//
//  TONView.swift
//  OS Vault
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//

import SwiftUI
import BigInt

/// TON panel: TON + USDT (jetton) balances, receive, send, testnet/mainnet
/// switch. USDT lives on mainnet only (no official testnet jetton).
struct TONView: View {
    @EnvironmentObject var app: AppState
    @Environment(\.dismiss) private var dismiss

    enum Mode { case overview, receive, send }
    @State private var mode: Mode = .overview

    @State private var sendUSDT = false
    @State private var recipient = ""
    @State private var amountInput = ""
    @State private var prepared: TONService.PreparedTONSend?
    @State private var password = ""
    @State private var busy = false
    @State private var sentRef: String?
    @State private var errorMessage: String?

    var body: some View {
        VStack(alignment: .leading, spacing: 16) {
            header
            switch mode {
            case .overview: overview
            case .receive: receive
            case .send: send
            }
        }
        .padding(24)
        .frame(width: 470)
    }

    private var header: some View {
        HStack {
            Text("TON").font(.title2.bold())
            Spacer()
            Text(app.tonNetwork.isTestnet ? "TESTNET" : "MAINNET")
                .font(.caption.weight(.bold))
                .padding(.horizontal, 10).padding(.vertical, 4)
                .background(app.tonNetwork.isTestnet ? Color.orange.opacity(0.25) : Color.cyan.opacity(0.2))
                .foregroundStyle(app.tonNetwork.isTestnet ? Color.orange : Color.cyan)
                .clipShape(Capsule())
            Button("Done") { dismiss() }
        }
    }

    // MARK: - Overview

    private var overview: some View {
        VStack(alignment: .leading, spacing: 14) {
            VStack(alignment: .leading, spacing: 10) {
                if app.tonNetwork.usdtAvailable {
                    HStack(alignment: .firstTextBaseline) {
                        Text("USDT").font(.headline)
                        Spacer()
                        VStack(alignment: .trailing, spacing: 2) {
                            Text(TokenAmount.format(BigUInt(app.tonBalancesState?.usdtUnits ?? 0), decimals: 6))
                                .font(.system(size: 26, weight: .bold, design: .rounded))
                                .monospacedDigit()
                            if let fiat = fiatLine(units: app.tonBalancesState?.usdtUnits ?? 0, decimals: 6, symbol: "USDT") {
                                Text(fiat).font(.caption).foregroundStyle(.secondary)
                            }
                        }
                    }
                    Divider()
                }
                HStack {
                    Text("TON (fees)").font(.subheadline).foregroundStyle(.secondary)
                    Spacer()
                    VStack(alignment: .trailing, spacing: 2) {
                        Text(TONService.formatTON(app.tonBalancesState?.nanotons ?? 0) + " TON")
                            .font(.subheadline.monospaced())
                            .foregroundStyle(.secondary)
                        if let fiat = fiatLine(units: app.tonBalancesState?.nanotons ?? 0, decimals: 9, symbol: "TON") {
                            Text(fiat).font(.caption).foregroundStyle(.secondary)
                        }
                    }
                }
                if app.tonBalancesState?.deployed == false, (app.tonBalancesState?.nanotons ?? 0) > 0 {
                    Text("Wallet contract deploys automatically with your first send.")
                        .font(.caption).foregroundStyle(.secondary)
                }
                if let error = app.tonError {
                    Label(error, systemImage: "wifi.exclamationmark")
                        .font(.caption).foregroundStyle(.orange)
                }
            }
            .padding(14)
            .background(.quaternary.opacity(0.4))
            .clipShape(RoundedRectangle(cornerRadius: 10))

            HStack(spacing: 12) {
                Button {
                    mode = .send
                } label: {
                    Label("Send", systemImage: "arrow.up.circle.fill").frame(maxWidth: .infinity)
                }
                .buttonStyle(.borderedProminent)
                Button {
                    mode = .receive
                } label: {
                    Label("Receive", systemImage: "arrow.down.circle").frame(maxWidth: .infinity)
                }
                Button {
                    Task { await app.refreshTON() }
                } label: {
                    Image(systemName: "arrow.clockwise")
                }
                .help("Refresh")
            }

