Gallery app with Finite State Machines (xstate)

gallery-app-with-finite-state-machines-xstate.markdown

Gallery app with Finite State Machines (xstate)

A Pen by Mihai on CodePen.

License.

index.html

<div id="app"></div>

script.babel

const { Machine } = xstate;

const galleryMachine = Machine({
  initial: 'start',
  states: {
    start: {
      on: {
        SEARCH: 'loading'
      }
    },
    loading: {
      onEntry: ['search'],
      on: {
        SEARCH_SUCCESS: {
          gallery: {
            actions: ['updateItems']
          }
        },
        SEARCH_FAILURE: 'error',
        CANCEL_SEARCH: 'gallery'
      }
    },
    error: {
      on: {
        SEARCH: 'loading'
      }
    },
    gallery: {
      on: {
        SEARCH: 'loading',
        SELECT_PHOTO: 'photo'
      }
    },
    photo: {
      onEntry: ['setPhoto'],
      on: {
        EXIT_PHOTO: 'gallery'
      }
    }
  }
});

class App extends React.Component {
  constructor() {
    super();
    
    this.state = {
      gallery: galleryMachine.initialState,
      query: '',
      items: []
    };
  }
  
  command(action, event) {
    switch (action) {
      case 'search':
        // execute the search command
        this.search(event.query);
        break;
      case 'updateItems':
        if (event.items) {
          // update the state with the found items
          return { items: event.items };
        }
        break;
      case 'setPhoto':
        if (event.item) {
          return { photo: event.item }
        }
      default:
        break;
    }
  }
  
  transition(event) {
    const currentGalleryState = this.state.gallery;
    const nextGalleryState =
      galleryMachine.transition(currentGalleryState, event.type);
    
    if (nextGalleryState.actions) {
      const nextState = nextGalleryState.actions
        .reduce((state, action) => this.command(action, event) || state, undefined);
      
      this.setState({
        gallery: nextGalleryState.value,
        ...nextState
      });
    }
  }
  
  handleSubmit(e) {
    e.persist();
    e.preventDefault();
    
    this.transition({ type: 'SEARCH', query: this.state.query });
  }
  
  search(query) {
    const encodedQuery = encodeURIComponent(query);
    
    setTimeout(() => {      
      fetchJsonp(
        `https://api.flickr.com/services/feeds/photos_public.gne?lang=en-us&format=json&tags=${encodedQuery}`,
        { jsonpCallback: 'jsoncallback' })
        .then(res => res.json())
        .then(data => {
          this.transition({ type: 'SEARCH_SUCCESS', items: data.items });
        })
        .catch(error => {
          this.transition({ type: 'SEARCH_FAILURE' });
        });
    }, 1000);
  }
  handleChangeQuery(value) {
    this.setState({ query: value })
  }
  renderForm(state) {
    const searchText = {
      loading: 'Searching...',
      error: 'Try search again',
      start: 'Search'
    }[state] || 'Search';
    
    return (
      <form className="ui-form" onSubmit={e => this.handleSubmit(e)}>
        <input
          type="search"
          className="ui-input"
          value={this.state.query}
          onChange={e => this.handleChangeQuery(e.target.value)}
          placeholder="Search Flickr for photos..."
          disabled={state === 'loading'}
        />
        <div className="ui-buttons">
          <button
            className="ui-button"
            disabled={state === 'loading'}>
              {searchText}
          </button>
          {state === 'loading' &&
            <button
              className="ui-button"
              type="button"
              onClick={() => this.transition({ type: 'CANCEL_SEARCH' })}>
              Cancel
            </button>
          }
        </div>
      </form>
    );
  }
  renderGallery(state) {
    return (
      <section className="ui-items" data-state={state}>
        {state === 'error'
          ? <span className="ui-error">Uh oh, search failed.</span>
          : this.state.items.map((item, i) =>
            <img
              src={item.media.m}
              className="ui-item"
              style={{'--i': i}}
              key={item.link}
              onClick={() => this.transition({
                type: 'SELECT_PHOTO', item
              })}
            />
          )
        }
      </section>
    );
  }
  renderPhoto(state) {
    if (state !== 'photo') return;
    
    return (
      <section
        className="ui-photo-detail"
        onClick={() => this.transition({ type: 'EXIT_PHOTO' })}>
        <img src={this.state.photo.media.m} className="ui-photo"/>
      </section>
    )
  }
  render() {
    const galleryState = this.state.gallery;
    
    return (
      <div className="ui-app" data-state={galleryState}>
        {this.renderForm(galleryState)}
        {this.renderGallery(galleryState)}
        {this.renderPhoto(galleryState)}
      </div>
    );
  }
}

