{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://abdess.github.io/retrobios/api/v1/schemas/game-headers.schema.json",
  "title": "RetroBIOS game header readers",
  "description": "Where a game file states what a core reads from it, and how each core's code turns those bytes into a region, a video standard or a label (games/headers.yml). Every rule cites the emulator source at the pin its profile records.",
  "type": "object",
  "additionalProperties": false,
  "required": [
    "version",
    "containers",
    "systems"
  ],
  "$defs": {
    "ref": {
      "type": "string",
      "description": "owner/repo@<sha, 8+ hex> path:line[-line], further places joined by ', '.",
      "pattern": "^[\\w.-]+/[\\w.-]+@[0-9a-f]{8,40} \\S"
    },
    "region_list": {
      "type": "array",
      "minItems": 1,
      "items": {
        "type": "string",
        "pattern": "^[a-z][a-z-]*$"
      },
      "uniqueItems": true
    },
    "outcome": {
      "type": "object",
      "additionalProperties": false,
      "minProperties": 1,
      "properties": {
        "regions": {
          "$ref": "#/$defs/region_list"
        },
        "standard": {
          "enum": [
            "ntsc",
            "pal"
          ]
        },
        "label": {
          "type": "string",
          "minLength": 1
        }
      }
    },
    "fallback": {
      "description": "What a decoder or a core answers when nothing matches: a region list, an outcome, or 'unknown' (the installer keeps every region).",
      "oneOf": [
        {
          "const": "unknown"
        },
        {
          "$ref": "#/$defs/region_list"
        },
        {
          "$ref": "#/$defs/outcome"
        }
      ]
    },
    "value": {
      "type": "object",
      "required": [
        "value"
      ],
      "additionalProperties": false,
      "properties": {
        "value": {
          "type": [
            "string",
            "integer"
          ]
        },
        "regions": {
          "$ref": "#/$defs/region_list"
        },
        "standard": {
          "enum": [
            "ntsc",
            "pal"
          ]
        },
        "label": {
          "type": "string",
          "minLength": 1
        }
      },
      "anyOf": [
        {
          "required": [
            "regions"
          ]
        },
        {
          "required": [
            "standard"
          ]
        },
        {
          "required": [
            "label"
          ]
        }
      ]
    },
    "decode": {
      "type": "object",
      "required": [
        "kind"
      ],
      "properties": {
        "kind": {
          "enum": [
            "exact-prefix",
            "contains-normalized",
            "prefix-nocase",
            "char-at",
            "letters",
            "integer",
            "bit",
            "country-bits",
            "serial",
            "predicate"
          ]
        },
        "values": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/value"
          }
        },
        "otherwise": {
          "$ref": "#/$defs/fallback"
        },
        "missing": {
          "$ref": "#/$defs/fallback"
        },
        "normalize": {
          "type": "string"
        },
        "requires": {
          "type": "string"
        },
        "index": {
          "type": "integer",
          "minimum": 0
        },
        "guard": {
          "type": "string"
        },
        "words": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/value"
          }
        },
        "letters": {
          "type": "object",
          "additionalProperties": {
            "type": "integer"
          }
        },
        "hex_digits": {
          "type": "boolean"
        },
        "priority": {
          "type": "array",
          "items": {
            "type": "object",
            "additionalProperties": false,
            "required": [
              "bit",
              "regions"
            ],
            "properties": {
              "bit": {
                "type": "integer"
              },
              "regions": {
                "$ref": "#/$defs/region_list"
              }
            }
          }
        },
        "all": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/condition"
          },
          "minItems": 1
        },
        "then": {
          "$ref": "#/$defs/outcome"
        }
      },
      "allOf": [
        {
          "if": {
            "properties": {
              "kind": {
                "const": "serial"
              }
            }
          },
          "then": {
            "properties": {
              "kind": true
            },
            "additionalProperties": false
          }
        },
        {
          "if": {
            "properties": {
              "kind": {
                "const": "predicate"
              }
            }
          },
          "then": {
            "required": [
              "all",
              "then",
              "otherwise"
            ]
          }
        },
        {
          "if": {
            "properties": {
              "kind": {
                "enum": [
                  "serial",
                  "predicate"
                ]
              }
            }
          },
          "else": {
            "required": [
              "otherwise"
            ],
            "anyOf": [
              {
                "required": [
                  "values"
                ]
              },
              {
                "required": [
                  "words",
                  "priority"
                ]
              }
            ]
          }
        }
      ]
    },
    "reader": {
      "type": "object",
      "additionalProperties": false,
      "required": [
        "description",
        "applies_to",
        "location",
        "decode",
        "source_ref",
        "re_read"
      ],
      "properties": {
        "description": {
          "type": "string",
          "minLength": 1
        },
        "applies_to": {
