// Spritz ORP algorithm - position where the eye naturally fixates.
// Based on Optimal Viewing Position research (20-35% from left).
export function getORPIndex(wordLength: number): number {
  if (wordLength <= 0) return 0;
  if (wordLength === 1) return 0; // 1 char: 1st letter
  if (wordLength <= 5) return 1; // 2-5 chars: 2nd letter
  if (wordLength <= 9) return 2; // 6-9 chars: 3rd letter
  if (wordLength <= 13) return 3; // 10-13 chars: 4th letter
  return 4; // 14+ chars: 5th letter
}

function stripTrailingClosers(s: string): string {
  // Handle punctuation followed by quotes/brackets like `word."` or `word.)`.
  return s.replace(/[)"'\]]+$/g, "");
}

export function getTimingMultiplier(text: string, adaptiveTiming: boolean): number {
  if (!adaptiveTiming) return 1;

  const tokens = text.trim().split(/\s+/).filter(Boolean);
  if (tokens.length === 0) return 1;

  // Length-based slowdown: use the longest token in the display chunk.
  let maxLen = 0;
  for (const t of tokens) maxLen = Math.max(maxLen, t.length);
  let multiplier = 1 + Math.sqrt(maxLen) * 0.04;

  // Punctuation-based pauses: based on the last token.
  const last = stripTrailingClosers(tokens[tokens.length - 1]);
  if (/[.!?]$/.test(last)) {
    multiplier = Math.max(multiplier, 2.5);
  } else if (/[,;:]$/.test(last)) {
    multiplier = Math.max(multiplier, 1.8);
  }

  return multiplier;
}

export function getTimingMultiplierForWords(
  words: string[],
  startIndex: number,
  endIndex: number,
  adaptiveTiming: boolean,
): number {
  if (!adaptiveTiming) return 1;
  if (endIndex <= startIndex) return 1;

  let maxLen = 0;
  for (let i = startIndex; i < endIndex; i++) {
    const w = words[i];
    if (w && w.length > maxLen) maxLen = w.length;
  }
  let multiplier = 1 + Math.sqrt(maxLen) * 0.04;

  const lastToken = words[endIndex - 1] || "";
  const last = stripTrailingClosers(lastToken);
  if (/[.!?]$/.test(last)) {
    multiplier = Math.max(multiplier, 2.5);
  } else if (/[,;:]$/.test(last)) {
    multiplier = Math.max(multiplier, 1.8);
  }
  return multiplier;
}

export function getWordDelay(
  text: string,
  baseDelayMs: number,
  adaptiveTiming: boolean,
): number {
  return baseDelayMs * getTimingMultiplier(text, adaptiveTiming);
}

export function getWordDelayForWords(
  words: string[],
  startIndex: number,
  endIndex: number,
  baseDelayMs: number,
  adaptiveTiming: boolean,
): number {
  return (
    baseDelayMs *
    getTimingMultiplierForWords(words, startIndex, endIndex, adaptiveTiming)
  );
}

export function formatReadingTime(minutes: number): string {
  minutes = Math.round(minutes);
  if (minutes < 1) return "< 1 min";
  if (minutes < 60) return `${Math.round(minutes)} min`;
  const hours = Math.floor(minutes / 60);
  const mins = Math.round(minutes % 60);
  if (mins === 0) return `${hours}h`;
  return `${hours}h ${mins}m`;
}