"""
🎯 YOLO Trainer & Detector
Train YOLOv8 on a custom dataset and run inference — all from a Gradio UI.
"""

import os
import io
import time
import queue
import threading
import zipfile
import yaml
import cv2
import numpy as np
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
from PIL import Image as PILImage
from pathlib import Path

import gradio as gr
from ultralytics import YOLO
from huggingface_hub import hf_hub_download

# ═══════════════════════════════════════════════════════════════
# Constants
# ═══════════════════════════════════════════════════════════════
DATASET_REPO = "dharshanzeb/yolo-detection-dataset"
DATASET_DIR = "/tmp/yolo_dataset"
RUNS_DIR = "/tmp/yolo_runs"
BEST_MODEL_PATH = os.path.join(RUNS_DIR, "gradio_train", "weights", "best.pt")
LAST_MODEL_PATH = os.path.join(RUNS_DIR, "gradio_train", "weights", "last.pt")

CLASS_NAMES = ["car", "person", "dog", "cat", "bicycle"]

# Global state
trained_model_path = None
is_training = False


# ═══════════════════════════════════════════════════════════════
# Dataset download & preparation
# ═══════════════════════════════════════════════════════════════
def download_dataset():
    """Download YOLO dataset from HF Hub and prepare data.yaml."""
    if os.path.exists(os.path.join(DATASET_DIR, "images", "train")):
        yaml_path = os.path.join(DATASET_DIR, "data.yaml")
        if os.path.exists(yaml_path):
            return yaml_path, "✅ Dataset already downloaded."

    log = "📥 Downloading dataset from HF Hub...\n"

    os.makedirs(DATASET_DIR, exist_ok=True)
    for split in ["train", "val", "test"]:
        log += f"   Downloading {split}.zip...\n"
        zip_path = hf_hub_download(
            repo_id=DATASET_REPO,
            filename=f"yolo_format/{split}.zip",
            repo_type="dataset",
        )
        with zipfile.ZipFile(zip_path) as zf:
            zf.extractall(DATASET_DIR)

    # Download and patch data.yaml
    yaml_remote = hf_hub_download(
        repo_id=DATASET_REPO,
        filename="yolo_format/data.yaml",
        repo_type="dataset",
    )
    with open(yaml_remote) as f:
        cfg = yaml.safe_load(f)
    cfg["path"] = DATASET_DIR
    local_yaml = os.path.join(DATASET_DIR, "data.yaml")
    with open(local_yaml, "w") as f:
        yaml.dump(cfg, f)

    # Count images
    n_train = len(list(Path(DATASET_DIR, "images", "train").glob("*.jpg")))
    n_val = len(list(Path(DATASET_DIR, "images", "val").glob("*.jpg")))
    n_test = len(list(Path(DATASET_DIR, "images", "test").glob("*.jpg")))
    log += f"\n✅ Dataset ready!\n"
    log += f"   Train: {n_train} images\n"
    log += f"   Val:   {n_val} images\n"
    log += f"   Test:  {n_test} images\n"
    log += f"   Classes: {CLASS_NAMES}\n"

    return local_yaml, log


# ═══════════════════════════════════════════════════════════════
# Metrics chart
# ═══════════════════════════════════════════════════════════════
def make_metrics_chart(history):
    """Create a loss + mAP chart from training history."""
    if not history:
        return None

    epochs = [h["epoch"] for h in history]

    fig, axes = plt.subplots(1, 2, figsize=(14, 5))
    fig.patch.set_facecolor("#1a1a2e")

    # ── Loss subplot ──
    ax1 = axes[0]
    ax1.set_facecolor("#16213e")
    loss_keys = list(history[0].get("loss", {}).keys())
    colors_loss = ["#e94560", "#f5a623", "#50fa7b"]
    for i, k in enumerate(loss_keys):
        vals = [h["loss"].get(k, 0) for h in history]
        label = k.split("/")[-1] if "/" in k else k
        color = colors_loss[i % len(colors_loss)]
        ax1.plot(epochs, vals, marker="o", markersize=4, label=label,
                 color=color, linewidth=2)
    ax1.set_title("Training Loss", color="white", fontsize=14, fontweight="bold")
    ax1.set_xlabel("Epoch", color="white")
    ax1.set_ylabel("Loss", color="white")
    ax1.legend(facecolor="#16213e", edgecolor="white", labelcolor="white")
    ax1.tick_params(colors="white")
    ax1.grid(True, alpha=0.2, color="white")
    for spine in ax1.spines.values():
        spine.set_color("white")

