import { EvHandler, EvHandlerRes, Mouse } from "./input.ts";
import { Renderer, RendererImage } from "./renderer.ts";

export class CanvasRenderer implements Renderer {
    constructor(
        private c: HTMLCanvasElement,
        private g: CanvasRenderingContext2D,
    ) {}

    get width(): number {
        return this.c.width;
    }
    get height(): number {
        return this.c.height;
    }

    clear(color: string): void {
        const { g } = this;
        g.fillStyle = color;
        g.fillRect(0, 0, this.c.width, this.c.height);
    }

    fillRect(x: number, y: number, w: number, h: number, color: string): void {
        const { g } = this;
        g.fillStyle = color;
        g.fillRect(x, y, w, h);
    }

    strokeRect(
        x: number,
        y: number,
        w: number,
        h: number,
        color: string,
        lineWidth: number,
    ): void {
        const { g } = this;
        g.strokeStyle = color;
        g.lineWidth = lineWidth;
        g.strokeRect(x, y, w, h);
    }

    fillCirc(x: number, y: number, radius: number, color: string): void {
        const { g } = this;
        g.fillStyle = color;
        g.beginPath();
        g.arc(x, y, radius, 0, Math.PI * 2);
        g.fill();
    }

    putImage(
        data: RendererImage,
        x: number,
        y: number,
        w = data.width,
        h = data.height,
        alpha = 1,
    ): void {
        const { g } = this;
        g.globalAlpha = alpha;
        g.drawImage(data, x, y, w, h);
        g.globalAlpha = 1.0;
    }
}

export class CanvasMouse implements Mouse {
    public x = 0;
    public y = 0;

    private pressHandlers: EvHandler[] = [];
    private releaseHandlers: EvHandler[] = [];
    private moveHandlers: EvHandler[] = [];
    private scrollHandlers: ((direction: "up" | "down") => EvHandlerRes)[] = [];

    constructor(c: HTMLCanvasElement) {
        c.onmousemove = (ev) => {
            this.x = ev.x;
            this.y = ev.y;
        };
        c.onmousedown = (ev) => {
            if (ev.button === 0) {
                this.runHandlers(this.pressHandlers);
            }
        };
        c.onmouseup = (ev) => {
            if (ev.button === 0) {
                this.runHandlers(this.releaseHandlers);
            }
        };
        c.onmousemove = (ev) => {
            this.x = ev.x;
            this.y = ev.y;
            this.runHandlers(this.moveHandlers);
        };
        c.onwheel = (ev) => {
            if (ev.deltaY !== 0) {
                this.runHandlers(
                    this.scrollHandlers,
                    ev.deltaY < 0 ? "up" : "down",
                );
            }
        };
    }

    private runHandlers<Args extends unknown[] = []>(
        handlers: EvHandler<Args>[],
        ...args: Args
    ) {
        for (const handler of handlers.toReversed()) {
            if (handler(...args) === "stop") {
                break;
            }
        }
    }

    addOnPress(handler: EvHandler) {
        this.pressHandlers.push(handler);
    }
    addOnRelease(handler: EvHandler) {
        this.releaseHandlers.push(handler);
    }
    addOnMove(handler: EvHandler) {
        this.moveHandlers.push(handler);
    }
    addOnScroll(handler: EvHandler<["up" | "down"]>) {
        this.scrollHandlers.push(handler);
    }
}