"""Cost tracking — monitor token usage and enforce budget limits."""

from __future__ import annotations

import time
from dataclasses import dataclass, field
from pathlib import Path

import aiosqlite
from loguru import logger


# Pricing per 1M tokens (input, output) in USD
MODEL_PRICING: dict[str, tuple[float, float]] = {
    # Anthropic
    "claude-sonnet-4-5-20250929": (3.0, 15.0),
    "claude-haiku-4-5-20251001": (0.80, 4.0),
    "claude-opus-4-6": (15.0, 75.0),
    # NVIDIA NIM / LiteLLM
    "nvidia_nim/deepseek-ai/deepseek-v3.1": (0.27, 1.10),
    "nvidia_nim/moonshotai/kimi-k2.5": (0.35, 1.40),
    "nvidia_nim/minimaxai/minimax-m2.1": (0.30, 1.10),
    # Fallback
    "_default": (1.0, 3.0),
}


def _get_pricing(model: str) -> tuple[float, float]:
    """Get (input_price, output_price) per 1M tokens for a model."""
    return MODEL_PRICING.get(model, MODEL_PRICING["_default"])


@dataclass
class CostRecord:
    model: str
    input_tokens: int
    output_tokens: int
    cost_usd: float
    timestamp: float


@dataclass
class BudgetConfig:
    daily_limit_usd: float = 0.0  # 0 = no limit
    monthly_limit_usd: float = 0.0  # 0 = no limit
    warning_threshold: float = 0.8  # warn at 80% of budget


class CostTracker:
    """Track LLM costs in SQLite and enforce budget limits."""

    def __init__(
        self,
        db_path: str | Path = "data/costs.db",
        budget: BudgetConfig | None = None,
    ) -> None:
        self._db_path = str(db_path)
        self._budget = budget or BudgetConfig()
        self._db: aiosqlite.Connection | None = None

    async def setup(self) -> None:
        Path(self._db_path).parent.mkdir(parents=True, exist_ok=True)
        self._db = await aiosqlite.connect(self._db_path)
        await self._db.execute("PRAGMA journal_mode=WAL")
        await self._db.execute(
            """
            CREATE TABLE IF NOT EXISTS cost_records (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                model TEXT NOT NULL,
                input_tokens INTEGER NOT NULL,
                output_tokens INTEGER NOT NULL,
                cost_usd REAL NOT NULL,
                timestamp REAL NOT NULL
            )
            """
        )
        await self._db.commit()

    async def close(self) -> None:
        if self._db:
            await self._db.close()
            self._db = None

    async def record(self, model: str, usage: dict[str, int]) -> CostRecord:
        """Record token usage and return the cost record."""
        input_tokens = usage.get("input_tokens", 0)
        output_tokens = usage.get("output_tokens", 0)
        input_price, output_price = _get_pricing(model)
        cost = (input_tokens * input_price + output_tokens * output_price) / 1_000_000

        record = CostRecord(
            model=model,
            input_tokens=input_tokens,
            output_tokens=output_tokens,
            cost_usd=cost,
            timestamp=time.time(),
        )

        if self._db:
            await self._db.execute(
                "INSERT INTO cost_records (model, input_tokens, output_tokens, cost_usd, timestamp) VALUES (?, ?, ?, ?, ?)",
                (model, input_tokens, output_tokens, cost, record.timestamp),
            )
            await self._db.commit()

        logger.debug(
            f"Cost: {model} — {input_tokens}in/{output_tokens}out = ${cost:.6f}"
        )
        return record

    async def check_budget(self) -> str:
        """Check budget status. Returns 'ok', 'warning', or 'exceeded'."""
        if not self._db:
            return "ok"

        now = time.time()

        # Daily check
        if self._budget.daily_limit_usd > 0:
            day_start = now - (now % 86400)
            daily_total = await self._sum_costs_since(day_start)
            if daily_total >= self._budget.daily_limit_usd:
                logger.warning(f"Daily budget EXCEEDED: ${daily_total:.4f} / ${self._budget.daily_limit_usd:.2f}")
                return "exceeded"
            if daily_total >= self._budget.daily_limit_usd * self._budget.warning_threshold:
                logger.warning(f"Daily budget warning: ${daily_total:.4f} / ${self._budget.daily_limit_usd:.2f}")
                return "warning"

        # Monthly check
        if self._budget.monthly_limit_usd > 0:
            month_start = now - (now % (86400 * 30))
            monthly_total = await self._sum_costs_since(month_start)
            if monthly_total >= self._budget.monthly_limit_usd:
                logger.warning(f"Monthly budget EXCEEDED: ${monthly_total:.4f} / ${self._budget.monthly_limit_usd:.2f}")
                return "exceeded"
            if monthly_total >= self._budget.monthly_limit_usd * self._budget.warning_threshold:
                logger.warning(f"Monthly budget warning: ${monthly_total:.4f} / ${self._budget.monthly_limit_usd:.2f}")
                return "warning"

        return "ok"

    async def get_summary(self) -> dict:
        """Get a cost summary with per-model breakdown."""
        if not self._db:
            return {"total_usd": 0, "models": {}}

        now = time.time()
        day_start = now - (now % 86400)

        rows: list = []
        async with self._db.execute(
            "SELECT model, SUM(input_tokens), SUM(output_tokens), SUM(cost_usd) FROM cost_records WHERE timestamp >= ? GROUP BY model",
            (day_start,),
        ) as cursor:
            rows = await cursor.fetchall()

        models = {}
        total = 0.0
        for model, inp, out, cost in rows:
            models[model] = {"input_tokens": inp, "output_tokens": out, "cost_usd": cost}
            total += cost

        return {"total_usd": total, "models": models}

    async def _sum_costs_since(self, since: float) -> float:
        if not self._db:
            return 0.0
        async with self._db.execute(
            "SELECT COALESCE(SUM(cost_usd), 0) FROM cost_records WHERE timestamp >= ?",
            (since,),
        ) as cursor:
            row = await cursor.fetchone()
        return row[0] if row else 0.0