package services

import (
	"context"
	"fmt"
	"time"

	"github.com/google/uuid"
	"go.uber.org/zap"
	"gorm.io/gorm"
)

// AdminPlatformService provides platform administration capabilities (F421-F435)
type AdminPlatformService struct {
	db     *gorm.DB
	logger *zap.Logger
}

// NewAdminPlatformService creates a new admin platform service
func NewAdminPlatformService(db *gorm.DB, logger *zap.Logger) *AdminPlatformService {
	if logger == nil {
		logger = zap.NewNop()
	}
	return &AdminPlatformService{db: db, logger: logger}
}

// --- F421: Platform Dashboard Metrics ---

// PlatformMetrics contains platform-wide statistics
type PlatformMetrics struct {
	TotalUsers       int64   `json:"total_users"`
	ActiveUsers      int64   `json:"active_users"`
	NewUsersToday    int64   `json:"new_users_today"`
	NewUsersWeek     int64   `json:"new_users_week"`
	TotalTracks      int64   `json:"total_tracks"`
	TracksToday      int64   `json:"tracks_today"`
	TotalPlaylists   int64   `json:"total_playlists"`
	TotalComments    int64   `json:"total_comments"`
	BannedUsers      int64   `json:"banned_users"`
	PendingReports   int64   `json:"pending_reports"`
	StorageUsedMB    float64 `json:"storage_used_mb"`
	TotalRevenue     float64 `json:"total_revenue"`
	RevenueThisMonth float64 `json:"revenue_this_month"`
}

// GetPlatformMetrics returns platform-wide metrics (F421)
func (s *AdminPlatformService) GetPlatformMetrics(ctx context.Context) (*PlatformMetrics, error) {
	m := &PlatformMetrics{}
	now := time.Now()
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	weekAgo := today.AddDate(0, 0, -7)
	monthStart := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())

	// User counts
	s.db.WithContext(ctx).Table("users").Where("deleted_at IS NULL").Count(&m.TotalUsers)
	s.db.WithContext(ctx).Table("users").Where("deleted_at IS NULL AND last_login_at > NOW() - INTERVAL '30 days'").Count(&m.ActiveUsers)
	s.db.WithContext(ctx).Table("users").Where("deleted_at IS NULL AND created_at >= ?", today).Count(&m.NewUsersToday)
	s.db.WithContext(ctx).Table("users").Where("deleted_at IS NULL AND created_at >= ?", weekAgo).Count(&m.NewUsersWeek)
	s.db.WithContext(ctx).Table("users").Where("deleted_at IS NULL AND is_banned = TRUE").Count(&m.BannedUsers)

	// Content counts
	s.db.WithContext(ctx).Table("tracks").Where("deleted_at IS NULL").Count(&m.TotalTracks)
	s.db.WithContext(ctx).Table("tracks").Where("deleted_at IS NULL AND created_at >= ?", today).Count(&m.TracksToday)
	s.db.WithContext(ctx).Table("playlists").Where("deleted_at IS NULL").Count(&m.TotalPlaylists)
	s.db.WithContext(ctx).Table("comments").Where("deleted_at IS NULL").Count(&m.TotalComments)

	// Reports
	s.db.WithContext(ctx).Table("reports").Where("status = 'pending'").Count(&m.PendingReports)

	// Storage (approximate from tracks file sizes)
	var storageBytesRaw *int64
	s.db.WithContext(ctx).Raw("SELECT SUM(file_size) FROM tracks WHERE deleted_at IS NULL").Scan(&storageBytesRaw)
	if storageBytesRaw != nil {
		m.StorageUsedMB = float64(*storageBytesRaw) / (1024 * 1024)
	}

	// Revenue (from orders)
	var totalRevRaw *float64
	s.db.WithContext(ctx).Raw("SELECT COALESCE(SUM(total_amount), 0) FROM orders WHERE status = 'completed'").Scan(&totalRevRaw)
	if totalRevRaw != nil {
		m.TotalRevenue = *totalRevRaw
	}

	var monthRevRaw *float64
	s.db.WithContext(ctx).Raw("SELECT COALESCE(SUM(total_amount), 0) FROM orders WHERE status = 'completed' AND created_at >= ?", monthStart).Scan(&monthRevRaw)
	if monthRevRaw != nil {
		m.RevenueThisMonth = *monthRevRaw
	}

