#![feature(clamp)]

use bitsy_parser::game::Game;
use bitsy_parser::image::Image;
use bitsy_parser::tile::Tile;
use image::{GenericImageView, Pixel, DynamicImage};
use image::imageops::ColorMap;
use image::imageops::FilterType::CatmullRom;
use lazy_static::lazy_static;
use std::sync::Mutex;
use wasm_bindgen::prelude::*;

mod colour_map;

use colour_map::ColourMap;

const SD: u32 = 8;

enum SelectedPalette {
    None,
    Existing {
        id: String,
    },
    New {
        background: bitsy_parser::Colour,
        foreground: bitsy_parser::Colour,
    }
}

struct State {
    game:       Option<Game>,
    image:      Option<DynamicImage>,
    room_name:  Option<String>,
    palette:    SelectedPalette,
    dither:     bool,
    brightness: i32,
}

lazy_static! {
    static ref STATE: Mutex<State> = Mutex::new(
        State {
            game:       None,
            image:      None,
            room_name:  None,
            palette:    SelectedPalette::None,
            dither:     true,
            brightness: 0,
        }
    );
}

fn tile_name(prefix: &Option<String>, index: &u32) -> Option<String> {
    if let Some(prefix) = prefix {
        Some(format!("{} {}", prefix, index))
    } else {
        None
    }
}

#[wasm_bindgen]
pub fn load_default_game()  {
    let mut state = STATE.lock().unwrap();

    state.game = Some(bitsy_parser::mock::game_default());

    // yes, this will probably always just be "0", but to be safe…
    state.palette = SelectedPalette::Existing {
        id: bitsy_parser::mock::game_default().palette_ids()[0].clone()
    }
}

#[wasm_bindgen]
pub fn load_game(game_data: String) -> String {
    let mut state = STATE.lock().unwrap();

    let result = Game::from(game_data);

    match result {
        Ok((game, _errs)) => {
            let palette_id = game.palette_ids()[0].clone();
            state.game    = Some(game);
            state.palette = SelectedPalette::Existing { id: palette_id };
            format!("Loaded game")
        },
        _ => {
            state.game    = None;
            state.palette = SelectedPalette::None;
            format!("{}", result.err().unwrap())
        }
    }
}

#[wasm_bindgen]
pub fn load_image(image_base64: String) -> String {
    let mut state = STATE.lock().expect("Couldn't lock application state");

    let image_base64: Vec<&str> = image_base64.split("base64,").collect();
    let image_base64 = image_base64[1];

    match base64::decode(image_base64) {
        Ok(image) => {
            match image::load_from_memory(image.as_ref()) {
                Ok(image) => {
                    // todo get rid of magic numbers! what about Bitsy HD?
                    let image = image.resize(128, 128, CatmullRom);
                    state.image = Some(image);
                    "OK"
                },
                _ => {
                    state.image = None;
                    "Couldn't load image"
                }
            }
        },
        _ => {
            state.image = None;
            "Couldn't decode image"
        }
    }.to_string()
}

#[wasm_bindgen]
pub fn set_dither(dither: bool) {
    let mut state = STATE.lock().unwrap();
    state.dither = dither;
}

#[wasm_bindgen]
pub fn set_palette(palette_id: &str, background: String, foreground: String) {
    let mut state = STATE.lock().unwrap();

    state.palette = match palette_id {
        "NEW_PALETTE" => SelectedPalette::New {
            background: bitsy_parser::Colour::from_hex(&background).unwrap(),
            foreground: bitsy_parser::Colour::from_hex(&foreground).unwrap(),
        },
        "" => SelectedPalette::None,
        _             => SelectedPalette::Existing { id: palette_id.to_string() },
    }
}

#[wasm_bindgen]
pub fn set_room_name(room_name: String) {
    let mut state = STATE.lock().unwrap();

    match room_name.is_empty() {
        true  => { state.room_name = None },
        false => { state.room_name = Some(room_name) },
    }
}

#[wasm_bindgen]
pub fn set_brightness(brightness: i32) {
    let mut state = STATE.lock().unwrap();
    state.brightness = brightness;
}

