#!/usr/bin/env python3
"""
Full DeepSeek-V4 attention pipeline test with real weights.

Architecture (NOT MLA — CSA/HCA):
1. q_a_proj (7168→1536) + kv_proj (7168→512) — NVFP4 CuTeDSL
2. q_norm + kv_norm — RMS
3. q_b_proj (1536→65536) — NVFP4 CuTeDSL
4. RoPE on Q (GPT-J, 64 dims)
5. SWA attention (sliding window=128, causal, SDPA) — BF16
6. o_a: inverse RoPE + BMM with (16, 1024, 8192) — BF16
7. o_b: (T, 16384→7168) — NVFP4 CuTeDSL

For CSA/HCA layers, step 5 would be sparse attention with indexed positions.
This test uses SWA-only (layer 60, compress_ratio=0) and C128A (layer 0)
to test both paths.

Usage (on B200):
  cd /root/nvfp4-megamoe-kernel
  PYTHONPATH=/root/nvfp4-megamoe-kernel tests/venv/bin/python tests/test_v4_attention_b200.py
"""

import sys, os, json, torch, torch.nn.functional as F, math
from safetensors import safe_open

REPO = "/root/nvfp4-megamoe-kernel"
sys.path.insert(0, REPO)
MODEL = "/root/nvidia-meeting/DeepSeek-V4-Pro-NVFP4"
DEV = "cuda:0"

# Model config
H = 7168; NH = 128; HD = 512; NOPE = 448; ROPE = 64
QL = 1536; OL = 1024; OG = 16; HPG = NH // OG
EPS = 1e-6; WINDOW = 128; SCALE = HD ** -0.5

E2M1 = torch.tensor([0,.5,1.,1.5,2.,3.,4.,6.,-0,-.5,-1.,-1.5,-2.,-3.,-4.,-6.], dtype=torch.float32)

_cache = {}
def P(k, wm, md):
    if k in _cache: return _cache[k]
    with safe_open(os.path.join(md, wm[k]), framework="pt") as f:
        t = f.get_tensor(k)
    _cache[k] = t
    return t

def dequant(w, sf, gs):
    d = w.device; lut = E2M1.to(d)
    lo = lut[(w & 0xF).long()]; hi = lut[((w >> 4) & 0xF).long()]
    O, I2 = w.shape; I = I2*2
    u = torch.empty(O, I, dtype=torch.float32, device=d)
    u[:,0::2] = lo; u[:,1::2] = hi
    bs = sf.float().repeat_interleave(16, dim=1)[:O,:I]
    return (u * bs * gs).to(torch.bfloat16)

def rms(x, w, eps=1e-6):
    v = x.float().pow(2).mean(-1, keepdim=True)
    return (w.float() * (x * torch.rsqrt(v+eps)).float()).to(x.dtype)

def make_runner(w, sf, gs_t, inf, outf, fused=False, lw=None):
    from dsv4.layers.linear import Nvfp4Linear
    fp4 = w.view(torch.float4_e2m1fn_x2).permute(1,0).contiguous()
    s = sf.to(torch.float8_e4m3fn) if sf.dtype != torch.float8_e4m3fn else sf
    s = s.permute(1,0).contiguous()
    if fused and gs_t.numel() == 2:
        g1,g2 = gs_t[0].item(), gs_t[1].item(); gs = max(g1,g2)
        if g1 != g2:
            s32 = s.float(); sp = lw[0] if lw else outf//2
            s32[:sp] *= g1/gs; s32[sp:] *= g2/gs; s = s32.to(torch.float8_e4m3fn)
    else:
        gs = gs_t.max().item() if gs_t.numel() > 1 else gs_t.item()
    r = Nvfp4Linear(in_features=inf, out_features=outf, max_num_tokens=8192, device=str(w.device))
    r.fp4 = [fp4]; r.sf = [s]; r.gs = [gs]
    r.finalize_weights(); r._ensure_initialized()
    return r

