// Type definitions for joi v9.0.0
// Project: https://github.com/hapijs/joi
// Definitions by: Bart van der Schoor <https://github.com/Bartvds>, Laurence Dougal Myers <https://github.com/laurence-myers>, Christopher Glantschnig <https://github.com/cglantschnig>, David Broder-Rodgers <https://github.com/DavidBR-SW>, Gael Magnan de Bornier <hhttps://github.com/GaelMagnan>
// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped

// TODO express type of Schema in a type-parameter (.default, .valid, .example etc)

declare module 'joi' {

	export interface ValidationOptions {
		/**
		 * when true, stops validation on the first error, otherwise returns all the errors found. Defaults to true.
		 */
		abortEarly?: boolean;
		/**
		 * when true, attempts to cast values to the required types (e.g. a string to a number). Defaults to true.
		 */
		convert?: boolean;
		/**
		 * when true, allows object to contain unknown keys which are ignored. Defaults to false.
		 */
		allowUnknown?: boolean;
		/**
		 * when true, ignores unknown keys with a function value. Defaults to false.
		 */
		skipFunctions?: boolean;
		/**
		 * when true, unknown keys are deleted (only when value is an object). Defaults to false.
		 */
		stripUnknown?: boolean;
		/**
		 * overrides individual error messages. Defaults to no override ({}).
		 */
		language?: Object;
		/**
		 * sets the default presence requirements. Supported modes: 'optional', 'required', and 'forbidden'. Defaults to 'optional'.
		 */
		presence?: string;
		/**
		 * provides an external data set to be used in references
		 */
		context?: Object;
	}

	export interface RenameOptions {
		/**
		 * if true, does not delete the old key name, keeping both the new and old keys in place. Defaults to false.
		 */
		alias?: boolean;
		/**
		 * if true, allows renaming multiple keys to the same destination where the last rename wins. Defaults to false.
		 */
		multiple?: boolean;
		/**
		 * if true, allows renaming a key over an existing key. Defaults to false.
		 */
		override?: boolean;
		/**
		 * if true, skip renaming of a key if it's undefined. Defaults to false.
		 */
		ignoreUndefined?: boolean;
	}

	export interface EmailOptions {
		/**
		 * Numerical threshold at which an email address is considered invalid
		 */
		errorLevel?: number | boolean;
		/**
		 * Specifies a list of acceptable TLDs.
		 */
		tldWhitelist?: string[] | Object;
		/**
		 * Number of atoms required for the domain. Be careful since some domains, such as io, directly allow email.
		 */
		minDomainAtoms?: number;
	}

	export interface IpOptions {
		/**
		 * One or more IP address versions to validate against. Valid values: ipv4, ipv6, ipvfuture
		 */
		version ?: string | string[];
		/**
		 * Used to determine if a CIDR is allowed or not. Valid values: optional, required, forbidden
		 */
		cidr?: string;
	}

	export interface UriOptions {
		/**
		 * Specifies one or more acceptable Schemes, should only include the scheme name.
		 * Can be an Array or String (strings are automatically escaped for use in a Regular Expression).
		 */
		scheme ?: string | RegExp | Array<string | RegExp>;
	}

	export interface WhenOptions<T> {
		/**
		 * the required condition joi type.
		 */
		is: T;
		/**
		 * the alternative schema type if the condition is true. Required if otherwise is missing.
		 */
		then?: Schema;
		/**
		 * the alternative schema type if the condition is false. Required if then is missing
		 */
		otherwise?: Schema;
	}

	export interface ReferenceOptions {
		separator?: string;
		contextPrefix?: string;
	}

	export interface IPOptions {
		version?: Array<string>;
		cidr?: string
	}

	export interface ValidationError extends Error {
		message: string;
		details: ValidationErrorItem[];
		simple(): string;
		annotated(): string;
	}

	export interface ValidationErrorItem {
		message: string;
		type: string;
		path: string;
		options?: ValidationOptions;
	}

	export interface ValidationResult<T> {
		error: ValidationError;
		value: T;
	}

	export interface SchemaMap {
		[key: string]: Schema;
	}

	export interface Schema extends AnySchema<Schema> {

	}

	export interface Reference extends Schema {

	}

	export interface AnySchema<T extends AnySchema<Schema>> {
		/**
		 * Whitelists a value
		 */
		allow(value: any, ...values: any[]): T;
		allow(values: any[]): T;

