require("ol/ol.css");

const { Map, View } = require("ol");
const { getVectorContext } = require("ol/render");
const Point = require("ol/geom/Point").default;
const proj = require("ol/proj");
const { Style, Icon } = require("ol/style");
const tilesLayers = require("./tiles");
const networkLayers = require("./network");
const { sizes, makeBorderColor, makeCourseColor } = require("./common");
const network = require("../../tam/network.json");
const simulation = require("../../tam/simulation");

const courseStyles = {};

const getCourseStyle = lineColor => {
    if (!(lineColor in courseStyles)) {
        const icon = window.document.createElement("canvas");

        const shapeSize = sizes.courseSize;
        const iconSize = sizes.courseSize + sizes.courseOuterBorder;

        icon.width = iconSize;
        icon.height = iconSize;

        const cx = icon.width / 2;
        const cy = icon.height / 2;

        const iconCtx = icon.getContext("2d");

        for (const [color, size] of [
            [makeBorderColor(lineColor), sizes.courseOuterBorder],
            [lineColor, sizes.courseBorder],
            [makeCourseColor(lineColor), sizes.courseInnerBorder]
        ]) {
            iconCtx.fillStyle = color;
            iconCtx.strokeStyle = color;
            iconCtx.lineWidth = size;
            iconCtx.lineJoin = "round";
            iconCtx.miterLimit = 200000;

            iconCtx.beginPath();
            iconCtx.moveTo(cx - 0.5 * shapeSize, cy - 0.3 * shapeSize);
            iconCtx.lineTo(cx + 0.5 * shapeSize, cy);
            iconCtx.lineTo(cx - 0.5 * shapeSize, cy + 0.3 * shapeSize);
            iconCtx.closePath();
            iconCtx.stroke();
            iconCtx.fill();
        }

        courseStyles[lineColor] = new Style({
            image: new Icon({
                img: icon,
                imgSize: [icon.width, icon.height]
            })
        });
    }

    return courseStyles[lineColor];
};

const create = target => {
    const view = new View({
        center: proj.fromLonLat([3.88, 43.605]),
        zoom: 14,
        maxZoom: 22,
        constrainResolution: true
    });

    const map = new Map({
        target,
        layers: [
            ...tilesLayers.getLayers(),
            ...networkLayers.getLayers()
        ],
        view
    });

    const stopsLayer = map.getLayers().item(3);

    // Run courses simulation
    const simulInstance = simulation.start();

    // Course on which the view is currently focused
    let focusedCourse = null;

    const startFocus = courseId => {
        if (courseId in simulInstance.courses) {
            const course = simulInstance.courses[courseId];

            view.animate({
                center: course.position,
                duration: 500
            }, () => {
                focusedCourse = courseId;
            });
        }
    };

    const stopFocus = () => {
        focusedCourse = null;
    };

    // Draw courses directly on the map
    map.on("postcompose", ev => {
        simulInstance.update();

        // The normal way to access a layer’s vector context is through the
        // `postrender` event of that layer. However, `postrender` is not
        // triggered when no feature of the layer is inside the current
        // bounding box, but we want to draw vehicles in between stops even
        // if no stop is visible. This hack listens to the global `postcompose`
        // event, which is always triggered at every frame, and reconstructs
        // the stops layer’s vector context from internal variables
        /* eslint-disable no-underscore-dangle */
        if (stopsLayer.renderer_) {
            ev.context = stopsLayer.renderer_.context;
            ev.inversePixelTransform =
                stopsLayer.renderer_.inversePixelTransform;
            /* eslint-enable no-underscore-dangle */

            const ctx = getVectorContext(ev);

            for (const course of Object.values(simulInstance.courses)) {
                const color = network.lines[course.line].color;
                const style = getCourseStyle(color);

                style.getImage().setRotation(
                    view.getRotation() +
                    course.angle
                );

                ctx.setStyle(style);

                const point = new Point(course.position);

                ctx.drawGeometry(point);

                if (course.id === focusedCourse) {
                    view.setCenter(course.position);
                }
            }
        }

        map.render();
    });

    map.render();

    map.on("singleclick", ev => {
        const mousePixel = map.getPixelFromCoordinate(ev.coordinate);
        const maxDistance = sizes.courseSize + sizes.courseOuterBorder;

        for (const course of Object.values(simulInstance.courses)) {
            const coursePixel = map.getPixelFromCoordinate(course.position);
            const dx = mousePixel[0] - coursePixel[0];
            const dy = mousePixel[1] - coursePixel[1];
            const distance = dx * dx + dy * dy;

            if (distance <= maxDistance * maxDistance) {
                startFocus(course.id);
                return;
            }
        }

        // Clicking anywhere else resets focus
        stopFocus();
    });

    return map;
};

exports.create = create;