import SwiftUI

struct TaskPanelView: View {
    @ObservedObject var taskStore: TaskStore

    var body: some View {
        ScrollView {
            LazyVStack(alignment: .leading, spacing: 20) {
                if taskStore.sortedTasks.isEmpty {
                    emptyState
                } else {
                    Text(taskStore.activeCount > 0 ? "Hope is working on \(taskStore.activeCount) task\(taskStore.activeCount == 1 ? "" : "s"). You can keep talking." : "Results from the things you’ve asked Hope to work on.")
                        .font(.subheadline).foregroundStyle(.secondary)
                    ForEach(taskStore.sortedTasks) { task in
                        TaskCardView(task: task)
                    }
                }
            }
            .padding()
        }
        .navigationTitle("Activity")
        .background(Color(.systemGroupedBackground))
    }

    private var emptyState: some View {
        ContentUnavailableView {
            Label("A little help, in the background", systemImage: "checklist")
        } description: {
            Text("Ask Hope to research a topic or compare your options. Follow the progress and read the results here.")
        }
        .padding(.top, 48)
    }
}

struct TaskCardView: View {
    let task: TaskItem
    @State private var showSteps = false

    var body: some View {
        VStack(alignment: .leading, spacing: 14) {
            HStack {
                Label(statusTitle, systemImage: statusSymbol)
                    .font(.subheadline.weight(.medium))
                    .foregroundStyle(dotColor)
                Spacer()
                Text(task.createdAt, style: .time).font(.caption).foregroundStyle(.secondary)
            }
            Text(task.description).font(.headline).fixedSize(horizontal: false, vertical: true)
            if !task.steps.isEmpty {
                DisclosureGroup("\(task.steps.count) progress updates", isExpanded: $showSteps) {
                    VStack(alignment: .leading, spacing: 12) {
                    ForEach(task.steps) { step in
                        VStack(alignment: .leading, spacing: 4) {
                            Text(stepLabel(step.role))
                                .font(.caption.weight(.semibold)).foregroundStyle(.secondary)
                            Text(step.content ?? "")
                                .font(.subheadline).textSelection(.enabled)
                        }
                    }
                    }.padding(.top, 8)
                }
                .font(.subheadline)
            }
            if let result = task.result {
                block(result, color: .green, background: Color.green.opacity(0.12))
            }
            if let error = task.error {
                block(error, color: .red, background: Color.red.opacity(0.12))
            }
        }
        .padding(16)
        .frame(maxWidth: .infinity, alignment: .leading)
        .background(Color(.secondarySystemGroupedBackground), in: RoundedRectangle(cornerRadius: 16))
    }

    private var statusTitle: String {
        switch task.status {
        case .pending: "Queued"
        case .running: "In progress"
        case .completed: "Complete"
        case .failed: "Needs attention"
        }
    }

    private var statusSymbol: String {
        switch task.status {
        case .pending: "clock"
        case .running: "arrow.triangle.2.circlepath"
        case .completed: "checkmark.circle.fill"
        case .failed: "exclamationmark.circle"
        }
    }

    private var dotColor: Color {
        switch task.status {
        case .pending: return .gray
        case .running: return HopeStyle.tint
        case .completed: return .green
        case .failed: return .red
        }
    }

    private func block(_ text: String, color: Color, background: Color) -> some View {
        Text(text)
            .font(.body)
            .foregroundStyle(.primary)
            .textSelection(.enabled)
            .frame(maxWidth: .infinity, alignment: .leading)
    }

    private func stepLabel(_ role: String?) -> String {
        switch role {
        case "thinking": return "Thinking"
        case "tool_call": return "Tool"
        case "tool_result": return "Result"
        case "text": return "Note"
        default: return role ?? "Step"
        }
    }

    private func stepColor(_ role: String?) -> Color {
        switch role {
        case "thinking": return .blue
        case "tool_call": return .indigo
        case "tool_result": return .secondary
        default: return .primary
        }
    }
}

#Preview {
    NavigationStack {
        TaskPanelView(taskStore: {
            let store = TaskStore()
            #if DEBUG
            store.injectSampleEvents()
            #endif
            return store
        }())
    }
}