package repository

import (
	"context"

	"gorm.io/gorm"
)

func CountOrphanUserTenantMemberships(ctx context.Context, db *gorm.DB) (int64, error) {
	var count int64
	err := db.WithContext(ctx).Raw(`
SELECT COUNT(*)
FROM users AS u
WHERE u.deleted_at IS NULL
  AND (
	u.tenant_id IS NOT NULL
	AND NOT EXISTS (
		SELECT 1
		FROM tenants AS t
		WHERE t.id = u.tenant_id
		  AND t.deleted_at IS NULL
	)
  )
`).Scan(&count).Error
	return count, err
}

func ClearOrphanUserTenantMemberships(ctx context.Context, db *gorm.DB) (int64, error) {
	userResult := db.WithContext(ctx).Exec(`
WITH orphan_users AS (
	SELECT u.id AS user_id,
	       replacement.id AS replacement_tenant_id
	FROM users AS u
	JOIN tenants AS deleted_tenant
	  ON deleted_tenant.id = u.tenant_id
	 AND deleted_tenant.deleted_at IS NOT NULL
	JOIN LATERAL (
		WITH RECURSIVE ancestors AS (
			SELECT parent.id, parent.parent_id, parent.deleted_at, 1 AS depth
			FROM tenants AS parent
			WHERE parent.id = deleted_tenant.parent_id
			UNION ALL
			SELECT parent.id, parent.parent_id, parent.deleted_at, ancestors.depth + 1
			FROM tenants AS parent
			JOIN ancestors ON parent.id = ancestors.parent_id
			WHERE ancestors.parent_id IS NOT NULL
			  AND ancestors.parent_id <> ancestors.id
		)
		SELECT id
		FROM ancestors
		WHERE deleted_at IS NULL
		ORDER BY depth
		LIMIT 1
	) AS replacement ON true
	WHERE u.deleted_at IS NULL
	  AND u.tenant_id IS NOT NULL
)
UPDATE users AS u
SET tenant_id = ou.replacement_tenant_id,
	updated_at = NOW()
FROM orphan_users AS ou
WHERE u.id = ou.user_id
`)
	if userResult.Error != nil {
		return userResult.RowsAffected, userResult.Error
	}

	loginResult := db.WithContext(ctx).Exec(`
WITH orphan_login_ids AS (
	SELECT uli.id AS login_id,
	       replacement.id AS replacement_tenant_id
	FROM user_login_ids AS uli
	JOIN tenants AS deleted_tenant
	  ON deleted_tenant.id = uli.tenant_id
	 AND deleted_tenant.deleted_at IS NOT NULL
	JOIN LATERAL (
		WITH RECURSIVE ancestors AS (
			SELECT parent.id, parent.parent_id, parent.deleted_at, 1 AS depth
			FROM tenants AS parent
			WHERE parent.id = deleted_tenant.parent_id
			UNION ALL
			SELECT parent.id, parent.parent_id, parent.deleted_at, ancestors.depth + 1
			FROM tenants AS parent
			JOIN ancestors ON parent.id = ancestors.parent_id
			WHERE ancestors.parent_id IS NOT NULL
			  AND ancestors.parent_id <> ancestors.id
		)
		SELECT id
		FROM ancestors
		WHERE deleted_at IS NULL
		ORDER BY depth
		LIMIT 1
	) AS replacement ON true
)
UPDATE user_login_ids AS uli
SET tenant_id = oli.replacement_tenant_id
FROM orphan_login_ids AS oli
WHERE uli.id = oli.login_id
`)
	return userResult.RowsAffected + loginResult.RowsAffected, loginResult.Error
}