package scan

import "strings"

// TitleMatcher returns true if a title should be kept.
type TitleMatcher func(title string) bool

// NewTitleMatcher builds a case-insensitive positive/negative matcher.
// At least one positive must match (or positives empty) AND zero negatives.
func NewTitleMatcher(f TitleFilter) TitleMatcher {
	pos := lower(f.Positive)
	neg := lower(f.Negative)
	return func(title string) bool {
		lt := strings.ToLower(title)
		hasPos := len(pos) == 0
		for _, p := range pos {
			if strings.Contains(lt, p) {
				hasPos = true
				break
			}
		}
		if !hasPos {
			return false
		}
		for _, n := range neg {
			if strings.Contains(lt, n) {
				return false
			}
		}
		return true
	}
}

func lower(ss []string) []string {
	out := make([]string, 0, len(ss))
	for _, s := range ss {
		out = append(out, strings.ToLower(s))
	}
	return out
}