openapi: 3.0.1
info:
  title: Simple Social Media API
  description: A basic Social Networking Service (SNS) API that allows users to create, retrieve, update, and delete posts; add comments; and like/unlike posts.
  version: 1.0.0
  contact:
    name: Contoso Product Team
    email: support@contoso.com
  license:
    name: MIT
    url: https://opensource.org/licenses/MIT

servers:
  - url: http://localhost:8080/api
    description: Local development server

paths:
  /posts:
    get:
      summary: List all posts
      description: Retrieve all recent posts to browse what others are sharing
      operationId: getPosts
      tags:
        - Posts
      responses:
        '200':
          description: Successfully retrieved posts
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Post'
        '500':
          $ref: '#/components/responses/InternalServerError'
    
    post:
      summary: Create a new post
      description: Create a new post to share something with others
      operationId: createPost
      tags:
        - Posts
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/NewPostRequest'
      responses:
        '201':
          description: Post created successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Post'
        '400':
          $ref: '#/components/responses/BadRequest'
        '500':
          $ref: '#/components/responses/InternalServerError'

  /posts/{postId}:
    get:
      summary: Get a specific post
      description: Retrieve a specific post by its ID to read in detail
      operationId: getPostById
      tags:
        - Posts
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
      responses:
        '200':
          description: Successfully retrieved the post
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Post'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
    
    patch:
      summary: Update a post
      description: Update an existing post if you made a mistake or have something to add
      operationId: updatePost
      tags:
        - Posts
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/UpdatePostRequest'
      responses:
        '200':
          description: Post updated successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Post'
        '400':
          $ref: '#/components/responses/BadRequest'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
    
    delete:
      summary: Delete a post
      description: Delete a post if you no longer want it shared
      operationId: deletePost
      tags:
        - Posts
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
      responses:
        '204':
          description: Post deleted successfully
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'

  /posts/{postId}/comments:
    get:
      summary: List comments for a post
      description: Retrieve all comments on a specific post
      operationId: getCommentsByPostId
      tags:
        - Comments
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
      responses:
        '200':
          description: Successfully retrieved comments
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Comment'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
    
    post:
      summary: Create a comment
      description: Add a comment to a post to share your thoughts
      operationId: createComment
      tags:
        - Comments
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/NewCommentRequest'
      responses:
        '201':
          description: Comment created successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Comment'
        '400':
          $ref: '#/components/responses/BadRequest'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'

  /posts/{postId}/comments/{commentId}:
    get:
      summary: Get a specific comment
      description: Retrieve a specific comment by its ID
      operationId: getCommentById
      tags:
        - Comments
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
        - $ref: '#/components/parameters/CommentIdPath'
      responses:
        '200':
          description: Successfully retrieved the comment
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Comment'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
    
    patch:
      summary: Update a comment
      description: Update an existing comment to correct or revise it
      operationId: updateComment
      tags:
        - Comments
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
        - $ref: '#/components/parameters/CommentIdPath'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/UpdateCommentRequest'
      responses:
        '200':
          description: Comment updated successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Comment'
        '400':
          $ref: '#/components/responses/BadRequest'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
    
    delete:
      summary: Delete a comment
      description: Delete a comment if necessary
      operationId: deleteComment
      tags:
        - Comments
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
        - $ref: '#/components/parameters/CommentIdPath'
      responses:
        '204':
          description: Comment deleted successfully
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'

  /posts/{postId}/likes:
    post:
      summary: Like a post
      description: Like a post to show appreciation
      operationId: likePost
      tags:
        - Likes
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/LikeRequest'
      responses:
        '201':
          description: Post liked successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/LikeResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
    
    delete:
      summary: Unlike a post
      description: Remove your like from a post if you change your mind
      operationId: unlikePost
      tags:
        - Likes
      parameters:
        - $ref: '#/components/parameters/PostIdPath'
      responses:
        '204':
          description: Like removed successfully
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'

components:
  parameters:
    PostIdPath:
      name: postId
      in: path
      required: true
      description: Unique identifier of the post
      schema:
        type: string
        format: uuid
        example: "123e4567-e89b-12d3-a456-426614174000"
    
