"""
Process list viewer — shows running server processes with kill capability.
Auto-refresh support with configurable interval.
"""
from PyQt6.QtWidgets import (
    QWidget, QVBoxLayout, QHBoxLayout, QLabel, QPushButton,
    QTableWidget, QTableWidgetItem, QHeaderView, QCheckBox,
    QMessageBox,
)
from PyQt6.QtCore import Qt, pyqtSignal, QTimer

from app.utils.worker import SchemaWorker


class ProcessListPanel(QWidget):
    status_message = pyqtSignal(str)

    def __init__(self, driver, connection_name: str = "", parent=None):
        super().__init__(parent)
        self._driver = driver
        self._connection_name = connection_name
        self._refresh_timer = QTimer(self)
        self._refresh_timer.timeout.connect(self._refresh)
        self._build_ui()
        self._refresh()

    # ── UI ────────────────────────────────────────────────────────────────────

    def _build_ui(self):
        root = QVBoxLayout(self)
        root.setContentsMargins(0, 0, 0, 0)

        # Header bar
        hdr = QHBoxLayout()
        hdr.setContentsMargins(8, 6, 8, 4)

        title = QLabel(f"⚙️  Process List  —  {self._connection_name}")
        title.setObjectName("structureTitle")
        f = title.font()
        f.setBold(True)
        f.setPointSize(12)
        title.setFont(f)

        self._auto_cb = QCheckBox("Auto-refresh (5s)")
        self._auto_cb.toggled.connect(self._toggle_auto_refresh)

        self._refresh_btn = QPushButton("🔄 Refresh")
        self._refresh_btn.setFixedWidth(90)
        self._refresh_btn.clicked.connect(self._refresh)

        self._kill_btn = QPushButton("🛑 Kill Process")
        self._kill_btn.setObjectName("deleteBtn")
        self._kill_btn.setEnabled(False)
        self._kill_btn.clicked.connect(self._kill_selected)

        hdr.addWidget(title)
        hdr.addStretch()
        hdr.addWidget(self._auto_cb)
        hdr.addWidget(self._refresh_btn)
        hdr.addWidget(self._kill_btn)
        root.addLayout(hdr)

        # Process table
        self._table = QTableWidget(0, 0)
        self._table.setAlternatingRowColors(True)
        self._table.setSelectionBehavior(QTableWidget.SelectionBehavior.SelectRows)
        self._table.setEditTriggers(QTableWidget.EditTrigger.NoEditTriggers)
        self._table.horizontalHeader().setSectionResizeMode(
            QHeaderView.ResizeMode.ResizeToContents
        )
        self._table.horizontalHeader().setStretchLastSection(True)
        self._table.verticalHeader().setDefaultSectionSize(24)
        self._table.verticalHeader().setVisible(False)
        self._table.itemSelectionChanged.connect(self._on_selection_changed)
        root.addWidget(self._table)

    # ── Data loading ──────────────────────────────────────────────────────────

    def _refresh(self):
        self._refresh_btn.setEnabled(False)
        w = SchemaWorker(self._driver.get_process_list, parent=self)
        w.result.connect(self._populate)
        w.error.connect(self._on_error)
        w.finished.connect(lambda: self._refresh_btn.setEnabled(True))
        w.start()

    def _populate(self, data):
        cols, rows = data
        self._table.setColumnCount(len(cols))
        self._table.setHorizontalHeaderLabels([c.upper() for c in cols])
        self._table.setRowCount(0)
        for row in rows:
            r = self._table.rowCount()
            self._table.insertRow(r)
            for c, val in enumerate(row):
                item = QTableWidgetItem("" if val is None else str(val))
                item.setTextAlignment(
                    Qt.AlignmentFlag.AlignVCenter | Qt.AlignmentFlag.AlignLeft
                )
                self._table.setItem(r, c, item)
        self.status_message.emit(
            f"Process list: {len(rows)} process(es)"
        )

    def _on_error(self, msg: str):
        self._table.setRowCount(1)
        self._table.setColumnCount(1)
        self._table.setHorizontalHeaderLabels(["Error"])
        self._table.setItem(0, 0, QTableWidgetItem(msg))
        self.status_message.emit(f"Process list error: {msg}")

    # ── Kill ──────────────────────────────────────────────────────────────────

    def _on_selection_changed(self):
        self._kill_btn.setEnabled(bool(self._table.selectedItems()))

    def _kill_selected(self):
        row = self._table.currentRow()
        if row < 0:
            return

        # Process ID is always the first column
        pid_item = self._table.item(row, 0)
        if not pid_item or not pid_item.text():
            return

        try:
            pid = int(pid_item.text())
        except ValueError:
            self.status_message.emit("Could not determine process ID.")
            return

        btn = QMessageBox.warning(
            self, "Kill Process",
            f"Kill process {pid}?\n\nThis will immediately terminate the running query.",
            QMessageBox.StandardButton.Yes | QMessageBox.StandardButton.No,
            QMessageBox.StandardButton.No,
        )
        if btn != QMessageBox.StandardButton.Yes:
            return

        w = SchemaWorker(self._driver.kill_process, pid, parent=self)
        w.result.connect(lambda _: (
            self.status_message.emit(f"Process {pid} killed."),
            self._refresh(),
        ))
        w.error.connect(
            lambda e: QMessageBox.warning(self, "Kill Error",
                                          f"Could not kill process {pid}:\n{e}")
        )
        w.start()

    # ── Auto-refresh ──────────────────────────────────────────────────────────

    def _toggle_auto_refresh(self, checked: bool):
        if checked:
            self._refresh_timer.start(5000)
        else:
            self._refresh_timer.stop()

    def closeEvent(self, event):
        self._refresh_timer.stop()
        super().closeEvent(event)