Initial Commit Rework

frontend/src/Components/Page/PageJumpBar.js

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+import _ from 'lodash';
+import PropTypes from 'prop-types';
+import React, { Component } from 'react';
+import Measure from 'react-measure';
+import dimensions from 'Styles/Variables/dimensions';
+import PageJumpBarItem from './PageJumpBarItem';
+import styles from './PageJumpBar.css';
+
+const ITEM_HEIGHT = parseInt(dimensions.jumpBarItemHeight);
+
+class PageJumpBar extends Component {
+
+  //
+  // Lifecycle
+
+  constructor(props, context) {
+    super(props, context);
+
+    this.state = {
+      height: 0,
+      visibleItems: props.items
+    };
+  }
+
+  componentDidMount() {
+    this.computeVisibleItems();
+  }
+
+  componentDidUpdate(prevProps, prevState) {
+    if (
+      prevProps.items !== this.props.items ||
+      prevState.height !== this.state.height
+    ) {
+      this.computeVisibleItems();
+    }
+  }
+
+  //
+  // Control
+
+  computeVisibleItems() {
+    const {
+      items,
+      minimumItems
+    } = this.props;
+
+    const height = this.state.height;
+    const maximumItems = Math.floor(height / ITEM_HEIGHT);
+    const diff = items.length - maximumItems;
+
+    if (diff < 0) {
+      this.setState({ visibleItems: items });
+      return;
+    }
+
+    if (items.length < minimumItems) {
+      this.setState({ visibleItems: items });
+      return;
+    }
+
+    const removeDiff = Math.ceil(items.length / maximumItems);
+
+    const visibleItems = _.reduce(items, (acc, item, index) => {
+      if (index % removeDiff === 0) {
+        acc.push(item);
+      }
+
+      return acc;
+    }, []);
+
+    this.setState({ visibleItems });
+  }
+
+  //
+  // Listeners
+
+  onMeasure = ({ height }) => {
+    this.setState({ height });
+  }
+
+  //
+  // Render
+
+  render() {
+    const {
+      minimumItems,
+      onItemPress
+    } = this.props;
+
+    const {
+      visibleItems
+    } = this.state;
+
+    if (!visibleItems.length || visibleItems.length < minimumItems) {
+      return null;
+    }
+
+    return (
+      <div className={styles.jumpBar}>
+        <Measure
+          whitelist={['height']}
+          onMeasure={this.onMeasure}
+        >
+          <div className={styles.jumpBarItems}>
+            {
+              visibleItems.map((item) => {
+                return (
+                  <PageJumpBarItem
+                    key={item}
+                    label={item}
+                    onItemPress={onItemPress}
+                  />
+                );
+              })
+            }
+          </div>
+        </Measure>
+      </div>
+    );
+  }
+}
+
+PageJumpBar.propTypes = {
+  items: PropTypes.arrayOf(PropTypes.string).isRequired,
+  minimumItems: PropTypes.number.isRequired,
+  onItemPress: PropTypes.func.isRequired
+};
+
+PageJumpBar.defaultProps = {
+  minimumItems: 5
+};
+
+export default PageJumpBar;