package tenant

import (
	"context"
	"fmt"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

// Registry kapselt den Zugriff auf die Control-Plane-Registry-Datenbank.
// Sie enthaelt ausschliesslich Tenant-Metadaten (Akzeptanzkriterium 1) —
// niemals Geschaeftsdaten eines Mandanten.
type Registry struct {
	pool *pgxpool.Pool
}

func NewRegistry(pool *pgxpool.Pool) *Registry {
	return &Registry{pool: pool}
}

// insertTx schreibt den Tenant-Datensatz innerhalb einer laufenden Transaktion,
// damit Provisioner.Provision DB-Anlage und Registrierung atomar behandeln kann.
func (r *Registry) insertTx(ctx context.Context, tx pgx.Tx, t Tenant) (Tenant, error) {
	row := tx.QueryRow(ctx, `
		INSERT INTO tenants (slug, name, db_name, db_dsn, status)
		VALUES ($1, $2, $3, $4, $5)
		RETURNING id, created_at
	`, t.Slug, t.Name, t.DBName, t.DBDSN, t.Status)

	if err := row.Scan(&t.ID, &t.CreatedAt); err != nil {
		return Tenant{}, fmt.Errorf("tenant registrieren: %w", err)
	}
	return t, nil
}

func (r *Registry) GetBySlug(ctx context.Context, slug string) (Tenant, error) {
	var t Tenant
	row := r.pool.QueryRow(ctx, `
		SELECT id, slug, name, db_name, db_dsn, status, created_at
		FROM tenants WHERE slug = $1
	`, slug)

	if err := row.Scan(&t.ID, &t.Slug, &t.Name, &t.DBName, &t.DBDSN, &t.Status, &t.CreatedAt); err != nil {
		return Tenant{}, fmt.Errorf("tenant laden: %w", err)
	}
	return t, nil
}

func (r *Registry) List(ctx context.Context) ([]Tenant, error) {
	rows, err := r.pool.Query(ctx, `
		SELECT id, slug, name, db_name, db_dsn, status, created_at
		FROM tenants ORDER BY created_at
	`)
	if err != nil {
		return nil, fmt.Errorf("tenants auflisten: %w", err)
	}
	defer rows.Close()

	var out []Tenant
	for rows.Next() {
		var t Tenant
		if err := rows.Scan(&t.ID, &t.Slug, &t.Name, &t.DBName, &t.DBDSN, &t.Status, &t.CreatedAt); err != nil {
			return nil, fmt.Errorf("tenant lesen: %w", err)
		}
		out = append(out, t)
	}
	return out, rows.Err()
}