from __future__ import annotations

import re

from PySide6.QtGui import QTextCursor
from PySide6.QtWidgets import QMessageBox, QPlainTextEdit

from main_window.constants import _NEXT_CHECK_RE


class UIHelpersMixin:
    def _safe(self, fn, *, title: str = "Error"):
        try:
            return fn()
        except Exception as e:  # pragma: no cover - GUI
            try:
                self.ctrl.log_gui(f"[ui-error] {title}: {e}")
            except Exception:
                pass
            QMessageBox.critical(self, title, str(e))
            return None

    def _set_text(self, widget: QPlainTextEdit, text: str, *, preserve_scroll: bool = False) -> None:
        """Set text, optionally сохраняя положение скролла (для trace)."""
        if not preserve_scroll:
            widget.setPlainText(text)
            return

        sb = widget.verticalScrollBar()
        old_max = sb.maximum()
        old_val = sb.value()
        at_end = old_val >= old_max - 2

        widget.setPlainText(text)

        new_max = sb.maximum()
        if at_end:
            sb.setValue(new_max)
        else:
            # подвинем на ту же относительную позицию, учитывая прирост размера
            sb.setValue(max(0, min(new_max, old_val+(new_max-old_max))))

    def _append_text(self, widget: QPlainTextEdit, text: str) -> None:
        cursor = widget.textCursor()
        cursor.movePosition(QTextCursor.End)
        cursor.insertText(text)
        widget.setTextCursor(cursor)
        widget.ensureCursorVisible()

    def _clean_ui_lines(self, lines) -> str:
        buf = "\n".join([str(x) for x in (lines or [])]).replace("\r", "\n")
        out_lines = []
        for ln in buf.splitlines():
            t = ln.strip()
            if not t:
                continue
            t2 = _NEXT_CHECK_RE.sub("", t).strip()
            if not t2:
                continue
            out_lines.append(t2)
        return "\n".join(out_lines).rstrip()