{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://drillflow.de/schema/drillflow-document.schema.json",
  "title": "DrillFlow document",
  "description": "A DrillFlow diagram document. Diagrams live in a flat map; hierarchy is expressed by node.childDiagramId / diagram.parentNodeId references, never by nesting the JSON. Prose reference: https://drillflow.de/en/format/",
  "type": "object",
  "required": ["id", "title", "rootDiagramId", "diagrams", "createdAt", "updatedAt"],
  "properties": {
    "id": { "type": "string", "minLength": 1 },
    "title": { "type": "string" },
    "rootDiagramId": {
      "type": "string",
      "minLength": 1,
      "description": "Key into `diagrams`. Every document has exactly one root diagram."
    },
    "diagrams": {
      "type": "object",
      "description": "Map of diagram id to diagram. Must contain the key named by rootDiagramId.",
      "minProperties": 1,
      "maxProperties": 5000,
      "additionalProperties": { "$ref": "#/$defs/diagram" }
    },
    "createdAt": { "$ref": "#/$defs/timestamp" },
    "updatedAt": { "$ref": "#/$defs/timestamp" }
  },
  "$defs": {
    "timestamp": {
      "type": "integer",
      "minimum": 0,
      "description": "Unix epoch MILLISECONDS (not seconds)."
    },
    "color": {
      "type": "string",
      "description": "Any CSS colour. `url(...)` is refused: a colour lands in a `background` shorthand, so it is a way to make a shared document fetch a remote resource and report the viewer's IP back.",
      "not": { "pattern": "url\\s*\\(" }
    },
    "typography": {
      "type": "object",
      "properties": {
        "fontSize": { "type": "number", "exclusiveMinimum": 0, "description": "px, default 14" },
        "fontFamily": { "enum": ["sketch", "sans", "serif", "mono"], "description": "default 'sketch'" },
        "bold": { "type": "boolean" },
        "italic": { "type": "boolean" },
        "align": { "enum": ["left", "center", "right"], "description": "default 'center'" }
      }
    },
    "point": {
      "type": "object",
      "required": ["x", "y"],
      "properties": {
        "x": { "type": "number" },
        "y": { "type": "number" }
      }
    },
    "inkPoint": {
      "type": "object",
      "required": ["x", "y"],
      "properties": {
        "x": { "type": "number" },
        "y": { "type": "number" },
        "p": { "type": "number", "description": "Stylus pressure; present only when real pressure was reported." }
      }
    },
    "layer": {
      "type": "object",
      "required": ["id", "name", "visible"],
      "properties": {
        "id": { "type": "string", "minLength": 1 },
        "name": { "type": "string" },
        "visible": { "type": "boolean" }
      }
    },
    "node": {
      "type": "object",
      "required": ["id", "type", "label", "x", "y"],
      "allOf": [
        { "$ref": "#/$defs/typography" },
        {
          "if": { "properties": { "type": { "const": "draw" } }, "required": ["type"] },
          "then": {
            "required": ["points"],
            "properties": { "points": { "minItems": 1 } }
          }
        },
        {
          "if": { "properties": { "type": { "const": "image" } }, "required": ["type"] },
          "then": { "required": ["src"] }
        },
        {
          "if": {
            "properties": { "type": { "enum": ["text", "pin"] } },
            "required": ["type"]
          },
          "then": {
            "not": { "required": ["childDiagramId"] },
            "description": "text and pin nodes cannot own a subflow."
          }
        }
      ],
      "properties": {
        "id": {
          "type": "string",
          "minLength": 1,
          "description": "Unique within its own diagram (not globally)."
        },
        "type": {
          "enum": ["rect", "circle", "diamond", "text", "pin", "draw", "image"]
        },
        "label": { "type": "string", "description": "May be empty. \\n is a line break." },
        "x": { "type": "number", "description": "Top-left corner, flow units. Y grows downward." },
        "y": { "type": "number" },
        "w": { "type": "number", "exclusiveMinimum": 0, "description": "Omitted = per-type default (rect 140x60, circle/diamond 100x100, text 140x40, pin 12x12, draw 40x40, image 200x150)." },
        "h": { "type": "number", "exclusiveMinimum": 0 },
        "childDiagramId": {
          "type": "string",
          "minLength": 1,
          "description": "Key into the document's `diagrams`. That diagram must carry `parentNodeId` pointing back at this node."