    # ── mAP subplot ──
    ax2 = axes[1]
    ax2.set_facecolor("#16213e")
    map_keys = [
        ("metrics/mAP50(B)", "mAP@50", "#00d2ff"),
        ("metrics/mAP50-95(B)", "mAP@50-95", "#7b2ff7"),
    ]
    for key, label, color in map_keys:
        vals = [h["metrics"].get(key, 0) for h in history]
        if any(v > 0 for v in vals):
            ax2.plot(epochs, vals, marker="s", markersize=4, label=label,
                     color=color, linewidth=2)
    ax2.set_title("Validation mAP", color="white", fontsize=14, fontweight="bold")
    ax2.set_xlabel("Epoch", color="white")
    ax2.set_ylabel("mAP", color="white")
    ax2.set_ylim(0, 1)
    ax2.legend(facecolor="#16213e", edgecolor="white", labelcolor="white")
    ax2.tick_params(colors="white")
    ax2.grid(True, alpha=0.2, color="white")
    for spine in ax2.spines.values():
        spine.set_color("white")

    plt.tight_layout(pad=2)
    buf = io.BytesIO()
    plt.savefig(buf, format="png", dpi=120, bbox_inches="tight",
                facecolor=fig.get_facecolor())
    buf.seek(0)
    chart = np.array(PILImage.open(buf).copy())
    plt.close(fig)
    return chart


# ═══════════════════════════════════════════════════════════════
# Training function (generator for streaming logs)
# ═══════════════════════════════════════════════════════════════
def train_yolo(model_size, epochs, batch_size, learning_rate, img_size):
    """
    Generator function: trains YOLO and yields (log_text, metrics_chart, status)
    after each epoch.
    """
    global trained_model_path, is_training

    if is_training:
        yield "⚠️ Training already in progress. Please wait.", None, "⚠️ Busy"
        return

    is_training = True
    log_queue_local = queue.Queue()
    history = []
    accumulated_log = ""
    train_exception = [None]

    try:
        # Step 1: Download dataset
        yield "📥 Preparing dataset...", None, "📥 Downloading..."
        data_yaml, dl_log = download_dataset()
        accumulated_log += dl_log + "\n"
        yield accumulated_log, None, "📥 Dataset ready"

        # Step 2: Load model
        model_variant = f"yolov8{model_size}.pt"
        accumulated_log += f"🔄 Loading {model_variant}...\n"
        yield accumulated_log, None, f"🔄 Loading {model_variant}"

        model = YOLO(model_variant)

        # Step 3: Attach callback
        def on_fit_epoch_end(trainer):
            try:
                loss_dict = {}
                if trainer.tloss is not None:
                    loss_dict = trainer.label_loss_items(trainer.tloss)

                entry = {
                    "epoch": trainer.epoch + 1,
                    "epochs": trainer.epochs,
                    "metrics": dict(trainer.metrics) if trainer.metrics else {},
                    "fitness": float(trainer.fitness) if trainer.fitness else 0.0,
                    "loss": loss_dict,
                }
                log_queue_local.put(entry)
            except Exception as e:
                log_queue_local.put({"error": str(e)})

        model.add_callback("on_fit_epoch_end", on_fit_epoch_end)

        # Step 4: Run training in background thread
        def run_training():
            try:
                device = 0 if __import__("torch").cuda.is_available() else "cpu"
                model.train(
                    data=data_yaml,
                    epochs=int(epochs),
                    batch=int(batch_size),
                    lr0=float(learning_rate),
                    imgsz=int(img_size),
                    device=device,
                    workers=0,
                    project=RUNS_DIR,
                    name="gradio_train",
                    exist_ok=True,
                    pretrained=True,
                    mosaic=1.0,
                    mixup=0.1,
                    patience=50,
                    verbose=False,
                )
            except Exception as e:
                train_exception[0] = e
            finally:
                log_queue_local.put(None)  # sentinel

        accumulated_log += f"\n🚀 Starting training: {model_variant} | {int(epochs)} epochs | batch={int(batch_size)} | lr={learning_rate}\n"
        accumulated_log += f"{'─' * 60}\n"
        yield accumulated_log, None, "🚀 Training started..."

