from __future__ import annotations

import csv
from pathlib import Path
from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from app.core.antenna import AntennaPattern


def _parse_float(value: str) -> float:
    return float(value.strip())


def load_pattern_file(path: str | Path) -> list[tuple[float, float, float]]:
    file_path = Path(path)
    if not file_path.exists():
        raise FileNotFoundError(f"Antenna pattern file not found: {file_path}")

    samples: list[tuple[float, float, float]] = []
    with file_path.open(encoding="utf-8", newline="") as handle:
        reader = csv.reader(handle)
        for row in reader:
            if not row or row[0].startswith("#"):
                continue
            if len(row) < 3:
                continue
            if row[0].lower() in {"azimuth_deg", "az", "azimuth"}:
                continue
            samples.append((_parse_float(row[0]), _parse_float(row[1]), _parse_float(row[2])))

    if not samples:
        raise ValueError(f"No antenna pattern samples found in {file_path}")
    return samples


def gain_from_file(
    pattern: AntennaPattern,
    az_deg: float,
    el_deg: float,
) -> float:
    if not pattern.pattern_file:
        raise ValueError("pattern_file is required for file patterns")

    samples = load_pattern_file(pattern.pattern_file)
    nearest = min(
        samples,
        key=lambda item: abs(item[0] - az_deg) + abs(item[1] - el_deg),
    )
    return pattern.gain_dbi + nearest[2]