openapi: 3.0.3
info: { title: Expense API, version: 1.0.0 }
servers: [ { url: https://your-domain.com/api/v1 } ]
tags: [ { name: Expenses } ]
security: [ { bearerAuth: [] } ]

paths:
  /expenses:
    get:
      tags: [Expenses]
      summary: List expenses
      parameters:
        - in: query
          name: page
          schema: { type: integer, default: 1 }
        - in: query
          name: per_page
          schema: { type: integer, default: 20 }
        - in: query
          name: status
          schema: { type: string }
        - in: query
          name: category
          schema: { type: string }
      responses:
        "200": { description: Expenses retrieved }
    post:
      tags: [Expenses]
      summary: Create expense
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required: [category, amount, description, date_of_purchase]
              properties:
                category: { type: string }
                amount: { type: number }
                description: { type: string }
                retailor: { type: string }
                date_of_purchase: { type: string, format: date }
                purchased_by: { type: integer }
                status: { type: string }
      responses:
        "201": { description: Expense created }

  /expenses/{id}:
    get:
      tags: [Expenses]
      summary: Get expense by ID
      parameters:
        - in: path
          name: id
          required: true
          schema: { type: integer }
      responses:
        "200": { description: Expense }
        "404": { description: Not found }
    put:
      tags: [Expenses]
      summary: Update expense
      parameters:
        - in: path
          name: id
          required: true
          schema: { type: integer }
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                category: { type: string }
                amount: { type: number }
                description: { type: string }
                retailor: { type: string }
                date_of_purchase: { type: string, format: date }
                status: { type: string }
                status_reason: { type: string }
      responses:
        "200": { description: Expense updated }
    delete:
      tags: [Expenses]
      summary: Delete expense
      parameters:
        - in: path
          name: id
          required: true
          schema: { type: integer }
      responses:
        "200": { description: Expense deleted }