app.py

"""dcode - Text to Polargraph Gcode via Stable Diffusion"""

import re
import os
import json
import gradio as gr
import torch
import torch.nn as nn
from pathlib import Path
import spaces

# Machine limits
BOUNDS = {"left": -420.5, "right": 420.5, "top": 594.5, "bottom": -594.5}

# Model cache
_model = None


# ============================================================================
# V3 DECODER ARCHITECTURE
# ============================================================================

class GcodeDecoderConfigV3:
    """Config for v3 decoder architecture."""
    
    def __init__(
        self,
        latent_channels: int = 4,
        latent_size: int = 64,
        hidden_size: int = 1024,
        num_layers: int = 12,
        num_heads: int = 16,
        vocab_size: int = 8192,
        max_seq_len: int = 2048,
        dropout: float = 0.1,
        ffn_mult: int = 4,
    ):
        self.latent_channels = latent_channels
        self.latent_size = latent_size
        self.hidden_size = hidden_size
        self.num_layers = num_layers
        self.num_heads = num_heads
        self.vocab_size = vocab_size
        self.max_seq_len = max_seq_len
        self.dropout = dropout
        self.ffn_mult = ffn_mult


class CNNLatentProjector(nn.Module):
    """CNN-based latent projector preserving spatial structure."""
    
    def __init__(self, config: GcodeDecoderConfigV3):
        super().__init__()
        
        self.cnn = nn.Sequential(
            nn.Conv2d(config.latent_channels, 64, 3, stride=2, padding=1),
            nn.LayerNorm([64, 32, 32]),
            nn.GELU(),
            nn.Conv2d(64, 128, 3, stride=2, padding=1),
            nn.LayerNorm([128, 16, 16]),
            nn.GELU(),
            nn.Conv2d(128, 256, 3, stride=2, padding=1),
            nn.LayerNorm([256, 8, 8]),
            nn.GELU(),
            nn.Conv2d(256, config.hidden_size, 3, stride=2, padding=1),
            nn.LayerNorm([config.hidden_size, 4, 4]),
            nn.GELU(),
        )
        
        self.num_memory_tokens = 16
        self.memory_pos = nn.Parameter(torch.randn(1, self.num_memory_tokens, config.hidden_size) * 0.02)
    
    def forward(self, latent: torch.Tensor) -> torch.Tensor:
        B = latent.shape[0]
        x = self.cnn(latent)
        x = x.view(B, x.shape[1], -1).transpose(1, 2)
        x = x + self.memory_pos.expand(B, -1, -1)
        return x


class GcodeDecoderV3(nn.Module):
    """Large transformer decoder for gcode generation (v3)."""
    
    def __init__(self, config: GcodeDecoderConfigV3):
        super().__init__()
        self.config = config
        
        self.latent_proj = CNNLatentProjector(config)
        self.token_embed = nn.Embedding(config.vocab_size, config.hidden_size)
        self.pos_embed = nn.Embedding(config.max_seq_len, config.hidden_size)
        self.embed_drop = nn.Dropout(config.dropout)
        
        self.layers = nn.ModuleList([
            nn.TransformerDecoderLayer(
                d_model=config.hidden_size,
                nhead=config.num_heads,
                dim_feedforward=config.hidden_size * config.ffn_mult,
                dropout=config.dropout,
                activation='gelu',
                batch_first=True,
                norm_first=True,
            )
            for _ in range(config.num_layers)
        ])
        
        self.ln_f = nn.LayerNorm(config.hidden_size)
        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
        
    def forward(self, latent: torch.Tensor, input_ids: torch.Tensor) -> torch.Tensor:
        B, seq_len = input_ids.shape
        device = input_ids.device
        dtype = latent.dtype
        
        memory = self.latent_proj(latent)
        positions = torch.arange(seq_len, device=device)
        x = self.token_embed(input_ids) + self.pos_embed(positions)
        x = self.embed_drop(x)
        
        causal_mask = nn.Transformer.generate_square_subsequent_mask(seq_len, device=device, dtype=dtype)
        
        for layer in self.layers:
            x = layer(x, memory, tgt_mask=causal_mask)
        
        x = self.ln_f(x)
        return self.lm_head(x)


