"""Analytics API router -- dashboard metrics endpoint."""

from __future__ import annotations

import re
from dataclasses import asdict
from typing import TYPE_CHECKING, Any

from fastapi import APIRouter, HTTPException, Query, Request

from app.analytics.queries import get_analytics

if TYPE_CHECKING:
    from psycopg_pool import AsyncConnectionPool

router = APIRouter(prefix="/api/analytics", tags=["analytics"])

_RANGE_PATTERN = re.compile(r"^(\d+)d$")
_DEFAULT_RANGE = "7d"
_MAX_RANGE_DAYS = 365


async def _get_pool(request: Request) -> AsyncConnectionPool:
    """Dependency: extract the shared pool from app state."""
    return request.app.state.pool


def _envelope(data: Any, *, success: bool = True, error: str | None = None) -> dict:
    return {"success": success, "data": data, "error": error}


def _parse_range(range_str: str) -> int:
    """Parse 'Xd' range string to integer days. Raises 400 on invalid format."""
    match = _RANGE_PATTERN.match(range_str)
    if not match:
        raise HTTPException(
            status_code=400,
            detail="Invalid range format. Expected: '<N>d' e.g. '7d', '30d'.",
        )
    days = int(match.group(1))
    if days < 1 or days > _MAX_RANGE_DAYS:
        raise HTTPException(
            status_code=400,
            detail=f"Range must be between 1 and {_MAX_RANGE_DAYS} days.",
        )
    return days


@router.get("")
async def analytics(
    request: Request,
    range: str = Query(default=_DEFAULT_RANGE, alias="range"),  # noqa: A002
) -> dict:
    """Return aggregated analytics metrics for the given time range."""
    range_days = _parse_range(range)
    pool = await _get_pool(request)
    result = await get_analytics(pool, range_days=range_days)
    return _envelope(asdict(result))