import { Vec2 } from "./common.js"
import { Graphics } from "./graphics.js";
import { Color } from "./common.js";

function drawTriangle(gfx: Graphics, positions: [Vec2, Vec2, Vec2], color: Color) {
    const a_position = gfx.getAttribute("a_position");
    const a_color = gfx.getAttribute("a_color");

    const points: Array<number> = [
        positions[0].x, positions[0].y,
        positions[1].x, positions[1].y,
        positions[2].x, positions[2].y,
    ]

    const colors: Array<number[]> = [
        color,
        color,
        color,
    ];

    a_position.data(gfx.ctx, points, gfx.ctx.STATIC_DRAW);
    a_color.data(gfx.ctx, colors.flat(), gfx.ctx.STATIC_DRAW);
    gfx.ctx.drawArrays(gfx.ctx.TRIANGLES, 0, 3);
}

function drawTriangleExts(gfx: Graphics, position: Vec2, exts: Vec2, color: Color) {
    const a_position = gfx.getAttribute("a_position");
    const a_color = gfx.getAttribute("a_color");

    const points: Array<number> = [
        position.x, position.y,
        position.x + exts.x, position.y,
        position.x, position.y + exts.y,
    ]

    const colors: Array<number[]> = [
        color,
        color,
        color,
    ];

    a_position.data(gfx.ctx, points, gfx.ctx.STATIC_DRAW);
    a_color.data(gfx.ctx, colors.flat(), gfx.ctx.STATIC_DRAW);
    gfx.ctx.drawArrays(gfx.ctx.TRIANGLES, 0, 3);
}

function drawRectangle(gfx: Graphics, position: Vec2, exts: Vec2, color: Color) {
    const a_position = gfx.getAttribute("a_position");
    const a_color = gfx.getAttribute("a_color");

    const points: Array<number> = [
        position.x, position.y,
        position.x + exts.x, position.y,
        position.x, position.y + exts.y,
        
        position.x + exts.x, position.y + exts.y,
        position.x + exts.x, position.y,
        position.x, position.y + exts.y,
    ]

    const colors: Array<number[]> = [
        color,
        color,
        color,
        color,
        color,
        color,
    ];

    a_position.data(gfx.ctx, points, gfx.ctx.STATIC_DRAW);
    a_color.data(gfx.ctx, colors.flat(), gfx.ctx.STATIC_DRAW);
    gfx.ctx.drawArrays(gfx.ctx.TRIANGLES, 0, 6);

}

function drawCircle(gfx: Graphics, position: Vec2, radius: number, color: Color) {
    const points: Array<Vec2> = new Array<Vec2>();

    const precision = 40;
    const angle = 2.0*Math.PI/precision;
    let a = 0;
    for (let i = 0; i < precision; ++i) {
        var vec = Vec2.angle(a);
        vec.mult(radius);
        a += angle;
        points.push(vec);
    }

    for (let i = 0; i < points.length; i++) {
        const current = points[i];
        const next = points[(i + 1) % points.length];
        let center = position;
        drawTriangle(gfx, [center, center.addNew(current), center.addNew(next)], color);
    }
}

function drawLine(gfx: Graphics, A: Vec2, B: Vec2, color: Color) {
    const a_position = gfx.getAttribute("a_position");
    const a_color = gfx.getAttribute("a_color");

    let points: Array<number> = [
        A.x, A.y,
        B.x, B.y,
    ];

    const colors: Array<number[]> = [
        color,
        color,
    ];

    a_position.data(gfx.ctx, points, gfx.ctx.STATIC_DRAW);
    a_color.data(gfx.ctx, colors.flat(), gfx.ctx.STATIC_DRAW);
    gfx.ctx.drawArrays(gfx.ctx.LINES, 0, 2);
}

export { drawTriangle, drawTriangleExts, drawRectangle, drawCircle, drawLine }