"""Sessions panel widget for the TUI."""

from __future__ import annotations

from textual.app import ComposeResult
from textual.containers import Vertical
from textual.widgets import DataTable, Static
from textual.widgets.data_table import RowKey

from clients.terminal.tui.events import SessionListUpdated, SessionSelected, SessionInfo


class SessionsPanel(Vertical):
    """Right-side panel showing server sessions and allowing quick switching."""

    DEFAULT_CSS = """
    SessionsPanel {
        border: solid $tui-panel;
        background: $tui-panel;
        color: $tui-text-muted;
        padding: 0;
        height: 1fr;
        width: 1fr;
    }
    SessionsPanel .title {
        text-style: bold;
        color: $tui-primary;
        padding: 1 1 0 1;
        height: auto;
    }
    SessionsPanel DataTable {
        height: 1fr;
        border: none;
        background: $tui-panel;
        color: $tui-text-muted;
    }
    SessionsPanel DataTable > .datatable--header {
        color: $tui-text-dim;
        text-style: bold;
        background: $tui-surface;
    }
    SessionsPanel DataTable > .datatable--row {
        background: $tui-panel;
    }
    SessionsPanel DataTable > .datatable--row-sessions-panel-cursor {
        background: $tui-selection;
        color: $tui-background;
    }
    SessionsPanel DataTable > .datatable--row-sessions-panel-cursor .datatable--cursor {
        color: $tui-background;
    }
    SessionsPanel .empty {
        color: $tui-text-dim;
        text-align: center;
        padding: 1;
    }
    """

    def __init__(self) -> None:
        super().__init__()
        self._title = Static("Sessions", classes="title")
        self._table: DataTable | None = None
        self._sessions: list[SessionInfo] = []
        self._current_id: str | None = None

    def compose(self) -> ComposeResult:
        yield self._title
        yield DataTable(id="sessions-table")

    def on_mount(self) -> None:
        self._table = self.query_one("#sessions-table", DataTable)
        self._table.cursor_type = "row"
        self._table.show_header = True
        self._table.zebra_stripes = True
        self._table.add_columns("", "ID", "Profile", "Preview")
        self._populate_table()

    def on_session_list_updated(self, event: SessionListUpdated) -> None:
        self._sessions = event.sessions
        self._current_id = event.current_id
        self._populate_table()

    def _populate_table(self) -> None:
        if self._table is None:
            return
        self._table.clear()
        if not self._sessions:
            self._table.add_row("", "—", "", "No sessions")
            return

        for session in self._sessions:
            marker = "●" if session.id == self._current_id else ""
            short_id = "-".join(session.id.split("-")[:2])
            profile = self._truncate(session.profile_id, 12)
            preview = self._truncate(session.title, 24)
            self._table.add_row(marker, short_id, profile, preview, key=session.id)

        if self._current_id:
            try:
                self._table.move_cursor(row=RowKey(self._current_id))
            except Exception:
                pass

    def on_data_table_row_selected(self, event: DataTable.RowSelected) -> None:
        session_id = str(event.row_key.value) if event.row_key else ""
        if session_id:
            self.post_message(SessionSelected(session_id))

    def on_key(self, event) -> None:
        if self._table is None:
            return
        if hasattr(event, "key") and event.key in ("enter", "return"):
            cursor = self._table.cursor_coordinate
            if cursor:
                row_key = self._table.get_row_at(cursor.row)
                session_id = str(row_key) if row_key else ""
                if session_id:
                    self.post_message(SessionSelected(session_id))
            event.stop()
            event.prevent_default()

    @staticmethod
    def _truncate(text: str, max_len: int) -> str:
        if len(text) <= max_len:
            return text
        return text[: max_len - 1] + "…"