Add ability to specify alternative text for media attachments (#5123)

* Fix #117 - Add ability to specify alternative text for media attachments

- POST /api/v1/media accepts `description` straight away
- PUT /api/v1/media/:id to update `description` (only for unattached ones)
- Serialized as `name` of Document object in ActivityPub
- Uploads form adjusted for better performance and description input

* Add tests

* Change undo button blend mode to difference

1 files changed, 96 insertions, 0 deletions

diff --git a/app/javascript/mastodon/features/compose/components/upload.js b/app/javascript/mastodon/features/compose/components/upload.js
new file mode 100644
index 000000000..c2bf3b72e
--- /dev/null
+++ b/app/javascript/mastodon/features/compose/components/upload.js
@@ -0,0 +1,96 @@
+import React from 'react';
+import ImmutablePropTypes from 'react-immutable-proptypes';
+import PropTypes from 'prop-types';
+import IconButton from '../../../components/icon_button';
+import Motion from 'react-motion/lib/Motion';
+import spring from 'react-motion/lib/spring';
+import ImmutablePureComponent from 'react-immutable-pure-component';
+import { defineMessages, injectIntl } from 'react-intl';
+import classNames from 'classnames';
+
+const messages = defineMessages({
+  undo: { id: 'upload_form.undo', defaultMessage: 'Undo' },
+  description: { id: 'upload_form.description', defaultMessage: 'Describe for the visually impaired' },
+});
+
+@injectIntl
+export default class Upload extends ImmutablePureComponent {
+
+  static propTypes = {
+    media: ImmutablePropTypes.map.isRequired,
+    intl: PropTypes.object.isRequired,
+    onUndo: PropTypes.func.isRequired,
+    onDescriptionChange: PropTypes.func.isRequired,
+  };
+
+  state = {
+    hovered: false,
+    focused: false,
+    dirtyDescription: null,
+  };
+
+  handleUndoClick = () => {
+    this.props.onUndo(this.props.media.get('id'));
+  }
+
+  handleInputChange = e => {
+    this.setState({ dirtyDescription: e.target.value });
+  }
+
+  handleMouseEnter = () => {
+    this.setState({ hovered: true });
+  }
+
+  handleMouseLeave = () => {
+    this.setState({ hovered: false });
+  }
+
+  handleInputFocus = () => {
+    this.setState({ focused: true });
+  }
+
+  handleInputBlur = () => {
+    const { dirtyDescription } = this.state;
+
+    this.setState({ focused: false, dirtyDescription: null });
+
+    if (dirtyDescription !== null) {
+      this.props.onDescriptionChange(this.props.media.get('id'), dirtyDescription);
+    }
+  }
+
+  render () {
+    const { intl, media } = this.props;
+    const active          = this.state.hovered || this.state.focused;
+    const description     = this.state.dirtyDescription || media.get('description') || '';
+
+    return (
+      <div className='compose-form__upload' onMouseEnter={this.handleMouseEnter} onMouseLeave={this.handleMouseLeave}>
+        <Motion defaultStyle={{ scale: 0.8 }} style={{ scale: spring(1, { stiffness: 180, damping: 12 }) }}>
+          {({ scale }) => (
+            <div className='compose-form__upload-thumbnail' style={{ transform: `translateZ(0) scale(${scale})`, backgroundImage: `url(${media.get('preview_url')})` }}>
+              <IconButton icon='times' title={intl.formatMessage(messages.undo)} size={36} onClick={this.handleUndoClick} />
+
+              <div className={classNames('compose-form__upload-description', { active })}>
+                <label>
+                  <span style={{ display: 'none' }}>{intl.formatMessage(messages.description)}</span>
+
+                  <input
+                    placeholder={intl.formatMessage(messages.description)}
+                    type='text'
+                    value={description}
+                    maxLength={140}
+                    onFocus={this.handleInputFocus}
+                    onChange={this.handleInputChange}
+                    onBlur={this.handleInputBlur}
+                  />
+                </label>
+              </div>
+            </div>
+          )}
+        </Motion>
+      </div>
+    );
+  }
+
+}