# ============================================================================
# V2 DECODER ARCHITECTURE (for backwards compatibility)
# ============================================================================

class GcodeDecoderConfigV2:
    def __init__(
        self,
        latent_channels: int = 4,
        latent_size: int = 64,
        hidden_size: int = 768,
        num_layers: int = 6,
        num_heads: int = 12,
        vocab_size: int = 32128,
        max_seq_len: int = 1024,
        dropout: float = 0.1,
    ):
        self.latent_channels = latent_channels
        self.latent_size = latent_size
        self.latent_dim = latent_channels * latent_size * latent_size
        self.hidden_size = hidden_size
        self.num_layers = num_layers
        self.num_heads = num_heads
        self.vocab_size = vocab_size
        self.max_seq_len = max_seq_len
        self.dropout = dropout


class GcodeDecoderV2(nn.Module):
    def __init__(self, config: GcodeDecoderConfigV2):
        super().__init__()
        self.config = config
        
        self.latent_proj = nn.Sequential(
            nn.Linear(config.latent_dim, config.hidden_size * 4),
            nn.GELU(),
            nn.Linear(config.hidden_size * 4, config.hidden_size * 16),
            nn.LayerNorm(config.hidden_size * 16),
        )
        
        self.token_embed = nn.Embedding(config.vocab_size, config.hidden_size)
        self.pos_embed = nn.Embedding(config.max_seq_len, config.hidden_size)
        
        self.layers = nn.ModuleList([
            nn.TransformerDecoderLayer(
                d_model=config.hidden_size,
                nhead=config.num_heads,
                dim_feedforward=config.hidden_size * 4,
                dropout=config.dropout,
                activation='gelu',
                batch_first=True,
                norm_first=True,
            )
            for _ in range(config.num_layers)
        ])
        
        self.ln_f = nn.LayerNorm(config.hidden_size)
        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
        self.lm_head.weight = self.token_embed.weight
        
    def forward(self, latent: torch.Tensor, input_ids: torch.Tensor) -> torch.Tensor:
        batch_size, seq_len = input_ids.shape
        device = input_ids.device
        dtype = latent.dtype
        
        latent_flat = latent.view(batch_size, -1)
        memory = self.latent_proj(latent_flat)
        memory = memory.view(batch_size, 16, self.config.hidden_size)
        
        positions = torch.arange(seq_len, device=device)
        x = self.token_embed(input_ids) + self.pos_embed(positions)
        
        causal_mask = nn.Transformer.generate_square_subsequent_mask(seq_len, device=device, dtype=dtype)
        
        for layer in self.layers:
            x = layer(x, memory, tgt_mask=causal_mask)
        
        x = self.ln_f(x)
        return self.lm_head(x)


# ============================================================================
# MODEL LOADING
# ============================================================================

def get_model():
    """Load and cache the SD-Gcode model."""
    global _model
    if _model is None:
        from diffusers import StableDiffusionPipeline
        from transformers import AutoTokenizer, PreTrainedTokenizerFast
        from huggingface_hub import hf_hub_download
        
        device = "cuda" if torch.cuda.is_available() else "cpu"
        dtype = torch.float16 if device == "cuda" else torch.float32
        
        print("Loading SD-Gcode model...")
        
