##### Enjoy this spagheti VRAM optimizations done by DeepBeepMeep !
# I am sure you are a nice person and as you copy this code, you will give me officially proper credits:
# Please link to https://github.com/deepbeepmeep/Wan2GP and @deepbeepmeep on twitter  
import torch
import torch.nn as nn
import math
import random
import os
import time
from typing import Tuple, Optional, List
from einops import rearrange
from .utils import hash_state_dict_keys

try:
    from block_sparse_attn import block_sparse_attn_func
    BLOCK_ATTN_AVAILABLE = True
except:
    BLOCK_ATTN_AVAILABLE = False

from .attention_backend import sparse_attention
from shared.attention import get_supported_attention_modes, pay_attention
from mmgp import offload
from PIL import Image
import numpy as np

USE_BLOCK_ATTN = False
_FLASHVSR_ATTENTION_MODE = None


def get_flashvsr_attention_mode():
    global _FLASHVSR_ATTENTION_MODE
    selected = offload.shared_state.get("_attention")
    if selected not in (None, "auto"):
        return selected
    if _FLASHVSR_ATTENTION_MODE is None:
        modes = get_supported_attention_modes()
        _FLASHVSR_ATTENTION_MODE = "sage2" if "sage2" in modes else "sage" if "sage" in modes else "sdpa"
        print(f"[FlashVSR] WanGP dense attention backend: {_FLASHVSR_ATTENTION_MODE}")
    return _FLASHVSR_ATTENTION_MODE

# ----------------------------
# Local / window masks
# ----------------------------
@torch.no_grad()
def build_local_block_mask_shifted_vec(block_h: int,
                                       block_w: int,
                                       win_h: int = 6,
                                       win_w: int = 6,
                                       include_self: bool = True,
                                       device=None) -> torch.Tensor:
    device = device or torch.device("cpu")
    H, W = block_h, block_w
    r = torch.arange(H, device=device)
    c = torch.arange(W, device=device)
    YY, XX = torch.meshgrid(r, c, indexing="ij")
    r_all = YY.reshape(-1)
    c_all = XX.reshape(-1)
    r_half = win_h // 2
    c_half = win_w // 2
    start_r = torch.clamp(r_all - r_half, 0, H - win_h)
    end_r   = start_r + win_h - 1
    start_c = torch.clamp(c_all - c_half, 0, W - win_w)
    end_c   = start_c + win_w - 1
    in_row = (r_all[None, :] >= start_r[:, None]) & (r_all[None, :] <= end_r[:, None])
    in_col = (c_all[None, :] >= start_c[:, None]) & (c_all[None, :] <= end_c[:, None])
    mask = in_row & in_col
    if not include_self:
        mask.fill_diagonal_(False)
    return mask

@torch.no_grad()
def build_local_block_mask_shifted_vec_normal_slide(block_h: int,
                                                   block_w: int,
                                                   win_h: int = 6,
                                                   win_w: int = 6,
                                                   include_self: bool = True,
                                                   device=None) -> torch.Tensor:
    device = device or torch.device("cpu")
    H, W = block_h, block_w
    r = torch.arange(H, device=device)
    c = torch.arange(W, device=device)
    YY, XX = torch.meshgrid(r, c, indexing="ij")
    r_all = YY.reshape(-1)
    c_all = XX.reshape(-1)
    r_half = win_h // 2
    c_half = win_w // 2
    start_r = r_all - r_half
    end_r   = start_r + win_h - 1
    start_c = c_all - c_half
    end_c   = start_c + win_w - 1
    in_row = (r_all[None, :] >= start_r[:, None]) & (r_all[None, :] <= end_r[:, None])
    in_col = (c_all[None, :] >= start_c[:, None]) & (c_all[None, :] <= end_c[:, None])
    mask = in_row & in_col
    if not include_self:
        mask.fill_diagonal_(False)
    return mask


class WindowPartition3D:
    """Partition / reverse-partition helpers for 5-D tensors (B,F,H,W,C)."""
    @staticmethod
    def partition(x: torch.Tensor | list[torch.Tensor], win: Tuple[int, int, int]):
        if isinstance(x, list):
            x_list = x
            x = x_list[0]
            x_list.clear()
        B, F, H, W, C = x.shape
        wf, wh, ww = win
        assert F % wf == 0 and H % wh == 0 and W % ww == 0, "Dims must divide by window size."
        x = x.view(B, F // wf, wf, H // wh, wh, W // ww, ww, C)
        x = x.permute(0, 1, 3, 5, 2, 4, 6, 7).contiguous()
        return x.reshape(-1, wf * wh * ww, C)

    @staticmethod
    def reverse(windows: torch.Tensor | list[torch.Tensor], win: Tuple[int, int, int], orig: Tuple[int, int, int]):
        if isinstance(windows, list):
            windows_list = windows
            windows = windows_list[0]
            windows_list.clear()
        F, H, W = orig
        wf, wh, ww = win
        nf, nh, nw = F // wf, H // wh, W // ww
        B = windows.size(0) // (nf * nh * nw)
        x = windows.view(B, nf, nh, nw, wf, wh, ww, -1)
        x = x.permute(0, 1, 4, 2, 5, 3, 6, 7).contiguous()
        return x.reshape(B, F, H, W, -1)


