openapi: 3.1.0
info:
  title: Getraenkeautomat Monitor API
  version: 1.0.0
  summary: HTTP API for ingesting sensor readings and retrieving vending machine status.
  description: |
    Handwritten OpenAPI specification for the Getraenkeautomat Monitor application.

    The API currently exposes two endpoints:
    - `POST /api/v1/readings.php` for ingesting one sensor measurement
    - `GET /api/v1/status.php` for retrieving the aggregated application state

    The readings endpoint uses Bearer token authentication. The status endpoint is
    intentionally public so the dashboard can poll it without a login.
servers:
  - url: ./
    description: Same-origin deployment
tags:
  - name: Readings
    description: Receive one sensor reading and update the persisted slot state.
  - name: Status
    description: Retrieve the current aggregated machine, slot, and alert status.
paths:
  /api/v1/readings.php:
    post:
      tags:
        - Readings
      summary: Submit one reading
      description: |
        Accepts exactly one sensor measurement for one configured machine slot.

        Processing behavior:
        - Requires a Bearer token in the `Authorization` header
        - Accepts JSON request bodies
        - Updates `data/state.json` on success
        - Triggers alerts only when the slot state changes from `ok` to `critical`
          or from `critical` to `ok`
      operationId: submitReading
      security:
        - bearerAuth: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ReadingRequest'
            examples:
              lobbySlot:
                summary: Reading for the A1 slot in the lobby machine
                value:
                  machine_id: automat-lobby
                  sensor_id: fach-a1
                  distance_mm: 184
                  measured_at: '2026-04-15T19:20:00Z'
      responses:
        '200':
          description: Reading processed successfully.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ReadingSuccessResponse'
              examples:
                ok:
                  value:
                    ok: true
                    machine_id: automat-lobby
                    sensor_id: fach-a1
                    slot_label: A1
                    units_estimated: 4
                    fill_percent: 63
                    state: ok
        '400':
          description: Invalid JSON body or malformed request payload.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                invalidJson:
                  value:
                    ok: false
                    error: Ungueltiger JSON-Body.
        '401':
          description: Missing or invalid Bearer token.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                unauthorized:
                  value:
                    ok: false
                    error: Nicht autorisiert.
        '404':
          description: The referenced machine or sensor is not configured.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                unknownMachineOrSensor:
                  value:
                    ok: false
                    error: Unbekannter Automat oder Sensor.
        '405':
          description: Only POST is supported for this endpoint.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                wrongMethod:
                  value:
                    ok: false
                    error: Nur POST ist erlaubt.
        '422':
          description: Semantic validation failed.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                missingIdentifiers:
                  value:
                    ok: false
                    error: machine_id und sensor_id sind erforderlich.
                nonNumericDistance:
                  value:
                    ok: false
                    error: distance_mm muss numerisch sein.
                invalidTimestamp:
                  value:
                    ok: false
                    error: measured_at ist kein gueltiger ISO-Zeitstempel.
        '500':
          description: Unexpected internal server error.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                internalError:
                  value:
                    ok: false
                    error: Interner Fehler.
    options:
      tags:
        - Readings
      summary: CORS preflight for readings
      description: |
        Preflight handler for browser-based clients. The endpoint responds with
        `204 No Content` and emits `Access-Control-Allow-Methods` and
        `Access-Control-Allow-Headers`.
      operationId: readingsPreflight
      responses:
        '204':
          description: Preflight accepted without a response body.
          headers:
            Access-Control-Allow-Methods:
              description: Allowed methods for this endpoint.
              schema:
                type: string
                example: POST, OPTIONS
            Access-Control-Allow-Headers:
              description: Allowed request headers for this endpoint.
              schema:
                type: string
                example: Authorization, Content-Type
  /api/v1/status.php:
    get:
      tags:
        - Status
      summary: Retrieve the current application status
      description: |
        Returns the aggregated state for the dashboard and admin panel.