		/**
		 * Adds the provided values into the allowed whitelist and marks them as the only valid values allowed.
		 */
		valid(value: any, ...values: any[]): T;
		valid(values: any[]): T;
		only(value: any, ...values : any[]): T;
		only(values: any[]): T;
		equal(value: any, ...values : any[]): T;
		equal(values: any[]): T;

		/**
		 * Blacklists a value
		 */
		invalid(value: any, ...values: any[]): T;
		invalid(values: any[]): T;
		disallow(value: any, ...values : any[]): T;
		disallow(values: any[]): T;
		not(value: any, ...values : any[]): T;
		not(values: any[]): T;

		/**
		 * Marks a key as required which will not allow undefined as value. All keys are optional by default.
		 */
		required(): T;

		/**
		 * Marks a key as optional which will allow undefined as values. Used to annotate the schema for readability as all keys are optional by default.
		 */
		optional(): T;

		/**
		 * Marks a key as forbidden which will not allow any value except undefined. Used to explicitly forbid keys.
		 */
		forbidden(): T;

		/**
		 * Marks a key to be removed from a resulting object or array after validation. Used to sanitize output.
		 */
		strip(): T;

		/**
		 * Annotates the key
		 */
		description(desc: string): T;

		/**
		 * Annotates the key
		 */
		notes(notes: string): T;
		notes(notes: string[]): T;

		/**
		 * Annotates the key
		 */
		tags(notes: string): T;
		tags(notes: string[]): T;

		/**
		 * Attaches metadata to the key.
		 */
		meta(meta: Object): T;

		/**
		 * Annotates the key with an example value, must be valid.
		 */
		example(value: any): T;

		/**
		 * Annotates the key with an unit name.
		 */
		unit(name: string): T;

		/**
		 * Overrides the global validate() options for the current key and any sub-key.
		 */
		options(options: ValidationOptions): T;

		/**
		 * Sets the options.convert options to false which prevent type casting for the current key and any child keys.
		 */
		strict(isStrict?: boolean): T;

		/**
		 * Sets a default value if the original value is undefined.
		 * @param value - the value.
		 *   value supports references.
		 *   value may also be a function which returns the default value.
		 *   If value is specified as a function that accepts a single parameter, that parameter will be a context
		 *    object that can be used to derive the resulting value. This clones the object however, which incurs some
		 *    overhead so if you don't need access to the context define your method so that it does not accept any
		 *    parameters.
		 *   Without any value, default has no effect, except for object that will then create nested defaults
		 *    (applying inner defaults of that object).
		 *
		 * Note that if value is an object, any changes to the object after default() is called will change the
		 *  reference and any future assignment.
		 *
		 * Additionally, when specifying a method you must either have a description property on your method or the
		 *  second parameter is required.
		 */
		default(value: any, description?: string): T;
		default(): T;

		/**
		 * Returns a new type that is the result of adding the rules of one type to another.
		 */
		concat(schema: T): T;

		/**
		 * Converts the type into an alternatives type where the conditions are merged into the type definition where:
		 */
		when<U>(ref: string, options: WhenOptions<U>): AlternativesSchema;
		when<U>(ref: Reference, options: WhenOptions<U>): AlternativesSchema;

		/**
		 * Overrides the key name in error messages.
		 */
		label(name: string): T;

		/**
		 * Outputs the original untouched value instead of the casted value.
		 */
		raw(isRaw?: boolean): T;

		/**
		 * Considers anything that matches the schema to be empty (undefined).
		 * @param schema - any object or joi schema to match. An undefined schema unsets that rule.
		 */
		empty(schema?: any) : T;
	}

	export interface BooleanSchema extends AnySchema<BooleanSchema> {

	}

	export interface NumberSchema extends AnySchema<NumberSchema> {
		/**
		 * Specifies the minimum value.
		 * It can also be a reference to another field.
		 */
		min(limit: number): NumberSchema;
		min(limit: Reference): NumberSchema;

		/**
		 * Specifies the maximum value.
		 * It can also be a reference to another field.
		 */
		max(limit: number): NumberSchema;
		max(limit: Reference): NumberSchema;

		/**
		 * Specifies that the value must be greater than limit.
		 * It can also be a reference to another field.
		 */
		greater(limit: number): NumberSchema;
		greater(limit: Reference): NumberSchema;

