# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""
Create a reduced-layer version of the Maverick model for testing purposes.

This script creates a new model with fewer layers by:
1. Loading the original Maverick model configuration
2. Creating a reduced configuration
3. Generating compatible safetensors files with appropriate weights
4. Creating the necessary index files for vLLM compatibility
"""

import json
import shutil
from pathlib import Path
from typing import Any

import pytest
import torch
from safetensors.torch import save_file
from transformers import (AutoConfig, AutoProcessor, AutoTokenizer,
                          GenerationConfig)

from vllm import LLM, SamplingParams

# Sample prompts for testing
PROMPTS: list[str] = [
    "Hello, my name is",
    "The president of the United States is",
    "The capital of France is",
    "The future of AI is",
]


def run_maverick_serving(model: str):
    """Test Llama-4-Maverick model with vLLM LLM class using CLI equivalent
    options with reduced layers.
    """

    try:
        sampling_params = SamplingParams(temperature=0.8, top_p=0.95)

        llm = LLM(
            model=model,
            max_model_len=2048,
            enforce_eager=True,
            tensor_parallel_size=8,
            enable_expert_parallel=True,
            trust_remote_code=True,
            gpu_memory_utilization=0.4,
            kv_cache_dtype="fp8",
        )

        outputs = llm.generate(PROMPTS, sampling_params)

        # Print the outputs
        print("\nGenerated Outputs:\n" + "-" * 60)
        for output in outputs:
            prompt = output.prompt
            generated_text = output.outputs[0].text
            print(f"Prompt:    {prompt!r}")
            print(f"Output:    {generated_text!r}")
            print("-" * 60)

    except Exception as e:
        print(f"Error initializing or running model: {e}")
        raise


def create_reduced_maverick_model(
    original_model_name:
    str = "meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8",
    output_dir: str = "/tmp/reduced_maverick",
    text_layers: int = 4,
    num_experts: int = 4,
    vision_layers: int = 2,
    force_recreate: bool = False,
) -> str:
    """
    Create a reduced-layer version of the Maverick model.

    Args:
        original_model_name: Name of the original Maverick model
        output_dir: Directory to save the reduced model
        text_layers: Number of text transformer layers
        num_experts: Number of experts per layer
        vision_layers: Number of vision transformer layers
        force_recreate: Whether to recreate if output_dir already exists

    Returns:
        Path to the created reduced model directory
    """

    print(
        f"Creating reduced Maverick model with {text_layers} text layers and "
        f"{vision_layers} vision layers...")

    # Create output directory
    output_path = Path(output_dir)
    if output_path.exists():
        if force_recreate:
            shutil.rmtree(output_path)
        else:
            print(f"Output directory {output_dir} already exists. "
                  "Use --force-recreate to overwrite.")
            return str(output_path)

    output_path.mkdir(parents=True, exist_ok=True)

    try:
        print("Loading original model configuration...")
        original_config = AutoConfig.from_pretrained(original_model_name,
                                                     trust_remote_code=True)

        print("Creating reduced configuration...")
        reduced_config = create_reduced_config(original_config, text_layers,
                                               num_experts, vision_layers)

        config_path = output_path / "config.json"
        with open(config_path, "w") as f:
            json.dump(reduced_config, f, indent=2)
        print(f"Saved reduced config to {config_path}")

        print("Copying tokenizer files...")
        copy_tokenizer_files(original_model_name, output_path)

        print("Creating reduced safetensors files...")
        create_reduced_safetensors(original_config, reduced_config,
                                   output_path)

        print("Creating preprocessor config...")
        create_preprocessor_config(original_config, output_path)

        try:
            gen_config = GenerationConfig.from_pretrained(original_model_name)
            gen_config.save_pretrained(output_path)
            print("Copied generation config")
        except Exception as e:
            print(f"Could not copy generation config: {e}")

        print(f"Successfully created reduced Maverick model at {output_path}")
        return str(output_path)

    except Exception as e:
        print(f"Error creating reduced model: {e}")
        # Clean up on failure
        if output_path.exists():
            shutil.rmtree(output_path)
        raise


def create_reduced_config(original_config: Any, text_layers: int,
                          num_experts: int,
                          vision_layers: int) -> dict[str, Any]:
    """Create a reduced configuration based on the original."""

