'use strict';

class TagSlice {
  constructor(container) {
    this.buildDom_(container);
    addEventListener('hashchange', () => this.parseUrl_());
    this.parseUrl_();
    this.loadJson_();
    this.registerKeys_();
  }

  registerKeys_() {
    document.addEventListener('keypress', (e) => {
      switch (e.key) {
        case 'c':
          this.downloadCsv_();
          break;

        case 'r':
          this.loadJson_();
          break;

        case 'x':
          this.tagList_.classList.toggle('expandAll');
          break;
      }
    });
  }

  createElement_(container, tagName, text) {
    let elem = document.createElement(tagName);
    container.appendChild(elem);
    if (text) {
      elem.innerText = text;
    }
    return elem;
  }

  createTag_(container, tagName) {
    let elem = this.createElement_(container, 'tag');
    this.createElement_(elem, 'tagName', tagName);
    return elem;
  }

  createCard_(container, object) {
    let elem = this.createElement_(container, 'card');
    let title = this.createElement_(elem, 'cardTitle', object['title']);
    title.addEventListener('click', () => {
      elem.classList.toggle('expanded');
    });
    let detail = this.createElement_(elem, 'cardDetail');
    for (let sectionName in object['content']) {
      let section = this.createElement_(detail, 'cardSection');
      if (sectionName) {
        this.createElement_(section, 'cardSectionTitle', sectionName);
      }
      this.createElement_(section, 'cardSectionText', object['content'][sectionName]);
    }
    if (object['references']) {
      let refList = this.createElement_(detail, 'referenceList');
      for (let refName in object['references']) {
        let ref = this.createElement_(refList, 'a', refName);
        ref.href = object['references'][refName];
      }
    }
  }

  parseUrl_() {
    this.tags_ = [];
    let hash = window.location.hash.substr(1);
    if (hash) {
      for (let tag of hash.split(',')) {
        this.tags_.push(decodeURIComponent(tag));
      }
    }
    let query = window.location.href.split('?', 2)[1];
    if (query) {
      query = query.split('#', 1)[0];
      for (let tag of query.split(',')) {
        this.tags_.push(decodeURIComponent(tag));
      }
    }
    document.title = this.tags_.join(', ');
    this.maybeRender_();
  }

  buildDom_(container) {
    this.tagList_ = this.createElement_(container, 'tagList');
  }

  loadJson_() {
    let xhr = new XMLHttpRequest();
    xhr.open('GET', 'tagslice.json');
    xhr.responseType = 'json';
    xhr.onload = () => {
      this.onJsonLoad_(xhr.response);
    };
    xhr.send();
  }

  onJsonLoad_(response) {
    this.objects_ = response;
    this.maybeRender_();
  }

  maybeRender_() {
    if (!this.tags_ || !this.objects_) {
      return;
    }
    this.tagList_.innerHTML = '';
    for (let tag of this.tags_) {
      let elem = this.createTag_(this.tagList_, tag);
      for (let object of this.objects_) {
        if (!object['tags'].includes(tag)) {
          continue;
        }
        this.createCard_(elem, object);
      }
    }
  }

  downloadCsv_() {
    this.download_('text/csv', document.title + '.csv', this.buildCsvString_());
  }

  buildCsvString_() {
    let rowsEncoded = [];
    for (let row of this.buildCsv_()) {
      let cellsEncoded = [];
      for (let cell of row) {
        cellsEncoded.push(this.escapeCsv_(cell));
      }
      rowsEncoded.push(cellsEncoded.join(','));
    }
    return rowsEncoded.join('\r\n');
  }

  buildCsv_() {
    let header = ['Tag', 'Title'];
    let keys = this.contentKeys_();
    for (let key of keys) {
      if (key == '') {
        header.push('Description');
      } else {
        header.push(key);
      }
    }
    let rows = [header];
    for (let tag of this.tags_) {
      for (let object of this.objects_) {
        if (!object['tags'].includes(tag)) {
          continue;
        }
        let row = [tag, object['title']];
        for (let key of keys) {
          row.push(object['content'][key] || '');
        }
        rows.push(row);
      }
    }
    return rows;
  }

  escapeCsv_(value) {
    return '"' + value.replace(/"/g, '""') + '"';
  }

  contentKeys_() {
    let ret = new Set();
    for (let tag of this.tags_) {
      for (let object of this.objects_) {
        if (!object['tags'].includes(tag)) {
          continue;
        }
        for (let key in object['content']) {
          ret.add(key);
        }
      }
    }
    return ret;
  }

  download_(mime, filename, content) {
    let a = document.createElement('a');
    a.download = filename;
    a.href = 'data:' + mime + ';base64,' + btoa(content);
    a.click();
  }
}