/**
 * Present and maintain the stored history of one CMap.
 *
 * History records come from CmapRepository. Loading a version is delegated to
 * the workspace because it controls unsaved-change transitions and the editor.
 */
export class CmapHistoryDialog {
  constructor(dialog, repository, tr, pageDisplayDate, can, loadVersion, showStatus) {
    this.dialog = dialog;
    this.repository = repository;
    this.tr = tr;
    this.pageDisplayDate = pageDisplayDate;
    this.can = can;
    this.loadVersion = loadVersion;
    this.showStatus = showStatus;
    this.list = dialog.querySelector("#cmap-history-list");

    dialog.querySelector("#cmap-history-close").addEventListener("click", () => dialog.close());
  }

  async open(conceptMap) {
    const versions = await this.repository.history(conceptMap);
    this.list.replaceChildren();
    if (!versions.length) this.showEmptyMessage();
    for (const version of versions) this.list.append(this.versionRow(conceptMap, version));
    this.dialog.showModal();
  }

  showEmptyMessage() {
    const empty = document.createElement("p");
    empty.className = "muted cmap-history-empty";
    empty.textContent = this.tr(
      "no-concept-map-history", "No snapshots or manual saves yet.");
    this.list.append(empty);
  }

  versionRow(conceptMap, version) {
    const row = document.createElement("div");
    row.className = "cmap-history-row";
    const label = document.createElement("div");
    const heading = document.createElement("strong");
    heading.textContent = `${this.tr("version", "Version")} ${version.version} — ${version.title}`;
    const meta = document.createElement("div");
    meta.className = "muted";
    meta.textContent = `${this.pageDisplayDate(version.createdAt)} · ${version.author} · ${this.versionSummary(version)}`;
    label.append(heading, document.createElement("br"), meta);

    const actions = document.createElement("div");
    actions.className = "cmap-history-actions";
    actions.append(this.loadButton(conceptMap, version));
    if (this.can("editor")) actions.append(this.deleteButton(conceptMap, version, row));
    row.append(label, actions);
    return row;
  }

  versionSummary(version) {
    const knownSummaries = {
      create: this.tr("concept-map-created-version", "CMap created"),
      rename: this.tr("concept-map-renamed-version", "CMap renamed")
    };
    let summary = knownSummaries[version.action] || version.summary;
    if (version.action === "snapshot") {
      const snapshotLabel = this.tr("snapshot", "Snapshot");
      if (version.summary === "Current state when CMap history was enabled") {
        summary = this.tr("concept-map-initial-version", "Initial available version");
      } else {
        summary = version.summary === snapshotLabel ?
          snapshotLabel : `${snapshotLabel} — ${version.summary}`;
      }
    }
    if (version.summary === "Automatic save") {
      summary = this.tr("automatic-save", "Automatic save");
    }
    if (version.summary === "Manual save") summary = this.tr("manual-save", "Manual save");
    return summary;
  }

  loadButton(conceptMap, version) {
    const load = document.createElement("button");
    load.type = "button";
    load.textContent = version.version === conceptMap.currentVersion ?
      this.tr("current-version", "Current") : this.tr("load-version", "Load version");
    load.disabled = version.version === conceptMap.currentVersion;
    load.addEventListener("click", () => {
      this.dialog.close();
      this.loadVersion(version.version);
    });
    return load;
  }

  deleteButton(conceptMap, version, row) {
    const remove = document.createElement("button");
    remove.type = "button";
    remove.textContent = this.tr("delete-history-item", "Delete");
    remove.addEventListener("click", async () => {
      const question = this.tr(
        "delete-concept-map-history-confirm",
        "Delete CMap history version {version}? The current CMap will not be changed.")
        .replace("{version}", String(version.version));
      if (!window.confirm(question)) return;
      remove.disabled = true;
      try {
        await this.repository.deleteVersion(conceptMap, version.version);
        row.remove();
        if (!this.list.querySelector(".cmap-history-row")) this.showEmptyMessage();
        this.showStatus(
          this.tr("concept-map-history-deleted", "History item deleted"), true);
      } catch (error) {
        remove.disabled = false;
        this.showStatus(error.message);
      }
    });
    return remove;
  }
}