import SwiftUI
import OrgSocialKit

struct ComposeView: View {
    @Environment(\.dismiss) private var dismiss
    @State private var viewModel: ComposeViewModel
    @State private var showMentionWarning = false
    @State private var showDiscardDraftDialog = false
    @FocusState private var textFocused: Bool
    private let onPosted: (() -> Void)?

    init(replyTo: String? = nil, replyToNick: String? = nil, group: String? = nil, onPosted: (() -> Void)? = nil) {
        _viewModel = State(initialValue: ComposeViewModel(replyTo: replyTo, replyToNick: replyToNick, group: group))
        self.onPosted = onPosted
    }

    /// `:VISIBILITY: mention` is a UI hint telling clients to surface the post
    /// only to the users referenced by `[[org-social:URL][nick]]` links in the
    /// body (plus the author). Publishing mention-only with zero mention links
    /// produces a post nobody sees — almost always a mistake.
    private var mentionOnlyWithoutMentions: Bool {
        guard viewModel.visibility == .mention else { return false }
        // Picker-selected mentions are tracked in mentionMap, pre-encoding.
        // Manually-typed Org links are still accepted via the regex fallback.
        if !viewModel.mentionMap.isEmpty { return false }
        return viewModel.text.range(of: #"\[\[org-social:[^\]]+\]\[[^\]]+\]\]"#, options: .regularExpression) == nil
    }

    private var mentionCandidates: [MentionCandidate] {
        MentionDirectory.shared.candidates
    }

    private func submit() {
        Task {
            await viewModel.post()
            if viewModel.postedURL != nil {
                try? await Task.sleep(for: .seconds(1))
                onPosted?()
                dismiss()
            }
        }
    }

    var body: some View {
        NavigationStack {
            ScrollView {
                VStack(alignment: .leading, spacing: 0) {
                    // Text editor with @-mention autocomplete
                    MentionAutocompleteField(
                        text: $viewModel.text,
                        mentionMap: $viewModel.mentionMap,
                        candidates: mentionCandidates,
                        placeholder: "What's on your mind?",
                        focusBinding: $textFocused,
                        focusedValue: true
                    )
                    .background(Color(.secondarySystemBackground), in: RoundedRectangle(cornerRadius: 12))
                    .padding(.horizontal, 16)
                    .padding(.top, 16)

                    // Reply-to context
                    if let replyTo = viewModel.replyTo {
                        HStack(spacing: 8) {
                            Image(systemName: "arrowshape.turn.up.left.fill")
                                .font(.caption)
                                .foregroundStyle(.secondary)
                            if let nick = viewModel.replyToNick, !nick.isEmpty {
                                Text("@\(nick)")
                                    .font(.caption.weight(.semibold))
                                    .foregroundStyle(.secondary)
                                Text("·")
                                    .font(.caption)
                                    .foregroundStyle(.secondary)
                            }
                            Text(replyTo.components(separatedBy: "#").last ?? replyTo)
                                .font(.caption)
                                .foregroundStyle(.secondary)
                                .lineLimit(1)
                                .truncationMode(.middle)
                        }
                        .padding(.horizontal, 20)
                        .padding(.top, 10)
                    }

                    // Group context
                    if let group = viewModel.group {
                        HStack(spacing: 8) {
                            Image(systemName: "person.3.fill")
                                .font(.caption)
                                .foregroundStyle(.secondary)
                            Text(group.components(separatedBy: " ").first ?? group)
                                .font(.caption)
                                .foregroundStyle(.secondary)
                        }
                        .padding(.horizontal, 20)
                        .padding(.top, 10)
                    }

                    // Poll options
                    if viewModel.isPoll {
                        pollOptionsSection
                    }

                    // Options
                    VStack(spacing: 0) {
                        PostOptionToggleRow(icon: "chart.bar.xaxis", label: "Poll", isOn: $viewModel.isPoll)
                        Divider().padding(.leading, 52)

                        if viewModel.isPoll {
                            HStack(spacing: 12) {
                                Image(systemName: "calendar.badge.clock")
                                    .foregroundStyle(.secondary).frame(width: 24)
                                Text("Ends")
                                Spacer()
                                DatePicker("", selection: $viewModel.pollEndDate, in: Date()...)
                                    .labelsHidden()
                            }
                            .padding(.horizontal, 16).padding(.vertical, 12)
                            Divider().padding(.leading, 52)
                        }

                        PostOptionScheduleSection(isScheduled: $viewModel.isScheduled, scheduledDate: $viewModel.scheduledDate)
                        Divider().padding(.leading, 52)
                        PostOptionVisibilityRow(visibility: $viewModel.visibility)
                        Divider().padding(.leading, 52)
                        PostOptionTextFieldRow(icon: "globe", label: "Language", placeholder: "en", text: $viewModel.lang)
                        Divider().padding(.leading, 52)
                        PostOptionMoodRow(mood: $viewModel.mood)
                        Divider().padding(.leading, 52)
                        PostOptionTextFieldRow(icon: "number", label: "Tags", placeholder: "", text: $viewModel.tags)
                    }
                    .background(Color(.secondarySystemBackground), in: RoundedRectangle(cornerRadius: 12))
                    .padding(.horizontal, 16)
                    .padding(.top, 16)

                    // Visibility hint
                    if viewModel.visibility == .mention {
                        HStack(spacing: 6) {
                            Image(systemName: "info.circle")
                                .font(.caption)
                            Text("Only users you mention with [[org-social:URL][nick]] will see this post.")
                                .font(.caption)
                        }
                        .foregroundStyle(.secondary)
                        .padding(.horizontal, 20)
                        .padding(.top, 8)
                    }

