# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
# ruff: noqa: F401

"""
.. _opt_llm:

Optimize Large Language Model
=============================
As large language models (LLMs) have become a popular research topic in many different fields,
deploying them on cloud and edge devices has become a challenging task. In this tutorial, we will
demonstrate how to optimize a large language model using Apache TVM. We will use a pre-trained
TinyLlama model from Hugging Face and deploy it on various devices.
"""

######################################################################
# Review Overall Flow
# -------------------
# .. figure:: https://raw.githubusercontent.com/tlc-pack/web-data/main/images/design/tvm_overall_flow.svg
#    :align: center
#    :width: 80%
#
# The overall flow consists of the following steps:
#
# - **Construct or Import a Model**: Construct a neural network model or import a pre-trained
#   model from other frameworks (e.g. PyTorch, ONNX), and create the TVM IRModule, which contains
#   all the information needed for compilation, including high-level Relax functions for
#   computational graph, and low-level TensorIR functions for tensor program.
# - **Perform Composable Optimizations**: Perform a series of optimization transformations,
#   such as graph optimizations, tensor program optimizations, and library dispatching.
# - **Build and Universal Deployment**: Build the optimized model to a deployable module to the
#   universal runtime, and execute it on different devices, such as CPU, GPU, or other accelerators.
#


######################################################################
# Construct the model architecture
# --------------------------------
# We will use a pre-trained TinyLlama model from Hugging Face. However, usually we only load the
# pre-trained weight from Hugging Face but not the model architecture. We need to construct the
# model architecture by ourselves. Apache TVM prepares a PyTorch-liked API to construct the model
# architecture. We can use the API to construct the model architecture.

import dataclasses
import enum
import os
from pathlib import Path
from pprint import pprint

from tvm_ffi import Shape

import tvm
from tvm import relax, te, tirx
from tvm.relax import register_pipeline
from tvm.relax.frontend import nn
from tvm.relax.frontend.nn import Tensor, op
from tvm.relax.frontend.nn.llm.kv_cache import PagedKVCache, TIRPagedKVCache
from tvm.s_tir import dlight

######################################################################
# First, we need to define the model configuration. The configuration includes the key parameters
# of the model, such as hidden size, intermediate size, etc. Here for convenience, we define a
# constant config specially for the TinyLlama model.


@dataclasses.dataclass
class LlamaConfig:
    hidden_size: int = 2048
    intermediate_size: int = 5632
    num_attention_heads: int = 32
    num_hidden_layers: int = 22
    rms_norm_eps: float = 1e-05
    vocab_size: int = 32000
    rope_theta: int = 10000
    context_window_size: int = 2048
    prefill_chunk_size: int = 2048
    num_key_value_heads: int = 4
    head_dim: int = 64  # hidden_size // num_attention_heads


dev = tvm.cuda(0)
target = tvm.target.Target.from_device(dev)


######################################################################
# Next, we define the RoPE mode of the Paged KV cache. The RoPE mode is used to apply the
# Relative Positional Encoding (RoPE) to the query and key tensors. The RoPE mode can be set to
# `NONE`, `NORMAL`, or `INLINE`. If the RoPE mode is `NONE`, the KV cache will not apply RoPE to
# the query and key tensors. If the RoPE mode is `NORMAL`, RoPE will be applied to the key tensor
# before adding the key tensor to the cache. If the RoPE mode is `INLINE`, RoPE will be applied to
# the query and key tensors in the attention kernel on-the-fly.


class RopeMode(enum.IntEnum):
    """The RoPE mode of the Paged KV cache.
    If it is none, the KV cache will not apply RoPE to q and k.
    If it is normal, RoPE will be applied to k before adding k to cache.
    Otherwise, RoPE will be applied to q/k in attention kernel on-the-fly.
    """

    NONE = 0
    NORMAL = 1
    INLINE = 2


######################################################################
# Secondly, we define the model architecture. The model architecture consists of three parts:
#
# - Embedding layer: The embedding layer converts the input token IDs to the hidden states.
# - Decoder layers: The decoder layers are the core of the model. Each decoder layer consists of
#   a self-attention layer and a feed-forward network (FFN) layer.
# - Output layer: The output layer converts the hidden states to the logits.
#
# First we define the FFN layer. Note that the following FFN layer is optimized implementation
# where we fuse the gate and up projection into one kernel.
# The naive implementation of FFN layer is: ``FFN(x) = down_proj(silu(gate(x)) * up(x))``
# We could combine the ``gate`` and ``up`` projection into one kernel for better performance.
# The optimized implementation is:
#
# .. code-block:: python
#
#   concat_x = gate_up(x)
#   gate_x, up_x = split(concat_x, 2, axis=-1)
#   FFN(x) = down_proj(silu(gate_x) * up_x)
#


