r"""
train_v3.py — AtmosIQ v3.1 training. Architecture FROZEN (model.py verbatim). Protocol pins:
  TP-1 full pruned-graph training (mean-degree assert in dataset_v3; sampler deleted)
  TP-2 ORPHAN masking in finetune (p_orphan labeled nodes: Group A blackout all T,
       completeness->0, labels still supervised -> gradient must route via neighbors)
  TP-3 physics losses ON by default (lam_phys=0.05)
  TP-4 loud guards: per-epoch skip-rate; > max_skip -> hard ABORT
  TP-5 coordinate jitter in finetune (Gaussian on projection_x/y, sigma=0.1 std ~15-25km):
       kills exact-position lookup shortcut while keeping coarse positional signal
  P0-1 stride-sampled val/probe-eval days (season-balanced, deterministic)
  P0-2 finetune val on train+val graph ONLY (test nodes never context for model selection);
       probe EVAL stays full-graph per SSL_ROADMAP §7 pin (held-out nodes must be present)
Stages: pretrain -> probe (raw-space R², branch suggestion, PROVISIONAL until refs.json
space confirmed) -> finetune (early stop on season-balanced val NLL).
Checkpoints: <tensors>/../encoder_v3.pt , atmosiq_v3_best.pt , train_state_v3.json
Run: python data/models_v3/train_v3.py --tensors data/tensors --stage all
"""
from __future__ import annotations
import os, sys, json, argparse, pathlib, time
import numpy as np, torch, torch.nn as nn, torch.nn.functional as F
torch.set_num_threads(os.cpu_count() or 8)
sys.path.insert(0, str(pathlib.Path(__file__).resolve().parent))
from model import AtmosIQNet, student_t_nll, ssl_recon_loss
from dataset_v3 import AtmosDataV3, ssl_mask, recon_from_groups, recon_masked

POLL = ["pm2_5", "pm10", "no2", "so2", "co", "o3", "nh3"]
COORD_IDX = (1, 2)   # static_num layout: [elevation, proj_x, proj_y, d_hwy, d_ind, +4 yearly]

def stride(days, k):
    """Season-balanced deterministic subset: every len/k-th day (P0-1)."""
    if not k or k >= len(days): return list(days)
    s = max(1, len(days) // k)
    return list(days)[::s][:k]

def grads_finite(net):
    for p in net.parameters():
        if p.grad is not None and not torch.isfinite(p.grad).all(): return False
    return True

def build_model(meta, dev):
    n_recon = 9 + meta["dimsB"] + meta["dimsC_static"] + meta["dimsC_yearly"]
    cfg = {"calendar_num_dim": meta["dimsD_num"], "n_recon_channels": n_recon,
           "categorical": {"land_use_class": 4, "grap_stage": 3,
                           "n_landuse": meta["n_landuse"], "n_grap": meta["n_grap"]}}
    return AtmosIQNet(cfg).to(dev), cfg

def epoch_guard(name, skips, steps, max_skip):
    rate = skips / max(steps, 1)
    print(f"  [{name}] skip_rate={rate:.1%} ({skips}/{steps})", flush=True)
    if rate > max_skip:
        raise SystemExit(f"ABORT TP-4: {name} skip-rate {rate:.1%} > {max_skip:.0%} — "
                         f"numerics broke; fix before continuing (no zombie runs).")

def jitter_coords(groups_t, sigma):
    """TP-5: one noise draw per window (static must not wiggle per day), finetune only."""
    if sigma <= 0: return groups_t
    N = groups_t[0]["static_num"].shape[0]; dev = groups_t[0]["static_num"].device
    noise = torch.randn(N, len(COORD_IDX), device=dev) * sigma
    out = []
    for g in groups_t:
        g2 = dict(g); s = g2["static_num"].clone()
        s[:, COORD_IDX[0]] += noise[:, 0]; s[:, COORD_IDX[1]] += noise[:, 1]
        g2["static_num"] = s; out.append(g2)
    return out

def smoothness(net, b, gm, h_seq):
    """§3 with detached anchor (P1-4, memory): gradient flows through the perturbed
    branch only — pulls h(x+delta) toward h(x). Recorded deviation from symmetric form."""
    noisy = [{k: (v + 0.1 * torch.randn_like(v) if k in ("satellite", "meteorology", "static_num", "calendar_num") else v)
              for k, v in g.items()} for g in b["groups_t"]]
    h2 = net.encode(noisy, b["ei"], b["e_hat"], b["n_hat"], b["wu"], b["wv"], b["blh"], gm)
    return ((h_seq.detach() - h2) ** 2).mean()

