#Original code can be found on: https://github.com/black-forest-labs/flux

from dataclasses import dataclass

import torch
from torch import Tensor, nn
from einops import rearrange, repeat
import comfy.ldm.common_dit
import comfy.patcher_extension

from .layers import (
    DoubleStreamBlock,
    EmbedND,
    LastLayer,
    MLPEmbedder,
    SingleStreamBlock,
    timestep_embedding,
)

@dataclass
class FluxParams:
    in_channels: int
    out_channels: int
    vec_in_dim: int
    context_in_dim: int
    hidden_size: int
    mlp_ratio: float
    num_heads: int
    depth: int
    depth_single_blocks: int
    axes_dim: list
    theta: int
    patch_size: int
    qkv_bias: bool
    guidance_embed: bool


class Flux(nn.Module):
    """
    Transformer model for flow matching on sequences.
    """

    def __init__(self, image_model=None, final_layer=True, dtype=None, device=None, operations=None, **kwargs):
        super().__init__()
        self.dtype = dtype
        params = FluxParams(**kwargs)
        self.params = params
        self.patch_size = params.patch_size
        self.in_channels = params.in_channels * params.patch_size * params.patch_size
        self.out_channels = params.out_channels * params.patch_size * params.patch_size
        if params.hidden_size % params.num_heads != 0:
            raise ValueError(
                f"Hidden size {params.hidden_size} must be divisible by num_heads {params.num_heads}"
            )
        pe_dim = params.hidden_size // params.num_heads
        if sum(params.axes_dim) != pe_dim:
            raise ValueError(f"Got {params.axes_dim} but expected positional dim {pe_dim}")
        self.hidden_size = params.hidden_size
        self.num_heads = params.num_heads
        self.pe_embedder = EmbedND(dim=pe_dim, theta=params.theta, axes_dim=params.axes_dim)
        self.img_in = operations.Linear(self.in_channels, self.hidden_size, bias=True, dtype=dtype, device=device)
        self.time_in = MLPEmbedder(in_dim=256, hidden_dim=self.hidden_size, dtype=dtype, device=device, operations=operations)
        self.vector_in = MLPEmbedder(params.vec_in_dim, self.hidden_size, dtype=dtype, device=device, operations=operations)
        self.guidance_in = (
            MLPEmbedder(in_dim=256, hidden_dim=self.hidden_size, dtype=dtype, device=device, operations=operations) if params.guidance_embed else nn.Identity()
        )
        self.txt_in = operations.Linear(params.context_in_dim, self.hidden_size, dtype=dtype, device=device)

        self.double_blocks = nn.ModuleList(
            [
                DoubleStreamBlock(
                    self.hidden_size,
                    self.num_heads,
                    mlp_ratio=params.mlp_ratio,
                    qkv_bias=params.qkv_bias,
                    dtype=dtype, device=device, operations=operations
                )
                for _ in range(params.depth)
            ]
        )

        self.single_blocks = nn.ModuleList(
            [
                SingleStreamBlock(self.hidden_size, self.num_heads, mlp_ratio=params.mlp_ratio, dtype=dtype, device=device, operations=operations)
                for _ in range(params.depth_single_blocks)
            ]
        )

        if final_layer:
            self.final_layer = LastLayer(self.hidden_size, 1, self.out_channels, dtype=dtype, device=device, operations=operations)

    def forward_orig(
        self,
        img: Tensor,
        img_ids: Tensor,
        txt: Tensor,
        txt_ids: Tensor,
        timesteps: Tensor,
        y: Tensor,
        guidance: Tensor = None,
        control = None,
        transformer_options={},
        attn_mask: Tensor = None,
    ) -> Tensor:

        if y is None:
            y = torch.zeros((img.shape[0], self.params.vec_in_dim), device=img.device, dtype=img.dtype)

        patches_replace = transformer_options.get("patches_replace", {})
        if img.ndim != 3 or txt.ndim != 3:
            raise ValueError("Input img and txt tensors must have 3 dimensions.")

        # running on sequences img
        img = self.img_in(img)
        vec = self.time_in(timestep_embedding(timesteps, 256).to(img.dtype))
        if self.params.guidance_embed:
            if guidance is not None:
                vec = vec + self.guidance_in(timestep_embedding(guidance, 256).to(img.dtype))

        vec = vec + self.vector_in(y[:,:self.params.vec_in_dim])
        txt = self.txt_in(txt)

        if img_ids is not None:
            ids = torch.cat((txt_ids, img_ids), dim=1)
            pe = self.pe_embedder(ids)
        else:
            pe = None

        blocks_replace = patches_replace.get("dit", {})
        for i, block in enumerate(self.double_blocks):
            if ("double_block", i) in blocks_replace:
                def block_wrap(args):
                    out = {}
                    out["img"], out["txt"] = block(img=args["img"],
                                                   txt=args["txt"],
                                                   vec=args["vec"],
                                                   pe=args["pe"],
                                                   attn_mask=args.get("attn_mask"))
                    return out

                out = blocks_replace[("double_block", i)]({"img": img,
                                                           "txt": txt,
                                                           "vec": vec,
                                                           "pe": pe,
                                                           "attn_mask": attn_mask},
                                                          {"original_block": block_wrap})
                txt = out["txt"]
                img = out["img"]
            else:
                img, txt = block(img=img,
                                 txt=txt,
                                 vec=vec,
                                 pe=pe,
                                 attn_mask=attn_mask)

