import type { ChangelogSection, ChangelogSectionTitle } from "@/lib/changelog-types";

/** Use a short paragraph when a release has very few notes. */
const PARAGRAPH_ITEM_THRESHOLD = 4;

export function stripChangelogMarkdown(text: string): string {
  return text
    .replace(/`([^`]+)`/g, "$1")
    .replace(/\*\*([^*]+)\*\*/g, "$1")
    .replace(/\s+/g, " ")
    .trim();
}

export function countReleaseItems(sections: ChangelogSection[]): number {
  return sections.reduce((total, section) => total + section.items.length, 0);
}

export function shouldUseParagraphSummary(sections: ChangelogSection[]): boolean {
  return countReleaseItems(sections) <= PARAGRAPH_ITEM_THRESHOLD;
}

const SECTION_VERBS: Partial<Record<ChangelogSectionTitle, string>> = {
  Added: "introduces",
  Changed: "improves",
  Fixed: "fixes",
  Removed: "removes",
  Deprecated: "deprecates",
  Security: "patches",
};

function joinNaturalList(items: string[]): string {
  if (items.length === 0) return "";
  if (items.length === 1) return items[0];
  if (items.length === 2) return `${items[0]} and ${items[1]}`;
  return `${items.slice(0, -1).join(", ")}, and ${items[items.length - 1]}`;
}

export function buildReleaseParagraph(sections: ChangelogSection[]): string {
  const clauses = sections
    .map((section) => {
      const items = section.items.map((item) =>
        stripChangelogMarkdown(item).replace(/\.$/, "").toLowerCase()
      );
      const verb = SECTION_VERBS[section.title] ?? "updates";
      return `${verb} ${joinNaturalList(items)}`;
    })
    .filter(Boolean);

  if (clauses.length === 0) return "";
  if (clauses.length === 1) {
    return `This release ${clauses[0]}.`;
  }

  const last = clauses[clauses.length - 1];
  const rest = clauses.slice(0, -1);
  return `This release ${rest.join(", ")}, and ${last}.`;
}

function toLatinDigits(value: string): string {
  return value.replace(/[\u0660-\u0669\u06f0-\u06f9]/g, (digit) =>
    String(
      digit.charCodeAt(0) -
        (digit <= "\u0669" ? 0x0660 : 0x06f0)
    )
  );
}

export function formatReleaseDate(date: string): string {
  const parsed = new Date(`${date}T00:00:00`);
  if (Number.isNaN(parsed.getTime())) return date;

  const formatted = new Intl.DateTimeFormat("en-US", {
    month: "long",
    day: "numeric",
    year: "numeric",
    numberingSystem: "latn",
  }).format(parsed);

  return toLatinDigits(formatted);
}