# ---------------------------------------------------------------- pretrain
def pretrain(data, net, a, dev, tv):
    opt = torch.optim.AdamW(net.parameters(), lr=a.lr, weight_decay=1e-4)
    days = list(range(data.w - 1, data.D))
    for ep in range(a.ssl_epochs):
        net.train(); np.random.shuffle(days); tot = 0; n_ok = 0; skips = 0; t0 = time.time()
        used = days[:a.days_per_epoch] if a.days_per_epoch else days
        for i, t in enumerate(used):
            b = data.window(t, tv)
            gm = ssl_mask(b["groups_t"])
            h_seq = net.encode(b["groups_t"], b["ei"], b["e_hat"], b["n_hat"], b["wu"], b["wv"], b["blh"], gm)
            recon = net.recon(h_seq)
            tgt, obs = recon_from_groups(b["groups_t"])
            L_rec = ssl_recon_loss(recon, tgt, recon_masked(gm) * obs)
            loss = L_rec
            if a.lam_smooth > 0 and (i % a.smooth_every == 0):
                loss = loss + a.lam_smooth * smoothness(net, b, gm, h_seq)
            opt.zero_grad()
            if not torch.isfinite(loss): skips += 1; continue
            loss.backward()
            if not grads_finite(net): opt.zero_grad(); skips += 1; continue
            torch.nn.utils.clip_grad_norm_(net.parameters(), 5.0)
            opt.step(); tot += L_rec.item(); n_ok += 1
            if (i + 1) % a.log_every == 0:
                print(f"  [SSL {ep+1}] {i+1}/{len(used)} recon={tot/max(n_ok,1):.4f} "
                      f"{(time.time()-t0)/(i+1):.2f}s/it", flush=True)
        print(f"[SSL {ep+1}/{a.ssl_epochs}] recon_mse={tot/max(n_ok,1):.4f} {time.time()-t0:.0f}s", flush=True)
        epoch_guard(f"SSL {ep+1}", skips, len(used), a.max_skip)
    ck = pathlib.Path(a.tensors).parent / "encoder_v3.pt"
    torch.save(net.state_dict(), ck); print(f"-> {ck}")

