//
//  AdminFeedbackShotsView.swift
//  FTStore Admin
//
//  The screenshots on a report or a reply, and what can be done about them.
//
//  A bug report is very often a picture, so this is frequently the most useful
//  thing on the screen. It sits with the text rather than behind a disclosure,
//  and tapping one opens it full size, because the detail that matters is
//  usually small.
//
//  Two actions, and the difference between them is the whole point. Hiding is
//  reversible: the row and the file stay, the picture stops being served to the
//  board, and whoever uploaded it still sees it marked as removed. Deleting is
//  admin-only, takes the bytes off the disk, and has no undo.
//
//  Hiding deliberately frees nothing, so the size stays on screen either way —
//  a takedown that quietly stopped counting would make the storage figure a
//  story about what is visible rather than about what is stored.
//

import SwiftUI

struct AdminFeedbackShotsView: View {
	@EnvironmentObject private var session: AdminSession

	let shots: [AdminFeedbackAttachment]
	/// Reload the thread, so a hide or a delete is reflected rather than assumed.
	let onChanged: () async -> Void
	/// Where a failure goes. The thread already has one banner; a second place
	/// for errors on the same screen would be a second place to look.
	@Binding var banner: String?

	@State private var _busyId: Int?
	@State private var _viewing: AdminFeedbackAttachment?
	@State private var _deleting: AdminFeedbackAttachment?

	private static let _height: CGFloat = 110

	var body: some View {
		if !shots.isEmpty {
			ScrollView(.horizontal, showsIndicators: false) {
				HStack(alignment: .top, spacing: 10) {
					ForEach(shots) { shot in
						_tile(shot)
					}
				}
				.padding(.vertical, 2)
			}
			.fullScreenCover(item: $_viewing) { shot in
				AdminShotViewer(shot: shot)
			}
			.alert(item: $_deleting) { shot in
				Alert(
					title: Text("Delete this picture?"),
					message: Text("The file goes off the disk and there is no undo. To take it off the board reversibly, hide it instead."),
					primaryButton: .destructive(Text("Delete")) { _delete(shot) },
					secondaryButton: .cancel()
				)
			}
		}
	}

	@ViewBuilder
	private func _tile(_ shot: AdminFeedbackAttachment) -> some View {
		VStack(alignment: .leading, spacing: 4) {
			Button {
				_viewing = shot
			} label: {
				AsyncImage(url: AdminAPI.mediaURL(shot.url)) { phase in
					switch phase {
					case .success(let image):
						image.resizable().scaledToFill()
					case .failure:
						// Worth saying rather than showing a grey rectangle that
						// looks like it is still trying.
						Image(systemName: "exclamationmark.triangle")
							.foregroundStyle(.secondary)
					default:
						ProgressView()
					}
				}
				.frame(
					width: Self._height * shot.aspectRatio,
					height: Self._height
				)
				.background(Color(uiColor: .tertiarySystemFill))
				.clipShape(RoundedRectangle(cornerRadius: 10, style: .continuous))
				.opacity(shot.hidden ? 0.45 : 1)
			}
			.buttonStyle(.plain)

			HStack(spacing: 6) {
				Text(AdminFormat.bytes(Int64(shot.bytes)))
					.font(.caption2)
					.foregroundStyle(.secondary)

				if shot.hidden {
					Text("Hidden")
						.font(.caption2.weight(.semibold))
						.foregroundStyle(.orange)
				}

				Spacer(minLength: 0)

				if _busyId == shot.id {
					ProgressView().controlSize(.mini)
				} else {
					Button {
						_setHidden(shot, to: !shot.hidden)
					} label: {
						Image(systemName: shot.hidden ? "eye" : "eye.slash")
							.font(.caption)
					}
					.buttonStyle(.plain)
					.foregroundStyle(shot.hidden ? .green : .orange)

					if session.isAdmin {
						Button {
							_deleting = shot
						} label: {
							Image(systemName: "trash")
								.font(.caption)
						}
						.buttonStyle(.plain)
						.foregroundStyle(.red)
					}
				}
			}
			.frame(width: Self._height * shot.aspectRatio)
		}
	}

	// MARK: Actions

	private func _setHidden(_ shot: AdminFeedbackAttachment, to hidden: Bool) {
		_run(shot) {
			_ = try await session.act(
				.put,
				"/api/feedback/attachments/\(shot.id)",
				body: AdminRequest.FeedbackAttachmentModeration(hidden: hidden)
			)
		}
	}

	private func _delete(_ shot: AdminFeedbackAttachment) {
		_run(shot) {
			_ = try await session.act(.delete, "/api/feedback/attachments/\(shot.id)")
		}
	}

	private func _run(
		_ shot: AdminFeedbackAttachment,
		_ operation: @escaping @MainActor () async throws -> Void
	) {
		_busyId = shot.id
		Task { @MainActor in
			do {
				try await operation()
			} catch {
				banner = (error as? LocalizedError)?.errorDescription
					?? error.localizedDescription
			}
			_busyId = nil
			await onChanged()
		}
	}
}

// MARK: - Viewer

/// One screenshot, as large as the screen will make it.
///
/// Pinch to zoom, because the reason a screenshot was attached is often a detail
/// in a corner of it. `MagnificationGesture` rather than the iOS 17
/// `MagnifyGesture`, matching the rest of the codebase's deployment target.
struct AdminShotViewer: View {
	@Environment(\.dismiss) private var dismiss

	let shot: AdminFeedbackAttachment

	@State private var _zoom: CGFloat = 1
	@State private var _committedZoom: CGFloat = 1

	var body: some View {
		ZStack {
			Color.black.ignoresSafeArea()

			AsyncImage(url: AdminAPI.mediaURL(shot.url)) { phase in
				switch phase {
				case .success(let image):
					image
						.resizable()
						.scaledToFit()
						.scaleEffect(_zoom)
						.gesture(
							MagnificationGesture()
								.onChanged { scale in
									_zoom = max(1, _committedZoom * scale)
								}
								.onEnded { _ in _committedZoom = _zoom }
						)
				case .failure:
					Label("That picture couldn't be loaded.", systemImage: "exclamationmark.triangle")
						.foregroundStyle(.white)
				default:
					ProgressView().tint(.white)
				}
			}
		}
		.overlay(alignment: .topTrailing) {
			Button {
				dismiss()
			} label: {
				Image(systemName: "xmark")
					.font(.headline)
					.foregroundStyle(.white)
					.padding(12)
					.background(.ultraThinMaterial, in: Circle())
			}
			.padding()
		}
		.statusBarHidden()
	}
}