# coding=utf-8
# @Author  : Saurabhchand Bhati
# @Affiliation  : Massachusetts Institute of Technology
# VMamba backbone is from https://github.com/MzeroMiko/VMamba/blob/main/vmamba.py
# VMambaLayer, VMambaModel, VMambaForImageClassification are implemnted based on VMamba
# SS2Dv0, SS2Dv1, SS2S are merged into one class and initiliazation is limited to v05_noz,
# patch embeddings is limited to v2 and downsample is limited to v3.

# MIT License

# Copyright (c) 2024 MzeroMiko, Saurabhchand Bhati

# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

"""VMamba: Visual State Space Model configuration model"""

import math
import torch 
import warnings
import torch.nn as nn
import torch.nn.functional as F
import torch.utils.checkpoint as checkpoint
from timm.models.layers import DropPath, trunc_normal_
from functools import partial
from typing import Optional, Callable, Any, Union
from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss
from transformers.modeling_outputs import ImageClassifierOutput

from transformers.utils import logging
from transformers.modeling_utils import PreTrainedModel

from .configuration_vmamba import VMambaConfig

logger = logging.get_logger(__name__)

# General docstring
_CONFIG_FOR_DOC = "VMambaConfig"

WITH_TRITON = True
# WITH_TRITON = False
try:
    import triton
    import triton.language as tl
except:
    WITH_TRITON = False
    warnings.warn("Triton not installed, fall back to pytorch implements.")

# to make sure cached_property can be loaded for triton
if WITH_TRITON:
    try:
        from functools import cached_property
    except:
        warnings.warn("if you are using py37, add this line to functools.py: "
            "cached_property = lambda func: property(lru_cache()(func))")

# torch implementation ========================================
def cross_scan_fwd(x: torch.Tensor, in_channel_first=True, out_channel_first=True, scans=0):
    if in_channel_first:
        B, C, H, W = x.shape
        if scans == 0:
            y = x.new_empty((B, 4, C, H * W))
            y[:, 0, :, :] = x.flatten(2, 3)
            y[:, 1, :, :] = x.transpose(dim0=2, dim1=3).flatten(2, 3)
            y[:, 2:4, :, :] = torch.flip(y[:, 0:2, :, :], dims=[-1])
        elif scans == 1:
            y = x.view(B, 1, C, H * W).repeat(1, 4, 1, 1)
        elif scans == 2:
            y = x.view(B, 1, C, H * W).repeat(1, 2, 1, 1)
            y = torch.cat([y, y.flip(dims=[-1])], dim=1)
        elif scans == 3:
            y = x.new_empty((B, 4, C, H * W))
            y[:, 0, :, :] = x.flatten(2, 3)
            y[:, 1, :, :] = torch.rot90(x, 1, dims=(2, 3)).flatten(2, 3)
            y[:, 2, :, :] = torch.rot90(x, 2, dims=(2, 3)).flatten(2, 3)
            y[:, 3, :, :] = torch.rot90(x, 3, dims=(2, 3)).flatten(2, 3)
    else:
        B, H, W, C = x.shape
        if scans == 0:
            y = x.new_empty((B, H * W, 4, C))
            y[:, :, 0, :] = x.flatten(1, 2)
            y[:, :, 1, :] = x.transpose(dim0=1, dim1=2).flatten(1, 2)
            y[:, :, 2:4, :] = torch.flip(y[:, :, 0:2, :], dims=[1])
        elif scans == 1:
            y = x.view(B, H * W, 1, C).repeat(1, 1, 4, 1)
        elif scans == 2:
            y = x.view(B, H * W, 1, C).repeat(1, 1, 2, 1)
            y = torch.cat([y, y.flip(dims=[1])], dim=2)
        elif scans == 3:
            y = x.new_empty((B, H * W, 4, C))
            y[:, :, 0, :] = x.flatten(1, 2)
            y[:, :, 1, :] = torch.rot90(x, 1, dims=(1, 2)).flatten(1, 2)
            y[:, :, 2, :] = torch.rot90(x, 2, dims=(1, 2)).flatten(1, 2)
            y[:, :, 3, :] = torch.rot90(x, 3, dims=(1, 2)).flatten(1, 2)

    if in_channel_first and (not out_channel_first):
        y = y.permute(0, 3, 1, 2).contiguous()
    elif (not in_channel_first) and out_channel_first:
        y = y.permute(0, 2, 3, 1).contiguous()

    return y


def cross_merge_fwd(y: torch.Tensor, in_channel_first=True, out_channel_first=True, scans=0):
    if out_channel_first:
        B, K, D, H, W = y.shape
        y = y.view(B, K, D, -1)
        if scans == 0:
            y = y[:, 0:2] + y[:, 2:4].flip(dims=[-1]).view(B, 2, D, -1)
            y = y[:, 0] + y[:, 1].view(B, -1, W, H).transpose(dim0=2, dim1=3).contiguous().view(B, D, -1)
        elif scans == 1:
            y = y.sum(1)
        elif scans == 2:
            y = y[:, 0:2] + y[:, 2:4].flip(dims=[-1]).view(B, 2, D, -1)
            y = y.sum(1)
        elif scans == 3:
            oy = y[:, 0, :, :].contiguous().view(B, D, -1)
            oy = oy + torch.rot90(y.view(B, K, D, W, H)[:, 1, :, :, :], -1, dims=(2, 3)).flatten(2, 3)
            oy = oy + torch.rot90(y.view(B, K, D, H, W)[:, 2, :, :, :], -2, dims=(2, 3)).flatten(2, 3)
            oy = oy + torch.rot90(y.view(B, K, D, W, H)[:, 3, :, :, :], -3, dims=(2, 3)).flatten(2, 3)
            y = oy
    else:
        B, H, W, K, D = y.shape
        y = y.view(B, -1, K, D)
        if scans == 0:
            y = y[:, :, 0:2] + y[:, :, 2:4].flip(dims=[1]).view(B, -1, 2, D)
            y = y[:, :, 0] + y[:, :, 1].view(B, W, H, -1).transpose(dim0=1, dim1=2).contiguous().view(B, -1, D)        
        elif scans == 1:
            y = y.sum(2)
        elif scans == 2:
            y = y[:, :, 0:2] + y[:, :, 2:4].flip(dims=[1]).view(B, -1, 2, D)
            y = y.sum(2)
        elif scans == 3:
            oy = y[:, :, 0, :].contiguous().view(B, -1, D)
            oy = oy + torch.rot90(y.view(B, W, H, K, D)[:, :, :, 1, :], -1, dims=(1, 2)).flatten(1, 2)
            oy = oy + torch.rot90(y.view(B, H, W, K, D)[:, :, :, 2, :], -2, dims=(1, 2)).flatten(1, 2)
            oy = oy + torch.rot90(y.view(B, W, H, K, D)[:, :, :, 3, :], -3, dims=(1, 2)).flatten(1, 2)
            y = oy
            
