"""Look at the tracking signal around the known barrier-opening time.

Loads one tracking DB whose opening time we know (from
2025_07_15_barrier_opening.csv) and plots a few candidate signals against
time, with a vertical line at the ground-truth opening:

    1. Y position of each detection (raw scatter)
    2. Sliding-window Y range  (max - min over a window)
    3. Sliding-window |y - roi_midline|  (mean distance from midline)

The hope is one of these has a clean step-change at t = opening_time
that's robustly detectable across ROIs.

Run:
    python explore_barrier_signal.py
Outputs:
    figures/barrier_signal_<machine>_<time>.png
"""

from __future__ import annotations

import sqlite3
from pathlib import Path

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd

from config import FIGURES, TRACKING_OUTPUT_DIR

# Ground-truth case: machine 076, session 16-03-10 → opening = 52 s.
DB_NAME = "2025-07-15_16-03-10_076e2825a7274661bd0697c42d6fa4c0__1920x1088@25fps-28q_merged_tracking.db"
KNOWN_OPENING_S = 52.0
WINDOW_S = 10.0  # sliding-window length for the derived signals


def load_roi(db_path: Path, roi: int) -> pd.DataFrame:
    """Read one ROI table; return DataFrame with t in seconds."""
    with sqlite3.connect(f"file:{db_path}?mode=ro", uri=True) as conn:
        df = pd.read_sql_query(f"SELECT t, x, y, w, h, id FROM ROI_{roi}", conn)
    df["t_s"] = df["t"] / 1000.0
    return df


def per_frame_distance(df: pd.DataFrame) -> pd.DataFrame:
    """For frames with exactly 2 detections, return (t_s, distance)."""
    g = df.groupby("t")
    n_per_frame = g.size()
    two_fly_t = n_per_frame[n_per_frame == 2].index
    sub = df[df["t"].isin(two_fly_t)].sort_values(["t", "id"])
    pairs = sub.groupby("t").agg(
        x1=("x", "first"), y1=("y", "first"),
        x2=("x", "last"),  y2=("y", "last"),
        t_s=("t_s", "first"),
    )
    pairs["dist_px"] = np.hypot(pairs["x1"] - pairs["x2"], pairs["y1"] - pairs["y2"])
    return pairs.reset_index(drop=True)


def sliding_signals(df: pd.DataFrame, dist: pd.DataFrame,
                    window_s: float, step_s: float = 1.0) -> pd.DataFrame:
    """Per-window summary signals."""
    if df.empty:
        return pd.DataFrame()
    midline = df["y"].median()
    t0, t1 = df["t_s"].min(), df["t_s"].max()
    rows = []
    for start in np.arange(t0, t1 - window_s, step_s):
        sub  = df  [(df  ["t_s"] >= start) & (df  ["t_s"] < start + window_s)]
        sub_d = dist[(dist["t_s"] >= start) & (dist["t_s"] < start + window_s)]
        if sub.empty:
            continue
        rows.append({
            "mid_t":      start + window_s / 2,
            "y_range":    sub["y"].max() - sub["y"].min(),
            "y_mid_dist": (sub["y"] - midline).abs().mean(),
            "min_dist":   sub_d["dist_px"].min() if not sub_d.empty else np.nan,
            "mean_dist":  sub_d["dist_px"].mean() if not sub_d.empty else np.nan,
        })
    return pd.DataFrame(rows)


def main() -> None:
    db = TRACKING_OUTPUT_DIR / DB_NAME
    if not db.exists():
        raise FileNotFoundError(db)

    fig, axes = plt.subplots(6, 3, figsize=(16, 22), sharex=True)
    # Zoom: only plot first 200 s — opening is < 90s in all known cases.
    XLIM = (0, 200)
    for roi in range(1, 7):
        df = load_roi(db, roi)
        dist = per_frame_distance(df)
        windowed = sliding_signals(df, dist, WINDOW_S)

        ax_raw, ax_dist, ax_min = axes[roi - 1]

        # 1) raw y-positions, zoomed on the early window
        ax_raw.scatter(df["t_s"], df["y"], s=0.5, alpha=0.4, c="steelblue")
        ax_raw.axvline(KNOWN_OPENING_S, color="red", lw=1, ls="--",
                       label=f"opening = {KNOWN_OPENING_S}s")
        ax_raw.set_ylabel(f"ROI {roi}\ny (px)")
        ax_raw.set_xlim(*XLIM)
        if roi == 1:
            ax_raw.set_title("Raw y(t)")
            ax_raw.legend(loc="upper right", fontsize=8)

        # 2) raw inter-fly distance (per frame)
        ax_dist.plot(dist["t_s"], dist["dist_px"], lw=0.4, alpha=0.6, color="steelblue")
        ax_dist.axvline(KNOWN_OPENING_S, color="red", lw=1, ls="--")
        ax_dist.set_ylabel("dist (px)")
        ax_dist.set_xlim(*XLIM)
        if roi == 1:
            ax_dist.set_title("Per-frame inter-fly distance")

        # 3) sliding window: MIN inter-fly distance in window
        ax_min.plot(windowed["mid_t"], windowed["min_dist"], color="darkgreen", label="min")
        ax_min.plot(windowed["mid_t"], windowed["mean_dist"], color="purple",  label="mean", lw=0.8)
        ax_min.axvline(KNOWN_OPENING_S, color="red", lw=1, ls="--")
        ax_min.set_ylabel("dist (px)")
        ax_min.set_xlim(*XLIM)
        if roi == 1:
            ax_min.set_title(f"min/mean inter-fly distance over {WINDOW_S}s window")
            ax_min.legend(loc="upper right", fontsize=8)

    for ax in axes[-1]:
        ax.set_xlabel("time (s)")

    fig.suptitle(
        f"Barrier-opening signal exploration\n"
        f"machine 076, session 16-03-10  ·  ground truth: {KNOWN_OPENING_S}s",
        fontsize=14,
    )
    fig.tight_layout()

    FIGURES.mkdir(parents=True, exist_ok=True)
    out = FIGURES / "barrier_signal_076_16-03-10.png"
    fig.savefig(out, dpi=120, bbox_inches="tight")
    print(f"saved {out}")


if __name__ == "__main__":
    main()