package reader

import "time"

const (
	MinWPM = 100
	MaxWPM = 1000
)

// WordDuration calculates how long a word should be displayed
// at the specified reading speed.
func WordDuration(word string, wpm int) time.Duration {
	// Enforce supported reading speed limits.
	if wpm < MinWPM {
		wpm = MinWPM
	}

	if wpm > MaxWPM {
		wpm = MaxWPM
	}

	// Base duration for one word.
	duration := time.Minute / time.Duration(wpm)

	// Add pauses for punctuation.
	switch {
	case IsSentenceEnding(word):
		duration += 300 * time.Millisecond
	case IsPausePunctuation(word):
		duration += 150 * time.Millisecond
	}

	// Allow slightly more time for longer words.
	if RuneLength(word) >= 10 {
		duration += 50 * time.Millisecond
	}

	return duration
}