"""
`meshbay-cli chat` with no group: the groups, then one group's chat, IRC-style.

The list shows every group of the account; Enter opens one whose node is up and
whose chat is on (`enabled_apps` in the sealed ack, empty meaning all). The room
shows the last messages, then the ones that arrive (`chat_msg` pushed by the
node), and a line at the bottom to write in. Esc, or `/part`, goes back to the
list; Ctrl+Q, or `/quit`, quits. A right-click copies — the text selected with
the mouse, else the line under the pointer — and pastes into the line written
in. Messages are read and posted exactly as the
`chat` action reads and posts them — signature, epoch key, content, then the
roster's verdict on the signing device — and drawn as text, never markup.
"""

import asyncio
import contextlib
import time

from rich.segment import Segment
from rich.text import Text
from textual import events
from textual.app import ComposeResult
from textual.binding import Binding
from textual.screen import Screen
from textual.selection import Selection
from textual.strip import Strip
from textual.widgets import DataTable, Footer, Input, RichLog, Static

from ..client.account import Account
from ..client.chat import Message, chat_keys, history, open_row, post
from ..client.groups import my_groups
from ..client.paths import handle
from ..client.pool import Pool
from ..client.roster import RosterCheck
from ..errors import CliError
from ..output import safe
from . import clipboard

# How much of the conversation a room opens on.
BACKLOG = 50
HELP = ("/part or Esc: back to the groups   /quit or Ctrl+Q: quit   "
        "right-click: copy, paste   /help: this")
# Under a message's first line, its next ones and what is said about it.
INDENT = " " * 6
KEY_CHANGED = ("! This account is using a key you have not seen before: a new device "
               "added elsewhere, or the node naming the wrong person.")


def chat_enabled(ack: dict) -> bool:
    apps = ack.get("enabled_apps") or []
    return not apps or "chat" in apps


class ChatGroupsScreen(Screen):
    BINDINGS = [
        Binding("r", "refresh", "Refresh"),
        Binding("q", "app.quit", "Quit"),
    ]

    DEFAULT_CSS = """
    ChatGroupsScreen > .title { height: 1; padding: 0 1; background: $panel; }
    ChatGroupsScreen > DataTable { height: 1fr; }
    """

    def __init__(self, account: Account):
        super().__init__()
        self.account = account
        self.pool = Pool(account)
        self.groups: list[dict] = []

    def compose(self) -> ComposeResult:
        yield Static(Text("Chat — choose a group, Enter to join"), classes="title")
        table = DataTable(cursor_type="row")
        table.add_column("Group", key="group")
        table.add_column("Node", key="node")
        yield table
        yield Footer()

    def on_mount(self) -> None:
        self.query_one(DataTable).focus()
        self.action_refresh()

    def action_refresh(self) -> None:
        self.run_worker(self._load(), exclusive=True, group="groups")

    async def _load(self) -> None:
        try:
            self.groups = sorted(await my_groups(self.account),
                                 key=lambda g: (g["name"].lower(), g.get("owner_username")))
        except CliError as e:
            self.app.notify(e.message, severity="error", markup=False)
            return
        table = self.query_one(DataTable)
        table.clear()
        for g in self.groups:
            up = g.get("node_online")
            table.add_row(Text(safe(handle(g)), style="" if up else "dim", no_wrap=True,
                               overflow="ellipsis"),
                          Text("up" if up else "down", style="" if up else "dim"),
                          key=g["id"])

    def on_data_table_row_selected(self, event: DataTable.RowSelected) -> None:
        group = next((g for g in self.groups if g["id"] == event.row_key.value), None)
        if group is not None:
            self.run_worker(self._join(group), exclusive=True, group="join")

    async def _join(self, group: dict) -> None:
        self.app.notify(f"Joining {safe(handle(group))}…", timeout=3, markup=False)
        try:
            session = await self.pool.session(group)
        except CliError as e:
            self.app.notify(e.message, severity="error", markup=False, timeout=8)
            return
        if not chat_enabled(session.ack):
            self.app.notify(f"{safe(handle(group))} has its chat turned off.",
                            severity="warning", markup=False)
            return
        await self.app.push_screen(ChatRoomScreen(self.account, group, session))

    async def on_unmount(self) -> None:
        with contextlib.suppress(Exception):
            await self.pool.close()


class ChatLog(RichLog):
    """The conversation, selectable with the mouse — RichLog alone is not."""