		/**
		 * Specifies that the value must be less than limit.
		 * It can also be a reference to another field.
		 */
		less(limit: number): NumberSchema;
		less(limit: Reference): NumberSchema;

		/**
		 * Requires the number to be an integer (no floating point).
		 */
		integer(): NumberSchema;

		/**
		 * Specifies the maximum number of decimal places where:
		 *  limit - the maximum number of decimal places allowed.
		 */
		precision(limit: number): NumberSchema;

		/**
		 * Specifies that the value must be a multiple of base.
		 */
		multiple(base: number): NumberSchema;

		/**
		 * Requires the number to be positive.
		 */
		positive(): NumberSchema;

		/**
		 * Requires the number to be negative.
		 */
		negative(): NumberSchema;
	}

	export interface StringSchema extends AnySchema<StringSchema> {
		/**
		 * Allows the value to match any whitelist of blacklist item in a case insensitive comparison.
		 */
		insensitive(): StringSchema;

		/**
		 * Specifies the minimum number string characters.
		 * @param limit - the minimum number of string characters required. It can also be a reference to another field.
		 * @param encoding - if specified, the string length is calculated in bytes using the provided encoding.
		 */
		min(limit: number, encoding?: string): StringSchema;
		min(limit: Reference, encoding?: string): StringSchema;

		/**
		 * Specifies the maximum number of string characters.
		 * @param limit - the maximum number of string characters allowed. It can also be a reference to another field.
		 * @param encoding - if specified, the string length is calculated in bytes using the provided encoding.
		 */
		max(limit: number, encoding?: string): StringSchema;
		max(limit: Reference, encoding?: string): StringSchema;

		/**
		 * Requires the number to be a credit card number (Using Lunh Algorithm).
		 */
		creditCard(): StringSchema;

		/**
		 * Specifies the exact string length required
		 * @param limit - the required string length. It can also be a reference to another field.
		 * @param encoding - if specified, the string length is calculated in bytes using the provided encoding.
		 */
		length(limit: number, encoding?: string): StringSchema;
		length(limit: Reference, encoding?: string): StringSchema;

		/**
		 * Defines a regular expression rule.
		 * @param pattern - a regular expression object the string value must match against.
		 * @param name - optional name for patterns (useful with multiple patterns). Defaults to 'required'.
		 */
		regex(pattern: RegExp, name?: string): StringSchema;

		/**
		 * Replace characters matching the given pattern with the specified replacement string where:
		 * @param pattern - a regular expression object to match against, or a string of which all occurrences will be replaced.
		 * @param replacement - the string that will replace the pattern.
		 */
		replace(pattern: RegExp, replacement: string): StringSchema;
		replace(pattern: string, replacement: string): StringSchema;

		/**
		 * Requires the string value to only contain a-z, A-Z, and 0-9.
		 */
		alphanum(): StringSchema;

		/**
		 * Requires the string value to only contain a-z, A-Z, 0-9, and underscore _.
		 */
		token(): StringSchema;

		/**
		 * Requires the string value to be a valid email address.
		 */
		email(options?: EmailOptions): StringSchema;

		/**
		 * Requires the string value to be a valid ip address.
		 */
		ip(options?: IpOptions): StringSchema;

		/**
		 * Requires the string value to be a valid RFC 3986 URI.
		 */
		uri(options?: UriOptions): StringSchema;

		/**
		 * Requires the string value to be a valid GUID.
		 */
		guid(): StringSchema;

		/**
		 * Requires the string value to be a valid hexadecimal string.
		 */
		hex(): StringSchema;

		/**
		 * Requires the string value to be a valid hostname as per RFC1123.
		 */
		hostname(): StringSchema;

		/**
		 * Requires the string value to be in valid ISO 8601 date format.
		 */
		isoDate(): StringSchema;

		/**
		 * Requires the string value to be all lowercase. If the validation convert option is on (enabled by default), the string will be forced to lowercase.
		 */
		lowercase(): StringSchema;

		/**
		 * Requires the string value to be all uppercase. If the validation convert option is on (enabled by default), the string will be forced to uppercase.
		 */
		uppercase(): StringSchema;

		/**
		 * Requires the string value to contain no whitespace before or after. If the validation convert option is on (enabled by default), the string will be trimmed.
		 */
		trim(): StringSchema;
	}

	export interface ArraySchema extends AnySchema<ArraySchema> {
		/**
		 * Allow this array to be sparse.
		 * enabled can be used with a falsy value to go back to the default behavior.
		 */
		sparse(enabled?: any): ArraySchema;