	return m, nil
}

// --- F422: User Management ---

// AdminUserInfo represents a user as seen by admin
type AdminUserInfo struct {
	ID            string     `json:"id"`
	Username      string     `json:"username"`
	Email         string     `json:"email"`
	Role          string     `json:"role"`
	IsActive      bool       `json:"is_active"`
	IsBanned      bool       `json:"is_banned"`
	IsVerified    bool       `json:"is_verified"`
	IsAdmin       bool       `json:"is_admin"`
	TrackCount    int64      `json:"track_count"`
	LoginCount    int        `json:"login_count"`
	LastLoginAt   *time.Time `json:"last_login_at,omitempty"`
	CreatedAt     time.Time  `json:"created_at"`
	ActiveStrikes int64      `json:"active_strikes"`
	IsSuspended   bool       `json:"is_suspended"`
}

// AdminUserSearchParams holds search/filter parameters for user management
type AdminUserSearchParams struct {
	Query    string // search username/email
	Role     string
	IsBanned *bool
	Limit    int
	Offset   int
	SortBy   string // "created_at", "username", "last_login_at"
}

// SearchUsers searches and lists users for admin management (F422)
func (s *AdminPlatformService) SearchUsers(ctx context.Context, params AdminUserSearchParams) ([]AdminUserInfo, int64, error) {
	if params.Limit <= 0 {
		params.Limit = 20
	}
	if params.Limit > 100 {
		params.Limit = 100
	}

	query := s.db.WithContext(ctx).Table("users").Where("users.deleted_at IS NULL")

	if params.Query != "" {
		like := "%" + params.Query + "%"
		query = query.Where("(username ILIKE ? OR email ILIKE ?)", like, like)
	}
	if params.Role != "" {
		query = query.Where("role = ?", params.Role)
	}
	if params.IsBanned != nil {
		query = query.Where("is_banned = ?", *params.IsBanned)
	}

	var total int64
	query.Count(&total)

	orderBy := "created_at DESC"
	switch params.SortBy {
	case "username":
		orderBy = "username ASC"
	case "last_login_at":
		orderBy = "last_login_at DESC NULLS LAST"
	}

	var rows []struct {
		ID          uuid.UUID  `gorm:"column:id"`
		Username    string     `gorm:"column:username"`
		Email       string     `gorm:"column:email"`
		Role        string     `gorm:"column:role"`
		IsActive    bool       `gorm:"column:is_active"`
		IsBanned    bool       `gorm:"column:is_banned"`
		IsVerified  bool       `gorm:"column:is_verified"`
		IsAdmin     bool       `gorm:"column:is_admin"`
		LoginCount  int        `gorm:"column:login_count"`
		LastLoginAt *time.Time `gorm:"column:last_login_at"`
		CreatedAt   time.Time  `gorm:"column:created_at"`
	}

	if err := query.Select("id, username, email, role, is_active, is_banned, is_verified, is_admin, login_count, last_login_at, created_at").
		Order(orderBy).Offset(params.Offset).Limit(params.Limit).Scan(&rows).Error; err != nil {
		return nil, 0, fmt.Errorf("failed to search users: %w", err)
	}

	users := make([]AdminUserInfo, len(rows))
	for i, r := range rows {
		users[i] = AdminUserInfo{
			ID:          r.ID.String(),
			Username:    r.Username,
			Email:       r.Email,
			Role:        r.Role,
			IsActive:    r.IsActive,
			IsBanned:    r.IsBanned,
			IsVerified:  r.IsVerified,
			IsAdmin:     r.IsAdmin,
			LoginCount:  r.LoginCount,
			LastLoginAt: r.LastLoginAt,
			CreatedAt:   r.CreatedAt,
		}

		// Track count
		s.db.WithContext(ctx).Table("tracks").Where("creator_id = ? AND deleted_at IS NULL", r.ID).Count(&users[i].TrackCount)

		// Active strikes
		s.db.WithContext(ctx).Table("user_strikes").Where("user_id = ? AND is_active = TRUE", r.ID).Count(&users[i].ActiveStrikes)

