from __future__ import annotations

import curses
from typing import Optional

from .colors import UIColors


class HeaderView:
    """Top panel with live metrics."""

    def __init__(self, height: int, width: int, y: int, x: int) -> None:
        self.win = curses.newwin(height, width, y, x)

    def render(
        self,
        iteration: int,
        digits: int,
        elapsed: float,
        rate: float,
        last_digit: Optional[str],
        computing: bool,
    ) -> None:
        self.win.erase()
        style = UIColors.style(UIColors.HEADER, bold=True)
        metric_style = UIColors.style(UIColors.METRIC, bold=True)
        status_style = UIColors.style(UIColors.STATUS)

        lines = [
            " π Stream Dashboard ",
            f" Iteration: {iteration:,}",
            f" Digits: {digits:,}",
            f" Elapsed: {elapsed:8.2f}s • Rate: {rate:8.2f} digits/s",
        ]
        status = " Generating…" if computing else " Idle"
        digit_line = f" Last digit: {last_digit if last_digit is not None else '—'}"

        try:
            self.win.addstr(0, 0, lines[0], style)
            self.win.addstr(1, 0, lines[1], metric_style)
            self.win.addstr(2, 0, lines[2], metric_style)
            self.win.addstr(3, 0, lines[3], metric_style)
            self.win.addstr(4, 0, digit_line, metric_style)
            self.win.addstr(5, 0, status, status_style)
            width = max(1, self.win.getmaxyx()[1] - 1)
            self.win.addstr(6, 0, "─" * width, UIColors.style(UIColors.SEPARATOR))
        except curses.error:
            pass

        self.win.noutrefresh()


class DigitsView:
    """Scrollable window for the π digits."""

    def __init__(self, height: int, width: int, y: int, x: int) -> None:
        self.win = curses.newwin(height, width, y, x)

    def render(self, digits_text: str, scroll: int) -> int:
        self.win.erase()
        max_y, max_x = self.win.getmaxyx()
        if max_y <= 0 or max_x <= 0:
            self.win.noutrefresh()
            return 0

        cols = max(1, max_x - 1)
        chunks = [digits_text[i : i + cols] for i in range(0, len(digits_text), cols)] or ["0"]

        max_scroll = max(0, len(chunks) - max_y)
        scroll = max(0, min(scroll, max_scroll))
        style = UIColors.style(UIColors.NUMBER)

        for idx, chunk in enumerate(chunks[scroll : scroll + max_y]):
            try:
                self.win.addstr(idx, 0, chunk, style)
            except curses.error:
                break

        self.win.noutrefresh()
        return scroll


class HelpView:
    """Bottom row with key hints."""

    def __init__(self, y: int, x: int, width: int) -> None:
        self.win = curses.newwin(1, width, y, x)

    def render(self) -> None:
        message = " ↑↓ scroll  •  q quit"
        try:
            self.win.addstr(0, 0, message, UIColors.style(UIColors.STATUS, dim=True))
        except curses.error:
            pass
        self.win.noutrefresh()