import argparse
import os
import shutil

import torch
from datasets import load_dataset
from transformers import AutoModelForCausalLM, AutoTokenizer
from huggingface_hub import HfApi, create_repo
from huggingface_hub.constants import HF_HUB_CACHE

from llmcompressor import oneshot
from llmcompressor.modifiers.transform import AWQModifier
from llmcompressor.modifiers.transform.awq import AWQMapping
from llmcompressor.modifiers.quantization import QuantizationModifier


MODEL_ID = "Qwen/Qwen3-8B"


QWEN_AWQ_MAPPINGS = [
    AWQMapping(
        "re:.*input_layernorm",
        ["re:.*q_proj", "re:.*k_proj", "re:.*v_proj"],
    ),
    AWQMapping(
        "re:.*v_proj",
        ["re:.*o_proj"],
    ),
    AWQMapping(
        "re:.*post_attention_layernorm",
        ["re:.*gate_proj", "re:.*up_proj"],
    ),
    AWQMapping(
        "re:.*up_proj",
        ["re:.*down_proj"],
    ),
]


SCHEMES = {
    "fp8": "FP8_BLOCK",
    "nvfp4": "NVFP4",
    "mxfp4": "MXFP4",
    "mxfp8": "MXFP8",
}


def purge_base_cache(model_id: str):
    """Delete the downloaded base-model snapshot from the HF hub cache.

    Safe to call only after the model has been fully loaded into (GPU) memory,
    since the on-disk safetensors are no longer needed to quantize and save.
    """
    org_name = model_id.replace("/", "--")
    cache_dir = os.path.join(HF_HUB_CACHE, f"models--{org_name}")
    if os.path.isdir(cache_dir):
        print(f"Purging base-model cache: {cache_dir}")
        shutil.rmtree(cache_dir, ignore_errors=True)
    else:
        print(f"No base-model cache found at: {cache_dir}")


def load_wikitext2(num_samples: int):
    ds = load_dataset(
        "Salesforce/wikitext",
        "wikitext-2-raw-v1",
        split="train",
    )

    ds = ds.filter(lambda x: x["text"] is not None and len(x["text"].strip()) > 64)
    ds = ds.shuffle(seed=42)
    ds = ds.select(range(min(num_samples, len(ds))))

    return ds


def build_hub_repo_id(
    model_id: str,
    scheme_name: str,
    namespace: str | None = None,
    token: str | None = None,
):
    model_name = model_id.split("/")[-1]
    repo_name = f"{model_name}-{scheme_name.upper()}-AWQ-wikitext2"

    if namespace is None:
        api = HfApi(token=token)
        user_info = api.whoami(token=token)
        namespace = user_info["name"]

    return f"{namespace}/{repo_name}"


def upload_to_hub(
    local_dir: str,
    repo_id: str,
    private: bool,
    commit_message: str,
    token: str | None = None,
):
    print(f"Creating/checking HF repo: {repo_id}")

    create_repo(
        repo_id=repo_id,
        repo_type="model",
        private=private,
        exist_ok=True,
        token=token,
    )

    api = HfApi(token=token)

    print(f"Uploading local checkpoint from: {local_dir}")
    print(f"Target repo: https://huggingface.co/{repo_id}")

    api.upload_folder(
        folder_path=local_dir,
        repo_id=repo_id,
        repo_type="model",
        commit_message=commit_message,
        token=token,
    )

    print("Upload complete")


def main():
    parser = argparse.ArgumentParser()

    parser.add_argument(
        "--scheme",
        choices=["fp8", "nvfp4", "mxfp4", "mxfp8"],
        required=True,
    )

    parser.add_argument("--model-id", default=MODEL_ID)
    parser.add_argument("--num-calibration-samples", type=int, default=512)
    parser.add_argument("--max-seq-length", type=int, default=2048)
    parser.add_argument("--output-dir", default=None)