		// Suspension
		var suspCount int64
		s.db.WithContext(ctx).Table("user_suspensions").Where("user_id = ? AND is_active = TRUE", r.ID).Count(&suspCount)
		users[i].IsSuspended = suspCount > 0
	}

	return users, total, nil
}

// GetUserDetail returns detailed user info for admin view (F422)
func (s *AdminPlatformService) GetUserDetail(ctx context.Context, userID uuid.UUID) (*AdminUserInfo, error) {
	var r struct {
		ID          uuid.UUID  `gorm:"column:id"`
		Username    string     `gorm:"column:username"`
		Email       string     `gorm:"column:email"`
		Role        string     `gorm:"column:role"`
		IsActive    bool       `gorm:"column:is_active"`
		IsBanned    bool       `gorm:"column:is_banned"`
		IsVerified  bool       `gorm:"column:is_verified"`
		IsAdmin     bool       `gorm:"column:is_admin"`
		LoginCount  int        `gorm:"column:login_count"`
		LastLoginAt *time.Time `gorm:"column:last_login_at"`
		CreatedAt   time.Time  `gorm:"column:created_at"`
	}

	if err := s.db.WithContext(ctx).Table("users").Where("id = ? AND deleted_at IS NULL", userID).First(&r).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, fmt.Errorf("user not found")
		}
		return nil, fmt.Errorf("failed to get user: %w", err)
	}

	user := &AdminUserInfo{
		ID:          r.ID.String(),
		Username:    r.Username,
		Email:       r.Email,
		Role:        r.Role,
		IsActive:    r.IsActive,
		IsBanned:    r.IsBanned,
		IsVerified:  r.IsVerified,
		IsAdmin:     r.IsAdmin,
		LoginCount:  r.LoginCount,
		LastLoginAt: r.LastLoginAt,
		CreatedAt:   r.CreatedAt,
	}

	s.db.WithContext(ctx).Table("tracks").Where("creator_id = ? AND deleted_at IS NULL", userID).Count(&user.TrackCount)
	s.db.WithContext(ctx).Table("user_strikes").Where("user_id = ? AND is_active = TRUE", userID).Count(&user.ActiveStrikes)

	var suspCount int64
	s.db.WithContext(ctx).Table("user_suspensions").Where("user_id = ? AND is_active = TRUE", userID).Count(&suspCount)
	user.IsSuspended = suspCount > 0

	return user, nil
}

// UpdateUserRole updates a user's role (F422)
func (s *AdminPlatformService) UpdateUserRole(ctx context.Context, userID uuid.UUID, newRole string) error {
	validRoles := map[string]bool{"user": true, "creator": true, "premium": true, "admin": true, "artist": true, "producer": true, "label": true}
	if !validRoles[newRole] {
		return fmt.Errorf("invalid role: %s", newRole)
	}

	result := s.db.WithContext(ctx).Table("users").Where("id = ? AND deleted_at IS NULL", userID).Update("role", newRole)
	if result.Error != nil {
		return fmt.Errorf("failed to update role: %w", result.Error)
	}
	if result.RowsAffected == 0 {
		return fmt.Errorf("user not found")
	}

	isAdmin := newRole == "admin"
	s.db.WithContext(ctx).Table("users").Where("id = ?", userID).Update("is_admin", isAdmin)

	return nil
}

// SuspendUser suspends a user (F422)
func (s *AdminPlatformService) SuspendUser(ctx context.Context, userID uuid.UUID, adminID uuid.UUID, reason string, durationDays *int) error {
	return s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var suspendedUntil *time.Time
		if durationDays != nil {
			t := time.Now().AddDate(0, 0, *durationDays)
			suspendedUntil = &t
		}

		if err := tx.Exec(`
			INSERT INTO user_suspensions (user_id, reason, suspended_by, suspended_until)
			VALUES (?, ?, ?, ?)
		`, userID, reason, adminID, suspendedUntil).Error; err != nil {
			return fmt.Errorf("failed to create suspension: %w", err)
		}

		if err := tx.Table("users").Where("id = ?", userID).Update("is_banned", true).Error; err != nil {
			return fmt.Errorf("failed to ban user: %w", err)
		}

