import SwiftUI
import UniformTypeIdentifiers
import SaplingCore
import SaplingWorkspace
import SaplingStorage
import SaplingLogging
import SaplingEditor
import SaplingRenderer
import SaplingUI

#if os(macOS)
import AppKit
#endif

@main
struct SaplingApplication: App {
    #if os(macOS)
    @NSApplicationDelegateAdaptor(SaplingAppDelegate.self) private var appDelegate
    #endif

    @StateObject private var model = SaplingAppModel(dependencies: .live())

    var body: some Scene {
        WindowGroup {
            MainWindow(model: model)
        }
        .commands {
            CommandGroup(after: .newItem) {
                Button("Open Workspace...") {
                    model.presentWorkspaceImporter()
                }
                .keyboardShortcut("o", modifiers: [.command, .shift])
            }
        }
        #if os(macOS)
        .windowStyle(.titleBar)
        .windowToolbarStyle(.unified)
        #endif

        #if os(macOS)
        Settings {
            SettingsView(
                configuration: $model.configuration,
                onSave: model.save(configuration:)
            )
        }
        #endif
    }
}

#if os(macOS)
private final class SaplingAppDelegate: NSObject, NSApplicationDelegate {
    func applicationDidFinishLaunching(_ notification: Notification) {
        NSApp.setActivationPolicy(.regular)
        NSApp.activate(ignoringOtherApps: true)
    }
}
#endif

@MainActor
private final class SaplingAppModel: ObservableObject {
    @Published var workspace: Workspace?
    @Published var workspaceSelection: WorkspaceTreeSelection?
    @Published var selectedProject: Project?
    @Published var selectedDocument: MarkdownDocument?
    @Published var editorViewModel: HybridMarkdownEditorViewModel?
    @Published var configuration: SaplingConfiguration
    @Published var editorErrorMessage: String?

    private let configurationStore: any ConfigurationStore
    private let workspaceManager: any WorkspaceManaging
    private let documentSessionStore: DocumentSessionStore
    private let logger: SaplingLogger

    init(dependencies: AppDependencies) {
        self.configurationStore = dependencies.configurationStore
        self.workspaceManager = dependencies.workspaceManager
        self.documentSessionStore = DocumentSessionStore()
        self.logger = dependencies.logger
        self.configuration = (try? dependencies.configurationStore.loadConfiguration()) ?? SaplingConfiguration()

        self.workspace = nil

        logger.info("Sapling application model initialized", category: .app)

        if let lastOpenedWorkspaceURL = configuration.lastOpenedWorkspaceURL {
            Task {
                await openWorkspace(at: lastOpenedWorkspaceURL)
            }
        }
    }

    func presentWorkspaceImporter() {
        #if os(macOS)
        let panel = NSOpenPanel()
        panel.title = "Open Workspace"
        panel.message = "Choose a folder to use as your Sapling workspace."
        panel.prompt = "Open"
        panel.canChooseDirectories = true
        panel.canChooseFiles = false
        panel.allowsMultipleSelection = false
        panel.canCreateDirectories = false
        panel.resolvesAliases = true

        guard panel.runModal() == .OK, let url = panel.url else { return }

        Task {
            await openWorkspace(at: url)
        }
        #else
        editorErrorMessage = "Workspace selection is currently available on macOS."
        #endif
    }

    func openWorkspace(at url: URL) async {
        let didStartAccessing = url.startAccessingSecurityScopedResource()
        defer {
            if didStartAccessing {
                url.stopAccessingSecurityScopedResource()
            }
        }

        do {
            let workspace = try await workspaceManager.openWorkspace(at: url)
            self.workspace = workspace
            workspaceSelection = nil
            selectedProject = nil
            selectedDocument = nil
            editorViewModel = nil
            documentSessionStore.closeAll()
            persistLastOpenedWorkspace(url)
            editorErrorMessage = nil
            logger.info("Opened workspace: \(workspace.name)", category: .workspace)
        } catch {
            editorErrorMessage = "Unable to open workspace \(url.lastPathComponent): \(error.localizedDescription)"
            logger.error("Failed to open workspace: \(error)", category: .workspace)
        }
    }

    func select(file: WorkspaceFile) {
        guard file.kind == .markdown else { return }
        workspaceSelection = .file(file.url)
        openDocument(at: file.url)
    }

    func openDocument(at url: URL) {
        let didStartAccessing = url.startAccessingSecurityScopedResource()
        defer {
            if didStartAccessing {
                url.stopAccessingSecurityScopedResource()
            }
        }

        do {
            let session = try documentSessionStore.openDocument(at: url)
            activate(session)
            editorErrorMessage = nil
            logger.info("Opened document: \(session.viewModel.document.title)", category: .editor)
        } catch {
            editorErrorMessage = "Unable to open \(url.lastPathComponent): \(error.localizedDescription)"
            logger.error("Failed to open document: \(error)", category: .editor)
        }
    }

