//
//  LibraryView.swift
//  Prisme
//
//  Author: Simon-Pierre Boucher <contact@spboucher.ai>
//

import SwiftUI

/// The library: saved excerpts and structured favourites. Content saved
/// here is native data with a source anchor — not a list of rotting URLs.
struct LibraryView: View {
    let library: LibraryStore
    let containers: IdentityContainerStore
    let onOpen: (URL, IdentityContainer.ID) -> Void

    @Environment(\.dismiss) private var dismiss
    @State private var section: Section = .excerpts

    private static let generated = Color(red: 0.55, green: 0.36, blue: 0.96)

    enum Section: String, CaseIterable {
        case excerpts = "Extraits"
        case pages = "Pages"
    }

    var body: some View {
        NavigationStack {
            VStack(spacing: 0) {
                Picker("Section", selection: $section) {
                    ForEach(Section.allCases, id: \.self) { section in
                        Text(section.rawValue).tag(section)
                    }
                }
                .pickerStyle(.segmented)
                .padding(.horizontal, Spacing.l)
                .padding(.bottom, Spacing.s)

                switch section {
                case .excerpts: excerptList
                case .pages: favoriteList
                }
            }
            .navigationTitle("Bibliothèque")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Fermer") { dismiss() }
                }
            }
        }
    }

    // MARK: - Excerpts

    @ViewBuilder
    private var excerptList: some View {
        let excerpts = library.excerpts
        if excerpts.isEmpty {
            ContentUnavailableView {
                Label("Aucun extrait", systemImage: "quote.opening")
            } description: {
                Text("Sélectionnez un passage dans une page, puis « Sauver l'extrait ». C'est le passage qui est gardé, avec sa source.")
            }
        } else {
            List {
                ForEach(excerpts, id: \.persistentModelID) { excerpt in
                    excerptRow(excerpt)
                        .swipeActions {
                            Button(role: .destructive) {
                                library.delete(excerpt)
                            } label: {
                                Label("Supprimer", systemImage: "trash")
                            }
                        }
                }
            }
            .listStyle(.plain)
        }
    }

    private func excerptRow(_ excerpt: Excerpt) -> some View {
        Button {
            open(excerpt.sourceURLString, containerID: excerpt.containerID)
        } label: {
            VStack(alignment: .leading, spacing: Spacing.s) {
                HStack(alignment: .top, spacing: Spacing.m) {
                    RoundedRectangle(cornerRadius: 2)
                        .fill(color(for: excerpt.containerID))
                        .frame(width: 3)
                    Text(excerpt.text)
                        .font(.callout)
                        .foregroundStyle(.primary)
                        .lineLimit(5)
                }
                HStack(spacing: Spacing.xs) {
                    if let section = excerpt.sectionTitle, !section.isEmpty {
                        Text(section)
                        Text("·")
                    }
                    Text(excerpt.sourceHost)
                    Text("·")
                    Text(excerpt.savedAt, style: .date)
                }
                .font(.caption)
                .foregroundStyle(.secondary)
                .lineLimit(1)
            }
            .padding(.vertical, Spacing.xs)
        }
        .buttonStyle(.plain)
        .accessibilityIdentifier("library.excerpt")
    }

    // MARK: - Structured favourites

    @ViewBuilder
    private var favoriteList: some View {
        let favorites = library.favorites
        if favorites.isEmpty {
            ContentUnavailableView {
                Label("Aucune page sauvée", systemImage: "bookmark")
            } description: {
                Text("Dans le lecteur, touchez le signet : la page est gardée en données natives — l'essentiel, le plan, la source.")
            }
        } else {
            List {
                ForEach(favorites, id: \.persistentModelID) { favorite in
                    favoriteRow(favorite)
                        .swipeActions {
                            Button(role: .destructive) {
                                library.delete(favorite)
                            } label: {
                                Label("Supprimer", systemImage: "trash")
                            }
                        }
                }
            }
            .listStyle(.plain)
        }
    }

    private func favoriteRow(_ favorite: StructuredFavorite) -> some View {
        Button {
            open(favorite.urlString, containerID: favorite.containerID)
        } label: {
            VStack(alignment: .leading, spacing: Spacing.xs) {
                HStack(spacing: Spacing.s) {
                    Circle()
                        .fill(color(for: favorite.containerID))
                        .frame(width: 8, height: 8)
                    Text(favorite.title)
                        .foregroundStyle(.primary)
                        .lineLimit(2)
                }
                if !favorite.gist.isEmpty {
                    HStack(alignment: .top, spacing: Spacing.xs) {
                        if favorite.isGenerated {
                            Image(systemName: "sparkles")
                                .font(.caption2)
                                .foregroundStyle(Self.generated)
                                .padding(.top, 2)
                        }
                        Text(favorite.gist)
                            .font(.caption)
                            .foregroundStyle(favorite.isGenerated ? AnyShapeStyle(Self.generated) : AnyShapeStyle(.secondary))
                            .italic(favorite.isGenerated)
                            .lineLimit(2)
                    }
                }
                HStack(spacing: Spacing.xs) {
                    Text(favorite.host)
                    Text("·")
                    let count = favorite.outlineTitles.count
                    Text(count > 1 ? "\(count) sections" : "\(count) section")
                    Text("·")
                    Text(favorite.savedAt, style: .date)
                }
                .font(.caption2)
                .foregroundStyle(.tertiary)
                .lineLimit(1)
            }
            .padding(.vertical, Spacing.xs)
        }
        .buttonStyle(.plain)
        .accessibilityIdentifier("library.favorite")
    }

    // MARK: - Helpers

    private func open(_ urlString: String, containerID: UUID) {
        guard let url = URL(string: urlString) else { return }
        onOpen(url, containerID)
        dismiss()
    }

    private func color(for containerID: UUID) -> Color {
        containers.container(for: containerID)?.color.color ?? .secondary
    }
}