		// Log moderation action
		tx.Exec(`INSERT INTO moderation_actions (moderator_id, target_user_id, action, reason) VALUES (?, ?, 'suspend', ?)`,
			adminID, userID, reason)

		return nil
	})
}

// UnsuspendUser lifts a user's suspension (F422)
func (s *AdminPlatformService) UnsuspendUser(ctx context.Context, userID uuid.UUID, adminID uuid.UUID) error {
	return s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		now := time.Now()
		tx.Exec(`UPDATE user_suspensions SET is_active = FALSE, lifted_by = ?, lifted_at = ? WHERE user_id = ? AND is_active = TRUE`,
			adminID, now, userID)

		if err := tx.Table("users").Where("id = ?", userID).Update("is_banned", false).Error; err != nil {
			return fmt.Errorf("failed to unban user: %w", err)
		}

		tx.Exec(`INSERT INTO moderation_actions (moderator_id, target_user_id, action, reason) VALUES (?, ?, 'unsuspend', 'Manual unsuspension by admin')`,
			adminID, userID)

		return nil
	})
}

// --- F423: Content Management ---

// AdminContentItem represents a content item for admin management
type AdminContentItem struct {
	ID          string    `json:"id"`
	Type        string    `json:"type"` // "track" or "comment"
	Title       string    `json:"title"`
	CreatorID   string    `json:"creator_id"`
	CreatorName string    `json:"creator_name"`
	Status      string    `json:"status"`
	ReportCount int64     `json:"report_count"`
	CreatedAt   time.Time `json:"created_at"`
}

// SearchContent searches content for admin management (F423)
func (s *AdminPlatformService) SearchContent(ctx context.Context, contentType, query string, limit, offset int) ([]AdminContentItem, int64, error) {
	if limit <= 0 {
		limit = 20
	}
	if limit > 100 {
		limit = 100
	}

	var items []AdminContentItem
	var total int64

	switch contentType {
	case "track", "":
		baseQuery := s.db.WithContext(ctx).Table("tracks t").
			Select(`CAST(t.id AS TEXT) AS id, 'track' AS type, t.title, CAST(t.creator_id AS TEXT) AS creator_id,
					u.username AS creator_name,
					CASE WHEN t.deleted_at IS NOT NULL THEN 'hidden' ELSE 'active' END AS status,
					t.created_at`).
			Joins("LEFT JOIN users u ON u.id = t.creator_id")

		if query != "" {
			like := "%" + query + "%"
			baseQuery = baseQuery.Where("t.title ILIKE ?", like)
		}

		s.db.WithContext(ctx).Table("tracks").Count(&total)
		if query != "" {
			s.db.WithContext(ctx).Table("tracks").Where("title ILIKE ?", "%"+query+"%").Count(&total)
		}

		var rows []AdminContentItem
		if err := baseQuery.Order("t.created_at DESC").Offset(offset).Limit(limit).Scan(&rows).Error; err != nil {
			return nil, 0, fmt.Errorf("failed to search tracks: %w", err)
		}

		// Add report counts
		for i, row := range rows {
			var rc int64
			s.db.WithContext(ctx).Table("reports").Where("content_type = 'track' AND CAST(content_id AS TEXT) = ? AND status = 'pending'", row.ID).Count(&rc)
			rows[i].ReportCount = rc
		}
		items = rows

	case "comment":
		baseQuery := s.db.WithContext(ctx).Table("comments c").
			Select(`CAST(c.id AS TEXT) AS id, 'comment' AS type, LEFT(c.content, 100) AS title,
					CAST(c.user_id AS TEXT) AS creator_id, u.username AS creator_name,
					CASE WHEN c.deleted_at IS NOT NULL THEN 'hidden' ELSE 'active' END AS status,
					c.created_at`).
			Joins("LEFT JOIN users u ON u.id = c.user_id")

		if query != "" {
			like := "%" + query + "%"
			baseQuery = baseQuery.Where("c.content ILIKE ?", like)
		}

		s.db.WithContext(ctx).Table("comments").Count(&total)
		if query != "" {
			s.db.WithContext(ctx).Table("comments").Where("content ILIKE ?", "%"+query+"%").Count(&total)
		}

		if err := baseQuery.Order("c.created_at DESC").Offset(offset).Limit(limit).Scan(&items).Error; err != nil {
			return nil, 0, fmt.Errorf("failed to search comments: %w", err)
		}
	}

	return items, total, nil
}

// HideContent hides (soft deletes) content by admin (F423)
func (s *AdminPlatformService) HideContent(ctx context.Context, adminID uuid.UUID, contentType string, contentID uuid.UUID, reason string) error {
	now := time.Now()
	var err error

	switch contentType {
	case "track":
		err = s.db.WithContext(ctx).Table("tracks").Where("id = ? AND deleted_at IS NULL", contentID).Update("deleted_at", now).Error
	case "comment":
		err = s.db.WithContext(ctx).Table("comments").Where("id = ? AND deleted_at IS NULL", contentID).Update("deleted_at", now).Error
	default:
		return fmt.Errorf("invalid content type: %s", contentType)
	}

