//
//  AdminBackupView.swift
//  FTStore Admin
//
//  Settings → General → Backup & Restore, on the phone.
//
//  The file is a document, not a model: it is fetched and posted back as raw
//  bytes so a backup written by a newer FTStore Admin round-trips unchanged
//  instead of being silently narrowed to the fields this app happens to know.
//

import SwiftUI
import UIKit
import UniformTypeIdentifiers

struct AdminBackupView: View {
	@EnvironmentObject private var session: AdminSession

	@State private var _includeSecrets = false
	@State private var _exporting = false
	@State private var _importing = false
	@State private var _picking = false
	@State private var _banner: String?
	@State private var _failed = false

	var body: some View {
		Form {
			if let banner = _banner {
				Section {
					Label(banner, systemImage: _failed ? "exclamationmark.triangle" : "checkmark.circle")
						.font(.footnote)
						.foregroundStyle(_failed ? Color.red : Color.secondary)
				}
			}

			Section {
				Toggle("Include secrets", isOn: $_includeSecrets)

				Button {
					_export()
				} label: {
					HStack {
						Label("Export Settings", systemImage: "square.and.arrow.up")
						if _exporting {
							Spacer()
							ProgressView()
						}
					}
				}
				.disabled(_exporting)
			} header: {
				Text("Export")
			} footer: {
				Text(_includeSecrets
					? "The file will contain the Telegram API hash and both GitHub tokens. Treat it as a credential."
					: "Secrets are left out, so the file is safe to hand around. The export reads the saved settings, so save before exporting.")
			}

			Section {
				Button {
					_picking = true
				} label: {
					HStack {
						Label("Import Settings", systemImage: "square.and.arrow.down")
						if _importing {
							Spacer()
							ProgressView()
						}
					}
				}
				.disabled(_importing)
			} header: {
				Text("Restore")
			} footer: {
				Text("Importing merges into this install: what the file names is overwritten, anything it leaves out is kept, including credentials the file doesn't carry. Stored IPAs, the queue, scan progress and users are never touched.")
			}
		}
		.navigationTitle("Backup & Restore")
		.navigationBarTitleDisplayMode(.inline)
		.fileImporter(
			isPresented: $_picking,
			allowedContentTypes: [.json],
			allowsMultipleSelection: false
		) { result in
			_import(result)
		}
	}

	// MARK: Export

	private func _export() {
		_exporting = true
		_banner = nil
		_failed = false

		Task { @MainActor in
			do {
				let data = try await session.rawData(
					.get,
					"/api/settings/backup",
					query: ["secrets": _includeSecrets ? "1" : "0"]
				)

				// Written to the temp directory rather than Documents: the file
				// only has to survive long enough for the share sheet, and a
				// secrets-bearing export should not linger in a browsable
				// directory afterwards.
				let url = FileManager.default.temporaryDirectory
					.appendingPathComponent(Self._fileName())
				try data.write(to: url, options: .atomic)

				UIActivityViewController.show(activityItems: [url])
				_banner = .localized("Exported %@.", AdminFormat.bytes(Int64(data.count)))
			} catch {
				_failed = true
				_banner = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
			}
			_exporting = false
		}
	}

	private static func _fileName() -> String {
		let formatter = DateFormatter()
		formatter.dateFormat = "yyyy-MM-dd-HHmmss"
		return "ftstore-settings-\(formatter.string(from: Date())).json"
	}

	// MARK: Import

	private func _import(_ result: Result<[URL], Error>) {
		_banner = nil
		_failed = false

		guard case .success(let urls) = result, let url = urls.first else {
			if case .failure(let error) = result {
				_failed = true
				_banner = error.localizedDescription
			}
			return
		}

		_importing = true
		Task { @MainActor in
			let scoped = url.startAccessingSecurityScopedResource()
			defer { if scoped { url.stopAccessingSecurityScopedResource() } }

			do {
				let data = try Data(contentsOf: url)
				let response = try await session.rawData(
					.post,
					"/api/settings/backup",
					body: data,
					contentType: "application/json"
				)
				let ack = try? AdminJSON.decoder.decode(AdminAck.self, from: response)
				_banner = ack?.summary ?? "Settings imported."
			} catch {
				_failed = true
				_banner = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
			}
			_importing = false
		}
	}
}