@torch.no_grad()
def _topk_threshold_mask(flat: torch.Tensor, apply_topk: int) -> torch.Tensor:
    if apply_topk <= 0:
        return torch.zeros_like(flat, dtype=torch.bool)
    threshold_index = flat.shape[1] - apply_topk
    thresholds = flat.kthvalue(threshold_index, dim=1).values.unsqueeze_(1)
    mask = flat > thresholds
    del thresholds
    return mask


@torch.no_grad()
def generate_draft_block_mask(batch_size, nheads, seqlen,
                              qk_list, topk=10, local_attn_mask=None):
    assert batch_size == 1, "Only batch_size=1 supported for now"
    assert local_attn_mask is not None, "local_attn_mask must be provided"
    q_w, k_w = qk_list
    qk_list.clear()
    avgpool_q = torch.mean(q_w, dim=1) 
    avgpool_k = torch.mean(k_w, dim=1)
    del q_w, k_w
    avgpool_q = rearrange(avgpool_q, 's (h d) -> s h d', h=nheads)
    avgpool_k = rearrange(avgpool_k, 's (h d) -> s h d', h=nheads)
    q_heads = avgpool_q.permute(1, 0, 2)
    k_heads = avgpool_k.permute(1, 0, 2)
    D = avgpool_q.shape[-1]
    scores = torch.einsum("hld,hmd->hlm", q_heads, k_heads)
    scores.mul_(1 / math.sqrt(D))

    repeat_head = scores.shape[0]
    local_h, local_w = local_attn_mask.shape
    repeat_len = scores.shape[1] // local_h
    repeat_num = scores.shape[2] // local_w
    scores = scores.reshape(repeat_head, repeat_len, local_h, repeat_num, local_w)
    scores.masked_fill_(~local_attn_mask.view(1, 1, local_h, 1, local_w), -float('inf'))
    scores = scores.reshape(repeat_head, repeat_len * local_h, repeat_num * local_w)

    attn_map = torch.softmax(scores, dim=-1)
    del scores
    attn_map = rearrange(attn_map, 'h (it s1) s2 -> (h it) s1 s2', it=seqlen)
    loop_num, s1, s2 = attn_map.shape
    flat = attn_map.reshape(loop_num, -1)
    apply_topk = min(flat.shape[1]-1, topk)
    mask_new = _topk_threshold_mask(flat, apply_topk)
    del flat, attn_map
    mask_new = mask_new.reshape(nheads, seqlen * s1, s2)
    return mask_new.unsqueeze(0)


@torch.no_grad()
def generate_draft_block_mask_sage(batch_size, nheads, seqlen,
                                      qk_list, topk=10, local_attn_mask=None):
    assert batch_size == 1, "Only batch_size=1 supported for now"
    assert local_attn_mask is not None, "local_attn_mask must be provided"
    
    q_w, k_w = qk_list
    qk_list.clear()
    avgpool_q = torch.mean(q_w, dim=1) 
    del q_w
    avgpool_q = rearrange(avgpool_q, 's (h d) -> s h d', h=nheads)
    q_heads = avgpool_q.permute(1, 0, 2)
    D = avgpool_q.shape[-1]
    
    k_w_split = k_w.view(k_w.shape[0], 2, 64, k_w.shape[2])
    avgpool_k_split = torch.mean(k_w_split, dim=2)
    del k_w, k_w_split
    avgpool_k_refined = rearrange(avgpool_k_split, 's two d -> (s two) d', two=2) # shape: (s*2, C)
    avgpool_k_refined = rearrange(avgpool_k_refined, 's (h d) -> s h d', h=nheads) # shape: (s*2, h, d)
    k_heads_doubled = avgpool_k_refined.permute(1, 0, 2) # shape: (h, s*2, d)
    
    k_heads_1, k_heads_2 = torch.chunk(k_heads_doubled, 2, dim=1)
    scores_1 = torch.einsum("hld,hmd->hlm", q_heads, k_heads_1)
    scores_1.mul_(1 / math.sqrt(D))
    scores_2 = torch.einsum("hld,hmd->hlm", q_heads, k_heads_2)
    scores_2.mul_(1 / math.sqrt(D))
    scores = torch.cat([scores_1, scores_2], dim=-1)
    del scores_1, scores_2

    repeat_head = scores.shape[0]
    local_h, local_w = local_attn_mask.shape
    repeat_len = scores.shape[1] // local_h
    repeat_num = (scores.shape[2] // 2) // local_w
    scores = scores.reshape(repeat_head, repeat_len, local_h, repeat_num, local_w, 2)
    scores.masked_fill_(~local_attn_mask.view(1, 1, local_h, 1, local_w, 1), -float('inf'))
    scores = scores.reshape(repeat_head, repeat_len * local_h, repeat_num * local_w * 2)

    attn_map = torch.softmax(scores, dim=-1)
    del scores
    attn_map = rearrange(attn_map, 'h (it s1) s2 -> (h it) s1 s2', it=seqlen)
    loop_num, s1, s2 = attn_map.shape
    flat = attn_map.reshape(loop_num, -1)
    apply_topk = min(flat.shape[1]-1, topk)

    mask_new = _topk_threshold_mask(flat, apply_topk)
    del flat, attn_map
    mask_new = mask_new.reshape(loop_num, s1, s2)
    mask_new = mask_new.reshape(nheads, seqlen * s1, s2)
    mask_new = mask_new.to(torch.int8)
    return mask_new.unsqueeze(0)