    # Convert config to dictionary
    config_dict = original_config.to_dict()

    # Reduce text layers
    if "text_config" in config_dict:
        original_text_layers = config_dict["text_config"]["num_hidden_layers"]
        config_dict["text_config"]["num_hidden_layers"] = text_layers
        print(
            f"Reduced text layers from {original_text_layers} to {text_layers}"
        )

        original_num_experts = config_dict["text_config"]["num_local_experts"]
        config_dict["text_config"]["num_local_experts"] = num_experts
        print(
            f"Reduced num experts from {original_num_experts} to {num_experts}"
        )

        hidden_dim_divisor = 4

        original_hidden_size = config_dict["text_config"]["hidden_size"]
        new_hidden_size = original_hidden_size // hidden_dim_divisor
        config_dict["text_config"]["hidden_size"] = new_hidden_size
        print(f"Reduced hidden size from {original_hidden_size} to "
              f"{new_hidden_size}")

        original_head_dim = config_dict["text_config"]["head_dim"]
        new_head_dim = original_head_dim // hidden_dim_divisor
        config_dict["text_config"]["head_dim"] = new_head_dim
        print(f"Reduced head dim from {original_head_dim} to {new_head_dim}")

    # Reduce vision layers
    if "vision_config" in config_dict:
        original_vision_layers = config_dict["vision_config"][
            "num_hidden_layers"]
        config_dict["vision_config"]["num_hidden_layers"] = vision_layers
        print(f"Reduced vision layers from {original_vision_layers} "
              f"to {vision_layers}")

    # Update model name to indicate it's a reduced version
    config_dict["_name_or_path"] = (
        f"reduced_maverick_{text_layers}t_{vision_layers}v")

    return config_dict


def copy_tokenizer_files(original_model_name: str, output_path: Path) -> None:
    """Copy tokenizer files from the original model."""

    try:
        tokenizer = AutoTokenizer.from_pretrained(original_model_name,
                                                  trust_remote_code=True)
        tokenizer.save_pretrained(output_path)
        print("Tokenizer files copied successfully")
    except Exception as e:
        print(f"Warning: Could not copy tokenizer files: {e}")


def create_preprocessor_config(original_config: Any,
                               output_path: Path) -> None:
    """Create preprocessor_config.json for multimodal model."""

    # Try to load the original preprocessor config
    try:
        processor = AutoProcessor.from_pretrained(
            original_config._name_or_path
            or "meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8",
            trust_remote_code=True,
        )
        processor.save_pretrained(output_path)
        print("Copied original preprocessor config")
        return
    except Exception as e:
        print(f"Could not copy original preprocessor config: {e}")
        raise


def create_reduced_safetensors(original_config: Any, reduced_config: dict[str,
                                                                          Any],
                               output_path: Path) -> None:
    """Create safetensors files with weights for the reduced model."""

    print("Generating synthetic weights for reduced model...")

    text_config = reduced_config["text_config"]
    vision_config = reduced_config["vision_config"]

    weights = {}

    print("Creating text model weights...")
    weights.update(create_text_model_weights(text_config))

    print("Creating vision model weights...")
    weights.update(create_vision_model_weights(vision_config))

    print("Creating shared model weights...")
    weights.update(create_shared_weights(text_config, vision_config))

    print("Saving weights to safetensors files...")
    save_weights_to_safetensors(weights, output_path)


def create_text_model_weights(
        text_config: dict[str, Any]) -> dict[str, torch.Tensor]:
    """Create synthetic weights for the text model with MoE structure."""

    weights = {}

    vocab_size = text_config["vocab_size"]
    hidden_size = text_config["hidden_size"]
    intermediate_size = text_config["intermediate_size"]
    intermediate_size_mlp = text_config["intermediate_size_mlp"]
    num_layers = text_config["num_hidden_layers"]
    num_attention_heads = text_config["num_attention_heads"]
    num_key_value_heads = text_config.get("num_key_value_heads",
                                          num_attention_heads)

    # MoE specific parameters
    num_experts = text_config.get("num_local_experts")
    assert (num_experts
            is not None), "num_local_experts must be specified for MoE"

    head_dim = hidden_size // num_attention_heads

    # Embedding layers
    weights["language_model.model.embed_tokens.weight"] = torch.randn(
        vocab_size, hidden_size, dtype=torch.float16)

    # Transformer layers
    for layer_idx in range(num_layers):
        layer_prefix = f"language_model.model.layers.{layer_idx}"
        print(f"Creating weights for layer {layer_prefix}...")