        The response contains:
        - app metadata
        - machine and slot status
        - a summary section
        - the most recent alert log entries
      operationId: getStatus
      responses:
        '200':
          description: Aggregated status generated successfully.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/StatusResponse'
              examples:
                dashboard:
                  value:
                    ok: true
                    generated_at: '2026-04-15T20:10:00+00:00'
                    app:
                      name: Getraenkeautomat Monitor
                      dashboard_refresh_seconds: 15
                    summary:
                      machine_count: 2
                      slot_count: 3
                      critical_count: 1
                    machines:
                      - id: automat-lobby
                        name: Lobby Automat
                        location: Erdgeschoss
                        slots:
                          - machine_id: automat-lobby
                            machine_name: Lobby Automat
                            sensor_id: fach-a1
                            slot_label: A1
                            product_name: Cola 0,5l
                            fill_percent: 63
                            units_estimated: 4
                            max_units: 7
                            distance_mm: 184
                            state: ok
                            measured_at: '2026-04-15T19:20:00+00:00'
                            updated_at: '2026-04-15T19:20:02+00:00'
                            alert_below_units: 2
                            webhook_ids:
                              - lager-webhook
                            email_ids:
                              - lager-team
                    alerts:
                      - id: alert_680004979d8512.07480974
                        created_at: '2026-04-15T19:20:02+00:00'
                        payload:
                          event: critical
                          machine_id: automat-lobby
                          machine_name: Lobby Automat
                          sensor_id: fach-a1
                          slot_label: A1
                          product_name: Cola 0,5l
                          distance_mm: 320
                          units_estimated: 1
                          max_units: 7
                          fill_percent: 14
                          state: critical
                          previous_state: ok
                          measured_at: '2026-04-15T19:19:59+00:00'
                        deliveries:
                          webhooks:
                            - id: lager-webhook
                              success: false
                              message: Webhook nicht gefunden oder deaktiviert.
                          emails:
                            - id: lager-team
                              success: true
                              message: Email versendet.
        '405':
          description: Only GET is supported for this endpoint.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              examples:
                wrongMethod:
                  value:
                    ok: false
                    error: Nur GET ist erlaubt.
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: opaque token
      description: Bearer token stored in config.json under api.bearer_token.
  schemas:
    ReadingRequest:
      type: object
      additionalProperties: false
      required:
        - machine_id
        - sensor_id
        - distance_mm
      properties:
        machine_id:
          type: string
          description: Configured machine identifier from config.json.
          minLength: 1
          example: automat-lobby
        sensor_id:
          type: string
          description: Slot or sensor identifier within the machine.
          minLength: 1
          example: fach-a1
        distance_mm:
          type: number
          description: Measured distance in millimeters.
          example: 184
        measured_at:
          type:
            - string
            - 'null'
          description: |
            Optional measurement timestamp. When omitted or empty, the server uses
            the current time. Values are parsed with PHP `strtotime()` and returned
            as an ISO-8601 timestamp.
          format: date-time
          example: '2026-04-15T19:20:00Z'
    ReadingSuccessResponse:
      type: object
      additionalProperties: false
      required:
        - ok
        - machine_id
        - sensor_id
        - slot_label
        - units_estimated
        - fill_percent
        - state
      properties:
        ok:
          type: boolean
          const: true
        machine_id:
          type: string
          example: automat-lobby
        sensor_id:
          type: string
          example: fach-a1
        slot_label:
          type: string
          example: A1
        units_estimated:
          type: integer
          example: 4
        fill_percent:
          type: integer
          example: 63
        state:
          $ref: '#/components/schemas/SlotState'
    ErrorResponse:
      type: object
      additionalProperties: false
      required:
        - ok
        - error
      properties:
        ok:
          type: boolean
          const: false
        error:
          type: string
          example: Nicht autorisiert.
    StatusResponse:
      type: object
      additionalProperties: false
      required:
        - ok
        - generated_at
        - app
        - summary
        - machines
        - alerts
      properties:
        ok:
          type: boolean
          const: true
        generated_at:
          type: string
          format: date-time
          description: Timestamp when the response was generated.