# ----------------------------
# Attention kernels
# ----------------------------
def flash_attention(qkv_list: list[torch.Tensor], num_heads: int, compatibility_mode=False, attention_mask_list=None, return_KV=False):
    q, k, v = qkv_list
    qkv_list.clear()
    if isinstance(attention_mask_list, list):
        attention_mask = attention_mask_list[0]
        attention_mask_list.clear()
    else:
        attention_mask = None
    if attention_mask is not None:
        seqlen = q.shape[1]
        seqlen_kv = k.shape[1]
        if USE_BLOCK_ATTN and BLOCK_ATTN_AVAILABLE:
            q = rearrange(q, "b s (n d) -> (b s) n d", n=num_heads)
            k = rearrange(k, "b s (n d) -> (b s) n d", n=num_heads)
            v = rearrange(v, "b s (n d) -> (b s) n d", n=num_heads)
        else:
            q = rearrange(q, "b s (n d) -> b n s d", n=num_heads)
            k = rearrange(k, "b s (n d) -> b n s d", n=num_heads)
            v = rearrange(v, "b s (n d) -> b n s d", n=num_heads)
        max_seqlen_q_ = seqlen
        max_seqlen_k_ = seqlen_kv
        p_dropout = 0.0
        if USE_BLOCK_ATTN and BLOCK_ATTN_AVAILABLE:
            cu_seqlens_q = torch.tensor([0, seqlen], device=q.device, dtype=torch.int32)
            cu_seqlens_k = torch.tensor([0, seqlen_kv], device=q.device, dtype=torch.int32)
            head_mask_type = torch.tensor([1]*num_heads, device=q.device, dtype=torch.int32)
            streaming_info = None
            x = block_sparse_attn_func(
                q, k, v,
                cu_seqlens_q, cu_seqlens_k,
                head_mask_type,
                streaming_info,
                attention_mask,
                max_seqlen_q_, max_seqlen_k_,
                p_dropout,
                deterministic=False,
                softmax_scale=None,
                is_causal=False,
                exact_streaming=False,
                return_attn_probs=False,
            ).unsqueeze(0)
            x = rearrange(x, "b s n d -> b s (n d)", n=num_heads)
        else:
            qkv_list = [q, k, v]
            mask_list = [attention_mask]
            del q, k, v, attention_mask
            x = sparse_attention(qkv_list, mask_list, recycle_q=True)
            x = rearrange(x, "b n s d -> b s (n d)", n=num_heads)
    else:
        q = rearrange(q, "b s (n d) -> b s n d", n=num_heads)
        k = rearrange(k, "b s (n d) -> b s n d", n=num_heads)
        v = rearrange(v, "b s (n d) -> b s n d", n=num_heads)
        qkv_list = [q, k, v]
        del q, k, v
        x = pay_attention(qkv_list, force_attention="sdpa" if compatibility_mode else get_flashvsr_attention_mode(), recycle_q=True)
        x = rearrange(x, "b s n d -> b s (n d)", n=num_heads)
    return x


def modulate(x: torch.Tensor, shift: torch.Tensor, scale: torch.Tensor):
    return x.mul_(scale.add_(1)).add_(shift)


def sinusoidal_embedding_1d(dim, position):
    sinusoid = torch.outer(position.type(torch.float64), torch.pow(
        10000, -torch.arange(dim//2, dtype=torch.float64, device=position.device).div(dim//2)))
    x = torch.cat([torch.cos(sinusoid), torch.sin(sinusoid)], dim=1)
    return x.to(position.dtype)


def precompute_freqs_cis_3d(dim: int, end: int = 1024, theta: float = 10000.0):
    f_freqs_cis = precompute_freqs_cis(dim - 2 * (dim // 3), end, theta)
    h_freqs_cis = precompute_freqs_cis(dim // 3, end, theta)
    w_freqs_cis = precompute_freqs_cis(dim // 3, end, theta)
    return f_freqs_cis, h_freqs_cis, w_freqs_cis


def precompute_freqs_cis(dim: int, end: int = 1024, theta: float = 10000.0):
    freqs = 1.0 / (theta ** (torch.arange(0, dim, 2)
                   [: (dim // 2)].double() / dim))
    freqs = torch.outer(torch.arange(end, device=freqs.device), freqs)
    freqs_cis = torch.polar(torch.ones_like(freqs), freqs)
    return freqs_cis


def _rope_axis_inplace(x: torch.Tensor, cos: torch.Tensor, sin: torch.Tensor) -> None:
    x_even = x[..., 0::2]
    x_odd = x[..., 1::2]
    scratch = x_even.clone()
    x_even.mul_(cos).addcmul_(x_odd, sin, value=-1)
    x_odd.mul_(cos).addcmul_(scratch, sin)
    del scratch