        },
        "color": { "$ref": "#/$defs/color" },
        "colorMode": { "enum": ["fill", "stroke"], "description": "default 'fill'" },
        "lineStyle": {
          "enum": ["solid", "dashed", "dotted", "double", "none"],
          "description": "Shape outline; default 'solid'."
        },
        "rotation": {
          "type": "number",
          "minimum": 0,
          "exclusiveMaximum": 360,
          "description": "Degrees clockwise. Shape, text and image nodes only."
        },
        "notes": { "type": "string" },
        "layerId": { "type": "string", "minLength": 1, "description": "Must name a layer of the SAME diagram. Absent = implicit base sheet." },
        "points": {
          "type": "array",
          "items": { "$ref": "#/$defs/inkPoint" },
          "description": "draw nodes only: ink points RELATIVE to the node's x/y."
        },
        "strokeWidth": { "enum": ["s", "m", "l"], "description": "draw nodes only; default 'm'" },
        "src": {
          "type": "string",
          "pattern": "^data:image/",
          "description": "image nodes only: inline data URI. Remote URLs are refused — they would report every viewer's IP back to whoever published the document."
        },
        "lockAspect": { "type": "boolean", "description": "image nodes only; absent = true" }
      }
    },
    "edgeEndpoint": {
      "type": "object",
      "required": ["nodeId"],
      "properties": {
        "nodeId": {
          "type": "string",
          "minLength": 1,
          "description": "A node in the SAME diagram as the edge. Edges never cross diagrams."
        },
        "anchorDeg": {
          "type": "number",
          "description": "Pins the endpoint to a fixed outline point: degrees clockwise from +X in the node's UNROTATED frame (0 right, 90 bottom, 180 left, 270 top). Omit for a floating endpoint, which is recomputed toward the other end — that is the recommended default."
        },
        "handleId": {
          "deprecated": true,
          "type": "string",
          "description": "Retired four-handle model. Still parsed from old documents, never rendered from. Do not write it."
        }
      }
    },
    "edge": {
      "type": "object",
      "required": ["id", "from", "to"],
      "allOf": [{ "$ref": "#/$defs/typography" }],
      "properties": {
        "id": { "type": "string", "minLength": 1 },
        "from": { "$ref": "#/$defs/edgeEndpoint" },
        "to": { "$ref": "#/$defs/edgeEndpoint" },
        "label": { "type": "string" },
        "arrowType": {
          "enum": ["directed", "bidirectional", "undirected"],
          "description": "default 'directed'"
        },
        "edgeStyle": {
          "enum": ["straight", "bezier"],
          "description": "Per-edge override; absent follows the viewer's preference."
        },
        "lineStyle": {
          "enum": ["solid", "dashed", "dotted"],
          "description": "default 'solid'. Narrower than a node's lineStyle — no 'double'/'none'."
        },
        "color": { "$ref": "#/$defs/color" },
        "arrowSize": { "type": "number", "exclusiveMinimum": 0, "description": "px, default 20" },
        "waypoints": { "type": "array", "items": { "$ref": "#/$defs/point" } },
        "layerId": {
          "type": "string",
          "minLength": 1,
          "description": "Must not be an EARLIER sheet than either endpoint's layer."
        }
      }
    },
    "diagram": {
      "type": "object",
      "required": ["id", "title", "nodes", "edges"],
      "properties": {
        "id": { "type": "string", "minLength": 1, "description": "Should equal this diagram's key in the `diagrams` map." },
        "title": { "type": "string", "description": "A subflow's title mirrors its owning node's label." },
        "parentNodeId": {
          "type": "string",
          "minLength": 1,
          "description": "Present exactly on sub-diagrams: the id of the node that owns this diagram."
        },
        "nodes": { "type": "array", "maxItems": 20000, "items": { "$ref": "#/$defs/node" } },
        "edges": { "type": "array", "maxItems": 20000, "items": { "$ref": "#/$defs/edge" } },
        "layers": {
          "type": "array",
          "items": { "$ref": "#/$defs/layer" },
          "description": "Ordered transparency sheets, base-first, over an implicit base sheet (index -1). Absent = everything on the base."
        }
      }
    }
  }
}