from shiny import App, Inputs, Outputs, Session, reactive, render, ui
from shiny.types import FileInfo, ImgData
import asyncio
import concurrent.futures

import backend

import numpy as np
from PIL import Image, ImageDraw
from pathlib import Path
import tempfile


def draw_layer_on_image(im: Image) -> Image:
    """Draws something on top of an image."""
    # Attempting to use thresholds.
    threshold: int = 1
    output_im = np.array(im)
    # return Image.fromarray(output_im)

    # The image drawing code.
    draw = ImageDraw.Draw(im)
    draw.line((0, 0) + im.size, fill=128, width=5)
    draw.line((0, im.size[1], im.size[0], 0), fill=128)

    return im


# UI:
# TITLE ELEMENT, centered
# input, centered.
# table in middle. Upload, displays image on the left.
# arrow in the middle, mask on the right.
card_height = '700px'
app_ui = ui.page_fixed(
    ui.input_file("file1", "Upload a sidewalk.", accept=[".jpg", ".png", ".jpeg"], multiple=False),
    ui.layout_columns(  
        ui.card(  
            ui.card_header("Uploaded Image"),
            ui.output_image("show_image"),
            height=card_height
        ),  
        ui.card(  
            ui.card_header("Image Mask"),
            # ui.input_task_button("mask_btn", "Process mask"),
            ui.output_image("samwalk"),
            height=card_height
        ),  
    )
)

def strip_alpha(image: Image) -> Image:
    # Create a white background
    background = Image.new('RGBA', image.size, (255, 255, 255, 255))
    composite = Image.alpha_composite(background, image)
    rgb_image = composite.convert('RGB')
    return rgb_image

def server(input: Inputs, output: Outputs, session: Session):
    uploaded_img = None

    @reactive.calc
    def parsed_file():
        file: list[FileInfo] | None = input.file1()
        if file is None:
            return
        return file[0]

    @render.image
    def show_image():
        uploaded_img = parsed_file()
        if uploaded_img is None:
            return
        uploaded_src = uploaded_img['datapath']
        img: ImgData = {"src": str(uploaded_src), "width": "500px"}
        return img
 
    # @reactive.event(input.mask_btn)
    @render.image
    def samwalk():
        uploaded_file = parsed_file()
        if uploaded_file is None:
            return
        uploaded_src = uploaded_file['datapath']
        uploaded_img = Image.open(uploaded_src)
        if uploaded_img.mode == 'RGBA':
            uploaded_img = strip_alpha(uploaded_img)
        dirpath = tempfile.mkdtemp()

        # output_img = async_process_image(uploaded_img)
        # while output_img is None:
        #     pass
        # output_img = output_img.result()
        #     # return {"src": str("waiting.gif"), "width": "500px"}
        output_img = backend.process_image(uploaded_img)
        output_path = dirpath / Path(uploaded_src)
        output_img.save(output_path)
        return {"src": str(output_path), "width": "500px"}

        

app = App(app_ui, server)