def rope_apply(x_list, freqs, num_heads, f: int, h: int, w: int):
    x = x_list[0]
    x_list.clear()
    b = x.shape[0]
    x = x.view(b, f, h, w, num_heads, -1)
    f_freqs, h_freqs, w_freqs = freqs
    f_dim = f_freqs[0].shape[-1] * 2
    h_dim = h_freqs[0].shape[-1] * 2
    _rope_axis_inplace(x[..., :f_dim], f_freqs[0].view(1, f, 1, 1, 1, -1), f_freqs[1].view(1, f, 1, 1, 1, -1))
    _rope_axis_inplace(x[..., f_dim:f_dim + h_dim], h_freqs[0].view(1, 1, h, 1, 1, -1), h_freqs[1].view(1, 1, h, 1, 1, -1))
    _rope_axis_inplace(x[..., f_dim + h_dim:], w_freqs[0].view(1, 1, 1, w, 1, -1), w_freqs[1].view(1, 1, 1, w, 1, -1))
    return x.reshape(b, f * h * w, -1)


def rope_apply_windowed(x_list, freqs, num_heads, f: int, h: int, w: int, win: Tuple[int, int, int], batch_size: int):
    x = x_list[0]
    x_list.clear()
    wf, wh, ww = win
    nf, nh, nw = f // wf, h // wh, w // ww
    x = x.view(batch_size, nf, nh, nw, wf, wh, ww, num_heads, -1)
    f_freqs, h_freqs, w_freqs = freqs
    f_dim = f_freqs[0].shape[-1] * 2
    h_dim = h_freqs[0].shape[-1] * 2
    _rope_axis_inplace(x[..., :f_dim], f_freqs[0].view(nf, wf, -1).view(1, nf, 1, 1, wf, 1, 1, 1, -1), f_freqs[1].view(nf, wf, -1).view(1, nf, 1, 1, wf, 1, 1, 1, -1))
    _rope_axis_inplace(x[..., f_dim:f_dim + h_dim], h_freqs[0].view(nh, wh, -1).view(1, 1, nh, 1, 1, wh, 1, 1, -1), h_freqs[1].view(nh, wh, -1).view(1, 1, nh, 1, 1, wh, 1, 1, -1))
    _rope_axis_inplace(x[..., f_dim + h_dim:], w_freqs[0].view(nw, ww, -1).view(1, 1, 1, nw, 1, 1, ww, 1, -1), w_freqs[1].view(nw, ww, -1).view(1, 1, 1, nw, 1, 1, ww, 1, -1))
    return x.view(batch_size * nf * nh * nw, wf * wh * ww, -1)


# ----------------------------
# Norms & Blocks
# ----------------------------
def rms_norm_inplace(x: torch.Tensor | list[torch.Tensor], norm: nn.RMSNorm) -> torch.Tensor:
    if isinstance(x, list):
        x_list = x
        x = x_list[0]
        x_list.clear()
    inv_rms = torch.linalg.vector_norm(x, ord=2, dim=-1, keepdim=True, dtype=torch.float32)
    inv_rms.pow_(2).div_(x.shape[-1]).add_(norm.eps).rsqrt_()
    x.mul_(inv_rms.to(dtype=x.dtype))
    weight = norm.weight if norm.weight.dtype == x.dtype else norm.weight.to(dtype=x.dtype)
    x.mul_(weight)
    return x


class AttentionModule(nn.Module):
    def __init__(self, num_heads):
        super().__init__()
        self.num_heads = num_heads
        
    def forward(self, qkv_list, attention_mask_list=None):
        x = flash_attention(qkv_list, num_heads=self.num_heads, attention_mask_list=attention_mask_list)
        return x


class SelfAttention(nn.Module):
    def __init__(self, dim: int, num_heads: int, eps: float = 1e-6):
        super().__init__()
        self.dim = dim
        self.num_heads = num_heads
        self.head_dim = dim // num_heads

        self.q = nn.Linear(dim, dim)
        self.k = nn.Linear(dim, dim)
        self.v = nn.Linear(dim, dim)
        self.o = nn.Linear(dim, dim)
        self.norm_q = nn.RMSNorm(dim, eps=eps)
        self.norm_k = nn.RMSNorm(dim, eps=eps)
        
        self.attn = AttentionModule(self.num_heads)
        self.local_attn_mask = None

    def forward(self, x, freqs, f=None, h=None, w=None, local_num=None, topk=None,
                train_img=False, block_id=None, kv_len=None, is_full_block=False,
                is_stream=False, pre_cache_k=None, pre_cache_v=None, pre_cache_refs=None, local_range = 9, cache_next=True,
                allow_short_start=False):
        if isinstance(x, list):
            x_ref = x
            x = x_ref[0]
            x_ref.clear()
        if pre_cache_refs is not None:
            pre_cache_k, pre_cache_v = pre_cache_refs
        B, L, D = x.shape
        if is_stream and pre_cache_k is not None and pre_cache_v is not None:
            assert f==2, "f must be 2"
        if is_stream and (pre_cache_k is None or pre_cache_v is None):
            assert f==6 or (allow_short_start and f==2), " start f must be 6"
        assert L == f * h * w, "Sequence length mismatch with provided (f,h,w)."

