//
//  DataController.swift
//  Feels
//
//  SwiftData controller replacing Core Data PersistenceController.
//

import SwiftData
import SwiftUI
import os.log

@MainActor
final class DataController: ObservableObject {
    private static let logger = Logger(subsystem: Bundle.main.bundleIdentifier ?? "com.tt.feels", category: "DataController")
    static let shared = DataController()

    private(set) var container: ModelContainer

    var modelContext: ModelContext {
        container.mainContext
    }


    // Listeners for data changes (keeping existing pattern)
    private var editedDataClosure = [() -> Void]()

    // Computed properties for earliest/latest entries
    var earliestEntry: MoodEntryModel? {
        var descriptor = FetchDescriptor<MoodEntryModel>(
            sortBy: [SortDescriptor(\.forDate, order: .forward)]
        )
        descriptor.fetchLimit = 1
        return try? modelContext.fetch(descriptor).first
    }

    var latestEntry: MoodEntryModel? {
        var descriptor = FetchDescriptor<MoodEntryModel>(
            sortBy: [SortDescriptor(\.forDate, order: .reverse)]
        )
        descriptor.fetchLimit = 1
        return try? modelContext.fetch(descriptor).first
    }

    private init() {
        container = SharedModelContainer.createWithFallback(useCloudKit: true)
    }


    // MARK: - Listener Management

    func addNewDataListener(closure: @escaping (() -> Void)) {
        editedDataClosure.append(closure)
    }

    func saveAndRunDataListeners() {
        save()
        for closure in editedDataClosure {
            closure()
        }
    }

    func save() {
        guard modelContext.hasChanges else { return }
        do {
            try modelContext.save()
        } catch {
            Self.logger.error("Failed to save context: \(error.localizedDescription)")
        }
    }

    /// Refresh data from disk to pick up changes made by extensions (widget/watch).
    /// Call this when app becomes active.
    func refreshFromDisk() {
        // SwiftData doesn't have a direct "refresh from disk" API.
        // We achieve this by:
        // 1. Rolling back any unsaved changes (ensures clean state)
        // 2. Triggering listeners to re-fetch data (which will read from disk)
        modelContext.rollback()

        // Notify listeners to re-fetch their data
        for closure in editedDataClosure {
            closure()
        }

        Self.logger.debug("Refreshed data from disk")
    }
}