{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://beyond-kle.org/schemas/elc-layer.json",
  "title": "ELC Layer - Electrical Wiring",
  "description": "Wiring between provider pins and key terminals",
  "type": "object",
  "required": ["version", "phyReference", "providers", "keys"],
  "properties": {
    "version": { "type": "string" },
    "phyReference": {
      "type": "object",
      "required": ["source", "checksum"],
      "properties": {
        "source": { "type": "string" },
        "checksum": { "type": "string" }
      }
    },
    "providers": {
      "type": "array",
      "items": { "$ref": "#/$defs/provider" }
    },
    "keys": {
      "type": "array",
      "items": { "$ref": "#/$defs/keyWiring" }
    },
    "ledChains": {
      "type": "array",
      "items": { "$ref": "#/$defs/ledChain" }
    }
  },
  "$defs": {
    "pinRef": {
      "type": "string",
      "pattern": "^(VCC|GND|[^.]+\\.[^.]+)$",
      "description": "\"<provider id>.<pin name>\", or the reserved power rails VCC / GND"
    },
    "provider": {
      "oneOf": [{ "$ref": "#/$defs/mcuProvider" }, { "$ref": "#/$defs/analogMuxProvider" }]
    },
    "mcuProvider": {
      "type": "object",
      "required": ["id", "kind", "part"],
      "properties": {
        "id": { "type": "string" },
        "kind": { "const": "mcu" },
        "part": {
          "type": "string",
          "description": "Part number. Used to interpret pin names"
        }
      }
    },
    "analogMuxProvider": {
      "type": "object",
      "required": ["id", "kind", "channels", "select", "common"],
      "properties": {
        "id": { "type": "string" },
        "kind": { "const": "analog-mux" },
        "channels": {
          "type": "integer",
          "minimum": 1,
          "description": "Number of logical pins provided. Pin names are \"0\"..\"channels-1\""
        },
        "select": {
          "type": "array",
          "items": { "$ref": "#/$defs/pinRef" },
          "description": "Select pins, least significant bit first"
        },
        "common": { "$ref": "#/$defs/pinRef" },
        "enable": { "$ref": "#/$defs/pinRef" }
      }
    },
    "keyWiring": {
      "oneOf": [{ "$ref": "#/$defs/contactKey" }, { "$ref": "#/$defs/analogKey" }]
    },
    "contactKey": {
      "type": "object",
      "required": ["key", "detect", "terminals"],
      "properties": {
        "key": {
          "type": "string",
          "description": "Reference to PHY layer key ID"
        },
        "detect": { "const": "contact" },
        "terminals": {
          "type": "object",
          "description": "Non-polar. a and b carry no ordering meaning",
          "required": ["a", "b"],
          "properties": {
            "a": { "$ref": "#/$defs/pinRef" },
            "b": { "$ref": "#/$defs/pinRef" }
          }
        },
        "diode": {
          "type": "string",
          "enum": ["a-to-b", "b-to-a"],
          "description": "Anode side comes first. Omitted means no diode"
        }
      }
    },
    "analogKey": {
      "type": "object",
      "required": ["key", "detect", "terminals"],
      "properties": {
        "key": {
          "type": "string",
          "description": "Reference to PHY layer key ID"
        },
        "detect": { "const": "analog" },
        "terminals": {
          "type": "object",
          "required": ["out", "vcc", "gnd"],
          "properties": {
            "out": { "$ref": "#/$defs/pinRef" },
            "vcc": { "$ref": "#/$defs/pinRef" },
            "gnd": { "$ref": "#/$defs/pinRef" }
          }
        }
      }
    },
    "ledChain": {
      "type": "object",
      "required": ["id", "data", "order"],
      "properties": {
        "id": { "type": "string" },
        "data": { "$ref": "#/$defs/pinRef" },
        "order": {
          "type": "array",
          "items": { "type": "string" },
          "description": "PHY node IDs. The position in the array is the LED number"
        }
      }
    }
  }
}