import SessionCore
import SwiftTerm
import SwiftUI
import UIKit

/// T-iOS-11 · The terminal screen: SwiftTerm view + key bar + status banner.
///
/// Data flow (byte-shuttle preserved end to end):
/// - inbound: `SessionEvent.output` → `TerminalViewModel` sink → `feed(text:)`
///   (opaque ANSI/UTF-8 — the app NEVER parses terminal semantics);
/// - outbound: SwiftTerm delegate `send` → `viewModel.sendInput`,
///   `sizeChanged` → `viewModel.sendResize`; KeyBar taps and hardware
///   `UIKeyCommand`s go through `viewModel.send(key:)` — every label→bytes
///   lookup via `KeyByteMap`, bypassing SwiftTerm's text path so the soft
///   keyboard never pops (mirrors the web bar's ws.send bypass).
/// - IME: NO custom keydown/composition interception — SwiftTerm manages
///   composition itself (CLAUDE.md gotcha; plan §7 T-iOS-11).
///
/// Navigation/lifecycle wiring (engine open/close, scenePhase) lands in
/// T-iOS-15 — this screen only renders and routes.
struct TerminalScreen: View {
    let viewModel: TerminalViewModel

    private enum Metrics {
        static let bannerHorizontalPadding: CGFloat = 12
        static let bannerTopPadding: CGFloat = 8
    }

    var body: some View {
        TerminalHostView(viewModel: viewModel)
            .ignoresSafeArea(.container, edges: .bottom)
            .overlay(alignment: .top) {
                if let model = viewModel.bannerModel {
                    ReconnectBanner(model: model)
                        .padding(.horizontal, Metrics.bannerHorizontalPadding)
                        .padding(.top, Metrics.bannerTopPadding)
                        .transition(.move(edge: .top).combined(with: .opacity))
                }
            }
            .animation(.default, value: viewModel.bannerModel)
            .onAppear { viewModel.start() }
    }
}

// MARK: - SwiftTerm bridge

/// `UIViewRepresentable` around `SwiftTerm.TerminalView` (plan §3.5). The
/// KeyBar is installed as `inputAccessoryView`; hardware chords come from the
/// `KeyCommandTerminalView` subclass. Both route through the ViewModel.
private struct TerminalHostView: UIViewRepresentable {
    let viewModel: TerminalViewModel

    func makeCoordinator() -> Coordinator {
        Coordinator(viewModel: viewModel)
    }

    func makeUIView(context: Context) -> KeyCommandTerminalView {
        let terminal = KeyCommandTerminalView(frame: .zero)
        terminal.terminalDelegate = context.coordinator

        let viewModel = viewModel
        terminal.onKeyCommand = { key in viewModel.send(key: key) }

        let keyBar = KeyBarView()
        keyBar.onKey = { key in viewModel.send(key: key) }
        terminal.inputAccessoryView = keyBar

        // Output sink: buffered replay flushes now, live bytes follow.
        // @MainActor-typed closure — feeding off the main actor cannot compile.
        viewModel.attachTerminalSink { [weak terminal] text in
            terminal?.feed(text: text)
        }
        return terminal
    }

    func updateUIView(_ uiView: KeyCommandTerminalView, context: Context) {
        // State-driven UI lives in SwiftUI (banner overlay); the terminal view
        // itself is driven by the sink/delegate, nothing to push here.
    }

    /// SwiftTerm's delegate is a pre-concurrency protocol; the conformance is
    /// `@preconcurrency` — SwiftTerm only calls it from the main thread (the
    /// view itself is `@MainActor`), which the runtime check enforces.
    @MainActor
    final class Coordinator: NSObject, @preconcurrency TerminalViewDelegate {
        private let viewModel: TerminalViewModel

        init(viewModel: TerminalViewModel) {
            self.viewModel = viewModel
        }

        /// User typed into SwiftTerm (soft/hardware keyboard, IME result):
        /// raw bytes, passed through verbatim (invariant #9).
        func send(source: TerminalView, data: ArraySlice<UInt8>) {
            viewModel.sendInput(String(decoding: data, as: UTF8.self))
        }

        /// Layout produced a new grid → server `resize` (SIGWINCH). This is
        /// also the latest-writer-wins size claim (v0.4 sizing model).
        func sizeChanged(source: TerminalView, newCols: Int, newRows: Int) {
            guard newCols > 0, newRows > 0 else { return } // pre-layout noise
            viewModel.sendResize(cols: newCols, rows: newRows)
        }

        /// Tapped link (OSC 8 / detected URL — mirrors web M2 WebLinksAddon).
        /// The link string is untrusted terminal output: http(s) only.
        func requestOpenLink(source: TerminalView, link: String, params: [String: String]) {
            guard let url = URL(string: link),
                  let scheme = url.scheme?.lowercased(),
                  scheme == "http" || scheme == "https"
            else { return }
            UIApplication.shared.open(url)
        }

        // Title/cwd surface in the session list via the server (T-iOS-13/23),
        // not from the local emulator — deliberate no-ops.
        func setTerminalTitle(source: TerminalView, title: String) {}
        func hostCurrentDirectoryUpdate(source: TerminalView, directory: String?) {}
        func scrolled(source: TerminalView, position: Double) {}
        func rangeChanged(source: TerminalView, startY: Int, endY: Int) {}

        /// OSC 52 lets the HOST write the device clipboard silently — declined
        /// (server output is untrusted input; plan §4).
        func clipboardCopy(source: TerminalView, content: Data) {}
    }
}

/// `TerminalView` subclass adding hardware-keyboard `UIKeyCommand`s with the
/// SAME `KeyByteMap` mapping as the key bar (scope decision documented on
/// `HardwareKeyCommands`). Everything else — rendering, selection, IME —
/// is stock SwiftTerm.
final class KeyCommandTerminalView: TerminalView {
    /// Chord outlet; the screen routes it to `TerminalViewModel.send(key:)`.
    var onKeyCommand: (@MainActor (KeyByteMap.Key) -> Void)?

    override var keyCommands: [UIKeyCommand]? {
        (super.keyCommands ?? [])
            + HardwareKeyCommands.build(action: #selector(runHardwareKeyCommand(_:)))
    }

    @objc private func runHardwareKeyCommand(_ sender: UIKeyCommand) {
        guard let key = HardwareKeyCommands.key(matching: sender) else { return }
        onKeyCommand?(key)
    }
}