        # Download config and weights
        config_path = hf_hub_download("twarner/dcode-sd-gcode", "config.json")
        weights_path = hf_hub_download("twarner/dcode-sd-gcode", "pytorch_model.bin")
        
        with open(config_path) as f:
            config = json.load(f)
        
        # Determine model version
        gcode_cfg = config.get("gcode_decoder", {})
        is_v3 = gcode_cfg.get("ffn_mult") is not None or gcode_cfg.get("hidden_size", 768) >= 1024
        
        print(f"Model version: {'v3' if is_v3 else 'v2'}")
        
        # Load SD pipeline
        sd_model_id = config.get("sd_model_id", "runwayml/stable-diffusion-v1-5")
        print(f"Loading SD from {sd_model_id}...")
        pipe = StableDiffusionPipeline.from_pretrained(
            sd_model_id,
            torch_dtype=dtype,
            safety_checker=None,
        ).to(device)
        
        # Build decoder based on version
        if is_v3:
            decoder_config = GcodeDecoderConfigV3(
                latent_channels=gcode_cfg.get("latent_channels", 4),
                latent_size=gcode_cfg.get("latent_size", 64),
                hidden_size=gcode_cfg.get("hidden_size", 1024),
                num_layers=gcode_cfg.get("num_layers", 12),
                num_heads=gcode_cfg.get("num_heads", 16),
                vocab_size=gcode_cfg.get("vocab_size", 8192),
                max_seq_len=gcode_cfg.get("max_seq_len", 2048),
                ffn_mult=gcode_cfg.get("ffn_mult", 4),
            )
            gcode_decoder = GcodeDecoderV3(decoder_config).to(device, dtype)
        else:
            decoder_config = GcodeDecoderConfigV2(
                latent_channels=gcode_cfg.get("latent_channels", 4),
                latent_size=gcode_cfg.get("latent_size", 64),
                hidden_size=gcode_cfg.get("hidden_size", 768),
                num_layers=gcode_cfg.get("num_layers", 6),
                num_heads=gcode_cfg.get("num_heads", 12),
                vocab_size=gcode_cfg.get("vocab_size", 32128),
                max_seq_len=gcode_cfg.get("max_seq_len", 1024),
            )
            gcode_decoder = GcodeDecoderV2(decoder_config).to(device, dtype)
        
        # Load weights
        print("Loading finetuned weights...")
        state_dict = torch.load(weights_path, map_location=device, weights_only=False)
        
        # Load SD components if present
        text_encoder_state = {k.replace("text_encoder.", ""): v for k, v in state_dict.items() 
                             if k.startswith("text_encoder.")}
        if text_encoder_state:
            pipe.text_encoder.load_state_dict(text_encoder_state, strict=False)
            print(f"Loaded {len(text_encoder_state)} text encoder weights")
        
        unet_state = {k.replace("unet.", ""): v for k, v in state_dict.items() 
                     if k.startswith("unet.")}
        if unet_state:
            pipe.unet.load_state_dict(unet_state, strict=False)
            print(f"Loaded {len(unet_state)} UNet weights")
        
        # Load decoder weights
        decoder_state = {k.replace("gcode_decoder.", ""): v for k, v in state_dict.items() 
                        if k.startswith("gcode_decoder.")}
        if decoder_state:
            try:
                gcode_decoder.load_state_dict(decoder_state, strict=True)
                print(f"Loaded {len(decoder_state)} decoder weights (strict)")
            except Exception as e:
                print(f"Strict load failed: {e}")
                gcode_decoder.load_state_dict(decoder_state, strict=False)
                print(f"Loaded {len(decoder_state)} decoder weights (non-strict)")
        
        gcode_decoder.eval()
        
        # Load gcode tokenizer
        try:
            # Try loading custom tokenizer
            tokenizer_path = hf_hub_download("twarner/dcode-sd-gcode", "gcode_tokenizer/tokenizer.json")
            gcode_tokenizer = PreTrainedTokenizerFast(tokenizer_file=tokenizer_path)
            print("Loaded custom gcode tokenizer")
        except Exception:
            # Fallback to T5 tokenizer
            gcode_tokenizer = AutoTokenizer.from_pretrained("google/flan-t5-base")
            print("Using fallback T5 tokenizer")
        
        _model = {
            "pipe": pipe,
            "gcode_decoder": gcode_decoder,
            "gcode_tokenizer": gcode_tokenizer,
            "device": device,
            "dtype": dtype,
            "num_inference_steps": config.get("num_inference_steps", 20),
            "is_v3": is_v3,
        }
        print("Model loaded!")
    