        win = (2, 8, 8)
        x_w = WindowPartition3D.partition([x.view(B, f, h, w, D)], win)
        x = None

        v_w = self.v(x_w)

        q_w = self.q(x_w)        
        q_w = rms_norm_inplace(q_w, self.norm_q)
        q_list = [q_w]
        q_w = None
        q_w = rope_apply_windowed(q_list, freqs, self.num_heads, f, h, w, win, B)

        k_w = self.k(x_w)        
        del x_w
        k_w = rms_norm_inplace(k_w, self.norm_k)
        k_list = [k_w]
        k_w = None
        k_w = rope_apply_windowed(k_list, freqs, self.num_heads, f, h, w, win, B)

        seqlen = f//win[0]
        one_len = k_w.shape[0] // B // seqlen
        if pre_cache_k is not None and pre_cache_v is not None:
            k_w = torch.cat([pre_cache_k, k_w], dim=0)
            v_w = torch.cat([pre_cache_v, v_w], dim=0)
            if pre_cache_refs is not None:
                pre_cache_refs[0] = None
                pre_cache_refs[1] = None
            pre_cache_k = None
            pre_cache_v = None

        block_n = q_w.shape[0] // B
        block_s = q_w.shape[1]
        block_n_kv = k_w.shape[0] // B

        cache_k = cache_v = None
        if is_stream and cache_next:
            cache_blocks = min(block_n_kv, one_len * max(1, int(kv_len)))
            cache_k = k_w.view(B, block_n_kv, block_s, D)[:, -cache_blocks:].reshape(B * cache_blocks, block_s, D)
            cache_k = cache_k.detach().to("cpu")
            cache_v = v_w.view(B, block_n_kv, block_s, D)[:, -cache_blocks:].reshape(B * cache_blocks, block_s, D)
            cache_v = cache_v.detach().to("cpu")

        reorder_q = rearrange(q_w, '(b block_n) (block_s) d -> b (block_n block_s) d', block_n=block_n, block_s=block_s)
        reorder_k = rearrange(k_w, '(b block_n) (block_s) d -> b (block_n block_s) d', block_n=block_n_kv, block_s=block_s)
        reorder_v = rearrange(v_w, '(b block_n) (block_s) d -> b (block_n block_s) d', block_n=block_n_kv, block_s=block_s)

        del v_w

        window_size = win[0]*h*w//128

        if self.local_attn_mask is None or self.local_attn_mask_h!=h//8 or self.local_attn_mask_w!=w//8 or self.local_range!=local_range:
            self.local_attn_mask = build_local_block_mask_shifted_vec_normal_slide(h//8, w//8, local_range, local_range, include_self=True, device=k_w.device)
            self.local_attn_mask_h = h//8
            self.local_attn_mask_w = w//8
            self.local_range = local_range
        if USE_BLOCK_ATTN and BLOCK_ATTN_AVAILABLE:
            qk_list = [q_w, k_w]
            q_w = k_w = None
            attention_mask = generate_draft_block_mask(B, self.num_heads, seqlen, qk_list, topk=topk, local_attn_mask=self.local_attn_mask)
        else:
            qk_list = [q_w, k_w]
            q_w = k_w = None
            attention_mask = generate_draft_block_mask_sage(B, self.num_heads, seqlen, qk_list, topk=topk, local_attn_mask=self.local_attn_mask)
        qkv_list = [reorder_q, reorder_k, reorder_v]
        attention_mask_list = [attention_mask]
        del reorder_q, reorder_k, reorder_v, attention_mask
        x = self.attn(qkv_list, attention_mask_list)

        x = rearrange(x, 'b (block_n block_s) d -> (b block_n) (block_s) d', block_n=block_n, block_s=block_s)
        x = WindowPartition3D.reverse([x], win, (f, h, w))
        x = x.view(B, f*h*w, D)

        if is_stream:
            return self.o(x), cache_k, cache_v
        return self.o(x)


class CrossAttention(nn.Module):
    """
    仅考虑文本 context；提供持久 KV 缓存。
    """
    def __init__(self, dim: int, num_heads: int, eps: float = 1e-6):
        super().__init__()
        self.dim = dim
        self.num_heads = num_heads
        self.head_dim = dim // num_heads

        self.q = nn.Linear(dim, dim)
        self.k = nn.Linear(dim, dim)
        self.v = nn.Linear(dim, dim)
        self.o = nn.Linear(dim, dim)

        self.norm_q = nn.RMSNorm(dim, eps=eps)
        self.norm_k = nn.RMSNorm(dim, eps=eps)

        self.attn = AttentionModule(self.num_heads)