    CommentIdPath:
      name: commentId
      in: path
      required: true
      description: Unique identifier of the comment
      schema:
        type: string
        format: uuid
        example: "987fcdeb-51a2-43d1-9f6b-123456789abc"

  schemas:
    Post:
      type: object
      required:
        - id
        - username
        - content
        - createdAt
        - updatedAt
        - likesCount
        - commentsCount
      properties:
        id:
          type: string
          format: uuid
          description: Unique identifier for the post
          example: "123e4567-e89b-12d3-a456-426614174000"
        username:
          type: string
          minLength: 1
          maxLength: 50
          description: Username of the post author
          example: "john_doe"
        content:
          type: string
          minLength: 1
          maxLength: 2000
          description: Content of the post
          example: "Just had an amazing hike in the mountains! #outdoorlife"
        createdAt:
          type: string
          format: date-time
          description: Timestamp when the post was created
          example: "2025-06-01T10:30:00Z"
        updatedAt:
          type: string
          format: date-time
          description: Timestamp when the post was last updated
          example: "2025-06-01T10:30:00Z"
        likesCount:
          type: integer
          minimum: 0
          description: Number of likes on the post
          example: 15
        commentsCount:
          type: integer
          minimum: 0
          description: Number of comments on the post
          example: 3

    Comment:
      type: object
      required:
        - id
        - postId
        - username
        - content
        - createdAt
        - updatedAt
      properties:
        id:
          type: string
          format: uuid
          description: Unique identifier for the comment
          example: "987fcdeb-51a2-43d1-9f6b-123456789abc"
        postId:
          type: string
          format: uuid
          description: ID of the post this comment belongs to
          example: "123e4567-e89b-12d3-a456-426614174000"
        username:
          type: string
          minLength: 1
          maxLength: 50
          description: Username of the comment author
          example: "jane_smith"
        content:
          type: string
          minLength: 1
          maxLength: 1000
          description: Content of the comment
          example: "Great photo! Where was this taken?"
        createdAt:
          type: string
          format: date-time
          description: Timestamp when the comment was created
          example: "2025-06-01T11:15:00Z"
        updatedAt:
          type: string
          format: date-time
          description: Timestamp when the comment was last updated
          example: "2025-06-01T11:15:00Z"

    NewPostRequest:
      type: object
      required:
        - username
        - content
      properties:
        username:
          type: string
          minLength: 1
          maxLength: 50
          description: Username of the post author
          example: "john_doe"
        content:
          type: string
          minLength: 1
          maxLength: 2000
          description: Content of the post
          example: "Just had an amazing hike in the mountains! #outdoorlife"

    UpdatePostRequest:
      type: object
      required:
        - username
        - content
      properties:
        username:
          type: string
          minLength: 1
          maxLength: 50
          description: Username of the post author (for validation)
          example: "john_doe"
        content:
          type: string
          minLength: 1
          maxLength: 2000
          description: Updated content of the post
          example: "Just had an amazing hike in the mountains! The view was breathtaking. #outdoorlife #hiking"

    NewCommentRequest:
      type: object
      required:
        - username
        - content
      properties:
        username:
          type: string
          minLength: 1
          maxLength: 50
          description: Username of the comment author
          example: "jane_smith"
        content:
          type: string
          minLength: 1
          maxLength: 1000
          description: Content of the comment
          example: "Great photo! Where was this taken?"

    UpdateCommentRequest:
      type: object
      required:
        - username
        - content
      properties:
        username:
          type: string
          minLength: 1
          maxLength: 50
          description: Username of the comment author (for validation)
          example: "jane_smith"
        content:
          type: string
          minLength: 1
          maxLength: 1000
          description: Updated content of the comment
          example: "Great photo! Where was this taken? The scenery looks amazing!"

    LikeRequest:
      type: object
      required:
        - username
      properties:
        username:
          type: string
          minLength: 1
          maxLength: 50
          description: Username of the user liking the post
          example: "mike_wilson"

    LikeResponse:
      type: object
      required:
        - postId
        - username
        - likedAt
      properties:
        postId:
          type: string
          format: uuid
          description: ID of the liked post
          example: "123e4567-e89b-12d3-a456-426614174000"
        username:
          type: string
          description: Username who liked the post
          example: "mike_wilson"
        likedAt:
          type: string
          format: date-time
          description: Timestamp when the post was liked
          example: "2025-06-01T12:00:00Z"

    Error:
      type: object
      required:
        - error
        - message
      properties:
        error:
          type: string
          description: Error code or type
          example: "VALIDATION_ERROR"
        message:
          type: string
          description: Human-readable error message
          example: "The request body is invalid"
        details:
          type: array
          description: Additional error details (optional)
          items:
            type: string
          example: ["username is required", "content must not be empty"]

  responses:
    BadRequest:
      description: Bad request - invalid input or validation error
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error: "VALIDATION_ERROR"
            message: "The request body is invalid"
            details: ["username is required", "content must not be empty"]

    NotFound:
      description: Resource not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error: "NOT_FOUND"
            message: "The requested resource was not found"

    InternalServerError:
      description: Internal server error
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error: "INTERNAL_ERROR"
            message: "An unexpected error occurred"

tags:
  - name: Posts
    description: Operations related to posts management
  - name: Comments
    description: Operations related to comments management
  - name: Likes
    description: Operations related to likes management