import SwiftUI

struct PageDetailView: View {

    @Environment(\.language)
    private var language

    @EnvironmentObject
    private var content: Content

    @ObservedObject
    private var page: Page

    @State
    private var isGeneratingWebsite = false

    @State
    private var newId: String

    init(page: Page) {
        self.page = page
        self.newId = page.id
    }

    private let allowedCharactersInPostId = CharacterSet.alphanumerics.union(CharacterSet(charactersIn: "-")).inverted

    private var idExists: Bool {
        page.content.pages.contains { $0.id == newId }
    }

    private var containsInvalidCharacters: Bool {
        newId.rangeOfCharacter(from: allowedCharactersInPostId) != nil
    }

    var body: some View {
        ScrollView {
            VStack(alignment: .leading) {
                Button(action: generate) {
                    Text("Generate")
                }
                .disabled(isGeneratingWebsite)
                HStack {
                    TextField("", text: $newId)
                        .textFieldStyle(.roundedBorder)
                    Button("Update", action: setNewId)
                    .disabled(newId.isEmpty || containsInvalidCharacters || idExists)
                }
                .padding(.bottom)

                HStack {
                    Text("Draft")
                        .font(.headline)
                    Spacer()
                    Toggle("", isOn: $page.isDraft)
                        .toggleStyle(.switch)
                }
                .padding(.bottom)

                HStack {
                    Text("Start")
                        .font(.headline)
                    Spacer()
                    DatePicker("", selection: $page.startDate, displayedComponents: .date)
                        .datePickerStyle(.compact)
                        .padding(.bottom)
                }

                HStack(alignment: .firstTextBaseline) {
                    Text("Has end date")
                        .font(.headline)
                    Spacer()
                    Toggle("", isOn: $page.hasEndDate)
                        .toggleStyle(.switch)
                        .padding(.bottom)
                }

                if page.hasEndDate {
                    HStack(alignment: .firstTextBaseline) {
                        Text("End date")
                            .font(.headline)
                        Spacer()
                        DatePicker("", selection: $page.endDate, displayedComponents: .date)
                            .datePickerStyle(.compact)
                            .padding(.bottom)
                    }
                }

                LocalizedPageDetailView(page: page.localized(in: language))

            }
            .padding()
        }
    }

    private func generate() {
        guard content.settings.outputDirectoryPath != "" else {
            print("Invalid output path")
            return
        }
        let url = URL(fileURLWithPath: content.settings.outputDirectoryPath)

        guard FileManager.default.fileExists(atPath: url.path) else {
            print("Missing output folder")
            return
        }
        isGeneratingWebsite = true
        print("Generating page")
        DispatchQueue.global(qos: .userInitiated).async {
            let generator = WebsiteGenerator(
                content: content,
                language: language)
            if !generator.generate(page: page) {
                print("Generation failed")
            }
            DispatchQueue.main.async {
                isGeneratingWebsite = false
                print("Done")
            }
        }
    }

    private func setNewId() {
        guard page.update(id: newId) else {
            newId = page.id
            return
        }
        page.id = newId
    }
}

extension PageDetailView: MainContentView {

    init(item: Page) {
        self.init(page: item)
    }

    static let itemDescription = "a page"
}


#Preview {
    PageDetailView(page: .empty)
}