        # 持久缓存
        self.cache_k = None
        self.cache_v = None

    @torch.no_grad()
    def init_cache(self, ctx: torch.Tensor):
        """ctx: [B, S_ctx, dim] —— 经过 text_embedding 之后的上下文"""
        self.cache_k = rms_norm_inplace([self.k(ctx)], self.norm_k)
        self.cache_v = self.v(ctx)

    def clear_cache(self):
        self.cache_k = None
        self.cache_v = None

    def forward(self, x: torch.Tensor | list[torch.Tensor], y: torch.Tensor, is_stream: bool = False):
        """
        y 即文本上下文（未做其他分支）。
        """
        if isinstance(x, list):
            x_ref = x
            x = x_ref[0]
            x_ref.clear()
        q = rms_norm_inplace([self.q(x)], self.norm_q)
        del x
        assert self.cache_k is not None and self.cache_v is not None
        k = self.cache_k
        v = self.cache_v

        x = self.attn([q, k, v])
        return self.o(x)


class GateModule(nn.Module):
    def __init__(self,):
        super().__init__()

    def forward(self, x, gate, residual):
        return x.add_(residual.mul_(gate))


class DiTBlock(nn.Module):
    def __init__(self, dim: int, num_heads: int, ffn_dim: int, eps: float = 1e-6):
        super().__init__()
        self.dim = dim
        self.num_heads = num_heads
        self.ffn_dim = ffn_dim

        self.self_attn = SelfAttention(dim, num_heads, eps)
        self.cross_attn = CrossAttention(dim, num_heads, eps)

        self.norm1 = nn.LayerNorm(dim, eps=eps, elementwise_affine=False)
        self.norm2 = nn.LayerNorm(dim, eps=eps, elementwise_affine=False)
        self.norm3 = nn.LayerNorm(dim, eps=eps)
        self.ffn = nn.Sequential(nn.Linear(dim, ffn_dim), nn.GELU(
            approximate='tanh'), nn.Linear(ffn_dim, dim))
        self.modulation = nn.Parameter(torch.randn(1, 6, dim) / dim**0.5)
        self.gate = GateModule()

    def forward_ffn(self, x: torch.Tensor) -> torch.Tensor:
        chunk_size = max(1, min(x.shape[1], int(x.shape[1] * self.dim / self.ffn_dim)))
        if chunk_size >= x.shape[1]:
            return self.ffn(x)
        if self.training:
            return torch.cat([self.ffn(chunk) for chunk in x.split(chunk_size, dim=1)], dim=1)
        out = torch.empty_like(x)
        for start in range(0, x.shape[1], chunk_size):
            end = min(start + chunk_size, x.shape[1])
            out[:, start:end] = self.ffn(x[:, start:end])
        return out

    def forward(self, x, context, t_mod, freqs, f, h, w, local_num=None, topk=None,
                train_img=False, block_id=None, kv_len=None, is_full_block=False,
                is_stream=False, pre_cache_k=None, pre_cache_v=None, pre_cache_refs=None, local_range = 9, cache_next=True,
                allow_short_start=False):
        if isinstance(x, list):
            x_ref = x
            x = x_ref[0]
            x_ref.clear()
        shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp = (
            self.modulation.to(dtype=t_mod.dtype, device=t_mod.device) + t_mod).chunk(6, dim=1)
        input_x = modulate(self.norm1(x), shift_msa, scale_msa)
        x_list = [input_x] 
        input_x = None
        self_attn_output, self_attn_cache_k, self_attn_cache_v = self.self_attn(
            x_list , freqs, f, h, w, local_num, topk, train_img, block_id,
            kv_len=kv_len, is_full_block=is_full_block, is_stream=is_stream,
            pre_cache_k=pre_cache_k, pre_cache_v=pre_cache_v, pre_cache_refs=pre_cache_refs, local_range = local_range, cache_next=cache_next,
            allow_short_start=allow_short_start)

        x = self.gate(x, gate_msa, self_attn_output)
        del self_attn_output
        cross_input = self.norm3(x)
        cross = self.cross_attn([cross_input], context, is_stream=is_stream)
        x.add_(cross)
        del cross, cross_input
        input_x = modulate(self.norm2(x), shift_mlp, scale_mlp)
        ffn_out = self.forward_ffn(input_x)
        del input_x
        x = self.gate(x, gate_mlp, ffn_out)
        del ffn_out
        if is_stream:
            return x, self_attn_cache_k, self_attn_cache_v
        return x


class MLP(torch.nn.Module):
    def __init__(self, in_dim, out_dim, has_pos_emb=False):
        super().__init__()
        self.proj = torch.nn.Sequential(
            nn.LayerNorm(in_dim),
            nn.Linear(in_dim, in_dim),
            nn.GELU(),
            nn.Linear(in_dim, out_dim),
            nn.LayerNorm(out_dim)
        )
        self.has_pos_emb = has_pos_emb
        if has_pos_emb:
            self.emb_pos = torch.nn.Parameter(torch.zeros((1, 514, 1280)))

    def forward(self, x):
        if self.has_pos_emb:
            x.add_(self.emb_pos.to(dtype=x.dtype, device=x.device))
        return self.proj(x)


class Head(nn.Module):
    def __init__(self, dim: int, out_dim: int, patch_size: Tuple[int, int, int], eps: float):
        super().__init__()
        self.dim = dim
        self.patch_size = patch_size
        self.norm = nn.LayerNorm(dim, eps=eps, elementwise_affine=False)
        self.head = nn.Linear(dim, out_dim * math.prod(patch_size))
        self.modulation = nn.Parameter(torch.randn(1, 2, dim) / dim**0.5)

    def forward(self, x, t_mod):
        if isinstance(x, list):
            x_ref = x
            x = x_ref[0]
            x_ref.clear()
        shift, scale = (self.modulation.to(dtype=t_mod.dtype, device=t_mod.device) + t_mod).chunk(2, dim=1)
        x = modulate(self.norm(x), shift, scale)
        return self.head(x)


