import AppKit
import Foundation
import SwiftData
import UniformTypeIdentifiers

/// Watches for sync files from the iOS MixBoard app.
/// Checks two locations:
///   1. A "MixBoard Sync" folder on the Desktop (for manual AirDrop/copy)
///   2. The iOS app's iCloud Drive container (if iCloud Drive sync is enabled)
@MainActor
final class SyncWatcher: ObservableObject {
    @Published var lastImportDate: Date?
    @Published var lastImportResult: String?
    @Published var hasPendingSync = false
    @Published var pendingSyncURL: URL?

    private var fileMonitor: DispatchSourceFileSystemObject?
    private var timer: Timer?
    private var lastKnownModDate: Date?

    /// All paths to check for sync files.
    var watchPaths: [URL] {
        var paths: [URL] = []

        // 1. Desktop/MixBoard Sync/ (for manual drops)
        let desktop = FileManager.default.urls(for: .desktopDirectory, in: .userDomainMask).first!
        paths.append(desktop.appendingPathComponent("MixBoard Sync/mixboard-playlists.json"))

        // 2. Documents/MixBoard Sync/
        let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
        paths.append(docs.appendingPathComponent("MixBoard Sync/mixboard-playlists.json"))

        // 3. iCloud Drive MixBoard app container
        // ~/Library/Mobile Documents/iCloud~com~mixboard~MixBoardiOS/Documents/Sync/mixboard-playlists.json
        let home = FileManager.default.homeDirectoryForCurrentUser
        let iCloudPath = home
            .appendingPathComponent("Library/Mobile Documents")
            .appendingPathComponent("com~apple~CloudDocs")  // generic iCloud Drive
            .appendingPathComponent("MixBoard/mixboard-playlists.json")
        paths.append(iCloudPath)

        return paths
    }

    /// Start polling for sync files (every 10 seconds).
    func startWatching() {
        timer = Timer.scheduledTimer(withTimeInterval: 10, repeats: true) { [weak self] _ in
            Task { @MainActor in
                self?.checkForSyncFile()
            }
        }
        // Check immediately
        checkForSyncFile()
    }

    func stopWatching() {
        timer?.invalidate()
        timer = nil
    }

    /// Check all watch paths for a sync file.
    func checkForSyncFile() {
        let fm = FileManager.default

        for url in watchPaths {
            guard fm.fileExists(atPath: url.path) else { continue }

            // Check if file is newer than last import
            if let attrs = try? fm.attributesOfItem(atPath: url.path),
               let modDate = attrs[.modificationDate] as? Date {
                if let lastKnown = lastKnownModDate, modDate <= lastKnown {
                    continue // Already processed this version
                }
                lastKnownModDate = modDate
                hasPendingSync = true
                pendingSyncURL = url
                return
            }
        }
    }

    /// Import from a specific sync file.
    func importSyncFile(_ url: URL, context: ModelContext) {
        do {
            let result = try SyncImporter.importFromFile(url, context: context)
            lastImportDate = Date()
            lastImportResult = result.summary
            hasPendingSync = false
            pendingSyncURL = nil
            print("SyncWatcher: \(result.summary)")
        } catch {
            lastImportResult = "Import failed: \(error.localizedDescription)"
            print("SyncWatcher: Import failed: \(error)")
        }
    }

    /// Import from the pending sync file.
    func importPending(context: ModelContext) {
        guard let url = pendingSyncURL else { return }
        importSyncFile(url, context: context)
    }

    /// Show an open panel to pick a sync file manually.
    func importManually(context: ModelContext) {
        let panel = NSOpenPanel()
        panel.title = "Import Playlists from iPhone"
        panel.allowedContentTypes = [.json]
        panel.allowsMultipleSelection = false
        panel.canChooseDirectories = false
        panel.message = "Select the mixboard-playlists.json file exported from MixBoard iOS"

        if panel.runModal() == .OK, let url = panel.url {
            importSyncFile(url, context: context)
        }
    }

    /// Create the sync drop folders so users know where to put the file.
    func createSyncFolders() {
        let fm = FileManager.default
        let desktop = fm.urls(for: .desktopDirectory, in: .userDomainMask).first!
        let syncFolder = desktop.appendingPathComponent("MixBoard Sync")
        try? fm.createDirectory(at: syncFolder, withIntermediateDirectories: true)
    }
}