import SwiftUI
import PhotosUI

struct GroupInfoView: View {
    @Binding var conversation: Conversation
    var appState: AppState
    var conversationListVM: ConversationListVM?
    @State private var showRenameSheet = false
    @State private var showLeaveConfirm = false
    @State private var showAddMember = false
    @State private var showRemoveConfirm = false
    @State private var showAvatarPicker = false
    @State private var newName = ""
    @State private var addMemberEmail = ""
    @State private var memberToRemove: ConversationMember?
    @State private var errorMessage: String?
    @State private var showError = false
    @State private var isUploadingAvatar = false
    @State private var groupAvatarData: Data?
    @Environment(\.dismiss) private var dismiss

    private var isCreator: Bool {
        conversation.createdBy == appState.currentUser?.id
    }

    private func refreshConversation() async {
        let convs = await appState.chatClient.listConversations()
        if let updated = convs.first(where: { $0.id == conversation.id }) {
            conversation = updated
        }
        await conversationListVM?.forceRefresh(chatClient: appState.chatClient)
    }

    var body: some View {
        NavigationStack {
            List {
                // Avatar section
                Section {
                    HStack {
                        Spacer()
                        VStack(spacing: 8) {
                            CircularAvatarView(
                                name: conversation.name ?? "Group",
                                imageData: groupAvatarData ?? conversationListVM?.avatarCache[conversation.id],
                                size: 64,
                                isGroup: true
                            )

                            Text(conversation.name ?? "Group")
                                .font(.title2.bold())

                            Text("\(conversation.members.count) members")
                                .font(.subheadline)
                                .foregroundStyle(.secondary)
                        }
                        Spacer()
                    }
                    .listRowBackground(Color.clear)
                }

                // Actions
                if isCreator {
                    Section {
                        Button("Add Member") {
                            addMemberEmail = ""
                            showAddMember = true
                        }

                        Button("Rename Group") {
                            newName = conversation.name ?? ""
                            showRenameSheet = true
                        }

                        Button {
                            showAvatarPicker = true
                        } label: {
                            HStack {
                                Text("Change Avatar")
                                if isUploadingAvatar {
                                    Spacer()
                                    ProgressView()
                                        .scaleEffect(0.8)
                                }
                            }
                        }
                        .disabled(isUploadingAvatar)
                    }
                }

                // Members
                Section("Members") {
                    ForEach(conversation.members) { member in
                        HStack {
                            CircularAvatarView(name: member.username, size: 32, isGroup: false)

                            VStack(alignment: .leading) {
                                Text(member.username)
                                    .font(.body)
                                Text(member.email)
                                    .font(.caption)
                                    .foregroundStyle(.secondary)
                            }

                            Spacer()

                            if member.userId == conversation.createdBy {
                                Text("Admin")
                                    .font(.caption)
                                    .foregroundStyle(.blue)
                            }
                        }
                        .contextMenu {
                            if isCreator && member.userId != appState.currentUser?.id {
                                Button("Remove from Group", role: .destructive) {
                                    memberToRemove = member
                                    showRemoveConfirm = true
                                }
                            }
                        }
                    }
                }

                // Leave / Delete
                Section {
                    Button("Leave Group", role: .destructive) {
                        showLeaveConfirm = true
                    }