    return _model


# ============================================================================
# GCODE PROCESSING
# ============================================================================

def validate_gcode(gcode: str) -> str:
    """Clamp coordinates to machine bounds."""
    lines = []
    for line in gcode.split("\n"):
        corrected = line
        
        x_match = re.search(r"X([-\d.]+)", line, re.IGNORECASE)
        if x_match:
            try:
                x = float(x_match.group(1))
                x = max(BOUNDS["left"], min(BOUNDS["right"], x))
                corrected = re.sub(r"X[-\d.]+", f"X{x:.2f}", corrected, flags=re.IGNORECASE)
            except ValueError:
                pass

        y_match = re.search(r"Y([-\d.]+)", line, re.IGNORECASE)
        if y_match:
            try:
                y = float(y_match.group(1))
                y = max(BOUNDS["bottom"], min(BOUNDS["top"], y))
                corrected = re.sub(r"Y[-\d.]+", f"Y{y:.2f}", corrected, flags=re.IGNORECASE)
            except ValueError:
                pass

        lines.append(corrected)

    return "\n".join(lines)


def gcode_to_svg(gcode: str) -> str:
    """Convert gcode to SVG for visual preview."""
    paths = []
    current_path = []
    x, y = 0.0, 0.0
    pen_down = False

    # Split on newlines, newline tokens, or command boundaries
    lines = []
    # Replace newline tokens with actual newlines
    gcode = gcode.replace("<newline>", "\n")
    
    for line in gcode.replace(";", "\n;").split("\n"):
        line = line.strip()
        if not line:
            continue
        parts = re.split(r'(?=[GM]\d)', line)
        for part in parts:
            part = part.strip()
            if part and not part.startswith(";"):
                lines.append(part)
    
    for line in lines:
        if "M280" in line.upper():
            match = re.search(r"S(\d+)", line, re.IGNORECASE)
            if match:
                angle = int(match.group(1))
                was_down = pen_down
                pen_down = angle < 50
                if was_down and not pen_down and len(current_path) > 1:
                    paths.append(current_path[:])
                    current_path = []

        x_match = re.search(r"X([-\d.]+)", line, re.IGNORECASE)
        y_match = re.search(r"Y([-\d.]+)", line, re.IGNORECASE)
        
        if x_match:
            try:
                x = float(x_match.group(1))
            except ValueError:
                pass
        if y_match:
            try:
                y = float(y_match.group(1))
            except ValueError:
                pass

        if (x_match or y_match) and pen_down:
            current_path.append((x, y))

    if len(current_path) > 1:
        paths.append(current_path)

    w = BOUNDS["right"] - BOUNDS["left"]
    h = BOUNDS["top"] - BOUNDS["bottom"]
    padding = 20
    
    svg = f'''<svg xmlns="http://www.w3.org/2000/svg" 
                  viewBox="{BOUNDS["left"] - padding} {-BOUNDS["top"] - padding} {w + 2*padding} {h + 2*padding}" 
                  style="width: 100%; height: 480px; border: 1px solid var(--border, #e0e0e0); border-radius: 4px;">
        <style>
            @media (prefers-color-scheme: dark) {{
                .bg {{ fill: #2a2b30; }}
                .work {{ fill: #212226; stroke: #3a3b40; }}
                .stroke {{ stroke: #e8e8e8; }}
                .label {{ fill: #666; }}
            }}
            @media (prefers-color-scheme: light) {{
                .bg {{ fill: #fff; }}
                .work {{ fill: #fafafa; stroke: #ccc; }}
                .stroke {{ stroke: #1a1a1a; }}
                .label {{ fill: #999; }}
            }}
        </style>
        <rect class="bg" x="{BOUNDS["left"] - padding}" y="{-BOUNDS["top"] - padding}" width="{w + 2*padding}" height="{h + 2*padding}"/>
        <rect class="work" x="{BOUNDS["left"]}" y="{-BOUNDS["top"]}" width="{w}" height="{h}" stroke-width="1"/>
    '''

