samreshu_backend/tests/test-utils.ts

import { vi } from 'vitest';
import type { FastifyInstance } from 'fastify';
import type { NodePgDatabase } from 'drizzle-orm/node-postgres';
import type * as schema from '../src/db/schema/index.js';

export type MockDb = {
  select: ReturnType<NodePgDatabase<typeof schema>['select']>;
  insert: ReturnType<NodePgDatabase<typeof schema>['insert']>;
  update: ReturnType<NodePgDatabase<typeof schema>['update']>;
  delete: ReturnType<NodePgDatabase<typeof schema>['delete']>;
};

/** Build a select chain that resolves to the given rows at .limit(n) */
export function selectChain(resolveAtLimit: unknown[] = []) {
  const limitFn = vi.fn().mockResolvedValue(resolveAtLimit);
  return {
    from: vi.fn().mockReturnValue({
      where: vi.fn().mockReturnValue({
        limit: limitFn,
        orderBy: vi.fn().mockReturnValue({ limit: limitFn }),
      }),
      limit: limitFn,
    }),
  };
}

/** Build a select chain for .from().where().orderBy() - orderBy is terminal */
export function selectChainOrdered(resolveAtOrderBy: unknown[] = []) {
  const orderByThenable = {
    then: (resolve: (v: unknown) => void) => resolve(resolveAtOrderBy),
  };
  return {
    from: vi.fn().mockReturnValue({
      where: vi.fn().mockReturnValue({
        orderBy: vi.fn().mockReturnValue(orderByThenable),
      }),
    }),
  };
}

/** Build a select chain for .from().where() with no orderBy - used by select({...}).from() */
export function selectChainSimple(resolveRows: unknown[] = []) {
  const thenable = { then: (resolve: (v: unknown) => void) => resolve(resolveRows) };
  return {
    from: vi.fn().mockReturnValue({
      where: vi.fn().mockReturnValue(thenable),
    }),
  };
}

/** Build a select chain for .from().where() - where is terminal (no orderBy/limit) */
export function selectChainWhere(resolveAtWhere: unknown[] = []) {
  const thenable = { then: (resolve: (v: unknown) => void) => resolve(resolveAtWhere) };
  return {
    from: vi.fn().mockReturnValue({
      where: vi.fn().mockReturnValue(thenable),
    }),
  };
}

/** Build an insert chain that resolves at .returning() or .values() */
export function insertChain(resolveAtReturning: unknown[] = []) {
  const returningFn = vi.fn().mockResolvedValue(resolveAtReturning);
  const chainFromValues = {
    returning: returningFn,
    then: (resolve: (v?: unknown) => void) => resolve(undefined),
  };
  return {
    values: vi.fn().mockReturnValue(chainFromValues),
    returning: returningFn,
  };
}

/** Build an update chain that resolves at .where() */
export function updateChain(resolveAtWhere: unknown[] = []) {
  return {
    set: vi.fn().mockReturnValue({
      where: vi.fn().mockResolvedValue(resolveAtWhere),
    }),
  };
}

/** Build an update chain with .where().returning() */
export function updateChainReturning(resolveAtReturning: unknown[] = []) {
  const returningFn = vi.fn().mockResolvedValue(resolveAtReturning);
  return {
    set: vi.fn().mockReturnValue({
      where: vi.fn().mockReturnValue({
        returning: returningFn,
      }),
    }),
  };
}

/** Build a delete chain that resolves at .where() */
export function deleteChain() {
  return {
    where: vi.fn().mockResolvedValue(undefined),
  };
}

/**
 * Create a chainable mock for Drizzle DB operations.
 * Use mockReturnValue with selectChain/insertChain/updateChain/deleteChain.
 */
export function createMockDb(): MockDb {
  const chain = {
    from: vi.fn().mockReturnThis(),
    where: vi.fn().mockReturnThis(),
    values: vi.fn().mockReturnThis(),
    set: vi.fn().mockReturnThis(),
    orderBy: vi.fn().mockReturnThis(),
    limit: vi.fn().mockReturnThis(),
    returning: vi.fn().mockReturnThis(),
  };

  return {
    select: vi.fn().mockReturnValue(chain),
    insert: vi.fn().mockReturnValue(chain),
    update: vi.fn().mockReturnValue(chain),
    delete: vi.fn().mockReturnValue(chain),
  } as unknown as MockDb;
}

/**
 * Create a minimal mock Fastify app with db for route/integration tests.
 * Use buildApp() from app.ts for full integration tests.
 */
export function createMockApp(): FastifyInstance & { db: MockDb } {
  return {
    db: createMockDb(),
    log: {
      child: () => ({
        debug: () => {},
        info: () => {},
        warn: () => {},
        error: () => {},
        trace: () => {},
        fatal: () => {},
      }),
      debug: () => {},
      info: () => {},
      warn: () => {},
      error: () => {},
      trace: () => {},
      fatal: () => {},
    },
  } as FastifyInstance & { db: MockDb };
}