class LlamaFFN(nn.Module):
    def __init__(self, config: LlamaConfig):
        super().__init__()
        self.gate_up_proj = nn.Linear(
            in_features=config.hidden_size,
            out_features=2 * config.intermediate_size,
            bias=False,
        )
        self.down_proj = nn.Linear(config.intermediate_size, config.hidden_size, bias=False)

    def forward(self, x: Tensor):
        concat_x1_x2 = self.gate_up_proj(x)
        x1, x2 = op.split(concat_x1_x2, 2, axis=-1)
        return self.down_proj(op.silu(x1) * x2)


######################################################################
# Then we define the self-attention layer. The self-attention layer consists of three parts:
#
# - QKV projection: The QKV projection converts the input hidden states to the query, key, and
#   value tensors.
# - Attention: The attention layer computes the attention scores and applies the softmax
#   operation.
# - Output projection: The output projection converts the attention output to the hidden states.
#
# We perform optimizations on the different parts of the self-attention layer:
#
# - QKV projection: We leverage the horizontal fusion on QKV projection and fuse them into one
#   kernel.
# - Attention: We leverage the horizontal fusion on attention and fuse the QKV projection and


class LlamaAttention(nn.Module):  # pylint: disable=too-many-instance-attributes
    def __init__(self, config: LlamaConfig):
        self.head_dim = config.head_dim
        self.num_q_heads = config.num_attention_heads
        self.num_kv_heads = config.num_key_value_heads
        # horizontal fusion on QKV projection
        self.qkv_proj = nn.Linear(
            in_features=config.hidden_size,
            out_features=(self.num_q_heads + 2 * self.num_kv_heads) * self.head_dim,
            bias=False,
        )
        self.o_proj = nn.Linear(self.num_q_heads * self.head_dim, config.hidden_size, bias=False)

    def forward(self, hidden_states: Tensor, paged_kv_cache: PagedKVCache, layer_id: int):
        d, h_q, h_kv = self.head_dim, self.num_q_heads, self.num_kv_heads
        b, s, _ = hidden_states.shape
        # QKV Projection
        qkv = self.qkv_proj(hidden_states)
        qkv = op.reshape(qkv, (b, s, h_q + h_kv + h_kv, d))
        # Attention
        output = op.reshape(
            paged_kv_cache.attention_with_fused_qkv(
                layer_id, qkv, self.num_q_heads, sm_scale=self.head_dim**-0.5
            ),
            (b, s, h_q * d),
        )
        # Output Projection
        return self.o_proj(output)


######################################################################
# Finally, we define the model architecture with FFN and self-attention layers.


class LlamaDecoderLayer(nn.Module):
    def __init__(self, config: LlamaConfig):
        rms_norm_eps = config.rms_norm_eps
        self.self_attn = LlamaAttention(config)
        self.mlp = LlamaFFN(config)
        self.input_layernorm = nn.RMSNorm(config.hidden_size, -1, rms_norm_eps, bias=False)
        self.post_attention_layernorm = nn.RMSNorm(config.hidden_size, -1, rms_norm_eps, bias=False)

    def forward(self, hidden_states: Tensor, paged_kv_cache: PagedKVCache, layer_id: int):
        hidden_states += self.self_attn(
            self.input_layernorm(hidden_states), paged_kv_cache, layer_id
        )
        hidden_states += self.mlp(self.post_attention_layernorm(hidden_states))
        return hidden_states


class LlamaModel(nn.Module):
    def __init__(self, config: LlamaConfig):
        assert config.hidden_size % config.num_attention_heads == 0
        self.embed_tokens = nn.Embedding(config.vocab_size, config.hidden_size)
        self.layers = nn.ModuleList(
            [LlamaDecoderLayer(config) for _ in range(config.num_hidden_layers)]
        )
        self.norm = nn.RMSNorm(config.hidden_size, -1, config.rms_norm_eps, bias=False)

    def forward(self, input_embed: Tensor, paged_kv_cache: PagedKVCache):
        hidden_states = input_embed
        for layer_id, layer in enumerate(self.layers):
            hidden_states = layer(hidden_states, paged_kv_cache, layer_id)
        hidden_states = self.norm(hidden_states)
        return hidden_states


