// Package detector provides music link detection in text.
package detector

import (
	"regexp"

	"musiclink/internal/services"
)

// patterns match music service URLs.
// We keep patterns per service for easier maintenance.
var patterns = []*regexp.Regexp{
	regexp.MustCompile(`https?://(?:open\.)?spotify\.com/(?:track|album|artist|playlist)/[a-zA-Z0-9]+`),
	regexp.MustCompile(`https?://spoti\.fi/[a-zA-Z0-9]+`),
	regexp.MustCompile(`https?://(?:www\.)?(?:youtube\.com/watch\?v=|youtu\.be/|music\.youtube\.com/watch\?v=)[a-zA-Z0-9_-]{11}`),
	regexp.MustCompile(`https?://(?:(?:music|geo\.music)\.)?apple\.com/[a-z]{2}/(?:album|artist|playlist|song)/[^\s]+`),
	regexp.MustCompile(`https?://(?:www\.)?deezer\.com/(?:[a-z]{2}/)?(?:track|album|artist|playlist)/\d+`),
	regexp.MustCompile(`https?://(?:www\.)?soundcloud\.com/[a-zA-Z0-9_-]+/[a-zA-Z0-9_-]+`),
	regexp.MustCompile(`https?://(?:www\.)?tidal\.com/(?:browse/)?(?:track|album|artist|playlist)/\d+`),
	regexp.MustCompile(`https?://(?:www\.)?qobuz\.com/[a-z]{2}-[a-z]{2}/(?:album|track|artist|playlist)/[^\s]+`),
	regexp.MustCompile(`https?://[a-zA-Z0-9_-]+\.bandcamp\.com/(?:track|album)/[a-zA-Z0-9_-]+`),
}

// Detector finds music links in text.
type Detector struct{}

// New creates a new Detector.
func New() *Detector {
	return &Detector{}
}

// Detect finds all music links in the given text.
func (d *Detector) Detect(text string) []services.DetectedLink {
	matches := findMatches(text)
	if len(matches) == 0 {
		return nil
	}

	links := make([]services.DetectedLink, len(matches))
	for i, match := range matches {
		links[i] = services.DetectedLink{
			URL:      match,
			RawMatch: match,
		}
	}

	return links
}

func findMatches(text string) []string {
	var matches []string
	seen := make(map[string]struct{})
	for _, re := range patterns {
		for _, match := range re.FindAllString(text, -1) {
			if _, ok := seen[match]; ok {
				continue
			}
			seen[match] = struct{}{}
			matches = append(matches, match)
		}
	}
	return matches
}