        app:
          $ref: '#/components/schemas/AppStatus'
        summary:
          $ref: '#/components/schemas/StatusSummary'
        machines:
          type: array
          items:
            $ref: '#/components/schemas/MachineStatus'
        alerts:
          type: array
          items:
            $ref: '#/components/schemas/AlertEvent'
    AppStatus:
      type: object
      additionalProperties: false
      required:
        - name
        - dashboard_refresh_seconds
      properties:
        name:
          type: string
          example: Getraenkeautomat Monitor
        dashboard_refresh_seconds:
          type: integer
          minimum: 1
          example: 15
    StatusSummary:
      type: object
      additionalProperties: false
      required:
        - machine_count
        - slot_count
        - critical_count
      properties:
        machine_count:
          type: integer
          minimum: 0
          example: 2
        slot_count:
          type: integer
          minimum: 0
          example: 3
        critical_count:
          type: integer
          minimum: 0
          example: 1
    MachineStatus:
      type: object
      additionalProperties: false
      required:
        - id
        - name
        - location
        - slots
      properties:
        id:
          type: string
          example: automat-lobby
        name:
          type: string
          example: Lobby Automat
        location:
          type: string
          example: Erdgeschoss
        slots:
          type: array
          items:
            $ref: '#/components/schemas/SlotStatus'
    SlotStatus:
      type: object
      additionalProperties: false
      required:
        - machine_id
        - machine_name
        - sensor_id
        - slot_label
        - product_name
        - fill_percent
        - units_estimated
        - max_units
        - distance_mm
        - state
        - measured_at
        - updated_at
        - alert_below_units
        - webhook_ids
        - email_ids
      properties:
        machine_id:
          type: string
          example: automat-lobby
        machine_name:
          type: string
          example: Lobby Automat
        sensor_id:
          type: string
          example: fach-a1
        slot_label:
          type: string
          example: A1
        product_name:
          type: string
          example: Cola 0,5l
        fill_percent:
          type:
            - integer
            - 'null'
          minimum: 0
          maximum: 100
          description: Null until a first reading has been received.
          example: 63
        units_estimated:
          type:
            - integer
            - 'null'
          minimum: 0
          description: Null until a first reading has been received.
          example: 4
        max_units:
          type: integer
          minimum: 0
          example: 7
        distance_mm:
          type:
            - number
            - 'null'
          description: Last measured distance in millimeters.
          example: 184
        state:
          $ref: '#/components/schemas/SlotState'
        measured_at:
          type:
            - string
            - 'null'
          format: date-time
          example: '2026-04-15T19:20:00+00:00'
        updated_at:
          type:
            - string
            - 'null'
          format: date-time
          example: '2026-04-15T19:20:02+00:00'
        alert_below_units:
          type: integer
          minimum: 0
          example: 2
        webhook_ids:
          type: array
          items:
            type: string
          example:
            - lager-webhook
        email_ids:
          type: array
          items:
            type: string
          example:
            - lager-team
    SlotState:
      type: string
      enum:
        - ok
        - critical
        - unknown
      example: ok
    AlertEvent:
      type: object
      additionalProperties: false
      required:
        - id
        - created_at
        - payload
        - deliveries
      properties:
        id:
          type: string
          description: Unique alert log entry ID generated with PHP uniqid().
          example: alert_680004979d8512.07480974
        created_at:
          type: string
          format: date-time
          example: '2026-04-15T19:20:02+00:00'
        payload:
          $ref: '#/components/schemas/AlertPayload'
        deliveries:
          $ref: '#/components/schemas/AlertDeliveries'
    AlertPayload:
      type: object
      additionalProperties: false
      required:
        - event
        - machine_id
        - machine_name
        - sensor_id
        - slot_label
        - product_name
        - distance_mm
        - units_estimated
        - max_units
        - fill_percent
        - state
        - previous_state
        - measured_at
      properties:
        event:
          type: string
          enum:
            - critical
            - recovered
          example: critical
        machine_id:
          type: string
          example: automat-lobby
        machine_name:
          type: string
          example: Lobby Automat
        sensor_id:
          type: string
          example: fach-a1
        slot_label:
          type: string
          example: A1
        product_name:
          type: string
          example: Cola 0,5l
        distance_mm:
          type:
            - number
            - 'null'
          example: 320
        units_estimated:
          type:
            - integer
            - 'null'
          example: 1
        max_units:
          type:
            - integer
            - 'null'
          example: 7
        fill_percent:
          type:
            - integer
            - 'null'
          example: 14
        state:
          $ref: '#/components/schemas/SlotState'
        previous_state:
          type:
            - string
            - 'null'
          description: Previous slot state before the transition.
          example: ok
        measured_at:
          type:
            - string
            - 'null'
          format: date-time
          example: '2026-04-15T19:19:59+00:00'
    AlertDeliveries:
      type: object
      additionalProperties: false
      required:
        - webhooks
        - emails
      properties:
        webhooks:
          type: array
          items:
            $ref: '#/components/schemas/DeliveryResult'
        emails:
          type: array
          items:
            $ref: '#/components/schemas/DeliveryResult'
    DeliveryResult:
      type: object
      additionalProperties: false
      required:
        - id
        - success
        - message
      properties:
        id:
          type: string
          example: lager-team
        success:
          type: boolean
          example: true
        message:
          type: string
          example: Email versendet.