import { PrismaPg } from '@prisma/adapter-pg';

import { PrismaClient } from '@/lib/generated/prisma/client';

/**
 * The Prisma client, created on first use rather than on import.
 *
 * Next imports every route module while collecting page data at build time, in
 * a container that has no database and no DATABASE_URL. A module that threw on
 * import would fail the build with an error pointing at whichever route
 * happened to be analysed first, which says nothing useful. Creating the
 * client lazily moves that failure to the first actual query, where the
 * message is about the database because the problem is.
 */

const globalForPrisma = globalThis as unknown as { prisma?: PrismaClient };

function client(): PrismaClient {
  if (globalForPrisma.prisma) {
    return globalForPrisma.prisma;
  }

  const connectionString = process.env.DATABASE_URL;
  if (!connectionString) {
    throw new Error(
      'DATABASE_URL n’est pas défini : impossible de joindre la base de données.',
    );
  }

  const created = new PrismaClient({ adapter: new PrismaPg({ connectionString }) });

  // Next hot-reloads modules in development; without this the dev server would
  // open a new pool on every edit until Postgres refuses connections.
  if (process.env.NODE_ENV !== 'production') {
    globalForPrisma.prisma = created;
  }
  return created;
}

let singleton: PrismaClient | undefined;

function instance(): PrismaClient {
  singleton ??= client();
  return singleton;
}

export const prisma: PrismaClient = new Proxy({} as PrismaClient, {
  get(_target, property) {
    const target = instance();
    const value = Reflect.get(target, property) as unknown;
    // Model delegates and methods both need their original `this`.
    return typeof value === 'function' ? value.bind(target) : value;
  },
});