"""Bảng Kanban 7 cột kéo thả — R08-T11.

Bảy trạng thái task xếp thành bảy cột. Kéo thẻ sang cột khác là **đổi trạng
thái thật**, không phải chỉ dời chỗ trên màn hình — thả vào cột "Đang chạy"
là task chạy ngay.

``_DropZone`` là vùng nhận file kéo vào, dùng chung với hộp thoại nhập task.
"""
from __future__ import annotations

import copy
from pathlib import Path
from typing import Dict, List, Optional
from PySide6.QtCore import Qt, Signal
from PySide6.QtWidgets import (
    QAbstractItemView, QComboBox, QDialog, QDialogButtonBox, QHBoxLayout,
    QLabel, QLineEdit, QListWidget, QListWidgetItem, QMenu, QMessageBox,
    QPlainTextEdit, QPushButton, QScrollArea, QSizePolicy, QStackedWidget,
    QTabBar, QTableWidget, QTableWidgetItem, QVBoxLayout, QWidget,
)
from ...core import tasks as taskrepo
from ...core.projects import list_projects
from ...core.tasks import STATUSES, chain_error, duplicate_task, new_task
from ...core.worker import AgentWorker
from ...i18n import on_language_changed, tr
from ...state import AppContext
from ...theme import current_palette
from ...ui.calendar_view import CalendarView
from ...ui.icons import icon
from ...ui.osutil import open_path


class _KanbanColumn(QListWidget):
    """One status lane. Accepts drops from sibling columns; a drop means
    'move this task to my status'."""

    task_dropped = Signal(str, str)   # task_id, new_status

    def __init__(self, status: str):
        super().__init__()
        self.status = status
        self.setDragDropMode(QAbstractItemView.DragDrop)
        self.setDefaultDropAction(Qt.MoveAction)
        # Shift/Ctrl-click several cards in the SAME column, then right-click
        # → "Delete N selected" to bulk-remove tasks instead of one at a time.
        self.setSelectionMode(QAbstractItemView.ExtendedSelection)
        self.setWordWrap(True)
        # Cards wrap, so there is never anything to reach by scrolling sideways
        # — but QListWidget's own column hint runs 1-6px past the viewport, and
        # a lane sprouted a horizontal scrollbar at 36 of 38 window widths I
        # measured. Which lanes grew one changed with the width, which is why it
        # looked like it depended on the screen.
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setResizeMode(QListWidget.Adjust)   # re-wrap on every resize
        # No pixel floor here. A fixed one is always wrong on some screen:
        # 190 lost the seventh lane, 150 still wanted 1242px where a 1280
        # window leaves 1091 — so the 1280 monitor scrolled sideways and the
        # 1920 one did not, same app, same build. The board divides whatever
        # width it has by seven instead; see _fit_lanes().

    def dropEvent(self, event):  # noqa: N802
        source = event.source()
        if isinstance(source, _KanbanColumn) and source is not self:
            item = source.currentItem()
            tid = item.data(Qt.UserRole) if item else None
            if tid:
                event.acceptProposedAction()
                self.task_dropped.emit(tid, self.status)
                return
        event.ignore()


class _DropZone(QLabel):
    """Drag-an-.xlsx-here area for the Import tab."""

    file_dropped = Signal(str)

    def __init__(self):
        super().__init__()
        self.setAlignment(Qt.AlignCenter)
        self.setMinimumHeight(70)
        _p = current_palette()
        self.setStyleSheet(
            f"QLabel {{ border: 1px dashed {_p.border_strong};"
            f" border-radius: {_p.radius_lg}px;"
            f" color: {_p.text_muted}; padding: 10px; }}")
        self.setAcceptDrops(True)

    def dragEnterEvent(self, event):  # noqa: N802
        urls = event.mimeData().urls()
        if urls and urls[0].toLocalFile().lower().endswith(
                (".xlsx", ".xlsm", ".xls", ".csv", ".json")):
            event.acceptProposedAction()

    def dropEvent(self, event):  # noqa: N802
        urls = event.mimeData().urls()
        if urls:
            self.file_dropped.emit(urls[0].toLocalFile())