            if control is not None: # Controlnet
                control_i = control.get("input")
                if i < len(control_i):
                    add = control_i[i]
                    if add is not None:
                        img[:, :add.shape[1]] += add

        if img.dtype == torch.float16:
            img = torch.nan_to_num(img, nan=0.0, posinf=65504, neginf=-65504)

        img = torch.cat((txt, img), 1)

        for i, block in enumerate(self.single_blocks):
            if ("single_block", i) in blocks_replace:
                def block_wrap(args):
                    out = {}
                    out["img"] = block(args["img"],
                                       vec=args["vec"],
                                       pe=args["pe"],
                                       attn_mask=args.get("attn_mask"))
                    return out

                out = blocks_replace[("single_block", i)]({"img": img,
                                                           "vec": vec,
                                                           "pe": pe,
                                                           "attn_mask": attn_mask},
                                                          {"original_block": block_wrap})
                img = out["img"]
            else:
                img = block(img, vec=vec, pe=pe, attn_mask=attn_mask)

            if control is not None: # Controlnet
                control_o = control.get("output")
                if i < len(control_o):
                    add = control_o[i]
                    if add is not None:
                        img[:, txt.shape[1] : txt.shape[1] + add.shape[1], ...] += add

        img = img[:, txt.shape[1] :, ...]

        img = self.final_layer(img, vec)  # (N, T, patch_size ** 2 * out_channels)
        return img

    def process_img(self, x, index=0, h_offset=0, w_offset=0):
        bs, c, h, w = x.shape
        patch_size = self.patch_size
        x = comfy.ldm.common_dit.pad_to_patch_size(x, (patch_size, patch_size))

        img = rearrange(x, "b c (h ph) (w pw) -> b (h w) (c ph pw)", ph=patch_size, pw=patch_size)
        h_len = ((h + (patch_size // 2)) // patch_size)
        w_len = ((w + (patch_size // 2)) // patch_size)

        h_offset = ((h_offset + (patch_size // 2)) // patch_size)
        w_offset = ((w_offset + (patch_size // 2)) // patch_size)

        img_ids = torch.zeros((h_len, w_len, 3), device=x.device, dtype=x.dtype)
        img_ids[:, :, 0] = img_ids[:, :, 1] + index
        img_ids[:, :, 1] = img_ids[:, :, 1] + torch.linspace(h_offset, h_len - 1 + h_offset, steps=h_len, device=x.device, dtype=x.dtype).unsqueeze(1)
        img_ids[:, :, 2] = img_ids[:, :, 2] + torch.linspace(w_offset, w_len - 1 + w_offset, steps=w_len, device=x.device, dtype=x.dtype).unsqueeze(0)
        return img, repeat(img_ids, "h w c -> b (h w) c", b=bs)

    def forward(self, x, timestep, context, y=None, guidance=None, ref_latents=None, control=None, transformer_options={}, **kwargs):
        return comfy.patcher_extension.WrapperExecutor.new_class_executor(
            self._forward,
            self,
            comfy.patcher_extension.get_all_wrappers(comfy.patcher_extension.WrappersMP.DIFFUSION_MODEL, transformer_options)
        ).execute(x, timestep, context, y, guidance, ref_latents, control, transformer_options, **kwargs)

    def _forward(self, x, timestep, context, y=None, guidance=None, ref_latents=None, control=None, transformer_options={}, **kwargs):
        bs, c, h_orig, w_orig = x.shape
        patch_size = self.patch_size

        h_len = ((h_orig + (patch_size // 2)) // patch_size)
        w_len = ((w_orig + (patch_size // 2)) // patch_size)
        img, img_ids = self.process_img(x)
        img_tokens = img.shape[1]
        if ref_latents is not None:
            h = 0
            w = 0
            index = 0
            index_ref_method = kwargs.get("ref_latents_method", "offset") == "index"
            for ref in ref_latents:
                if index_ref_method:
                    index += 1
                    h_offset = 0
                    w_offset = 0
                else:
                    index = 1
                    h_offset = 0
                    w_offset = 0
                    if ref.shape[-2] + h > ref.shape[-1] + w:
                        w_offset = w
                    else:
                        h_offset = h
                    h = max(h, ref.shape[-2] + h_offset)
                    w = max(w, ref.shape[-1] + w_offset)

                kontext, kontext_ids = self.process_img(ref, index=index, h_offset=h_offset, w_offset=w_offset)
                img = torch.cat([img, kontext], dim=1)
                img_ids = torch.cat([img_ids, kontext_ids], dim=1)

        txt_ids = torch.zeros((bs, context.shape[1], 3), device=x.device, dtype=x.dtype)
        out = self.forward_orig(img, img_ids, context, txt_ids, timestep, y, guidance, control, transformer_options, attn_mask=kwargs.get("attention_mask", None))
        out = out[:, :img_tokens]
        return rearrange(out, "b (h w) (c ph pw) -> b c (h ph) (w pw)", h=h_len, w=w_len, ph=2, pw=2)[:,:,:h_orig,:w_orig]
