chat.py

"""
Interactive chat with your GPT-2 model — Notebook version
Run Cell 1 and Cell 2 in order, then use the chat widget.
You can copy the code into colab cells. ensure you rename to your model path
"""

# ── Cell 1: Setup & load model ────────────────────────────────────────────────
import torch
import tiktoken
import ipywidgets as widgets
from IPython.display import display, HTML
from Architecture import LanguageModel
from GeneratorHF import HFTextGenerator

CHECKPOINT_PATH = "/content/drive/MyDrive/GPT2-small/refinedGPT2small.pth" #on google colab
DEVICE          = "cuda" if torch.cuda.is_available() else "cpu"

def load_model(checkpoint_path, device):
    print(f"Loading model from {checkpoint_path}...")
    ckpt       = torch.load(checkpoint_path, map_location=device, weights_only=False)
    config     = ckpt["config"]
    model      = LanguageModel(config)
    state_dict = ckpt["model_state_dict"]

    cleaned = {}
    for k, v in state_dict.items():
        for prefix in ["module.", "_orig_mod."]:
            while k.startswith(prefix):
                k = k[len(prefix):]
        cleaned[k] = v

    model.load_state_dict(cleaned)
    model.to(device)
    model.eval()

    params   = sum(p.numel() for p in model.parameters()) / 1e6
    val_loss = ckpt.get("loss", "?")
    print(f"  {params:.1f}M params | val_loss {val_loss} | device {device}")
    return model, config

model, config = load_model(CHECKPOINT_PATH, DEVICE)
enc           = tiktoken.get_encoding("gpt2")
gen           = HFTextGenerator(model, enc, DEVICE, context_size=config["context_length"])
print("Ready.")


# ── Cell 2: Chat widget ───────────────────────────────────────────────────────

# ── Sampling controls ─────────────────────────────────────────────────────────
temp_slider = widgets.FloatSlider(
    value=0.8, min=0.1, max=2.0, step=0.05,
    description="Temperature",
    style={"description_width": "90px"},
    layout=widgets.Layout(width="400px")
)
topk_slider = widgets.IntSlider(
    value=40, min=1, max=200, step=1,
    description="Top-k",
    style={"description_width": "90px"},
    layout=widgets.Layout(width="400px")
)
tokens_slider = widgets.IntSlider(
    value=150, min=10, max=500, step=10,
    description="Max tokens",
    style={"description_width": "90px"},
    layout=widgets.Layout(width="400px")
)

# ── Input & buttons ───────────────────────────────────────────────────────────
prompt_box = widgets.Textarea(
    placeholder="Type your prompt here...",
    layout=widgets.Layout(width="700px", height="70px")
)
generate_btn = widgets.Button(
    description="Generate",
    button_style="primary",
    layout=widgets.Layout(width="120px")
)
clear_btn = widgets.Button(
    description="Clear",
    button_style="warning",
    layout=widgets.Layout(width="80px")
)

# ── Output area ───────────────────────────────────────────────────────────────
output_area = widgets.Output()

def on_generate(b):
    prompt = prompt_box.value.strip()
    if not prompt:
        return

    with output_area:
        print(f"\nYOU   > {prompt}")
        print("MODEL > ", end="", flush=True)

        continuation = gen.generate(
            prompt,
            max_new_tokens=tokens_slider.value,
            temperature=temp_slider.value,
            top_k=topk_slider.value,
        )
        print(continuation)
        print("-" * 70)

def on_clear(b):
    output_area.clear_output()
    prompt_box.value = ""

generate_btn.on_click(on_generate)
clear_btn.on_click(on_clear)

# ── Layout ────────────────────────────────────────────────────────────────────
controls = widgets.VBox([
    widgets.HTML("<b>Sampling settings</b>"),
    temp_slider,
    topk_slider,
    tokens_slider,
])
buttons = widgets.HBox([generate_btn, clear_btn])
ui      = widgets.VBox([
    widgets.HTML("<h3>GPT-2 Small — Chat</h3>"),
    controls,
    widgets.HTML("<br><b>Prompt</b>"),
    prompt_box,
    buttons,
    widgets.HTML("<br><b>Output</b>"),
    output_area,
])

display(ui)