    for path in paths:
        if len(path) < 2:
            continue
        d = " ".join(f"{'M' if i == 0 else 'L'}{p[0]:.1f},{-p[1]:.1f}" for i, p in enumerate(path))
        svg += f'<path class="stroke" d="{d}" fill="none" stroke-width="1" stroke-linecap="round" stroke-linejoin="round"/>'

    total_points = sum(len(p) for p in paths)
    svg += f'''
        <text class="label" x="{BOUNDS["left"] + 8}" y="{-BOUNDS["top"] + 20}" font-family="monospace" font-size="12">
            {len(paths)} paths / {total_points} points
        </text>
    '''
    svg += "</svg>"
    return svg


# ============================================================================
# GENERATION
# ============================================================================

@spaces.GPU
def generate(prompt: str, temperature: float, max_tokens: int, num_steps: int, guidance: float):
    """Generate gcode from text prompt."""
    if not prompt or not prompt.strip():
        return "Enter a prompt to generate gcode", gcode_to_svg("")

    try:
        m = get_model()
        pipe = m["pipe"]
        gcode_decoder = m["gcode_decoder"]
        gcode_tokenizer = m["gcode_tokenizer"]
        device = m["device"]
        dtype = m["dtype"]
        is_v3 = m.get("is_v3", False)
        
        # Text -> Latent via SD diffusion
        with torch.no_grad():
            result = pipe(
                prompt,
                num_inference_steps=num_steps,
                guidance_scale=guidance,
                output_type="latent",
            )
            latent = result.images.to(dtype)
            print(f"Latent shape: {latent.shape}, dtype: {latent.dtype}")
        
        # Latent -> Gcode via trained decoder
        with torch.no_grad():
            batch_size = latent.shape[0]
            
            # Start token
            if is_v3:
                # V3 uses custom tokenizer with BOS
                start_id = gcode_tokenizer.bos_token_id or 0
            else:
                # V2 uses semicolon as start
                start_tokens = gcode_tokenizer.encode(";", add_special_tokens=False)
                start_id = start_tokens[0] if start_tokens else gcode_tokenizer.pad_token_id
            
            input_ids = torch.tensor([[start_id]], dtype=torch.long, device=device)
            
            max_gen = min(max_tokens, gcode_decoder.config.max_seq_len - 1)
            
            for step in range(max_gen):
                logits = gcode_decoder(latent, input_ids)
                next_logits = logits[:, -1, :] / temperature
                
                # Top-p sampling
                sorted_logits, sorted_indices = torch.sort(next_logits, descending=True)
                cumulative_probs = torch.cumsum(torch.softmax(sorted_logits, dim=-1), dim=-1)
                sorted_indices_to_remove = cumulative_probs > 0.9
                sorted_indices_to_remove[:, 1:] = sorted_indices_to_remove[:, :-1].clone()
                sorted_indices_to_remove[:, 0] = False
                
                for b in range(batch_size):
                    next_logits[b, sorted_indices[b, sorted_indices_to_remove[b]]] = float('-inf')
                
                probs = torch.softmax(next_logits, dim=-1)
                next_token = torch.multinomial(probs, num_samples=1)
                input_ids = torch.cat([input_ids, next_token], dim=1)
                
                # Check EOS
                if next_token.item() == gcode_tokenizer.eos_token_id:
                    break
            
            print(f"Generated {input_ids.shape[1]} tokens")
            gcode = gcode_tokenizer.decode(input_ids[0], skip_special_tokens=True)
            
