import numpy as np
from fastapi import HTTPException
from scipy import signal

from .config import BODE_MAX_MULTIPLIER, BODE_POINTS
from .schemas import BodeCascadeParams, BodeCompareParams, BodeParams
from .validation import require_finite, validate_coefficients


def _bode_series(b_values, a_values, f_eval, fs_val):
    b_vals = validate_coefficients(b_values, "b")
    a_vals = validate_coefficients(a_values, "a")
    _, h = signal.freqz(b_vals, a_vals, worN=f_eval, fs=fs_val)
    return {
        "mag": (20 * np.log10(np.abs(h) + 1e-12)).tolist(),
        "phase": np.angle(h, deg=True).tolist(),
    }


def _frequency_axis(fs):
    fs_val = require_finite(fs, "fs")
    f_min = fs_val / 50000.0
    f_max = fs_val * BODE_MAX_MULTIPLIER
    return fs_val, np.logspace(np.log10(f_min), np.log10(f_max), BODE_POINTS)


def calculate_bode_response(params: BodeParams):
    fs_val, f_eval = _frequency_axis(params.fs)
    series = _bode_series(params.b, params.a, f_eval, fs_val)
    return {
        "freq": f_eval.tolist(),
        "mag": series["mag"],
        "phase": series["phase"],
    }


def calculate_bode_compare_response(params: BodeCompareParams):
    fs_val, f_eval = _frequency_axis(params.ideal.fs)
    fixed_fs_val = require_finite(params.fixed.fs, "fixed.fs")
    if not np.isclose(fixed_fs_val, fs_val):
        raise HTTPException(status_code=400, detail="ideal 與 fixed 的 fs 必須相同")

    ideal = _bode_series(params.ideal.b, params.ideal.a, f_eval, fs_val)
    fixed = _bode_series(params.fixed.b, params.fixed.a, f_eval, fs_val)
    return {
        "freq": f_eval.tolist(),
        "ideal": ideal,
        "fixed": fixed,
    }


def calculate_bode_cascade_response(params: BodeCascadeParams):
    fs_val, f_eval = _frequency_axis(params.fs)
    h_total_ideal = np.ones(len(f_eval), dtype=complex)
    h_total_fixed = np.ones(len(f_eval), dtype=complex)
    any_active = False

    for i, stage in enumerate(params.stages):
        if not stage.isActive:
            continue
        any_active = True
        b_vals = validate_coefficients(stage.b, f"stages[{i}].b")
        a_vals = validate_coefficients(stage.a, f"stages[{i}].a")
        b_fixed_vals = validate_coefficients(stage.b_fixed, f"stages[{i}].b_fixed")
        a_fixed_vals = validate_coefficients(stage.a_fixed, f"stages[{i}].a_fixed")
        _, h_ideal = signal.freqz(b_vals, a_vals, worN=f_eval, fs=fs_val)
        _, h_fixed = signal.freqz(b_fixed_vals, a_fixed_vals, worN=f_eval, fs=fs_val)
        h_total_ideal *= h_ideal
        h_total_fixed *= h_fixed

    if not any_active:
        h_total_ideal = np.ones(len(f_eval), dtype=complex)
        h_total_fixed = np.ones(len(f_eval), dtype=complex)

    return {
        "freq": f_eval.tolist(),
        "ideal": {
            "mag": (20 * np.log10(np.abs(h_total_ideal) + 1e-12)).tolist(),
            "phase": np.angle(h_total_ideal, deg=True).tolist(),
        },
        "fixed": {
            "mag": (20 * np.log10(np.abs(h_total_fixed) + 1e-12)).tolist(),
            "phase": np.angle(h_total_fixed, deg=True).tolist(),
        },
    }