        t = threading.Thread(target=run_training, daemon=True)
        t.start()

        # Step 5: Stream logs from queue
        while True:
            try:
                item = log_queue_local.get(timeout=120)
            except queue.Empty:
                accumulated_log += "⏳ Waiting for update...\n"
                yield accumulated_log, make_metrics_chart(history), "⏳ Waiting..."
                continue

            if item is None:
                break

            if "error" in item:
                accumulated_log += f"⚠️ Callback error: {item['error']}\n"
                yield accumulated_log, make_metrics_chart(history), "⚠️ Error"
                continue

            history.append(item)
            e, E = item["epoch"], item["epochs"]

            # Format loss
            loss_parts = []
            for k, v in item["loss"].items():
                name = k.split("/")[-1] if "/" in k else k
                loss_parts.append(f"{name}={v:.4f}")
            loss_str = " | ".join(loss_parts) if loss_parts else "N/A"

            # Format mAP
            map50 = item["metrics"].get("metrics/mAP50(B)", 0)
            map50_95 = item["metrics"].get("metrics/mAP50-95(B)", 0)

            line = f"📈 Epoch {e:>3d}/{E} | {loss_str} | mAP50={map50:.4f} | mAP50-95={map50_95:.4f}\n"
            accumulated_log += line

            chart = make_metrics_chart(history)
            status = f"🏋️ Epoch {e}/{E} | mAP50={map50:.4f}"
            yield accumulated_log, chart, status

        t.join(timeout=10)

        # Step 6: Check results
        if train_exception[0]:
            accumulated_log += f"\n❌ Training error: {train_exception[0]}\n"
            yield accumulated_log, make_metrics_chart(history), "❌ Failed"
            return

        # Find best model
        if os.path.exists(BEST_MODEL_PATH):
            trained_model_path = BEST_MODEL_PATH
        elif os.path.exists(LAST_MODEL_PATH):
            trained_model_path = LAST_MODEL_PATH

        accumulated_log += f"\n{'═' * 60}\n"
        accumulated_log += f"🎉 TRAINING COMPLETE!\n"
        accumulated_log += f"{'═' * 60}\n"
        if trained_model_path:
            accumulated_log += f"📁 Model saved: {trained_model_path}\n"
            accumulated_log += f"👉 Switch to the Inference tab to test your model!\n"
        else:
            accumulated_log += f"⚠️ No model file found after training.\n"

        if history:
            final_map = history[-1]["metrics"].get("metrics/mAP50(B)", 0)
            accumulated_log += f"\n📊 Final mAP@50: {final_map:.4f}\n"

        chart = make_metrics_chart(history)
        yield accumulated_log, chart, "✅ Training complete!"

    except Exception as e:
        accumulated_log += f"\n❌ Error: {str(e)}\n"
        yield accumulated_log, make_metrics_chart(history) if history else None, "❌ Error"
    finally:
        is_training = False


# ═══════════════════════════════════════════════════════════════
# Inference function
# ═══════════════════════════════════════════════════════════════
def run_inference(image, conf_threshold, use_pretrained):
    """Run YOLO detection on an uploaded image."""
    if image is None:
        gr.Warning("Please upload an image first!")
        return None, "⚠️ No image uploaded"

    # Select model
    if use_pretrained:
        model_path = "yolov8n.pt"
        model_label = "YOLOv8n (COCO pretrained)"
    else:
        if trained_model_path and os.path.exists(trained_model_path):
            model_path = trained_model_path
            model_label = f"Custom trained ({os.path.basename(trained_model_path)})"
        else:
            gr.Warning("No trained model found! Train first or use pretrained COCO model.")
            return None, "⚠️ No trained model. Train first or check 'Use Pretrained'."

    try:
        device = 0 if __import__("torch").cuda.is_available() else "cpu"
        model = YOLO(model_path)
        results = model.predict(
            source=image,
            conf=float(conf_threshold),
            iou=0.45,
            device=device,
            verbose=False,
        )
        result = results[0]

