workoutsplus/WorkoutsPlus/Components/GenericItemManager.swift

//
//  GenericItemManager.swift
//  WorkoutsPlus
//
//  Created by Felix Förtsch on 15.11.24.
//

import SwiftUI
import SwiftData

// MARK: - Generic Item Manager
struct GenericItemManager<T: PersistentModel & Identifiable & CustomStringConvertible & EditableModel>: View {
		@Environment(\.modelContext) private var modelContext
		@Query private var items: [T]
		@State private var showingNewItemSheet = false
		@State private var newItem: T?
		
		let title: String
		let createNew: () -> T
		
		init(
				title: String,
				sortBy: SortDescriptor<T>,
				createNew: @escaping () -> T
		) {
				self.title = title
				self.createNew = createNew
				_items = Query(sort: [sortBy])
		}
		
		var body: some View {
				List {
						ForEach(items) { item in
								NavigationLink {
										ItemEditor(item: item)
								} label: {
										Text(String(describing: item))
								}
						}
						.onDelete(perform: deleteItems)
				}
				.navigationTitle(title)
				.toolbar {
						ToolbarItem(placement: .topBarTrailing) {
								Button {
										let newItem = createNew()
										modelContext.insert(newItem)
										showingNewItemSheet = true
										self.newItem = newItem
								} label: {
										Image(systemName: "plus")
								}
						}
				}
				.sheet(isPresented: $showingNewItemSheet) {
						if let newItem {
								NavigationStack {
										ItemEditor(item: newItem)
								}
						}
				}
		}
		
		private func deleteItems(offsets: IndexSet) {
				for index in offsets {
						modelContext.delete(items[index])
				}
		}
}

// MARK: - Item Editor
struct ItemEditor<T: PersistentModel & EditableModel>: View {
		@Environment(\.dismiss) private var dismiss
		@Bindable var item: T
		
		var body: some View {
				Form {
						ForEach(T.editableProperties) { property in
								if property.type == String.self {
										TextField(property.displayName, text: Binding(
												get: { property.get(item) },
												set: { property.set(item, $0) }
										))
								}
						}
				}
				.navigationTitle("New \(String(describing: T.self))")
				.navigationBarTitleDisplayMode(.inline)
				.toolbar {
						ToolbarItem(placement: .cancellationAction) {
								Button("Cancel") {
										dismiss()
								}
						}
						ToolbarItem(placement: .confirmationAction) {
								Button("Done") {
										dismiss()
								}
						}
				}
		}
}

// MARK: - Generic Assignment View
struct GenericAssignmentView<Owner: PersistentModel, Item: PersistentModel & Identifiable & CustomStringConvertible & EditableModel>: View {
		@Environment(\.modelContext) private var modelContext
		@Query private var availableItems: [Item]
		@Bindable var owner: Owner
		
		let title: String
		let getAssignedItems: (Owner) -> [Item]
		let assign: (Owner, Item) -> Void
		let unassign: (Owner, Item) -> Void
		let createNew: () -> Item
		let sortBy: SortDescriptor<Item>
		
		init(
				title: String,
				owner: Owner,
				sortBy: SortDescriptor<Item>,
				getAssignedItems: @escaping (Owner) -> [Item],
				assign: @escaping (Owner, Item) -> Void,
				unassign: @escaping (Owner, Item) -> Void,
				createNew: @escaping () -> Item
		) {
				self.title = title
				self.owner = owner
				self.sortBy = sortBy
				self.getAssignedItems = getAssignedItems
				self.assign = assign
				self.unassign = unassign
				self.createNew = createNew
				_availableItems = Query(sort: [sortBy])
		}
		
		var body: some View {
				List {
						Section {
								ForEach(availableItems) { item in
										let isAssigned = getAssignedItems(owner).contains(where: { $0.id == item.id })
										Button {
												if isAssigned {
														unassign(owner, item)
												} else {
														assign(owner, item)
												}
										} label: {
												HStack {
														Text(String(describing: item))
														Spacer()
														if isAssigned {
																Image(systemName: "checkmark")
														}
												}
										}
								}
						}
						Section {
								NavigationLink {
										GenericItemManager<Item>(
												title: title,
												sortBy: sortBy,
												createNew: createNew
										)
								} label: {
										Text("Manage \(title)")
								}
						}
				}
				.navigationTitle(title)
		}
}

// MARK: - Assignment Button
struct AssignmentButton<Owner: PersistentModel, Item: PersistentModel & Identifiable & CustomStringConvertible & EditableModel>: View {
		@Environment(\.modelContext) private var modelContext
		@Query private var availableItems: [Item]
		
		let title: String
		let owner: Owner
		let getAssignedItems: (Owner) -> [Item]
		let sortBy: SortDescriptor<Item>
		let assign: (Owner, Item) -> Void
		let unassign: (Owner, Item) -> Void
		let createNew: () -> Item
		
		init(
				title: String,
				owner: Owner,
				sortBy: SortDescriptor<Item>,
				getAssignedItems: @escaping (Owner) -> [Item],
				assign: @escaping (Owner, Item) -> Void,
				unassign: @escaping (Owner, Item) -> Void,
				createNew: @escaping () -> Item
		) {
				self.title = title
				self.owner = owner
				self.sortBy = sortBy
				self.getAssignedItems = getAssignedItems
				self.assign = assign
				self.unassign = unassign
				self.createNew = createNew
				_availableItems = Query(sort: [sortBy])
		}
		
		var body: some View {
				switch availableItems.count {
				case 0:
						NavigationLink {
								GenericItemManager<Item>(
										title: title,
										sortBy: sortBy,
										createNew: createNew
								)
						} label: {
								Text("Manage \(title)")
						}
						
				case 1...3:
						List {
								Section(header: Text("\(title)")) {
										ForEach(availableItems) { item in
												let isAssigned = getAssignedItems(owner).contains(where: { $0.id == item.id })
												Button {
														if isAssigned {
																unassign(owner, item)
														} else {
																assign(owner, item)
														}
												} label: {
														HStack {
																Text(String(describing: item))
																Spacer()
																if isAssigned {
																		Image(systemName: "checkmark")
																}
														}
												}
												.foregroundStyle(.primary)
										}
								}
								Section {
										NavigationLink {
												GenericItemManager<Item>(
														title: title,
														sortBy: sortBy,
														createNew: createNew
												)
										} label: {
												Text("Manage \(title)")
										}
								}
						}
						
				default:
						NavigationLink {
								GenericAssignmentView(
										title: title,
										owner: owner,
										sortBy: sortBy,
										getAssignedItems: getAssignedItems,
										assign: assign,
										unassign: unassign,
										createNew: createNew
								)
						} label: {
								HStack {
										Text(title)
										Spacer()
										Text("\(getAssignedItems(owner).count) of \(availableItems.count)")
												.foregroundStyle(.gray)
								}
						}
				}
		}
}

// Protocol for editable properties
protocol EditableModel {
		static var editableProperties: [EditableProperty] { get }
}

struct EditableProperty: Identifiable {
		let id = UUID()
		let displayName: String
		let type: Any.Type
		let get: (Any) -> String
		let set: (Any, String) -> Void
}