    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        # (first line, line after the last, its text) for each thing written.
        self._blocks: list[tuple[int, int, str]] = []

    def write(self, content, *args, **kwargs):
        # Writes before the size is known come back through here once it is.
        first = len(self.lines)
        result = super().write(content, *args, **kwargs)
        if len(self.lines) > first and isinstance(content, Text):
            self._blocks.append((first, len(self.lines),
                                 content.plain.replace("\n" + INDENT, "\n")))
        return result

    def text_at(self, y: int) -> str | None:
        return next((text for first, end, text in self._blocks if first <= y < end), None)

    def get_selection(self, selection: Selection) -> tuple[str, str] | None:
        text = "\n".join(line.text.rstrip() for line in self.lines)
        return selection.extract(text), "\n"

    def selection_updated(self, selection: Selection | None) -> None:
        self._line_cache.clear()
        self.refresh()

    def _render_line(self, y: int, scroll_x: int, width: int) -> Strip:
        line = super()._render_line(y, scroll_x, width)
        if y >= len(self.lines):
            return line
        selection = self.text_selection
        span = selection.get_span(y) if selection is not None else None
        if span is not None:
            start, end = span
            end = self.lines[y].cell_length if end == -1 else end
            start, end = max(start - scroll_x, 0), max(end - scroll_x, 0)
            style = self.screen.get_component_rich_style("screen--selection")
            line = Strip.join([
                line.crop(0, start),
                Strip(Segment.apply_style(list(line.crop(start, end)), post_style=style)),
                line.crop(end)])
        # Where each cell sits in the text: what the screen's selection reads.
        return line.apply_offsets(scroll_x, y)

    async def right_click(self, event: events.MouseDown) -> None:
        selection = self.text_selection
        text = self.get_selection(selection)[0] if selection is not None else ""
        if not text:
            y = event.screen_y - self.content_region.y + self.scroll_offset.y
            text = self.text_at(y) or ""
        if text:
            self.app.copy_to_clipboard(text)
            self.app.notify("Copied.", timeout=2)
            self.run_worker(clipboard.write_text(text), group="clipboard")


class ChatInput(Input):
    async def right_click(self, event: events.MouseDown) -> None:
        self.focus()
        self.run_worker(self._paste(), exclusive=True, group="clipboard")

    async def _paste(self) -> None:
        text = await clipboard.read_text()
        if text is None:
            text = self.app.clipboard
        # One line to write in: the lines of what is pasted, side by side.
        text = " ".join(part for part in text.splitlines() if part.strip())
        if not text:
            self.app.notify("Nothing to paste.", timeout=2)
            return
        self.replace(text, *self.selection)


class ChatRoomScreen(Screen):
    BINDINGS = [Binding("escape", "part", "Back to the groups")]

    DEFAULT_CSS = """
    ChatRoomScreen > .title { height: 1; padding: 0 1; background: $panel; }
    ChatRoomScreen > ChatLog { height: 1fr; padding: 0 1; }
    ChatRoomScreen > ChatInput { dock: bottom; }
    """

    def __init__(self, account: Account, group: dict, session):
        super().__init__()
        self.account = account
        self.group = group
        self.session = session
        self.keys = None
        self.check = RosterCheck(account, session)
        self._day = ""
        self._ready = asyncio.Event()

    def compose(self) -> ComposeResult:
        yield Static(Text(f"#{safe(handle(self.group))}   —   {HELP}", no_wrap=True,
                          overflow="ellipsis"), classes="title")
        yield ChatLog(wrap=True, markup=False, highlight=False, auto_scroll=True)
        yield ChatInput(placeholder=f"Message to {safe(handle(self.group))}",
                        select_on_focus=False)
        yield Footer()

