export default function (config) {
  const tab = new TabBuilder(config);

  tab("Custom", ({ section }) => {
    section("Sample Section", ({ panel }) => {
      panel("Sample Panel", ({ panel, serie }) => {
        panel.summary = "Example full width panel";
        panel.fullWidth = true;

        serie("http_reqs[?!tags && rate]", "Request Rate");
        serie("http_req_duration[?!tags && p95]", "Request Duration p(95)");
        serie("http_req_failed[?!tags && rate ]", "Request Failed");
      });
    });
  });

  return config;
}

/**
 * The TabBuilder class implements a helper function to create a dashboard tab.
 */
class TabBuilder extends Function {
  constructor(config) {
    super();
    this.config = config;
    return new Proxy(this, { apply: (target, _, args) => target._tab(...args) });
  }

  _tab(...args) {
    const [title, summary, self, fn] = this._getargs(args, { sections: [] });

    self.title = title;
    self.summary = summary;

    if (!self.id) self.id = `tab-${this.config.tabs.length}`;

    this.currentTab = self;

    fn({ tab: self, section: (...args) => this._section(...args) });

    this.config.tabs.push(self);

    delete this.currentTab;
  }

  _section(...args) {
    const [title, summary, self, fn] = this._getargs(args, { panels: [] });

    self.title = title;
    self.summary = summary;

    if (!self.id) self.id = `${this.currentTab.id}.section-${this.currentTab.sections.length}`;

    this.currentSection = self;

    fn({ section: self, panel: (...args) => this._panel(...args) });

    this.currentTab.sections.push(self);

    delete this.currentSection;
  }

  _panel(...args) {
    const [title, kind, self, fn] = this._getargs(args, { series: [] });

    self.title = title;

    if (kind) self.kind = kind;

    if (!self.id) self.id = `${this.currentSection.id}.panel-${this.currentSection.panels.length}`;

    this.currentPanel = self;

    fn({ panel: self, serie: (...args) => this._serie(...args) });

    if (!self.kind) self.kind = "chart";

    this.currentSection.panels.push(self);

    delete this.currentPanel;
  }

  _serie(...args) {
    const [query, legend, self] = this._getargs(args, {});

    self.query = query;
    self.legend = legend;

    if (self.query == undefined) self.query = self.legend;

    this.currentPanel.series.push(self);
  }

  _getargs(args, obj) {
    const ret = [];
    let idx = 0;

    ret.push(typeof args[idx] == "string" ? args[idx++] : undefined);
    ret.push(typeof args[idx] == "string" ? args[idx++] : undefined);
    ret.push(typeof args[idx] == "object" ? Object.assign(obj, args[idx++]) : obj);
    ret.push(typeof args[idx] == "function" ? args[idx++] : () => {});

    return ret;
  }
}