package model

import (
	"context"
	"errors"
	"strconv"
	"time"

	"gorm.io/gorm"

	"spark-server/internal/module/music/entity"
)

type Repo struct {
	db *gorm.DB
}

func NewRepo(db *gorm.DB) *Repo {
	if db == nil {
		return nil
	}
	return &Repo{db: db}
}

func (r *Repo) Ready() bool {
	return r != nil && r.db != nil
}

type trackRow struct {
	ID            int64     `gorm:"column:id;primaryKey"`
	Title         string    `gorm:"column:title"`
	CoverKey      string    `gorm:"column:cover_key"`
	AudioKey      string    `gorm:"column:audio_key"`
	BackgroundKey string    `gorm:"column:background_key"`
	CoverURL      string    `gorm:"column:cover_url"`
	AudioURL      string    `gorm:"column:audio_url"`
	BackgroundURL string    `gorm:"column:background_url"`
	RequireMember bool      `gorm:"column:require_member"`
	SortOrder     int       `gorm:"column:sort_order"`
	Enabled       bool      `gorm:"column:enabled"`
	CreatedAt     time.Time `gorm:"column:created_at"`
	UpdatedAt     time.Time `gorm:"column:updated_at"`
}

func (trackRow) TableName() string { return "t_music_tracks" }

type settingRow struct {
	SettingKey   string    `gorm:"column:setting_key;primaryKey"`
	SettingValue string    `gorm:"column:setting_value"`
	UpdatedAt    time.Time `gorm:"column:updated_at"`
}

func (settingRow) TableName() string { return "t_music_settings" }

type categoryRow struct {
	ID        int64     `gorm:"column:id;primaryKey"`
	ParentID  *int64    `gorm:"column:parent_id"`
	Name      string    `gorm:"column:name"`
	SortOrder int       `gorm:"column:sort_order"`
	Enabled   bool      `gorm:"column:enabled"`
	CreatedAt time.Time `gorm:"column:created_at"`
	UpdatedAt time.Time `gorm:"column:updated_at"`
}

func (categoryRow) TableName() string { return "t_music_categories" }

type categoryTrackRow struct {
	CategoryID int64     `gorm:"column:category_id;primaryKey"`
	TrackID    int64     `gorm:"column:track_id;primaryKey"`
	CreatedAt  time.Time `gorm:"column:created_at"`
}

func (categoryTrackRow) TableName() string { return "t_music_category_tracks" }

func (r *Repo) ListAll(ctx context.Context) ([]entity.Track, error) {
	if !r.Ready() {
		return nil, errors.New("music repo not ready")
	}
	var rows []trackRow
	err := r.db.WithContext(ctx).Order("sort_order ASC, id ASC").Find(&rows).Error
	if err != nil {
		return nil, err
	}
	out := make([]entity.Track, 0, len(rows))
	for i := range rows {
		out = append(out, toEntity(&rows[i]))
	}
	return r.attachCategoryIDs(ctx, out)
}

func (r *Repo) ListEnabled(ctx context.Context) ([]entity.Track, error) {
	if !r.Ready() {
		return nil, errors.New("music repo not ready")
	}
	var rows []trackRow
	err := r.db.WithContext(ctx).Where("enabled = ?", true).Order("sort_order ASC, id ASC").Find(&rows).Error
	if err != nil {
		return nil, err
	}
	out := make([]entity.Track, 0, len(rows))
	for i := range rows {
		out = append(out, toEntity(&rows[i]))
	}
	return r.attachCategoryIDs(ctx, out)
}

