package model

import (
	"context"
	"iter"
	"maps"
	"os"
	"path/filepath"
	"slices"
	"strconv"
	"time"

	"github.com/deluan/rest"
	"github.com/navidrome/navidrome/conf"
	"github.com/navidrome/navidrome/consts"
	"github.com/navidrome/navidrome/log"
	"github.com/navidrome/navidrome/model/criteria"
)

type Playlist struct {
	Annotations `structs:"-"`
	ItemImage   `structs:"-"`

	ID               string         `structs:"id" json:"id"`
	Name             string         `structs:"name" json:"name"`
	Comment          string         `structs:"comment" json:"comment"`
	Duration         float32        `structs:"duration" json:"duration"`
	Size             int64          `structs:"size" json:"size"`
	SongCount        int            `structs:"song_count" json:"songCount"`
	OwnerName        string         `structs:"-" json:"ownerName"`
	OwnerID          string         `structs:"owner_id" json:"ownerId"`
	Public           bool           `structs:"public" json:"public"`
	Tracks           PlaylistTracks `structs:"-" json:"tracks,omitempty"`
	Path             string         `structs:"path" json:"path"`
	Sync             bool           `structs:"sync" json:"sync"`
	UploadedImage    string         `structs:"uploaded_image" json:"uploadedImage"`
	ExternalImageURL string         `structs:"external_image_url" json:"externalImageUrl,omitempty"`
	CreatedAt        time.Time      `structs:"created_at" json:"createdAt"`
	UpdatedAt        time.Time      `structs:"updated_at" json:"updatedAt"`
	ImportedHash     string         `structs:"imported_hash" json:"-"`

	// SmartPlaylist attributes
	Rules       *criteria.Criteria `structs:"rules" json:"rules"`
	EvaluatedAt *time.Time         `structs:"evaluated_at" json:"evaluatedAt"`
}

func (pls Playlist) IsSmartPlaylist() bool {
	return pls.Rules != nil && pls.Rules.Expression != nil
}

// TracksEditable reports whether the track list is user-owned rather than server-managed.
func (pls Playlist) TracksEditable() bool {
	return !pls.IsSmartPlaylist() && !pls.Sync
}

// RefreshDelay returns the playlist's own refresh window when set, falling
// back to the global SmartPlaylistRefreshDelay.
func (pls Playlist) RefreshDelay() time.Duration {
	if pls.IsSmartPlaylist() && pls.Rules.RefreshDelay > 0 {
		return pls.Rules.RefreshDelay
	}
	return conf.Server.SmartPlaylistRefreshDelay
}

func (pls Playlist) MediaFiles() MediaFiles {
	if len(pls.Tracks) == 0 {
		return nil
	}
	return pls.Tracks.MediaFiles()
}

func (pls *Playlist) refreshStats() {
	pls.SongCount = len(pls.Tracks)
	pls.Duration = 0
	pls.Size = 0
	for _, t := range pls.Tracks {
		pls.Duration += t.MediaFile.Duration
		pls.Size += t.MediaFile.Size
	}
}

func (pls *Playlist) SetTracks(tracks PlaylistTracks) {
	pls.Tracks = tracks
	pls.refreshStats()
}

func (pls *Playlist) RemoveTracks(idxToRemove []int) {
	var newTracks PlaylistTracks
	for i, t := range pls.Tracks {
		if slices.Contains(idxToRemove, i) {
			continue
		}
		newTracks = append(newTracks, t)
	}
	pls.Tracks = newTracks
	pls.refreshStats()
}

// ToM3U8 exports the playlist to the Extended M3U8 format
func (pls *Playlist) ToM3U8() string {
	return pls.MediaFiles().ToM3U8(pls.Name, true)
}

func (pls *Playlist) AddMediaFilesByID(mediaFileIds []string) {
	pos := len(pls.Tracks)
	for _, mfId := range mediaFileIds {
		pos++
		t := PlaylistTrack{
			ID:          strconv.Itoa(pos),
			MediaFileID: mfId,
			MediaFile:   MediaFile{ID: mfId},
			PlaylistID:  pls.ID,
		}
		pls.Tracks = append(pls.Tracks, t)
	}
	pls.refreshStats()
}

func (pls *Playlist) AddMediaFiles(mfs MediaFiles) {
	pos := len(pls.Tracks)
	for _, mf := range mfs {
		pos++
		t := PlaylistTrack{
			ID:          strconv.Itoa(pos),
			MediaFileID: mf.ID,
			MediaFile:   mf,
			PlaylistID:  pls.ID,
		}
		pls.Tracks = append(pls.Tracks, t)
	}
	pls.refreshStats()
}

func (pls Playlist) CoverArtID() ArtworkID {
	return artworkIDFromPlaylist(pls)
}

// UploadedImagePath returns the absolute filesystem path for a manually uploaded
// playlist cover image. Returns empty string if no image has been uploaded.
// This does NOT cover sidecar images or external URLs — those are resolved
// by the artwork reader's fallback chain.
func (pls Playlist) UploadedImagePath() string {
	return UploadedImagePath(consts.EntityPlaylist, pls.UploadedImage)
}

