// The gamepad-driven presentation of the game library (iOS/iPadOS only — see LibraryView's
// `gamepadUIActive` branch): a classic coverflow instead of the touch grid. All the
// scrolling/snapping/navigation/haptics live in GamepadCarousel; this file is the coverflow card
// (poster + the 3D recede treatment via `.scrollTransition`), the "now focused" detail panel, and
// the controller-glyph hints. A steps through covers, A launches the centered title, B closes, and
// the shoulders (L1/R1) jump a handful at a time through a long library.
//
// Layout discipline (so nothing is EVER clipped, portrait or landscape): the gradient is a
// `.background` modifier — NOT a ZStack sibling — because an `.ignoresSafeArea()` sibling expands the
// stack to full-screen and hands the GeometryReader the full height, laying content out under the
// status bar / home indicator. As a background it draws behind without affecting layout, so the
// GeometryReader is sized to the safe area, and the controller-glyph hints are pinned inside it with
// `.safeAreaInset(.bottom, alignment: .leading)`. Cover size is then derived from the height that
// remains, so a tall 2:3 poster + the detail line always fit.

import PunktfunkKit
import SwiftUI
#if os(iOS)
import GameController
import UIKit

struct LibraryCoverflowView: View {
    let games: [GameEntry]
    let imageSession: URLSession?
    var onLaunch: ((String) -> Void)?
    /// Button B (back) — dismisses the library screen. No touch equivalent needed here (the toolbar
    /// Close button already covers that); this is what makes gamepad-only exit possible.
    var onDismiss: (() -> Void)?

    /// `.compact` in a landscape phone window — drives a tighter poster so everything still fits.
    @Environment(\.verticalSizeClass) private var vSizeClass
    @State private var selection: String?

    private var compact: Bool { vSizeClass == .compact }

    var body: some View {
        GeometryReader { geo in
            content(for: geo.size)
        }
        .safeAreaInset(edge: .bottom, alignment: .leading, spacing: 0) {
            hintBar
                .padding(.leading, 22)
                .padding(.vertical, compact ? 6 : 10)
        }
        .background {
            LinearGradient(
                colors: [.black, Color.brand.opacity(0.16), .black],
                startPoint: .top, endPoint: .bottom)
                .ignoresSafeArea()
        }
    }

    @ViewBuilder private func content(for size: CGSize) -> some View {
        // Fit the tallest poster into the height the detail line + paddings leave (the hints are a
        // safe-area inset, already out of this budget) — capped so it never dwarfs a large iPad and
        // clamped by width on a narrow screen.
        let reserved: CGFloat = compact ? 72 : 96 // detail line + spacers
        let coverHeight = min(360, min(max(140, size.height - reserved), size.width * 0.9))
        let coverWidth = coverHeight * 2 / 3

        VStack(spacing: 0) {
            Spacer(minLength: 4)
            carousel(coverWidth: coverWidth, coverHeight: coverHeight)
            detailPanel
                .padding(.top, 12)
            Spacer(minLength: 4)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }

    private func carousel(coverWidth: CGFloat, coverHeight: CGFloat) -> some View {
        GamepadCarousel(
            items: games,
            selection: $selection,
            itemWidth: coverWidth,
            spacing: 34,
            onActivate: { onLaunch?($0.id) },
            onBack: { onDismiss?() },
            shoulderJump: 5
        ) { game in
            cover(game, width: coverWidth, height: coverHeight)
        }
        .frame(height: coverHeight + 44)
    }

    /// One cover + the coverflow recede. Every continuous visual reads the scroll view's own
    /// per-frame `phase` (real distance-from-centered), so the tilt tracks what's actually on screen
    /// mid-scroll. `.shadow` isn't a `VisualEffect`, so it's baked constant into the card; the
    /// scale/rotation/opacity ramp already makes the centered cover prominent.
    private func cover(_ game: GameEntry, width: CGFloat, height: CGFloat) -> some View {
        PosterImage(candidates: game.art.posterCandidates, title: game.title, session: imageSession)
            .frame(width: width, height: height)
            .clipShape(RoundedRectangle(cornerRadius: 16, style: .continuous))
            .overlay(alignment: .topLeading) { StoreBadge(isCustom: game.isCustom) }
            .overlay {
                RoundedRectangle(cornerRadius: 16, style: .continuous)
                    .strokeBorder(.white.opacity(0.12), lineWidth: 1)
            }
            .shadow(color: .black.opacity(0.5), radius: 16, y: 12)
            .scrollTransition { content, phase in
                let v = phase.value
                let d = CGFloat(min(abs(v), 1))
                let scale = 1 - d * 0.24
                let rot = v * -38
                let anchor: UnitPoint = v < 0 ? .trailing : .leading
                let bright = Double(-d * 0.22)
                let fade = Double(1 - d * 0.38)
                return content
                    .scaleEffect(scale)
                    .rotation3DEffect(
                        .degrees(rot), axis: (x: 0, y: 1, z: 0), anchor: anchor, perspective: 0.55)
                    .brightness(bright)
                    .opacity(fade)
            }
    }

    /// The centered title + store tag — empty (not hidden) so the layout doesn't jump.
    @ViewBuilder private var detailPanel: some View {
        let game = games.first { $0.id == selection }
        VStack(spacing: 6) {
            Text(game?.title ?? " ")
                .font(.geist(compact ? 22 : 25, .bold, relativeTo: .title))
                .foregroundStyle(.white)
                .lineLimit(1)
                .minimumScaleFactor(0.75)
                .multilineTextAlignment(.center)
            if let game {
                Text(game.isCustom ? "CUSTOM" : "STEAM")
                    .font(.geist(11, .semibold, relativeTo: .caption2))
                    .tracking(1.2)
                    .foregroundStyle(.white.opacity(0.5))
            }
        }
        .frame(maxWidth: .infinity)
        .padding(.horizontal, 24)
        .animation(.smooth(duration: 0.25), value: selection)
    }

    // MARK: - Hint bar (pinned bottom-leading via safeAreaInset)

    private var hintBar: some View {
        HStack(spacing: 18) {
            if onLaunch != nil {
                hint(glyph: buttonGlyph(\.buttonA, fallback: "a.circle"), text: "Launch")
            }
            hint(glyph: buttonGlyph(\.buttonB, fallback: "b.circle"), text: "Close")
        }
        .font(.geist(14, .semibold, relativeTo: .subheadline))
        .foregroundStyle(.white.opacity(0.85))
    }

    private func hint(glyph: String, text: String) -> some View {
        HStack(spacing: 7) {
            Image(systemName: glyph)
                .font(.system(size: 19))
                .foregroundStyle(.white)
            Text(text)
        }
        .fixedSize() // keep glyph + label together; never truncate a hint mid-word
    }

    /// The active controller's real glyph for a button (Xbox "B", DualSense ◯, …) via
    /// `sfSymbolsName`; a generic fallback before a controller profile resolves.
    private func buttonGlyph(
        _ button: KeyPath<GCExtendedGamepad, GCControllerButtonInput>, fallback: String
    ) -> String {
        GamepadManager.shared.active?.controller.extendedGamepad?[keyPath: button].sfSymbolsName
            ?? fallback
    }
}
#endif