// StoryDetailView.swift
// Jarvis — full story: consensus / conflict / coverage timeline.

import SwiftUI
import SwiftData

@MainActor
final class StoryDetailViewModel: ObservableObject {
    @Published var detail: StoryDetail?
    @Published var isLoading = false
    @Published var error: String?

    private let api = APIClient.shared

    func load(id: String) async {
        isLoading = true
        error = nil
        do {
            detail = try await api.fetchStory(id: id)
        } catch let e as APIError {
            error = e.errorDescription
        } catch {
            self.error = error.localizedDescription
        }
        isLoading = false
    }
}

struct StoryDetailView: View {
    let story: StorySummary

    @Environment(\.dismiss) private var dismiss
    @Environment(\.modelContext) private var modelContext
    @StateObject private var vm = StoryDetailViewModel()
    @Query private var cachedArticles: [CachedArticle]
    @Query private var readStories:  [ReadStory]
    @Query private var savedStories: [SavedStory]
    @State private var showShare = false

    // Prefer freshly-loaded detail; fall back to the summary we navigated with.
    private var topic: String { story.topic }
    private var score: Int { vm.detail?.signalScore ?? story.signalScore }
    private var headline: String { vm.detail?.headline ?? story.headline }
    private var summary: String { vm.detail?.summary ?? story.summary }
    private var consensus: String? { vm.detail?.consensus ?? story.consensus }
    private var conflict: String? { vm.detail?.conflict ?? story.conflict }
    private var sourceCount: Int { vm.detail?.sourceCount ?? story.sourceCount }
    private var timeline: [TimelineEntry] {
        (vm.detail?.timeline ?? []).sorted { $0.publishedAt < $1.publishedAt }
    }

    /// Unique source names in coverage order.
    private var sourceNames: [String] {
        var seen = Set<String>(); var out: [String] = []
        for e in timeline where !seen.contains(e.source) { seen.insert(e.source); out.append(e.source) }
        if out.isEmpty { out = story.sources.map(\.name) }
        return out
    }

    private var isRead:  Bool { readStories.contains  { $0.id == story.id } }
    private var isSaved: Bool { savedStories.contains { $0.id == story.id } }

    private var cachedIds: Set<String> {
        Set(cachedArticles.filter { $0.storyId == story.id }.map(\.id))
    }
    private var allCached: Bool {
        !timeline.isEmpty && timeline.allSatisfy { cachedIds.contains($0.articleId) }
    }

    var body: some View {
        ZStack {
            Color.black.ignoresSafeArea()
            ScrollView {
                VStack(alignment: .leading, spacing: 20) {
                    categoryRow
                    Text(headline)
                        .font(.system(size: 28, weight: .heavy))
                        .foregroundStyle(.white)
                        .fixedSize(horizontal: false, vertical: true)

                    if !summary.isEmpty {
                        Text(summary)
                            .font(.system(size: 15, weight: .regular))
                            .foregroundStyle(Color(hex: "9A9A9A"))
                            .lineSpacing(4)
                    }

                    SourceChips(names: sourceNames, total: sourceCount)

                    if allCached {
                        Text("All \(timeline.count) articles cached · available offline")
                            .font(.system(size: 12, weight: .bold))
                            .foregroundStyle(Color(hex: "6FBF6F"))
                    }

                    if let consensus { consensusBlock(consensus) }
                    if let conflict  { conflictBlock(conflict) }

                    timelineSection
                }
                .padding(.horizontal, 18)
                .padding(.vertical, 12)
            }
        }
        .navigationBarBackButtonHidden(true)
        .toolbar {
            ToolbarItem(placement: .topBarLeading) { backButton }
            ToolbarItemGroup(placement: .topBarTrailing) {
                Button { showShare = true } label: {
                    Image(systemName: "square.and.arrow.up")
                        .font(.system(size: 16, weight: .semibold))
                        .foregroundStyle(Color(hex: "888888"))
                }
                Button { toggleSave() } label: {
                    Image(systemName: isSaved ? "bookmark.fill" : "bookmark")
                        .font(.system(size: 16, weight: .semibold))
                        .foregroundStyle(isSaved ? Palette.orange : Color(hex: "888888"))
                }
                Button { toggleRead() } label: {
                    Image(systemName: isRead ? "checkmark.circle.fill" : "checkmark.circle")
                        .font(.system(size: 17, weight: .semibold))
                        .foregroundStyle(isRead ? Palette.orange : Color(hex: "888888"))
                }
            }
        }
        .toolbarBackground(Color.black, for: .navigationBar)
        .toolbarBackground(.visible, for: .navigationBar)
        .sheet(isPresented: $showShare) { ShareSheet(items: shareContent) }
        .task {
            markRead()
            await vm.load(id: story.id)
        }
    }

    // MARK: - Read / Save / Share

    private func markRead() {
        let id = story.id
        guard (try? modelContext.fetch(
            FetchDescriptor<ReadStory>(predicate: #Predicate { $0.id == id })))?.first == nil
        else { return }
        modelContext.insert(ReadStory(id: id))
        try? modelContext.save()
    }

    private func toggleRead() {
        let id = story.id
        if let row = (try? modelContext.fetch(
                FetchDescriptor<ReadStory>(predicate: #Predicate { $0.id == id })))?.first {
            modelContext.delete(row)
        } else {
            modelContext.insert(ReadStory(id: id))
        }
        try? modelContext.save()
    }

    private func toggleSave() {
        let id = story.id
        if let row = (try? modelContext.fetch(
                FetchDescriptor<SavedStory>(predicate: #Predicate { $0.id == id })))?.first {
            modelContext.delete(row)
        } else {
            // Ensure a CachedStory exists so SavedView can display it.
            let alreadyCached = (try? modelContext.fetch(
                FetchDescriptor<CachedStory>(predicate: #Predicate { $0.id == id })))?.first != nil
            if !alreadyCached { modelContext.insert(CachedStory(from: story)) }
            modelContext.insert(SavedStory(id: id))
        }
        try? modelContext.save()
    }

    private var shareContent: [Any] {
        var items: [Any] = ["\(headline)\n\n\(summary)\n\nvia Jarvis"]
        if let first = story.sources.first, let url = URL(string: first.url) {
            items.append(url)
        }
        return items
    }

