{
  "openapi": "3.1.2",
  "info": {
    "title": "Frankfurter API",
    "description": "Frankfurter is an open-source API for current and historical foreign exchange rates published by central banks.",
    "version": "2.0.0",
    "license": {
      "name": "MIT",
      "url": "https://github.com/lineofflight/frankfurter/blob/main/LICENSE"
    },
    "contact": {
      "url": "https://github.com/lineofflight/frankfurter/issues"
    }
  },
  "servers": [
    {
      "url": "https://api.frankfurter.dev/v2"
    }
  ],
  "paths": {
    "/rates": {
      "get": {
        "operationId": "getRates",
        "summary": "Get exchange rates",
        "description": "Returns exchange rates blended across providers. Without date params, returns the latest rates. Each record is a single currency pair.",
        "parameters": [
          { "$ref": "#/components/parameters/date" },
          { "$ref": "#/components/parameters/from" },
          { "$ref": "#/components/parameters/to" },
          { "$ref": "#/components/parameters/base" },
          { "$ref": "#/components/parameters/symbols" },
          { "$ref": "#/components/parameters/provider" }
        ],
        "responses": {
          "200": {
            "description": "Exchange rates",
            "content": {
              "application/json": {
                "schema": {
                  "type": "array",
                  "items": { "$ref": "#/components/schemas/Rate" }
                },
                "example": [
                  { "date": "2024-01-15", "base": "EUR", "quote": "USD", "rate": 1.089 },
                  { "date": "2024-01-15", "base": "EUR", "quote": "GBP", "rate": 0.8623 }
                ]
              }
            }
          },
          "400": { "$ref": "#/components/responses/BadRequest" },
          "404": { "$ref": "#/components/responses/NotFound" }
        }
      }
    },
    "/currencies": {
      "get": {
        "operationId": "getCurrencies",
        "summary": "Get available currencies",
        "description": "Returns available currencies with their names and which providers cover each.",
        "responses": {
          "200": {
            "description": "Available currencies",
            "content": {
              "application/json": {
                "schema": { "$ref": "#/components/schemas/Currencies" },
                "example": {
                  "EUR": { "name": "Euro", "providers": ["ECB"] },
                  "USD": { "name": "United States Dollar", "providers": ["ECB", "BOC"] },
                  "CAD": { "name": "Canadian Dollar", "providers": ["ECB", "BOC"] }
                }
              }
            }
          }
        }
      }
    },
    "/providers": {
      "get": {
        "operationId": "getProviders",
        "summary": "Get available data providers",
        "description": "Returns available exchange rate data providers with their base currency.",
        "responses": {
          "200": {
            "description": "Available providers",
            "content": {
              "application/json": {
                "schema": { "$ref": "#/components/schemas/Providers" },
                "example": {
                  "ECB": { "name": "European Central Bank", "base": "EUR" },
                  "BOC": { "name": "Bank of Canada", "base": "CAD" }
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "parameters": {
      "date": {
        "name": "date",
        "in": "query",
        "description": "Specific date (YYYY-MM-DD). Cannot be combined with from/to.",
        "required": false,
        "schema": {
          "type": "string",
          "format": "date",
          "example": "2024-01-15"
        }
      },
      "from": {
        "name": "from",
        "in": "query",
        "description": "Start of date range (YYYY-MM-DD)",
        "required": false,
        "schema": {
          "type": "string",
          "format": "date",
          "example": "2024-01-01"
        }
      },
      "to": {
        "name": "to",
        "in": "query",
        "description": "End of date range (YYYY-MM-DD). Defaults to today.",
        "required": false,
        "schema": {
          "type": "string",
          "format": "date",
          "example": "2024-01-31"
        }
      },
      "base": {
        "name": "base",
        "in": "query",
        "description": "Base currency (default: EUR)",
        "required": false,
        "schema": {
          "type": "string",
          "default": "EUR",
          "example": "USD"
        }
      },
      "symbols": {
        "name": "symbols",
        "in": "query",
        "description": "Comma-separated list of quote currencies to include",
        "required": false,
        "schema": {
          "type": "string",
          "example": "USD,GBP,JPY"
        }
      },
      "provider": {
        "name": "provider",
        "in": "query",
        "description": "Filter by data provider",
        "required": false,
        "schema": {
          "type": "string",
          "example": "ECB"
        }
      }
    },
    "schemas": {
      "Rate": {
        "type": "object",
        "properties": {
          "date": {
            "type": "string",
            "format": "date",
            "description": "The date of the rate"
          },
          "base": {
            "type": "string",
            "description": "Base currency code"
          },
          "quote": {
            "type": "string",
            "description": "Quote currency code"
          },
          "rate": {
            "type": "number",
            "description": "Exchange rate value",
            "exclusiveMinimum": 0
          }
        },
        "required": ["date", "base", "quote", "rate"]
      },
      "Currencies": {
        "type": "object",
        "additionalProperties": {
          "type": "object",
          "properties": {
            "name": {
              "type": "string",
              "description": "Full currency name"
            },
            "providers": {
              "type": "array",
              "items": { "type": "string" },
              "description": "Data providers that cover this currency"
            }
          },
          "required": ["name", "providers"]
        }
      },
      "Providers": {
        "type": "object",
        "additionalProperties": {
          "type": "object",
          "properties": {
            "name": {
              "type": "string",
              "description": "Full provider name"
            },
            "base": {
              "type": "string",
              "description": "Provider's native base currency"
            }
          },
          "required": ["name", "base"]
        }
      }
    },
    "responses": {
      "BadRequest": {
        "description": "Invalid request",
        "content": {
          "application/json": {
            "schema": {
              "type": "object",
              "properties": {
                "message": { "type": "string" }
              }
            }
          }
        }
      },
      "NotFound": {
        "description": "No data found",
        "content": {
          "application/json": {
            "schema": {
              "type": "object",
              "properties": {
                "message": { "type": "string" }
              }
            }
          }
        }
      }
    }
  }
}