package reader

import (
	"strings"
	"unicode"
)

type Word struct {
	Text   string `json:"text"`
	Prefix string `json:"prefix"`
	Focus  string `json:"focus"`
	Suffix string `json:"suffix"`
}

// Tokenize splits text into words while ignoring repeated whitespace.
func Tokenize(text string) []Word {
	fields := strings.Fields(text)
	words := make([]Word, 0, len(fields))

	for _, field := range fields {
		words = append(words, SplitWord(field))
	}

	return words
}

// SplitWord separates a word into its prefix, focus character and suffix.
func SplitWord(word string) Word {
	if word == "" {
		return Word{}
	}

	runes := []rune(word)
	position := ORPIndex(runes)

	// Keep the focus index inside the word.
	if position >= len(runes) {
		position = len(runes) - 1
	}

	return Word{
		Text:   word,
		Prefix: string(runes[:position]),
		Focus:  string(runes[position : position+1]),
		Suffix: string(runes[position+1:]),
	}
}

// lastMeaningfulRune returns the last rune after ignoring
// closing quotes and brackets.
func lastMeaningfulRune(word string) rune {
	word = strings.TrimRightFunc(word, func(r rune) bool {
		switch r {
		case '"', '\'', '”', '’', ')', ']', '}', '»':
			return true
		default:
			return false
		}
	})

	runes := []rune(word)
	if len(runes) == 0 {
		return 0
	}

	return runes[len(runes)-1]
}

// IsSentenceEnding checks whether a word ends a sentence.
func IsSentenceEnding(word string) bool {
	switch lastMeaningfulRune(word) {
	case '.', '!', '?', '…':
		return true
	default:
		return false
	}
}

// IsPausePunctuation checks for punctuation that should
// introduce a short pause during playback.
func IsPausePunctuation(word string) bool {
	switch lastMeaningfulRune(word) {
	case ',', ';', ':':
		return true
	default:
		return false
	}
}

// RuneLength returns the number of Unicode characters in a word.
func RuneLength(word string) int {
	return len([]rune(word))
}

// IsPunctuation reports whether the final meaningful character is punctuation.
func IsPunctuation(word string) bool {
	return unicode.IsPunct(lastMeaningfulRune(word))
}