            Text("ed25519 (wallet v4R2) from your existing recovery phrase — note: Tonkeeper's default import expects TON-native 24-word phrases, not BIP-39. USDT is a jetton: sends attach ~0.07 TON for fees, the unused part is refunded.")
                .font(.caption)
                .foregroundStyle(.secondary)

            Picker("Network", selection: Binding(
                get: { app.tonNetwork },
                set: { newValue in Task { await app.switchTONNetwork(to: newValue) } }
            )) {
                ForEach(TONService.TONNetwork.allCases, id: \.self) { network in
                    Text(network.displayName).tag(network)
                }
            }
            .pickerStyle(.segmented)
        }
    }

    private func fiatLine(units: UInt64, decimals: Int, symbol: String) -> String? {
        guard app.pricesEnabled, units > 0, let price = app.fiatPrices[symbol] else { return nil }
        let value = PriceService.fiatValue(units: BigUInt(units), decimals: decimals, price: price)
        return "≈ " + PriceService.formatFiat(value, currency: app.fiatCurrency)
    }

    // MARK: - Receive

    private var receive: some View {
        VStack(spacing: 14) {
            if let address = app.tonAddress {
                if let qr = QRCode.image(for: address) {
                    Image(nsImage: qr)
                        .interpolation(.none)
                        .resizable()
                        .frame(width: 200, height: 200)
                        .background(.white)
                        .clipShape(RoundedRectangle(cornerRadius: 8))
                }
                Text(address)
                    .font(.callout.monospaced())
                    .textSelection(.enabled)
                    .padding(8)
                    .background(.quaternary.opacity(0.4))
                    .clipShape(RoundedRectangle(cornerRadius: 8))
                CopyButton(text: address)
                Text("One address for TON and every jetton on \(app.tonNetwork.displayName).")
                    .font(.caption).foregroundStyle(.secondary)
            }
            Button("Back") { mode = .overview }
        }
        .frame(maxWidth: .infinity)
    }

    // MARK: - Send

    private var send: some View {
        VStack(alignment: .leading, spacing: 12) {
            if let ref = sentRef {
                sentView(ref)
            } else if let prepared {
                confirmView(prepared)
            } else {
                sendForm
            }
        }
    }

    private var sendForm: some View {
        VStack(alignment: .leading, spacing: 12) {
            if app.tonNetwork.usdtAvailable {
                Picker("Asset", selection: $sendUSDT) {
                    Text("TON").tag(false)
                    Text("USDT").tag(true)
                }
                .pickerStyle(.segmented)
            }
            TextField("Recipient (UQ… / EQ…)", text: $recipient)
                .textFieldStyle(.roundedBorder)
                .font(.body.monospaced())
                .autocorrectionDisabled()
            if !recipient.isEmpty && !TONService.validate(address: recipient) {
                Label("Not a valid TON address", systemImage: "xmark.circle")
                    .font(.caption).foregroundStyle(.red)
            }
            HStack {
                TextField("Amount", text: $amountInput)
                    .textFieldStyle(.roundedBorder)
                    .font(.body.monospaced())
                Text(sendUSDT ? "USDT" : "TON").foregroundStyle(.secondary)
            }
            Text(sendUSDT
                 ? "Balance: \(TokenAmount.format(BigUInt(app.tonBalancesState?.usdtUnits ?? 0), decimals: 6)) USDT"
                 : "Balance: \(TONService.formatTON(app.tonBalancesState?.nanotons ?? 0)) TON")
                .font(.caption).foregroundStyle(.secondary)
            if let errorMessage {
                Text(errorMessage).foregroundStyle(.red).font(.callout)
            }
            HStack {
                Button("Back") { mode = .overview; errorMessage = nil }
                Spacer()
                if busy { ProgressView().controlSize(.small) }
                Button("Review") { estimate() }
                    .buttonStyle(.borderedProminent)
                    .disabled(!formValid || busy)
            }
        }
    }