		/**
		 * Allow single values to be checked against rules as if it were provided as an array.
		 * enabled can be used with a falsy value to go back to the default behavior.
		 */
		single(enabled?: any): ArraySchema;

		/**
		 * List the types allowed for the array values.
		 * type can be an array of values, or multiple values can be passed as individual arguments.
		 * If a given type is .required() then there must be a matching item in the array.
		 * If a type is .forbidden() then it cannot appear in the array.
		 * Required items can be added multiple times to signify that multiple items must be found.
		 * Errors will contain the number of items that didn't match.
		 * Any unmatched item having a label will be mentioned explicitly.
		 *
		 * @param type - a joi schema object to validate each array item against.
		 */
		items(type: Schema, ...types: Schema[]): ArraySchema;
		items(types: Schema[]): ArraySchema;

		/**
		 * Lists the types in sequence order for the array values where:
		 * @param type - a joi schema object to validate against each array item in sequence order. type can be an array of values, or multiple values can be passed as individual arguments.
		 * If a given type is .required() then there must be a matching item with the same index position in the array. Errors will contain the number of items that didn't match. Any unmatched item having a label will be mentioned explicitly.
		 */
		ordered(type: Schema, ...types: Schema[]): ArraySchema;

		/**
		 * Specifies the minimum number of items in the array.
		 */
		min(limit: number): ArraySchema;

		/**
		 * Specifies the maximum number of items in the array.
		 */
		max(limit: number): ArraySchema;

		/**
		 * Specifies the exact number of items in the array.
		 */
		length(limit: number): ArraySchema;

		/**
		 * Requires the array values to be unique.
		 * Be aware that a deep equality is performed on elements of the array having a type of object,
		 * a performance penalty is to be expected for this kind of operation.
		 */
		unique(): ArraySchema;
	}

	export interface ObjectSchema extends AnySchema<ObjectSchema> {
		/**
		 * Sets the allowed object keys.
		 */
		keys(schema?: SchemaMap): ObjectSchema;

		/**
		 * Specifies the minimum number of keys in the object.
		 */
		min(limit: number): ObjectSchema;

		/**
		 * Specifies the maximum number of keys in the object.
		 */
		max(limit: number): ObjectSchema;

		/**
		 * Specifies the exact number of keys in the object.
		 */
		length(limit: number): ObjectSchema;

		/**
		 * Specify validation rules for unknown keys matching a pattern.
		 */
		pattern(regex: RegExp, schema: Schema): ObjectSchema;

		/**
		 * Defines an all-or-nothing relationship between keys where if one of the peers is present, all of them are required as well.
		 * @param peers - the key names of which if one present, all are required. peers can be a single string value,
		 * an array of string values, or each peer provided as an argument.
		 */
		and(peer1: string, ...peers: string[]): ObjectSchema;
		and(peers: string[]): ObjectSchema;

		/**
		 * Defines a relationship between keys where not all peers can be present at the same time.
		 * @param peers - the key names of which if one present, the others may not all be present.
		 * peers can be a single string value, an array of string values, or each peer provided as an argument.
		 */
		nand(peer1: string, ...peers: string[]): ObjectSchema;
		nand(peers: string[]): ObjectSchema;

		/**
		 * Defines a relationship between keys where one of the peers is required (and more than one is allowed).
		 */
		or(peer1: string, ...peers: string[]): ObjectSchema;
		or(peers: string[]): ObjectSchema;

		/**
		 * Defines an exclusive relationship between a set of keys. one of them is required but not at the same time where:
		 */
		xor(peer1: string, ...peers: string[]): ObjectSchema;
		xor(peers: string[]): ObjectSchema;

		/**
		 * Requires the presence of other keys whenever the specified key is present.
		 */
		with(key: string, peers: string): ObjectSchema;
		with(key: string, peers: string[]): ObjectSchema;

		/**
		 * Forbids the presence of other keys whenever the specified is present.
		 */
		without(key: string, peers: string): ObjectSchema;
		without(key: string, peers: string[]): ObjectSchema;

		/**
		 * Renames a key to another name (deletes the renamed key).
		 */
		rename(from: string, to: string, options?: RenameOptions): ObjectSchema;