# ----------------------------
# WanModel (no image branch) — init 时即产生 KV 缓存
# ----------------------------
class WanModel(torch.nn.Module):
    def __init__(
        self,
        dim: int,
        in_dim: int,
        ffn_dim: int,
        out_dim: int,
        text_dim: int,
        freq_dim: int,
        eps: float,
        patch_size: Tuple[int, int, int],
        num_heads: int,
        num_layers: int,
        # init_context: torch.Tensor,     # <<<< 必填：在 __init__ 里用它生成 cross-attn KV 缓存
        has_image_input: bool = False,
    ):
        super().__init__()
        self.dim = dim
        self.freq_dim = freq_dim
        self.patch_size = patch_size

        # patch embed
        self.patch_embedding = nn.Conv3d(
            in_dim, dim, kernel_size=patch_size, stride=patch_size)

        # text / time embed
        self.text_embedding = nn.Sequential(
            nn.Linear(text_dim, dim),
            nn.GELU(approximate='tanh'),
            nn.Linear(dim, dim)
        )
        self.time_embedding = nn.Sequential(
            nn.Linear(freq_dim, dim),
            nn.SiLU(),
            nn.Linear(dim, dim)
        )
        self.time_projection = nn.Sequential(
            nn.SiLU(), nn.Linear(dim, dim * 6))

        # blocks
        self.blocks = nn.ModuleList([
            DiTBlock(dim, num_heads, ffn_dim, eps)
            for _ in range(num_layers)
        ])
        self.head = Head(dim, out_dim, patch_size, eps)

        head_dim = dim // num_heads
        self.freqs = precompute_freqs_cis_3d(head_dim)

        self._cross_kv_initialized = False

    # 可选:手动清空 / 重新初始化
    def clear_cross_kv(self):
        for blk in self.blocks:
            blk.cross_attn.clear_cache()
        self._cross_kv_initialized = False

    @torch.no_grad()
    def reinit_cross_kv(self, new_context: torch.Tensor):
        ctx_txt = self.text_embedding(new_context)
        for blk in self.blocks:
            blk.cross_attn.init_cache(ctx_txt)
        self._cross_kv_initialized = True

    def patchify(self, x: torch.Tensor):
        x = self.patch_embedding(x)
        grid_size = x.shape[2:]
        x = rearrange(x, 'b c f h w -> b (f h w) c').contiguous()
        return x, grid_size  # x, grid_size: (f, h, w)

    def unpatchify(self, x: torch.Tensor | list[torch.Tensor], grid_size: torch.Tensor):
        if isinstance(x, list):
            x_ref = x
            x = x_ref[0]
            x_ref.clear()
        return rearrange(
            x, 'b (f h w) (x y z c) -> b c (f x) (h y) (w z)',
            f=grid_size[0], h=grid_size[1], w=grid_size[2], 
            x=self.patch_size[0], y=self.patch_size[1], z=self.patch_size[2]
        )

    def forward(self,
                x: torch.Tensor,
                timestep: torch.Tensor,
                context: torch.Tensor,
                use_gradient_checkpointing: bool = False,
                use_gradient_checkpointing_offload: bool = False,
                LQ_latents: Optional[List[torch.Tensor]] = None,
                train_img: bool = False,
                topk_ratio: Optional[float] = None,
                kv_ratio: Optional[float] = None,
                local_num: Optional[int] = None,
                is_full_block: bool = False,
                causal_idx: Optional[int] = None,
                **kwargs,
                ):
        # time / text embeds
        t = self.time_embedding(
            sinusoidal_embedding_1d(self.freq_dim, timestep))
        t_mod = self.time_projection(t).unflatten(1, (6, self.dim))

        # 这里仍会嵌入 text（CrossAttention 若已有缓存会忽略它）
        # context = self.text_embedding(context)

        # 输入打补丁
        x, (f, h, w) = self.patchify(x)
        B = x.shape[0]

        # window / masks 超参
        win = (2, 8, 8)
        seqlen = f//win[0]
        if local_num is None:
            local_random = random.random()
            if local_random < 0.3:
                local_num = seqlen - 3
            elif local_random < 0.4:
                local_num = seqlen - 4
            elif local_random < 0.5:
                local_num = seqlen - 2
            else:
                local_num = seqlen

        window_size = win[0]*h*w//128
        square_num = window_size*window_size
        topk_ratio = 2.0
        topk = min(max(int(square_num*topk_ratio), 1), int(square_num*seqlen)-1)

        if kv_ratio is None:
            kv_ratio = (random.uniform(0., 1.0)**2)*(local_num-2-2)+2
        kv_len = min(max(int(window_size*kv_ratio), 1), int(window_size*seqlen)-1)

        decay_ratio = random.uniform(0.7, 1.0)

        freqs = tuple((freq.real.to(device=x.device, dtype=x.dtype), freq.imag.to(device=x.device, dtype=x.dtype)) for freq in (self.freqs[0][:f], self.freqs[1][:h], self.freqs[2][:w]))

        def create_custom_forward(module):
            def custom_forward(*inputs):
                return module(*inputs)
            return custom_forward

