package uploads

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"math"
	"regexp"
	"sort"
	"strings"

	"github.com/google/uuid"
	"pipu/api/internal/library"
	"pipu/api/internal/library/meta"
	"pipu/api/internal/musicbrainz"
)

type ReleaseMatch struct {
	FileID     uuid.UUID `json:"file_id"`
	TrackIndex int       `json:"track_index"`
	Confidence string    `json:"confidence"`
	Method     string    `json:"method,omitempty"`
}
type ReleaseCandidate struct {
	Release    musicbrainz.Release `json:"release"`
	Matches    []ReleaseMatch      `json:"matches"`
	Missing    []musicbrainz.Track `json:"missing"`
	Existing   []musicbrainz.Track `json:"existing"`
	Unmatched  []uuid.UUID         `json:"unmatched"`
	Matched    int                 `json:"matched"`
	Total      int                 `json:"total"`
	Complete   bool                `json:"complete"`
	Confidence string              `json:"confidence"`
}
type ReleaseReport struct {
	GroupID         string             `json:"group_id,omitempty"`
	Groups          []ReleaseGroup     `json:"groups,omitempty"`
	State           string             `json:"state"`
	InputHash       string             `json:"input_hash"`
	Candidates      []ReleaseCandidate `json:"candidates"`
	SelectedRelease *string            `json:"selected_release"`
	AudioAvailable  bool               `json:"audio_available"`
	AudioResults    []AudioRecognition `json:"audio_results,omitempty"`
}

type AudioRecognition struct {
	FileID      uuid.UUID `json:"file_id"`
	State       string    `json:"state"`
	RecordingID string    `json:"recording_id,omitempty"`
	Score       float64   `json:"score,omitempty"`
}

func releaseFiles(files []File) []File {
	out := []File{}
	for _, f := range files {
		if f.Meta != nil && (f.Status == StatusPendingReview || f.Status == StatusImportFailed || f.Status == StatusDuplicate || f.Status == StatusImported || f.Status == StatusApproved || f.Status == StatusImporting) {
			out = append(out, f)
		}
	}
	return out
}
func releaseHash(files []File) string {
	type entry struct {
		ID       uuid.UUID
		Meta     *Meta
		Duration *int
		Tags     map[string]string
	}
	entries := []entry{}
	for _, f := range releaseFiles(files) {
		entries = append(entries, entry{f.ID, f.Meta, f.DurationMs, f.Tags})
	}
	sort.Slice(entries, func(i, j int) bool { return entries[i].ID.String() < entries[j].ID.String() })
	// Invalidate persisted reports when matching rules change, as well as tags.
	b, _ := json.Marshal(struct {
		Version int
		Files   []entry
	}{2, entries})
	h := sha256.Sum256(b)
	return hex.EncodeToString(h[:])
}
func tagID(tags map[string]string, keys ...string) string {
	for _, key := range keys {
		if id, err := uuid.Parse(strings.TrimSpace(tags[key])); err == nil {
			return id.String()
		}
	}
	return ""
}
func batchReleaseQuery(files []File) (musicbrainz.Query, bool) {
	q := musicbrainz.Query{}
	for _, f := range releaseFiles(files) {
		if id := tagID(f.Tags, "musicbrainz_albumid", "musicbrainz album id", "musicbrainz release id", "musicbrainz_releaseid"); id != "" {
			if q.ReleaseID != "" && q.ReleaseID != id {
				return musicbrainz.Query{}, false
			}
			q.ReleaseID = id
		}
	}
	if q.ReleaseID != "" {
		return q, true
	}
	for _, f := range releaseFiles(files) {
		m := f.Meta
		a := m.AlbumArtist
		if a == "" {
			a = m.Artist
		}
		if a == "" || m.Album == "" || m.Album == library.UnknownAlbum || len(a) > 500 || len(m.Album) > 500 {
			return q, false
		}
		if q.Artist != "" && (meta.Key(q.Artist) != meta.Key(a) || meta.Key(q.Album) != meta.Key(m.Album)) {
			return q, false
		}
		q.Artist, q.Album = a, m.Album
	}
	return q, q.Artist != ""
}