func (r *Repo) ListEnabledByCategory(ctx context.Context, categoryID int64) ([]entity.Track, error) {
	if !r.Ready() {
		return nil, errors.New("music repo not ready")
	}
	ids, err := r.categoryScopeIDs(ctx, categoryID)
	if err != nil {
		return nil, err
	}
	if len(ids) == 0 {
		return []entity.Track{}, nil
	}
	var trackIDs []int64
	err = r.db.WithContext(ctx).Model(&categoryTrackRow{}).
		Where("category_id IN ?", ids).Distinct("track_id").Pluck("track_id", &trackIDs).Error
	if err != nil {
		return nil, err
	}
	if len(trackIDs) == 0 {
		return []entity.Track{}, nil
	}
	var rows []trackRow
	err = r.db.WithContext(ctx).Where("enabled = ? AND id IN ?", true, trackIDs).
		Order("sort_order ASC, id ASC").Find(&rows).Error
	if err != nil {
		return nil, err
	}
	out := make([]entity.Track, 0, len(rows))
	for i := range rows {
		out = append(out, toEntity(&rows[i]))
	}
	return r.attachCategoryIDs(ctx, out)
}

func (r *Repo) categoryScopeIDs(ctx context.Context, categoryID int64) ([]int64, error) {
	var all []categoryRow
	if err := r.db.WithContext(ctx).Find(&all).Error; err != nil {
		return nil, err
	}
	byParent := map[int64][]int64{}
	for i := range all {
		c := &all[i]
		if c.ParentID != nil {
			byParent[*c.ParentID] = append(byParent[*c.ParentID], c.ID)
		}
	}
	out := []int64{categoryID}
	queue := []int64{categoryID}
	for len(queue) > 0 {
		cur := queue[0]
		queue = queue[1:]
		for _, child := range byParent[cur] {
			out = append(out, child)
			queue = append(queue, child)
		}
	}
	return out, nil
}

func (r *Repo) Get(ctx context.Context, id int64) (*entity.Track, error) {
	if !r.Ready() {
		return nil, errors.New("music repo not ready")
	}
	var row trackRow
	err := r.db.WithContext(ctx).First(&row, id).Error
	if err != nil {
		return nil, err
	}
	t := toEntity(&row)
	ids, err := r.TrackCategoryIDs(ctx, id)
	if err != nil {
		return nil, err
	}
	t.CategoryIDs = ids
	return &t, nil
}

func (r *Repo) Insert(ctx context.Context, t *entity.Track) error {
	if !r.Ready() {
		return errors.New("music repo not ready")
	}
	now := time.Now().UTC()
	row := trackRow{
		Title:         t.Title,
		CoverKey:      t.CoverKey,
		AudioKey:      t.AudioKey,
		BackgroundKey: t.BackgroundKey,
		CoverURL:      t.CoverURL,
		AudioURL:      t.AudioURL,
		BackgroundURL: t.BackgroundURL,
		RequireMember: t.RequireMember,
		SortOrder:     t.SortOrder,
		Enabled:       t.Enabled,
		CreatedAt:     now,
		UpdatedAt:     now,
	}
	if err := r.db.WithContext(ctx).Create(&row).Error; err != nil {
		return err
	}
	t.ID = row.ID
	t.CreatedAt = row.CreatedAt
	t.UpdatedAt = row.UpdatedAt
	if t.CategoryIDs == nil {
		t.CategoryIDs = []int64{}
	}
	return nil
}

func (r *Repo) Update(ctx context.Context, t *entity.Track) error {
	if !r.Ready() {
		return errors.New("music repo not ready")
	}
	now := time.Now().UTC()
	t.UpdatedAt = now
	return r.db.WithContext(ctx).Model(&trackRow{}).Where("id = ?", t.ID).Updates(map[string]any{
		"title":          t.Title,
		"cover_key":      t.CoverKey,
		"audio_key":      t.AudioKey,
		"background_key": t.BackgroundKey,
		"cover_url":      t.CoverURL,
		"audio_url":      t.AudioURL,
		"background_url": t.BackgroundURL,
		"require_member": t.RequireMember,
		"sort_order":     t.SortOrder,
		"enabled":        t.Enabled,
		"updated_at":     now,
	}).Error
}

func (r *Repo) Delete(ctx context.Context, id int64) error {
	if !r.Ready() {
		return errors.New("music repo not ready")
	}
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := tx.Where("track_id = ?", id).Delete(&categoryTrackRow{}).Error; err != nil {
			return err
		}
		return tx.Delete(&trackRow{}, id).Error
	})
}

