import SwiftUI

/// Interactive save card shown by the share extension. On open it checks whether
/// the URL is already bookmarked, then lets the user set/edit tags, notes, and a
/// read-later flag before saving (new) or updating (existing) — never a duplicate.
struct ShareView: View {
    let url: String
    let initialTitle: String?
    let initialNotes: String
    /// Called when the extension should dismiss. `saved` is true after a successful
    /// write, false on cancel.
    let onClose: (_ saved: Bool) -> Void

    @State private var phase: Phase = .loading
    @State private var existing: Bookmark?
    @State private var title = ""
    @State private var tagText = ""
    @State private var notes = ""
    @State private var readLater = false
    @State private var createPodcast = false
    @State private var suggestedTags: [String] = []   // linkding auto_tags
    @State private var knownTags: Set<String> = []     // user's existing vocabulary (lowercased)
    @State private var aiSuggestions: [String] = []    // net-new AI ideas (not in vocabulary)
    @State private var suggesting = false
    @State private var errorMessage = ""

    @FocusState private var tagsFocused: Bool

    private let api: LinkdingAPI?

    init(url: String, initialTitle: String? = nil, initialNotes: String = "", onClose: @escaping (_ saved: Bool) -> Void) {
        self.url = url
        self.initialTitle = initialTitle
        self.initialNotes = initialNotes
        self.onClose = onClose
        self.api = ServerConfig.loadShared().map(LinkdingAPI.init)
        _title = State(initialValue: initialTitle ?? "")
        _notes = State(initialValue: initialNotes)
    }

    private enum Phase { case loading, editing, saving, done, failed }

    private static let relativeFormatter: RelativeDateTimeFormatter = {
        let f = RelativeDateTimeFormatter()
        f.unitsStyle = .abbreviated
        f.dateTimeStyle = .named
        return f
    }()

    var body: some View {
        VStack {
            Spacer()
            card
                .frame(maxWidth: 460)
                .padding(.horizontal, 20)
            Spacer()
        }
        .task { await check() }
    }

    @ViewBuilder
    private var card: some View {
        VStack(alignment: .leading, spacing: 16) {
            switch phase {
            case .loading:
                HStack(spacing: 12) {
                    ProgressView()
                    Text("Checking…").foregroundStyle(.secondary)
                }
                .frame(maxWidth: .infinity, alignment: .center)
                .padding(.vertical, 24)

            case .editing, .saving:
                header
                editor
                actions

            case .done:
                statusCard(icon: "checkmark.circle.fill", tint: .green,
                           text: existing != nil ? "Updated" : "Saved")

            case .failed:
                statusCard(icon: "xmark.circle.fill", tint: .red,
                           text: errorMessage.isEmpty ? "Something went wrong" : errorMessage)
            }
        }
        .padding(20)
        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 22, style: .continuous))
        .shadow(color: .black.opacity(0.15), radius: 24, y: 8)
    }

    // MARK: - Sections

    private var header: some View {
        VStack(alignment: .leading, spacing: 4) {
            if let existing {
                Label {
                    Text(existing.dateAdded == .distantPast
                         ? "Already saved"
                         : "Already saved · \(Self.relativeFormatter.localizedString(for: existing.dateAdded, relativeTo: Date()))")
                } icon: {
                    Image(systemName: "checkmark.circle.fill").foregroundStyle(.green)
                }
                .font(.subheadline.weight(.semibold))
            } else {
                Text("Save bookmark").font(.headline)
            }

            Text(title.isEmpty ? url : title)
                .font(.subheadline.weight(.medium))
                .lineLimit(2)
            Text(domain)
                .font(.caption)
                .foregroundStyle(.secondary)
        }
    }

    private var editor: some View {
        VStack(alignment: .leading, spacing: 14) {
            VStack(alignment: .leading, spacing: 6) {
                TextField("Tags (space separated)", text: $tagText)
                    .textInputAutocapitalization(.never)
                    .autocorrectionDisabled()
                    .focused($tagsFocused)
                    .textFieldStyle(.roundedBorder)

                if suggesting && aiSuggestions.isEmpty {
                    HStack(spacing: 6) {
                        ProgressView().controlSize(.small)
                        Text("Suggesting tags…")
                            .font(.caption)
                            .foregroundStyle(.secondary)
                    }
                }

                if !suggestionChips.isEmpty {
                    ScrollView(.horizontal, showsIndicators: false) {
                        HStack(spacing: 6) {
                            ForEach(suggestionChips, id: \.tag) { item in
                                Button { addTag(item.tag) } label: {
                                    Text(item.isAI ? "✨ \(item.tag)" : "+ \(item.tag)")
                                        .font(.caption.weight(.medium))
                                        .padding(.horizontal, 10)
                                        .padding(.vertical, 5)
                                        .background((item.isAI ? Color.purple : .blue).opacity(0.12), in: Capsule())
                                        .foregroundStyle(item.isAI ? Color.purple : .blue)
                                }
                                .buttonStyle(.plain)
                            }
                        }
                    }
                }
            }

            TextField("Notes", text: $notes, axis: .vertical)
                .lineLimit(1...3)
                .textFieldStyle(.roundedBorder)

            Toggle("Read later", isOn: $readLater)
                .font(.subheadline)

            Toggle(isOn: $createPodcast) {
                Label("Create podcast", systemImage: "headphones")
            }
            .font(.subheadline)
        }
    }

    private var actions: some View {
        HStack(spacing: 12) {
            Button("Cancel") { onClose(false) }
                .buttonStyle(.bordered)
                .frame(maxWidth: .infinity)