        # Self-attention weights (separate q, k, v projections)
        weights[f"{layer_prefix}.self_attn.q_proj.weight"] = torch.randn(
            hidden_size, num_attention_heads * head_dim, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.k_proj.weight"] = torch.randn(
            hidden_size, num_key_value_heads * head_dim, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.v_proj.weight"] = torch.randn(
            num_key_value_heads * head_dim, hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.o_proj.weight"] = torch.randn(
            hidden_size, num_attention_heads * head_dim, dtype=torch.bfloat16)
        print("Self-attention weights created.")

        # Feed-forward weights - MoE pattern based on interleave_moe_layer_step
        # For interleave_moe_layer_step=2: layers 1,3,5,... are MoE, layers
        # 0,2,4,... are dense
        interleave_step = text_config.get("interleave_moe_layer_step", 1)
        is_moe_layer = (interleave_step > 0
                        and (layer_idx + 1) % interleave_step == 0)

        if is_moe_layer:
            # MoE layer structure
            # 1. Router weights
            weights[
                f"{layer_prefix}.feed_forward.router.weight"] = torch.randn(
                    num_experts, hidden_size, dtype=torch.float16)

            # 2. Individual expert weights (not fused)
            for expert_idx in range(num_experts):
                expert_prefix = (
                    f"{layer_prefix}.feed_forward.experts.{expert_idx}")

                weights[f"{expert_prefix}.gate_proj.weight"] = torch.randn(
                    intermediate_size, hidden_size, dtype=torch.bfloat16)
                weights[f"{expert_prefix}.up_proj.weight"] = torch.randn(
                    intermediate_size, hidden_size, dtype=torch.bfloat16)
                weights[f"{expert_prefix}.down_proj.weight"] = torch.randn(
                    hidden_size, intermediate_size, dtype=torch.bfloat16)

                # Expert weight scales (FP8 quantization)
                weights[
                    f"{expert_prefix}.gate_proj.weight_scale"] = torch.ones(
                        intermediate_size, 1, dtype=torch.bfloat16)
                weights[f"{expert_prefix}.up_proj.weight_scale"] = torch.ones(
                    intermediate_size, 1, dtype=torch.bfloat16)
                weights[
                    f"{expert_prefix}.down_proj.weight_scale"] = torch.ones(
                        hidden_size, 1, dtype=torch.bfloat16)

            # 3. Shared expert weights
            shared_expert_prefix = f"{layer_prefix}.feed_forward.shared_expert"
            weights[f"{shared_expert_prefix}.gate_proj.weight"] = torch.randn(
                intermediate_size, hidden_size, dtype=torch.bfloat16)
            weights[f"{shared_expert_prefix}.up_proj.weight"] = torch.randn(
                intermediate_size, hidden_size, dtype=torch.bfloat16)
            weights[f"{shared_expert_prefix}.down_proj.weight"] = torch.randn(
                hidden_size, intermediate_size, dtype=torch.bfloat16)
            print(f"MoE feed-forward weights created for layer {layer_idx}.")
        else:
            # Dense layer structure
            weights[f"{layer_prefix}.feed_forward.gate_proj.weight"] = (
                torch.randn(intermediate_size_mlp,
                            hidden_size,
                            dtype=torch.bfloat16))
            weights[f"{layer_prefix}.feed_forward.up_proj.weight"] = (
                torch.randn(intermediate_size_mlp,
                            hidden_size,
                            dtype=torch.bfloat16))
            weights[f"{layer_prefix}.feed_forward.down_proj.weight"] = (
                torch.randn(hidden_size,
                            intermediate_size_mlp,
                            dtype=torch.bfloat16))
            print(f"Dense feed-forward weights created for layer {layer_idx}.")

        # Layer norms
        weights[f"{layer_prefix}.input_layernorm.weight"] = torch.ones(
            hidden_size, dtype=torch.bfloat16)
        weights[
            f"{layer_prefix}.post_attention_layernorm.weight"] = torch.ones(
                hidden_size, dtype=torch.bfloat16)
        print("Layer norms created.")

