from __future__ import annotations

import math
from collections.abc import Sequence

from app.market.base import MarketData
from app.schemas import Candle


class FakeMarketData(MarketData):
    """In-memory market data for tests and offline demos."""

    def __init__(self, candles: Sequence[Candle] | None = None) -> None:
        self.candles: list[Candle] = list(candles or [])

    @classmethod
    def from_closes(cls, closes: Sequence[float]) -> FakeMarketData:
        candles = [
            Candle(
                ts=1_700_000_000_000 + i * 60_000,
                open=close,
                high=close,
                low=close,
                close=close,
                volume=1.0,
            )
            for i, close in enumerate(closes)
        ]
        return cls(candles)

    @classmethod
    def sine_wave(cls, n: int = 200, amplitude: float = 100.0, period: int = 20) -> FakeMarketData:
        base = 1000.0
        closes = [base + amplitude * math.sin(2 * math.pi * i / period) for i in range(n)]
        return cls.from_closes(closes)

    def append(self, candle: Candle) -> None:
        self.candles.append(candle)

    async def fetch_candles(self, symbol: str, timeframe: str, limit: int) -> list[Candle]:
        return self.candles[-limit:]

    async def fetch_price(self, symbol: str) -> float:
        if not self.candles:
            raise ValueError("no candles available")
        return self.candles[-1].close