app.py

# ============================================================
# ⚡ Semantic Intent Router (MiniLM)
# Zero-shot • No training • Sub-second • HF Free CPU
# ============================================================

import json
import time
import math
from typing import Dict, List, Any

import torch
import gradio as gr
from sentence_transformers import SentenceTransformer, util

# ============================================================
# CONFIG
# ============================================================

MODEL_NAME = "sentence-transformers/all-MiniLM-L6-v2"
MIN_SCORE = 0.05
MAX_EXAMPLES = 20

# ============================================================
# LOAD MODEL
# ============================================================

print("Loading MiniLM model...")
model = SentenceTransformer(MODEL_NAME, device="cpu")
print("Model loaded")

# ============================================================
# HELPERS
# ============================================================

def softmax(scores: Dict[str, float]) -> Dict[str, float]:
    if not scores:
        return {}

    max_val = max(scores.values())
    exp_scores = {k: math.exp(v - max_val) for k, v in scores.items()}
    total = sum(exp_scores.values())

    return {k: v / total for k, v in exp_scores.items()}


def parse_labels(raw: Any) -> Dict[str, List[str]]:
    """
    Accepts dict (Gradio JSON) or JSON string.
    Returns clean label -> examples mapping.
    """

    if isinstance(raw, str):
        try:
            raw = json.loads(raw)
        except Exception as e:
            return {"__error__": f"Invalid JSON: {e}"}

    if not isinstance(raw, dict):
        return {"__error__": "Labels must be a JSON object"}

    cleaned = {}

    for label, examples in raw.items():
        if not isinstance(label, str):
            continue
        if not isinstance(examples, list):
            continue

        ex = [
            str(x).strip()
            for x in examples
            if isinstance(x, (str, int, float)) and str(x).strip()
        ][:MAX_EXAMPLES]

        if ex:
            cleaned[label] = ex

    if not cleaned:
        return {"__error__": "No valid labels found"}

    return cleaned


# ============================================================
# CLASSIFIER CORE
# ============================================================

def classify(text: str, raw_labels: Any) -> Dict[str, Any]:
    start = time.time()

    if not text or not text.strip():
        return {"error": "Empty input"}

    labels = parse_labels(raw_labels)
    if "__error__" in labels:
        return {"error": labels["__error__"]}

    text_emb = model.encode(text, convert_to_tensor=True)

    scores = {}

    for label, examples in labels.items():
        example_embs = model.encode(examples, convert_to_tensor=True)
        sims = util.cos_sim(text_emb, example_embs)[0]
        score = float(torch.max(sims).item())

        if score >= MIN_SCORE:
            scores[label] = score

    if not scores:
        return {
            "text": text,
            "top_intent": None,
            "scores": {},
            "latency_ms": round((time.time() - start) * 1000, 2),
        }

    scores = softmax(scores)
    top_intent = max(scores, key=scores.get)

    return {
        "text": text,
        "top_intent": top_intent,
        "scores": dict(sorted(scores.items(), key=lambda x: -x[1])),
        "latency_ms": round((time.time() - start) * 1000, 2),
    }


# ============================================================
# DEFAULT LABELS
# ============================================================

DEFAULT_LABELS = {
    "chat": [
        "say hello",
        "casual talk",
        "how are you"
    ],
    "image_generation": [
        "generate an image",
        "draw a picture",
        "create artwork"
    ],
    "action": [
        "set a timer",
        "create a reminder"
    ],
    "code": [
        "write code",
        "debug program"
    ],
    "search": [
        "search online",
        "find information"
    ]
}

# ============================================================
# GRADIO UI
# ============================================================

with gr.Blocks(title="⚡ Semantic Intent Router") as demo:
    gr.Markdown(
        "# ⚡ Semantic Intent Router\n"
        "MiniLM semantic classifier · No training · Sub-second\n\n"
        "• Edit labels freely\n"
        "• Add examples per label\n"
        "• Used for MPC / system-prompt routing\n"
    )

    user_input = gr.Textbox(
        label="User Input",
        placeholder="Type anything…",
        lines=2
    )

    labels_input = gr.JSON(
        label="Labels & Examples (editable)",
        value=DEFAULT_LABELS
    )

    output = gr.JSON(label="Routing Result")

    classify_btn = gr.Button("Classify", variant="primary")

    classify_btn.click(
        fn=classify,
        inputs=[user_input, labels_input],
        outputs=output
    )

    gr.Markdown(
        "### API Usage\n"
        "POST to this Space endpoint with:\n\n"
        "`{\"data\": [\"your text\", {\"label\": [\"example\"]}]}`\n"
    )

# ============================================================
# LAUNCH
# ============================================================

if __name__ == "__main__":
    demo.launch(
        share=True
    )