openapi: 3.0.1
info:
  title: Simple Social Media Application 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: Product Owner / Tech Lead at Contoso
  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 for browsing
      operationId: listPosts
      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 with others
      operationId: createPost
      tags:
        - Posts
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreatePostRequest'
      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}:
    parameters:
      - $ref: '#/components/parameters/PostId'
    
    get:
      summary: Get a specific post
      description: Retrieve a specific post by its ID
      operationId: getPost
      tags:
        - Posts
      responses:
        '200':
          description: Successfully retrieved 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 content
      operationId: updatePost
      tags:
        - Posts
      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 specific post
      operationId: deletePost
      tags:
        - Posts
      responses:
        '204':
          description: Post deleted successfully
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'

  /posts/{postId}/comments:
    parameters:
      - $ref: '#/components/parameters/PostId'
    
    get:
      summary: List comments for a post
      description: Retrieve all comments for a specific post
      operationId: listComments
      tags:
        - Comments
      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 new comment to a post
      operationId: createComment
      tags:
        - Comments
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateCommentRequest'
      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}:
    parameters:
      - $ref: '#/components/parameters/PostId'
      - $ref: '#/components/parameters/CommentId'
    
    get:
      summary: Get a specific comment
      description: Retrieve a specific comment by its ID
      operationId: getComment
      tags:
        - Comments
      responses:
        '200':
          description: Successfully retrieved 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
      operationId: updateComment
      tags:
        - Comments
      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 specific comment
      operationId: deleteComment
      tags:
        - Comments
      responses:
        '204':
          description: Comment deleted successfully
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'

  /posts/{postId}/likes:
    parameters:
      - $ref: '#/components/parameters/PostId'
    
    post:
      summary: Like a post
      description: Add a like to a specific post
      operationId: likePost
      tags:
        - Likes
      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 a like from a specific post
      operationId: unlikePost
      tags:
        - Likes
      parameters:
        - name: username
          in: query
          required: true
          description: Username of the user removing the like
          schema:
            type: string
            minLength: 1
            maxLength: 50
      responses:
        '204':
          description: Post unliked successfully
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'

components:
  parameters:
    PostId:
      name: postId
      in: path
      required: true
      description: Unique identifier for a post
      schema:
        type: string
        format: uuid
    
    CommentId:
      name: commentId
      in: path
      required: true
      description: Unique identifier for a comment
      schema:
        type: string
        format: uuid

  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: 1000
          description: Content of the post
          example: "Just had an amazing hiking experience with Contoso gear!"
        createdAt:
          type: string
          format: date-time
          description: Timestamp when the post was created
          example: "2025-05-30T10:30:00Z"
        updatedAt:
          type: string
          format: date-time
          description: Timestamp when the post was last updated
          example: "2025-05-30T10:30:00Z"
        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: "456e7890-e89b-12d3-a456-426614174001"
        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: 500
          description: Content of the comment
          example: "Great post! I love their outdoor equipment too."
        createdAt:
          type: string
          format: date-time
          description: Timestamp when the comment was created
          example: "2025-05-30T11:15:00Z"
        updatedAt:
          type: string
          format: date-time
          description: Timestamp when the comment was last updated
          example: "2025-05-30T11:15:00Z"

    CreatePostRequest:
      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: 1000
          description: Content of the post
          example: "Just had an amazing hiking experience with Contoso gear!"

    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: 1000
          description: Updated content of the post
          example: "Just had an amazing hiking experience with Contoso gear! Highly recommend their backpacks."

    CreateCommentRequest:
      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: 500
          description: Content of the comment
          example: "Great post! I love their outdoor equipment too."

    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: 500
          description: Updated content of the comment
          example: "Great post! I love their outdoor equipment too. Where did you buy it?"

    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 of the user who liked the post
          example: "mike_wilson"
        likedAt:
          type: string
          format: date-time
          description: Timestamp when the like was added
          example: "2025-05-30T12:00:00Z"

    ErrorResponse:
      type: object
      required:
        - error
        - message
      properties:
        error:
          type: string
          description: Error type
          example: "BadRequest"
        message:
          type: string
          description: Human-readable error message
          example: "The request is invalid or missing required fields"
        details:
          type: object
          description: Additional error details
          additionalProperties: true

  responses:
    BadRequest:
      description: Bad request - Invalid input or missing required fields
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
          example:
            error: "BadRequest"
            message: "The request is invalid or missing required fields"
            details:
              field: "username"
              issue: "Username is required and cannot be empty"

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

    InternalServerError:
      description: Internal server error
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
          example:
            error: "InternalServerError"
            message: "An unexpected error occurred while processing the request"

tags:
  - name: Posts
    description: Operations related to post management
  - name: Comments
    description: Operations related to comment management
  - name: Likes
    description: Operations related to post likes