    func saveSelectedDocument() {
        guard let editorViewModel else { return }

        do {
            try editorViewModel.save()
            selectedDocument = editorViewModel.document
            editorErrorMessage = nil
            logger.info("Saved document: \(editorViewModel.document.title)", category: .editor)
        } catch {
            editorErrorMessage = "Unable to save \(editorViewModel.document.title): \(error.localizedDescription)"
            logger.error("Failed to save document: \(error)", category: .editor)
        }
    }

    func select(project: Project) {
        selectedProject = project
        workspaceSelection = .project(project.repositoryURL)
        logger.info("Selected project: \(project.name)", category: .workspace)
    }

    func save(configuration: SaplingConfiguration) {
        do {
            try configurationStore.saveConfiguration(configuration)
            logger.debug("Saved configuration", category: .storage)
        } catch {
            logger.error("Failed to save configuration: \(error)", category: .storage)
        }
    }

    private func activate(_ session: MarkdownDocumentSession) {
        selectedDocument = session.viewModel.document
        editorViewModel = session.viewModel
        logger.info("Selected document: \(session.viewModel.document.title)", category: .editor)
    }

    private func persistLastOpenedWorkspace(_ url: URL) {
        configuration.lastOpenedWorkspaceURL = url
        configuration.recentWorkspaceURLs.removeAll { $0.standardizedFileURL == url.standardizedFileURL }
        configuration.recentWorkspaceURLs.insert(url, at: 0)
        configuration.recentWorkspaceURLs = Array(configuration.recentWorkspaceURLs.prefix(10))
        save(configuration: configuration)
    }
}

private struct MainWindow: View {
    @ObservedObject var model: SaplingAppModel
    @State private var isImportingMarkdown = false
    @State private var columnVisibility: NavigationSplitViewVisibility = .all

    var body: some View {
        NavigationSplitView(columnVisibility: $columnVisibility) {
            WorkspaceTreeView(
                workspace: model.workspace,
                selection: $model.workspaceSelection,
                onSelectFile: model.select(file:),
                onSelectProject: model.select(project:),
                onOpenWorkspace: model.presentWorkspaceImporter
            )
            .navigationSplitViewColumnWidth(min: 180, ideal: 220, max: 260)
        } detail: {
            if let editorViewModel = model.editorViewModel {
                HybridMarkdownEditor(
                    viewModel: editorViewModel,
                    renderer: MarkdownRenderer()
                )
                .navigationTitle(navigationTitle(for: editorViewModel))
            } else {
                EmptyEditorPlaceholder()
            }
        }
        .toolbar {
            ToolbarItemGroup {
                Button {
                    toggleSidebar()
                } label: {
                    Label("Toggle Sidebar", systemImage: "sidebar.leading")
                }
                .help("Toggle Sidebar")
                .keyboardShortcut("0", modifiers: [.command, .option])

                Button {
                    model.presentWorkspaceImporter()
                } label: {
                    Label("Open Workspace", systemImage: "folder.badge.plus")
                }
                .help("Open Workspace...")

                Button {
                    isImportingMarkdown = true
                } label: {
                    Label("Open Markdown", systemImage: "doc.badge.plus")
                }
                .help("Open Markdown")

                Button {
                    model.saveSelectedDocument()
                } label: {
                    Label("Save", systemImage: "square.and.arrow.down")
                }
                .help("Save")
                .disabled(model.editorViewModel?.hasUnsavedChanges != true)
                .keyboardShortcut("s", modifiers: .command)
            }
        }
        .fileImporter(
            isPresented: $isImportingMarkdown,
            allowedContentTypes: [.saplingMarkdown, .plainText],
            allowsMultipleSelection: false
        ) { result in
            switch result {
            case .success(let urls):
                guard let url = urls.first else { return }
                model.openDocument(at: url)
            case .failure(let error):
                model.editorErrorMessage = "Unable to open document: \(error.localizedDescription)"
            }
        }
        .alert(
            "Editor Error",
            isPresented: Binding(
                get: { model.editorErrorMessage != nil },
                set: { if !$0 { model.editorErrorMessage = nil } }
            )
        ) {
            Button("OK", role: .cancel) {
                model.editorErrorMessage = nil
            }
        } message: {
            Text(model.editorErrorMessage ?? "")
        }
    }

    private func navigationTitle(for viewModel: HybridMarkdownEditorViewModel) -> String {
        viewModel.hasUnsavedChanges ? "\(viewModel.document.title) *" : viewModel.document.title
    }

    private func toggleSidebar() {
        columnVisibility = columnVisibility == .all ? .detailOnly : .all
    }
}

private extension UTType {
    static var saplingMarkdown: UTType {
        UTType(filenameExtension: "md") ?? .plainText
    }
}