import type { ConversationSummary, DateGroup } from "./types";

export function groupByDate(conversations: ConversationSummary[]): DateGroup[] {
  const now = new Date();
  const today = new Date(now.getFullYear(), now.getMonth(), now.getDate());
  const yesterday = new Date(today.getTime() - 86400000);
  const lastWeek = new Date(today.getTime() - 7 * 86400000);
  const lastMonth = new Date(today.getTime() - 30 * 86400000);

  const groups: Map<string, ConversationSummary[]> = new Map([
    ["Today", []],
    ["Yesterday", []],
    ["Last 7 days", []],
    ["Last 30 days", []],
    ["Older", []],
  ]);

  for (const conv of conversations) {
    const date = new Date(conv.createdAt);
    const label =
      date >= today
        ? "Today"
        : date >= yesterday
          ? "Yesterday"
          : date >= lastWeek
            ? "Last 7 days"
            : date >= lastMonth
              ? "Last 30 days"
              : "Older";

    groups.get(label)!.push(conv);
  }

  return Array.from(groups.entries())
    .filter(([, items]) => items.length > 0)
    .map(([label, items]) => ({ label, conversations: items }));
}