aboutsummaryrefslogtreecommitdiff
path: root/src/content/presenters/FollowPresenter.ts
blob: 8aef819d9766dc3c717b24ff4c8699d53366f697 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
import Hint, { InputHint, LinkHint } from "./Hint";
import * as doms from "../../shared/utils/dom";

const TARGET_SELECTOR = [
  "a",
  "button",
  "input",
  "textarea",
  "area",
  "[contenteditable=true]",
  '[contenteditable=""]',
  "[tabindex]",
  '[role="button"]',
  "summary",
].join(",");

interface Size {
  width: number;
  height: number;
}

interface Point {
  x: number;
  y: number;
}

const inViewport = (
  win: Window,
  element: Element,
  viewSize: Size,
  framePosition: Point
): boolean => {
  const { top, left, bottom, right } = doms.viewportRect(element);
  const doc = win.document;
  const frameWidth = doc.documentElement.clientWidth;
  const frameHeight = doc.documentElement.clientHeight;

  if (right < 0 || bottom < 0 || top > frameHeight || left > frameWidth) {
    // out of frame
    return false;
  }
  if (
    right + framePosition.x < 0 ||
    bottom + framePosition.y < 0 ||
    left + framePosition.x > viewSize.width ||
    top + framePosition.y > viewSize.height
  ) {
    // out of viewport
    return false;
  }
  return true;
};

const isAriaHiddenOrAriaDisabled = (win: Window, element: Element): boolean => {
  if (!element || win.document.documentElement === element) {
    return false;
  }
  for (const attr of ["aria-hidden", "aria-disabled"]) {
    const value = element.getAttribute(attr);
    if (value !== null) {
      const hidden = value.toLowerCase();
      if (hidden === "" || hidden === "true") {
        return true;
      }
    }
  }
  return isAriaHiddenOrAriaDisabled(win, element.parentElement as Element);
};

export default interface FollowPresenter {
  getTargetCount(viewSize: Size, framePosition: Point): number;

  createHints(viewSize: Size, framePosition: Point, tags: string[]): void;

  filterHints(prefix: string): void;

  clearHints(): void;

  getHint(tag: string): Hint | undefined;
}

export class FollowPresenterImpl implements FollowPresenter {
  private hints: Hint[];

  constructor() {
    this.hints = [];
  }

  getTargetCount(viewSize: Size, framePosition: Point): number {
    const targets = this.getTargets(viewSize, framePosition);
    return targets.length;
  }

  createHints(viewSize: Size, framePosition: Point, tags: string[]): void {
    const targets = this.getTargets(viewSize, framePosition);
    const min = Math.min(targets.length, tags.length);
    for (let i = 0; i < min; ++i) {
      const target = targets[i];
      if (
        target instanceof HTMLAnchorElement ||
        target instanceof HTMLAreaElement
      ) {
        this.hints.push(new LinkHint(target, tags[i]));
      } else {
        this.hints.push(new InputHint(target, tags[i]));
      }
    }
  }

  filterHints(prefix: string): void {
    const shown = this.hints.filter((h) => h.getTag().startsWith(prefix));
    const hidden = this.hints.filter((h) => !h.getTag().startsWith(prefix));

    shown.forEach((h) => h.show());
    hidden.forEach((h) => h.hide());
  }

  clearHints(): void {
    this.hints.forEach((h) => h.remove());
    this.hints = [];
  }

  getHint(tag: string): Hint | undefined {
    return this.hints.find((h) => h.getTag() === tag);
  }

  private getTargets(viewSize: Size, framePosition: Point): HTMLElement[] {
    const all = window.document.querySelectorAll(TARGET_SELECTOR);
    const filtered = Array.prototype.filter.call(
      all,
      (element: HTMLElement) => {
        const style = window.getComputedStyle(element);

        // AREA's 'display' in Browser style is 'none'
        return (
          (element.tagName === "AREA" || style.display !== "none") &&
          style.visibility !== "hidden" &&
          (element as HTMLInputElement).type !== "hidden" &&
          element.offsetHeight > 0 &&
          !isAriaHiddenOrAriaDisabled(window, element) &&
          inViewport(window, element, viewSize, framePosition)
        );
      }
    );
    return filtered;
  }
}