<div class-rtabs {{yield extra-attributes}}>
  <div class-tab-window {{#if .direction === 'left'}}class-going-left{{else}}class-going-right{{/if}}>
    <div class-tabs>
      <div class="left-tabs">
        {{#each .tabs}}{{#unless .right}}{{>tab}}{{/unless}}{{/each}}
      </div>
      <div class="right-tabs">
        {{#each .tabs}}{{#if .right}}{{>tab}}{{/if}}{{/each}}
      </div>
      <div class="selection-indicator" style-left="{{.selectedLeft}}px" {{#if .selectedRight !== undefined}}style-right="{{.selectedRight}}px"{{/if}} />
      </div>
  </div>
  <div class-content-window
    {{#if .transition === 'fade'}}
      style-opacity="{{opacity}}"
      class-trans-fade
    {{elseif .transition === 'slide'}}
      class-trans-slide
    {{/if}}
  >
    <div class-contents style-left="{{.selectedContent * -100}}%">
      {{#each .tabs}}{{>tab-content}}{{/each}}
    </div>
  </div>
</div>

<template id="tab">
  <div
    class-tab
    {{#unless .button}}class-selected="~/selected === @index"{{/unless}}

    {{#if .disabled}}class-disabled
    {{elseif !.button}}on-click=['select', @index]{{/if}}
    as-registered="@index"
    {{#if .extraTab}}{{yield .extraTab}}{{/if}}
  >
    {{#if typeof .title === 'string'}}{{title}}{{elseif .title}}{{yield .title}}{{/if}}
    {{#if .closable && !.button}}<div class-close on-click=['close', @index]>&times;</div>{{/if}}
  </div>
</template>

<template id="tab-content">
  {{#if !.button}}
    <div
      class-tab
      class-selected="~/selectedContent === @index"
      {{#if .extra}}{{yield .extra}}{{/if}}
    >
      {{yield .template}}
    </div>
  {{else}}<div class-tab />
  {{/if}}
</template>

<script>
  import Ractive from 'ractive';

  let resizer;
  const instances = [];

  class Tabs extends Ractive {
    constructor(opts) {
      super(opts);
    }

    updateIndicator() {
      const node = this._tabs[this.get('selected')];

      if (node) {
        const start = this.get('selectedLeft');
        if (start === undefined) {
          this.set({
            selectedLeft: node.offsetLeft,
            selectedRight: node.offsetParent.clientWidth - (node.offsetLeft + node.offsetWidth)
          });
        } else {
          const max = node.offsetParent.clientWidth;
          const left = node.offsetLeft, width = node.clientWidth, right = max - left - width;

          this.set({
            direction: left < start ? 'left' : 'right',
            selectedLeft: left,
            selectedRight: right
          });
        }
      } else {
        this.set({
          selectedLeft: 0,
          selectedRight: this.find('.tabs').offsetWidth
        });
      }
    }
  }

  const tabAttrs = ['closable', 'disabled', 'title', 'right', 'button'];

  Ractive.extendWith(Tabs, {
    template: $TEMPLATE,
    cssId: 'tabs',
    noCssTransform: true,
    css: $CSS,
    attributes: ['transition'],
    data() {
      return {
        tabs: [],
        rightTabs: [],
        selected: 0,
        selectedContent: 0,
        opacity: 1
      }
    },
    on: {
      config() {
        const tpl = this.partials.content;
        if (tpl) {
          const tabs = tpl.filter(n => n.e === 'tab').map(t => {
            const tab = {
              template: { t: t.f }
            };
            const extra = [];
            const extraTab = [];

            t.m.forEach(a => {
              if (a.t === 13 && ~tabAttrs.indexOf(a.n)) tab[a.n] = a.f === 0 ? true : typeof a.f === 'string' ? a.f : { t: a.f };
              else if (a.t === 70) extraTab.push(a);
              else extra.push(a);
            });

            if (extra.length) tab.extra = { t: extra };
            if (extraTab.length) tab.extraTab = { t: extraTab };

            return tab;
          });

          tabs.unshift('tabs');
          this.push.apply(this, tabs);