ReactDOM.render(<App />, document.querySelector('#app'));

scripts

<script src="https://unpkg.com/react@16.0.0/umd/react.production.min.js"></script>
<script src="https://unpkg.com/react-dom@16.0.0/umd/react-dom.production.min.js"></script>
<script src="https://unpkg.com/fetch-jsonp@1.1.3/build/fetch-jsonp.js"></script>
<script src="https://unpkg.com/xstate@3.0.1/dist/xstate.js"></script>

style.scss

*, *:before, *:after {
  position: relative;
  box-sizing: border-box;
}

html, body {
  height: 100%;
  width: 100%;
  padding: 0;
  margin: 0;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #FAFAFA;
}

@mixin shadow($color: rgba(black, 0.1)) {
  box-shadow: 0 .2rem 1rem $color;
}

* {
  transition: all .3s cubic-bezier(.2, 0, .4, 1);
}

.ui-app {
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  width: 40rem;
  max-width: 90vw;
  height: calc(100vh - 2rem);
  
  &[data-state="start"] {
    justify-content: center;
  }
  
  &[data-state="loading"] {
    .ui-item {
      opacity: .5;
    }
  }
  
  &[data-state="photo"] {
    * {
      opacity: 0.3;
    }
    
    .ui-photo-detail, .ui-photo-detail * {
      opacity: 1;
    }
    
    .ui-items {
      pointer-events: none;
    }
  }
  
  &:after {
    content: 'current state: ' attr(data-state);
    position: absolute;
    bottom: .5rem;
    color: white;
    background-color: rgba(black, 0.4);
    font-size: 1rem;
    padding: .5rem 1rem;
    border-radius: 1rem;
    left: 50%;
    transform: translateX(-50%);
    text-shadow: 0 0 .1rem black;
    pointer-events: none;
  }
}

.ui-form {
  margin-bottom: 1rem;
}

.ui-input {
  @include shadow();
  display: block;
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  border: none;
  font-size: 2rem;
  height: 3rem;
  margin-bottom: 1rem;
  padding: 0 1rem;
  
  &::-webkit-input-placeholder {
    color: #CDCDCD;
  }
  
  &:focus {
    outline: none;
  }
}

.ui-buttons {
  text-align: center;
}

.ui-button {
  @include shadow();
  display: inline-block;
  -webkit-appearance: none;
  appearance: none;
  border: none;
  background-color: #EB7452;
  color: white;
  height: 3rem;
  padding: 0 3rem;
  border-radius: 3rem;
  margin: 0 1rem;
  
  &[disabled] {
    opacity: 0.5;
  }
  
  &[type="button"] {
    background-color: #555;
  }
}

.ui-items {
  display: flex;
  flex-wrap: wrap;
  flex-direction: row;
  justify-content: center;
  flex-shrink: 1;
  overflow-y: scroll;
  margin: 0 -.25rem;
  
  &:hover > .ui-item {
    opacity: 0.7;
    
    &:hover {
      opacity: 1;
    }
  }
}

.ui-item {
  display: block;
  height: 10rem;
  width: auto;
  flex-shrink: 0;
  flex-grow: 0;
  margin: .25rem;
  animation: item .5s calc(var(--i, 0) * .05s) cubic-bezier(.5, 0, .2, 1) both;
  background-color: #EEE;
  
  @keyframes item {
    from {
      transform: scale(0);
    }
    to {
      transform: scale(1);
    }
  }
}

.ui-photo-detail {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.ui-photo {
  height: auto;
  width: auto;
  min-height: 50vh;
  min-width: 50vw;
  max-height: 100%;
  max-width: 100%;
}