import argparse
import ast
import csv
import os
import re
import sys
import time

os.environ.setdefault("MPLCONFIGDIR", "/tmp/matplotlib")

import matplotlib.pyplot as plt
import numpy as np
import serial

from pc_reader import PACKET_SIZE, SYNC, decode_packet


TEXT_LINE_RE = re.compile(
    r"#?\s*(?P<count>\d+)\s+"
    r"(?P<freq>[-+]?\d+(?:\.\d+)?)Hz\s+"
    r"DIN=(?P<din>\[[^\]]+\])\s+"
    r"DOUT=(?P<dout>\[[^\]]+\])\s+"
    r"ACC=(?P<acc>\[[^\]]+\])\s+"
    r"GYRO=(?P<gyro>\[[^\]]+\])\s+"
    r"ANGLE=(?P<angle>\[[^\]]+\])"
)


FIELD_NAMES = (
    "acc_x_g",
    "acc_y_g",
    "acc_z_g",
    "gyro_x_dps",
    "gyro_y_dps",
    "gyro_z_dps",
    "angle_x_deg",
    "angle_y_deg",
    "angle_z_deg",
    "temp_c",
    "freq_hz",
)


def read_serial_samples(port, baud, seconds=None, max_samples=None, max_gap_ms=1000):
    samples = []
    buffer = bytearray()
    last_t_ms = None
    elapsed_s = 0.0
    bad_delta_count = 0
    start = time.monotonic()

    with serial.Serial(port, baud, timeout=1) as ser:
        print("Reading {} at {} baud...".format(port, baud), file=sys.stderr)

        while True:
            if seconds is not None and time.monotonic() - start >= seconds:
                break
            if max_samples is not None and len(samples) >= max_samples:
                break

            chunk = ser.read(ser.in_waiting or 1)
            if chunk:
                buffer.extend(chunk)

            while len(buffer) >= PACKET_SIZE:
                sync_index = buffer.find(SYNC)
                if sync_index < 0:
                    del buffer[:-1]
                    break
                if sync_index:
                    del buffer[:sync_index]
                if len(buffer) < PACKET_SIZE:
                    break

                packet = bytes(buffer[:PACKET_SIZE])
                if (sum(packet[:-1]) & 0xFF) != packet[-1]:
                    del buffer[0]
                    continue

                del buffer[:PACKET_SIZE]
                data = decode_packet(packet)

                if last_t_ms is None:
                    freq_hz = 0.0
                else:
                    delta = (data["t_ms"] - last_t_ms) & 0xFFFFFFFF
                    if 0 < delta <= max_gap_ms:
                        elapsed_s += delta / 1000.0
                        freq_hz = 1000.0 / delta
                    else:
                        bad_delta_count += 1
                        freq_hz = 0.0

                last_t_ms = data["t_ms"]
                samples.append(flatten_packet(data, elapsed_s, freq_hz))

                if max_samples is not None and len(samples) >= max_samples:
                    break

    if bad_delta_count:
        print(
            "Ignored {} abnormal packet time delta(s).".format(bad_delta_count),
            file=sys.stderr,
        )

    return samples


def flatten_packet(data, t_s, freq_hz):
    return {
        "t_s": t_s,
        "acc_x_g": data["acc_g"][0],
        "acc_y_g": data["acc_g"][1],
        "acc_z_g": data["acc_g"][2],
        "gyro_x_dps": data["gyro_dps"][0],
        "gyro_y_dps": data["gyro_dps"][1],
        "gyro_z_dps": data["gyro_dps"][2],
        "angle_x_deg": data["angle_deg"][0],
        "angle_y_deg": data["angle_deg"][1],
        "angle_z_deg": data["angle_deg"][2],
        "temp_c": data["temp_c"],
        "freq_hz": freq_hz,
        "din0": data["din"][0],
        "din1": data["din"][1],
        "din2": data["din"][2],
        "din3": data["din"][3],
        "dout0": data["dout"][0],
        "dout1": data["dout"][1],
    }


def read_text_log(path):
    samples = []
    t_s = 0.0

    with open(path, "r", encoding="utf-8") as f:
        for line in f:
            match = TEXT_LINE_RE.search(line)
            if not match:
                continue

            freq_hz = float(match.group("freq"))
            din = ast.literal_eval(match.group("din"))
            dout = ast.literal_eval(match.group("dout"))
            acc = ast.literal_eval(match.group("acc"))
            gyro = ast.literal_eval(match.group("gyro"))
            angle = ast.literal_eval(match.group("angle"))

            if samples and freq_hz > 0:
                t_s += 1.0 / freq_hz

            samples.append(
                {
                    "t_s": t_s,
                    "acc_x_g": acc[0],
                    "acc_y_g": acc[1],
                    "acc_z_g": acc[2],
                    "gyro_x_dps": gyro[0],
                    "gyro_y_dps": gyro[1],
                    "gyro_z_dps": gyro[2],
                    "angle_x_deg": angle[0],
                    "angle_y_deg": angle[1],
                    "angle_z_deg": angle[2],
                    "temp_c": np.nan,
                    "freq_hz": freq_hz,
                    "din0": din[0],
                    "din1": din[1],
                    "din2": din[2],
                    "din3": din[3],
                    "dout0": dout[0],
                    "dout1": dout[1],
                }
            )