    # Final layer norm and output projection
    weights["language_model.model.norm.weight"] = torch.ones(
        hidden_size, dtype=torch.bfloat16)
    weights["language_model.lm_head.weight"] = torch.randn(
        vocab_size, hidden_size, dtype=torch.bfloat16)

    return weights


def create_vision_model_weights(
        vision_config: dict[str, Any]) -> dict[str, torch.Tensor]:
    """Create synthetic weights for the vision model."""

    weights = {}

    hidden_size = vision_config["hidden_size"]
    intermediate_size = vision_config["intermediate_size"]
    num_layers = vision_config["num_hidden_layers"]

    # Vision transformer layers
    for layer_idx in range(num_layers):
        layer_prefix = f"vision_model.model.layers.{layer_idx}"

        weights[f"{layer_prefix}.self_attn.q_proj.weight"] = torch.randn(
            hidden_size, hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.q_proj.bias"] = torch.zeros(
            hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.k_proj.weight"] = torch.randn(
            hidden_size, hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.k_proj.bias"] = torch.zeros(
            hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.v_proj.weight"] = torch.randn(
            hidden_size, hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.v_proj.bias"] = torch.zeros(
            hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.o_proj.weight"] = torch.randn(
            hidden_size, hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.self_attn.o_proj.bias"] = torch.zeros(
            hidden_size, dtype=torch.bfloat16)

        weights[f"{layer_prefix}.mlp.fc1.weight"] = torch.randn(
            intermediate_size, hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.mlp.fc1.bias"] = torch.zeros(
            intermediate_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.mlp.fc2.weight"] = torch.randn(
            hidden_size, intermediate_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.mlp.fc2.bias"] = torch.zeros(
            hidden_size, dtype=torch.bfloat16)

        weights[f"{layer_prefix}.input_layernorm.weight"] = torch.ones(
            hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.input_layernorm.bias"] = torch.zeros(
            hidden_size, dtype=torch.bfloat16)
        weights[
            f"{layer_prefix}.post_attention_layernorm.weight"] = torch.ones(
                hidden_size, dtype=torch.bfloat16)
        weights[f"{layer_prefix}.post_attention_layernorm.bias"] = torch.zeros(
            hidden_size, dtype=torch.bfloat16)

    return weights


def create_shared_weights(
        text_config: dict[str, Any],
        vision_config: dict[str, Any]) -> dict[str, torch.Tensor]:
    """Create weights for shared components (vision-language connector)"""

    weights = {}

    text_hidden_size = text_config["hidden_size"]
    projector_input_dim = vision_config["projector_input_dim"]

    # Vision-language connector (projects vision features to text space)
    weights["multi_modal_projector.linear_1.weight"] = torch.randn(
        text_hidden_size, projector_input_dim, dtype=torch.bfloat16)

    return weights


def save_weights_to_safetensors(weights: dict[str, torch.Tensor],
                                output_path: Path) -> None:
    """Save weights to safetensors files and create index."""

    # Determine how to shard the weights
    max_shard_size = 5 * 1024 * 1024 * 1024  # 5GB per shard

    # Calculate sizes and create shards
    shards = []
    current_shard: dict[str, torch.Tensor] = {}
    current_size = 0

    for name, tensor in weights.items():
        tensor_size = tensor.numel() * tensor.element_size()

        if current_size + tensor_size > max_shard_size and current_shard:
            shards.append(current_shard)
            current_shard = {}
            current_size = 0

        current_shard[name] = tensor
        current_size += tensor_size

    if current_shard:
        shards.append(current_shard)

    # Save shards and create index
    weight_map = {}

    if len(shards) == 1:
        # Single file
        filename = "model.safetensors"
        save_file(shards[0], output_path / filename)
        weight_map = {name: filename for name in shards[0]}
        print(f"Saved weights to single file: {filename}")
    else:
        # Multiple shards
        for i, shard in enumerate(shards):
            filename = f"model-{i+1:05d}-of-{len(shards):05d}.safetensors"
            save_file(shard, output_path / filename)
            for name in shard:
                weight_map[name] = filename
            print(f"Saved shard {i+1}/{len(shards)}: {filename}")

