import { Node } from 'prosemirror-model';

/**
 * Task extraction for the task overview block (issue #154): every
 * `task_item` of a document as a flat row — its stable id (#153, null for
 * lines not yet opened in an editor), checked state, the line's text
 * (mentions and date markers excluded — they become their own columns),
 * the mentioned users (#150), and the start/due dates (#152).
 */
export interface TaskRow {
  id: string | null;
  checked: boolean;
  text: string;
  mentions: { userId: string; username: string }[];
  startDate: string | null;
  dueDate: string | null;
}

export function extractTaskRows(doc: Node): TaskRow[] {
  const rows: TaskRow[] = [];
  doc.descendants((node) => {
    if (node.type.name !== 'task_item') return;
    const row: TaskRow = {
      id: (node.attrs.id as string | null) ?? null,
      checked: node.attrs.checked === true,
      text: '',
      mentions: [],
      startDate: null,
      dueDate: null,
    };
    // The line's own content is its first paragraph; nested task lists
    // produce their own rows via the outer descendants walk.
    const paragraph = node.firstChild;
    if (paragraph && paragraph.type.name === 'paragraph') {
      paragraph.forEach((child) => {
        if (child.isText) {
          row.text += child.text ?? '';
        } else if (child.type.name === 'mention') {
          row.mentions.push({
            userId: child.attrs.userId as string,
            username: child.attrs.username as string,
          });
        } else if (child.type.name === 'date_marker') {
          if (child.attrs.kind === 'due') row.dueDate = child.attrs.date as string;
          else row.startDate = child.attrs.date as string;
        } else if (child.type.name === 'wikilink') {
          row.text +=
            (child.attrs.displayText as string | null) ?? (child.attrs.targetSlug as string);
        }
      });
    }
    row.text = row.text.replace(/\s+/g, ' ').trim();
    rows.push(row);
  });
  return rows;
}

/** Wire shapes of `GET /read/:pond/:slug/tasks` (issue #154). */
export interface TaskOverviewMention {
  id: string;
  username: string;
  displayName: string;
}

export interface TaskOverviewRow {
  /** Null for lines that never got an id — shown read-only. */
  id: string | null;
  checked: boolean;
  text: string;
  mentions: TaskOverviewMention[];
  startDate: string | null;
  dueDate: string | null;
}

export interface TaskOverviewPage {
  pageId: string;
  slug: string;
  title: string;
  tasks: TaskOverviewRow[];
}