#[wasm_bindgen]
pub fn get_palettes() -> String {
    let state = STATE.lock().unwrap();

    let mut palette_objects = json::JsonValue::new_array();

    for palette in &state.game.as_ref().unwrap().palettes {
        let mut object = json::JsonValue::new_object();

        object.insert("id", palette.id.clone()).unwrap();

        object.insert(
            "name",
            palette.name.clone().unwrap_or(
                format!("Palette {}", palette.id))
        ).unwrap();

        palette_objects.push(object).unwrap();
    }

    json::stringify(palette_objects)
}

fn image_to_base64(image: &DynamicImage) -> String {
    let mut bytes: Vec<u8> = Vec::new();
    image.write_to(&mut bytes, image::ImageOutputFormat::Png).unwrap();
    format!("data:image/png;base64,{}", base64::encode(&bytes))
}

fn render_preview(state: &State) -> DynamicImage {
    let mut buffer = state.image.as_ref().unwrap().clone().into_rgba();

    let palette = match &state.palette {
        SelectedPalette::None => bitsy_parser::mock::game_default().palettes[0].clone(),
        SelectedPalette::Existing { id } => state.game.as_ref().unwrap().get_palette(id).unwrap().clone(),
        SelectedPalette::New { background, foreground } => bitsy_parser::Palette {
            id: "0".to_string(),
            name: None,
            colours: vec![
                background.clone(), foreground.clone(), bitsy_parser::Colour { red: 0, green: 0, blue: 0 }
            ],
        },
    };

    let colour_map = crate::ColourMap::from(&palette);

    // adjust brightness
    let mut buffer = image::imageops::brighten(&mut buffer, state.brightness);

    if state.dither {
        image::imageops::dither(&mut buffer, &colour_map);
    } else {
        // just do colour indexing
        let indices = image::imageops::colorops::index_colors(&mut buffer, &colour_map);

        // todo get rid of magic numbers! what about Bitsy HD?
        buffer = image::ImageBuffer::from_fn(128, 128, |x, y| -> image::Rgba<u8> {
            let p = indices.get_pixel(x, y);

            colour_map
                .lookup(p.0[0] as usize)
                .expect("indexed colour out-of-range")
                .into()
        });
    }

    image::DynamicImage::ImageRgba8(buffer)
}

#[wasm_bindgen]
pub fn get_preview() -> String {
    let state = STATE.lock().unwrap();

    match &state.image.is_some() {
        true  => image_to_base64(&render_preview(&state)),
        false => "".to_string(),
    }
}

#[wasm_bindgen]
pub fn add_room() -> String {
    let mut state = STATE.lock().expect("Couldn't lock application state");

    if state.game.is_none() {
        return "No game data loaded".to_string();
    }

    let mut game = state.game.clone().unwrap();

    if state.image.is_none() {
        return "No image loaded".to_string();
    }

    let width   = state.image.as_ref().unwrap().width();
    let height  = state.image.as_ref().unwrap().height();
    let columns = (width  as f64 / SD as f64).floor() as u32;
    let rows    = (height as f64 / SD as f64).floor() as u32;

    let mut tile_index = 1;

    for column in 0..columns {
        for row in 0..rows {
            let mut pixels = Vec::with_capacity(64);

            for y in (row * SD)..((row + 1) * SD) {
                for x in (column * SD)..((column + 1) * SD) {
                    let pixel = state.image.as_ref().unwrap().get_pixel(x, y).to_rgb();
                    let total = pixel[0] as u32 + pixel[1] as u32 + pixel[2] as u32;
                    // is each channel brighter than 128/255 on average?
                    pixels.push(if total >= 384 {1} else {0});
                }
            }

            let tile = Tile {
                // "0" will get overwritten to a new, safe tile ID
                id: "0".to_string(),
                name: tile_name(&state.room_name, &tile_index),
                wall: None,
                animation_frames: vec![Image { pixels }],
                colour_id: None
            };

            if !game.tiles.contains(&tile) {
                game.add_tile(tile.clone());

                tile_index += 1;
            }
        }
    }

    game.dedupe_tiles();

    state.game = Some(game.to_owned());

    "OK".to_string()
}

#[wasm_bindgen]
pub fn output() -> String {
    let state = STATE.lock().unwrap();

    match &state.game {
        Some(game) => game.to_string(),
        None => "No game loaded".to_string(),
    }
}

#[cfg(test)]
mod test {
    use crate::{add_room, load_image, load_default_game, output, get_preview};

    #[test]
    fn image_to_base64() {
        let image = image::load_from_memory(include_bytes!("test-resources/test.png")).unwrap();
        let output = crate::image_to_base64(&image);
        let expected = include_str!("test-resources/test.png.base64").trim();
        assert_eq!(output, expected);
    }

    #[test]
    fn get_palettes() {
        load_default_game();
        let output = crate::get_palettes();
        let expected = "[{\"id\":\"0\",\"name\":\"blueprint\"}]";
        assert_eq!(output, expected);
    }

    #[test]
    fn render_preview() {
        load_default_game();
        load_image(include_str!("test-resources/colour_input.png.base64").trim().to_string());
        let output = get_preview();
        let expected = include_str!("test-resources/colour_input.png.base64.greyscale").trim();
        assert_eq!(output, expected);
    }

    #[test]
    fn example() {
        load_default_game();
        load_image(include_str!("test-resources/test.png.base64").to_string());
        add_room();

        assert_eq!(output(), include_str!("test-resources/expected.bitsy"));
    }
}