    if in_channel_first and (not out_channel_first):
        y = y.permute(0, 2, 1).contiguous()
    elif (not in_channel_first) and out_channel_first:
        y = y.permute(0, 2, 1).contiguous()
    
    return y


def cross_scan1b1_fwd(x: torch.Tensor, in_channel_first=True, out_channel_first=True, scans=0):
    if in_channel_first:
        B, _, C, H, W = x.shape
        if scans == 0:
            y = torch.stack([
                x[:, 0].flatten(2, 3),
                x[:, 1].transpose(dim0=2, dim1=3).flatten(2, 3),
                torch.flip(x[:, 2].flatten(2, 3), dims=[-1]),
                torch.flip(x[:, 3].transpose(dim0=2, dim1=3).flatten(2, 3), dims=[-1]),
            ], dim=1)
        elif scans == 1:
            y = x.flatten(2, 3)
        elif scans == 2:
            y = torch.stack([
                x[:, 0].flatten(2, 3),
                x[:, 1].flatten(2, 3),
                torch.flip(x[:, 2].flatten(2, 3), dims=[-1]),
                torch.flip(x[:, 3].flatten(2, 3), dims=[-1]),
            ], dim=1)
        elif scans == 3:
            y = torch.stack([
                x[:, 0, :, :, :].flatten(2, 3),
                torch.rot90(x[:, 1, :, :, :], 1, dims=(2, 3)).flatten(2, 3),
                torch.rot90(x[:, 2, :, :, :], 2, dims=(2, 3)).flatten(2, 3),
                torch.rot90(x[:, 3, :, :, :], 3, dims=(2, 3)).flatten(2, 3),
            ], dim=1)

    else:
        B, H, W, _, C = x.shape
        if scans == 0:
            y = torch.stack([
                x[:, :, :, 0].flatten(1, 2),
                x[:, :, :, 1].transpose(dim0=1, dim1=2).flatten(1, 2),
                torch.flip(x[:, :, :, 2].flatten(1, 2), dims=[1]),
                torch.flip(x[:, :, :, 3].transpose(dim0=1, dim1=2).flatten(1, 2), dims=[1]),
            ], dim=2)
        elif scans == 1:
            y = x.flatten(1, 2)
        elif scans == 2:
            y = torch.stack([
                x[:, 0].flatten(1, 2),
                x[:, 1].flatten(1, 2),
                torch.flip(x[:, 2].flatten(1, 2), dims=[-1]),
                torch.flip(x[:, 3].flatten(1, 2), dims=[-1]),
            ], dim=2)
        elif scans == 3:
            y = torch.stack([
                x[:, :, :, 0, :].flatten(1, 2),
                torch.rot90(x[:, :, :, 1, :], 1, dims=(1, 2)).flatten(1, 2),
                torch.rot90(x[:, :, :, 2, :], 2, dims=(1, 2)).flatten(1, 2),
                torch.rot90(x[:, :, :, 3, :], 3, dims=(1, 2)).flatten(1, 2),
            ], dim=1)

    if in_channel_first and (not out_channel_first):
        y = y.permute(0, 3, 1, 2).contiguous()
    elif (not in_channel_first) and out_channel_first:
        y = y.permute(0, 2, 3, 1).contiguous()

    return y


def cross_merge1b1_fwd(y: torch.Tensor, in_channel_first=True, out_channel_first=True, scans=0):
    if out_channel_first:
        B, K, D, H, W = y.shape
        y = y.view(B, K, D, -1)
        if scans == 0:
            y = torch.stack([
                y[:, 0],
                y[:, 1].view(B, -1, W, H).transpose(dim0=2, dim1=3).flatten(2, 3),
                torch.flip(y[:, 2], dims=[-1]),
                torch.flip(y[:, 3].view(B, -1, W, H).transpose(dim0=2, dim1=3).flatten(2, 3), dims=[-1]),
            ], dim=1)
        elif scans == 1:
            y = y
        elif scans == 2:
            y = torch.stack([
                y[:, 0],
                y[:, 1],
                torch.flip(y[:, 2], dims=[-1]),
                torch.flip(y[:, 3], dims=[-1]),
            ], dim=1)
        elif scans == 3:
            y = torch.stack([
                y[:, 0, :, :].contiguous().view(B, D, -1),
                torch.rot90(y.view(B, K, D, W, H)[:, 1, :, :, :], -1, dims=(2, 3)).flatten(2, 3),
                torch.rot90(y.view(B, K, D, H, W)[:, 2, :, :, :], -2, dims=(2, 3)).flatten(2, 3),
                torch.rot90(y.view(B, K, D, W, H)[:, 3, :, :, :], -3, dims=(2, 3)).flatten(2, 3),
            ], dim=1)
    else:
        B, H, W, K, D = y.shape
        y = y.view(B, -1, K, D)
        if scans == 0:
            y = torch.stack([
                y[:, :, 0],
                y[:, :, 1].view(B, W, H, -1).transpose(dim0=1, dim1=2).flatten(1, 2),
                torch.flip(y[:, :, 2], dims=[1]),
                torch.flip(y[:, :, 3].view(B, W, H, -1).transpose(dim0=1, dim1=2).flatten(1, 2), dims=[1]),
            ], dim=2)
        elif scans == 1:
            y = y
        elif scans == 2:
            y = torch.stack([
                y[:, :, 0],
                y[:, :, 1],
                torch.flip(y[:, :, 2], dims=[1]),
                torch.flip(y[:, :, 3], dims=[1]),
            ], dim=2)
        elif scans == 3:
            y = torch.stack([
                y[:, :, 0, :].contiguous().view(B, -1, D),
                torch.rot90(y.view(B, W, H, K, D)[:, :, :, 1, :], -1, dims=(1, 2)).flatten(1, 2),
                torch.rot90(y.view(B, H, W, K, D)[:, :, :, 2, :], -2, dims=(1, 2)).flatten(1, 2),
                torch.rot90(y.view(B, W, H, K, D)[:, :, :, 3, :], -3, dims=(1, 2)).flatten(1, 2),
            ], dim=2)

    if out_channel_first and (not in_channel_first):
        y = y.permute(0, 3, 1, 2).contiguous()
    elif (not out_channel_first) and in_channel_first:
        y = y.permute(0, 2, 3, 1).contiguous()

    return y


class CrossScanF(torch.autograd.Function):
    @staticmethod
    def forward(ctx, x: torch.Tensor, in_channel_first=True, out_channel_first=True, one_by_one=False, scans=0):
        # x: (B, C, H, W) | (B, H, W, C) | (B, 4, C, H, W) | (B, H, W, 4, C)
        # y: (B, 4, C, H * W) | (B, H * W, 4, C)
        ctx.in_channel_first = in_channel_first
        ctx.out_channel_first = out_channel_first
        ctx.one_by_one = one_by_one
        ctx.scans = scans

        if one_by_one:
            B, K, C, H, W = x.shape
            if not in_channel_first:
                B, H, W, K, C = x.shape
        else:
            B, C, H, W = x.shape
            if not in_channel_first:
                B, H, W, C = x.shape
        ctx.shape = (B, C, H, W)

