"use strict";
const HTMLElementImpl = require("./HTMLElement-impl").implementation;
const notImplemented = require("../../browser/not-implemented");
const idlUtils = require("../generated/utils");
const Canvas = require("../../utils").Canvas;

class HTMLCanvasElementImpl extends HTMLElementImpl {
  _attrModified(name, value) {
    if (this._canvas && (name === "width" || name === "height")) {
      this._canvas[name] = parseInt(value);
    }

    return super._attrModified.apply(this, arguments);
  }

  _getCanvas() {
    if (Canvas && !this._canvas) {
      this._canvas = new Canvas(this.width, this.height);
    }
    return this._canvas;
  }

  getContext(contextId) {
    const canvas = this._getCanvas();
    if (canvas) {
      if (!this._context) {
        this._context = canvas.getContext(contextId) || null;
        if (this._context) {
          // Override the native canvas reference with our wrapper. This is the
          // reason why we need to locally cache _context, since each call to
          // canvas.getContext(contextId) would replace this reference again.
          // Perhaps in the longer term, a better solution would be to create a
          // full wrapper for the Context object as well.
          this._context.canvas = idlUtils.wrapperForImpl(this);
          wrapNodeCanvasMethod(this._context, "createPattern");
          wrapNodeCanvasMethod(this._context, "drawImage");
        }
      }
      return this._context;
    }

    notImplemented("HTMLCanvasElement.prototype.getContext (without installing the canvas npm package)",
      this._ownerDocument._defaultView);
    return null;
  }

  probablySupportsContext(contextId) {
    const canvas = this._getCanvas();
    return canvas ? contextId === "2d" : false;
  }

  setContext() {
    notImplemented("HTMLCanvasElement.prototype.setContext");
  }

  toDataURL() {
    const canvas = this._getCanvas();
    if (canvas) {
      return canvas.toDataURL.apply(this._canvas, arguments);
    }

    notImplemented("HTMLCanvasElement.prototype.toDataURL (without installing the canvas npm package)",
      this._ownerDocument._defaultView);
    return null;
  }

  toBlob(callback, type, qualityArgument) {
    const window = this._ownerDocument._defaultView;
    const canvas = this._getCanvas();
    if (canvas) {
      let stream;
      switch (type) {
        case "image/jpg":
        case "image/jpeg":
          stream = canvas.createJPEGStream({
            quality: Math.min(0, Math.max(1, qualityArgument)) * 100
          });
          break;
        default:
          // TODO: Patch node-canvas to receive qualityArgument for PNG stream
          type = "image/png";
          stream = canvas.createPNGStream();
      }
      const buffers = [];
      stream.on("data", chunk => {
        buffers.push(chunk);
      });
      stream.on("end", () => {
        callback(new window.Blob(buffers, { type }));
      });
    } else {
      notImplemented("HTMLCanvasElement.prototype.toBlob (without installing the canvas npm package)",
        window);
    }
  }

  get width() {
    const parsed = parseInt(this.getAttribute("width"));
    return isNaN(parsed) || parsed < 0 || parsed > 2147483647 ? 300 : parsed;
  }

  set width(v) {
    v = v > 2147483647 ? 300 : v;
    this.setAttribute("width", String(v));
  }

  get height() {
    const parsed = parseInt(this.getAttribute("height"));
    return isNaN(parsed) || parsed < 0 || parsed > 2147483647 ? 150 : parsed;
  }

  set height(v) {
    v = v > 2147483647 ? 150 : v;
    this.setAttribute("height", String(v));
  }
}

// We need to wrap the methods that receive an image or canvas object
// (luckily, always as the first argument), so that these objects can be
// unwrapped an the expected types passed.
function wrapNodeCanvasMethod(ctx, name) {
  const prev = ctx[name];
  ctx[name] = function (image) {
    const impl = idlUtils.implForWrapper(image);
    if (impl) {
      arguments[0] = impl._image || impl._canvas;
    }
    return prev.apply(ctx, arguments);
  };
}

module.exports = {
  implementation: HTMLCanvasElementImpl
};