// NormalizedRules returns the rules with child playlist paths resolved to absolute, OS-native paths.
func (pls Playlist) NormalizedRules() *criteria.Criteria {
	if pls.Rules == nil || pls.Rules.Expression == nil {
		return pls.Rules
	}

	rules := *pls.Rules
	rules.Expression = normalizePlaylistPaths(pls.Rules.Expression, pls.Path)
	return &rules
}

func normalizePlaylistPaths(inputRule criteria.Expression, referencingPlaylistPath string) criteria.Expression {
	switch rule := inputRule.(type) {
	case criteria.Any:
		anyCriteria := make(criteria.Any, len(rule))
		for i, rules := range rule {
			anyCriteria[i] = normalizePlaylistPaths(rules, referencingPlaylistPath)
		}
		return anyCriteria
	case criteria.All:
		allCriteria := make(criteria.All, len(rule))
		for i, rules := range rule {
			allCriteria[i] = normalizePlaylistPaths(rules, referencingPlaylistPath)
		}
		return allCriteria
	case criteria.InPlaylist:
		return criteria.InPlaylist(normalizeChildPathRule(rule, referencingPlaylistPath))
	case criteria.NotInPlaylist:
		return criteria.NotInPlaylist(normalizeChildPathRule(rule, referencingPlaylistPath))
	}

	return inputRule
}

func normalizeChildPathRule(rule map[string]any, referencingPlaylistPath string) map[string]any {
	path, ok := rule["path"].(string)
	if !ok || path == "" {
		return rule
	}

	// References use forward slashes to stay portable, while Playlist.Path is OS-native.
	path = filepath.FromSlash(path)
	switch {
	case isAbsPlaylistRef(path):
		path = filepath.Clean(path)
	case referencingPlaylistPath != "":
		path = filepath.Join(filepath.Dir(referencingPlaylistPath), path)
	default:
		log.Warn("Cannot resolve relative playlist reference: playlist has no file path", "reference", path)
	}
	normalized := maps.Clone(rule)
	normalized["path"] = path
	return normalized
}

// filepath.IsAbs rejects a bare leading separator on Windows, but that is how Unix spells absolute.
func isAbsPlaylistRef(path string) bool {
	return filepath.IsAbs(path) || os.IsPathSeparator(path[0])
}

type Playlists []Playlist

type PlaylistCursor iter.Seq2[Playlist, error]

type PlaylistRepository interface {
	rest.Repository[Playlist]
	rest.Persistable[Playlist]
	AnnotatedRepository
	CountAll(ctx context.Context, options ...QueryOptions) (int64, error)
	Exists(ctx context.Context, id string) (bool, error)
	Put(ctx context.Context, pls *Playlist, cols ...string) error
	Get(ctx context.Context, id string) (*Playlist, error)
	GetWithTracks(ctx context.Context, id string, refreshSmartPlaylist, includeMissing bool) (*Playlist, error)
	GetAll(ctx context.Context, options ...QueryOptions) (Playlists, error)
	GetCursor(ctx context.Context, options ...QueryOptions) (PlaylistCursor, error)
	FindByPath(ctx context.Context, path string) (*Playlist, error)
	Tracks(ctx context.Context, playlistId string, refreshSmartPlaylist bool) PlaylistTrackRepository
	GetPlaylists(ctx context.Context, mediaFileId string) (Playlists, error)
}

type PlaylistTrack struct {
	ID          string `json:"id"`
	MediaFileID string `json:"mediaFileId"`
	PlaylistID  string `json:"playlistId"`
	MediaFile
}

type PlaylistTracks []PlaylistTrack

func (plt PlaylistTracks) MediaFiles() MediaFiles {
	mfs := make(MediaFiles, len(plt))
	for i, t := range plt {
		mfs[i] = t.MediaFile
	}
	return mfs
}

type PlaylistTrackCursor iter.Seq2[PlaylistTrack, error]

type PlaylistTrackRepository interface {
	rest.Repository[PlaylistTrack]
	CountAll(ctx context.Context, options ...QueryOptions) (int64, error)
	GetAll(ctx context.Context, options ...QueryOptions) (PlaylistTracks, error)
	GetCursor(ctx context.Context, options ...QueryOptions) (PlaylistTrackCursor, error)
	GetAlbumIDs(ctx context.Context, options ...QueryOptions) ([]string, error)
	GetMediaFileIDs(ctx context.Context, options ...QueryOptions) ([]string, error)
	Add(ctx context.Context, mediaFileIds []string) (int, error)
	Insert(ctx context.Context, mediaFileIds []string, pos int) (int, error)
	AddAlbums(ctx context.Context, albumIds []string) (int, error)
	AddArtists(ctx context.Context, artistIds []string) (int, error)
	AddDiscs(ctx context.Context, discs []DiscID) (int, error)
	Delete(ctx context.Context, id ...string) error
	DeleteAll(ctx context.Context) error
	Reorder(ctx context.Context, pos int, newPos int) error
}