package uploads

import (
	"context"
	"errors"
	"sort"

	"github.com/google/uuid"
	"pipu/api/internal/acoustid"
)

const maxAudioFiles = 50

func chooseAudioMatch(id uuid.UUID, matches []acoustid.Match) AudioRecognition {
	// Multiple AcoustIDs can point to the same recording. Compare distinct recordings only.
	best := map[string]float64{}
	for _, m := range matches {
		if parsed, err := uuid.Parse(m.RecordingID); err == nil && parsed != uuid.Nil && m.Score > best[parsed.String()] && m.Score <= 1 {
			best[parsed.String()] = m.Score
		}
	}
	unique := []acoustid.Match{}
	for id, score := range best {
		unique = append(unique, acoustid.Match{RecordingID: id, Score: score})
	}
	sort.Slice(unique, func(i, j int) bool { return unique[i].Score > unique[j].Score })
	r := AudioRecognition{FileID: id, State: "not_found"}
	if len(unique) == 0 {
		return r
	}
	r.Score = unique[0].Score
	if unique[0].Score < .9 || len(unique) > 1 && unique[0].Score-unique[1].Score < .05 {
		r.State = "ambiguous"
		return r
	}
	r.State, r.RecordingID = "matched", unique[0].RecordingID
	return r
}

// identifyAudio runs only after an explicit reviewer request. It never modifies file tags.
func (s *Service) identifyAudio(ctx context.Context, files []File) ([]AudioRecognition, map[uuid.UUID]AudioRecognition, []string, error) {
	results := []AudioRecognition{}
	byFile := map[uuid.UUID]AudioRecognition{}
	ids := []string{}
	if s.identifier == nil || s.encodedFingerprint == nil {
		return results, byFile, ids, errors.New("acoustid: not configured")
	}
	for _, f := range releaseFiles(files) {
		if f.Status != StatusPendingReview && f.Status != StatusImportFailed {
			continue
		}
		if len(results) >= maxAudioFiles {
			return results, byFile, ids, errors.New("acoustid: batch too large")
		}
		r := AudioRecognition{FileID: f.ID, State: "unavailable"}
		if f.DurationMs != nil && *f.DurationMs > 0 && f.StagingPath != "" {
			fingerprint, err := s.encodedFingerprint(ctx, s.stagingAbs(f.StagingPath))
			if err == nil {
				matches, err := s.identifier.Lookup(ctx, fingerprint, (*f.DurationMs+500)/1000)
				if err != nil {
					return results, byFile, ids, err
				}
				r = chooseAudioMatch(f.ID, matches)
			}
		}
		if err := ctx.Err(); err != nil {
			return results, byFile, ids, err
		}
		results = append(results, r)
		byFile[f.ID] = r
		if r.State == "matched" {
			ids = append(ids, r.RecordingID)
		}
	}
	return results, byFile, ids, nil
}