        # blocks
        for block_id, block in enumerate(self.blocks):
            if LQ_latents is not None and block_id < len(LQ_latents):
                x.add_(LQ_latents[block_id])

            if self.training and use_gradient_checkpointing:
                if use_gradient_checkpointing_offload:
                    with torch.autograd.graph.save_on_cpu():
                        x = torch.utils.checkpoint.checkpoint(
                            create_custom_forward(block),
                            x, context, t_mod, freqs, f, h, w, local_num, topk,
                            train_img, block_id, kv_len, is_full_block, False,
                            None, None,
                            use_reentrant=False,
                        )
                else:
                    x = torch.utils.checkpoint.checkpoint(
                        create_custom_forward(block),
                        x, context, t_mod, freqs, f, h, w, local_num, topk,
                        train_img, block_id, kv_len, is_full_block, False,
                        None, None, 
                        use_reentrant=False,
                    )
            else:
                x = block([x], context, t_mod, freqs, f, h, w, local_num, topk,
                          train_img, block_id, kv_len, is_full_block, False,
                          None, None)

        x = self.head([x], t)
        x = self.unpatchify([x], (f, h, w))
        return x

    @staticmethod
    def state_dict_converter():
        return WanModelStateDictConverter()
    

# ----------------------------
# State dict converter（保持原映射；已忽略 has_image_input 使用）
# ----------------------------
class WanModelStateDictConverter:
    def __init__(self):
        pass
    
    def from_civitai(self, state_dict):
        state_dict = {name: param for name, param in state_dict.items() if not name.startswith("vace")}
        # 保留原有哈希匹配返回的 config；实现本身不使用 has_image_input 分支
        if hash_state_dict_keys(state_dict) == "9269f8db9040a9d860eaca435be61814":
            config = {"has_image_input": False,"patch_size": [1, 2, 2],"in_dim": 16,"dim": 1536,"ffn_dim": 8960,"freq_dim": 256,"text_dim": 4096,"out_dim": 16,"num_heads": 12,"num_layers": 30,"eps": 1e-6}
        elif hash_state_dict_keys(state_dict) == "aafcfd9672c3a2456dc46e1cb6e52c70":
            config = {"has_image_input": False,"patch_size": [1, 2, 2],"in_dim": 16,"dim": 5120,"ffn_dim": 13824,"freq_dim": 256,"text_dim": 4096,"out_dim": 16,"num_heads": 40,"num_layers": 40,"eps": 1e-6}
        elif hash_state_dict_keys(state_dict) == "6bfcfb3b342cb286ce886889d519a77e":
            config = {"has_image_input": False,"patch_size": [1, 2, 2],"in_dim": 36,"dim": 5120,"ffn_dim": 13824,"freq_dim": 256,"text_dim": 4096,"out_dim": 16,"num_heads": 40,"num_layers": 40,"eps": 1e-6}
        elif hash_state_dict_keys(state_dict) == "6d6ccde6845b95ad9114ab993d917893":
            config = {"has_image_input": False,"patch_size": [1, 2, 2],"in_dim": 36,"dim": 1536,"ffn_dim": 8960,"freq_dim": 256,"text_dim": 4096,"out_dim": 16,"num_heads": 12,"num_layers": 30,"eps": 1e-6}
        elif hash_state_dict_keys(state_dict) == "349723183fc063b2bfc10bb2835cf677":
            config = {"has_image_input": False,"patch_size": [1, 2, 2],"in_dim": 48,"dim": 1536,"ffn_dim": 8960,"freq_dim": 256,"text_dim": 4096,"out_dim": 16,"num_heads": 12,"num_layers": 30,"eps": 1e-6}
        elif hash_state_dict_keys(state_dict) == "efa44cddf936c70abd0ea28b6cbe946c":
            config = {"has_image_input": False,"patch_size": [1, 2, 2],"in_dim": 48,"dim": 5120,"ffn_dim": 13824,"freq_dim": 256,"text_dim": 4096,"out_dim": 16,"num_heads": 40,"num_layers": 40,"eps": 1e-6}
        elif hash_state_dict_keys(state_dict) == "3ef3b1f8e1dab83d5b71fd7b617f859f":
            config = {"has_image_input": False,"patch_size": [1, 2, 2],"in_dim": 36,"dim": 5120,"ffn_dim": 13824,"freq_dim": 256,"text_dim": 4096,"out_dim": 16,"num_heads": 40,"num_layers": 40,"eps": 1e-6,"has_image_pos_emb": False}
        else:
            config = {}
        return state_dict, config