import {
    world,
    select,
    running,
    play,
    step,
    pause,
    selected,
} from "./index.js";

export const canvas = document.getElementById("main-canvas");
export const ctx = canvas.getContext("2d");

// let world = World.new();
let cx = 0;
let cy = 0;
let zoom = 1;
let grid = true;

let click_x = 0, click_y = 0;
let mouse_x = 0, mouse_y = 0;
let mouse_down = false;
let hovered = false;

let start = performance.now();

export function draw() {
    world.set_blink_duration((performance.now() - start) / 1000.0);
    let zoom_factor = Math.ceil(Math.pow(2, zoom));
    let tile_size = 10 * zoom_factor;
    ctx.fillStyle = "#202027";
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    function stroke_rect(x, y, width, height) {
        ctx.lineWidth = zoom_factor;
        ctx.strokeRect(
            Math.round(x * tile_size + cx + canvas.width / 2) - zoom_factor * 1.5,
            Math.round(y * tile_size + cy + canvas.height / 2) - zoom_factor * 1.5,
            Math.round(width * tile_size) + zoom_factor * 2,
            Math.round(height * tile_size) + zoom_factor * 2,
        );
    }

    function fill_rect(x, y, width, height) {
        ctx.fillRect(
            Math.round(x * tile_size + cx + canvas.width / 2) - zoom_factor * 1,
            Math.round(y * tile_size + cy + canvas.height / 2) - zoom_factor * 1,
            Math.round(width * tile_size) + zoom_factor * 1,
            Math.round(height * tile_size) + zoom_factor * 1,
        );
    }

    let panes = [];

    for (let name of world.panes()) {
        let pane = world.get_pane(name);

        panes.push({
            x: pane.x,
            y: pane.y,
            width: pane.width,
            height: pane.height
        });

        ctx.strokeStyle = "rgba(128, 128, 128, 0.5)";
        stroke_rect(
            pane.x,
            pane.y,
            pane.width,
            pane.height,
        );

        pane.free();
    }

    let from_y = Math.floor((-cy - canvas.height / 2) / tile_size);
    let to_y = Math.ceil((-cy + canvas.height / 2) / tile_size);
    let from_x = Math.floor((-cx - canvas.width / 2) / tile_size);
    let to_x = Math.ceil((-cx + canvas.width / 2) / tile_size);

    let width = to_x - from_x + 1;
    let height = to_y - from_y + 1;

    // TODO: memoize
    let chars = world.draw(-from_x, -from_y, width, height);
    ctx.textAlign = "left";
    ctx.textBaseline = "top";
    ctx.font = `${tile_size}px Stackline Classic`;

    for (let y = from_y; y <= to_y; y++) {
        for (let x = from_x; x <= to_x; x++) {
            let x2 = x * tile_size + cx + canvas.width / 2;
            let y2 = y * tile_size + cy + canvas.height / 2;

            let index = 3 * (width * (y - from_y) + x - from_x);

            let ch = String.fromCharCode(chars[index]);
            if (ch !== " ") {
                let fg = to_color(chars[index + 1]);
                let bg = chars[index + 2] === 0 ? null : to_color(chars[index + 2]);

                if (bg) {
                    ctx.fillStyle = `rgba(${bg.join(",")})`;
                    ctx.fillRect(
                        Math.round(x2),
                        Math.round(y2),
                        Math.round(x2 + tile_size) - Math.round(x2),
                        Math.round(y2 + tile_size) - Math.round(y2),
                    );
                }
                ctx.fillStyle = `rgba(${fg.join(",")})`;
                ctx.fillText(
                    ch,
                    Math.round(x2),
                    Math.round(y2),
                );
            } else if (grid) {
                // Draw grid
                let inside = false;

                for (let pane of panes) {
                    if (x >= pane.x && x < pane.x + pane.width && y >= pane.y && y < pane.y + pane.height) {
                        inside = true;
                        break;
                    }
                }

                if (inside || width < 100 && height < 100) {
                    ctx.fillStyle = inside ? "#404040" : "#303030";

                    ctx.fillRect(
                        Math.round(x2 + tile_size / 2) - zoom_factor,
                        Math.round(y2 + tile_size / 2) - zoom_factor,
                        zoom_factor,
                        zoom_factor
                    );
                }
            }
        }
    }

    if (hovered) {
        let [x, y] = get_hovered();

        ctx.strokeStyle = "rgba(230, 255, 230, 0.2)";
        ctx.fillStyle = "rgba(230, 255, 230, 0.07)";
        stroke_rect(x, y, 1, 1);
        fill_rect(x, y, 1, 1);
    }

    if (selected) {
        let [x, y] = selected;
        ctx.strokeStyle = "rgba(230, 230, 255, 0.1)";
        stroke_rect(x, y, 1, 1);
    }
}

export function resize() {
    canvas.width = canvas.clientWidth;
    canvas.height = canvas.clientHeight;

    draw();
}

export function loop() {
    draw();
    window.requestAnimationFrame(loop);
}

export function init() {
    canvas.addEventListener("mousedown", (evt) => {
        click_x = mouse_x = evt.clientX - canvas.offsetLeft;
        click_y = mouse_y = evt.clientY - canvas.offsetTop;
        mouse_down = true;
    });

    canvas.addEventListener("mousemove", (evt) => {
        hovered = true;

        if (mouse_down) {
            // TODO: numerically stable solution
            cx += (evt.clientX - canvas.offsetLeft) - mouse_x;
            cy += (evt.clientY - canvas.offsetTop) - mouse_y;
        }

        mouse_x = evt.clientX - canvas.offsetLeft;
        mouse_y = evt.clientY - canvas.offsetTop;
    });

    canvas.addEventListener("mouseup", (evt) => {
        mouse_down = false;

        let dist = Math.sqrt((mouse_x - click_x) ** 2 + (mouse_y - click_y) ** 2);
        if (dist < 10) {
            select(...get_hovered());
        }
    });

    canvas.addEventListener("mouseenter", (evt) => {
        hovered = true;
    });

    canvas.addEventListener("mouseleave", (evt) => {
        mouse_down = false;
        hovered = false;
    });

    canvas.addEventListener("wheel", (event) => {
        const ZOOM_STRENGTH = -0.005;
        let old_zoom = zoom;
        zoom += event.deltaY * ZOOM_STRENGTH;
        zoom = Math.min(Math.max(zoom, 0.0), 4.0);

        let delta = Math.ceil(Math.pow(2, zoom)) / Math.ceil(Math.pow(2, old_zoom));
        cx *= delta;
        cy *= delta;
    });

    window.addEventListener("keydown", (event) => {
        if (hovered) {
            if (event.code === "Space") {
                if (running) {
                    pause();
                } else if (event.shiftKey) {
                    play();
                } else {
                    step();
                }
            } else if (event.code === "KeyG") {
                grid = !grid;
            }
        }
    });


    resize();
    window.addEventListener("resize", resize);
    window.requestAnimationFrame(loop);
}

export function get_hovered() {
    let zoom_factor = Math.ceil(Math.pow(2, zoom));
    let tile_size = 10 * zoom_factor;

    let x = Math.floor((mouse_x - canvas.width / 2 - cx) / tile_size);
    let y = Math.floor((mouse_y - canvas.height / 2 - cy) / tile_size);

    return [x, y];
}

export function to_color(num) {
    let alpha = (num >> 24) & 0xff;
    let red = (num >> 16) & 0xff;
    let green = (num >> 8) & 0xff;
    let blue = num & 0xff;

    return [red, green, blue, alpha];
}