// FeedManagerView.swift
// Jarvis — feed health & management. Healthy vs. needs-attention, live health
// updates over WebSocket, swipe to delete, add-feed sheet.

import SwiftUI

@MainActor
final class FeedManagerViewModel: ObservableObject {
    @Published var feeds: [Feed] = []
    @Published var isLoading = false
    @Published var error: String?

    private let api = APIClient.shared

    func load() async {
        isLoading = true
        error = nil
        do {
            feeds = try await api.fetchFeeds()
        } catch let e as APIError {
            error = e.errorDescription
        } catch {
            self.error = error.localizedDescription
        }
        isLoading = false
    }

    func add(url: String, name: String) async -> Bool {
        do {
            let feed = try await api.addFeed(url: url, name: name)
            feeds.append(feed)
            return true
        } catch let e as APIError {
            error = e.errorDescription
            return false
        } catch {
            self.error = error.localizedDescription
            return false
        }
    }

    func delete(_ feed: Feed) async {
        // Optimistic removal; restore on failure.
        let snapshot = feeds
        feeds.removeAll { $0.id == feed.id }
        do {
            try await api.deleteFeed(id: feed.id)
        } catch {
            feeds = snapshot
            self.error = (error as? APIError)?.errorDescription ?? error.localizedDescription
        }
    }

    /// Apply a live `feed.health` WebSocket event.
    func applyHealth(_ event: WSEvent) {
        guard let id = event.feedId, let health = event.health,
              let idx = feeds.firstIndex(where: { $0.id == id }) else { return }
        let f = feeds[idx]
        feeds[idx] = Feed(
            id: f.id, name: f.name, url: f.url, health: health,
            pollIntervalSeconds: f.pollIntervalSeconds,
            failureCount: event.failureCount ?? f.failureCount,
            lastFetchedAt: f.lastFetchedAt, articleCountToday: f.articleCountToday
        )
    }
}

struct FeedManagerView: View {
    @EnvironmentObject var ws: WebSocketManager
    @EnvironmentObject var settings: ServerSettings
    @StateObject private var vm = FeedManagerViewModel()

    @State private var query = ""
    @State private var showAdd = false
    @State private var showConnectivity = false

    private var filtered: [Feed] {
        guard !query.isEmpty else { return vm.feeds }
        return vm.feeds.filter {
            $0.name.localizedCaseInsensitiveContains(query) ||
            $0.url.localizedCaseInsensitiveContains(query)
        }
    }
    private var healthy: [Feed] { filtered.filter { $0.health == .active } }
    private var attention: [Feed] { filtered.filter { $0.health != .active } }

    var body: some View {
        ZStack {
            Palette.background.ignoresSafeArea()
            VStack(spacing: 0) {
                header
                serverCard
                searchBar
                feedList
            }
        }
        .presentationDragIndicator(.visible)
        .sheet(isPresented: $showAdd) {
            AddFeedSheet { url, name in
                await vm.add(url: url, name: name)
            }
        }
        .sheet(isPresented: $showConnectivity) {
            ConnectivityView()
        }
        .task { await vm.load() }
        .onReceive(NotificationCenter.default.publisher(for: .feedHealthChanged)) { note in
            if let event = note.object as? WSEvent { vm.applyHealth(event) }
        }
    }

    // MARK: - Header

    private var header: some View {
        HStack(alignment: .center) {
            JarvisWordmark(size: 26)
            Spacer()
            Button { showAdd = true } label: {
                HStack(spacing: 5) {
                    Image(systemName: "plus").font(.system(size: 13, weight: .heavy))
                    Text("Add feed").font(.system(size: 14, weight: .bold))
                }
                .foregroundStyle(.black)
                .padding(.horizontal, 14)
                .frame(height: 36)
                .background(Palette.orange)
                .clipShape(Capsule())
            }
        }
        .padding(.horizontal, 16)
        .padding(.top, 20)
        .padding(.bottom, 14)
    }

    // MARK: - Platform connection card

    private var serverCard: some View {
        Button { showConnectivity = true } label: {
            HStack(spacing: 12) {
                VStack(alignment: .leading, spacing: 4) {
                    Text("PLATFORM")
                        .font(.system(size: 9, weight: .bold, design: .monospaced))
                        .kerning(0.8)
                        .foregroundStyle(Palette.tertiaryText)
                    Text(settings.host ?? "not configured")
                        .font(.system(size: 14, weight: .bold, design: .monospaced))
                        .foregroundStyle(Palette.orange)
                }
                Spacer()
                HStack(spacing: 6) {
                    Circle().fill(ws.connectionState.dotColor).frame(width: 7, height: 7)
                    Text(ws.connectionState.label.uppercased())
                        .font(.system(size: 10, weight: .bold))
                        .kerning(0.6)
                        .foregroundStyle(ws.connectionState.isLive ? Color(hex: "33C25E") : Color(hex: "888888"))
                }
                Image(systemName: "chevron.right")
                    .font(.system(size: 12, weight: .bold))
                    .foregroundStyle(Palette.tertiaryText)
            }
            .padding(14)
            .background(Palette.surface)
            .clipShape(RoundedRectangle(cornerRadius: 12))
        }
        .buttonStyle(.plain)
        .padding(.horizontal, 16)
        .padding(.bottom, 12)
    }

