//
//  PollVotingView.swift
//  SportsTime
//
//  View for ranking trips in a poll
//

import SwiftUI

struct PollVotingView: View {
    @Environment(\.dismiss) private var dismiss
    @Environment(\.colorScheme) private var colorScheme
    @State private var viewModel = PollVotingViewModel()
    @State private var showError = false

    let poll: TripPoll
    let existingVote: PollVote?
    var onVoteSubmitted: (() -> Void)?

    var body: some View {
        NavigationStack {
            VStack(spacing: 0) {
                // Instructions
                instructionsHeader

                // Reorderable list
                rankingList
                .listStyle(.plain)
                .scrollContentBackground(.hidden)
                .environment(\.editMode, .constant(.active))

                // Submit button
                submitButton
            }
            .themedBackground()
            .navigationTitle("Rank Trips")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Cancel") {
                        dismiss()
                    }
                }
            }
            .onAppear {
                viewModel.initializeRankings(
                    tripCount: poll.tripSnapshots.count,
                    existingVote: existingVote
                )
            }
            .alert("Error", isPresented: $showError) {
                Button("OK") {
                    viewModel.error = nil
                }
            } message: {
                if let error = viewModel.error {
                    Text(error.localizedDescription)
                }
            }
            .onChange(of: viewModel.error != nil) { _, hasError in
                showError = hasError
            }
            .onChange(of: viewModel.didSubmit) { _, didSubmit in
                if didSubmit {
                    onVoteSubmitted?()
                    dismiss()
                }
            }
        }
    }

    private var rankingList: some View {
        List {
            ForEach(Array(viewModel.rankings.enumerated()), id: \.element) { index, tripIndex in
                if tripIndex < poll.tripSnapshots.count {
                    RankingRow(
                        rank: index + 1,
                        trip: poll.tripSnapshots[tripIndex],
                        canMoveUp: index > 0,
                        canMoveDown: index < viewModel.rankings.count - 1,
                        onMoveUp: { viewModel.moveTripUp(at: index) },
                        onMoveDown: { viewModel.moveTripDown(at: index) }
                    )
                    .accessibilityHint("Drag to change ranking position, or use move up and move down buttons")
                    .listRowBackground(Theme.cardBackground(colorScheme))
                    .listRowSeparatorTint(Theme.surfaceGlow(colorScheme))
                }
            }
            .onMove { source, destination in
                viewModel.moveTrip(from: source, to: destination)
            }
        }
    }

    @ViewBuilder
    private var instructionsHeader: some View {
        VStack(spacing: 8) {
            Image(systemName: "arrow.up.arrow.down")
                .font(.title2)
                .foregroundStyle(Theme.warmOrange)
                .accessibilityLabel("Drag to reorder")

            Text("Drag to rank your preferences")
                .font(.headline)
                .foregroundStyle(Theme.textPrimary(colorScheme))

            Text("Your top choice should be at the top. You can drag, or use the move buttons.")
                .font(.subheadline)
                .foregroundStyle(Theme.textSecondary(colorScheme))
        }
        .padding()
        .frame(maxWidth: .infinity)
        .background(Theme.cardBackground(colorScheme))
    }

    @ViewBuilder
    private var submitButton: some View {
        Button {
            Task {
                if let existingVote {
                    await viewModel.updateVote(existingVote: existingVote)
                } else {
                    await viewModel.submitVote(pollId: poll.id)
                }
            }
        } label: {
            HStack {
                if viewModel.isLoading {
                    ProgressView()
                        .tint(.white)
                } else {
                    Text(existingVote != nil ? "Update Vote" : "Submit Vote")
                }
            }
            .frame(maxWidth: .infinity)
            .padding()
            .background(Theme.warmOrange)
            .foregroundStyle(.white)
            .font(.headline)
        }
        .disabled(viewModel.isLoading || !viewModel.canSubmit)
    }
}

// MARK: - Ranking Row

private struct RankingRow: View {
    @Environment(\.colorScheme) private var colorScheme
    let rank: Int
    let trip: Trip
    let canMoveUp: Bool
    let canMoveDown: Bool
    let onMoveUp: () -> Void
    let onMoveDown: () -> Void

    var body: some View {
        HStack(spacing: 12) {
            // Rank badge
            Text("\(rank)")
                .font(.headline)
                .foregroundStyle(.white)
                .frame(width: 28, height: 28)
                .background(rankColor)
                .clipShape(Circle())

            VStack(alignment: .leading, spacing: 2) {
                Text(trip.displayName)
                    .font(.headline)
                    .foregroundStyle(Theme.textPrimary(colorScheme))

                Text(tripSummary)
                    .font(.caption)
                    .foregroundStyle(Theme.textMuted(colorScheme))
            }

            Spacer()

            VStack(spacing: 6) {
                Button(action: onMoveUp) {
                    Image(systemName: "chevron.up")
                        .font(.caption.weight(.semibold))
                }
                .minimumHitTarget()
                .disabled(!canMoveUp)
                .accessibilityLabel("Move \(trip.displayName) up")

                Button(action: onMoveDown) {
                    Image(systemName: "chevron.down")
                        .font(.caption.weight(.semibold))
                }
                .minimumHitTarget()
                .disabled(!canMoveDown)
                .accessibilityLabel("Move \(trip.displayName) down")
            }
            .foregroundStyle(Theme.textSecondary(colorScheme))
        }
        .padding(.vertical, 4)
    }

    private var rankColor: Color {
        switch rank {
        case 1: return Theme.warmOrange
        case 2: return .blue
        case 3: return .green
        default: return .secondary
        }
    }

    private var tripSummary: String {
        let cities = trip.stops.map { $0.city }.joined(separator: " → ")
        return cities
    }
}

#Preview {
    PollVotingView(
        poll: TripPoll(
            title: "Test Poll",
            ownerId: "test",
            tripSnapshots: []
        ),
        existingVote: nil
    )
}