = module

        self._parser.read_lines(lines)

        self._parser.finish()
        self.alerts = self._parser.alerts[::]

        self._check_offset_uniqueness()

        if self._module is not None:
            self._check_byname_allowed()

            if not self.file_is_header():
                self._check_function_order()

        return len(self.alerts) == 0

    def check_file(self, filename, module=None):
        """Convenience method for decomplint cli tool"""
        with open(filename, "r", encoding="utf-8") as f:
            return self.check_lines(f, filename, module)