# ---------------------------------------------------------------- probe (§7)
def probe(data, net, meta, a, dev, tv):
    ck = pathlib.Path(a.tensors).parent / "encoder_v3.pt"
    if ck.exists():
        net.load_state_dict(torch.load(ck, map_location=dev)); print("loaded encoder_v3.pt")
    for p in net.parameters(): p.requires_grad = False
    net.eval()
    nz = np.load(pathlib.Path(a.tensors) / "norm.npz")
    ylm = torch.tensor(nz["y_logmean"]).float().to(dev)
    yls = torch.tensor(nz["y_logstd"]).float().to(dev)
    lin = nn.Linear(meta.get("d_model", 96), 7).to(dev)
    opt = torch.optim.Adam(lin.parameters(), lr=1e-2)
    tr_days = data.target_days(0)
    tr_node_mask = (data.split[tv["nodes"]] == 0).float().unsqueeze(-1).to(dev)
    for ep in range(a.probe_epochs):
        np.random.shuffle(tr_days); tot = 0; t0 = time.time(); dd = tr_days[:a.probe_days]
        for i, t in enumerate(dd):
            b = data.window(t, tv)                       # PRUNED train graph (probe trains here)
            with torch.no_grad():
                z = net.encode(b["groups_t"], b["ei"], b["e_hat"], b["n_hat"], b["wu"], b["wv"], b["blh"])[:, -1]
            pred = lin(z)
            yl = (torch.log(b["y"][:, 0, :].clamp_min(0) + 1e-3) - ylm) / yls
            m = b["m"][:, 0, :] * tr_node_mask
            loss = ((pred - yl) ** 2 * m).sum() / m.sum().clamp_min(1)
            opt.zero_grad(); loss.backward(); opt.step(); tot += loss.item()
            if (i + 1) % 10 == 0:
                print(f"  [PROBE {ep+1}] {i+1}/{len(dd)} mse={tot/(i+1):.3f} {(time.time()-t0)/(i+1):.2f}s/it", flush=True)
        print(f"[PROBE {ep+1}/{a.probe_epochs}] {time.time()-t0:.0f}s", flush=True)
    # ---- eval: FULL graph (SSL_ROADMAP §7 pin), season-balanced days (P0-1), raw-space R²
    fv = data.graph_view(None, "full")
    te = (data.split == 2).float().unsqueeze(-1).to(dev)
    ev_days = stride(data.target_days(2), a.probe_days)
    ys = []; ps = []; ms = []
    with torch.no_grad():
        for t in ev_days:
            b = data.window(t, fv)
            z = net.encode(b["groups_t"], b["ei"], b["e_hat"], b["n_hat"], b["wu"], b["wv"], b["blh"])[:, -1]
            mu = lin(z) * yls.view(1, -1) + ylm.view(1, -1)
            pred = (torch.exp(mu.clamp(max=12)) - 1e-3).clamp_min(0)
            ys.append(b["y"][:, 0, :]); ps.append(pred); ms.append(b["m"][:, 0, :] * te)
    Y = torch.cat(ys); P = torch.cat(ps); M = torch.cat(ms)
    assert int((M.sum(-1) > 0).sum()) > 0, "probe eval produced no held-out predictions — full-graph forward broken"
    refs = json.load(open(a.refs)) if a.refs and os.path.exists(a.refs) else {}
    print(f"\n§7 LINEAR PROBE — spatial-held-out RAW-space R², {len(ev_days)} season-balanced days:")
    print("NOTE: branch PROVISIONAL until refs.json R²-space (raw vs log) is confirmed against M1 eval code.")
    res = {}
    for j, pn in enumerate(POLL):
        mm = M[:, j] > 0
        if mm.sum() < 5: print(f"  {pn}: n<5 skip"); continue
        y = Y[mm, j].cpu().numpy(); p = P[mm, j].cpu().numpy()
        r2 = 1 - ((y - p) ** 2).sum() / (((y - y.mean()) ** 2).sum() + 1e-9)
        xg = refs.get(pn, {}).get("xgboost")
        gap = float(r2 / xg) if (xg is not None and xg > 0) else None
        res[pn] = dict(r2=float(r2), xgb=xg, gap_closed=gap)
        gtag = f" gap_closed={gap:+.0%}" if gap is not None else ""
        print(f"  {pn}: probe R²={r2:+.3f}" + (f" (xgb {xg:+.2f}){gtag}" if xg is not None else ""))
    pm = res.get("pm2_5", {})
    sparse_set = ["so2", "co", "o3", "nh3"]
    pm_pass = pm.get("xgb") is not None and pm.get("r2", -9) >= pm["xgb"]
    sp_pass = any(res.get(s, {}).get("xgb") is not None and res[s]["r2"] >= res[s]["xgb"] for s in sparse_set)
    if pm_pass and sp_pass: verdict = "FROZEN (pm2_5 AND >=1 sparse match-or-beat)"
    elif pm.get("gap_closed") is not None and pm["gap_closed"] < 0.5: verdict = "REFUTED (<50% gap on pm2_5)"
    else: verdict = "INCONCLUSIVE"
    print(f"  suggested branch: {verdict}  — decision is joint, not automatic.")
    json.dump(res | {"suggested_branch": verdict, "provisional_refs_space": True},
              open(pathlib.Path(a.tensors).parent / "probe_result_v3.json", "w"), indent=1)

# ---------------------------------------------------------------- finetune
def physics_losses(pred_log, b):
    pm = pred_log[:, 0, 0]
    blh = b["blh"][-1]; rain = b["groups_t"][-1]["meteorology"][:, 7]
    pm = torch.nan_to_num(pm); blh = torch.nan_to_num(blh); rain = torch.nan_to_num(rain)
    L_blh = F.relu((pm - pm.mean()) * (blh - blh.mean())).mean().clamp(max=10.0)
    L_rain = F.relu((pm - pm.mean()) * (rain - rain.mean())).mean().clamp(max=10.0)
    return torch.nan_to_num(L_blh + L_rain)

def orphan_masks(b, p_orphan):
    """TP-2: p_orphan of today-labeled nodes -> Group A blackout all T + completeness 0."""
    T = len(b["groups_t"])
    lab = (b["m"].sum(1).sum(-1) > 0)
    orph = lab & (torch.rand(lab.shape[0], device=lab.device) < p_orphan)
    of = orph.float()
    return [{"satellite": of} for _ in range(T)], b["comp"] * (1 - of), int(orph.sum())

