use image::{DynamicImage, ImageFormat};
use std::cell::{Cell, RefCell};
use std::rc::Rc;

use futures::channel::mpsc;
use futures::prelude::*;
use wasm_bindgen::prelude::*;
use wasm_bindgen::JsCast;
use wasm_bindgen_futures::*;
use web_sys::*;

mod history;
mod ocr;

// When the `wee_alloc` feature is enabled, use `wee_alloc` as the global
// allocator.
#[cfg(feature = "wee_alloc")]
#[global_allocator]
static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;

async fn blob_to_image(blob: Blob) -> DynamicImage {
    let image_data = gloo::file::futures::read_as_bytes(&blob.into())
        .await
        .unwrap();
    image::load_from_memory_with_format(&image_data, ImageFormat::Png).unwrap()
}

fn image_to_data_uri(image: &DynamicImage) -> String {
    let mut result = String::from("data:image/png;base64,");
    let mut enc = base64::write::EncoderStringWriter::from(&mut result, base64::STANDARD);
    image.write_to(&mut enc, ImageFormat::Png).unwrap();
    let _ = enc.into_inner();
    result
}

const QUEUE_SIZE_WIDTH: u32 = 70;
const QUEUE_SIZE_HEIGHT: u32 = 20;

fn get_queue_size(image: DynamicImage, corner: &(u32, u32)) -> DynamicImage {
    let &(x, y) = corner;
    let useful_region = image.crop_imm(x, y, QUEUE_SIZE_WIDTH, QUEUE_SIZE_HEIGHT);

    useful_region
}

fn update_target_marker(
    target_marker: &HtmlElement,
    width: &Rc<Cell<u32>>,
    height: &Rc<Cell<u32>>,
    video: &HtmlVideoElement,
    queue_position: &Rc<Cell<(u32, u32)>>,
) {
    let (real_x, real_y) = queue_position.get();
    let real_width = width.get() as f64;
    let real_height = height.get() as f64;
    let fake_width = video.offset_width() as f64;
    let fake_height = video.offset_height() as f64;
    let fake_x = real_x as f64 / real_width * fake_width;
    let fake_y = real_y as f64 / real_height * fake_height;

    let target_width = QUEUE_SIZE_WIDTH as f64 / real_width * fake_width;
    let target_height = QUEUE_SIZE_HEIGHT as f64 / real_height * fake_height;

    let style = target_marker.style();
    style
        .set_property("left", &format!("{}px", fake_x))
        .unwrap();
    style.set_property("top", &format!("{}px", fake_y)).unwrap();
    style
        .set_property("width", &format!("{}px", target_width))
        .unwrap();
    style
        .set_property("height", &format!("{}px", target_height))
        .unwrap();
}

async fn do_boot() {
    let width = Rc::new(Cell::new(0));
    let height = Rc::new(Cell::new(0));

    let streaming = Rc::new(Cell::new(false));

    let queue_position = Rc::new(Cell::new((920u32, 520u32)));

    let document = gloo::utils::document();

    let history = Rc::new(RefCell::new(history::History::default()));

    let (manual_update_tx, manual_update_rx) = mpsc::channel::<()>(5);

    let video: HtmlVideoElement = document
        .get_element_by_id("video")
        .unwrap()
        .dyn_into()
        .unwrap();
    let canvas: HtmlCanvasElement = document
        .get_element_by_id("canvas")
        .unwrap()
        .dyn_into()
        .unwrap();
    let target_marker: HtmlElement = document
        .get_element_by_id("target-marker")
        .unwrap()
        .dyn_into()
        .unwrap();

    let video_click_listener = {
        let video = video.clone();
        let also_video = video.clone();
        let queue_position = queue_position.clone();
        let width = width.clone();
        let height = height.clone();
        let target_marker = target_marker.clone();
        let manual_update_tx = manual_update_tx.clone();
        gloo::events::EventListener::new(&video, "click", move |event| {
            let mut manual_update_tx = manual_update_tx.clone();
            let video = also_video.clone();
            let mouse_event: &MouseEvent = event.dyn_ref().unwrap();
            let mouse_x = mouse_event.offset_x() as f64;
            let mouse_y = mouse_event.offset_y() as f64;
            let real_width = width.get() as f64;
            let real_height = height.get() as f64;
            let fake_width = video.offset_width() as f64;
            let fake_height = video.offset_height() as f64;
            let real_x = mouse_x / fake_width * real_width - QUEUE_SIZE_WIDTH as f64 / 2.0;
            let real_y = mouse_y / fake_height * real_height - QUEUE_SIZE_HEIGHT as f64 / 2.0;
            queue_position.replace((real_x.round() as u32, real_y.round() as u32));
            update_target_marker(&target_marker, &width, &height, &video, &queue_position);
            spawn_local(async move { manual_update_tx.send(()).await.unwrap() });
        })
    };
    video_click_listener.forget();

