{
  "$schema": "http://json-schema.org/draft/2020-12/schema",
  "$id": "https://open-forum.onestonesoup.org/HomeLab/DBModelView/database-model-schema.json",
  "title": "Database Model",
  "description": "JSON Schema for relational database models",
  "type": "object",
  "properties": {
    "tables": {
      "type": "array",
      "description": "Collection of database tables",
      "items": { "$ref": "#/$defs/table" }
    },
    "relationships": {
      "type": "array",
      "description": "Explicit relationships between tables",
      "items": { "$ref": "#/$defs/relationship" }
    }
  },
  "required": ["tables"],

  "$defs": {
    "table": {
      "type": "object",
      "description": "A database table with columns, indexes, and constraints",
      "properties": {
        "id": {
          "type": "string",
          "description": "Unique identifier for the table (defaults to name if omitted)"
        },
        "name": {
          "type": "string",
          "description": "Table name as it appears in the database"
        },
        "columns": {
          "type": "array",
          "description": "Column definitions",
          "items": { "$ref": "#/$defs/column" }
        },
        "indexes": {
          "type": "array",
          "description": "Index definitions",
          "items": { "$ref": "#/$defs/index" }
        },
        "constraints": {
          "type": "array",
          "description": "Multi-column constraints (unique, check, exclusion)",
          "items": { "$ref": "#/$defs/constraint" }
        },
        "primaryKey": {
          "type": "object",
          "description": "Composite primary key definition",
          "properties": {
            "columns": {
              "type": "array",
              "items": { "type": "string" },
              "description": "Column names that form the composite primary key"
            }
          },
          "required": ["columns"]
        },
        "extensions": {
          "type": "object",
          "description": "Optional tool-specific metadata, e.g. description, notes, datasource, graphical layout, color"
        }
      },
      "required": ["name", "columns"]
    },

    "column": {
      "type": "object",
      "description": "A table column with its data type and constraints",
      "properties": {
        "name": {
          "type": "string",
          "description": "Column name"
        },
        "type": {
          "type": "string",
          "description": "Data type (e.g., uuid, text, integer, timestamptz, boolean)"
        },
        "primaryKey": {
          "type": "boolean",
          "description": "Whether this column is a primary key"
        },
        "unique": {
          "type": "boolean",
          "description": "Whether values must be unique"
        },
        "nullable": {
          "type": "boolean",
          "description": "Whether NULL values are allowed (default: true)"
        },
        "required": {
          "type": "boolean",
          "description": "Alias for nullable=false"
        },
        "notNull": {
          "type": "boolean",
          "description": "Alias for nullable=false"
        },
        "default": {
          "description": "Default value expression (can be string, number, boolean, or null)"
        },
        "foreignKey": {
          "oneOf": [
            { "type": "string", "description": "Simple reference as 'table.column'" },
            { "$ref": "#/$defs/foreignKey" }
          ]
        },
        "description": {
          "type": "string",
          "description": "Human-readable description of the column"
        },
        "generated": {
          "enum": ["ALWAYS", "BY DEFAULT"],
          "description": "Generated column specification"
        }
      },
      "required": ["name", "type"]
    },

    "foreignKey": {
      "type": "object",
      "description": "Foreign key reference to another table",
      "properties": {
        "targetTable": {
          "type": "string",
          "description": "Referenced table name or id"
        },
        "targetColumn": {
          "type": "string",
          "description": "Referenced column name"
        },
        "table": {
          "type": "string",
          "description": "Alias for targetTable"
        },
        "column": {
          "type": "string",
          "description": "Alias for targetColumn"
        },
        "onDelete": {
          "enum": ["CASCADE", "SET NULL", "SET DEFAULT", "RESTRICT", "NO ACTION"],
          "description": "Action on delete"
        },
        "onUpdate": {
          "enum": ["CASCADE", "SET NULL", "SET DEFAULT", "RESTRICT", "NO ACTION"],
          "description": "Action on update"
        },
        "name": {
          "type": "string",
          "description": "Foreign key constraint name"
        }
      }
    },

    "index": {
      "type": "object",
      "description": "Database index for performance optimization",
      "properties": {
        "name": {
          "type": "string",
          "description": "Index name"
        },
        "columns": {
          "type": "array",
          "items": { "type": "string" },
          "description": "Column names included in the index"
        },
        "expression": {
          "type": "string",
          "description": "Expression for functional/computed indexes (e.g., 'lower(email)')"
        },
        "unique": {
          "type": "boolean",
          "description": "Whether the index enforces uniqueness"
        },
        "method": {
          "type": "string",
          "description": "Index method (e.g., btree, hash, gin, gist, brin)"
        },
        "where": {
          "type": "string",
          "description": "Partial index filter condition"
        }
      },
      "required": ["name"]
    },

    "constraint": {
      "type": "object",
      "description": "Multi-column constraint",
      "properties": {
        "name": {
          "type": "string",
          "description": "Constraint name"
        },
        "type": {
          "enum": ["unique", "check", "exclusion"],
          "description": "Constraint type"
        },
        "columns": {
          "type": "array",
          "items": { "type": "string" },
          "description": "Column names involved in the constraint",
          "minItems": 1
        },
        "expression": {
          "type": "string",
          "description": "Check constraint expression (for type='check')"
        }
      },
      "required": ["name", "type", "columns"]
    },

    "relationship": {
      "type": "object",
      "description": "Relationship between tables",
      "properties": {
        "type": {
          "enum": ["foreignKey", "replication", "materializes", "view", "inheritance"],
          "description": "Type of relationship"
        },
        "sourceTable": {
          "type": "string",
          "description": "Source table id or name"
        },
        "targetTable": {
          "type": "string",
          "description": "Target table id or name"
        },
        "sourceColumn": {
          "type": "string",
          "description": "Source column name (for foreign keys)"
        },
        "targetColumn": {
          "type": "string",
          "description": "Target column name (for foreign keys)"
        },
        "fkName": {
          "type": "string",
          "description": "Foreign key constraint name"
        },
        "kind": {
          "type": "string",
          "description": "Alias for type"
        }
      },
      "required": ["type", "sourceTable", "targetTable"]
    }
  }
}