func (r *Repo) GetSetting(ctx context.Context, key string) (string, error) {
	if !r.Ready() {
		return "", errors.New("music repo not ready")
	}
	var row settingRow
	err := r.db.WithContext(ctx).Where("setting_key = ?", key).First(&row).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return "", nil
	}
	if err != nil {
		return "", err
	}
	return row.SettingValue, nil
}

func (r *Repo) SetSetting(ctx context.Context, key, value string) error {
	if !r.Ready() {
		return errors.New("music repo not ready")
	}
	now := time.Now().UTC()
	row := settingRow{SettingKey: key, SettingValue: value, UpdatedAt: now}
	return r.db.WithContext(ctx).Save(&row).Error
}

func (r *Repo) MemberPreviewSeconds(ctx context.Context) (int, error) {
	raw, err := r.GetSetting(ctx, entity.SettingMemberPreviewSeconds)
	if err != nil {
		return entity.DefaultPreviewSeconds, err
	}
	if raw == "" {
		return entity.DefaultPreviewSeconds, nil
	}
	n, err := strconv.Atoi(raw)
	if err != nil || n < 0 {
		return entity.DefaultPreviewSeconds, nil
	}
	return n, nil
}

func (r *Repo) ListCategories(ctx context.Context) ([]entity.Category, error) {
	if !r.Ready() {
		return nil, errors.New("music repo not ready")
	}
	var rows []categoryRow
	err := r.db.WithContext(ctx).Order("sort_order ASC, id ASC").Find(&rows).Error
	if err != nil {
		return nil, err
	}
	out := make([]entity.Category, 0, len(rows))
	for i := range rows {
		out = append(out, toCategoryEntity(&rows[i]))
	}
	return out, nil
}

func (r *Repo) ListEnabledCategories(ctx context.Context) ([]entity.Category, error) {
	if !r.Ready() {
		return nil, errors.New("music repo not ready")
	}
	var rows []categoryRow
	err := r.db.WithContext(ctx).Where("enabled = ?", true).Order("sort_order ASC, id ASC").Find(&rows).Error
	if err != nil {
		return nil, err
	}
	out := make([]entity.Category, 0, len(rows))
	for i := range rows {
		out = append(out, toCategoryEntity(&rows[i]))
	}
	return out, nil
}

func (r *Repo) GetCategory(ctx context.Context, id int64) (*entity.Category, error) {
	if !r.Ready() {
		return nil, errors.New("music repo not ready")
	}
	var row categoryRow
	err := r.db.WithContext(ctx).First(&row, id).Error
	if err != nil {
		return nil, err
	}
	c := toCategoryEntity(&row)
	return &c, nil
}

func (r *Repo) InsertCategory(ctx context.Context, c *entity.Category) error {
	if !r.Ready() {
		return errors.New("music repo not ready")
	}
	now := time.Now().UTC()
	row := categoryRow{
		ParentID:  c.ParentID,
		Name:      c.Name,
		SortOrder: c.SortOrder,
		Enabled:   c.Enabled,
		CreatedAt: now,
		UpdatedAt: now,
	}
	if err := r.db.WithContext(ctx).Create(&row).Error; err != nil {
		return err
	}
	c.ID = row.ID
	c.CreatedAt = row.CreatedAt
	c.UpdatedAt = row.UpdatedAt
	return nil
}

func (r *Repo) UpdateCategory(ctx context.Context, c *entity.Category) error {
	if !r.Ready() {
		return errors.New("music repo not ready")
	}
	now := time.Now().UTC()
	c.UpdatedAt = now
	return r.db.WithContext(ctx).Model(&categoryRow{}).Where("id = ?", c.ID).Updates(map[string]any{
		"parent_id":  c.ParentID,
		"name":       c.Name,
		"sort_order": c.SortOrder,
		"enabled":    c.Enabled,
		"updated_at": now,
	}).Error
}