        _fn = cross_scan1b1_fwd if one_by_one else cross_scan_fwd
        y = _fn(x, in_channel_first, out_channel_first, scans)

        return y
    
    @staticmethod
    def backward(ctx, ys: torch.Tensor):
        # out: (b, k, d, l)
        in_channel_first = ctx.in_channel_first
        out_channel_first = ctx.out_channel_first
        one_by_one = ctx.one_by_one
        scans = ctx.scans
        B, C, H, W = ctx.shape

        ys = ys.view(B, -1, C, H, W) if out_channel_first else ys.view(B, H, W, -1, C)
        _fn = cross_merge1b1_fwd if one_by_one else cross_merge_fwd
        y = _fn(ys, in_channel_first, out_channel_first, scans)
        
        if one_by_one:
            y = y.view(B, 4, -1, H, W) if in_channel_first else y.view(B, H, W, 4, -1)
        else:
            y = y.view(B, -1, H, W) if in_channel_first else y.view(B, H, W, -1)

        return y, None, None, None, None


class CrossMergeF(torch.autograd.Function):
    @staticmethod
    def forward(ctx, ys: torch.Tensor, in_channel_first=True, out_channel_first=True, one_by_one=False, scans=0):
        # x: (B, C, H, W) | (B, H, W, C) | (B, 4, C, H, W) | (B, H, W, 4, C)
        # y: (B, 4, C, H * W) | (B, H * W, 4, C)
        ctx.in_channel_first = in_channel_first
        ctx.out_channel_first = out_channel_first
        ctx.one_by_one = one_by_one
        ctx.scans = scans

        B, K, C, H, W = ys.shape
        if not out_channel_first:
            B, H, W, K, C = ys.shape
        ctx.shape = (B, C, H, W)
        
        _fn = cross_merge1b1_fwd if one_by_one else cross_merge_fwd
        y = _fn(ys, in_channel_first, out_channel_first, scans)

        return y
    
    @staticmethod
    def backward(ctx, x: torch.Tensor):
        # B, D, L = x.shape
        # out: (b, k, d, h, w)
        in_channel_first = ctx.in_channel_first
        out_channel_first = ctx.out_channel_first
        one_by_one = ctx.one_by_one
        scans = ctx.scans
        B, C, H, W = ctx.shape
    
        if not one_by_one:
            if in_channel_first:
                x = x.view(B, C, H, W)
            else:
                x = x.view(B, H, W, C)
        else:
            if in_channel_first:
                x = x.view(B, 4, C, H, W)
            else:
                x = x.view(B, H, W, 4, C)   
                     
        _fn = cross_scan1b1_fwd if one_by_one else cross_scan_fwd
        x = _fn(x, in_channel_first, out_channel_first, scans)
        x = x.view(B, 4, C, H, W) if out_channel_first else x.view(B, H, W, 4, C)
    
        return x, None, None, None, None


# triton implements ========================================

@triton.jit
def triton_cross_scan_flex(
    x: tl.tensor, # (B, C, H, W) | (B, H, W, C) | (B, 4, C, H, W) | (B, H, W, 4, C)
    y: tl.tensor, # (B, 4, C, H, W) | (B, H, W, 4, C)
    x_layout: tl.constexpr,
    y_layout: tl.constexpr,
    operation: tl.constexpr,
    onebyone: tl.constexpr,
    scans: tl.constexpr,
    BC: tl.constexpr,
    BH: tl.constexpr,
    BW: tl.constexpr,
    DC: tl.constexpr,
    DH: tl.constexpr,
    DW: tl.constexpr,
    NH: tl.constexpr,
    NW: tl.constexpr,
):
    # x_layout = 0
    # y_layout = 1 # 0 BCHW, 1 BHWC
    # operation = 0 # 0 scan, 1 merge
    # onebyone = 0 # 0 false, 1 true
    # scans = 0 # 0 cross scan, 1 unidirectional, 2 bidirectional

    i_hw, i_c, i_b = tl.program_id(0), tl.program_id(1), tl.program_id(2)
    i_h, i_w = (i_hw // NW), (i_hw % NW)
    _mask_h = (i_h * BH + tl.arange(0, BH)) < DH
    _mask_w = (i_w * BW + tl.arange(0, BW)) < DW
    _mask_hw = _mask_h[:, None] & _mask_w[None, :]
    _for_C = min(DC - i_c * BC, BC)

    pos_h = (i_h * BH + tl.arange(0, BH)[:, None])
    pos_w = (i_w * BW + tl.arange(0, BW)[None, :])
    neg_h = (DH - i_h * BH - 1 - tl.arange(0, BH)[:, None])
    neg_w = (DW - i_w * BW - 1 - tl.arange(0, BW)[None, :])
    if scans == 0:
        # none; trans; flip; trans + flip;
        HWRoute0 = pos_h * DW + pos_w
        HWRoute1 = pos_w * DH + pos_h # trans
        HWRoute2 = neg_h * DW + neg_w # flip
        HWRoute3 = neg_w * DH + neg_h # trans + flip
    elif scans == 1:
        # none; none; none; none;
        HWRoute0 = pos_h * DW + pos_w
        HWRoute1 = HWRoute0
        HWRoute2 = HWRoute0
        HWRoute3 = HWRoute0
    elif scans == 2:
        # none; none; flip; flip;
        HWRoute0 = pos_h * DW + pos_w
        HWRoute1 = HWRoute0
        HWRoute2 = neg_h * DW + neg_w # flip
        HWRoute3 = HWRoute2 
    elif scans == 3:
        # none; rot90; rot180==flip; rot270;
        HWRoute0 = pos_h * DW + pos_w
        HWRoute1 = neg_w * DH + pos_h
        HWRoute2 = neg_h * DW + neg_w
        HWRoute3 = pos_w * DH + neg_h