                    if isCreator {
                        Button("Delete Group", role: .destructive) {
                            Task {
                                _ = await appState.chatClient.deleteConversation(convId: conversation.id)
                                dismiss()
                            }
                        }
                    }
                }
            }
            .navigationTitle("Group Info")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .topBarTrailing) {
                    Button("Done") { dismiss() }
                }
            }
            .alert("Leave Group?", isPresented: $showLeaveConfirm) {
                Button("Cancel", role: .cancel) {}
                Button("Leave", role: .destructive) {
                    Task {
                        _ = await appState.chatClient.leaveGroup(convId: conversation.id)
                        dismiss()
                    }
                }
            }
            .alert("Remove Member?", isPresented: $showRemoveConfirm) {
                Button("Cancel", role: .cancel) {}
                Button("Remove", role: .destructive) {
                    if let member = memberToRemove {
                        Task {
                            let (success, msg) = await appState.chatClient.removeMember(
                                convId: conversation.id, userId: member.userId
                            )
                            if success {
                                await refreshConversation()
                            } else {
                                errorMessage = msg
                                showError = true
                            }
                        }
                    }
                }
            } message: {
                if let member = memberToRemove {
                    Text("Remove \(member.username) from the group?")
                }
            }
            .alert("Add Member", isPresented: $showAddMember) {
                TextField("Email", text: $addMemberEmail)
                    .textInputAutocapitalization(.never)
                    .keyboardType(.emailAddress)
                Button("Cancel", role: .cancel) {}
                Button("Add") {
                    let email = addMemberEmail.trimmingCharacters(in: .whitespacesAndNewlines)
                    guard !email.isEmpty else { return }
                    Task {
                        let (success, msg) = await appState.chatClient.addMember(
                            convId: conversation.id, email: email
                        )
                        if success {
                            await refreshConversation()
                        } else {
                            errorMessage = msg
                            showError = true
                        }
                    }
                }
            }
            .alert("Rename Group", isPresented: $showRenameSheet) {
                TextField("Group Name", text: $newName)
                Button("Cancel", role: .cancel) {}
                Button("Rename") {
                    let trimmedName = newName.trimmingCharacters(in: .whitespacesAndNewlines)
                    guard !trimmedName.isEmpty else { return }
                    // Optimistic update - immediately reflect in UI
                    conversation.name = trimmedName
                    Task {
                        let (success, _) = await appState.chatClient.renameConversation(convId: conversation.id, name: trimmedName)
                        if success {
                            await refreshConversation()
                        } else {
                            // Revert on failure
                            await refreshConversation()
                        }
                    }
                }
            }
            .alert("Error", isPresented: $showError) {
                Button("OK") {}
            } message: {
                Text(errorMessage ?? "")
            }
            .sheet(isPresented: $showAvatarPicker) {
                AvatarPickerView { imageData in
                    isUploadingAvatar = true
                    Task {
                        let success = await appState.chatClient.updateGroupAvatar(
                            convId: conversation.id, imageData: imageData
                        )
                        isUploadingAvatar = false
                        if success {
                            // Update local avatar cache (memory + disk)
                            groupAvatarData = imageData
                            conversationListVM?.updateAvatar(convId: conversation.id, data: imageData)
                            await refreshConversation()
                        } else {
                            errorMessage = "Failed to update avatar"
                            showError = true
                        }
                    }
                }
            }
            .task {
                // Load current group avatar
                if groupAvatarData == nil, let cached = conversationListVM?.avatarCache[conversation.id] {
                    groupAvatarData = cached
                } else if groupAvatarData == nil {
                    groupAvatarData = await appState.chatClient.getGroupAvatar(convId: conversation.id)
                }
                await refreshConversation()
            }
        }
    }
}

// MARK: - Avatar Picker (PHPicker wrapper for avatar selection)

private struct AvatarPickerView: UIViewControllerRepresentable {
    let onImagePicked: (Data) -> Void

    func makeCoordinator() -> Coordinator {
        Coordinator(onImagePicked: onImagePicked)
    }

    func makeUIViewController(context: Context) -> PHPickerViewController {
        var config = PHPickerConfiguration()
        config.filter = .images
        config.selectionLimit = 1
        let picker = PHPickerViewController(configuration: config)
        picker.delegate = context.coordinator
        return picker
    }

    func updateUIViewController(_ uiViewController: PHPickerViewController, context: Context) {}

    class Coordinator: NSObject, PHPickerViewControllerDelegate {
        let onImagePicked: (Data) -> Void

        init(onImagePicked: @escaping (Data) -> Void) {
            self.onImagePicked = onImagePicked
        }

        func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
            guard let provider = results.first?.itemProvider,
                  provider.canLoadObject(ofClass: UIImage.self) else {
                picker.dismiss(animated: true)
                return
            }
            provider.loadObject(ofClass: UIImage.self) { [weak self] image, _ in
                guard let uiImage = image as? UIImage,
                      let data = uiImage.jpegData(compressionQuality: 0.8) else {
                    DispatchQueue.main.async { picker.dismiss(animated: true) }
                    return
                }
                DispatchQueue.main.async {
                    self?.onImagePicked(data)
                    picker.dismiss(animated: true)
                }
            }
        }
    }
}