export declare namespace Tuple {
  /**
   * Constraint for the readonly array of element schemas used to define a
   * fixed-length `Tuple` schema.
   *
   * @category utility types
   * @since 3.10.0
   */
  export type Elements = ReadonlyArray<Constraint>

  type Type_<
    Elements,
    Out extends ReadonlyArray<any> = readonly []
  > = Elements extends readonly [infer Head, ...infer Tail] ?
    Head extends { readonly "Type": infer T } ?
      Head extends { readonly "~type.optionality": "optional" } ? Type_<Tail, readonly [...Out, T?]>
      : Type_<Tail, readonly [...Out, T]>
    : Out
    : Out

  /**
   * Computes the decoded tuple type for a tuple element schema array.
   *
   * **Details**
   *
   * Each element contributes its decoded `Type`; optional element schemas produce
   * optional tuple positions.
   *
   * @category utility types
   * @since 3.10.0
   */
  export type Type<E extends Elements> = Type_<E>

  type Iso_<
    Elements,
    Out extends ReadonlyArray<any> = readonly []
  > = Elements extends readonly [infer Head, ...infer Tail] ?
    Head extends { readonly "Iso": infer T } ?
      Head extends { readonly "~type.optionality": "optional" } ? Iso_<Tail, readonly [...Out, T?]>
      : Iso_<Tail, readonly [...Out, T]>
    : Out
    : Out

  /**
   * Computes the iso tuple type for a tuple element schema array from each
   * element schema's `Iso` type.
   *
   * @category utility types
   * @since 4.0.0
   */
  export type Iso<E extends Elements> = Iso_<E>

  type Encoded_<
    Elements,
    Out extends ReadonlyArray<any> = readonly []
  > = Elements extends readonly [infer Head, ...infer Tail] ?
    Head extends { readonly "Encoded": infer T } ?
      Head extends { readonly "~encoded.optionality": "optional" } ? Encoded_<Tail, readonly [...Out, T?]>
      : Encoded_<Tail, readonly [...Out, T]>
    : Out
    : Out

  /**
   * Computes the encoded tuple type for a tuple element schema array.
   *
   * **Details**
   *
   * Each element contributes its `Encoded` type; encoded-side optional element
   * schemas produce optional tuple positions.
   *
   * @category utility types
   * @since 3.10.0
   */
  export type Encoded<E extends Elements> = Encoded_<E>

  /**
   * Union of all decoding service requirements needed by the tuple element
   * schemas.
   *
   * @category utility types
   * @since 4.0.0
   */
  export type DecodingServices<E extends Elements> = E[number]["DecodingServices"]

  /**
   * Union of all encoding service requirements needed by the tuple element
   * schemas.
   *
   * @category utility types
   * @since 4.0.0
   */
  export type EncodingServices<E extends Elements> = E[number]["EncodingServices"]

  type MakeIn_<
    E,
    Out extends ReadonlyArray<any> = readonly []
  > = E extends readonly [infer Head, ...infer Tail] ?
    Head extends { "~type.make": infer T } ?
      Head extends
        { readonly "~type.optionality": "optional" } | { readonly "~type.constructor.default": "with-default" } ?
        MakeIn_<Tail, readonly [...Out, T?]> :
      MakeIn_<Tail, readonly [...Out, T]>
    : Out :
    Out

  /**
   * Computes the input tuple type accepted when constructing a tuple value.
   *
   * **Details**
   *
   * Each element uses its `~type.make` input type. Optional elements and elements
   * with constructor defaults produce optional tuple positions.
   *
   * @category utility types
   * @since 4.0.0
   */
  export type MakeIn<E extends Elements> = MakeIn_<E>
}

/**
 * Type-level representation returned by {@link Tuple}.
 *
 * @category models
 * @since 3.10.0
 */
export interface Tuple<Elements extends Tuple.Elements> extends
  BottomLazy<
    SchemaAST.Arrays,
    Tuple<Elements>
  >
{
  readonly "Type": Tuple.Type<Elements>
  readonly "Encoded": Tuple.Encoded<Elements>
  readonly "DecodingServices": Tuple.DecodingServices<Elements>
  readonly "EncodingServices": Tuple.EncodingServices<Elements>
  readonly "~type.make.in": Tuple.MakeIn<Elements>
  readonly "~type.make": Tuple.MakeIn<Elements>
  readonly "Iso": Tuple.Iso<Elements>
  readonly elements: Elements
  /**
   * Returns a new tuple with the elements modified by the provided function.
   *
   * **Details**
   *
   * Options:
   *
   * - `unsafePreserveChecks` - if `true`, keep any `.check(...)` constraints
   *   that were attached to the original union. Defaults to `false`.
   *
   *   **Warning**: This is an unsafe operation. Since `mapFields`
   *   transformations change the schema type, the original refinement functions
   *   may no longer be valid or safe to apply to the transformed schema. Only
   *   use this option if you have verified that your refinements remain correct
   *   after the transformation.
   */
  mapElements<To extends Tuple.Elements>(
    f: (elements: Elements) => To,
    options?: {
      readonly unsafePreserveChecks?: boolean | undefined
    } | undefined
  ): Tuple<Simplify<Readonly<To>>>
}

function makeTuple<Elements extends Tuple.Elements>(ast: SchemaAST.Arrays, elements: Elements): Tuple<Elements> {
  return make(ast, {
    elements,
    mapElements<To extends Tuple.Elements>(
      this: Tuple<Elements>,
      f: (elements: Elements) => To,
      options?: {
        readonly unsafePreserveChecks?: boolean | undefined
      } | undefined
    ): Tuple<Simplify<Readonly<To>>> {
      const elements = f(this.elements)
      return makeTuple(SchemaAST.tuple(elements, options?.unsafePreserveChecks ? this.ast.checks : undefined), elements)
    }
  })
}

/**
 * Defines a fixed-length tuple schema from an array of element schemas.
 *
 * **Example** (Defining a pair of string and number)
 *
 * ```ts
 * import { Schema } from "effect"
 *
 * const schema = Schema.Tuple([Schema.String, Schema.Number])
 *
 * const pair = Schema.decodeUnknownSync(schema)(["hello", 42])
 * console.log(pair)
 * // [ 'hello', 42 ]
 * ```
 *
 * @category constructors
 * @since 3.10.0
 */
export function Tuple<const Elements extends ReadonlyArray<Constraint>>(elements: Elements): Tuple<Elements> {
  return makeTuple(SchemaAST.tuple(elements), elements)
}