func (r *Repo) DeleteCategory(ctx context.Context, id int64) error {
	if !r.Ready() {
		return errors.New("music repo not ready")
	}
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var childIDs []int64
		if err := tx.Model(&categoryRow{}).Where("parent_id = ?", id).Pluck("id", &childIDs).Error; err != nil {
			return err
		}
		all := append([]int64{id}, childIDs...)
		if err := tx.Where("category_id IN ?", all).Delete(&categoryTrackRow{}).Error; err != nil {
			return err
		}
		if len(childIDs) > 0 {
			if err := tx.Where("id IN ?", childIDs).Delete(&categoryRow{}).Error; err != nil {
				return err
			}
		}
		return tx.Delete(&categoryRow{}, id).Error
	})
}

func (r *Repo) TrackCategoryIDs(ctx context.Context, trackID int64) ([]int64, error) {
	if !r.Ready() {
		return nil, errors.New("music repo not ready")
	}
	var ids []int64
	err := r.db.WithContext(ctx).Model(&categoryTrackRow{}).
		Where("track_id = ?", trackID).Order("category_id ASC").Pluck("category_id", &ids).Error
	if err != nil {
		return nil, err
	}
	if ids == nil {
		ids = []int64{}
	}
	return ids, nil
}

func (r *Repo) SetTrackCategories(ctx context.Context, trackID int64, categoryIDs []int64) error {
	if !r.Ready() {
		return errors.New("music repo not ready")
	}
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := tx.Where("track_id = ?", trackID).Delete(&categoryTrackRow{}).Error; err != nil {
			return err
		}
		now := time.Now().UTC()
		seen := map[int64]struct{}{}
		for _, cid := range categoryIDs {
			if cid <= 0 {
				continue
			}
			if _, ok := seen[cid]; ok {
				continue
			}
			seen[cid] = struct{}{}
			row := categoryTrackRow{CategoryID: cid, TrackID: trackID, CreatedAt: now}
			if err := tx.Create(&row).Error; err != nil {
				return err
			}
		}
		return nil
	})
}

func (r *Repo) attachCategoryIDs(ctx context.Context, tracks []entity.Track) ([]entity.Track, error) {
	if len(tracks) == 0 {
		return tracks, nil
	}
	ids := make([]int64, 0, len(tracks))
	for i := range tracks {
		ids = append(ids, tracks[i].ID)
	}
	var links []categoryTrackRow
	err := r.db.WithContext(ctx).Where("track_id IN ?", ids).Order("category_id ASC").Find(&links).Error
	if err != nil {
		return nil, err
	}
	m := map[int64][]int64{}
	for i := range links {
		l := &links[i]
		m[l.TrackID] = append(m[l.TrackID], l.CategoryID)
	}
	for i := range tracks {
		cats := m[tracks[i].ID]
		if cats == nil {
			cats = []int64{}
		}
		tracks[i].CategoryIDs = cats
	}
	return tracks, nil
}

func toEntity(row *trackRow) entity.Track {
	return entity.Track{
		ID:            row.ID,
		Title:         row.Title,
		CoverKey:      row.CoverKey,
		AudioKey:      row.AudioKey,
		BackgroundKey: row.BackgroundKey,
		CoverURL:      row.CoverURL,
		AudioURL:      row.AudioURL,
		BackgroundURL: row.BackgroundURL,
		RequireMember: row.RequireMember,
		SortOrder:     row.SortOrder,
		Enabled:       row.Enabled,
		CategoryIDs:   []int64{},
		CreatedAt:     row.CreatedAt,
		UpdatedAt:     row.UpdatedAt,
	}
}

func toCategoryEntity(row *categoryRow) entity.Category {
	return entity.Category{
		ID:        row.ID,
		ParentID:  row.ParentID,
		Name:      row.Name,
		SortOrder: row.SortOrder,
		Enabled:   row.Enabled,
		CreatedAt: row.CreatedAt,
		UpdatedAt: row.UpdatedAt,
	}
}