def finetune(data, net, a, dev, tv, ylm, yls):
    """LP-FT schedule: freeze_epochs of head-only training at --lr (linear-probe phase,
    protects the pretrained representation), then unfreeze ALL at --unfreeze_lr.
    Motivation: probe R2 (frozen encoder) exceeded full-FT R2 on pm2_5 -> naive FT was
    degrading the representation. Val logs BOTH nll and mu-quality (log-space mse),
    because nll can worsen through sigma calibration alone."""
    ck = pathlib.Path(a.tensors).parent / "encoder_v3.pt"
    if ck.exists():
        net.load_state_dict(torch.load(ck, map_location=dev), strict=False); print("loaded pretrained encoder_v3")
    enc_p = [p for n, p in net.named_parameters() if not n.startswith("head.")]
    head_p = [p for n, p in net.named_parameters() if n.startswith("head.")]
    def make_opt(stage):
        if stage == "head":
            for p in enc_p: p.requires_grad = False
            for p in head_p: p.requires_grad = True
            return torch.optim.AdamW(head_p, lr=a.lr, weight_decay=a.weight_decay)
        for p in net.parameters(): p.requires_grad = True
        return torch.optim.AdamW(net.parameters(), lr=a.unfreeze_lr, weight_decay=a.weight_decay)
    opt = make_opt("head" if a.freeze_epochs > 0 else "all")
    print(f"LP-FT: {a.freeze_epochs} head-only epochs @lr={a.lr}, then ALL @lr={a.unfreeze_lr}")
    tr = data.target_days(0)
    vv = data.graph_view([0, 1], "train+val")            # P0-2: test nodes NEVER context here
    van = (data.split[vv["nodes"]] == 1).float().view(-1, 1, 1).to(dev)
    va_days = stride(data.target_days(1), a.val_days)     # P0-1
    print(f"val protocol: {len(va_days)} stride-sampled days on train+val graph")
    best = 1e9; bad = 0
    for ep in range(a.ft_epochs):
        if a.freeze_epochs > 0 and ep == a.freeze_epochs:
            opt = make_opt("all")
            print(f"  [FT] encoder UNFROZEN at epoch {ep+1}, lr -> {a.unfreeze_lr}", flush=True)
        net.train(); np.random.shuffle(tr); tot = 0; n_ok = 0; skips = 0; n_orph = 0; t0 = time.time()
        used = tr[:a.days_per_epoch] if a.days_per_epoch else tr
        for i, t in enumerate(used):
            b = data.window(t, tv)
            b["groups_t"] = jitter_coords(b["groups_t"], a.coord_jitter)   # TP-5
            gm_t, comp, k = (None, b["comp"], 0) if a.p_orphan <= 0 else orphan_masks(b, a.p_orphan)
            n_orph += k
            out = net(b["groups_t"], b["ei"], b["e_hat"], b["n_hat"], b["wu"], b["wv"], b["blh"], comp, gm_t)
            nll = student_t_nll(out["mu"], out["log_sigma"], out["nu"], b["y"], b["m"], ylm, yls)
            phys = physics_losses(out["mu"], b) if a.lam_phys > 0 else torch.tensor(0., device=dev)
            loss = nll + a.lam_phys * phys
            opt.zero_grad()
            if not torch.isfinite(loss): skips += 1; continue
            loss.backward()
            if not grads_finite(net): opt.zero_grad(); skips += 1; continue
            torch.nn.utils.clip_grad_norm_(net.parameters(), 5.0)
            opt.step(); tot += nll.item(); n_ok += 1
            if (i + 1) % a.log_every == 0:
                print(f"  [FT {ep+1}] {i+1}/{len(used)} nll={tot/max(n_ok,1):.3f} "
                      f"{(time.time()-t0)/(i+1):.2f}s/it", flush=True)
        # ---- val: train+val graph, no orphan, no jitter; nll AND mu-quality
        net.eval(); vt = 0; se = 0.0; sn = 0.0
        with torch.no_grad():
            for t in va_days:
                b = data.window(t, vv)
                out = net(b["groups_t"], b["ei"], b["e_hat"], b["n_hat"], b["wu"], b["wv"], b["blh"], b["comp"])
                vt += student_t_nll(out["mu"], out["log_sigma"], out["nu"], b["y"], b["m"] * van, ylm, yls).item()
                yl = (torch.log(b["y"].clamp_min(0) + 1e-3) - ylm.view(1, 1, -1)) / yls.view(1, 1, -1)
                mm = b["m"] * van
                se += (((out["mu"] - yl) ** 2) * mm).sum().item(); sn += mm.sum().item()
        vm = vt / max(len(va_days), 1); vmse = se / max(sn, 1.0)
        print(f"[FT {ep+1}/{a.ft_epochs}] train_nll={tot/max(n_ok,1):.3f} val_nll={vm:.3f} "
              f"val_mse={vmse:.3f} orphaned={n_orph} {time.time()-t0:.0f}s", flush=True)
        epoch_guard(f"FT {ep+1}", skips, len(used), a.max_skip)
        if vmse < best:                     # TP-7: select on mu-quality (val_mse), not nll —
            best = vmse; bad = 0            # nll can worsen via sigma calibration while mu improves
            torch.save(net.state_dict(), pathlib.Path(a.tensors).parent / "atmosiq_v3_best.pt")
        else:
            bad += 1
            if bad >= a.patience:
                print(f"early stop (no val_mse improve for {a.patience} epochs)"); break
    print(f"done. best val_mse={best:.3f} -> atmosiq_v3_best.pt")

