ElementHeaderFooter.swift

//
//  ElementHeaderFooter.swift
//  BlueprintUILists
//
//  Created by Kyle Van Essen on 10/9/20.
//

import ListableUI
import BlueprintUI


///
/// ⚠️ This method is soft-deprecated! Consider using `myElement.headerFooter(...)` instead.
///
/// Provides a way to create a `HeaderFooter` for your Blueprint elements without
/// requiring the creation of a new `BlueprintHeaderFooterContent` struct.
///
/// Most arguments on this method are not required – you must only
/// provide an input and an element provider.
///
/// ### Note
/// This initializer is helpful if you have to nest an existing element that needs to be used in
/// a single place, without needing to define an entirely new type.
///
/// If your header or footer is to be used in more than one place, it is recommended that you
/// create a `BlueprintHeaderFooterContent` struct to share logic to avoid duplicate code.
///
/// ### Example
/// ```
/// section.header = ElementHeaderFooter(album) { lhs, rhs in
///     lhs.value != rhs.value
/// }, element: { album in
///     AlbumElement(...)
/// }, background: { album in
///     ...
/// }, pressedBackground: album in
///     ...
/// }, configure: { header in
///     ...
/// }
/// ```
public func ElementHeaderFooter<Represented>(
    _ represented : Represented,
    
    isEquivalent : @escaping (Represented, Represented) -> Bool,
    
    element : @escaping (Represented) -> Element,
    background : @escaping (Represented) -> Element? = { _ in nil },
    pressedBackground : @escaping (Represented) -> Element? = { _ in nil },
    
    configure : (inout HeaderFooter<ElementHeaderFooterContent<Represented>>) -> () = { _ in }
    
) -> HeaderFooter<ElementHeaderFooterContent<Represented>>
{
    HeaderFooter(
        ElementHeaderFooterContent<Represented>(
            represented: represented,
            isEquivalentProvider: isEquivalent,
            elementProvider: element,
            backgroundProvider: background,
            pressedBackgroundProvider: pressedBackground
        ),
        configure: configure
    )
}

///
/// ⚠️ This method is soft-deprecated! Consider using `myElement.headerFooter(...)` instead.
///
/// Provides a way to create a `HeaderFooter` for your Blueprint elements without
/// requiring the creation of a new `BlueprintHeaderFooterContent` struct.
///
/// Most arguments on this method are not required – you must only
/// provide an input and an element provider.
///
/// Note
/// ----
/// This initializer is helpful if you have to nest an existing element that needs to be used in
/// a single place, without needing to define an entirely new type.
///
/// If your header or footer is to be used in more than one place, it is recommended that you
/// create a `BlueprintHeaderFooterContent` struct to share logic to avoid duplicate code.
///
/// Example
/// -------
/// ```
/// section.header = ElementHeaderFooter(album) { album in
///     AlbumElement(...)
/// }, background: { album in
///     ...
/// }, pressedBackground: album in
///     ...
/// }, configure: { header in
///     ...
/// }
/// ```
public func ElementHeaderFooter<Represented:Equatable>(
    _ represented : Represented,
                    
    element : @escaping (Represented) -> Element,
    background : @escaping (Represented) -> Element? = { _ in nil },
    pressedBackground : @escaping (Represented) -> Element? = { _ in nil },
    
    configure : (inout HeaderFooter<ElementHeaderFooterContent<Represented>>) -> () = { _ in }
    
) -> HeaderFooter<ElementHeaderFooterContent<Represented>>
{
    HeaderFooter(
        ElementHeaderFooterContent<Represented>(
            represented: represented,
            isEquivalentProvider: { $0 == $1 },
            elementProvider: element,
            backgroundProvider: background,
            pressedBackgroundProvider: pressedBackground
        ),
        configure: configure
    )
}

/// The `BlueprintHeaderFooterContent` type that is used to provide
/// a lightweight way to present an `Element`, without needing to provide an entirely
/// new `BlueprintHeaderFooterContent` type.
public struct ElementHeaderFooterContent<Represented> : BlueprintHeaderFooterContent
{
    public let represented : Represented

    let isEquivalentProvider : (Represented, Represented) -> Bool
    let elementProvider : (Represented) -> Element
    let backgroundProvider : (Represented) -> Element?
    let pressedBackgroundProvider : (Represented) -> Element?
    
    public func isEquivalent(to other: Self) -> Bool {
        self.isEquivalentProvider(self.represented, other.represented)
    }
    
    public var elementRepresentation : Element {
        self.elementProvider(self.represented)
    }
    
    public var background : Element? {
        self.backgroundProvider(self.represented)
    }
    
    public var pressedBackground : Element? {
        self.pressedBackgroundProvider(self.represented)
    }
}