            Button {
                Task { await commit() }
            } label: {
                Group {
                    if phase == .saving { ProgressView().tint(.white) }
                    else { Text(existing != nil ? "Update" : "Save") }
                }
                .frame(maxWidth: .infinity)
            }
            .buttonStyle(.borderedProminent)
            .disabled(phase == .saving)
        }
        .padding(.top, 2)
    }

    private func statusCard(icon: String, tint: Color, text: String) -> some View {
        HStack(spacing: 10) {
            Image(systemName: icon).font(.title3).foregroundStyle(tint)
            Text(text).font(.headline)
        }
        .frame(maxWidth: .infinity, alignment: .center)
        .padding(.vertical, 16)
    }

    // MARK: - Derived

    private var domain: String { URL(string: url)?.host ?? url }

    /// Tappable suggestion chips: net-new AI ideas (✨) followed by linkding's
    /// auto_tags (+), excluding anything already in the field, de-duplicated.
    private var suggestionChips: [(tag: String, isAI: Bool)] {
        let current = Set(parsedTags.map { $0.lowercased() })
        var seen = Set<String>()
        var out: [(tag: String, isAI: Bool)] = []
        for tag in aiSuggestions + suggestedTags {
            let key = tag.lowercased()
            let isAI = aiSuggestions.contains { $0.lowercased() == key }
            if !current.contains(key) && seen.insert(key).inserted {
                out.append((tag, isAI))
            }
        }
        return out
    }

    private var parsedTags: [String] {
        tagText.split(whereSeparator: { $0 == " " || $0 == "," })
            .map { String($0) }
            .filter { !$0.isEmpty }
    }

    private func addTag(_ tag: String) {
        let trimmed = tagText.trimmingCharacters(in: .whitespaces)
        tagText = trimmed.isEmpty ? tag : trimmed + " " + tag
        tagText += " "
    }

    // MARK: - Networking

    private func check() async {
        guard let parsed = URL(string: url),
              let scheme = parsed.scheme?.lowercased(),
              scheme == "http" || scheme == "https",
              parsed.host?.isEmpty == false else {
            errorMessage = "No bookmarkable link found"
            phase = .failed
            return
        }
        guard let api else {
            errorMessage = "Open Marks first"
            phase = .failed
            return
        }
        do {
            let result = try await api.checkBookmark(url: url)
            if let bookmark = result.bookmark {
                existing = bookmark
                title = bookmark.displayTitle
                tagText = bookmark.tagNames.joined(separator: " ")
                notes = bookmark.description
                readLater = bookmark.unread
            } else {
                title = initialTitle ?? result.metadata?.title ?? ""
                suggestedTags = result.autoTags ?? []
                if notes.isEmpty {
                    notes = result.metadata?.description ?? initialNotes
                }
            }
            // Pre-enable the toggle when the current tags match the auto-rule.
            createPodcast = PodcastRequests.matchesAutoTag(parsedTags)
            phase = .editing
            await loadSuggestions()
        } catch {
            errorMessage = error.localizedDescription
            phase = .failed
        }
    }

    /// Fetches the user's existing tag vocabulary and AI tag ideas in parallel,
    /// then applies the hybrid behavior: auto-fill suggestions that match the
    /// existing vocabulary (new bookmarks only), surface the rest as chips.
    /// Best-effort — never throws, never blocks saving.
    private func loadSuggestions() async {
        guard let api else { return }
        suggesting = true
        defer { suggesting = false }

        async let vocabTask = api.fetchTags()
        let ai = await TagSuggester.suggest(url: url, title: title)
        let vocab = (try? await vocabTask) ?? []
        knownTags = Set(vocab.map { $0.lowercased() })

        if existing == nil {
            // Auto-fill AI tags the user already uses; high confidence, low surprise.
            let current = Set(parsedTags.map { $0.lowercased() })
            for tag in ai where knownTags.contains(tag.lowercased()) && !current.contains(tag.lowercased()) {
                addTag(tag)
            }
        }
        // Everything not in the vocabulary becomes a tappable ✨ chip.
        aiSuggestions = ai.filter { !knownTags.contains($0.lowercased()) }
    }

    private func commit() async {
        guard let api else { return }
        phase = .saving
        do {
            if let existing {
                let update = BookmarkUpdate(
                    url: existing.url,
                    title: existing.title,
                    description: notes,
                    tagNames: parsedTags,
                    unread: readLater,
                    shared: existing.shared
                )
                _ = try await api.updateBookmark(id: existing.id, update: update)
            } else {
                let create = BookmarkCreate(
                    url: url,
                    title: "",
                    description: notes,
                    tagNames: parsedTags,
                    isArchived: false,
                    unread: readLater,
                    shared: false
                )
                _ = try await api.createBookmark(create)
            }
            // Hand off podcast generation to the main app (the extension is too
            // short-lived to generate audio itself).
            if createPodcast || PodcastRequests.matchesAutoTag(parsedTags) {
                PodcastRequests.enqueue(url: url, title: title.isEmpty ? url : title)
            }
            phase = .done
            try? await Task.sleep(nanoseconds: 700_000_000)
            onClose(true)
        } catch {
            errorMessage = error.localizedDescription
            phase = .failed
            try? await Task.sleep(nanoseconds: 1_600_000_000)
            onClose(false)
        }
    }
}