    // MARK: - Search

    private var searchBar: some View {
        HStack(spacing: 10) {
            Image(systemName: "magnifyingglass")
                .font(.system(size: 14))
                .foregroundStyle(Palette.tertiaryText)
            TextField("", text: $query, prompt: Text("Search feeds").foregroundColor(Palette.tertiaryText))
                .font(.system(size: 15, weight: .regular))
                .foregroundStyle(Palette.primaryText)
                .autocorrectionDisabled()
                .textInputAutocapitalization(.never)
        }
        .padding(.horizontal, 14)
        .frame(height: 44)
        .background(Palette.surface2)
        .clipShape(RoundedRectangle(cornerRadius: 10))
        .padding(.horizontal, 16)
        .padding(.bottom, 8)
    }

    // MARK: - List

    private var feedList: some View {
        List {
            if vm.isLoading && vm.feeds.isEmpty {
                loadingRow
            }
            if !healthy.isEmpty {
                section(title: "HEALTHY", feeds: healthy)
            }
            if !attention.isEmpty {
                section(title: "NEEDS ATTENTION", feeds: attention)
            }
            if !vm.isLoading && filtered.isEmpty {
                emptyRow
            }
        }
        .listStyle(.plain)
        .scrollContentBackground(.hidden)
        .background(Palette.background)
        .refreshable { await vm.load() }
    }

    private func section(title: String, feeds: [Feed]) -> some View {
        Section {
            ForEach(feeds) { feed in
                FeedRowView(feed: feed)
                    .listRowBackground(Palette.background)
                    .listRowInsets(EdgeInsets(top: 6, leading: 16, bottom: 6, trailing: 16))
                    .listRowSeparatorTint(Palette.hairline)
                    .swipeActions(edge: .trailing) {
                        Button(role: .destructive) {
                            Task { await vm.delete(feed) }
                        } label: {
                            Label("Delete", systemImage: "trash")
                        }
                    }
            }
        } header: {
            Text(title)
                .font(.system(size: 10, weight: .bold, design: .monospaced))
                .kerning(0.8)
                .foregroundStyle(Palette.tertiaryText)
                .listRowInsets(EdgeInsets(top: 12, leading: 16, bottom: 6, trailing: 16))
        }
    }

    private var loadingRow: some View {
        ProgressView().tint(Palette.orange)
            .frame(maxWidth: .infinity)
            .listRowBackground(Palette.background)
            .listRowSeparator(.hidden)
    }

    private var emptyRow: some View {
        Text(query.isEmpty ? (vm.error ?? "No feeds configured.") : "No feeds match “\(query)”.")
            .font(.system(size: 13))
            .foregroundStyle(Palette.tertiaryText)
            .frame(maxWidth: .infinity, alignment: .leading)
            .listRowBackground(Palette.background)
            .listRowSeparator(.hidden)
    }
}

// MARK: - Feed row

struct FeedRowView: View {
    let feed: Feed

    var body: some View {
        HStack(spacing: 12) {
            Image(systemName: "dot.radiowaves.up.forward")
                .font(.system(size: 16, weight: .semibold))
                .foregroundStyle(Color(hex: "777777"))
                .frame(width: 24)

            VStack(alignment: .leading, spacing: 4) {
                Text(feed.name)
                    .font(.system(size: 15, weight: .bold))
                    .foregroundStyle(Palette.primaryText)
                    .lineLimit(1)
                Text(metaLine)
                    .font(.system(size: 11, weight: .regular, design: .monospaced))
                    .foregroundStyle(Palette.tertiaryText)
                    .lineLimit(1)
            }

            Spacer(minLength: 8)
            healthDot
        }
        .frame(minHeight: 44)
        .contentShape(Rectangle())
    }

    private var metaLine: String {
        let interval = pollText(feed.pollIntervalSeconds)
        let base = "Polls \(interval) · \(feed.articleCountToday) today"
        if feed.health == .failing {
            return base + " · ⚠ \(retryText)"
        }
        if feed.health == .dead {
            return base + " · dead"
        }
        return base
    }

    private var retryText: String {
        guard let last = feed.lastFetchedAt else { return "retrying" }
        let next = last.addingTimeInterval(Double(feed.pollIntervalSeconds))
        let secs = Int(next.timeIntervalSinceNow)
        return secs > 0 ? "retry \(secs)s" : "retrying…"
    }

    @ViewBuilder
    private var healthDot: some View {
        // Live-updating countdown for failing feeds.
        if feed.health == .failing {
            TimelineView(.periodic(from: .now, by: 1)) { _ in
                dot(color: Palette.healthFailing)
            }
        } else {
            dot(color: feed.health == .active ? Palette.healthActive : Palette.healthDead)
        }
    }

    private func dot(color: Color) -> some View {
        Circle()
            .fill(color)
            .frame(width: 10, height: 10)
            .overlay(Circle().stroke(color.opacity(0.9), lineWidth: 3).blur(radius: 2))
    }

    private func pollText(_ secs: Int) -> String {
        if secs % 3600 == 0 { return "every \(secs / 3600) hr" }
        if secs >= 60 { return "every \(secs / 60) min" }
        return "every \(secs) s"
    }
}