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

import SwiftUI
import UniformTypeIdentifiers

/// Datasets section: import, validate, preview (charter §4.2).
struct DatasetsView: View {
    @Bindable var model: AppModel
    @State private var isImporting = false
    @State private var importError: String?

    var body: some View {
        Group {
            if model.datasets.isEmpty {
                EmptyStateView(
                    icon: "tablecells",
                    title: "No Datasets Yet",
                    message: "Import a JSONL file — chat conversations, prompt/completion pairs, or raw text. Zyquo validates every row, reports fixable issues, and splits it for training.",
                    actionLabel: "Import JSONL…",
                    action: { isImporting = true })
            } else {
                ScrollView {
                    LazyVStack(spacing: ZyquoTheme.spacing8) {
                        ForEach(model.datasets) { dataset in
                            DatasetRow(dataset: dataset)
                        }
                    }
                    .padding(ZyquoTheme.spacing20)
                }
                .toolbar {
                    ToolbarItem {
                        Button("Import JSONL…") { isImporting = true }
                    }
                }
            }
        }
        .fileImporter(
            isPresented: $isImporting,
            allowedContentTypes: [UTType(filenameExtension: "jsonl") ?? .json]
        ) { result in
            if case .success(let url) = result {
                Task {
                    do {
                        let gotAccess = url.startAccessingSecurityScopedResource()
                        defer { if gotAccess { url.stopAccessingSecurityScopedResource() } }
                        _ = try await DatasetService.shared.importJSONL(
                            from: url,
                            name: url.deletingPathExtension().lastPathComponent)
                        await model.refresh()
                    } catch {
                        importError = error.localizedDescription
                    }
                }
            }
        }
        .alert("Import Failed", isPresented: .constant(importError != nil)) {
            Button("OK") { importError = nil }
        } message: {
            Text(importError ?? "")
        }
    }
}

struct DatasetRow: View {
    let dataset: Dataset

    var body: some View {
        HStack(spacing: ZyquoTheme.spacing12) {
            Image(systemName: "tablecells")
                .font(.system(size: 18, weight: .light))
                .foregroundStyle(ZyquoTheme.slate)
                .frame(width: 32, height: 32)
                .background(ZyquoTheme.surfaceSecondary)
                .clipShape(RoundedRectangle(cornerRadius: ZyquoTheme.radiusSmall))

            VStack(alignment: .leading, spacing: ZyquoTheme.spacing2) {
                Text(dataset.name)
                    .font(ZyquoTheme.bodyFont.weight(.medium))
                    .foregroundStyle(ZyquoTheme.textPrimary)
                HStack(spacing: ZyquoTheme.spacing8) {
                    Text(dataset.format.displayName)
                    Text("train \(dataset.trainCount) · valid \(dataset.validCount)"
                        + (dataset.testCount > 0 ? " · test \(dataset.testCount)" : ""))
                    if let tokens = dataset.totalTokens {
                        Text("≈\(tokens.formatted()) tokens")
                    }
                }
                .font(ZyquoTheme.captionFont)
                .foregroundStyle(ZyquoTheme.textSecondary)
            }

            Spacer()

            Text(dataset.importedAt.formatted(date: .abbreviated, time: .omitted))
                .font(ZyquoTheme.captionFont)
                .foregroundStyle(ZyquoTheme.textTertiary)
        }
        .padding(ZyquoTheme.spacing12)
        .zyquoCard()
    }
}