          if (!resizer && typeof window !== undefined) {
            resizer = true;
            window.addEventListener('resize', () => {
              instances.forEach(i => i.updateIndicator());
            });
          }

          instances.push(this);
          }
      },
      select(ctx, idx) {
        const current = this.get('selected');
        const prs = [];
        const node = this.find('.contents');
        const trans = this.get('transition');

        if (current !== idx) {
          if (trans === 'fade') {
            this.set({
              opacity: 0,
              selected: idx
            });
            this.updateIndicator();

            setTimeout(() => {
              this.set({
                selectedContent: idx,
                opacity: 1
              });
            }, 300);
          } else if (trans === 'slide') {
            this.set('selected', idx);
            this.set('selectedContent', idx);
            this.updateIndicator();
          } else {
            this.set({
              selected: idx,
              selectedContent: idx
            });
            this.updateIndicator();
          }
        }
      },
      close(ctx, idx) {
        const tab = this.getContext(this._tabs[idx]);
        let ok = true;

        if (tab.element.events.find(e => e.events.find(e => e.name === 'close'))) {
          ok = tab.raise('close');
        }

        if (ok) this.splice('tabs', idx, 1);

        return false;
      },
      teardown() {
        instances.splice(instances.indexOf(this), 1);
      }
    },
    decorators: {
      registered(node, idx) {
        const me = this;

        if (!this._tabs) this._tabs = [];

        this._tabs[idx] = node;
        this.updateIndicator();

        return {
          teardown() {},
          invalidate() {
            me.updateIndicator();
          },
          update(idx) {
            me._tabs[idx] = node;
            setTimeout(() => me.updateIndicator());
          }
        };
      }
    }
  });

  export default Tabs;
</script>

<style>
  .rtabs {
    position: relative;
  }

  .rtabs > .tab-window {
    overflow-y: hidden;
    overflow-x: auto;
    box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.14),
      0 1px 5px 0 rgba(0, 0, 0, 0.12),
      0 3px 1px -2px rgba(0, 0, 0, 0.2);
  }

  .rtabs > .tab-window .tabs {
    display: table;
    position: relative;
    min-width: 100%;
    overflow-x: auto;
    overflow-y: hidden;
    white-space: nowrap;
  }

  .rtabs > .tab-window .tab {
    display: inline-block;
    box-sizing: border-box;
    padding: 0.5em 1em;
    height: 2.5em;
    cursor: pointer;
    opacity: 0.7;
    transition: opacity 0.2s ease-in-out;
    user-select: none;
  }
  .rtabs > .tab-window .tab:hover {
    opacity: 1;
  }

  .rtabs > .tab-window .tab.selected {
    opacity: 1;
  }

  .rtabs > .tab-window .tab.disabled {
    opacity: 0.4;
  }

  .rtabs > .tab-window .right-tabs {
    text-align: right;
    display: table-cell;
  }

  .rtabs > .tab-window .left-tabs {
    text-align: left;
    display: table-cell;
  }

  .rtabs > .tab-window .tab > .close {
    display: inline-block;
    margin-right: -0.5em;
    font-weight: 700;
  }

  .rtabs > .tab-window .selection-indicator {
    position: absolute;
    bottom: 0;
    height: 2px;
    background-color: blue;
  }
  .rtabs > .tab-window.going-left .selection-indicator {
    transition: left 0.2s ease-in-out, right 0.2s ease-in-out 0.1s;
  }
  .rtabs > .tab-window.going-right .selection-indicator {
    transition: left 0.2s ease-in-out 0.1s, right 0.2s ease-in-out;
  }

  .rtabs > .content-window {
    width: 100%;
    overflow: hidden;
  }

  .rtabs > .content-window > .contents {
    list-style: none;
    padding: 0;
    margin: 0;
    position: relative;
    white-space: nowrap;
    left: 0;
  }
  .rtabs > .content-window.trans-slide > .contents {
    transition: left 0.45s ease-in-out;
  }
  .rtabs > .content-window.trans-fade {
    transition: opacity 0.3s ease;
  }

  .rtabs > .content-window > .contents > .tab {
    display: inline-block;
    width: 100%;
    vertical-align: top;
    white-space: initial;
    transition: opacity 0.1s ease-in-out;
  }
</style>