        # Draw bounding boxes
        plotted_bgr = result.plot(conf=True, labels=True, line_width=2)
        plotted_rgb = cv2.cvtColor(plotted_bgr, cv2.COLOR_BGR2RGB)

        # Build detection summary
        n_detections = len(result.boxes)
        if n_detections == 0:
            summary = f"🔍 **{model_label}**\n\nNo objects detected (conf > {conf_threshold})"
        else:
            lines = [f"🔍 **{model_label}** — Found **{n_detections}** objects:\n"]
            lines.append("| # | Class | Confidence | Bbox (x1,y1,x2,y2) |")
            lines.append("|---|-------|-----------|---------------------|")
            for i, box in enumerate(result.boxes):
                cls_id = int(box.cls[0].item())
                cls_name = result.names[cls_id]
                conf = box.conf[0].item()
                coords = [round(v, 1) for v in box.xyxy[0].tolist()]
                lines.append(f"| {i+1} | **{cls_name}** | {conf:.2f} | {coords} |")
            summary = "\n".join(lines)

        return plotted_rgb, summary

    except Exception as e:
        return None, f"❌ Error: {str(e)}"


# ═══════════════════════════════════════════════════════════════
# Sample images from dataset for inference demo
# ═══════════════════════════════════════════════════════════════
def load_sample_image():
    """Load a random sample from the test set."""
    test_dir = Path(DATASET_DIR) / "images" / "test"
    if not test_dir.exists():
        # Download dataset first
        download_dataset()

    if test_dir.exists():
        images = list(test_dir.glob("*.jpg"))
        if images:
            import random
            img_path = random.choice(images)
            return np.array(PILImage.open(img_path))
    return None


# ═══════════════════════════════════════════════════════════════
# Build Gradio UI
# ═══════════════════════════════════════════════════════════════
css = """
.gradio-container { max-width: 1100px !important; margin: 0 auto !important; }
.train-log { font-family: 'Courier New', monospace !important; font-size: 13px !important; }
"""

with gr.Blocks(css=css, title="🎯 YOLO Trainer & Detector", theme=gr.themes.Soft()) as demo:

    gr.Markdown("""
    # 🎯 YOLO Trainer & Detector
    **Train** a YOLOv8 model on the [yolo-detection-dataset](https://huggingface.co/datasets/dharshanzeb/yolo-detection-dataset)
    and **run inference** on any image — all from this UI.
    """)

    with gr.Tabs():
        # ══════════════════════════════════════════════════════
        # TAB 1: TRAINING
        # ══════════════════════════════════════════════════════
        with gr.Tab("🏋️ Train"):
            with gr.Row():
                # Left column: controls
                with gr.Column(scale=1, min_width=280):
                    gr.Markdown("### ⚙️ Training Configuration")

                    model_size = gr.Dropdown(
                        choices=[
                            ("YOLOv8 Nano (fastest)", "n"),
                            ("YOLOv8 Small", "s"),
                            ("YOLOv8 Medium", "m"),
                        ],
                        value="n",
                        label="Model Size",
                    )
                    epochs = gr.Slider(
                        minimum=1, maximum=100, value=20, step=1,
                        label="Epochs",
                    )
                    batch_size = gr.Slider(
                        minimum=4, maximum=64, value=16, step=4,
                        label="Batch Size",
                    )
                    learning_rate = gr.Slider(
                        minimum=0.0001, maximum=0.1, value=0.01, step=0.0001,
                        label="Learning Rate",
                    )
                    img_size = gr.Dropdown(
                        choices=[320, 416, 512, 640],
                        value=640,
                        label="Image Size",
                    )

                    train_btn = gr.Button(
                        "🚀 Start Training", variant="primary", size="lg"
                    )

                    train_status = gr.Markdown("*Ready to train*")

                    gr.Markdown("""
                    ---
                    ### 📋 Dataset Info
                    - **5 classes**: car, person, dog, cat, bicycle
                    - **500** train / **100** val / **50** test images
                    - **640×640** resolution
                    - 15% hard negatives included
                    """)