class LlamaForCausalLM(nn.Module):
    def __init__(self, config: LlamaConfig):
        self.model = LlamaModel(config)
        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
        self.num_hidden_layers = config.num_hidden_layers
        self.num_attention_heads = config.num_attention_heads
        self.num_key_value_heads = config.num_key_value_heads
        self.head_dim = config.head_dim
        self.hidden_size = config.hidden_size
        self.vocab_size = config.vocab_size
        self.rope_theta = config.rope_theta
        self.dtype = "float32"

    def to(self, dtype: str | None = None):
        super().to(dtype=dtype)
        if dtype is not None:
            self.dtype = dtype

    def embed(self, input_ids: Tensor):
        return self.model.embed_tokens(input_ids)

    def get_logits(self, hidden_states: Tensor):
        logits = self.lm_head(hidden_states)
        if logits.dtype != "float32":
            logits = logits.astype("float32")
        return logits

    def prefill(self, input_embed: Tensor, paged_kv_cache: PagedKVCache):
        def _index(x: te.Tensor):  # x[:-1,:]
            b, s, d = x.shape
            return te.compute((b, 1, d), lambda i, _, k: x[i, s - 1, k], name="index")

        hidden_states = self.model(input_embed, paged_kv_cache)
        hidden_states = op.tensor_expr_op(_index, name_hint="index", args=[hidden_states])
        logits = self.get_logits(hidden_states)
        return logits, paged_kv_cache

    def decode(self, input_embed: Tensor, paged_kv_cache: PagedKVCache):
        hidden_states = self.model(input_embed, paged_kv_cache)
        logits = self.get_logits(hidden_states)
        return logits, paged_kv_cache

    def create_tir_paged_kv_cache(
        self,
        max_batch_size: tirx.Var,
        max_total_seq_len: tirx.Var,
        prefill_chunk_size: tirx.Var,
        page_size: tirx.Var,
    ) -> PagedKVCache:
        return TIRPagedKVCache(
            attn_kind="mha",
            max_batch_size=max_batch_size,
            max_total_seq_len=max_total_seq_len,
            prefill_chunk_size=prefill_chunk_size,
            page_size=page_size,
            support_sliding_window=0,
            layer_partition=relax.ShapeExpr([0, self.num_hidden_layers]),
            num_hidden_layers=self.num_hidden_layers,
            num_attention_heads=self.num_attention_heads,
            num_key_value_heads=self.num_key_value_heads,
            qk_head_dim=self.head_dim,
            v_head_dim=self.head_dim,
            mla_original_qk_head_dim=0,
            mla_original_v_head_dim=0,
            rope_mode=RopeMode.NORMAL,
            rope_scale=1,
            rope_theta=self.rope_theta,
            rope_scaling={},
            rope_ext_factors=tirx.IntImm("int64", 0),
            rotary_dim=self.head_dim,
            dtype=self.dtype,
            target=target,
            enable_disaggregation=False,
        )

    def get_default_spec(self):
        mod_spec = {
            "embed": {
                "input_ids": nn.spec.Tensor(["seq_len"], "int32"),
                "$": {
                    "param_mode": "packed",
                    "effect_mode": "none",
                },
            },
            "prefill": {
                "input_embed": nn.spec.Tensor([1, "seq_len", self.hidden_size], self.dtype),
                "paged_kv_cache": nn.spec.Object(object_type=PagedKVCache),
                "$": {
                    "param_mode": "packed",
                    "effect_mode": "none",
                },
            },
            "decode": {
                "input_embed": nn.spec.Tensor([1, 1, self.hidden_size], self.dtype),
                "paged_kv_cache": nn.spec.Object(object_type=PagedKVCache),
                "$": {
                    "param_mode": "packed",
                    "effect_mode": "none",
                },
            },
            "create_tir_paged_kv_cache": {
                "max_batch_size": int,
                "max_total_seq_len": int,
                "prefill_chunk_size": int,
                "page_size": int,
                "$": {
                    "param_mode": "none",
                    "effect_mode": "none",
                },
            },
        }
        return nn.spec.ModuleSpec.from_raw(mod_spec, self)


######################################################################
# Export the model to Relax IRModule
# ----------------------------------
# After defining the model architecture, we can export the model to the Relax IRModule.
# For demonstration, we only show the part of the model architecture. and parameters.

model_config = LlamaConfig()
model = LlamaForCausalLM(model_config)
model.to("float16")
mod, named_params = model.export_tvm(spec=model.get_default_spec())
prefill_str = mod["prefill"].script()
print(*prefill_str.split("\n")[3:20], sep="\n")  # Only show the first 10 lines for demonstration
print("        ...")

print("\nParameters:")
pprint(named_params[:5])  # Only show the first 5 parameters for demonstration

######################################################################
# Define Optimization Pipeline
# ----------------------------
# We define a series of optimization passes to optimize the model. The optimization pipeline
# is designed specifically for the LLMs.


