from __future__ import annotations

import html
from datetime import datetime, timezone
from typing import Iterable, List

from .boinc import BoincSnapshot, Task


def progress_bar(percent: float, width: int = 16) -> str:
    clamped = max(0, min(percent, 100))
    filled = int(round((clamped / 100.0) * width))
    return "[" + "#" * filled + "." * (width - filled) + "]"


def humanize_seconds(seconds: float) -> str:
    if seconds <= 0:
        return "0s"
    minutes, sec = divmod(int(seconds), 60)
    hours, minutes = divmod(minutes, 60)
    days, hours = divmod(hours, 24)
    parts = []
    if days:
        parts.append(f"{days}d")
    if hours:
        parts.append(f"{hours}h")
    if minutes:
        parts.append(f"{minutes}m")
    if sec and len(parts) < 2:
        parts.append(f"{sec}s")
    return " ".join(parts) if parts else f"{sec}s"


def format_timestamp(dt: datetime) -> str:
    if not dt:
        return "-"
    if not dt.tzinfo:
        dt = dt.replace(tzinfo=timezone.utc)
    return dt.astimezone(timezone.utc).strftime("%Y-%m-%d %H:%M UTC")


def format_task(task: Task) -> str:
    safe_name = html.escape(task.name)
    safe_project = html.escape(task.project)
    eta = humanize_seconds(task.remaining_seconds or 0)
    deadline = format_timestamp(task.deadline) if task.deadline else "-"
    bar = progress_bar(task.progress_percent)
    return (
        f"<b>{safe_name}</b> ({safe_project})\n"
        f"{bar} {task.progress_percent}% | ETA {eta} | Deadline {deadline}"
    )


def format_tasks_section(title: str, tasks: Iterable[Task]) -> str:
    items = list(tasks)
    if not items:
        return f"<b>{html.escape(title)}:</b> ничего нет"
    lines: List[str] = [f"<b>{html.escape(title)}:</b>"]
    for task in items:
        lines.append(format_task(task))
    return "\n".join(lines)


def format_dashboard(snapshot: BoincSnapshot) -> str:
    lines = [
        "<b>BOINC / grcpool монитор</b>",
        f"Обновлено: {format_timestamp(snapshot.fetched_at)}",
        "",
        f"Активные: {len(snapshot.active)} | В очереди: {len(snapshot.queued)} | Завершены: {len(snapshot.completed)}",
        f"Средний прогресс: {snapshot.average_progress:.1f}% | Оставшееся время: {humanize_seconds(snapshot.total_remaining_seconds)}",
        "",
        format_tasks_section("Активные задачи", snapshot.active[:5]),
    ]

    if snapshot.queued:
        lines.extend(["", format_tasks_section("Ожидают запуска", snapshot.queued[:5])])
    if snapshot.completed:
        lines.extend(["", format_tasks_section("Готовы к отправке", snapshot.completed[:5])])

    return "\n".join(lines)