import gradio as gr
from threading import Thread
import time
from PIL import Image
import torch
import spaces
import cv2
import numpy as np
from transformers import (
     AutoProcessor, 
     AutoModelForVision2Seq, 
     TextIteratorStreamer
)
# Helper function to return a progress bar HTML snippet.
def progress_bar_html(label: str) -> str:
    return f'''
<div style="display: flex; align-items: center;">
    <span style="margin-right: 10px; font-size: 14px;">{label}</span>
    <div style="width: 110px; height: 5px; background-color: #FFB6C1; border-radius: 2px; overflow: hidden;">
        <div style="width: 100%; height: 100%; background-color: #FF69B4; animation: loading 1.5s linear infinite;"></div>
    </div>
</div>
<style>
@keyframes loading {{
    0% {{ transform: translateX(-100%); }}
    100% {{ transform: translateX(100%); }}
}}
</style>
    '''

#adding examples
examples=[
        [{"text": "Explain the Image", "files": ["examples/3.jpg"]}],
        [{"text": "Transcription of the letter", "files": ["examples/222.png"]}],
        [{"text": "@video-infer Explain the content of the Advertisement", "files": ["examples/videoplayback.mp4"]}],
        [{"text": "@video-infer Explain the content of the video in detail", "files": ["examples/breakfast.mp4"]}],
        [{"text": "@video-infer Describe the video", "files": ["examples/Missing.mp4"]}],
        [{"text": "@video-infer Explain what is happening in this video ?", "files": ["examples/oreo.mp4"]}],
        [{"text": "@video-infer Summarize the events in this video", "files": ["examples/sky.mp4"]}],
        [{"text": "@video-infer What is in the video ?", "files": ["examples/redlight.mp4"]}],
]

# Helper: Downsample video to extract a fixed number of frames.
def downsample_video(video_path, num_frames=10):
    cap = cv2.VideoCapture(video_path)
    total_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
    fps = cap.get(cv2.CAP_PROP_FPS)
    # Calculate evenly spaced frame indices.
    frame_indices = np.linspace(0, total_frames - 1, num_frames, dtype=int)
    frames = []
    for idx in frame_indices:
        cap.set(cv2.CAP_PROP_POS_FRAMES, idx)
        ret, frame = cap.read()
        if ret:
            # Convert BGR to RGB and then to a PIL image.
            frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            frame = Image.fromarray(frame)
            frames.append(frame)
    cap.release()
    return frames

# Load processor and model.
processor = AutoProcessor.from_pretrained("HuggingFaceTB/SmolVLM-Instruct")
model = AutoModelForVision2Seq.from_pretrained(
    "HuggingFaceTB/SmolVLM-Instruct", 
    torch_dtype=torch.bfloat16,
).to("cuda")

@spaces.GPU
def model_inference(
    input_dict, history, decoding_strategy, temperature, max_new_tokens,
    repetition_penalty, top_p
): 
    text = input_dict["text"]
    
    # --- Video Inference Branch ---
    if text.lower().startswith("@video-infer"):
        # Remove the command prefix to get the prompt.
        prompt_text = text[len("@video-infer"):].strip()
        if not input_dict["files"]:
            yield "Error: Please provide a video file for @video-infer."
            return
        # Assume the first file is a video.
        video_file = input_dict["files"][0]
        frames = downsample_video(video_file)
        if not frames:
            yield "Error: Could not extract frames from the video."
            return
        # Build a chat content: include the user prompt and then each frame labeled.
        content = [{"type": "text", "text": prompt_text}]
        for idx, frame in enumerate(frames):
            content.append({"type": "text", "text": f"Frame {idx+1}:"})
            content.append({"type": "image", "image": frame})
        resulting_messages = [{
            "role": "user",
            "content": content
        }]
        prompt = processor.apply_chat_template(resulting_messages, add_generation_prompt=True)
        # Process the extracted frames as images.
        inputs = processor(text=prompt, images=[frames], return_tensors="pt")
        inputs = {k: v.to("cuda") for k, v in inputs.items()}
        
