package backchannel

import (
	"regexp"
	"strings"
	"unicode"

	"gitea.maximumdirect.net/eric/seriatim/internal/model"
)

const Category = "backchannel"

var patterns = []*regexp.Regexp{
	regexp.MustCompile(`(?i)^(yeah|yep|yes|right|okay|ok|sure|mm+h?m+|mm+\s+hmm|uh[- ]huh|mhm|mm-hmm)\.?$`),
	regexp.MustCompile(`(?i)^(yeah|yep|right|okay|ok)([,.\s]+(yeah|yep|right|okay|ok))*\.?$`),
	regexp.MustCompile(`(?i)^(i see|got it|makes sense|that makes sense|fair enough|sounds good|there you go)\.?$`),
}

// Apply tags matching short acknowledgement segments.
func Apply(in model.MergedTranscript, maxDuration float64) (model.MergedTranscript, int) {
	tagged := 0
	for index := range in.Segments {
		if !matches(in.Segments[index], maxDuration) {
			continue
		}
		if hasCategory(in.Segments[index], Category) {
			continue
		}
		in.Segments[index].Categories = append(in.Segments[index].Categories, Category)
		tagged++
	}
	return in, tagged
}

func matches(segment model.Segment, maxDuration float64) bool {
	text := normalizeForMatching(segment.Text)
	if text == "" {
		return false
	}
	if len(strings.Fields(text)) > 3 {
		return false
	}
	if segment.End-segment.Start > maxDuration {
		return false
	}
	for _, pattern := range patterns {
		if pattern.MatchString(text) {
			return true
		}
	}
	return false
}

func normalizeForMatching(text string) string {
	text = strings.Map(func(r rune) rune {
		if unicode.IsPunct(r) {
			return ' '
		}
		return r
	}, text)
	return strings.Join(strings.Fields(text), " ")
}

func hasCategory(segment model.Segment, category string) bool {
	for _, existing := range segment.Categories {
		if existing == category {
			return true
		}
	}
	return false
}