{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://json-for-beginners.example/schemas/user-profile.json",
  "title": "User Profile Schema",
  "description": "A schema for validating user profile data",
  "type": "object",
  "required": ["id", "username", "email", "profile"],
  "properties": {
    "id": {
      "type": "string",
      "pattern": "^usr_[a-zA-Z0-9]{8}$",
      "description": "Unique user identifier starting with 'usr_' followed by 8 alphanumeric characters"
    },
    "username": {
      "type": "string",
      "minLength": 3,
      "maxLength": 30,
      "pattern": "^[a-zA-Z0-9_-]+$",
      "description": "Username between 3 and 30 characters, alphanumeric with underscores and hyphens"
    },
    "email": {
      "type": "string",
      "format": "email",
      "description": "Valid email address"
    },
    "profile": {
      "type": "object",
      "required": ["fullName", "age"],
      "properties": {
        "fullName": {
          "type": "string",
          "minLength": 2,
          "description": "User's full name"
        },
        "age": {
          "type": "integer",
          "minimum": 13,
          "maximum": 120,
          "description": "User's age in years"
        },
        "avatar": {
          "type": "string",
          "format": "uri",
          "description": "URL to user's avatar image"
        }
      }
    },
    "preferences": {
      "type": "object",
      "properties": {
        "theme": {
          "type": "string",
          "enum": ["light", "dark", "system"],
          "default": "system",
          "description": "User's preferred theme"
        },
        "notifications": {
          "type": "object",
          "properties": {
            "email": {
              "type": "boolean",
              "default": true
            },
            "push": {
              "type": "boolean",
              "default": false
            },
            "sms": {
              "type": "boolean",
              "default": false
            }
          }
        }
      }
    },
    "roles": {
      "type": "array",
      "items": {
        "type": "string",
        "enum": ["user", "admin", "moderator"]
      },
      "minItems": 1,
      "uniqueItems": true,
      "default": ["user"]
    },
    "metadata": {
      "type": "object",
      "properties": {
        "createdAt": {
          "type": "string",
          "format": "date-time"
        },
        "lastLogin": {
          "type": "string",
          "format": "date-time"
        },
        "version": {
          "type": "string",
          "pattern": "^\\d+\\.\\d+\\.\\d+$"
        }
      }
    }
  }
}