    _tmp1 = DC * DH * DW

    y_ptr_base = y + i_b * 4 * _tmp1 + (i_c * BC * DH * DW if y_layout == 0 else i_c * BC)
    if y_layout == 0:
        p_y1 = y_ptr_base + HWRoute0
        p_y2 = y_ptr_base + _tmp1 + HWRoute1
        p_y3 = y_ptr_base + 2 * _tmp1 + HWRoute2
        p_y4 = y_ptr_base + 3 * _tmp1 + HWRoute3
    else:
        p_y1 = y_ptr_base + HWRoute0 * 4 * DC
        p_y2 = y_ptr_base + DC + HWRoute1 * 4 * DC
        p_y3 = y_ptr_base + 2 * DC + HWRoute2 * 4 * DC
        p_y4 = y_ptr_base + 3 * DC + HWRoute3 * 4 * DC       
    
    if onebyone == 0:
        x_ptr_base = x + i_b * _tmp1 + (i_c * BC * DH * DW if x_layout == 0 else i_c * BC)
        if x_layout == 0:
            p_x = x_ptr_base + HWRoute0
        else:
            p_x = x_ptr_base + HWRoute0 * DC

        if operation == 0:
            for idxc in range(_for_C):
                _idx_x = idxc * DH * DW if x_layout == 0 else idxc
                _idx_y = idxc * DH * DW if y_layout == 0 else idxc
                _x = tl.load(p_x + _idx_x, mask=_mask_hw)
                tl.store(p_y1 + _idx_y, _x, mask=_mask_hw)
                tl.store(p_y2 + _idx_y, _x, mask=_mask_hw)
                tl.store(p_y3 + _idx_y, _x, mask=_mask_hw)
                tl.store(p_y4 + _idx_y, _x, mask=_mask_hw)
        elif operation == 1:
            for idxc in range(_for_C):
                _idx_x = idxc * DH * DW if x_layout == 0 else idxc
                _idx_y = idxc * DH * DW if y_layout == 0 else idxc
                _y1 = tl.load(p_y1 + _idx_y, mask=_mask_hw)
                _y2 = tl.load(p_y2 + _idx_y, mask=_mask_hw)
                _y3 = tl.load(p_y3 + _idx_y, mask=_mask_hw)
                _y4 = tl.load(p_y4 + _idx_y, mask=_mask_hw)
                tl.store(p_x + _idx_x, _y1 + _y2 + _y3 + _y4, mask=_mask_hw)

    else:
        x_ptr_base = x + i_b * 4 * _tmp1 + (i_c * BC * DH * DW if x_layout == 0 else i_c * BC)
        if x_layout == 0:
            p_x1 = x_ptr_base + HWRoute0
            p_x2 = p_x1 + _tmp1
            p_x3 = p_x2 + _tmp1
            p_x4 = p_x3 + _tmp1  
        else:
            p_x1 = x_ptr_base + HWRoute0 * 4 * DC
            p_x2 = p_x1 + DC
            p_x3 = p_x2 + DC
            p_x4 = p_x3 + DC        
    
        if operation == 0:
            for idxc in range(_for_C):
                _idx_x = idxc * DH * DW if x_layout == 0 else idxc
                _idx_y = idxc * DH * DW if y_layout == 0 else idxc
                tl.store(p_y1 + _idx_y, tl.load(p_x1 + _idx_x, mask=_mask_hw), mask=_mask_hw)
                tl.store(p_y2 + _idx_y, tl.load(p_x2 + _idx_x, mask=_mask_hw), mask=_mask_hw)
                tl.store(p_y3 + _idx_y, tl.load(p_x3 + _idx_x, mask=_mask_hw), mask=_mask_hw)
                tl.store(p_y4 + _idx_y, tl.load(p_x4 + _idx_x, mask=_mask_hw), mask=_mask_hw)
        else:
            for idxc in range(_for_C):
                _idx_x = idxc * DH * DW if x_layout == 0 else idxc
                _idx_y = idxc * DH * DW if y_layout == 0 else idxc
                tl.store(p_x1 + _idx_x, tl.load(p_y1 + _idx_y), mask=_mask_hw)
                tl.store(p_x2 + _idx_x, tl.load(p_y2 + _idx_y), mask=_mask_hw)
                tl.store(p_x3 + _idx_x, tl.load(p_y3 + _idx_y), mask=_mask_hw)
                tl.store(p_x4 + _idx_x, tl.load(p_y4 + _idx_y), mask=_mask_hw)


class CrossScanTritonF(torch.autograd.Function):
    @staticmethod
    def forward(ctx, x: torch.Tensor, in_channel_first=True, out_channel_first=True, one_by_one=False, scans=0):
        if one_by_one:
            if in_channel_first:
                B, _, C, H, W = x.shape
            else:
                B, H, W, _, C = x.shape
        else:
            if in_channel_first:
                B, C, H, W = x.shape
            else:
                B, H, W, C = x.shape
        B, C, H, W = int(B), int(C), int(H), int(W)
        BC, BH, BW = 1, 32, 32
        NH, NW, NC = triton.cdiv(H, BH), triton.cdiv(W, BW), triton.cdiv(C, BC)
        
        ctx.in_channel_first = in_channel_first
        ctx.out_channel_first = out_channel_first
        ctx.one_by_one = one_by_one
        ctx.scans = scans
        ctx.shape = (B, C, H, W)
        ctx.triton_shape = (BC, BH, BW, NC, NH, NW)

        y = x.new_empty((B, 4, C, H * W)) if out_channel_first else x.new_empty((B, H * W, 4, C))
        triton_cross_scan_flex[(NH * NW, NC, B)](
            x.contiguous(), y, 
            (0 if in_channel_first else 1), (0 if out_channel_first else 1), 0, (0 if not one_by_one else 1), scans, 
            BC, BH, BW, C, H, W, NH, NW
        )
        return y
        