    // MARK: - Pieces

    private var backButton: some View {
        Button { dismiss() } label: {
            HStack(spacing: 4) {
                Image(systemName: "chevron.left").font(.system(size: 15, weight: .bold))
                Text("Signal feed").font(.system(size: 16, weight: .regular))
            }
            .foregroundStyle(Palette.orange)
        }
    }

    private var categoryRow: some View {
        HStack(spacing: 10) {
            Text(Topic.label(topic).uppercased())
                .font(.system(size: 11, weight: .bold, design: .monospaced))
                .kerning(0.8)
                .foregroundStyle(Color(hex: "888888"))
            Text("·").foregroundStyle(Color(hex: "444444"))
            Text("\(score) signal")
                .font(.system(size: 11, weight: .bold, design: .monospaced))
                .foregroundStyle(Signal.scoreColor(score))
            Spacer()
        }
        .padding(.vertical, 6)
        .padding(.horizontal, 12)
        .background(Palette.surface)
        .clipShape(Capsule())
    }

    private func consensusBlock(_ text: String) -> some View {
        infoBlock(title: "CONSENSUS", text: text,
                  border: Palette.consensusBorder, fill: Palette.consensusFill,
                  titleColor: Palette.orange)
    }

    private func conflictBlock(_ text: String) -> some View {
        infoBlock(title: "CONFLICTING REPORTS", text: text,
                  border: Palette.conflictBorder, fill: Palette.conflictFill,
                  titleColor: Color(hex: "C25555"))
    }

    private func infoBlock(title: String, text: String, border: Color, fill: Color, titleColor: Color) -> some View {
        HStack(spacing: 0) {
            Rectangle().fill(border).frame(width: 3)
            VStack(alignment: .leading, spacing: 6) {
                Text(title)
                    .font(.system(size: 10, weight: .bold, design: .monospaced))
                    .kerning(0.8)
                    .foregroundStyle(titleColor)
                Text(text)
                    .font(.system(size: 14, weight: .regular))
                    .foregroundStyle(Color(hex: "C8C8C8"))
                    .lineSpacing(3)
                    .fixedSize(horizontal: false, vertical: true)
            }
            .padding(14)
            Spacer(minLength: 0)
        }
        .background(fill)
        .clipShape(RoundedRectangle(cornerRadius: 8))
    }

    private var timelineSection: some View {
        VStack(alignment: .leading, spacing: 0) {
            Text("COVERAGE TIMELINE")
                .font(.system(size: 10, weight: .bold, design: .monospaced))
                .kerning(0.8)
                .foregroundStyle(Color(hex: "555555"))
                .padding(.bottom, 14)

            if vm.isLoading && timeline.isEmpty {
                ProgressView().tint(Palette.orange).padding(.vertical, 20)
            } else if timeline.isEmpty {
                Text(vm.error ?? "No coverage available.")
                    .font(.system(size: 13))
                    .foregroundStyle(Color(hex: "555555"))
            } else {
                ForEach(Array(timeline.enumerated()), id: \.element.id) { index, entry in
                    NavigationLink(value: ArticleRoute(articleId: entry.articleId,
                                                       storyId: story.id,
                                                       parentHeadline: headline)) {
                        timelineRow(entry, isFirst: index == 0,
                                    isLast: index == timeline.count - 1,
                                    cached: cachedIds.contains(entry.articleId))
                    }
                    .buttonStyle(.plain)
                }
            }
        }
        .padding(.top, 8)
    }

    private func timelineRow(_ entry: TimelineEntry, isFirst: Bool, isLast: Bool, cached: Bool) -> some View {
        HStack(alignment: .top, spacing: 14) {
            // Node + connector
            VStack(spacing: 0) {
                Circle()
                    .fill(isFirst ? Palette.orange : Color(hex: "333333"))
                    .frame(width: 11, height: 11)
                    .overlay(Circle().stroke(Color.black, lineWidth: 2))
                if !isLast {
                    Rectangle().fill(Color(hex: "222222")).frame(width: 1.5)
                }
            }
            .frame(width: 11)

            VStack(alignment: .leading, spacing: 5) {
                HStack(spacing: 8) {
                    Text(entry.source)
                        .font(.system(size: 12, weight: .bold))
                        .foregroundStyle(isFirst ? Palette.orange : Color(hex: "999999"))
                    if entry.isBreaking {
                        Text("BREAKING")
                            .font(.system(size: 9, weight: .bold, design: .monospaced))
                            .foregroundStyle(.white)
                            .padding(.horizontal, 5).padding(.vertical, 2)
                            .background(Palette.conflictBorder)
                            .clipShape(Capsule())
                    }
                    Spacer()
                    Text(entry.publishedAt.clockShort)
                        .font(.system(size: 11, weight: .regular, design: .monospaced))
                        .foregroundStyle(Color(hex: "555555"))
                    if cached { CachedDot(size: 6) }
                }
                Text(entry.headline)
                    .font(.system(size: 15, weight: .regular))
                    .foregroundStyle(Color(hex: "D0D0D0"))
                    .fixedSize(horizontal: false, vertical: true)
                    .multilineTextAlignment(.leading)
            }
            .padding(.bottom, isLast ? 0 : 20)
        }
        .contentShape(Rectangle())
    }
}