(core) move client code to core

Summary:
This moves all client code to core, and makes minimal fix-ups to
get grist and grist-core to compile correctly.  The client works
in core, but I'm leaving clean-up around the build and bundles to
follow-up.

Test Plan: existing tests pass; server-dev bundle looks sane

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2627

app/client/ui/UserImage.ts

@@ -0,0 +1,127 @@
+import {colors} from 'app/client/ui2018/cssVars';
+import {FullUser} from 'app/common/LoginSessionAPI';
+import {dom, DomElementArg, styled} from 'grainjs';
+
+export type Size = 'small' | 'medium' | 'large';
+
+/**
+ * Returns a DOM element showing a circular icon with a user's picture, or the user's initials if
+ * picture is missing. Also vares the color of the circle when using initials.
+ */
+export function createUserImage(user: FullUser|null, size: Size, ...args: DomElementArg[]): HTMLElement {
+  let initials: string;
+  return cssUserImage(
+    cssUserImage.cls('-' + size),
+    (!user || user.anonymous) ? cssUserImage.cls('-anon') :
+    [
+      (user.picture ? cssUserPicture({src: user.picture}, dom.on('error', (ev, el) => dom.hideElem(el, true))) : null),
+      dom.style('background-color', pickColor(user)),
+      (initials = getInitials(user)).length > 1 ? cssUserImage.cls('-reduced') : null,
+      initials!,
+    ],
+    ...args,
+  );
+}
+
+/**
+ * Extracts initials from a user, e.g. a FullUser. E.g. "Foo Bar" is turned into "FB", and
+ * "foo@example.com" into just "f".
+ *
+ * Exported for testing.
+ */
+export function getInitials(user: {name?: string, email?: string}) {
+  const source = (user.name && user.name.trim()) || (user.email && user.email.trim()) || '';
+  return source.split(/\s+/, 2).map(p => p.slice(0, 1)).join('');
+}
+
+/**
+ * Hashes the username to return a color.
+ */
+function pickColor(user: FullUser): string {
+  let c = hashCode(user.name + ':' + user.email) % someColors.length;
+  if (c < 0) { c += someColors.length; }
+  return someColors[c];
+}
+
+/**
+ * Hash a string into an integer. From https://stackoverflow.com/a/7616484/328565.
+ */
+function hashCode(str: string): number {
+  let hash: number = 0;
+  for (let i = 0; i < str.length; i++) {
+    // tslint:disable-next-line:no-bitwise
+    hash = ((hash << 5) - hash + str.charCodeAt(i)) | 0;
+  }
+  return hash;
+}
+
+// These mostly come from https://clrs.cc/
+const someColors = [
+  '#0B437D',
+  '#0074D9',
+  '#7FDBFF',
+  '#39CCCC',
+  '#16DD6D',
+  '#2ECC40',
+  '#16B378',
+  '#EFCC00',
+  '#FF851B',
+  '#FF4136',
+  '#85144b',
+  '#F012BE',
+  '#B10DC9',
+];
+
+export const cssUserImage = styled('div', `
+  position: relative;
+  text-align: center;
+  text-transform: uppercase;
+  user-select: none;
+  -moz-user-select: none;
+  color: white;
+  border-radius: 100px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+
+  &-small {
+    width: 24px;
+    height: 24px;
+    font-size: 13.5px;
+    --reduced-font-size: 12px;
+  }
+  &-medium {
+    width: 32px;
+    height: 32px;
+    font-size: 18px;
+    --reduced-font-size: 16px;
+  }
+  &-large {
+    width: 40px;
+    height: 40px;
+    font-size: 22.5px;
+    --reduced-font-size: 20px;
+  }
+
+  &-anon {
+    border: 1px solid ${colors.slate};
+    color: ${colors.slate};
+  }
+  &-anon::before {
+    content: "?"
+  }
+  &-reduced {
+    font-size: var(--reduced-font-size);
+  }
+`);
+
+const cssUserPicture = styled('img', `
+  position: absolute;
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+  background-color: white;
+  border-radius: 100px;
+  border: 1px solid white;    /* make sure edge of circle with initials is not visible */
+  box-sizing: content-box;    /* keep the border outside of the size of the image */
+`);