# ---------------------------------------------------------------- main
def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--tensors", default="data/tensors")
    ap.add_argument("--stage", default="all", choices=["pretrain", "probe", "finetune", "all"])
    ap.add_argument("--window", type=int, default=7)
    ap.add_argument("--ssl_epochs", type=int, default=8)
    ap.add_argument("--probe_epochs", type=int, default=15)
    ap.add_argument("--ft_epochs", type=int, default=30)
    ap.add_argument("--lr", type=float, default=3e-4)
    ap.add_argument("--lam_smooth", type=float, default=0.1)
    ap.add_argument("--lam_phys", type=float, default=0.0)         # TP-3 amended: covariance proxy REFUTED (EXP-C, pm2_5-h0 0.046->0.270); 0 until true L-1 (perturbation monotonicity)
    ap.add_argument("--p_orphan", type=float, default=0.0)         # TP-2 amended: orphan lives in SSL blackout; inert in head stage (EXP-A/B)
    ap.add_argument("--coord_jitter", type=float, default=0.1)     # TP-5 (0 = ablation arm)
    ap.add_argument("--smooth_every", type=int, default=4)
    ap.add_argument("--days_per_epoch", type=int, default=800)     # 0 = all days
    ap.add_argument("--probe_days", type=int, default=60)
    ap.add_argument("--val_days", type=int, default=25)
    ap.add_argument("--patience", type=int, default=5)
    ap.add_argument("--freeze_epochs", type=int, default=3, help="LP phase: head-only epochs before unfreezing encoder")
    ap.add_argument("--unfreeze_lr", type=float, default=5e-5, help="lr for all params after unfreeze")
    ap.add_argument("--weight_decay", type=float, default=1e-3)
    ap.add_argument("--max_skip", type=float, default=0.20)        # TP-4
    ap.add_argument("--log_every", type=int, default=100)
    ap.add_argument("--refs", default="data/models/refs.json")
    ap.add_argument("--pm25_weight", type=float, default=1.0,
                    help="P4 ablation: pm2_5 weight in TRAIN loss only (val stays unweighted)")
    ap.add_argument("--seed", type=int, default=42)
    a = ap.parse_args()
    torch.manual_seed(a.seed); np.random.seed(a.seed)
    dev = "cuda" if torch.cuda.is_available() else "cpu"; print("device:", dev)
    if dev == "cpu":
        raise SystemExit("ABORT: CUDA unavailable — full-graph training on CPU would take days. "
                         "Fix torch/driver match (nvidia-smi CUDA Version vs torch build).")
    meta = json.load(open(pathlib.Path(a.tensors) / "meta.json"))
    data = AtmosDataV3(a.tensors, window=a.window, device=dev)
    nz = np.load(pathlib.Path(a.tensors) / "norm.npz")
    assert "y_logmean" in nz, "norm.npz missing y_logmean/y_logstd — run add_ystats.py first"
    ylm = torch.tensor(nz["y_logmean"]).float().to(dev)
    yls = torch.tensor(nz["y_logstd"]).float().to(dev)
    net, cfg = build_model(meta, dev)
    print(f"model params: {sum(p.numel() for p in net.parameters()):,}")
    tv = data.graph_view([0], "train")                              # TP-1: THE training graph
    json.dump({"pins": {"TP1_full_graph": True, "TP2_p_orphan": a.p_orphan,
                        "TP3_lam_phys": a.lam_phys, "TP4_max_skip": a.max_skip,
                        "TP5_coord_jitter": a.coord_jitter,
                        "P0_1_stride_days": True, "P0_2_val_graph": "train+val only"},
               "seed": a.seed, "lr": a.lr, "weight_decay": a.weight_decay,
               "train_mean_deg": tv["mean_deg"], "data_tier": data.tier},
              open(pathlib.Path(a.tensors).parent / "train_state_v3.json", "w"), indent=1)
    if a.stage in ("pretrain", "all"): pretrain(data, net, a, dev, tv)
    if a.stage in ("probe", "all"):    probe(data, net, meta, a, dev, tv)
    if a.stage in ("finetune", "all"): finetune(data, net, a, dev, tv, ylm, yls)

if __name__ == "__main__":
    main()