@register_pipeline("opt_llm")
def _pipeline(  # pylint: disable=too-many-arguments
    ext_mods: list[nn.ExternModule] | None = None,
):
    ext_mods = ext_mods or []

    @tvm.transform.module_pass(opt_level=0)
    def _pipeline(mod: tvm.ir.IRModule, _ctx: tvm.transform.PassContext) -> tvm.ir.IRModule:
        seq = tvm.transform.Sequential(
            [
                # Phase 1. Passes on high-level operator graph
                # We can enable cublas for further optimization
                relax.transform.FuseTransposeMatmul(),
                # Phase 2. Lowering to TIR, inherited TVM Relax's official "zero" pipeline
                relax.transform.LegalizeOps(),
                relax.transform.AnnotateTIROpPattern(),
                relax.transform.FoldConstant(),
                relax.transform.FuseOps(),
                relax.transform.FuseTIR(),
                # Phase 3. Passes on TIR
                relax.transform.DeadCodeElimination(),
                # Phase 4. Low-level Optimizations
                dlight.ApplyDefaultSchedule(
                    dlight.gpu.Matmul(),
                    dlight.gpu.GEMV(),
                    dlight.gpu.Reduction(),
                    dlight.gpu.GeneralReduction(),
                    dlight.gpu.Fallback(),
                ),
                # Phase 5. Lowering to VM bytecode
                relax.transform.RewriteDataflowReshape(),
                relax.transform.ToNonDataflow(),
                relax.transform.RemovePurityChecking(),
                relax.transform.CallTIRRewrite(),
                relax.transform.StaticPlanBlockMemory(),
                relax.transform.RewriteCUDAGraph(),
                relax.transform.LowerAllocTensor(),
                relax.transform.KillAfterLastUse(),
                relax.transform.LowerRuntimeBuiltin(),
                relax.transform.VMShapeLower(),
                relax.transform.AttachGlobalSymbol(),
                relax.transform.AttachExternModules(ext_mods),
            ]
        )
        mod = seq(mod)
        return mod

    return _pipeline


with target:
    ex = tvm.compile(mod, target, relax_pipeline=relax.get_pipeline("opt_llm"))
    vm = relax.VirtualMachine(ex, dev)


######################################################################
# Prepare the model weights
# -------------------------
# We load the pre-trained weights from Hugging Face and prepare the model weights.
# The pre-trained weights are stored in the Hugging Face format. We need to load the weights
# and prepare the model parameters.
#
# .. note::
#
#   Note that we won't execute the following code in this tutorial because the pre-trained weights
#   are not available in the CI environment.
#


IS_IN_CI = os.getenv("CI", "") == "true"

HF_WEIGHT_PATH = None
# HF_WEIGHT_PATH = Path("/path/to/TinyLlama-1.1B-Chat-v1.0/")

if not IS_IN_CI:
    import numpy as np
    import safetensors.torch
    import torch

    if HF_WEIGHT_PATH is None or not HF_WEIGHT_PATH.exists():
        raise ValueError("Please set the HF_WEIGHT_PATH to the path of the pre-trained weights.")

    # Torch format weights
    param_dict = safetensors.torch.load_file(HF_WEIGHT_PATH / "model.safetensors", device="cpu")
    # Numpy format weights
    param_dict = {
        k: v.half().numpy() if v.dtype == torch.bfloat16 else v.numpy()
        for k, v in param_dict.items()
    }

    named_params = dict(named_params)
    for i in range(model_config.num_hidden_layers):
        # Add QKV in self attention
        attn = f"model.layers.{i}.self_attn"
        param_dict[f"{attn}.qkv_proj.weight"] = np.concatenate(
            [
                param_dict.pop(f"{attn}.q_proj.weight"),  # Pop the old parameters to save memory
                param_dict.pop(f"{attn}.k_proj.weight"),
                param_dict.pop(f"{attn}.v_proj.weight"),
            ],
            axis=0,
        )
        # Add gates in MLP
        mlp = f"model.layers.{i}.mlp"
        param_dict[f"{mlp}.gate_up_proj.weight"] = np.concatenate(
            [
                param_dict.pop(f"{mlp}.gate_proj.weight"),
                param_dict.pop(f"{mlp}.up_proj.weight"),
            ],
            axis=0,
        )

    # Convert params into ndarray
    params = [
        tvm.runtime.tensor(param_dict[k].astype("float16"), device=dev) for k in named_params.keys()
    ]


######################################################################
# Deploy the compiled model
# -------------------------
# After the model and weights are ready, we can deploy the compiled model on the target device.
# The language models inference includes two steps: prefill and decode. The prefill step is
# used to process the input tokens and store the KVCache. The decode step is used to generate
# the token until the end token is generated.