    @staticmethod
    def backward(ctx, y: torch.Tensor):
        in_channel_first = ctx.in_channel_first
        out_channel_first = ctx.out_channel_first
        one_by_one = ctx.one_by_one
        scans = ctx.scans
        B, C, H, W = ctx.shape
        BC, BH, BW, NC, NH, NW = ctx.triton_shape
        if one_by_one:
            x = y.new_empty((B, 4, C, H, W)) if in_channel_first else y.new_empty((B, H, W, 4, C))
        else:
            x = y.new_empty((B, C, H, W)) if in_channel_first else y.new_empty((B, H, W, C))
        
        triton_cross_scan_flex[(NH * NW, NC, B)](
            x, y.contiguous(), 
            (0 if in_channel_first else 1), (0 if out_channel_first else 1), 1, (0 if not one_by_one else 1), scans,
            BC, BH, BW, C, H, W, NH, NW
        )
        return x, None, None, None, None


class CrossMergeTritonF(torch.autograd.Function):
    @staticmethod
    def forward(ctx, y: torch.Tensor, in_channel_first=True, out_channel_first=True, one_by_one=False, scans=0):
        if out_channel_first:
            B, _, C, H, W = y.shape
        else:
            B, H, W, _, C = y.shape
        B, C, H, W = int(B), int(C), int(H), int(W)
        BC, BH, BW = 1, 32, 32
        NH, NW, NC = triton.cdiv(H, BH), triton.cdiv(W, BW), triton.cdiv(C, BC)
        ctx.in_channel_first = in_channel_first
        ctx.out_channel_first = out_channel_first
        ctx.one_by_one = one_by_one
        ctx.scans = scans
        ctx.shape = (B, C, H, W)
        ctx.triton_shape = (BC, BH, BW, NC, NH, NW)
        if one_by_one:
            x = y.new_empty((B, 4, C, H * W)) if in_channel_first else y.new_empty((B, H * W, 4, C))
        else:
            x = y.new_empty((B, C, H * W)) if in_channel_first else y.new_empty((B, H * W, C))
        triton_cross_scan_flex[(NH * NW, NC, B)](
            x, y.contiguous(), 
            (0 if in_channel_first else 1), (0 if out_channel_first else 1), 1, (0 if not one_by_one else 1), scans,
            BC, BH, BW, C, H, W, NH, NW
        )
        return x
        
    @staticmethod
    def backward(ctx, x: torch.Tensor):
        in_channel_first = ctx.in_channel_first
        out_channel_first = ctx.out_channel_first
        one_by_one = ctx.one_by_one
        scans = ctx.scans
        B, C, H, W = ctx.shape
        BC, BH, BW, NC, NH, NW = ctx.triton_shape
        y = x.new_empty((B, 4, C, H, W)) if out_channel_first else x.new_empty((B, H, W, 4, C))
        triton_cross_scan_flex[(NH * NW, NC, B)](
            x.contiguous(), y, 
            (0 if in_channel_first else 1), (0 if out_channel_first else 1), 0, (0 if not one_by_one else 1), scans,
            BC, BH, BW, C, H, W, NH, NW
        )
        return y, None, None, None, None, None


# @torch.compile(options={"triton.cudagraphs": True}, fullgraph=True)
def cross_scan_fn(x: torch.Tensor, in_channel_first=True, out_channel_first=True, one_by_one=False, scans=0, force_torch=False):
    # x: (B, C, H, W) | (B, H, W, C) | (B, 4, C, H, W) | (B, H, W, 4, C)
    # y: (B, 4, C, L) | (B, L, 4, C)
    # scans: 0: cross scan; 1 unidirectional; 2: bidirectional;
    CSF = CrossScanTritonF if WITH_TRITON and x.is_cuda and (not force_torch) else CrossScanF
    if x.is_cuda:
        with torch.cuda.device(x.device):
            return CSF.apply(x, in_channel_first, out_channel_first, one_by_one, scans)
    else:
        return CrossScanF.apply(x, in_channel_first, out_channel_first, one_by_one, scans)


# @torch.compile(options={"triton.cudagraphs": True}, fullgraph=True)
def cross_merge_fn(y: torch.Tensor, in_channel_first=True, out_channel_first=True, one_by_one=False, scans=0, force_torch=False):
    # y: (B, 4, C, L) | (B, L, 4, C)
    # x: (B, C, H * W) | (B, H * W, C) | (B, 4, C, H * W) | (B, H * W, 4, C)
    # scans: 0: cross scan; 1 unidirectional; 2: bidirectional;
    CMF = CrossMergeTritonF if WITH_TRITON and y.is_cuda and (not force_torch) else CrossMergeF
    if y.is_cuda:
        with torch.cuda.device(y.device):
            return CMF.apply(y, in_channel_first, out_channel_first, one_by_one, scans)
    else:
        return CrossMergeF.apply(y, in_channel_first, out_channel_first, one_by_one, scans)


##########################################################
# csms6s.py
##########################################################

WITH_SELECTIVESCAN_MAMBA = True
try:
    import selective_scan_cuda
except ImportError:
    WITH_SELECTIVESCAN_MAMBA = False


def selective_scan_torch(
    u: torch.Tensor, # (B, K * C, L)
    delta: torch.Tensor, # (B, K * C, L)
    A: torch.Tensor, # (K * C, N)
    B: torch.Tensor, # (B, K, N, L)
    C: torch.Tensor, # (B, K, N, L)
    D: torch.Tensor = None, # (K * C)
    delta_bias: torch.Tensor = None, # (K * C)
    delta_softplus=True, 
    oflex=True, 
    *args,
    **kwargs
):
    dtype_in = u.dtype
    Batch, K, N, L = B.shape
    KCdim = u.shape[1]
    Cdim = int(KCdim / K)
    assert u.shape == (Batch, KCdim, L)
    assert delta.shape == (Batch, KCdim, L)
    assert A.shape == (KCdim, N)
    assert C.shape == B.shape

    if delta_bias is not None:
        delta = delta + delta_bias[..., None]
    if delta_softplus:
        delta = torch.nn.functional.softplus(delta)
            
    u, delta, A, B, C = u.float(), delta.float(), A.float(), B.float(), C.float()
    B = B.view(Batch, K, 1, N, L).repeat(1, 1, Cdim, 1, 1).view(Batch, KCdim, N, L)
    C = C.view(Batch, K, 1, N, L).repeat(1, 1, Cdim, 1, 1).view(Batch, KCdim, N, L)
    deltaA = torch.exp(torch.einsum('bdl,dn->bdln', delta, A))
    deltaB_u = torch.einsum('bdl,bdnl,bdl->bdln', delta, B, u)
    
    if True:
        x = A.new_zeros((Batch, KCdim, N))
        ys = []
        for i in range(L):
            x = deltaA[:, :, i, :] * x + deltaB_u[:, :, i, :]
            y = torch.einsum('bdn,bdn->bd', x, C[:, :, :, i])
            ys.append(y)
        y = torch.stack(ys, dim=2) # (B, C, L)
    
    out = y if D is None else y + u * D.unsqueeze(-1)
    return out if oflex else out.to(dtype=dtype_in)