          "type": "object",
          "additionalProperties": false,
          "required": [
            "media",
            "extensions"
          ],
          "properties": {
            "media": {
              "oneOf": [
                {
                  "type": "string"
                },
                {
                  "type": "array",
                  "items": {
                    "type": "string"
                  },
                  "minItems": 1
                }
              ]
            },
            "extensions": {
              "type": "array",
              "minItems": 1,
              "items": {
                "type": "string",
                "pattern": "^\\.[a-z0-9]+$"
              },
              "uniqueItems": true
            }
          }
        },
        "magic": {
          "type": "object",
          "minProperties": 1
        },
        "location": {
          "type": "object",
          "minProperties": 1
        },
        "fields": {
          "type": "object"
        },
        "decode": {
          "$ref": "#/$defs/decode"
        },
        "note": {
          "type": "string"
        },
        "source_ref": {
          "$ref": "#/$defs/ref"
        },
        "re_read": {
          "type": "boolean"
        }
      }
    },
    "core": {
      "type": "object",
      "additionalProperties": false,
      "required": [
        "order",
        "source_ref",
        "re_read"
      ],
      "properties": {
        "order": {
          "type": "array",
          "description": "Reader ids of the same system, in the order the core's code consults them.",
          "items": {
            "type": "string"
          }
        },
        "otherwise": {
          "$ref": "#/$defs/fallback"
        },
        "selects_bios": {
          "type": "boolean",
          "description": "False when nothing the readers return changes which BIOS file the core opens."
        },
        "preference": {
          "oneOf": [
            {
              "type": "string"
            },
            {
              "type": "array",
              "items": {
                "type": "string"
              }
            }
          ]
        },
        "default_preference": {
          "type": "array",
          "items": {
            "type": "string"
          }
        },
        "overridden_by": {
          "type": "string"
        },
        "first_disc_only": {
          "type": "boolean"
        },
        "note": {
          "type": "string"
        },
        "source_ref": {
          "$ref": "#/$defs/ref"
        },
        "re_read": {
          "type": "boolean"
        }
      }
    },
    "condition": {
      "description": "One test on the file. Byte tests read at offset (relative to the reader location's place when it lists candidates), or through the u32 at pointer. all and any nest tests.",
      "type": "object",
      "minProperties": 1,
      "additionalProperties": false,
      "properties": {
        "offset": {
          "type": "integer",
          "minimum": 0
        },
        "pointer": {
          "type": "integer",
          "minimum": 0
        },
        "length": {
          "type": "integer",
          "minimum": 1
        },
        "encoding": {
          "enum": [
            "u8",
            "u32le",
            "u32be"
          ]
        },
        "mask": {
          "type": "integer"
        },
        "equals": {
          "type": "integer"
        },
        "not_equals": {
          "type": "integer"
        },
        "in": {
          "type": "array",
          "items": {
            "type": "integer"
          },
          "minItems": 1
        },
        "min": {
          "type": "integer"
        },
        "text": {
          "type": "string"
        },
        "not_text": {
          "type": "string"
        },
        "file_size": {
          "type": "object",
          "additionalProperties": false,
          "properties": {
            "min": {
              "type": "integer"
            },
            "max": {
              "type": "integer"
            }
          }
        },
        "data_after_header": {
          "type": "object",
          "additionalProperties": {
            "type": "integer"
          }
        },
        "zero_run": {
          "type": "integer",
          "minimum": 1
        },
        "all": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/condition"
          },
          "minItems": 1
        },
        "any": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/condition"
          },
          "minItems": 1
        }
      }
    }
  },
  "properties": {
    "version": {
      "const": 1
    },
    "containers": {
      "type": "object",
      "additionalProperties": {
        "type": "object",
        "required": [
          "description",
          "source_ref",
          "re_read"
        ],
        "properties": {
          "description": {
            "type": "string"
          },
          "source_ref": {
            "$ref": "#/$defs/ref"
          },
          "re_read": {
            "type": "boolean"
          }
        }
      }
    },
    "systems": {
      "type": "object",
      "propertyNames": {
        "pattern": "^[a-z0-9][a-z0-9-]*$"
      },
      "additionalProperties": {
        "type": "object",
        "additionalProperties": false,
        "required": [
          "readers",
          "cores"
        ],
        "properties": {
          "readers": {
            "type": "object",
            "propertyNames": {
              "pattern": "^[a-z0-9][a-z0-9-]*$"
            },
            "additionalProperties": {
              "$ref": "#/$defs/reader"
            }
          },
          "cores": {
            "type": "object",
            "propertyNames": {
              "pattern": "^[a-z0-9][a-z0-9_-]*$"
            },
            "additionalProperties": {
              "$ref": "#/$defs/core"
            }
          }
        }
      }
    }
  }
}