from typing import Iterable

from dial_xl.events import (
    Event,
    ObservableNode,
    ObservableObserver,
    notify_observer,
)
from dial_xl.reader import _Reader
from dial_xl.utils import _escape_field_name, _unescape_field_name


class _OverrideHeader:
    __before: str = ""
    __name: str
    __after: str = "\n"

    def __init__(self, name: str):
        self.__name = name

    @property
    def before(self) -> str:
        return self.__before

    @property
    def name(self) -> str:
        return self.__name

    @name.setter
    def name(self, value: str):
        self.__name = value

    @property
    def after(self) -> str:
        return self.__after

    @after.setter
    def after(self, value: str):
        self.__after = value

    def to_dsl(self) -> str:
        """Converts the override to DSL format."""

        return f"{self.__before}{self.__name}{self.__after}"

    @classmethod
    def _deserialize(cls, reader: _Reader) -> "_OverrideHeader":
        result = cls("")
        result.__before = reader.next(lambda d: d["span"]["from"])
        result.__name = reader.next(lambda d: d["span"]["to"])
        result.__after = reader.till_linebreak()

        return result


class _Override:
    __before: str = ""
    __override: str
    __after: str = "\n"

    def __init__(self, value: str):
        self.__value = value

    @property
    def override(self) -> str:
        return self.__value

    @override.setter
    def override(self, value: str):
        self.__value = value

    @property
    def after(self) -> str:
        return self.__after

    @after.setter
    def after(self, value: str):
        self.__after = value

    def to_dsl(self) -> str:
        """Converts the override to DSL format."""

        return f"{self.__before}{self.__value}{self.__after}"

    @classmethod
    def _deserialize(cls, reader: _Reader) -> "_Override":
        result = cls("")
        result.__before = reader.next(lambda d: d["span"]["from"])
        result.__value = reader.next(lambda d: d["span"]["to"])
        result.__after = reader.till_linebreak()

        return result


class _OverrideLine:
    __overrides: list[_Override]

    def __init__(self, overrides: list[_Override]):
        self.__overrides = overrides

    @property
    def overrides(self) -> list[_Override]:
        return self.__overrides

    def to_dsl(self) -> str:
        """Converts the override to DSL format."""

        return f"{''.join(override.to_dsl() for override in self.__overrides)}"

    @classmethod
    def _deserialize(cls, reader: _Reader) -> "_OverrideLine":
        result = cls([])
        for index, value_entity in enumerate(reader.entity):
            value_reader = reader.with_entity(value_entity)
            value = _Override._deserialize(value_reader)
            result.__overrides.append(value)
            reader.position = value_reader.position
        return result


class _Overrides:
    __before: str = ""
    __prefix: str = "override\n"
    __headers: list[_OverrideHeader]
    __lines: list[_OverrideLine]

    def __init__(self):
        self.__headers = []
        self.__lines = []

    def to_dsl(self) -> str:
        """Converts the override to DSL format."""

        return (
            f"{self.__before}"
            f"{self.__prefix}"
            f"{''.join(header.to_dsl() for header in self.__headers)}"
            f"{''.join(line.to_dsl() for line in self.__lines)}"
        )

    @property
    def headers(self) -> list[_OverrideHeader]:
        return self.__headers

    @property
    def lines(self) -> list[_OverrideLine]:
        return self.__lines

    @classmethod
    def _deserialize(cls, reader: _Reader) -> "_Overrides":
        result = cls()
        result.__before = reader.next(lambda d: d["span"]["from"])
        result.__prefix = reader.before_next()
        for index, header_entity in enumerate(reader.entity.get("headers", [])):
            header_reader = reader.with_entity(header_entity)
            header = _OverrideHeader._deserialize(header_reader)
            result.__headers.append(header)
            reader.position = header_reader.position

        for index, line_entity in enumerate(reader.entity.get("values", [])):
            line_reader = reader.with_entity(line_entity)
            line = _OverrideLine._deserialize(line_reader)
            result.__lines.append(line)
            reader.position = line_reader.position

        return result


class Override(ObservableNode):
    __values: dict[str, str]
    __row_number: str | None = None

    def __init__(
        self,
        values: dict[str, str] | None = None,
        row_number: str | None = None,
    ):
        self.__values = values or {}
        self.__row_number = row_number

    @property
    def names(self) -> Iterable[str]:
        return self.__values.keys()

    @property
    def row_number(self) -> str | None:
        return self.__row_number

    @row_number.setter
    @notify_observer
    def row_number(self, value: str | None):
        """Set the row number of the override and invalidates compilation/computation results and sheet parsing errors"""

        self.__row_number = value

    def __getitem__(self, key: str) -> str:
        return self.__values.get(key)

    @notify_observer
    def __setitem__(self, key: str, value: str):
        self.__values[key] = value

