import SwiftUI

struct ContactsView: View {
    @Environment(HomeViewModel.self) private var homeVM
    @State private var searchText = ""

    private let primary = Color(red: 0.247, green: 0.396, blue: 0.678)

    private var filtered: [BankContact] {
        homeVM.contacts(matching: searchText)
    }

    private var grouped: [(String, [BankContact])] {
        let order = ["MIB", "BML", "FAHIPAY"]
        return order.compactMap { source in
            let group = filtered.filter { $0.source == source }
            return group.isEmpty ? nil : (source, group)
        }
    }

    var body: some View {
        NavigationStack {
            Group {
                if homeVM.isLoadingContacts && homeVM.contacts.isEmpty {
                    loadingView
                } else if filtered.isEmpty && homeVM.contactsError == nil && !homeVM.isLoadingContacts {
                    emptyView
                } else {
                    contactsList
                }
            }
            .navigationTitle("Contacts")
            .navigationBarTitleDisplayMode(.large)
            .searchable(text: $searchText, prompt: "Search name or account")
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    if homeVM.isLoadingContacts {
                        ProgressView().controlSize(.small)
                    } else {
                        Button {
                            Task { await homeVM.fetchContacts() }
                        } label: {
                            Image(systemName: "arrow.clockwise")
                        }
                    }
                }
            }
            .task {
                await homeVM.fetchContactsIfNeeded()
            }
            .refreshable {
                await homeVM.fetchContacts()
            }
        }
    }

    // MARK: - Contact list

    private var contactsList: some View {
        List {
            if let err = homeVM.contactsError {
                Section {
                    VStack(alignment: .leading, spacing: 6) {
                        Label("Fetch error", systemImage: "exclamationmark.triangle.fill")
                            .font(.caption.bold())
                            .foregroundStyle(.orange)
                        Text(err)
                            .font(.caption)
                            .foregroundStyle(.orange)
                            .fixedSize(horizontal: false, vertical: true)
                    }
                    .padding(.vertical, 4)
                }
            }
            ForEach(grouped, id: \.0) { source, contacts in
                Section(header: sectionHeader(source)) {
                    ForEach(contacts) { contact in
                        ContactRow(contact: contact) {
                            homeVM.pendingTransferContact = contact
                        }
                    }
                }
            }
        }
        .listStyle(.insetGrouped)
    }

    // MARK: - Section header

    private func sectionHeader(_ source: String) -> some View {
        HStack(spacing: 6) {
            Circle()
                .fill(bankColor(source))
                .frame(width: 8, height: 8)
            Text(bankFullName(source))
                .font(.caption.bold())
                .foregroundStyle(bankColor(source))
        }
    }

    // MARK: - Empty / loading

    private var emptyView: some View {
        VStack(spacing: 16) {
            Image(systemName: "person.badge.plus")
                .font(.system(size: 48))
                .foregroundStyle(.secondary)
            Text(searchText.isEmpty ? "No saved contacts" : "No results for \"\(searchText)\"")
                .font(.title3.bold())
                .foregroundStyle(.secondary)
            if searchText.isEmpty {
                Text("After a successful transfer, tap \"Save Contact\" on the receipt to add the recipient here.")
                    .font(.caption)
                    .foregroundStyle(.secondary)
                    .multilineTextAlignment(.center)
                    .padding(.horizontal, 40)
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }

    private var loadingView: some View {
        VStack(spacing: 16) {
            ProgressView()
            Text("Loading contacts…")
                .font(.subheadline)
                .foregroundStyle(.secondary)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }

    private func bankColor(_ source: String) -> Color {
        switch source {
        case "MIB":     return Color(red: 0.247, green: 0.396, blue: 0.678)
        case "BML":     return .blue
        case "FAHIPAY": return .purple
        default:        return .gray
        }
    }

    private func bankFullName(_ source: String) -> String {
        switch source {
        case "MIB":     return "Maldives Islamic Bank"
        case "BML":     return "Bank of Maldives"
        case "FAHIPAY": return "Fahipay"
        default:        return source
        }
    }
}

// MARK: - Contact row

struct ContactRow: View {
    let contact: BankContact
    var onSend: () -> Void

    private let primary = Color(red: 0.247, green: 0.396, blue: 0.678)

    var body: some View {
        HStack(spacing: 12) {
            avatarCircle
            VStack(alignment: .leading, spacing: 3) {
                Text(contact.displayName)
                    .font(.subheadline.bold())
                    .lineLimit(1)
                HStack(spacing: 6) {
                    Text(contact.benefAccount)
                        .font(.caption.monospaced())
                        .foregroundStyle(.secondary)
                    if let bank = contact.benefBankName, bank != "Maldives Islamic Bank", bank != "Bank of Maldives" {
                        Text("·")
                            .foregroundStyle(.secondary)
                        Text(bank)
                            .font(.caption2)
                            .foregroundStyle(.secondary)
                            .lineLimit(1)
                    }
                }
                typeBadge
            }
            Spacer()
            Button(action: onSend) {
                Image(systemName: "paperplane.fill")
                    .font(.subheadline)
                    .foregroundStyle(.white)
                    .frame(width: 32, height: 32)
                    .background(primary)
                    .clipShape(Circle())
            }
            .buttonStyle(.plain)
        }
        .padding(.vertical, 4)
        .contentShape(Rectangle())
    }

    private var avatarCircle: some View {
        ZStack {
            Circle()
                .fill(avatarColor.opacity(0.15))
                .frame(width: 40, height: 40)
            Text(initials)
                .font(.system(size: 15, weight: .semibold))
                .foregroundStyle(avatarColor)
        }
    }

    private var typeBadge: some View {
        Text(typeLabel)
            .font(.caption2.bold())
            .padding(.horizontal, 6)
            .padding(.vertical, 2)
            .background(typeColor.opacity(0.12))
            .foregroundStyle(typeColor)
            .clipShape(Capsule())
    }

    private var initials: String {
        let words = contact.displayName.split(separator: " ").prefix(2)
        return words.compactMap { $0.first }.map(String.init).joined()
    }

    private var avatarColor: Color {
        switch contact.source {
        case "MIB":     return Color(red: 0.247, green: 0.396, blue: 0.678)
        case "BML":     return .blue
        case "FAHIPAY": return .purple
        default:        return .gray
        }
    }

    private var typeLabel: String {
        switch contact.benefType {
        case "MIB":   return "MIB"
        case "LOCAL": return "IPS"
        case "SWIFT": return "SWIFT"
        case "BML":   return "BML"
        default:      return contact.benefType
        }
    }

    private var typeColor: Color {
        switch contact.benefType {
        case "SWIFT": return .orange
        case "LOCAL": return .green
        default:      return primary
        }
    }
}

#Preview {
    ContactsView()
        .environment(HomeViewModel())
}