class SelectiveScanCuda(torch.autograd.Function):
    @staticmethod
    @torch.cuda.amp.custom_fwd
    def forward(ctx, u, delta, A, B, C, D=None, delta_bias=None, delta_softplus=False, oflex=True, backend=None):
        ctx.delta_softplus = delta_softplus
        # backend = "oflex" if WITH_SELECTIVESCAN_OFLEX and (backend is None) else backend
        # backend = "core" if WITH_SELECTIVESCAN_CORE and (backend is None) else backend
        backend = "mamba" if WITH_SELECTIVESCAN_MAMBA and (backend is None) else backend
        ctx.backend = backend
        if backend == "oflex":
            out, x, *rest = selective_scan_cuda_oflex.fwd(u, delta, A, B, C, D, delta_bias, delta_softplus, 1, oflex)
        elif backend == "mamba":
            out, x, *rest = selective_scan_cuda.fwd(u, delta, A, B, C, D, None, delta_bias, delta_softplus)
        ctx.save_for_backward(u, delta, A, B, C, D, delta_bias, x)
        return out
    
    @staticmethod
    @torch.cuda.amp.custom_bwd
    def backward(ctx, dout, *args):
        u, delta, A, B, C, D, delta_bias, x = ctx.saved_tensors
        backend = ctx.backend
        if dout.stride(-1) != 1:
            dout = dout.contiguous()
        if backend == "oflex":
            du, ddelta, dA, dB, dC, dD, ddelta_bias, *rest = selective_scan_cuda_oflex.bwd(
                u, delta, A, B, C, D, delta_bias, dout, x, ctx.delta_softplus, 1
            )
        elif backend == "mamba":
            du, ddelta, dA, dB, dC, dD, ddelta_bias, *rest = selective_scan_cuda.bwd(
                u, delta, A, B, C, D, None, delta_bias, dout, x, None, None, ctx.delta_softplus,
                False
            )
        return du, ddelta, dA, dB, dC, dD, ddelta_bias, None, None, None


def selective_scan_fn(
    u: torch.Tensor, # (B, K * C, L)
    delta: torch.Tensor, # (B, K * C, L)
    A: torch.Tensor, # (K * C, N)
    B: torch.Tensor, # (B, K, N, L)
    C: torch.Tensor, # (B, K, N, L)
    D: torch.Tensor = None, # (K * C)
    delta_bias: torch.Tensor = None, # (K * C)
    delta_softplus=True, 
    oflex=True,
    backend=None,
):
    fn = selective_scan_torch if backend == "torch" or (not WITH_SELECTIVESCAN_MAMBA) else SelectiveScanCuda.apply
    return fn(u, delta, A, B, C, D, delta_bias, delta_softplus, oflex, backend)

##########################################################
############## HuggingFace modeling file #################
##########################################################

class VMambaLinear2d(nn.Linear):
    def __init__(self, *args, groups=1, **kwargs):
        nn.Linear.__init__(self, *args, **kwargs)
        self.groups = groups
    
    def forward(self, x: torch.Tensor):
        if len(x.shape) == 4:
            return F.conv2d(x, self.weight[:, :, None, None], self.bias, groups=self.groups)
        elif len(x.shape) == 3:
            return F.conv1d(x, self.weight[:, :, None], self.bias, groups=self.groups)

    def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs):
        self_state_dict = self.state_dict()
        load_state_dict_keys = list(state_dict.keys())
        if prefix + "weight" in load_state_dict_keys:
            state_dict[prefix + "weight"] = state_dict[prefix + "weight"].view_as(self_state_dict["weight"])
        return super()._load_from_state_dict(state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs)


class VMambaLayerNorm2d(nn.LayerNorm):
    def __init__(self, *args, **kwargs):
        nn.LayerNorm.__init__(self, *args, **kwargs)

    def forward(self, x: torch.Tensor):
        x = x.permute(0, 2, 3, 1)
        x = nn.LayerNorm.forward(self, x)
        x = x.permute(0, 3, 1, 2)
        return x


class VMambaPatchEmbeddings(nn.Module):
    """
    This class turns `input_values` into the initial `hidden_states` (patch embeddings) of shape `(batch_size,
    seq_length, hidden_size)` to be consumed by a State-space model.
    """

    def __init__(self, num_channels=3,patch_size=4,embed_dim=96):
        super().__init__()

        stride = patch_size // 2
        kernel_size = stride + 1
        padding = 1

        self.projection = nn.Sequential(
            nn.Conv2d(num_channels, embed_dim // 2, kernel_size=kernel_size, stride=stride, padding=padding),
            VMambaLayerNorm2d(embed_dim // 2),
            nn.GELU(),
            nn.Conv2d(embed_dim // 2, embed_dim, kernel_size=kernel_size, stride=stride, padding=padding),
            VMambaLayerNorm2d(embed_dim),
        )

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        x = self.projection(x)
        return x


class VMambaDowsample(nn.Module):
    """
    This class downsamples the input tensor using a convolutional layer followed by a layer normalization.
    """
    def __init__(self, dim, out_dim, use_norm=True):
        super().__init__()
        self.down = nn.Conv2d(dim, out_dim, kernel_size=3, stride=2, padding=1)
        self.norm = VMambaLayerNorm2d(out_dim) if use_norm else nn.Identity()

    def forward(self, x):
        x = self.down(x)
        x = self.norm(x)
        return x


class VMambaMlp(nn.Module):
    def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.GELU, drop=0.):
        super().__init__()
        out_features = out_features or in_features
        hidden_features = hidden_features or in_features
        self.fc1 = VMambaLinear2d(in_features, hidden_features)
        self.act = act_layer()
        self.fc2 = VMambaLinear2d(hidden_features, out_features)
        self.drop = nn.Dropout(drop)

    def forward(self, x):
        x = self.fc1(x)
        x = self.act(x)
        x = self.drop(x)
        x = self.fc2(x)
        x = self.drop(x)
        return x


class SS2D(nn.Module):
    def __init__(
        self,
        # basic dims ===========
        d_model=96,
        d_state=16,
        ssm_ratio=2.0,
        dt_rank="auto",
        act_layer=nn.SiLU,
        # dwconv ===============
        d_conv=3,
        conv_bias=True,
        # ======================
        dropout=0.0,
        bias=False,
        # dt init ==============
        dt_min=0.001,
        dt_max=0.1,
        dt_init="random",
        dt_scale=1.0,
        dt_init_floor=1e-4,
        # forward_type="v05_noz" is always used
        # ======================
        **kwargs,
    ):
        super().__init__()
        self.k_group = 4
        self.d_model = int(d_model)
        self.d_state = int(d_state)
        self.d_inner = int(ssm_ratio * d_model)
        self.dt_rank = int(math.ceil(self.d_model / 16) if dt_rank == "auto" else dt_rank)
        self.forward_core = partial(self.forward_corev2, force_fp32=False, no_einsum=True)
        self.with_dconv = d_conv > 1