	if err != nil {
		return fmt.Errorf("failed to hide content: %w", err)
	}

	// Log moderation action
	s.db.WithContext(ctx).Exec(`
		INSERT INTO moderation_actions (moderator_id, target_content_type, target_content_id, action, reason)
		VALUES (?, ?, ?, 'hide_content', ?)
	`, adminID, contentType, contentID, reason)

	return nil
}

// RestoreContent restores hidden content (F423)
func (s *AdminPlatformService) RestoreContent(ctx context.Context, adminID uuid.UUID, contentType string, contentID uuid.UUID) error {
	var err error

	switch contentType {
	case "track":
		err = s.db.WithContext(ctx).Exec("UPDATE tracks SET deleted_at = NULL WHERE id = ?", contentID).Error
	case "comment":
		err = s.db.WithContext(ctx).Exec("UPDATE comments SET deleted_at = NULL WHERE id = ?", contentID).Error
	default:
		return fmt.Errorf("invalid content type: %s", contentType)
	}

	if err != nil {
		return fmt.Errorf("failed to restore content: %w", err)
	}

	s.db.WithContext(ctx).Exec(`
		INSERT INTO moderation_actions (moderator_id, target_content_type, target_content_id, action, reason)
		VALUES (?, ?, ?, 'restore_content', 'Admin restored content')
	`, adminID, contentType, contentID)

	return nil
}

// --- F424: Payment Overview ---

// PaymentOverview contains payment/revenue overview
type PaymentOverview struct {
	TotalOrders     int64   `json:"total_orders"`
	CompletedOrders int64   `json:"completed_orders"`
	PendingOrders   int64   `json:"pending_orders"`
	RefundedOrders  int64   `json:"refunded_orders"`
	TotalRevenue    float64 `json:"total_revenue"`
	TotalRefunded   float64 `json:"total_refunded"`
	PlatformFees    float64 `json:"platform_fees"`
}

// GetPaymentOverview returns payment statistics (F424)
func (s *AdminPlatformService) GetPaymentOverview(ctx context.Context) (*PaymentOverview, error) {
	overview := &PaymentOverview{}

	s.db.WithContext(ctx).Table("orders").Count(&overview.TotalOrders)
	s.db.WithContext(ctx).Table("orders").Where("status = 'completed'").Count(&overview.CompletedOrders)
	s.db.WithContext(ctx).Table("orders").Where("status = 'pending'").Count(&overview.PendingOrders)
	s.db.WithContext(ctx).Table("orders").Where("status = 'refunded'").Count(&overview.RefundedOrders)

	var totalRev *float64
	s.db.WithContext(ctx).Raw("SELECT COALESCE(SUM(total_amount), 0) FROM orders WHERE status = 'completed'").Scan(&totalRev)
	if totalRev != nil {
		overview.TotalRevenue = *totalRev
	}

	var totalRefund *float64
	s.db.WithContext(ctx).Raw("SELECT COALESCE(SUM(total_amount), 0) FROM orders WHERE status = 'refunded'").Scan(&totalRefund)
	if totalRefund != nil {
		overview.TotalRefunded = *totalRefund
	}

	var fees *float64
	s.db.WithContext(ctx).Raw("SELECT COALESCE(SUM(platform_fee), 0) FROM orders WHERE status = 'completed'").Scan(&fees)
	if fees != nil {
		overview.PlatformFees = *fees
	}

	return overview, nil
}

// RefundOrder marks an order as refunded (F424)
// In production this would also call the payment gateway. For now it records the intent.
func (s *AdminPlatformService) RefundOrder(ctx context.Context, adminID uuid.UUID, orderID uuid.UUID, reason string) error {
	result := s.db.WithContext(ctx).Table("orders").Where("id = ? AND status = 'completed'", orderID).Updates(map[string]interface{}{
		"status":     "refunded",
		"updated_at": time.Now(),
	})
	if result.Error != nil {
		return fmt.Errorf("failed to refund order: %w", result.Error)
	}
	if result.RowsAffected == 0 {
		return fmt.Errorf("order not found or not eligible for refund")
	}

	// Log the refund action
	s.db.WithContext(ctx).Exec(`
		INSERT INTO moderation_actions (moderator_id, target_content_type, target_content_id, action, reason)
		VALUES (?, 'order', ?, 'refund', ?)
	`, adminID, orderID, reason)

	return nil
}