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

use futures::channel::mpsc;
use futures::prelude::*;
use gloo::storage::{LocalStorage, Storage as _};
use wasm_bindgen::prelude::*;
use wasm_bindgen::JsCast;
use wasm_bindgen_futures::*;
use web_sys::*;

mod history;
mod ocr;

use history::{History, NoETA};

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 is_connection_error(image: &GrayImage) -> bool {
    // prior experiments show that the 80th percentile is like 20 and the 100th percentile is 51 for the error state
    let pct_80 = imageproc::stats::percentile(image, 80);
    let pct_100 = imageproc::stats::percentile(image, 100);

    pct_80 < 25 && pct_100 < 60
}

fn update_target_marker(
    target_marker: &HtmlElement,
    width: &Rc<Cell<u32>>,
    height: &Rc<Cell<u32>>,
    video: &HtmlVideoElement,
    queue_position: &QueuePosition,
) {
    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();
}

#[derive(Clone)]
struct QueuePosition {
    inner: Rc<Cell<(u32, u32)>>,
}

impl QueuePosition {
    const STORAGE_KEY: &'static str = "queue-position";

    fn new() -> Self {
        let values = LocalStorage::get(Self::STORAGE_KEY).unwrap_or((920, 520));
        Self {
            inner: Rc::new(Cell::new(values)),
        }
    }

    fn set(&self, data: (u32, u32)) {
        LocalStorage::set(Self::STORAGE_KEY, data).unwrap();
        self.inner.replace(data);
    }

    fn get(&self) -> (u32, u32) {
        self.inner.get()
    }
}

enum Status {
    ETAPending,
    HasETA(js_sys::Date),
    ETAFucked,
    ConnectionError,
}

impl Status {
    fn render_title(&self) -> String {
        match self {
            Status::ETAPending => format!("queue go brrr - ETA pending"),
            Status::ETAFucked => format!("queue go brrr - ETA fucked (try reloading i guess?)"),
            Status::HasETA(date) => {
                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, &date).unwrap();
                let locale_string = locale_string.as_string().unwrap();
                format!("queue go brrr - ETA {}", &locale_string)
            }
            Status::ConnectionError => format!("queue go brrr - connection error?"),
        }
    }
}

#[derive(Clone)]
struct State {
    history: Rc<RefCell<History>>,
    status: Rc<RefCell<Status>>,
    queue_position: QueuePosition,
    preview_image: Element,
    current_queue_position: HtmlElement,
    title_h1: HtmlElement,
    title_element: HtmlElement,
}

impl State {
    fn new(queue_position: &QueuePosition) -> Self {
        let document = gloo::utils::document();
        let preview_image = document.get_element_by_id("photo").unwrap();
        let current_queue_position = document
            .get_element_by_id("current-queue-position")
            .unwrap()
            .dyn_into()
            .unwrap();
        let title_h1 = document
            .get_element_by_id("title")
            .unwrap()
            .dyn_into()
            .unwrap();
        let title_element = document
            .query_selector("title")
            .unwrap()
            .unwrap()
            .dyn_into()
            .unwrap();
        Self {
            history: Rc::new(RefCell::new(History::default())),
            status: Rc::new(RefCell::new(Status::ETAPending)),
            queue_position: queue_position.clone(),
            preview_image,
            current_queue_position,
            title_h1,
            title_element,
        }
    }

    async fn update(&self, data: Blob) {
        let image = blob_to_image(data).await;
        let useful_region = get_queue_size(image, &self.queue_position.get());
        let data_uri = image_to_data_uri(&useful_region);
        self.preview_image.set_attribute("src", &data_uri).unwrap();
        let useful_region = image::imageops::grayscale(&useful_region);
        let new_status = if is_connection_error(&useful_region) {
            Status::ConnectionError
        } else {
            let queue_size = ocr::ocr(&useful_region);
            match queue_size {
                Some(queue_size) => {
                    self.current_queue_position
                        .set_inner_text(&format!("{}", queue_size));
                    match self.history.try_borrow_mut() {
                        Ok(mut history) => {
                            history.record(queue_size);
                            let estimated_finish = history.completion_time();
                            match estimated_finish {
                                Ok(finish) => Status::HasETA(finish),
                                Err(NoETA::Pending) => Status::ETAPending,
                                Err(NoETA::Fuck) => Status::ETAFucked,
                            }
                        }
                        Err(_) => return,
                    }
                }
                None => {
                    self.current_queue_position
                        .set_inner_text("something i can't read");
                    return;
                }
            }
        };
        let title = new_status.render_title();
        self.title_h1.set_inner_text(&title);
        self.title_element.set_inner_text(&title);
    }
}

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 = QueuePosition::new();

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

    let state = State::new(&queue_position);

    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.set((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 state = state.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 state = state.clone();
                    spawn_local(async move {
                        state.update(data).await;
                    });
                })
                .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());
}