import gc
import logging
import time
from pathlib import Path

import numpy as np
import pandas as pd
from gomez_cloud.utils.date_utils import iterate_days

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s | %(levelname)s | %(name)s | %(message)s",
)
log = logging.getLogger(__name__)


def _haversine_m(lat1, lon1, lat2, lon2):
    """Vectorised haversine distance in meters."""
    R = 6371000.0
    phi1 = np.radians(lat1); phi2 = np.radians(lat2)
    dphi = np.radians(lat2 - lat1); dl = np.radians(lon2 - lon1)
    a = np.sin(dphi/2)**2 + np.cos(phi1)*np.cos(phi2)*np.sin(dl/2)**2
    return 2*R*np.arcsin(np.sqrt(a))


def _meters_to_deg(lat_deg, dx_m, dy_m):
    """Convert local meter offsets (east=dx, north=dy) to lon/lat degrees at given latitude."""
    lat_rad = np.radians(lat_deg)
    m_per_deg_lat = 111_320.0
    m_per_deg_lon = 111_320.0 * np.cos(lat_rad)
    dlat = dy_m / m_per_deg_lat
    dlon = dx_m / m_per_deg_lon
    return dlat, dlon


def jitter_points(df, lat_col, lon_col, radius_m=50, seed=42, shuffle=True):
    """
    Add uniform random jitter within a circle of radius_m meters.
    Returns a new DataFrame with columns <lat_col>_jit, <lon_col>_jit.
    """
    rng = np.random.default_rng(seed)
    n = len(df)
    # uniform in disk: r = R*sqrt(u), theta ~ U[0,2pi)
    u = rng.random(n)
    r = radius_m * np.sqrt(u)
    theta = rng.random(n) * 2*np.pi
    dx = r * np.cos(theta)
    dy = r * np.sin(theta)

    lat = df[lat_col].to_numpy(dtype=float, copy=False)
    dlat, dlon = _meters_to_deg(lat, dx, dy)

    out = df.copy()
    out[f"{lat_col}_jit"] = lat + dlat
    out[f"{lon_col}_jit"] = df[lon_col].to_numpy(dtype=float, copy=False) + dlon

    if shuffle:
        out = out.sample(frac=1.0, random_state=seed).reset_index(drop=True)
    return out


def jitter_signal(series, sigma_db=2.0, seed=42, clip=(-120, -20)):
    """
    Add small Gaussian noise (dBm) to signal, robust to strings like '-083'.
    """
    rng = np.random.default_rng(seed)
    sig = pd.to_numeric(series, errors="coerce")  # "-083" -> -83
    noise = rng.normal(0.0, sigma_db, size=len(sig))
    out = (sig + noise).clip(clip[0], clip[1])
    return out


# ----- difference metrics -----
def displacement_stats(orig_lat, orig_lon, jit_lat, jit_lon):
    d = _haversine_m(orig_lat, orig_lon, jit_lat, jit_lon)
    return {
        "n": d.size,
        "mean_m": float(np.nanmean(d)),
        "p50_m": float(np.nanpercentile(d, 50)),
        "p90_m": float(np.nanpercentile(d, 90)),
        "p95_m": float(np.nanpercentile(d, 95)),
        "max_m":  float(np.nanmax(d)),
    }


def js_distance_2d(orig_lat, orig_lon, jit_lat, jit_lon, bins=100, eps=1e-12):
    """
    Jensen–Shannon distance between 2D (lat,lon) distributions via hist2d.
    Range: 0 identical … 1 very different (we return sqrt(JS divergence)).
    """
    lat_all = np.concatenate([orig_lat, jit_lat])
    lon_all = np.concatenate([orig_lon, jit_lon])
    lat_edges = np.linspace(lat_all.min(), lat_all.max(), bins+1)
    lon_edges = np.linspace(lon_all.min(), lon_all.max(), bins+1)

    H1, _, _ = np.histogram2d(orig_lat, orig_lon, bins=[lat_edges, lon_edges])
    H2, _, _ = np.histogram2d(jit_lat,  jit_lon,  bins=[lat_edges, lon_edges])

