{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/relational-data-modeling/main/json-schema/relational-data-modeling-entity-schema.json",
  "title": "Relational Data Model Entity",
  "description": "An entity (table) definition in a relational data model, including its attributes, primary key, and relationships to other entities.",
  "type": "object",
  "required": ["name", "attributes"],
  "properties": {
    "name": {
      "type": "string",
      "description": "The name of the entity/table.",
      "minLength": 1
    },
    "description": {
      "type": "string",
      "description": "Description of the entity and its purpose."
    },
    "schema": {
      "type": "string",
      "description": "Database schema the entity belongs to."
    },
    "attributes": {
      "type": "array",
      "description": "List of attributes (columns) in the entity.",
      "items": {
        "$ref": "#/$defs/Attribute"
      },
      "minItems": 1
    },
    "primaryKey": {
      "type": "array",
      "description": "List of attribute names forming the primary key.",
      "items": {
        "type": "string"
      },
      "minItems": 1
    },
    "foreignKeys": {
      "type": "array",
      "description": "Foreign key relationships to other entities.",
      "items": {
        "$ref": "#/$defs/ForeignKey"
      }
    },
    "indexes": {
      "type": "array",
      "description": "Additional indexes on the entity.",
      "items": {
        "$ref": "#/$defs/Index"
      }
    },
    "normalForm": {
      "type": "string",
      "description": "The highest normal form this entity satisfies.",
      "enum": ["1NF", "2NF", "3NF", "BCNF", "4NF", "5NF"]
    }
  },
  "$defs": {
    "Attribute": {
      "type": "object",
      "required": ["name", "dataType"],
      "properties": {
        "name": {
          "type": "string",
          "description": "The attribute/column name."
        },
        "dataType": {
          "type": "string",
          "description": "SQL data type (e.g., VARCHAR, INTEGER, BOOLEAN, DATE)."
        },
        "nullable": {
          "type": "boolean",
          "description": "Whether the attribute can be NULL.",
          "default": true
        },
        "unique": {
          "type": "boolean",
          "description": "Whether the attribute must be unique.",
          "default": false
        },
        "default": {
          "description": "Default value for the attribute."
        },
        "description": {
          "type": "string",
          "description": "Description of the attribute."
        },
        "isPrimaryKey": {
          "type": "boolean",
          "description": "Whether this attribute is part of the primary key.",
          "default": false
        }
      }
    },
    "ForeignKey": {
      "type": "object",
      "required": ["columns", "referencedEntity", "referencedColumns"],
      "properties": {
        "name": {
          "type": "string",
          "description": "Name of the foreign key constraint."
        },
        "columns": {
          "type": "array",
          "items": { "type": "string" },
          "description": "Columns in this entity forming the foreign key."
        },
        "referencedEntity": {
          "type": "string",
          "description": "Name of the referenced entity."
        },
        "referencedColumns": {
          "type": "array",
          "items": { "type": "string" },
          "description": "Columns in the referenced entity."
        },
        "onDelete": {
          "type": "string",
          "enum": ["CASCADE", "SET NULL", "RESTRICT", "NO ACTION"],
          "description": "Action on delete."
        },
        "onUpdate": {
          "type": "string",
          "enum": ["CASCADE", "SET NULL", "RESTRICT", "NO ACTION"],
          "description": "Action on update."
        }
      }
    },
    "Index": {
      "type": "object",
      "required": ["name", "columns"],
      "properties": {
        "name": {
          "type": "string",
          "description": "Name of the index."
        },
        "columns": {
          "type": "array",
          "items": { "type": "string" },
          "description": "Columns included in the index."
        },
        "unique": {
          "type": "boolean",
          "description": "Whether the index enforces uniqueness.",
          "default": false
        },
        "type": {
          "type": "string",
          "enum": ["BTREE", "HASH", "GIN", "GIST", "BRIN"],
          "description": "Index implementation type."
        }
      }
    }
  }
}