"""Affichage de plusieurs terminaux dans un meme onglet (split), via des
QSplitter imbriques.

Un SplitContainer prend la place d'un onglet normal dans le QTabWidget de
ConnectionController ; chaque panneau (PaneSlot) heberge un widget d'onglet
existant (SessionTabWidget, LocalTerminalTabWidget, ...) sans le modifier.
"""
from __future__ import annotations

from typing import Callable

from PySide6.QtCore import Qt, Signal
from PySide6.QtWidgets import (
    QWidget, QVBoxLayout, QHBoxLayout, QSplitter, QToolButton, QFrame,
)

LAYOUT_SINGLE = "1"
LAYOUT_2V = "2v"  # 2 panneaux cote a cote (ligne de separation verticale)
LAYOUT_2H = "2h"  # 2 panneaux empiles (ligne de separation horizontale)
LAYOUT_4 = "4"    # grille 2x2

LAYOUT_LABELS = {
    LAYOUT_2V: "2 panneaux verticaux (cote a cote)",
    LAYOUT_2H: "2 panneaux horizontaux (empiles)",
    LAYOUT_4: "4 panneaux",
}

_PANE_COUNTS = {LAYOUT_SINGLE: 1, LAYOUT_2V: 2, LAYOUT_2H: 2, LAYOUT_4: 4}


class PaneSlot(QWidget):
    """Un emplacement dans la grille : une fine barre (menu + fermeture)
    au-dessus du contenu, qui reste un widget d'onglet inchange."""

    close_requested = Signal(object)   # emet elle-meme
    menu_requested = Signal(object)    # emet elle-meme ; le conteneur construit le menu

    def __init__(self, content: QWidget, parent=None):
        super().__init__(parent)
        layout = QVBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(0)

        bar = QHBoxLayout()
        bar.setContentsMargins(4, 2, 4, 2)
        self.menu_btn = QToolButton()
        self.menu_btn.setText("☰")
        self.menu_btn.setToolTip("Changer le contenu de ce panneau")
        self.menu_btn.clicked.connect(lambda: self.menu_requested.emit(self))
        bar.addWidget(self.menu_btn)
        bar.addStretch()
        close_btn = QToolButton()
        close_btn.setText("✕")
        close_btn.setToolTip("Fermer ce panneau")
        close_btn.clicked.connect(lambda: self.close_requested.emit(self))
        bar.addWidget(close_btn)
        bar_frame = QFrame()
        bar_frame.setObjectName("tabBar")
        bar_frame.setLayout(bar)
        layout.addWidget(bar_frame)

        self.content = content
        layout.addWidget(content, 1)

    def close_connection(self) -> None:
        if hasattr(self.content, "close_connection"):
            self.content.close_connection()

    def set_content(self, new_content: QWidget) -> None:
        self.layout().replaceWidget(self.content, new_content)
        self.content.setParent(None)
        self.content = new_content
        new_content.show()


class SplitContainer(QWidget):
    """Grille de terminaux (1/2/4 panneaux). Redescend automatiquement a un
    seul panneau quand il n'en reste plus qu'un (ferme les autres)."""

    all_panes_closed = Signal(object)     # (widget restant) -> le proprietaire deplie l'onglet
    pane_menu_requested = Signal(object, object)  # (pane, container) -> le proprietaire affiche un menu

    def __init__(self, first_widget: QWidget, layout_kind: str, make_filler: Callable[[], QWidget], parent=None):
        super().__init__(parent)
        self.panes: list[PaneSlot] = []
        self._root_layout = QVBoxLayout(self)
        self._root_layout.setContentsMargins(0, 0, 0, 0)
        self._root_layout.setSpacing(0)

        contents = [first_widget] + [make_filler() for _ in range(_PANE_COUNTS[layout_kind] - 1)]
        for content in contents:
            self._add_pane(content)
        self._root_layout.addWidget(self._arrange(layout_kind, self.panes))

    def _make_pane(self, content: QWidget) -> PaneSlot:
        pane = PaneSlot(content)
        pane.close_requested.connect(self._on_pane_close_requested)
        pane.menu_requested.connect(lambda p: self.pane_menu_requested.emit(p, self))
        return pane

    def _add_pane(self, content: QWidget) -> PaneSlot:
        pane = self._make_pane(content)
        self.panes.append(pane)
        return pane

    @staticmethod
    def _arrange(layout_kind: str, panes: list[PaneSlot]) -> QWidget:
        if layout_kind == LAYOUT_SINGLE:
            return panes[0]
        if layout_kind == LAYOUT_2V:
            splitter = QSplitter(Qt.Horizontal)
        elif layout_kind == LAYOUT_2H:
            splitter = QSplitter(Qt.Vertical)
        elif layout_kind == LAYOUT_4:
            top = QSplitter(Qt.Horizontal)
            top.addWidget(panes[0])
            top.addWidget(panes[1])
            bottom = QSplitter(Qt.Horizontal)
            bottom.addWidget(panes[2])
            bottom.addWidget(panes[3])
            outer = QSplitter(Qt.Vertical)
            outer.addWidget(top)
            outer.addWidget(bottom)
            return outer
        else:
            raise ValueError(f"layout de split inconnu : {layout_kind}")
        for pane in panes:
            splitter.addWidget(pane)
        return splitter

    def replace_pane_content(self, pane: PaneSlot, new_content: QWidget) -> None:
        """Ferme l'ancien contenu du panneau et le remplace (ex : terminal
        local par defaut remplace par un onglet deplace ici)."""
        pane.close_connection()
        pane.set_content(new_content)

    def _on_pane_close_requested(self, pane: PaneSlot) -> None:
        pane.close_connection()
        self.panes.remove(pane)
        # Le retirer de son QSplitter suffit : celui-ci redistribue l'espace
        # aux panneaux restants tout seul, sans reconstruire toute la grille.
        pane.setParent(None)
        pane.deleteLater()
        if len(self.panes) <= 1:
            remaining = self.panes[0].content if self.panes else None
            self.all_panes_closed.emit(remaining)

    def close_all(self) -> None:
        for pane in self.panes:
            pane.close_connection()