        # In projection
        self.in_proj = VMambaLinear2d(self.d_model, self.d_inner, bias=bias)
        self.act: nn.Module = act_layer()

        # Convolution
        if self.with_dconv:
            self.conv2d = nn.Conv2d(
                in_channels=self.d_inner,
                out_channels=self.d_inner,
                groups=self.d_inner,
                bias=conv_bias,
                kernel_size=d_conv,
                padding=(d_conv - 1) // 2,
            )

        # x_proj and dt_proj
        self.x_proj = VMambaLinear2d(self.d_inner, self.k_group * (self.dt_rank + self.d_state * 2), groups=self.k_group, bias=False)
        self.dt_projs = VMambaLinear2d(self.dt_rank, self.k_group * self.d_inner, groups=self.k_group, bias=False)

        # out projection
        self.out_proj = VMambaLinear2d(self.d_inner, self.d_model, bias=bias)
        self.dropout = nn.Dropout(dropout) if dropout > 0. else nn.Identity()

        # Initialization
        self.A_logs, self.Ds, self.dt_projs_weight, self.dt_projs_bias = self.init_dt_A_D(
            self.d_state, self.dt_rank, self.d_inner, dt_scale, dt_init, dt_min, dt_max, dt_init_floor, k_group=self.k_group,
        )
        self.dt_projs.weight.data = self.dt_projs_weight.data.view(self.dt_projs.weight.shape)
        # self.dt_projs.bias.data = self.dt_projs_bias.data.view(self.dt_projs.bias.shape)
        del self.dt_projs_weight
        # del self.dt_projs_bias
        # Define out_norm directly with "LN2D"
        self.out_norm = VMambaLayerNorm2d(self.d_inner)

    @staticmethod
    def dt_init(dt_rank, d_inner, dt_scale=1.0, dt_init="random", dt_min=0.001, dt_max=0.1, dt_init_floor=1e-4):
        dt_proj = nn.Linear(dt_rank, d_inner, bias=True)

        dt_init_std = dt_rank**-0.5 * dt_scale
        if dt_init == "constant":
            nn.init.constant_(dt_proj.weight, dt_init_std)
        elif dt_init == "random":
            nn.init.uniform_(dt_proj.weight, -dt_init_std, dt_init_std)
        else:
            raise NotImplementedError

        dt = torch.exp(
            torch.rand(d_inner) * (math.log(dt_max) - math.log(dt_min))
            + math.log(dt_min)
        ).clamp(min=dt_init_floor)

        inv_dt = dt + torch.log(-torch.expm1(-dt))
        with torch.no_grad():
            dt_proj.bias.copy_(inv_dt)
        
        return dt_proj

    @staticmethod
    def A_log_init(d_state, d_inner, copies=-1, device=None, merge=True):
        A = torch.arange(1, d_state + 1, dtype=torch.float32, device=device).view(1, -1).repeat(d_inner, 1).contiguous()
        A_log = torch.log(A)
        if copies > 0:
            A_log = A_log[None].repeat(copies, 1, 1).contiguous()
            if merge:
                A_log = A_log.flatten(0, 1)
        A_log = nn.Parameter(A_log)
        A_log._no_weight_decay = True
        return A_log

    @staticmethod
    def D_init(d_inner, copies=-1, device=None, merge=True):
        D = torch.ones(d_inner, device=device)
        if copies > 0:
            D = D[None].repeat(copies, 1).contiguous()
            if merge:
                D = D.flatten(0, 1)
        D = nn.Parameter(D)
        D._no_weight_decay = True
        return D

    @classmethod
    def init_dt_A_D(cls, d_state, dt_rank, d_inner, dt_scale, dt_init, dt_min, dt_max, dt_init_floor, k_group=4):
        dt_projs = [
            cls.dt_init(dt_rank, d_inner, dt_scale, dt_init, dt_min, dt_max, dt_init_floor)
            for _ in range(k_group)
        ]
        dt_projs_weight = nn.Parameter(torch.stack([t.weight for t in dt_projs], dim=0))
        dt_projs_bias = nn.Parameter(torch.stack([t.bias for t in dt_projs], dim=0))
        del dt_projs
            
        A_logs = cls.A_log_init(d_state, d_inner, copies=k_group, merge=True)
        Ds = cls.D_init(d_inner, copies=k_group, merge=True)
        return A_logs, Ds, dt_projs_weight, dt_projs_bias

    def forward_corev2(
        self,
        x: torch.Tensor,
        force_fp32=False,
        no_einsum=True,
    ):
        B, D, H, W = x.shape
        N = self.d_state
        L = H * W

        xs = cross_scan_fn(x, in_channel_first=True, out_channel_first=True)
        x_dbl = self.x_proj(xs.view(B, -1, L))
        dts, Bs, Cs = torch.split(x_dbl.view(B, self.k_group, -1, L), [self.dt_rank, N, N], dim=2)
        dts = dts.contiguous().view(B, -1, L)
        dts = self.dt_projs(dts)

        xs = xs.view(B, -1, L)
        dts = dts.contiguous().view(B, -1, L)
        As = -self.A_logs.to(torch.float32).exp()
        Ds = self.Ds.to(torch.float32)
        Bs = Bs.contiguous().view(B, self.k_group, N, L)
        Cs = Cs.contiguous().view(B, self.k_group, N, L)
        delta_bias = self.dt_projs_bias.view(-1).to(torch.float32)
        
        ys = selective_scan_fn(
            xs, dts, As, Bs, Cs, Ds, delta_bias, delta_softplus=True, backend="mamba"
        ).view(B, self.k_group, -1, H, W)
        
        y = cross_merge_fn(ys, in_channel_first=True, out_channel_first=True)
        y = y.view(B, -1, H, W)
        y = self.out_norm(y)
        return y.to(x.dtype)

    def forward(self, x: torch.Tensor):
        x = self.in_proj(x)
        x = self.conv2d(x)
            
        x = self.act(x)
        y = self.forward_core(x)
        
