{
  "openapi": "3.0.0",
  "info": {
    "title": "CTA LineWatch",
    "description": "Unofficial Chicago CTA 'L' arrivals and lines API (CodeIgniter 4)",
    "version": "1.0.0",
    "contact": {
      "name": "CTA LineWatch",
      "url": "https://github.com/zkm/cta-linewatch"
    }
  },
  "servers": [
    {
      "url": "https://your-domain.com",
      "description": "Production server"
    },
    {
      "url": "http://localhost:8080",
      "description": "Development server"
    }
  ],
  "paths": {
    "/arrivals": {
      "get": {
        "summary": "Get train arrival information",
        "description": "Returns arrival information for CTA trains at specified stations",
        "parameters": [
          {
            "name": "station_id",
            "in": "query",
            "description": "Station identifier",
            "schema": {
              "type": "string"
            }
          },
          {
            "name": "line",
            "in": "query",
            "description": "Train line filter (optional)",
            "schema": {
              "type": "string",
              "enum": ["red", "blue", "green", "brown", "orange", "purple", "pink", "yellow"]
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Successful response",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "status": {
                      "type": "string",
                      "example": "success"
                    },
                    "data": {
                      "type": "object"
                    },
                    "timestamp": {
                      "type": "string",
                      "format": "date-time"
                    }
                  }
                }
              }
            }
          }
        }
      }
    },
    "/lines": {
      "get": {
        "summary": "Get available train lines",
        "description": "Returns information about all available CTA train lines",
        "responses": {
          "200": {
            "description": "List of train lines",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "status": {
                      "type": "string",
                      "example": "success"
                    },
                    "data": {
                      "type": "array",
                      "items": {
                        "type": "object",
                        "properties": {
                          "line": {
                            "type": "string"
                          },
                          "color": {
                            "type": "string"
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    },
    "/lines/{line}": {
      "get": {
        "summary": "Get stations for a specific line",
        "description": "Returns all stations for a specific train line",
        "parameters": [
          {
            "name": "line",
            "in": "path",
            "required": true,
            "description": "Train line name",
            "schema": {
              "type": "string",
              "enum": ["red", "blue", "green", "brown", "orange", "purple", "pink", "yellow"]
            }
          }
        ],
        "responses": {
          "200": {
            "description": "List of stations for the line",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "status": {
                      "type": "string",
                      "example": "success"
                    },
                    "data": {
                      "type": "array",
                      "items": {
                        "type": "object",
                        "properties": {
                          "station_id": {
                            "type": "string"
                          },
                          "station_name": {
                            "type": "string"
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "Error": {
        "type": "object",
        "properties": {
          "status": {
            "type": "string",
            "example": "error"
          },
          "message": {
            "type": "string"
          },
          "code": {
            "type": "integer"
          }
        }
      }
    }
  }
}