Project create limit (#148)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Introduced a daily limit for project creation, capping the number of
new projects a user can create per day.
- Added a new query endpoint that lets users check how many projects
they can still create today.
- Enhanced error notifications to clearly inform users when their daily
project creation limit has been reached.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

backend/src/project/project-limits.ts

@@ -0,0 +1,26 @@
+import { ForbiddenException, HttpStatus } from '@nestjs/common';
+import { GraphQLError } from 'graphql';
+
+export const PROJECT_DAILY_LIMIT = 3; // Maximum number of projects a user can create per day
+
+export enum ProjectErrorCode {
+  DAILY_LIMIT_EXCEEDED = 'DAILY_LIMIT_EXCEEDED',
+}
+
+export class ProjectRateLimitException extends ForbiddenException {
+  constructor(limit: number) {
+    super(
+      `Daily project creation limit of ${limit} reached. Please try again tomorrow.`,
+    );
+  }
+
+  getGraphQLError(): GraphQLError {
+    return new GraphQLError(this.message, {
+      extensions: {
+        code: ProjectErrorCode.DAILY_LIMIT_EXCEEDED,
+        limit: PROJECT_DAILY_LIMIT,
+        status: HttpStatus.TOO_MANY_REQUESTS,
+      },
+    });
+  }
+}

backend/src/project/project.resolver.ts

@@ -7,6 +7,7 @@ import {
   ResolveField,
   Parent,
   ID,
+  Int,
 } from '@nestjs/graphql';
 import { ProjectService } from './project.service';
 import { Project } from './project.model';
@@ -147,4 +148,12 @@ export class ProjectsResolver {
   ): Promise<Project[]> {
     return this.projectService.fetchPublicProjects(input);
   }
+
+  // In ProjectsResolver:
+  @Query(() => Int)
+  async getRemainingProjectLimit(
+    @GetUserIdFromToken() userId: string,
+  ): Promise<number> {
+    return this.projectService.getRemainingProjectLimit(userId);
+  }
 }

backend/src/project/project.service.ts

@@ -7,7 +7,7 @@ import {
   ForbiddenException,
 } from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
-import { In, Not, Repository } from 'typeorm';
+import { Between, In, Not, Repository } from 'typeorm';
 import { Project } from './project.model';
 import { ProjectPackages } from './project-packages.model';
 import {
@@ -26,6 +26,11 @@ import { BuilderContext } from 'src/build-system/context';
 import { ChatService } from 'src/chat/chat.service';
 import { Chat } from 'src/chat/chat.model';
 import { v4 as uuidv4 } from 'uuid';
+import {
+  PROJECT_DAILY_LIMIT,
+  ProjectRateLimitException,
+} from './project-limits';
+
 @Injectable()
 export class ProjectService {
   private readonly model: OpenAIModelProvider =
@@ -119,12 +124,41 @@ export class ProjectService {
     }
   }
 
+  /**
+   * Checks if a user has exceeded their daily project creation limit
+   * @param userId The user ID to check
+   * @returns A boolean indicating whether the user can create more projects today
+   */
+  async canCreateProject(userId: string): Promise<boolean> {
+    const today = new Date();
+    today.setHours(0, 0, 0, 0); // Start of today
+
+    const tomorrow = new Date(today);
+    tomorrow.setDate(tomorrow.getDate() + 1); // Start of tomorrow
+
+    // Count projects created by user today
+    const todayProjectCount = await this.projectsRepository.count({
+      where: {
+        userId: userId,
+        createdAt: Between(today, tomorrow),
+      },
+    });
+
+    return todayProjectCount < PROJECT_DAILY_LIMIT;
+  }
+
   async createProject(
     input: CreateProjectInput,
     userId: string,
   ): Promise<Chat> {
     try {
-      // First, handle project name generation if needed (this is the only sync operation we need)
+      //First check if user have reach the create project limit
+      const canCreate = await this.canCreateProject(userId);
+      if (!canCreate) {
+        throw new ProjectRateLimitException(PROJECT_DAILY_LIMIT);
+      }
+
+      // handle project name generation if needed (this is the only sync operation we need)
       let projectName = input.projectName;
       if (!projectName || projectName === '') {
         this.logger.debug(
@@ -164,6 +198,10 @@ export class ProjectService {
       // Return chat immediately so user can start interacting
       return defaultChat;
     } catch (error) {
+      if (error instanceof ProjectRateLimitException) {
+        throw error.getGraphQLError(); // Throw as a GraphQL error for the client
+      }
+
       this.logger.error(
         `Error in createProject: ${error.message}`,
         error.stack,
@@ -602,4 +640,27 @@ export class ProjectService {
 
     return [];
   }
+
+  /**
+   * Gets the number of projects a user can still create today
+   * @param userId The user ID to check
+   * @returns The number of remaining projects the user can create today
+   */
+  async getRemainingProjectLimit(userId: string): Promise<number> {
+    const today = new Date();
+    today.setHours(0, 0, 0, 0); // Start of today
+
+    const tomorrow = new Date(today);
+    tomorrow.setDate(tomorrow.getDate() + 1); // Start of tomorrow
+
+    // Count projects created by this user today
+    const todayProjectCount = await this.projectsRepository.count({
+      where: {
+        userId: userId,
+        createdAt: Between(today, tomorrow),
+      },
+    });
+
+    return Math.max(0, PROJECT_DAILY_LIMIT - todayProjectCount);
+  }
 }