                    // No feed configured warning
                    if !viewModel.hasFeedConfigured {
                        HStack(spacing: 8) {
                            Image(systemName: "exclamationmark.triangle.fill")
                                .foregroundStyle(.orange)
                            Text("Set your VFile Token in Settings before publishing.")
                                .font(.subheadline)
                                .foregroundStyle(.orange)
                        }
                        .padding()
                        .background(Color.orange.opacity(0.08), in: RoundedRectangle(cornerRadius: 10))
                        .padding(.horizontal, 16)
                        .padding(.top, 12)
                    }

                    // Status messages
                    if let error = viewModel.errorMessage {
                        HStack(spacing: 8) {
                            Image(systemName: "exclamationmark.triangle.fill")
                                .foregroundStyle(.red)
                            Text(error)
                                .font(.subheadline)
                                .foregroundStyle(.red)
                        }
                        .padding()
                        .background(Color.red.opacity(0.08), in: RoundedRectangle(cornerRadius: 10))
                        .padding(.horizontal, 16)
                        .padding(.top, 12)
                    }

                    if viewModel.postedURL != nil {
                        HStack(spacing: 8) {
                            Image(systemName: "checkmark.circle.fill")
                                .foregroundStyle(.green)
                            Text("Published!")
                                .font(.subheadline.weight(.semibold))
                                .foregroundStyle(.green)
                        }
                        .padding()
                        .background(Color.green.opacity(0.08), in: RoundedRectangle(cornerRadius: 10))
                        .padding(.horizontal, 16)
                        .padding(.top, 12)
                    }
                }
                .padding(.bottom, 32)
            }
            .navigationTitle(viewModel.replyTo != nil ? "Reply" : viewModel.group != nil ? "Group Post" : "New Post")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar { composeToolbar }
            .onAppear { textFocused = true }
            .task { await MentionDirectory.shared.refresh() }
            // Persist the in-progress draft on every keystroke (top-level
            // posts only; the model decides) so the body survives an
            // accidental Cancel or a backgrounded app.
            .onChange(of: viewModel.text) { _, _ in viewModel.saveDraftIfTopLevel() }
            .onDisappear { viewModel.saveDraftIfTopLevel() }
            .confirmationDialog(
                "Publish without mentions?",
                isPresented: $showMentionWarning,
                titleVisibility: .visible
            ) {
                Button("Publish anyway") { submit() }
                Button("Cancel", role: .cancel) {}
            } message: {
                Text("Mention-only posts are only shown to users linked with [[org-social:URL][nick]]. This post has no mention links, so no-one will see it.")
            }
            .confirmationDialog(
                "Discard this draft?",
                isPresented: $showDiscardDraftDialog,
                titleVisibility: .visible
            ) {
                Button("Keep draft") { dismiss() }
                Button("Discard", role: .destructive) {
                    viewModel.text = ""
                    viewModel.clearDraft()
                    dismiss()
                }
            } message: {
                Text("Keep the draft for later, or discard it now.")
            }
        }
    }

    private var pollOptionsSection: some View {
        VStack(alignment: .leading, spacing: 8) {
            Text("Options").font(.caption.weight(.medium)).foregroundStyle(.secondary)
                .padding(.horizontal, 20)
            ForEach(viewModel.pollOptions.indices, id: \.self) { i in
                HStack {
                    Image(systemName: "circle").foregroundStyle(.secondary)
                    TextField("Option \(i + 1)", text: $viewModel.pollOptions[i])
                    if viewModel.pollOptions.count > 2 {
                        Button { viewModel.pollOptions.remove(at: i) } label: {
                            Image(systemName: "minus.circle.fill").foregroundStyle(.red)
                        }
                    }
                }
                .padding(.horizontal, 16).padding(.vertical, 8)
                .background(Color(.secondarySystemBackground), in: RoundedRectangle(cornerRadius: 10))
                .padding(.horizontal, 16)
            }
            Button {
                if viewModel.pollOptions.count < 8 { viewModel.pollOptions.append("") }
            } label: {
                Label("Add option", systemImage: "plus.circle")
                    .font(.subheadline)
            }
            .padding(.horizontal, 20).padding(.vertical, 4)
        }
        .padding(.top, 16)
    }

    private func handleCancel() {
        // If the user has typed something, ask before closing so they can
        // choose between keeping the draft for later or discarding it.
        // Reply and group contexts skip the prompt because those drafts
        // aren't persisted anyway.
        let trimmed = viewModel.text.trimmingCharacters(in: .whitespacesAndNewlines)
        if viewModel.replyTo == nil, viewModel.group == nil, !trimmed.isEmpty {
            showDiscardDraftDialog = true
        } else {
            dismiss()
        }
    }

    @ToolbarContentBuilder
    private var composeToolbar: some ToolbarContent {
        ToolbarItem(placement: .cancellationAction) {
            Button("Cancel") { handleCancel() }
        }
        ToolbarItem(placement: .confirmationAction) {
            if viewModel.isPosting {
                ProgressView()
            } else {
                Button("Post") {
                    if mentionOnlyWithoutMentions {
                        showMentionWarning = true
                    } else {
                        submit()
                    }
                }
                .fontWeight(.semibold)
                .disabled(!viewModel.canPost)
            }
        }
    }
}