def apply_gptj_rope(x, positions, cos_sin, nope, rope):
    if rope == 0 or x.numel() == 0: return x
    half = rope // 2
    cos = cos_sin[positions, :half].to(x.dtype)
    sin = cos_sin[positions, half:2*half].to(x.dtype)
    if x.dim() == 3: cos = cos.unsqueeze(1); sin = sin.unsqueeze(1)
    x_rope = x[..., nope:].clone()
    even = x_rope[..., 0::2]; odd = x_rope[..., 1::2]
    out = x.clone()
    out[..., nope:][..., 0::2] = even * cos - odd * sin
    out[..., nope:][..., 1::2] = even * sin + odd * cos
    return out

def apply_inv_gptj_rope(x, positions, cos_sin, nope, rope):
    """Inverse RoPE: same as forward but sin → -sin."""
    if rope == 0 or x.numel() == 0: return x
    half = rope // 2
    cos = cos_sin[positions, :half].to(x.dtype)
    sin = cos_sin[positions, half:2*half].to(x.dtype)
    if x.dim() == 3: cos = cos.unsqueeze(1); sin = sin.unsqueeze(1)
    x_rope = x[..., nope:].clone()
    even = x_rope[..., 0::2]; odd = x_rope[..., 1::2]
    out = x.clone()
    out[..., nope:][..., 0::2] = even * cos + odd * sin
    out[..., nope:][..., 1::2] = -even * sin + odd * cos
    return out

def build_cos_sin(max_pos=4096, rope_dim=ROPE):
    half = rope_dim // 2
    inv_freq = 1.0 / (10000.0 ** (torch.arange(0, half, dtype=torch.float32) / half))
    freqs = torch.outer(torch.arange(max_pos, dtype=torch.float32), inv_freq)
    return torch.cat([freqs.cos(), freqs.sin()], dim=-1)


def swa_attention(q, kv, scale, window_size=WINDOW):
    """Sliding window attention using SDPA.
    
    q: (T, NH, HD) with RoPE
    kv: (T, HD) shared KV latent
    For SWA: attend to last window_size tokens only.
    """
    T, NH, HD = q.shape
    if T <= window_size:
        # Full attention within window
        return full_causal_attention(q, kv, scale)
    
    # For long sequences, only attend to window
    # This is a simplified version — production would use paged cache
    q_2d = q.reshape(T * NH, HD)
    kv_exp = kv.unsqueeze(1).expand(-1, NH, -1).contiguous()
    k_2d = kv_exp.permute(1, 0, 2).unsqueeze(1).expand(NH, T, T, -1).contiguous().reshape(T * NH, T, HD)
    v_2d = k_2d.clone()
    scores = torch.matmul(q_2d.unsqueeze(1), k_2d.transpose(-1, -2)) * scale
    query_pos = torch.arange(T, device=q.device).unsqueeze(1).repeat(1, NH).reshape(T * NH)
    kv_pos = torch.arange(T, device=q.device).unsqueeze(0)
    causal = kv_pos <= query_pos.unsqueeze(1)
    window = kv_pos >= (query_pos.unsqueeze(1) - window_size + 1)
    mask = causal & window
    scores = scores.squeeze(1).masked_fill(~mask, float('-inf'))
    weights = F.softmax(scores.float(), dim=-1).to(q.dtype)
    out = torch.matmul(weights.unsqueeze(1), v_2d).squeeze(1)
    return out.reshape(T, NH, HD)


def full_causal_attention(q, kv, scale):
    """Full causal self-attention (for testing with T <= window_size)."""
    T, NH, HD = q.shape
    q_2d = q.reshape(T * NH, HD)
    kv_exp = kv.unsqueeze(1).expand(-1, NH, -1).contiguous()
    k_2d = kv_exp.permute(1, 0, 2).unsqueeze(1).expand(NH, T, T, -1).contiguous().reshape(T * NH, T, HD)
    v_2d = k_2d.clone()
    scores = torch.matmul(q_2d.unsqueeze(1), k_2d.transpose(-1, -2)) * scale
    query_pos = torch.arange(T, device=q.device).unsqueeze(1).repeat(1, NH).reshape(T * NH)
    kv_pos = torch.arange(T, device=q.device).unsqueeze(0)
    causal = kv_pos <= query_pos.unsqueeze(1)
    scores = scores.squeeze(1).masked_fill(~causal, float('-inf'))
    weights = F.softmax(scores.float(), dim=-1).to(q.dtype)
    out = torch.matmul(weights.unsqueeze(1), v_2d).squeeze(1)
    return out.reshape(T, NH, HD)


