import { pageRoute } from "../routes.js";

/* Page-alias administration view. */

class AliasAdmin {
  /**
   * goal   : Create a controller for retained page aliases.
   * pre    : api and translate are application services; reloadPages refreshes
   *          the public page and alias catalogue after an administrative edit.
   * post   : The controller is ready to load and mutate aliases.
   * result : A directly usable alias administration controller.
   */
  constructor(api, translate, reloadPages) {
    this.api = api;
    this.translate = translate;
    this.reloadPages = reloadPages;
    this.list = document.getElementById("alias-list");
    this.status = document.getElementById("alias-admin-status");
  }

  /**
   * goal   : Load retained aliases and render their references and actions.
   * pre    : The current session has administrator permission.
   * post   : The alias list represents the current server state.
   * result : A promise that resolves when all alias rows have been rendered.
   */
  async load() {
    this.status.textContent = "";
    const result = await this.api("/api/admin/aliases");
    const aliases = result.aliases || [];
    this.list.replaceChildren();

    if (aliases.length === 0) {
      const empty = document.createElement("p");
      empty.className = "muted";
      empty.textContent = this.translate("no-page-aliases", "No page aliases.");
      this.list.append(empty);
      return;
    }

    for (const alias of aliases) this.list.append(this.#renderAlias(alias));
  }

  /** Build one alias row, including cleanup and deletion actions. */
  #renderAlias(alias) {
    const row = document.createElement("article");
    row.className = "alias-row";

    const address = document.createElement("div");
    address.className = "alias-address";
    const target = document.createElement("a");
    target.href = pageRoute(alias.targetSlug);
    target.textContent = alias.targetSlug;
    address.append(
      document.createTextNode(
        `${this.translate("old-address", "Old address")}: ${alias.slug} · ` +
        `${this.translate("current-address", "Current address")}: `),
      target
    );
    row.append(address);

    const references = alias.references || [];
    const currentSummary = document.createElement("div");
    currentSummary.className = "alias-summary";
    currentSummary.textContent =
      `${this.translate("current-references", "Current references")}: ${references.length}`;
    row.append(currentSummary);

    if (references.length > 0) {
      const referenceList = document.createElement("ul");
      referenceList.className = "alias-references";
      for (const reference of references) {
        const item = document.createElement("li");
        const link = document.createElement("a");
        link.href = pageRoute(reference.slug);
        link.textContent = reference.title;
        item.append(link);
        referenceList.append(item);
      }
      row.append(referenceList);
    }

    const historicalCount = Number(alias.historicalReferenceCount || 0);
    const historicalSummary = document.createElement("div");
    historicalSummary.className = "alias-summary muted";
    historicalSummary.textContent =
      `${this.translate("historical-references", "Historical references")}: ${historicalCount}`;
    row.append(historicalSummary);

    const historicalReferences = alias.historicalReferences || [];
    if (historicalReferences.length > 0) {
      const historyList = document.createElement("ul");
      historyList.className = "alias-references alias-history";
      for (const reference of historicalReferences) {
        const item = document.createElement("li");
        item.textContent = `${reference.title} · ` +
          `${this.translate("version", "Version")} ${reference.version}`;
        historyList.append(item);
      }
      row.append(historyList);
    }

    const actions = document.createElement("div");
    actions.className = "alias-actions";
    actions.append(
      this.#cleanupButton(alias, references),
      this.#deleteButton(alias, references, historicalCount)
    );
    row.append(actions);
    return row;
  }

  /** Build the action that replaces current references to an old address. */
  #cleanupButton(alias, references) {
    const button = document.createElement("button");
    button.type = "button";
    button.textContent = this.translate("cleanup-alias", "Clean up references");
    button.disabled = references.length === 0;
    button.addEventListener("click", () => {
      this.#cleanup(alias).catch((error) => console.error(error));
    });
    return button;
  }

  /** Build the action that removes an unused alias. */
  #deleteButton(alias, references, historicalCount) {
    const button = document.createElement("button");
    button.type = "button";
    button.textContent = this.translate("delete-alias", "Delete alias");
    button.disabled = references.length > 0;
    button.addEventListener("click", () => {
      this.#delete(alias, historicalCount).catch((error) => console.error(error));
    });
    return button;
  }

  /** Confirm, perform and report reference cleanup for one alias. */
  async #cleanup(alias) {
    const question = this.translate(
      "cleanup-alias-confirm",
      "Replace all current references to this old address with the current address? Historical versions will not be changed.");
    if (!window.confirm(question)) return;
    const result = await this.api(`/api/admin/aliases/${alias.id}/cleanup`, {
      method: "POST"
    });
    await this.reloadPages();
    await this.load();
    this.status.textContent =
      `${this.translate("cleanup-complete", "Cleanup complete")}: ${result.changedPages || 0}`;
  }

  /** Confirm and remove one alias that has no current references. */
  async #delete(alias, historicalCount) {
    const warning = historicalCount > 0
      ? this.translate(
        "delete-alias-history-confirm",
        "Delete this alias? Historical page versions still contain this old address and those links may stop resolving.")
      : this.translate("delete-alias-confirm", "Delete this alias?");
    if (!window.confirm(warning)) return;
    await this.api(`/api/admin/aliases/${alias.id}`, { method: "DELETE" });
    await this.reloadPages();
    await this.load();
  }
}

export { AliasAdmin };