    @notify_observer
    def __delitem__(self, key: str):
        del self.__values[key]


class Overrides(ObservableObserver):
    __overrides: _Overrides
    __row_position: int | None = None
    __field_names: list[str]
    __lines: list[Override]

    def __init__(self):
        self.__overrides = _Overrides()
        self.__field_names = []
        self.__lines = []

    @property
    def field_names(self) -> Iterable[str]:
        return (
            _unescape_field_name(name)
            for name in self.__field_names
            if name != "row"
        )

    @property
    def row_position(self) -> int | None:
        return self.__row_position

    def __len__(self):
        return len(self.__lines)

    def __getitem__(self, index: int) -> Override:
        return self.__lines[index]

    @notify_observer
    def __setitem__(self, index: int, value: Override):
        if index >= len(self.__lines):
            raise IndexError("Override line index out of range")

        old = self.__lines[index]
        old._detach()
        self.__overrides.lines[index] = self._attach_override_line(value)
        self.__lines[index] = value

    @notify_observer
    def __delitem__(self, index: int):
        self.__overrides.lines.pop(index)
        override = self.__lines.pop(index)
        override._detach()

    @notify_observer
    def append(self, value: Override):
        self.__overrides.lines.append(self._attach_override_line(value))
        self.__lines.append(value)

    def _attach_override_line(self, value) -> _OverrideLine:
        if value.row_number is not None:
            self._add_empty_if_missing("row")
        for name in value.names:
            self._add_empty_if_missing(_escape_field_name(name))
        values: list[_Override] = []
        for index, name in enumerate(self.__field_names):
            if index > 0:
                values[index - 1].after = ","
            if _unescape_field_name(name) in value.names:
                values.append(_Override(value[_unescape_field_name(name)]))
            elif name == "row":
                values.append(_Override(value.row_number or ""))
            else:
                values.append(_Override(""))
        value._attach(self)

        return _OverrideLine(values)

    def _add_empty_if_missing(self, name):
        if name not in self.__field_names:
            if name == "row":
                self.__row_position = len(self.__field_names)
            self.__field_names.append(name)
            if len(self.__overrides.headers) > 0:
                self.__overrides.headers[-1].after = ","
            self.__overrides.headers.append(_OverrideHeader(name))
            for line in self.__overrides.lines:
                if len(line.overrides) > 0:
                    line.overrides[-1].after = ","
                line.overrides.append(_Override(""))

    def to_dsl(self) -> str:
        """Converts the manual overrides to DSL format."""

        return self.__overrides.to_dsl()

    def _notify_before(self, event: Event):
        if self._observer:
            self._observer._notify_before(event)

        sender = event.sender
        if isinstance(sender, Override):
            if event.method_name == "__setitem__":
                self._on_override_update(
                    self.__lines.index(sender),
                    _escape_field_name(event.kwargs["key"]),
                    event.kwargs["value"],
                )
            elif event.method_name == "__delitem__":
                self._on_override_remove(
                    self.__lines.index(sender),
                    _escape_field_name(event.kwargs["key"]),
                )
            elif event.method_name == "row_number":
                if event.kwargs["value"] is None:
                    self._on_override_remove(self.__lines.index(sender), "row")
                else:
                    self._on_override_update(
                        self.__lines.index(sender), "row", event.kwargs["value"]
                    )

    def _set_overrides(self, overrides: _Overrides):
        self.__field_names = [header.name for header in overrides.headers]
        self.__row_position = next(
            (
                index
                for index, header in enumerate(overrides.headers)
                if header.name == "row"
            ),
            None,
        )
        self.__lines = [
            Override(
                values={
                    _unescape_field_name(
                        self.__field_names[index]
                    ): override.override
                    for index, override in enumerate(line.overrides)
                    if self.__row_position is None
                    or index != self.__row_position
                },
                row_number=(
                    line.overrides[self.__row_position].override
                    if self.__row_position is not None
                    else None
                ),
            )
            for line in overrides.lines
        ]
        for line in self.__lines:
            line._attach(self)
        self.__overrides = overrides

    def _on_override_update(self, index: int, name: str, value: str):
        self._add_empty_if_missing(name)
        position = self.__field_names.index(name)
        self.__overrides.lines[index].overrides[position].override = value

    def _on_override_remove(self, index: int, name: str):
        position = self.__field_names.index(name)
        self.__overrides.lines[index].overrides[position].override = ""
        last = True
        for line in self.__overrides.lines:
            if line.overrides[position].override != "":
                last = False
                break
        if last:
            removed_header = self.__overrides.headers.pop(position)
            if position > 0:
                self.__overrides.headers[
                    position - 1
                ].after = removed_header.after
            for line in self.__overrides.lines:
                removed_value = line.overrides.pop(position)
                if position > 0:
                    line.overrides[position - 1].after = removed_value.after
            self.__field_names.pop(position)

    @classmethod
    def _deserialize(cls, reader: _Reader) -> "Overrides":
        result = cls()
        result._set_overrides(_Overrides._deserialize(reader))
        return result