    P = (H1.ravel() + eps); P /= P.sum()
    Q = (H2.ravel() + eps); Q /= Q.sum()
    M = 0.5*(P+Q)

    def kl(p, q):  # both already have eps
        return np.sum(p * np.log(p/q))
    js_div = 0.5*kl(P, M) + 0.5*kl(Q, M)
    return float(np.sqrt(js_div))


def ks_1d_marginals(orig, jit):
    """Kolmogorov–Smirnov D for 1D arrays (simple numpy implementation)."""
    x = np.sort(np.asarray(orig))
    y = np.sort(np.asarray(jit))
    # empirical CDFs on merged support
    grid = np.sort(np.unique(np.concatenate([x, y])))
    Fx = np.searchsorted(x, grid, side='right') / x.size
    Fy = np.searchsorted(y, grid, side='right') / y.size
    return float(np.max(np.abs(Fx - Fy)))


def main() -> None:
    start_all = time.time()

    partitions = iterate_days(first="2025-03-01", last="2025-06-30")

    output_dir = Path(...)
    output_dir.mkdir(parents=True, exist_ok=True)

    base_uri = ...
    storage_opts = {"token": "cloud"}  # ADC via gcsfs

    week_buffers = []
    week_idx = 1
    day_idx = 0
    total_rows_written = 0
    total_days_processed = 0

    for day in partitions:
        t0 = time.time()
        uri = f"{base_uri}/day={day}"

        try:
            df = pd.read_parquet(uri, storage_options=storage_opts)
        except FileNotFoundError:
            log.warning("Partition not found (skipping): %s", uri)
            continue
        except Exception as e:
            log.exception("Failed to read partition %s: %s", uri, e)
            continue

        log.info("Loaded %s rows x %s cols from %s", len(df), len(df.columns), uri)

        try:
            # Jitter location
            pings_jit = jitter_points(
                df,
                lat_col="latitude",
                lon_col="longitude",
                radius_m=20,
                seed=456,
                shuffle=True,
            )
            # Jitter signal
            pings_jit["signal_level_jit"] = jitter_signal(
                df["signal_level"], sigma_db=2.0, seed=456
            )

            # Replace originals with jittered
            pings_jit = (
                pings_jit.drop(columns=["latitude", "longitude", "signal_level"])
                .rename(
                    columns={
                        "latitude_jit": "latitude",
                        "longitude_jit": "longitude",
                        "signal_level_jit": "signal_level",
                    }
                )
            )

            # Keep only 'Full Service Loss (>120s)', else set to None
            if "measurement_type_name" in pings_jit.columns:
                pings_jit["measurement_type_name"] = pings_jit["measurement_type_name"].apply(
                    lambda x: x if x == "Full Service Loss (>120s)" else None
                )
            else:
                log.warning("Column 'measurement_type_name' missing in partition %s", day)

            log.info(
                "Transformed day=%s → %s rows", day, len(pings_jit)
            )

            week_buffers.append(pings_jit)
            total_days_processed += 1
            day_idx += 1

        except Exception as e:
            log.exception("Transform failed for day=%s: %s", day, e)
            # Drop heavy refs before moving on
            del df
            gc.collect()
            continue
        finally:
            # free the original df ASAP
            del df
            gc.collect()

        # Flush every 14 days
        if day_idx % 14 == 0:
            try:
                week_df = pd.concat(week_buffers, ignore_index=True)
                out_path = output_dir / f"np_extract_part_{week_idx}.csv"
                week_df.to_csv(out_path, index=False)
                total_rows_written += len(week_df)
                log.info(
                    "Wrote week %d: %s rows to %s (elapsed %.2fs)",
                    week_idx, len(week_df), out_path, time.time() - t0
                )
            finally:
                week_buffers.clear()
                week_idx += 1
                # encourage memory to return
                del week_df
                gc.collect()

        log.info("Processed day=%s in %.2fs", day, time.time() - t0)

    # Final partial week flush
    if week_buffers:
        week_df = pd.concat(week_buffers, ignore_index=True)

        week_df.to_csv(f"/home/tom_freeman_vodafone_com/tom-foolery/data/np_extractions/part_{week_idx}.csv", index=False)

        total_rows_written += len(week_df)
        log.info(
            "Wrote FINAL part %d: %s rows to %s",
            week_idx, len(week_df), out_path
        )
        week_buffers.clear()
        del week_df
        gc.collect()

    log.info(
        "Done. Days processed: %d | Rows written: %d | Total time: %.2fs",
        total_days_processed, total_rows_written, time.time() - start_all
    )


if __name__ == "__main__":
    main()