//
//  AdminTelegramView.swift
//  FTStore Admin
//
//  The Telegram login the scraper runs on. The app never talks to Telegram —
//  it enqueues a command for the worker, which owns the TDLib session, and
//  polls the resulting state. So the code and the 2FA password are typed here
//  but only ever handled by your own server.
//

import SwiftUI

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

	@StateObject private var _status = AdminLoader<AdminTelegramStatus>()

	@State private var _code = ""
	@State private var _password = ""
	@State private var _busy = false
	@State private var _banner: String?

	private var _state: AdminTelegramStatus? { _status.value }

	var body: some View {
		Form {
			_statusSection

			if let banner = _banner {
				Section {
					Text(banner).font(.footnote).foregroundStyle(.secondary)
				}
			}

			if _state?.isWaitingForCode == true {
				_codeSection
			}

			if _state?.isWaitingForPassword == true {
				_passwordSection
			}

			_actionSection
			_diagnosticsSection
		}
		.navigationTitle("Telegram")
		.navigationBarTitleDisplayMode(.inline)
		.refreshable { await _reload() }
		// The worker picks a command up asynchronously, so the only way to see
		// "waiting_code" appear is to keep asking. The poll stops with the view.
		.task {
			while !Task.isCancelled {
				await _reload()
				try? await Task.sleep(nanoseconds: 3_000_000_000)
			}
		}
	}

	// MARK: Status

	@ViewBuilder
	private var _statusSection: some View {
		Section {
			if let state = _state {
				HStack(spacing: 12) {
					Image(systemName: _icon(state))
						.font(.title3)
						.foregroundStyle(_tint(state))
					VStack(alignment: .leading, spacing: 3) {
						Text(state.title)
							.font(.subheadline.weight(.semibold))
						Text(state.workerOnline ? "Worker online" : "Worker offline")
							.font(.caption)
							// Both branches spelled `Color.…`: a leading `.secondary`
							// resolves to `HierarchicalShapeStyle` and pins the
							// ternary to a type `.orange` doesn't exist in.
							.foregroundStyle(state.workerOnline ? Color.secondary : Color.orange)
					}
					Spacer()
					if state.busy || _busy { ProgressView() }
				}

				if let error = state.error, !error.isEmpty {
					Label(error, systemImage: "exclamationmark.triangle")
						.font(.footnote)
						.foregroundStyle(.red)
				}

				if let label = state.progressLabel, !label.isEmpty {
					VStack(alignment: .leading, spacing: 6) {
						Text(label)
							.font(.caption)
							.foregroundStyle(.secondary)
						if let current = state.progressCurrent, let total = state.progressTotal, total > 0 {
							ProgressView(value: Double(current), total: Double(total))
								.tint(AdminTheme.brand)
						}
					}
				}
			} else if let error = _status.errorMessage {
				AdminErrorRow(message: error) { Task { await _reload() } }
			} else {
				AdminLoadingRow()
			}
		} header: {
			Text("Connection")
		} footer: {
			Text("The worker holds the TDLib session. Nothing Telegram-related is stored on this device.")
		}
	}

	private func _icon(_ state: AdminTelegramStatus) -> String {
		switch state.state {
		case "ready": return "checkmark.seal.fill"
		case "error": return "exclamationmark.triangle.fill"
		case "waiting_code", "waiting_password": return "key.fill"
		case "connecting": return "arrow.triangle.2.circlepath"
		default: return "bolt.horizontal.circle"
		}
	}

	private func _tint(_ state: AdminTelegramStatus) -> Color {
		switch state.state {
		case "ready": return .green
		case "error": return .red
		case "waiting_code", "waiting_password": return .orange
		default: return .secondary
		}
	}

	// MARK: Input

	private var _codeSection: some View {
		Section {
			TextField("Verification code", text: $_code)
				.keyboardType(.numberPad)
				.textContentType(.oneTimeCode)

			Button("Submit Code") {
				_send(AdminRequest.TelegramAction(action: "code", code: _code.trimmingCharacters(in: .whitespaces)))
				_code = ""
			}
			.disabled(_code.trimmingCharacters(in: .whitespaces).isEmpty || _busy)
		} header: {
			Text("Verification Code")
		} footer: {
			Text("Telegram sent a login code to the configured phone number, in the Telegram app itself.")
		}
	}

	private var _passwordSection: some View {
		Section {
			SecureField("2FA password", text: $_password)
				.textContentType(.password)

			Button("Submit Password") {
				_send(AdminRequest.TelegramAction(action: "password", password: _password))
				_password = ""
			}
			.disabled(_password.isEmpty || _busy)
		} header: {
			Text("Two-Factor Password")
		} footer: {
			if let hint = _state?.passwordHint, !hint.isEmpty {
				Text("Hint: \(hint)")
			}
		}
	}

	// MARK: Actions

	@ViewBuilder
	private var _actionSection: some View {
		if let state = _state {
			Section {
				if !state.sessionReady {
					Button {
						_send(AdminRequest.TelegramAction(action: "connect"))
					} label: {
						Label("Connect", systemImage: "link")
					}
					.disabled(_busy || state.isWaitingForCode || state.isWaitingForPassword)
				}

				if state.sessionReady || state.state != "disconnected" {
					Button {
						_send(AdminRequest.TelegramAction(action: "disconnect"))
					} label: {
						Label("Disconnect", systemImage: "link.badge.plus")
					}
					.disabled(_busy)
				}

				AdminActionRow(
					title: "Reset Session",
					icon: "trash",
					detail: "Deletes the stored TDLib session, so you log in again from scratch",
					destructive: true,
					confirmation: "Delete the worker's Telegram session?"
				) {
					let status = try await session.send(
						.post,
						"/api/auth/telegram",
						body: AdminRequest.TelegramAction(action: "reset"),
						as: AdminTelegramStatus.self
					)
					await _reload()
					return .localized("Reset queued. State is now %@.", status.title.lowercased())
				}
			} header: {
				Text("Actions")
			}
		}
	}

	@ViewBuilder
	private var _diagnosticsSection: some View {
		if let state = _state {
			Section("Diagnostics") {
				LabeledContent("State", value: state.state)
				LabeledContent("Session ready", value: state.sessionReady ? "Yes" : "No")
				if let command = state.currentCommandType {
					LabeledContent("Running", value: command)
				}
				if let retries = state.retryCount, retries > 0 {
					LabeledContent("Retries", value: String(retries))
				}
				LabeledContent("Worker heartbeat", value: AdminFormat.relative(state.lastHeartbeatAt))
				LabeledContent("Last connected", value: AdminFormat.relative(state.lastConnectedAt))
				LabeledContent("Last authenticated", value: AdminFormat.relative(state.lastAuthAt))
			}
		}
	}

	// MARK: Networking

	private func _reload() async {
		await _status.load {
			try await session.get("/api/auth/telegram", as: AdminTelegramStatus.self)
		}
	}

	private func _send(_ action: AdminRequest.TelegramAction) {
		_busy = true
		_banner = nil
		Task { @MainActor in
			do {
				let status = try await session.send(
					.post,
					"/api/auth/telegram",
					body: action,
					as: AdminTelegramStatus.self
				)
				_banner = .localized("Queued. State is now %@.", status.title.lowercased())
			} catch {
				_banner = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
			}
			_busy = false
			await _reload()
		}
	}
}