    parser.add_argument(
        "--upload-to-hub",
        action="store_true",
        help="Upload saved compressed checkpoint to Hugging Face Hub",
    )

    parser.add_argument(
        "--purge-base-after-load",
        action="store_true",
        help="Delete the base-model HF cache after loading it into memory "
        "(frees disk before saving large quantized outputs).",
    )

    parser.add_argument(
        "--delete-local-after-upload",
        action="store_true",
        help="Delete the local compressed checkpoint after a successful upload.",
    )

    parser.add_argument(
        "--hub-namespace",
        default=None,
        help="HF username/org. If not passed, uses logged-in HF user.",
    )

    parser.add_argument(
        "--private",
        action="store_true",
        help="Create Hugging Face repo as private",
    )

    parser.add_argument(
        "--hf-token",
        default=None,
        help="Optional HF token. Prefer HF_TOKEN env var or huggingface-cli login.",
    )

    args = parser.parse_args()

    scheme = SCHEMES[args.scheme]

    model_name = args.model_id.split("/")[-1]
    output_dir = args.output_dir or f"{model_name}-{args.scheme.upper()}-AWQ-wikitext2"

    print(f"Loading model: {args.model_id}")

    # Shard the model across all visible GPUs (no CPU offloading). With two
    # 97GB GPUs, accelerate places different decoder layers on each device,
    # leaving ample headroom for the AWQ activation cache so we can run the
    # full-quality calibration footprint.
    model = AutoModelForCausalLM.from_pretrained(
        args.model_id,
        torch_dtype="auto",
        device_map="auto",
        trust_remote_code=True,
    )

    tokenizer = AutoTokenizer.from_pretrained(
        args.model_id,
        trust_remote_code=True,
    )

    if tokenizer.pad_token is None:
        tokenizer.pad_token = tokenizer.eos_token

    if args.purge_base_after_load:
        purge_base_cache(args.model_id)

    print("Loading WikiText-2 calibration dataset")

    calib_ds = load_wikitext2(args.num_calibration_samples)

    recipe = [
        AWQModifier(
            mappings=QWEN_AWQ_MAPPINGS,
        ),
        QuantizationModifier(
            targets="Linear",
            scheme=scheme,
            ignore=["lm_head"],
        ),
    ]

    print(f"Running AWQ + {scheme} quantization")

    oneshot(
        model=model,
        tokenizer=tokenizer,
        dataset=calib_ds,
        recipe=recipe,
        max_seq_length=args.max_seq_length,
        num_calibration_samples=args.num_calibration_samples,
    )

    print(f"Saving compressed model locally to: {output_dir}")

    model.save_pretrained(
        output_dir,
        save_compressed=True,
    )

    tokenizer.save_pretrained(output_dir)

    if args.upload_to_hub:
        hf_token = args.hf_token or os.environ.get("HF_TOKEN")

        hub_repo_id = build_hub_repo_id(
            model_id=args.model_id,
            scheme_name=args.scheme,
            namespace=args.hub_namespace,
            token=hf_token,
        )

        upload_to_hub(
            local_dir=output_dir,
            repo_id=hub_repo_id,
            private=args.private,
            commit_message=(
                f"Upload {args.model_id} {args.scheme.upper()} "
                "AWQ compressed checkpoint calibrated on WikiText-2"
            ),
            token=hf_token,
        )

        if args.delete_local_after_upload:
            print(f"Deleting local checkpoint after upload: {output_dir}")
            shutil.rmtree(output_dir, ignore_errors=True)

    print("Done")


if __name__ == "__main__":
    main()


#python quantize_my_model.py --scheme fp8 --upload-to-hub --hub-namespace jaytonde5
#python quantize_my_model.py --scheme nvfp4 --upload-to-hub --hub-namespace jaytonde5
#python quantize_my_model.py --scheme mxfp4 --upload-to-hub --hub-namespace jaytonde5
#python quantize_my_model.py --scheme mxfp8 --upload-to-hub --hub-namespace jaytonde5