		/**
		 * Verifies an assertion where.
		 */
		assert(ref: string, schema: Schema, message?: string): ObjectSchema;
		assert(ref: Reference, schema: Schema, message?: string): ObjectSchema;

		/**
		 * Overrides the handling of unknown keys for the scope of the current object only (does not apply to children).
		 */
		unknown(allow?: boolean): ObjectSchema;

		/**
		 * Requires the object to be an instance of a given constructor.
		 *
		 * @param constructor - the constructor function that the object must be an instance of.
		 * @param name - an alternate name to use in validation errors. This is useful when the constructor function does not have a name.
		 */
		type(constructor: Function, name?: string): ObjectSchema;

		/**
		 * Sets the specified children to required.
		 *
		 * @param children - can be a single string value, an array of string values, or each child provided as an argument.
		 *
		 *   var schema = Joi.object().keys({ a: { b: Joi.number() }, c: { d: Joi.string() } });
		 *   var requiredSchema = schema.requiredKeys('', 'a.b', 'c', 'c.d');
		 *
		 * Note that in this example '' means the current object, a is not required but b is, as well as c and d.
		 */
		requiredKeys(children: string): ObjectSchema;
		requiredKeys(children: string[]): ObjectSchema;
		requiredKeys(child:string, ...children: string[]): ObjectSchema;

		/**
		 * Sets the specified children to optional.
		 *
		 * @param children - can be a single string value, an array of string values, or each child provided as an argument.
		 *
		 * The behavior is exactly the same as requiredKeys.
		 */
		optionalKeys(children: string): ObjectSchema;
		optionalKeys(children: string[]): ObjectSchema;
		optionalKeys(child:string, ...children: string[]): ObjectSchema;
	}

	export interface BinarySchema extends AnySchema<BinarySchema> {
		/**
		 * Sets the string encoding format if a string input is converted to a buffer.
		 */
		encoding(encoding: string): BinarySchema;

		/**
		 * Specifies the minimum length of the buffer.
		 */
		min(limit: number): BinarySchema;

		/**
		 * Specifies the maximum length of the buffer.
		 */
		max(limit: number): BinarySchema;

		/**
		 * Specifies the exact length of the buffer:
		 */
		length(limit: number): BinarySchema;
	}

	export interface DateSchema extends AnySchema<DateSchema> {

		/**
		 * Specifies the oldest date allowed.
		 * Notes: 'now' can be passed in lieu of date so as to always compare relatively to the current date,
		 * allowing to explicitly ensure a date is either in the past or in the future.
		 * It can also be a reference to another field.
		 */
		min(date: Date): DateSchema;
		min(date: number): DateSchema;
		min(date: string): DateSchema;
		min(date: Reference): DateSchema;

		/**
		 * Specifies the latest date allowed.
		 * Notes: 'now' can be passed in lieu of date so as to always compare relatively to the current date,
		 * allowing to explicitly ensure a date is either in the past or in the future.
		 * It can also be a reference to another field.
		 */
		max(date: Date): DateSchema;
		max(date: number): DateSchema;
		max(date: string): DateSchema;
		max(date: Reference): DateSchema;

		/**
		 * Specifies the allowed date format:
		 * @param format - string or array of strings that follow the moment.js format.
		 */
		format(format: string): DateSchema;
		format(format: string[]): DateSchema;

		/**
		 * Requires the string value to be in valid ISO 8601 date format.
		 */
		iso(): DateSchema;


		/**
		 * Requires the value to be a timestamp interval from Unix Time.
		 * @param type - the type of timestamp (allowed values are unix or javascript [default])
		 */
		timestamp(type?: 'javascript' | 'unix'): DateSchema;
	}

	export interface FunctionSchema extends AnySchema<FunctionSchema> {

		/**
		 * Specifies the arity of the function where:
		 * @param n - the arity expected.
		 */
		arity(n: number): FunctionSchema;


		/**
		 * Specifies the minimal arity of the function where:
		 * @param n - the minimal arity expected.
		 */
		minArity(n: number): FunctionSchema;


		/**
		 * Specifies the minimal arity of the function where:
		 * @param n - the minimal arity expected.
		 */
		maxArity(n: number): FunctionSchema;