    private var parsedAmount: UInt64? {
        sendUSDT ? TONService.parseUSDT(amountInput) : TONService.parseTON(amountInput)
    }

    private var formValid: Bool {
        TONService.validate(address: recipient) && (parsedAmount ?? 0) > 0
    }

    private func estimate() {
        guard let amount = parsedAmount else { return }
        errorMessage = nil
        busy = true
        let to = recipient.trimmingCharacters(in: .whitespacesAndNewlines)
        let usdt = sendUSDT
        Task {
            do {
                prepared = try await app.tonService.estimateSend(
                    to: to, amountUnits: amount, isUSDT: usdt)
            } catch {
                errorMessage = error.localizedDescription
            }
            busy = false
        }
    }

    private func confirmView(_ p: TONService.PreparedTONSend) -> some View {
        VStack(alignment: .leading, spacing: 12) {
            Text("Confirm transaction").font(.headline)
            Grid(alignment: .leading, horizontalSpacing: 16, verticalSpacing: 8) {
                GridRow {
                    Text("Recipient").foregroundStyle(.secondary)
                    Text(p.recipient).font(.callout.monospaced())
                        .textSelection(.enabled)
                        .lineLimit(1).truncationMode(.middle)
                }
                GridRow {
                    Text("Amount").foregroundStyle(.secondary)
                    Text(p.isUSDT
                         ? "\(TokenAmount.format(BigUInt(p.amountUnits), decimals: 6)) USDT"
                         : "\(TONService.formatTON(p.amountUnits)) TON")
                        .fontWeight(.semibold)
                }
                GridRow {
                    Text("Network").foregroundStyle(.secondary)
                    Text(p.network.displayName)
                }
                GridRow {
                    Text("Est. fee").foregroundStyle(.secondary)
                    Text("≈ \(TONService.formatTON(p.estimatedFeeNanotons)) TON" + (p.isUSDT ? " (excess refunded)" : ""))
                }
            }
            .font(.callout)
            Divider()
            SecureField("Vault password to sign", text: $password)
                .textFieldStyle(.roundedBorder)
            if let errorMessage {
                Text(errorMessage).foregroundStyle(.red).font(.callout)
            }
            HStack {
                Button("Back") {
                    prepared = nil
                    password = ""
                }
                Spacer()
                if busy { ProgressView().controlSize(.small) }
                Button("Sign & send") { broadcast(p) }
                    .buttonStyle(.borderedProminent)
                    .disabled(password.isEmpty || busy)
            }
        }
    }

    private func broadcast(_ p: TONService.PreparedTONSend) {
        busy = true
        errorMessage = nil
        let candidate = password
        let manager = app.keyManager
        Task {
            do {
                let mnemonic = try await Task.detached {
                    try manager.unlock(password: candidate).mnemonic
                }.value
                let ref = try await app.tonService.send(p, mnemonic: mnemonic)
                password = ""
                sentRef = ref
                await app.refreshTON()
            } catch {
                errorMessage = error.localizedDescription
            }
            busy = false
        }
    }

    private func sentView(_ ref: String) -> some View {
        VStack(spacing: 12) {
            Image(systemName: "paperplane.circle.fill")
                .font(.system(size: 38)).foregroundStyle(.green)
            Text("Transaction sent").font(.headline)
            Text("It will appear on the explorer within seconds.")
                .font(.callout).foregroundStyle(.secondary)
            if let address = app.tonAddress {
                Link("View account on Tonviewer", destination: app.tonNetwork.explorerAddressURL(address))
            }
            Button("Done") {
                sentRef = nil
                prepared = nil
                recipient = ""
                amountInput = ""
                mode = .overview
            }
            .buttonStyle(.borderedProminent)
        }
        .frame(maxWidth: .infinity)
    }
}

extension TONService.TONNetwork {
    var usdtAvailable: Bool { usdtMaster != nil }
}