import type { TeamMembership } from "../services";

/**
 * WHAT A TEAM IS, IN ONE LINE UNDER ITS NAME.
 *
 * The page carried a member count, which restates the row above it: the members are listed a
 * hundred pixels down and counting them again says nothing a reader could not see. The approved
 * deck writes the subtitle as "5 members across 2 practices and your family", and the two extra
 * facts are the two that make a collaboration team worth having at all - it SPANS practices, and
 * it can hold the people who help you as well as the people who treat you.
 *
 * THE PRACTICE COUNT IS THE PRACTICES THE TEAM SPANS, NOT MEMBERSHIPS OR AFFILIATIONS. Five people at
 * one practice is one practice, and a second affiliation is not a second practice. The membership does not say which
 * practice a member joined for, so the count is the fewest practices that account for every member
 * whose practice is known, chosen greedily - teams are a handful of people.
 *
 * AND AN UNRESOLVED PRACTICE IS NOT COUNTED, which is the denial rule reaching a summary. A member
 * whose organizations could not be read has `organizationDisplays` absent - not empty - and
 * counting them would put a number on a screen that the rows underneath cannot account for. An
 * EMPTY array is a different answer and is also not counted: it is a positive statement that the
 * person belongs to no organization, which is what an outside practitioner is.
 *
 * "YOURS" IS DELIBERATELY NOT BUILT. The deck opens the line with it because the deck has a second
 * tab for teams somebody else owns; the app has nowhere to show one - the patient's list query is
 * scoped to their own partition - so "Yours" would be true of every team on the screen and would
 * separate nothing. It goes in the day the other tab does.
 */
const countSpannedPractices = (affiliations: string[][]): number => {
  let uncovered = affiliations.filter((displays) => displays.length > 0);
  let count = 0;

  while (uncovered.length > 0) {
    const reach = new Map<string, number>();
    for (const displays of uncovered) {
      for (const display of new Set(displays)) reach.set(display, (reach.get(display) ?? 0) + 1);
    }
    const [widest] = [...reach.entries()].reduce((best, entry) => (entry[1] > best[1] ? entry : best));
    uncovered = uncovered.filter((displays) => !displays.includes(widest));
    count += 1;
  }

  return count;
};

export const describeRoster = (members: TeamMembership[]): string => {
  const people = members.length;
  const affiliations: string[][] = [];
  let family = false;

  for (const member of members) {
    if (member.memberClass === "related-person") family = true;
    affiliations.push(member.organizationDisplays ?? []);
  }

  const practices = countSpannedPractices(affiliations);
  const parts = [`${people} member${people === 1 ? "" : "s"}`];
  if (practices > 0) {
    parts.push(`across ${practices} practice${practices === 1 ? "" : "s"}`);
  }
  if (family) parts.push("and your family");

  return parts.join(" ");
};

export default describeRoster;