		/**
		 * Requires the function to be a Joi reference.
		 */
		ref(): FunctionSchema;
	}

	export interface AlternativesSchema extends AnySchema<FunctionSchema> {
		try(schemas: Schema[]): AlternativesSchema;
		try(type1: Schema, type2: Schema, ...types: Schema[]): AlternativesSchema;
		when<T>(ref: string, options: WhenOptions<T>): AlternativesSchema;
		when<T>(ref: Reference, options: WhenOptions<T>): AlternativesSchema;
	}

	export interface Terms {
		value: any;
		state: {
			key: string,
			path: string,
			parent: any
		};
		options: ValidationOptions;
	}

	export interface Rules {
		name: string;
		params?: ObjectSchema | { [key: string]: Schema };
		setup?: Function;
		validate?: Function;
		description: string | Function;
	}

	export interface Extension {
		name: string;
		base?: Schema;
		pre?: Function;
		language?: {};
		describe?: Function;
		rules?: Rules[];
	}

	// --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---

	/**
	 * Generates a schema object that matches any data type.
	 */
	export function any(): Schema;

	/**
	 * Generates a schema object that matches an array data type.
	 */
	export function array(): ArraySchema;

	/**
	 * Generates a schema object that matches a boolean data type (as well as the strings 'true', 'false', 'yes', and 'no'). Can also be called via bool().
	 */
	export function bool(): BooleanSchema;

	export function boolean(): BooleanSchema;

	/**
	 * Generates a schema object that matches a Buffer data type (as well as the strings which will be converted to Buffers).
	 */
	export function binary(): BinarySchema;

	/**
	 * Generates a schema object that matches a date type (as well as a JavaScript date string or number of milliseconds).
	 */
	export function date(): DateSchema;

	/**
	 * Generates a schema object that matches a function type.
	 */
	export function func(): FunctionSchema;

	/**
	 * Generates a schema object that matches a number data type (as well as strings that can be converted to numbers).
	 */
	export function number(): NumberSchema;

	/**
	 * Generates a schema object that matches an object data type (as well as JSON strings that parsed into objects).
	 */
	export function object(schema?: SchemaMap): ObjectSchema;

	/**
	 * Generates a schema object that matches a string data type. Note that empty strings are not allowed by default and must be enabled with allow('').
	 */
	export function string(): StringSchema;

	/**
	 * Generates a type that will match one of the provided alternative schemas
	 */
	export function alternatives(): AlternativesSchema;
	export function alternatives(types: Schema[]): AlternativesSchema;
	export function alternatives(type1: Schema, type2: Schema, ...types: Schema[]): AlternativesSchema;
	
	/**
	 * Generates a placeholder schema for a schema that you would provide with the fn.
	 * Supports the same methods of the any() type.
	 * This is mostly useful for recursive schemas
	 */
	export function lazy(cb: () => Schema): Schema;

	/**
	 * Validates a value using the given schema and options.
	 */
	export function validate<T>(value: T, schema: Schema, callback: (err: ValidationError, value: T) => void): void;
	export function validate<T>(value: T, schema: Object, callback: (err: ValidationError, value: T) => void): void;
	export function validate<T>(value: T, schema: Object, options?: ValidationOptions, callback?: (err: ValidationError, value: T) => void): ValidationResult<T>;

	/**
	 * Converts literal schema definition to joi schema object (or returns the same back if already a joi schema object).
	 */
	export function compile(schema: Object): Schema;

	/**
	 * Validates a value against a schema and throws if validation fails.
	 *
	 * @param value - the value to validate.
	 * @param schema - the schema object.
	 * @param message - optional message string prefix added in front of the error message. may also be an Error object.
	 */
	export function assert(value: any, schema: Schema, message?: string | Error): void;


	/**
	 * Validates a value against a schema, returns valid object, and throws if validation fails where:
	 *
	 * @param value - the value to validate.
	 * @param schema - the schema object.
	 * @param message - optional message string prefix added in front of the error message. may also be an Error object.
	 */
	export function attempt<T>(value: T, schema: Schema, message?: string | Error): T;


	/**
	 * Generates a reference to the value of the named key.
	 */
	export function ref(key: string, options?: ReferenceOptions): Reference;


	/**
	 * Checks whether or not the provided argument is a reference. It's especially useful if you want to post-process error messages.
	 */
	export function isRef(ref: any): boolean;


	/**
	 * Get a sub-schema of an existing schema based on a path. Path separator is a dot (.).
	 */
	export function reach(schema: Schema, path: string): Schema;


	/**
	 * Creates a new Joi instance customized with the extension(s) you provide included.
	 */
	export function extend(extention: Extension): any;

}