"""
Progress reporting for long-running calculations.
"""

import time
from typing import Optional, Callable, Awaitable


class ProgressTracker:
    """Track and report calculation progress."""

    def __init__(
        self,
        total: int,
        callback: Optional[Callable[[str, float, Optional[float]], Awaitable[None]]] = None,
        phase: str = "calculating",
    ):
        self.total = total
        self.callback = callback
        self.phase = phase
        self.completed = 0
        self.start_time = time.time()

    @property
    def progress(self) -> float:
        if self.total == 0:
            return 1.0
        return self.completed / self.total

    @property
    def eta_seconds(self) -> Optional[float]:
        if self.completed == 0:
            return None
        elapsed = time.time() - self.start_time
        rate = self.completed / elapsed
        remaining = self.total - self.completed
        return remaining / rate if rate > 0 else None

    def update(self, n: int = 1):
        self.completed += n

    async def report(self):
        if self.callback:
            await self.callback(self.phase, self.progress, self.eta_seconds)