import SessionCore
import SwiftUI

/// Copy + wire pairing for one gate button — the SINGLE label source for both
/// gate surfaces (`GateBanner`, `PlanGateSheet`). Labels mirror
/// public/tabs.ts:334-350 byte-for-byte; the affordance→ClientMessage mapping
/// itself is frozen in SessionCore (`GateState.Affordance.clientMessage`).
struct GateChoiceSpec: Equatable {
    let label: String
    let affordance: GateState.Affordance

    /// Ordered button set for `gate` (tool → two, plan → three), driven by the
    /// frozen `GateState.affordances` list.
    static func specs(for gate: GateState) -> [GateChoiceSpec] {
        gate.affordances.map { GateChoiceSpec(label: label(for: $0), affordance: $0) }
    }

    static func label(for affordance: GateState.Affordance) -> String {
        switch affordance {
        case .approveAuto: return "✓ Approve + Auto"
        case .approveReview: return "✓ Approve + Review"
        case .keepPlanning: return "✎ Keep Planning"
        case .approve: return "✓ Approve"
        case .reject: return "✗ Reject"
        }
    }
}

/// T-iOS-14 · Two-button banner for an ordinary TOOL gate (plan gates get the
/// three-way `PlanGateSheet`). Render-only: state lives in `GateViewModel`.
/// Every tap reports the affordance PLUS the epoch of the gate THIS banner
/// rendered — the VM drops stale taps (first-line guard); wiring into
/// TerminalScreen is T-iOS-15.
struct GateBanner: View {
    let gate: GateState
    let onDecide: (GateState.Affordance, Int) -> Void

    private enum Metrics {
        static let spacing: CGFloat = 8
        static let horizontalPadding: CGFloat = 14
        static let verticalPadding: CGFloat = 10
        static let cornerRadius: CGFloat = 12
        static let messageLineLimit = 2
    }

    /// Banner headline, mirror of public/tabs.ts:329:
    /// `Claude wants to use ${pendingTool ?? 'a tool'}`. `detail` is
    /// server-supplied display text (untrusted) — rendered as plain Text only.
    static func message(for gate: GateState) -> String {
        "Claude wants to use \(gate.detail ?? "a tool")"
    }

    var body: some View {
        VStack(alignment: .leading, spacing: Metrics.spacing) {
            Text(Self.message(for: gate))
                .font(.footnote.weight(.semibold))
                .lineLimit(Metrics.messageLineLimit)
            HStack(spacing: Metrics.spacing) {
                ForEach(GateChoiceSpec.specs(for: gate), id: \.affordance) { spec in
                    decisionButton(spec)
                }
            }
        }
        .padding(.horizontal, Metrics.horizontalPadding)
        .padding(.vertical, Metrics.verticalPadding)
        .background(.thinMaterial, in: RoundedRectangle(cornerRadius: Metrics.cornerRadius))
        .accessibilityElement(children: .contain)
    }

    private func decisionButton(_ spec: GateChoiceSpec) -> some View {
        Button(spec.label) {
            onDecide(spec.affordance, gate.epoch) // epoch of the RENDERED gate
        }
        .accessibilityIdentifier("gate.decision.\(spec.affordance)")
        .buttonStyle(.borderedProminent)
        .controlSize(.small)
        .tint(tint(for: spec.affordance))
    }

    private func tint(for affordance: GateState.Affordance) -> Color {
        switch affordance {
        case .approve, .approveAuto, .approveReview: return .green
        case .reject: return .red
        case .keepPlanning: return .indigo
        }
    }
}