/** Weights applied to each component of the unified AI Readiness score. */
export const SCORE_WEIGHTS = {
  visibility: 0.45,
  catalog: 0.45,
  agent: 0.1,
} as const;

const GRADE_BANDS: Array<{ min: number; grade: string }> = [
  { min: 80, grade: 'A' },
  { min: 65, grade: 'B' },
  { min: 50, grade: 'C' },
  { min: 35, grade: 'D' },
  { min: 0, grade: 'F' },
];

/**
 * @param {number} score - Score in [0, 100].
 * @return {string} Letter grade.
 */
export function gradeForScore(score: number): string {
  const clamped = Math.max(0, Math.min(100, Math.round(score)));
  for (const band of GRADE_BANDS) {
    if (clamped >= band.min) return band.grade;
  }

  return 'F';
}

/**
 * @param {object} args
 * @param {number | undefined} args.totalConversations
 * @param {number | undefined} args.gapCount
 * @return {number} Agent quality in [0, 100].
 */
export function computeAgentQuality(args: {
  totalConversations?: number;
  gapCount?: number;
}): number {
  const total = args.totalConversations ?? 0;
  if (total <= 0) return 0;
  const gaps = Math.max(0, Math.min(total, args.gapCount ?? 0));

  return Math.max(0, Math.min(100, Math.round((1 - gaps / total) * 100)));
}

/**
 * @param {object} args
 * @param {number} args.visibility
 * @param {number} args.catalog
 * @param {number} args.agent
 * @return {{ total: number; grade: string }}
 */
export function computeReadinessScore(args: {
  visibility: number;
  catalog: number;
  agent: number;
}): { total: number; grade: string } {
  const total = Math.round(
    SCORE_WEIGHTS.visibility * args.visibility +
      SCORE_WEIGHTS.catalog * args.catalog +
      SCORE_WEIGHTS.agent * args.agent
  );

  return { total, grade: gradeForScore(total) };
}

/**
 * @param {Date} now
 * @return {"morning" | "afternoon" | "evening"}
 */
export function greetingBucket(
  now: Date = new Date()
): 'morning' | 'afternoon' | 'evening' {
  const hour = now.getHours();
  if (hour < 12) return 'morning';
  if (hour < 18) return 'afternoon';

  return 'evening';
}

/**
 * @param {Date} now
 * @param {string} name
 * @return {string}
 */
export function buildGreeting(now: Date, name: string): string {
  const word = `Good ${greetingBucket(now)}`;

  return name ? `${word}, ${name}` : word;
}

/**
 * @param {string | null | undefined} domain
 * @return {string}
 */
export function displayNameFromDomain(
  domain: string | null | undefined
): string {
  if (!domain) return '';
  let trimmed = String(domain).trim().toLowerCase();
  if (trimmed.startsWith('http://')) trimmed = trimmed.slice('http://'.length);
  if (trimmed.startsWith('https://'))
    trimmed = trimmed.slice('https://'.length);
  trimmed = trimmed.replace(/^www\./, '').split('/')[0] ?? '';
  const firstLabel = trimmed.split('.')[0] ?? '';
  if (!firstLabel) return '';

  return firstLabel.charAt(0).toUpperCase() + firstLabel.slice(1);
}