def test_layer(layer_id, compress_ratio):
    """Test the full attention pipeline for a specific layer."""
    torch.cuda.set_device(0)
    torch.manual_seed(42)
    torch.cuda.empty_cache()
    
    with open(os.path.join(MODEL, "model.safetensors.index.json")) as f:
        wm = json.load(f)["weight_map"]
    G = lambda k: P(k, wm, MODEL).to(DEV)
    
    p = f"model.layers.{layer_id}"; a = f"{p}.self_attn"
    layer_type = "SWA" if compress_ratio <= 1 else f"CSA(c={compress_ratio})"
    
    print(f"\n{'='*70}")
    print(f"  Layer {layer_id} — {layer_type}")
    print(f"{'='*70}")
    
    # Load weights
    emb = G("model.embed_tokens.weight")
    anorm = G(f"{p}.input_layernorm.weight")
    qn = G(f"{a}.q_a_norm.weight"); kvn = G(f"{a}.kv_norm.weight")
    woa = G(f"{a}.o_a_proj.weight")  # (16384, 8192) BF16
    
    qa_w = G(f"{a}.q_a_proj.weight"); qa_sf = G(f"{a}.q_a_proj.weight_scale"); qa_gs = G(f"{a}.q_a_proj.weight_scale_2")
    qb_w = G(f"{a}.q_b_proj.weight"); qb_sf = G(f"{a}.q_b_proj.weight_scale"); qb_gs = G(f"{a}.q_b_proj.weight_scale_2")
    kv_w = G(f"{a}.kv_proj.weight"); kv_sf = G(f"{a}.kv_proj.weight_scale"); kv_gs = G(f"{a}.kv_proj.weight_scale_2")
    wob_w = G(f"{a}.o_b_proj.weight"); wob_sf = G(f"{a}.o_b_proj.weight_scale"); wob_gs = G(f"{a}.o_b_proj.weight_scale_2")
    sinks = G(f"{a}.sinks")
    
    # BF16 references
    qa_bf16 = dequant(qa_w, qa_sf, qa_gs.item())
    qb_bf16 = dequant(qb_w, qb_sf, qb_gs.item())
    kv_bf16 = dequant(kv_w, kv_sf, kv_gs.item())
    wob_bf16 = dequant(wob_w, wob_sf, wob_gs.item())
    
    # CuTeDSL runners
    r_qa = make_runner(qa_w, qa_sf, qa_gs, H, qa_w.shape[0])
    r_qb = make_runner(qb_w, qb_sf, qb_gs, QL, qb_w.shape[0])
    r_kv = make_runner(kv_w, kv_sf, kv_gs, H, kv_w.shape[0])
    r_wob = make_runner(wob_w, wob_sf, wob_gs, OG*OL, wob_w.shape[0])
    
    # Input
    NT = 6
    token_ids = torch.tensor([1, 450, 8403, 315, 5413, 374], dtype=torch.long, device=DEV)
    cos_sin = build_cos_sin(max_pos=WINDOW + 256).to(DEV)
    positions = torch.arange(NT, dtype=torch.int64, device=DEV)
    
    with torch.no_grad():
        hidden = emb[token_ids]
        normed = rms(hidden, anorm, EPS)
        
        # ── CuTeDSL path ─────────────────────────────────────────────
        qa_cute = r_qa.run(normed)
        kv_cute = r_kv.run(normed)
        qa_n = rms(qa_cute, qn, EPS)
        kv_n = rms(kv_cute, kvn, EPS)
        q_cute = r_qb.run(qa_n).view(NT, NH, HD)
        q_rope = apply_gptj_rope(q_cute, positions, cos_sin, NOPE, ROPE)
        