        # Setup generation parameters.
        generation_args = {
            "max_new_tokens": max_new_tokens,
            "repetition_penalty": repetition_penalty,
        }
        assert decoding_strategy in ["Greedy", "Top P Sampling"]
        if decoding_strategy == "Greedy":
            generation_args["do_sample"] = False
        elif decoding_strategy == "Top P Sampling":
            generation_args["temperature"] = temperature
            generation_args["do_sample"] = True
            generation_args["top_p"] = top_p
        
        generation_args.update(inputs)
        
        streamer = TextIteratorStreamer(processor, skip_prompt=True, skip_special_tokens=True)
        generation_args = dict(inputs, streamer=streamer, max_new_tokens=max_new_tokens)
        buffer = ""
        thread = Thread(target=model.generate, kwargs=generation_args)
        thread.start()
        yield progress_bar_html("Processing Video with SmolVLM")
        for new_text in streamer:
            buffer += new_text
            time.sleep(0.01)
            yield buffer
        return

    # --- Default Image Inference Branch ---
    # Process input images if provided.
    if len(input_dict["files"]) > 1:
        images = [Image.open(image).convert("RGB") for image in input_dict["files"]]
    elif len(input_dict["files"]) == 1:
        images = [Image.open(input_dict["files"][0]).convert("RGB")]
    else:
        images = []
    
    # Validate input.
    if text == "" and not images:
        gr.Error("Please input a query and optionally image(s).")
    if text == "" and images:
        gr.Error("Please input a text query along with the image(s).")
    
    resulting_messages = [{
        "role": "user",
        "content": [{"type": "image"} for _ in range(len(images))] + [
            {"type": "text", "text": text}
        ]
    }]
    prompt = processor.apply_chat_template(resulting_messages, add_generation_prompt=True)
    inputs = processor(text=prompt, images=[images], return_tensors="pt")
    inputs = {k: v.to("cuda") for k, v in inputs.items()}
    
    generation_args = {
        "max_new_tokens": max_new_tokens,
        "repetition_penalty": repetition_penalty,
    }
    assert decoding_strategy in ["Greedy", "Top P Sampling"]
    if decoding_strategy == "Greedy":
        generation_args["do_sample"] = False
    elif decoding_strategy == "Top P Sampling":
        generation_args["temperature"] = temperature
        generation_args["do_sample"] = True
        generation_args["top_p"] = top_p

    generation_args.update(inputs)
    
    streamer = TextIteratorStreamer(processor, skip_prompt=True, skip_special_tokens=True)
    generation_args = dict(inputs, streamer=streamer, max_new_tokens=max_new_tokens)
    buffer = ""
    thread = Thread(target=model.generate, kwargs=generation_args)
    thread.start()
    yield progress_bar_html("Processing Video with SmolVLM")
    for new_text in streamer:
        buffer += new_text
        time.sleep(0.01)
        yield buffer

# Gradio ChatInterface: Allow both image and video file types.
demo = gr.ChatInterface(
    fn=model_inference,
    description="# **SmolVLM Video Infer `@video-infer for video understanding`**",
    examples=examples,
    textbox=gr.MultimodalTextbox(
        label="Query Input", 
        file_types=["image", "video"], 
        file_count="multiple"
    ),
    stop_btn="Stop Generation",
    multimodal=True,
    additional_inputs=[
        gr.Radio(
            ["Top P Sampling", "Greedy"],
            value="Greedy",
            label="Decoding strategy",
            info="Higher values is equivalent to sampling more low-probability tokens.",
        ),
        gr.Slider(
            minimum=0.0,
            maximum=5.0,
            value=0.4,
            step=0.1,
            interactive=True,
            label="Sampling temperature",
            info="Higher values will produce more diverse outputs.",
        ),
        gr.Slider(
            minimum=8,
            maximum=1024,
            value=512,
            step=1,
            interactive=True,
            label="Maximum number of new tokens to generate",
        ),
        gr.Slider(
            minimum=0.01,
            maximum=5.0,
            value=1.2,
            step=0.01,
            interactive=True,
            label="Repetition penalty",
            info="1.0 is equivalent to no penalty",
        ),
        gr.Slider(
            minimum=0.01,
            maximum=0.99,
            value=0.8,
            step=0.01,
            interactive=True,
            label="Top P",
            info="Higher values is equivalent to sampling more low-probability tokens.",
        )
    ],
    cache_examples=False
)

demo.launch(debug=True)