    let navigator = gloo::utils::window().navigator();
    let media_devices = navigator.media_devices().unwrap();
    let constraints = {
        let mut constraints = DisplayMediaStreamConstraints::new();
        constraints.audio(&JsValue::FALSE);
        constraints.video(&JsValue::TRUE);
        constraints
    };
    let capture_stream_promise = media_devices
        .get_display_media_with_constraints(&constraints)
        .unwrap();
    let capture_stream = JsFuture::from(capture_stream_promise).await.unwrap();
    let capture_stream: MediaStream = capture_stream.dyn_into().unwrap();
    video.set_src_object(Some(&capture_stream));
    let video_play_listener = {
        let width = width.clone();
        let height = height.clone();
        let streaming = streaming.clone();
        let video = video.clone();
        let also_video = video.clone();
        let canvas = canvas.clone();
        let queue_position = queue_position.clone();
        let manual_update_tx = manual_update_tx.clone();
        gloo::events::EventListener::new(&video, "canplay", move |_event| {
            let mut manual_update_tx = manual_update_tx.clone();
            let video = also_video.clone();
            let _ = video.play().unwrap();
            if !streaming.get() {
                width.set(video.video_width());
                height.set(video.video_height());
                canvas.set_attribute("width", &format!("{}", width.get()));
                canvas.set_attribute("height", &format!("{}", height.get()));
                streaming.set(true);
                update_target_marker(&target_marker, &width, &height, &video, &queue_position);
                spawn_local(async move { manual_update_tx.send(()).await.unwrap() });
            }
        })
    };
    video_play_listener.forget();

    let update_stream = futures::stream_select!(
        gloo::timers::future::IntervalStream::new(2_000),
        manual_update_rx,
    );
    let update_future = update_stream.for_each(move |_| {
        let history = history.clone();
        let queue_position = queue_position.clone();
        if !streaming.get() {
            return futures::future::ready(());
        }
        let context = canvas.get_context("2d").unwrap().unwrap();
        let context: CanvasRenderingContext2d = context.dyn_into().unwrap();
        canvas.set_width(width.get());
        canvas.set_height(height.get());
        context
            .draw_image_with_html_video_element_and_dw_and_dh(
                &video,
                0.0,
                0.0,
                width.get().into(),
                height.get().into(),
            )
            .unwrap();

        canvas
            .to_blob(
                Closure::once_into_js(move |data: Blob| {
                    let history = history.clone();
                    let queue_position = queue_position.clone();
                    // lifetime bullshit here
                    let document = gloo::utils::document();
                    let photo = document.get_element_by_id("photo").unwrap();
                    let current_queue_position: HtmlElement = document
                        .get_element_by_id("current-queue-position")
                        .unwrap()
                        .dyn_into()
                        .unwrap();
                    let eta: HtmlElement = document
                        .get_element_by_id("eta")
                        .unwrap()
                        .dyn_into()
                        .unwrap();
                    spawn_local(async move {
                        let image = blob_to_image(data).await;
                        let useful_region = get_queue_size(image, &queue_position.get());
                        let data_uri = image_to_data_uri(&useful_region);
                        photo.set_attribute("src", &data_uri).unwrap();
                        let queue_size = ocr::ocr(useful_region);
                        match queue_size {
                            Some(queue_size) => {
                                current_queue_position.set_inner_text(&format!("{}", queue_size));
                                if let Ok(mut history) = history.try_borrow_mut() {
                                    history.record(queue_size);
                                    let estimated_finish = history.completion_time();
                                    let eta_text = match estimated_finish {
                                        Some(finish) => {
                                            let empty_array = js_sys::Array::new();
                                            let options = {
                                                let kv_pair = js_sys::Array::new();
                                                kv_pair.push(&JsValue::from("timeStyle"));
                                                kv_pair.push(&JsValue::from("short"));
                                                let kv_pairs = js_sys::Array::new();
                                                kv_pairs.push(&kv_pair);
                                                js_sys::Object::from_entries(&kv_pairs).unwrap()
                                            };
                                            let format = js_sys::Intl::DateTimeFormat::new(
                                                &empty_array,
                                                &options,
                                            );
                                            let format = format.format();
                                            let locale_string =
                                                format.call1(&JsValue::UNDEFINED, &finish).unwrap();
                                            locale_string.as_string().unwrap()
                                        }
                                        None => format!("pending"),
                                    };
                                    let label = format!(" - ETA {}", eta_text);
                                    eta.set_inner_text(&label);
                                }
                            }
                            None => {
                                current_queue_position.set_inner_text("something i can't read");
                            }
                        }
                    });
                })
                .dyn_ref()
                .unwrap(),
            )
            .unwrap();
        futures::future::ready(())
    });
    spawn_local(update_future);
}

#[wasm_bindgen]
pub fn boot() {
    console_error_panic_hook::set_once();

    spawn_local(do_boot());
}