        out = self.dropout(self.out_proj(y))
        return out


class VSSBlock(nn.Module):
    def __init__(
        self,
        hidden_dim: int = 0,
        drop_path: float = 0,
        ssm_d_state: int = 1,
        ssm_ratio=1.0,
        ssm_dt_rank: Any = "auto",
        ssm_act_layer=nn.SiLU,
        ssm_conv: int = 3,
        ssm_conv_bias=False,
        ssm_drop_rate: float = 0,
        mlp_ratio=4.0,
        mlp_act_layer=nn.GELU,
        mlp_drop_rate: float = 0.0,
        use_checkpoint: bool = False,
        post_norm: bool = False,
        **kwargs,
    ):
        super().__init__()
        self.ssm_branch = ssm_ratio > 0
        self.mlp_branch = mlp_ratio > 0
        self.use_checkpoint = use_checkpoint
        self.post_norm = post_norm

        if self.ssm_branch:
            self.norm = VMambaLayerNorm2d(hidden_dim)
            self.op = SS2D(
                d_model=hidden_dim, 
                d_state=ssm_d_state, 
                ssm_ratio=ssm_ratio,
                dt_rank=ssm_dt_rank,
                act_layer=ssm_act_layer,
                d_conv=ssm_conv,
                conv_bias=ssm_conv_bias,
                dropout=ssm_drop_rate,
            )
        
        self.drop_path = DropPath(drop_path)
        
        if self.mlp_branch:
            self.norm2 = VMambaLayerNorm2d(hidden_dim)
            mlp_hidden_dim = int(hidden_dim * mlp_ratio)
            self.mlp = VMambaMlp(in_features=hidden_dim, hidden_features=mlp_hidden_dim, act_layer=mlp_act_layer, drop=mlp_drop_rate)

    def _forward(self, input: torch.Tensor):
        x = input
        if self.ssm_branch:
            if self.post_norm:
                x = x + self.drop_path(self.norm(self.op(x)))
            else:
                x = x + self.drop_path(self.op(self.norm(x)))
        if self.mlp_branch:
            if self.post_norm:
                x = x + self.drop_path(self.norm2(self.mlp(x))) 
            else:
                x = x + self.drop_path(self.mlp(self.norm2(x)))
        return x

    def forward(self, input: torch.Tensor):
        if self.use_checkpoint:
            return checkpoint.checkpoint(self._forward, input)
        else:
            return self._forward(input)

class VMambaLayer(nn.Module):

    def __init__(
        self,
        input_dim,
        depth,
        drop_path=0.0,
        norm_layer=VMambaLayerNorm2d,
        downsample=nn.Identity(),
        use_checkpoint=False,
        **kwargs,
    ):
        super().__init__()
        self.input_dim = input_dim
        self.use_checkpoint = use_checkpoint

        self.blocks = nn.ModuleList()
        for i in range(depth):
            self.blocks.append(
                VSSBlock(hidden_dim=input_dim,
                    drop_path=drop_path[i] if isinstance(drop_path, list) else drop_path,
                    norm_layer=norm_layer,use_checkpoint=use_checkpoint,**kwargs,
                )
            )
        
        self.downsample = downsample

    def forward(self, x):
        for block in self.blocks:
            x = block(x)

        x = self.downsample(x)
        return x

class VMambaPreTrainedModel(PreTrainedModel):
    """
    An abstract class to handle weights initialization and
    a simple interface for downloading and loading pretrained models.
    """

    config_class = VMambaConfig
    base_model_prefix = "vmamba"
    supports_gradient_checkpointing = False

    def _init_weights(self, module: Union[nn.Linear, nn.Conv2d, nn.LayerNorm]) -> None:
        """Initialize the weights"""
        if isinstance(module, nn.Linear):
            trunc_normal_(module.weight, std=0.02)
            if isinstance(module, nn.Linear) and module.bias is not None:
                nn.init.constant_(module.bias, 0)
        elif isinstance(module, nn.LayerNorm):
            nn.init.constant_(module.bias, 0)
            nn.init.constant_(module.weight, 1.0)


class VMambaModel(VMambaPreTrainedModel):
    def __init__(self, config):
        super().__init__(config)
        self.config = config

        dims = config.dims
        if isinstance(dims, int):
            dims = [int(dims * 2**i_layer) for i_layer in range(self.num_layers)]

        self.dims = dims
        self.patch_embeddings = VMambaPatchEmbeddings(patch_size=config.patch_size,
                                                     embed_dim=dims[0])
        
        self.num_layers = len(config.depths)
        dpr = [x.item() for x in torch.linspace(0, config.drop_path_rate, sum(config.depths))]
        self.num_features = dims[-1]

        self.layers = nn.ModuleList()
        for i in range(self.num_layers):
            layer = VMambaLayer(
                input_dim=self.dims[i],
                depth=config.depths[i],
                drop_path=dpr[sum(config.depths[:i]):sum(config.depths[:i+1])],
                downsample=VMambaDowsample(self.dims[i], self.dims[i+1]) if i < self.num_layers - 1 else nn.Identity(),
                use_checkpoint=config.use_checkpoint,
            )
            self.layers.append(layer)
        
        self.norm = VMambaLayerNorm2d(self.num_features)
        self.avgpool = nn.AdaptiveAvgPool2d(1)

    def get_input_embeddings(self) -> VMambaPatchEmbeddings:
        return self.patch_embeddings
    
    def forward(self, input_values: torch.Tensor):
        x = self.patch_embeddings(input_values)
        for layer in self.layers:
            x = layer(x)
        x = self.norm(x)
        x = self.avgpool(x).flatten(1)
        return x


class VMambaForImageClassification(VMambaPreTrainedModel):
    def __init__(self, config):
        super().__init__(config)

        self.num_classes = config.num_classes
        self.vmamba = VMambaModel(config)
        self.head = nn.Linear(self.vmamba.num_features, self.num_classes) if self.num_classes > 0 else nn.Identity()

        # Initialize weights and apply final processing
        self.post_init()

    def forward(
        self,
        pixel_values: Optional[torch.Tensor] = None,
        labels: Optional[torch.Tensor] = None,
        return_dict: Optional[bool] = None,
    ):

        outputs = self.vmamba(
            pixel_values,
        )

        logits = self.head(outputs)

        loss = None
        if labels is not None:
            labels = labels.to(logits.device)
            if self.config.loss_type == "ce":
                loss_fct = CrossEntropyLoss()
                loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
            elif self.config.problem_type == "bce":
                loss_fct = BCEWithLogitsLoss()
                loss = loss_fct(logits, labels)

        if return_dict:
            output = (logits,) + (outputs,)
            return ((loss,) + output) if loss is not None else output

        return ImageClassifierOutput(
            loss=loss,
            logits=logits,
            hidden_states=outputs,
        )

__all__ = [
    "VMambaModel",
    "VMambaPreTrainedModel",
    "VMambaForImageClassification",
]