// retoor <retoor@molodetz.nl>
import { Poller } from "./Poller.js";

export class LocalTime {
  constructor() {
    this.dateFormat = new Intl.DateTimeFormat("en-GB", { day: "2-digit", month: "2-digit", year: "numeric" });
    this.timeFormat = new Intl.DateTimeFormat("en-GB", { hour: "2-digit", minute: "2-digit" });
    this.fullFormat = new Intl.DateTimeFormat("en-GB", { dateStyle: "full", timeStyle: "long" });
    this.relative = new Intl.RelativeTimeFormat("en-GB", { numeric: "auto" });
    this.renderAll(document);
    this.observer = new MutationObserver((mutations) => {
      mutations.forEach((mutation) => mutation.addedNodes.forEach((node) => node.nodeType === 1 && this.renderAll(node)));
    });
    this.observer.observe(document.body, { childList: true, subtree: true });
    this.poller = new Poller(() => this.renderAll(document, "ago"), 60000, { pauseHidden: true }).start();
  }

  renderAll(root, onlyMode = null) {
    const nodes = root.matches?.("time[data-dt]") ? [root] : root.querySelectorAll("time[data-dt]");
    nodes.forEach((node) => {
      if (!onlyMode || node.dataset.mode === onlyMode) {
        this.render(node);
      }
    });
  }

  render(node) {
    const date = new Date(node.dataset.dt);
    if (Number.isNaN(date.getTime())) {
      return;
    }
    const mode = node.dataset.mode || "datetime";
    node.title = this.fullFormat.format(date);
    if (mode === "date") {
      node.textContent = this.dateFormat.format(date).replaceAll("-", "/");
    } else if (mode === "time") {
      node.textContent = this.timeFormat.format(date);
    } else if (mode === "ago") {
      node.textContent = this.ago(date);
    } else {
      node.textContent = `${this.dateFormat.format(date).replaceAll("-", "/")} ${this.timeFormat.format(date)}`;
    }
  }

  ago(date) {
    const seconds = Math.round((date.getTime() - Date.now()) / 1000);
    const steps = [["year", 31536000], ["month", 2592000], ["day", 86400], ["hour", 3600], ["minute", 60]];
    for (const [unit, size] of steps) {
      if (Math.abs(seconds) >= size) {
        return this.relative.format(Math.round(seconds / size), unit);
      }
    }
    return this.relative.format(seconds, "second");
  }
}