    # Create index file
    index_data = {
        "metadata": {
            "total_size":
            sum(tensor.numel() * tensor.element_size()
                for tensor in weights.values())
        },
        "weight_map": weight_map,
    }

    index_path = output_path / "model.safetensors.index.json"
    with open(index_path, "w") as f:
        json.dump(index_data, f, indent=2)

    print(f"Created index file: {index_path}")
    print(f"Total model size: "
          f"{index_data['metadata']['total_size'] / (1024**3):.2f} GB")


def run_reduced_model(model_path: str,
                      should_profile: bool = False,
                      **kwargs) -> None:
    """Test the created reduced model with vLLM."""

    print(f"\nTesting reduced model at {model_path}...")

    llm = LLM(
        model=model_path,
        trust_remote_code=True,
        max_model_len=512,  # Small context for testing
        gpu_memory_utilization=0.3,  # Conservative memory usage
        **kwargs,
    )

    sampling_params = SamplingParams(temperature=0.8,
                                     top_p=0.95,
                                     max_tokens=50)

    if should_profile:
        llm.start_profile()
    outputs = llm.generate(PROMPTS, sampling_params)
    if should_profile:
        llm.stop_profile()

    print("Test generation successful!")
    for output in outputs:
        print(f"Prompt: {output.prompt}")
        print(f"Output: "
              f"{output.outputs[0].text}")
        print("-" * 40)


@pytest.mark.parametrize(
    "original_model_name,text_layers,num_experts,vision_layers,",
    [("meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8", 4, 4, 2)])
@pytest.mark.parametrize("enforce_eager", [True, False])
@pytest.mark.parametrize("tp,ep", [(2, True)])
@pytest.mark.skipif(not torch.cuda.is_available(), reason="CUDA not available")
def test_dummy_maverick(
    original_model_name: str,
    text_layers: int,
    num_experts: int,
    vision_layers: int,
    enforce_eager: bool,
    tp: int,
    ep: bool,
    output_dir: str = "/tmp/reduced_maverick",
    force_recreate: bool = True,
    profile: bool = False,
) -> None:
    model_path = create_reduced_maverick_model(
        original_model_name=original_model_name,
        output_dir=output_dir,
        text_layers=text_layers,
        num_experts=num_experts,
        vision_layers=vision_layers,
        force_recreate=force_recreate,
    )

    print(f"\nReduced model created successfully at: {model_path}")

    run_reduced_model(model_path=model_path,
                      should_profile=profile,
                      enforce_eager=enforce_eager,
                      tensor_parallel_size=tp,
                      enable_expert_parallel=ep)


def main():
    """Main function to create and test the reduced model."""

    import argparse

    parser = argparse.ArgumentParser(
        description="Create a reduced-layer Maverick model")
    parser.add_argument(
        "--output-dir",
        default="/tmp/reduced_maverick",
        help="Output directory for the reduced model",
    )
    parser.add_argument(
        "--text-layers",
        type=int,
        default=4,
        help="Number of text transformer layers",
    )
    parser.add_argument("--num-experts",
                        type=int,
                        default=4,
                        help="Number of experts")
    parser.add_argument(
        "--vision-layers",
        type=int,
        default=2,
        help="Number of vision transformer layers",
    )
    parser.add_argument(
        "--force-recreate",
        action="store_true",
        help="Force recreation if output directory exists",
    )
    parser.add_argument("--test",
                        action="store_true",
                        help="Test the created model with vLLM")
    parser.add_argument("--profile",
                        action="store_true",
                        help="Profile the created model with vLLM")
    parser.add_argument(
        "--test-original",
        action="store_true",
        help="Test the original model with vLLM",
    )
    parser.add_argument(
        "--original-model",
        default="meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8",
        help="Original model name to base the reduction on",
    )

    args = parser.parse_args()

    if args.test:
        test_dummy_maverick(original_model_name=args.original_model,
                            output_dir=args.output_dir,
                            text_layers=args.text_layers,
                            num_experts=args.num_experts,
                            vision_layers=args.vision_layers,
                            force_recreate=args.force_recreate,
                            tp=2,
                            ep=True,
                            enforce_eager=True,
                            profile=args.profile)

    if args.test_original:
        run_maverick_serving(args.original_model)


if __name__ == "__main__":
    exit(main())