    @property
    def log_view(self) -> ChatLog:
        return self.query_one(ChatLog)

    def on_mount(self) -> None:
        self.query_one(Input).focus()
        self.session.ch.on_push("chat_msg", self._pushed)
        self.session.ch.on_push("chat_epoch_ack", self._epoch_moved)
        self.run_worker(self._open(), group="room")

    def on_unmount(self) -> None:
        self.session.ch.off_push("chat_msg", self._pushed)
        self.session.ch.off_push("chat_epoch_ack", self._epoch_moved)

    async def _open(self) -> None:
        try:
            self.keys = await chat_keys(self.session)
            rows = await history(self.session, BACKLOG)
            for row in rows:
                self.show(await open_row(row, self.keys, self.group["id"], self.check))
        except CliError as e:
            self.note(f"! {e.message}")
            return
        finally:
            self._ready.set()
        if not rows:
            self.note("No message yet. Say something.")

    # ── Drawing ──────────────────────────────────────────────────────────────

    def note(self, text: str, style: str = "italic dim") -> None:
        self.log_view.write(Text(text, style=style))

    def show(self, m: Message) -> None:
        day = time.strftime("%Y-%m-%d", time.localtime(m.timestamp))
        if day != self._day:
            self._day = day
            self.note(f"— {day} —")
        line = Text(time.strftime("%H:%M ", time.localtime(m.timestamp)), style="dim")
        line.append(f"<{safe(m.sender)}> ", style="bold")
        if m.unreadable:
            line.append(f"[this message cannot be read: {m.unreadable}]", style="italic")
        else:
            line.append(("\n" + INDENT).join(safe(part) for part in m.text.split("\n")))
        self.log_view.write(line)
        if m.trust == "changed":
            self.note(INDENT + KEY_CHANGED, style="bold yellow")

    # ── What the node pushes ─────────────────────────────────────────────────

    def _pushed(self, msg: dict) -> None:
        self.run_worker(self._arrived(msg), group="arrivals")

    async def _arrived(self, msg: dict) -> None:
        await self._ready.wait()
        if self.keys is None:
            return
        # A message sealed under an epoch opened since the keys were fetched.
        if int(msg.get("epoch") or 0) not in self.keys.by_epoch:
            with contextlib.suppress(CliError):
                self.keys = await chat_keys(self.session)
        msg = {**msg, "timestamp": msg.get("timestamp") or time.time()}
        self.show(await open_row(msg, self.keys, self.group["id"], self.check))

    def _epoch_moved(self, msg: dict) -> None:
        """Somebody was removed: a new epoch, and the key to post under with it."""
        self.session.ack["chat_epoch"] = int(msg.get("epoch") or 0)
        self.run_worker(self._refetch_keys(), group="keys")

    async def _refetch_keys(self) -> None:
        with contextlib.suppress(CliError):
            self.keys = await chat_keys(self.session)

    # ── Writing ──────────────────────────────────────────────────────────────

    async def on_input_submitted(self, event: Input.Submitted) -> None:
        text = event.value.rstrip()
        event.input.value = ""
        if not text.strip():
            return
        command = text.strip().lower()
        if command in ("/part", "/leave"):
            self.action_part()
            return
        if command in ("/quit", "/exit"):
            self.app.exit()
            return
        if command == "/help":
            self.note(HELP)
            return
        if command.startswith("/") and not command.startswith("//"):
            self.note(f"Unknown command {safe(text.split()[0])}. {HELP}")
            return
        if command.startswith("//"):
            text = text.lstrip()[1:]          # "//x" posts "/x"
        await self._ready.wait()
        try:
            await post(self.session, self.keys, text, self.account.username)
        except CliError as e:
            self.note(f"! Not sent: {e.message}", style="bold red")
            return
        # The node relays to everybody else; this side shows its own at once.
        self.show(Message(0, time.time(), self.account.username, text, trust="pinned"))

    def action_part(self) -> None:
        self.app.pop_screen()