        # SWA attention (for T=6, full causal within window)
        o_attn = full_causal_attention(q_rope, kv_n, SCALE)
        
        # o_a: inverse RoPE + BMM
        o_inv = apply_inv_gptj_rope(o_attn, positions, cos_sin, NOPE, ROPE)
        o_grouped = o_inv.view(NT, OG, HPG * HD).permute(1, 0, 2)
        woa_3d = woa.view(OG, OL, HPG * HD)
        z_cute = torch.bmm(o_grouped, woa_3d.transpose(1, 2)).permute(1, 0, 2).reshape(NT, OG * OL)
        
        # o_b
        attn_out = r_wob.run(z_cute)
        
        # ── BF16 reference ───────────────────────────────────────────
        qa_bf = normed @ qa_bf16.T
        kv_bf = normed @ kv_bf16.T
        qa_n_bf = rms(qa_bf, qn, EPS)
        kv_n_bf = rms(kv_bf, kvn, EPS)
        q_bf = (qa_n_bf @ qb_bf16.T).view(NT, NH, HD)
        q_rope_bf = apply_gptj_rope(q_bf, positions, cos_sin, NOPE, ROPE)
        o_attn_bf = full_causal_attention(q_rope_bf, kv_n_bf, SCALE)
        o_inv_bf = apply_inv_gptj_rope(o_attn_bf, positions, cos_sin, NOPE, ROPE)
        o_grouped_bf = o_inv_bf.view(NT, OG, HPG * HD).permute(1, 0, 2)
        z_bf = torch.bmm(o_grouped_bf, woa_3d.transpose(1, 2)).permute(1, 0, 2).reshape(NT, OG * OL)
        attn_bf = z_bf @ wob_bf16.T
        
        # ── Compare ──────────────────────────────────────────────────
        c = F.cosine_similarity(attn_out.flatten().unsqueeze(0).float(), attn_bf.flatten().unsqueeze(0).float()).item()
        print(f"  CuTeDSL vs BF16 cosine: {c:.6f} {'✅' if c>=0.95 else '❌'}")
        print(f"  CuTeDSL amax: {attn_out.amax():.4f}  BF16 amax: {attn_bf.amax():.4f}")
        
        # Full forward: attention → residual → norm → LM head
        fnorm_w = G("model.norm.weight")
        lm_head = G("lm_head.weight")
        x = hidden + attn_out
        x_normed = rms(x, fnorm_w, EPS)
        logits = x_normed @ lm_head.T
        top5 = torch.topk(logits[-1], 5)
        log_std = logits[-1].float().std().item()
        print(f"  logits: amax={logits.amax():.4f} std={log_std:.4f} top5={top5.indices.tolist()}")
        print(f"  logit check: {'✅' if 0.5 < log_std < 50 else '❌'} (0.5 < std < 50)")
    
    # Cleanup
    del r_qa, r_qb, r_kv, r_wob
    torch.cuda.empty_cache()
    return c


def main():
    print("=" * 70)
    print("  DeepSeek-V4 CSA/HCA Attention Pipeline Test")
    print("  (NOT MLA — Compressed Sparse Attention)")
    print("=" * 70)
    
    # Test SWA layer (layer 60, compress_ratio=0)
    c_swa = test_layer(60, 0)
    
    # Test C128A layer (layer 0, compress_ratio=128)
    c_c128 = test_layer(0, 128)
    
    # Test C4A layer (layer 2, compress_ratio=4)
    c_c4 = test_layer(2, 4)
    
    print(f"\n{'='*70}")
    print(f"  SUMMARY")
    print(f"  Layer 60 (SWA):       {c_swa:.6f} {'✅' if c_swa>=0.95 else '❌'}")
    print(f"  Layer 0  (C128A/HCA): {c_c128:.6f} {'✅' if c_c128>=0.95 else '❌'}")
    print(f"  Layer 2  (C4A/CSA):   {c_c4:.6f} {'✅' if c_c4>=0.95 else '❌'}")
    print(f"{'='*70}")


if __name__ == "__main__":
    main()