//
//  DiscoverView.swift
//  Zyquo MLX
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//

import SwiftUI

/// Models › Discover: Featured catalog + live mlx-community search with
/// resumable downloads (charter Phase 6).
struct DiscoverView: View {
    @Bindable var model: AppModel
    @State private var query = ""
    @State private var results: [HubModel] = []
    @State private var isSearching = false
    @State private var searchError: String?
    @State private var downloads: [String: DownloadProgress] = [:]
    @State private var downloadErrors: [String: String] = [:]

    private var installedIDs: Set<String> {
        Set(model.models.compactMap(\.repoID))
    }

    var body: some View {
        VStack(spacing: 0) {
            searchField
                .padding(.horizontal, ZyquoTheme.spacing20)
                .padding(.bottom, ZyquoTheme.spacing12)

            ScrollView {
                LazyVStack(alignment: .leading, spacing: ZyquoTheme.spacing8) {
                    if let searchError {
                        Text(searchError)
                            .font(ZyquoTheme.captionFont)
                            .foregroundStyle(ZyquoTheme.danger)
                    }
                    if query.isEmpty {
                        Text("Featured — live-verified for this Mac")
                            .font(ZyquoTheme.headlineFont)
                            .foregroundStyle(ZyquoTheme.textPrimary)
                            .padding(.bottom, ZyquoTheme.spacing4)
                        ForEach(Catalog.featured) { entry in
                            DiscoverRow(
                                repoID: entry.id,
                                title: entry.name,
                                subtitle: "\(entry.params) · \(entry.quant) · \(ByteCountFormatter.string(fromByteCount: entry.weightBytes, countStyle: .file)) — \(entry.blurb)",
                                type: entry.type,
                                verdict: entry.verdict,
                                installed: installedIDs.contains(entry.id),
                                progress: downloads[entry.id],
                                error: downloadErrors[entry.id],
                                download: { download(repo: entry.id) },
                                cancel: { Task { await DownloadManager.shared.cancel(repo: entry.id) } })
                        }
                    } else if isSearching {
                        HStack {
                            ProgressView().controlSize(.small)
                            Text("Searching mlx models…")
                                .font(ZyquoTheme.captionFont)
                                .foregroundStyle(ZyquoTheme.textSecondary)
                        }
                        .frame(maxWidth: .infinity)
                        .padding(.top, ZyquoTheme.spacing32)
                    } else {
                        ForEach(results) { result in
                            DiscoverRow(
                                repoID: result.id,
                                title: result.id,
                                subtitle: "\(result.downloads.formatted()) downloads · \(result.likes) likes"
                                    + (result.gated ? " · gated" : ""),
                                type: result.modelType,
                                verdict: nil,
                                installed: installedIDs.contains(result.id),
                                progress: downloads[result.id],
                                error: downloadErrors[result.id],
                                download: { download(repo: result.id) },
                                cancel: { Task { await DownloadManager.shared.cancel(repo: result.id) } })
                        }
                        if results.isEmpty {
                            Text("No MLX models match “\(query)”.")
                                .font(ZyquoTheme.bodyFont)
                                .foregroundStyle(ZyquoTheme.textSecondary)
                                .frame(maxWidth: .infinity)
                                .padding(.top, ZyquoTheme.spacing32)
                        }
                    }
                }
                .padding(.horizontal, ZyquoTheme.spacing20)
                .padding(.bottom, ZyquoTheme.spacing20)
            }
        }
        .task(id: query) {
            guard !query.isEmpty else { return }
            isSearching = true
            searchError = nil
            try? await Task.sleep(for: .milliseconds(350)) // debounce
            guard !Task.isCancelled else { return }
            do {
                results = try await HubService.shared.search(query: query)
            } catch {
                searchError = error.localizedDescription
            }
            isSearching = false
        }
    }

    private var searchField: some View {
        HStack(spacing: ZyquoTheme.spacing8) {
            Image(systemName: "magnifyingglass")
                .foregroundStyle(ZyquoTheme.textTertiary)
            TextField("Search mlx-community models…", text: $query)
                .textFieldStyle(.plain)
                .font(ZyquoTheme.bodyFont)
        }
        .padding(.horizontal, ZyquoTheme.spacing12)
        .padding(.vertical, ZyquoTheme.spacing8)
        .background(ZyquoTheme.surfaceSecondary)
        .clipShape(RoundedRectangle(cornerRadius: ZyquoTheme.radiusSmall))
    }

    private func download(repo: String) {
        downloadErrors[repo] = nil
        Task {
            let events = await DownloadManager.shared.download(repo: repo)
            for await event in events {
                switch event {
                case .progress(let progress):
                    downloads[repo] = progress
                case .finished:
                    downloads[repo] = nil
                    await model.refresh()
                case .failed(let message):
                    downloads[repo] = nil
                    downloadErrors[repo] = message
                }
            }
        }
    }
}

private struct DiscoverRow: View {
    let repoID: String
    let title: String
    let subtitle: String
    let type: ModelType
    let verdict: MemoryVerdict?
    let installed: Bool
    let progress: DownloadProgress?
    let error: String?
    let download: () -> Void
    let cancel: () -> Void

    var body: some View {
        HStack(spacing: ZyquoTheme.spacing12) {
            VStack(alignment: .leading, spacing: ZyquoTheme.spacing2) {
                Text(title)
                    .font(ZyquoTheme.bodyFont.weight(.medium))
                    .foregroundStyle(ZyquoTheme.textPrimary)
                    .lineLimit(1)
                Text(error ?? subtitle)
                    .font(ZyquoTheme.captionFont)
                    .foregroundStyle(error != nil ? ZyquoTheme.danger : ZyquoTheme.textSecondary)
                    .lineLimit(2)
            }

            Spacer()

            TypeBadge(type: type)
            if let verdict {
                VerdictBadge(verdict: verdict)
            }

            if installed {
                StatusPill(text: "Installed", color: ZyquoTheme.success)
            } else if let progress {
                HStack(spacing: ZyquoTheme.spacing8) {
                    ProgressView(value: progress.fraction)
                        .frame(width: 90)
                    Text("\(Int(progress.fraction * 100))%")
                        .font(ZyquoTheme.monoSmallFont)
                        .foregroundStyle(ZyquoTheme.textSecondary)
                    Button(action: cancel) {
                        Image(systemName: "pause.circle")
                            .foregroundStyle(ZyquoTheme.textSecondary)
                    }
                    .buttonStyle(.plain)
                    .help("Pause (resumes from the same byte)")
                }
            } else {
                Button(action: download) {
                    Image(systemName: "arrow.down.circle.fill")
                        .font(.system(size: 20))
                        .foregroundStyle(ZyquoTheme.accent)
                }
                .buttonStyle(.plain)
                .help("Download")
            }
        }
        .padding(ZyquoTheme.spacing12)
        .zyquoCard()
    }
}