// Only credit annotations are removed for tentative matching. Version labels
// such as live, remix or instrumental remain significant.
var releaseTitleCredits = regexp.MustCompile(`(?i)\s*[\(\[]\s*(?:feat\.?|ft\.?|featuring|prod\.?|produced by)\s+[^()\[\]]+[\)\]]\s*$`)

func releaseTitleKey(title string) string {
	for {
		cleaned := releaseTitleCredits.ReplaceAllString(title, "")
		if cleaned == title {
			return meta.Key(title)
		}
		title = cleaned
	}
}

func sameReleaseArtists(a, b string) bool {
	left := meta.SplitArtists(strings.ToLower(a), nil)
	right := meta.SplitArtists(strings.ToLower(b), nil)
	if len(left) == 0 || len(left) != len(right) {
		return false
	}
	credits := make(map[string]bool, len(left))
	for _, artist := range left {
		credits[meta.Key(artist.Name)] = true
	}
	for _, artist := range right {
		if !credits[meta.Key(artist.Name)] {
			return false
		}
	}
	return true
}

func trackScore(f File, t musicbrainz.Track, albumArtist string) int {
	if f.Meta == nil {
		return 0
	}
	m := f.Meta
	delta := math.MaxFloat64
	if f.DurationMs != nil && *f.DurationMs > 0 && t.DurationMs > 0 {
		delta = math.Abs(float64(*f.DurationMs - t.DurationMs))
	}
	if id := tagID(f.Tags, "musicbrainz_trackid", "musicbrainz track id", "musicbrainz recording id", "musicbrainz_recordingid"); id != "" && id == t.RecordingID {
		if delta <= 5000 {
			return 100
		}
		return 70
	}
	title := meta.Key(m.Title) == meta.Key(t.Title) && meta.Key(t.Title) != ""
	artistMatch := meta.Key(m.Artist) == meta.Key(t.Artist) || m.AlbumArtist != "" && meta.Key(m.AlbumArtist) == meta.Key(albumArtist)
	if title && delta <= 3000 {
		if !artistMatch {
			return 70
		}
		return 95
	}
	if title && (t.DurationMs == 0 || f.DurationMs == nil) {
		return 70
	}
	if delta <= 2000 && m.Track != nil && *m.Track == t.Position && (m.Disc == nil && t.Disc == 1 || m.Disc != nil && *m.Disc == t.Disc) &&
		releaseTitleKey(m.Title) != "" && releaseTitleKey(m.Title) == releaseTitleKey(t.Title) && sameReleaseArtists(m.Artist, t.Artist) {
		return 75
	}
	return 0
}
func matchRelease(files []File, r musicbrainz.Release) ReleaseCandidate {
	return matchReleaseWithAudio(files, r, nil)
}
func matchReleaseWithAudio(files []File, r musicbrainz.Release, audio map[uuid.UUID]AudioRecognition) ReleaseCandidate {
	c := ReleaseCandidate{Release: r, Matches: []ReleaseMatch{}, Missing: []musicbrainz.Track{}, Existing: []musicbrainz.Track{}, Unmatched: []uuid.UUID{}, Total: len(r.Tracks), Confidence: "low"}
	covered := map[int]bool{}
	strong := true
	for _, f := range releaseFiles(files) {
		index, best, tied := -1, 0, false
		for i, t := range r.Tracks {
			score := trackScore(f, t, r.Artist)
			if a, ok := audio[f.ID]; ok && a.State == "matched" {
				score = 0
				if a.RecordingID == t.RecordingID {
					score = 70
					if f.DurationMs != nil && t.DurationMs > 0 && math.Abs(float64(*f.DurationMs-t.DurationMs)) <= 5000 {
						score = 100
					}
				}
			}
			if score > best {
				index, best, tied = i, score, false
			} else if score > 0 && score == best {
				tied = true
			}
		}
		if index < 0 || tied {
			c.Unmatched = append(c.Unmatched, f.ID)
			strong = false
			continue
		}
		confidence := "high"
		if best < 90 {
			confidence = "medium"
			strong = false
		}
		method := "metadata"
		if a, ok := audio[f.ID]; ok && a.State == "matched" {
			method = "acoustid"
		}
		c.Matches = append(c.Matches, ReleaseMatch{FileID: f.ID, TrackIndex: index, Confidence: confidence, Method: method})
		covered[index] = true
	}
	for i, t := range r.Tracks {
		if !covered[i] {
			c.Missing = append(c.Missing, t)
		}
	}
	c.Matched = len(covered)
	c.Complete = strong && c.Total > 0 && c.Matched == c.Total && len(c.Unmatched) == 0
	if strong && c.Matched > 0 {
		c.Confidence = "high"
	} else if c.Matched > 0 {
		c.Confidence = "medium"
	}
	return c
}