                # Right column: logs + chart
                with gr.Column(scale=2):
                    gr.Markdown("### 📊 Training Progress")
                    metrics_chart = gr.Image(
                        label="Loss & mAP Curves",
                        interactive=False,
                        height=320,
                    )
                    train_log = gr.Textbox(
                        label="Training Log",
                        lines=18,
                        max_lines=30,
                        interactive=False,
                        autoscroll=True,
                        elem_classes=["train-log"],
                    )

            # Wire training button
            train_btn.click(
                fn=train_yolo,
                inputs=[model_size, epochs, batch_size, learning_rate, img_size],
                outputs=[train_log, metrics_chart, train_status],
            )

        # ══════════════════════════════════════════════════════
        # TAB 2: INFERENCE
        # ══════════════════════════════════════════════════════
        with gr.Tab("🔍 Detect"):
            gr.Markdown("### Upload an image to detect objects")

            with gr.Row():
                # Left: input
                with gr.Column(scale=1):
                    input_image = gr.Image(
                        label="📤 Upload Image",
                        type="numpy",
                        sources=["upload", "clipboard"],
                        height=400,
                    )

                    with gr.Row():
                        conf_threshold = gr.Slider(
                            minimum=0.05, maximum=0.95, value=0.25, step=0.05,
                            label="Confidence Threshold",
                        )
                    with gr.Row():
                        use_pretrained = gr.Checkbox(
                            value=False,
                            label="Use Pretrained COCO Model (YOLOv8n)",
                            info="Check this if you haven't trained yet",
                        )
                    with gr.Row():
                        detect_btn = gr.Button(
                            "🔍 Detect Objects", variant="primary", size="lg"
                        )
                        sample_btn = gr.Button(
                            "🎲 Load Sample", variant="secondary", size="lg"
                        )

                # Right: output
                with gr.Column(scale=1):
                    output_image = gr.Image(
                        label="📸 Detection Result",
                        type="numpy",
                        interactive=False,
                        height=400,
                    )
                    detection_summary = gr.Markdown("*Upload an image and click Detect*")

            # Wire inference
            detect_btn.click(
                fn=run_inference,
                inputs=[input_image, conf_threshold, use_pretrained],
                outputs=[output_image, detection_summary],
            )

            sample_btn.click(
                fn=load_sample_image,
                outputs=[input_image],
            )

        # ══════════════════════════════════════════════════════
        # TAB 3: ABOUT
        # ══════════════════════════════════════════════════════
        with gr.Tab("ℹ️ About"):
            gr.Markdown("""
            ## How It Works

            ### 🏋️ Training
            1. The dataset ([dharshanzeb/yolo-detection-dataset](https://huggingface.co/datasets/dharshanzeb/yolo-detection-dataset))
               is auto-downloaded from the HF Hub
            2. YOLOv8 is initialized with COCO-pretrained weights (transfer learning)
            3. Training runs with your configured hyperparameters
            4. Real-time metrics (loss + mAP) are displayed after each epoch
            5. The best model (by mAP) is saved automatically

            ### 🔍 Inference
            - **Custom model**: Uses the model you just trained
            - **Pretrained COCO**: Uses YOLOv8n trained on 80 COCO classes (good for real photos)

            ### 🎯 Dataset Classes
            | ID | Class | Description |
            |---|---|---|
            | 0 | Car | Red car shapes with windows & wheels |
            | 1 | Person | Blue stick figures |
            | 2 | Dog | Brown dog shapes |
            | 3 | Cat | Orange cat shapes with ears |
            | 4 | Bicycle | Green bicycles with wheels |

            ### 💡 Tips
            - **First time?** Start with `YOLOv8 Nano` + `20 epochs` — trains in ~5 min on GPU
            - **Better accuracy?** Try `YOLOv8 Small` + `50 epochs` + `lr=0.01`
            - **No GPU?** Training works on CPU too (just slower). Use pretrained COCO for instant inference.
            - **Low mAP?** Increase epochs or try a larger model size

            ### 🔗 Links
            - [Dataset](https://huggingface.co/datasets/dharshanzeb/yolo-detection-dataset)
            - [Ultralytics YOLOv8](https://docs.ultralytics.com/)
            - [Gradio](https://gradio.app/)
            """)


if __name__ == "__main__":
    demo.queue(max_size=5).launch()