            # Post-process for v3: restore newlines
            if is_v3:
                gcode = gcode.replace("<newline>", "\n")
            
            print(f"Decoded gcode length: {len(gcode)} chars")
        
        gcode = validate_gcode(gcode)
        line_count = len([l for l in gcode.split("\n") if l.strip()])
        svg = gcode_to_svg(gcode)
        
        header = f"; dcode output\n; prompt: {prompt}\n; {line_count} commands\n\n"
        return header + gcode, svg
        
    except Exception as e:
        import traceback
        traceback.print_exc()
        return f"; Error: {e}", gcode_to_svg("")


# ============================================================================
# UI
# ============================================================================

css = """
@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500&display=swap');

:root {
    --bg: #ffffff;
    --bg-secondary: #fafafa;
    --text: #1a1a1a;
    --text-secondary: #666;
    --border: #e0e0e0;
    --btn-bg: #f0f0f0;
    --btn-hover: #e0e0e0;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #212226;
        --bg-secondary: #2a2b30;
        --text: #e8e8e8;
        --text-secondary: #999;
        --border: #3a3b40;
        --btn-bg: #3a3b40;
        --btn-hover: #4a4b50;
    }
}

* {
    font-family: 'IBM Plex Mono', monospace !important;
}

body, .gradio-container {
    background: var(--bg) !important;
    color: var(--text) !important;
}

.gradio-container {
    max-width: 900px !important;
    margin: auto;
}

.gr-button {
    background: var(--btn-bg) !important;
    border: 1px solid var(--border) !important;
    color: var(--text) !important;
    font-weight: 500 !important;
}

.gr-button:hover {
    background: var(--btn-hover) !important;
}

.gr-examples {
    margin-top: 8px !important;
}

footer {
    display: none !important;
}

h1, h2, h3, p, span, label {
    color: var(--text) !important;
}

.gr-box, .gr-panel, .gr-form {
    background: var(--bg-secondary) !important;
    border: 1px solid var(--border) !important;
    border-radius: 4px !important;
}

input, textarea {
    background: var(--bg) !important;
    color: var(--text) !important;
    border: 1px solid var(--border) !important;
    border-radius: 4px !important;
}

.gr-accordion {
    background: var(--bg-secondary) !important;
    border: 1px solid var(--border) !important;
}

a {
    color: var(--text-secondary) !important;
}

a:hover {
    color: var(--text) !important;
}
"""

with gr.Blocks(css=css, theme=gr.themes.Base()) as demo:
    gr.Markdown("# dcode")
    gr.Markdown("text → polargraph gcode via stable diffusion")
    
    with gr.Row():
        with gr.Column(scale=1):
            prompt = gr.Textbox(
                label="prompt", 
                placeholder="describe what to draw...",
                lines=2,
                show_label=True,
            )
            
            with gr.Accordion("settings", open=False):
                temperature = gr.Slider(0.5, 1.5, value=0.8, label="temperature", step=0.1)
                max_tokens = gr.Slider(256, 2048, value=1024, step=256, label="max tokens")
                num_steps = gr.Slider(10, 50, value=20, step=5, label="diffusion steps")
                guidance = gr.Slider(1.0, 15.0, value=7.5, step=0.5, label="guidance")
            
            generate_btn = gr.Button("generate", variant="secondary")
            
            gr.Examples(
                examples=[
                    ["a line drawing of a horse"],
                    ["portrait sketch"],
                    ["geometric shapes"],
                ],
                inputs=prompt,
                label=None,
                examples_per_page=3,
            )
        
        with gr.Column(scale=2):
            preview = gr.HTML(value=gcode_to_svg(""))
    
    with gr.Accordion("gcode", open=False):
        gcode_output = gr.Code(label=None, language=None, lines=12)
    
    gr.Markdown("---")
    gr.Markdown("machine: 841×1189mm / pen servo 40-90° / [github](https://github.com/Twarner491/dcode) / [model](https://huggingface.co/twarner/dcode-sd-gcode) / mit")
    
    generate_btn.click(generate, [prompt, temperature, max_tokens, num_steps, guidance], [gcode_output, preview])
    prompt.submit(generate, [prompt, temperature, max_tokens, num_steps, guidance], [gcode_output, preview])

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