######################################################################
# Tokenization
# ~~~~~~~~~~~~
# The first step is to tokenize the input prompt and embed the tokens into the hidden states.
# The tokenization and embedding are the same as the original model. We use the HF tokenizer
# to tokenize the input prompt and embed the tokens into the hidden states.
# Note that different models require different tokenization and prompt format, please refer to
# the model documentation for the correct tokenization and prompt format.


if not IS_IN_CI:
    from transformers import AutoTokenizer

    tokenizer = AutoTokenizer.from_pretrained(HF_WEIGHT_PATH)
    messages = [
        {"role": "user", "content": "What's your name?"},
    ]
    prompt = tokenizer.apply_chat_template(messages)
    input_len = len(prompt)

    # Load prompt tokens into TVM ndarray on the target device
    tokens = tvm.runtime.tensor(np.array(prompt).astype("int32"), device=dev)

######################################################################
# Create the KVCache
# ~~~~~~~~~~~~~~~~~~
# Before starting the inference, we need to create the KVCache. The KVCache is used to store the
# key and value tensors for the attention layer. Apache TVM provides a PagedKVCache to store the
# key and value tensors. We create the PagedKVCache with the specified parameters.

if not IS_IN_CI:
    kv_cache = vm["create_tir_paged_kv_cache"](
        Shape([1]),  # max_batch_size=1
        Shape([2048]),  # max_total_seq_len=2048
        Shape([2048]),  # prefill_chunk_size=2048
        Shape([16]),  # page_size=16
    )


######################################################################
# Embedding
# ~~~~~~~~~
# The next step is to embed the tokens into the hidden states. We use the `embed` function
# compiled in the Relax IRModule to embed the tokens into the hidden states.

nd_view_func = tvm.get_global_func("vm.builtin.reshape")


def embed(tokens, params):
    _embed = vm["embed"](tokens, params)
    # Reshape hidden from [seq_len, hidden_size] to [1, seq_len, hidden_size]
    _embed = nd_view_func(_embed, Shape([1, _embed.shape[0], _embed.shape[1]]))
    return _embed


######################################################################
# Prefill
# ~~~~~~~
# Before running the forward pass, we first get some help functions for preparation.

add_sequence_func = tvm.get_global_func("vm.builtin.kv_state_add_sequence")
begin_forward_func = tvm.get_global_func("vm.builtin.kv_state_begin_forward")
end_forward_func = tvm.get_global_func("vm.builtin.kv_state_end_forward")

######################################################################
# As we are creating a new sequence, we need to call `add_sequence_func` to initialize
# the request. Additionally, we need to call `begin_forward_func` to start the forward pass,
# and `end_forward_func` to end the forward pass.

if not IS_IN_CI:
    seq_id = 0
    add_sequence_func(kv_cache, seq_id)
    hidden_states = embed(tokens, params)
    begin_forward_func(kv_cache, Shape([seq_id]), Shape([input_len]))
    logits, kv_cache = vm["prefill"](hidden_states, kv_cache, params)
    end_forward_func(kv_cache)

######################################################################
# Now we have the output logits from the prefill step. The logits are used to generate the token
# via sampling. Let's sample the token from the logits.
#
# In this tutorial, we simplify the sampling process and pick the token with the highest
# probability. In practice, we should sample the token based on the probability distribution.
# Also, to make the tutorial concise, we execute the sample process on CPU.


def sample_token(logits):
    logits_np = logits.numpy()
    return np.argmax(logits_np)


if not IS_IN_CI:
    last_token = sample_token(logits)
    output_tokens = [last_token]


######################################################################
# Decode
# ~~~~~~
# After the prefill step, we can start the decode step. The decode step is used to generate the
# token until the end token is generated. We use the `decode` function compiled in the Relax
# IRModule to generate the token.

if not IS_IN_CI:
    print("The generated token:")

    while last_token != tokenizer.eos_token_id:
        tokens = tvm.runtime.tensor(np.array([last_token]).astype("int32"), device=dev)
        hidden_states = embed(tokens, params)
        begin_forward_func(kv_cache, Shape([seq_id]), Shape([1]))
        logits, kv_cache = vm["decode"](hidden_states, kv_cache, params)

        end_forward_func(kv_cache)
        last_token = sample_token(logits)
        output_tokens.append(last_token)

    print(tokenizer.decode(output_tokens))