    return samples


def write_csv(samples, path):
    if not samples:
        return

    columns = list(samples[0].keys())
    with open(path, "w", newline="", encoding="utf-8") as f:
        writer = csv.DictWriter(f, fieldnames=columns)
        writer.writeheader()
        writer.writerows(samples)


def print_stats(samples):
    if not samples:
        print("No samples parsed.")
        return

    print("Samples: {}".format(len(samples)))
    print("Duration: {:.3f}s".format(samples[-1]["t_s"] - samples[0]["t_s"]))

    for group_name, fields in (
        ("ACC g", ("acc_x_g", "acc_y_g", "acc_z_g")),
        ("GYRO dps", ("gyro_x_dps", "gyro_y_dps", "gyro_z_dps")),
        ("ANGLE deg", ("angle_x_deg", "angle_y_deg", "angle_z_deg")),
    ):
        print("\n{}".format(group_name))
        for field in fields:
            values = np.array([sample[field] for sample in samples], dtype=float)
            diffs = np.diff(values)
            diff_std = float(np.std(diffs)) if len(diffs) else 0.0
            print(
                "  {:12s} mean={: .6f} std={:.6f} ptp={:.6f} diff_std={:.6f}".format(
                    field,
                    float(np.mean(values)),
                    float(np.std(values)),
                    float(np.ptp(values)),
                    diff_std,
                )
            )

    freq = np.array([sample["freq_hz"] for sample in samples[1:]], dtype=float)
    if len(freq):
        print(
            "\nFrequency Hz mean={:.3f} std={:.3f} min={:.3f} max={:.3f}".format(
                float(np.mean(freq)),
                float(np.std(freq)),
                float(np.min(freq)),
                float(np.max(freq)),
            )
        )


def plot_samples(samples, output=None, show=True):
    if not samples:
        raise ValueError("No samples to plot.")

    t = np.array([sample["t_s"] for sample in samples], dtype=float)
    fig, axes = plt.subplots(4, 1, sharex=True, figsize=(13, 9))

    plot_group(
        axes[0],
        t,
        samples,
        ("acc_x_g", "acc_y_g", "acc_z_g"),
        "Acceleration (g)",
    )
    plot_group(
        axes[1],
        t,
        samples,
        ("gyro_x_dps", "gyro_y_dps", "gyro_z_dps"),
        "Gyro (deg/s)",
    )
    plot_group(
        axes[2],
        t,
        samples,
        ("angle_x_deg", "angle_y_deg", "angle_z_deg"),
        "Angle (deg)",
    )

    freq = np.array([sample["freq_hz"] for sample in samples], dtype=float)
    axes[3].plot(t, freq, label="freq_hz", color="tab:purple", linewidth=1.0)
    axes[3].set_ylabel("Hz")
    axes[3].set_xlabel("Time (s)")
    axes[3].grid(True, alpha=0.3)
    axes[3].legend(loc="upper right")

    fig.suptitle("IMU Data Quality Overview")
    fig.tight_layout()

    if output:
        fig.savefig(output, dpi=160)
        print("Saved plot to {}".format(output))

    if show:
        plt.show()


def plot_group(axis, t, samples, fields, ylabel):
    for field in fields:
        values = np.array([sample[field] for sample in samples], dtype=float)
        axis.plot(t, values, label=field, linewidth=1.0)
    axis.set_ylabel(ylabel)
    axis.grid(True, alpha=0.3)
    axis.legend(loc="upper right", ncol=3)


def main():
    parser = argparse.ArgumentParser(
        description="Read ESP IMU data and visualise signal quality/noise."
    )
    source = parser.add_mutually_exclusive_group(required=True)
    source.add_argument("--file", help="pc_reader text log, for example rcd.txt")
    source.add_argument("--port", help="ESP32 serial port, for example /dev/ttyUSB0")
    parser.add_argument("--baud", type=int, default=115200)
    parser.add_argument("--seconds", type=float, default=10.0)
    parser.add_argument("--samples", type=int)
    parser.add_argument(
        "--max-gap-ms",
        type=int,
        default=1000,
        help="Ignore packet timestamp jumps larger than this.",
    )
    parser.add_argument("--output", default="imu_quality.png")
    parser.add_argument("--csv", help="Optional CSV export path.")
    parser.add_argument("--no-show", action="store_true", help="Save only; do not open a window.")
    args = parser.parse_args()

    if args.file:
        samples = read_text_log(args.file)
    else:
        samples = read_serial_samples(
            args.port,
            args.baud,
            args.seconds,
            args.samples,
            args.max_gap_ms,
        )

    print_stats(samples)

    if args.csv:
        write_csv(samples, args.csv)
        print("Saved CSV to {}".format(args.csv))

    plot_samples(samples, output=args.output, show=not args.no_show)


if __name__ == "__main__":
    main()