from __future__ import annotations

from PySide6.QtGui import QUndoCommand

from bedit_core.models import Component, EquationImplementation


class ChangeEquationTextCommand(QUndoCommand):
    COMMAND_ID = 1001

    def __init__(self, document: object, component: Component, section: str, text: list[str], edit_id: int) -> None:
        super().__init__(self._command_text(section))
        implementation = component.implementation
        if not isinstance(implementation, EquationImplementation):
            raise TypeError("equation text can only be changed on an equation component")

        self.document = document
        self.component = component
        self.section = section
        self.old_text = list(getattr(implementation, section))
        self.new_text = list(text)
        self.edit_id = edit_id

    def id(self) -> int:
        return self.COMMAND_ID

    def mergeWith(self, other: QUndoCommand) -> bool:
        if not isinstance(other, ChangeEquationTextCommand):
            return False
        if other.component is not self.component or other.section != self.section or other.edit_id != self.edit_id:
            return False
        self.new_text = list(other.new_text)
        return True

    def redo(self) -> None:
        self._set_text(self.new_text)

    def undo(self) -> None:
        self._set_text(self.old_text)

    def _set_text(self, text: list[str]) -> None:
        implementation = self.component.implementation
        assert isinstance(implementation, EquationImplementation)
        setattr(implementation, self.section, list(text))
        self.document.equation_text_changed.emit(self.component, self.section)

    @staticmethod
    def _command_text(section: str) -> str:
        return {
            "declarations": "Edit declarations",
            "initial_equations": "Edit initial equations",
            "equations": "Edit equations",
        }[section]