//
//  AdminBlocklistView.swift
//  FTStore Admin
//
//  Tweak names this server will not take. Mirrors the panel on /admin/settings.
//
//  A rule is a name plus a scope, and an empty scope means everywhere — which
//  is the common case, so it is what happens when the field is left alone
//  rather than something to switch on.
//
//  The note is not decoration. Matching folds case and punctuation and looks
//  anywhere in the name, which is broad on purpose; months later the only way
//  to tell a deliberate rule from an over-eager one is to have written down
//  why.
//
//  Saved on its own, immediately, like everything else in this app — there is
//  no Save button here either.
//

import SwiftUI

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

	@StateObject private var _settings = AdminLoader<AdminSettingsResponse>()

	@State private var _entries: [AdminBlockedTweak] = []
	@State private var _busy = false
	@State private var _banner: String?

	@State private var _adding = false
	@State private var _newName = ""
	@State private var _newSource = ""
	@State private var _newNote = ""

	var body: some View {
		List {
			if let banner = _banner {
				Section {
					Text(banner).font(.footnote).foregroundStyle(.secondary)
				}
			}

			Section {
				if _settings.isLoading && !_settings.hasLoaded {
					AdminLoadingRow()
				} else if let error = _settings.errorMessage, !_settings.hasLoaded {
					AdminErrorRow(message: error) { Task { await _reload() } }
				} else if _entries.isEmpty {
					AdminEmptyRow(
						icon: "hand.raised",
						title: "Nothing is blocked",
						detail: "Everything a source publishes is considered."
					)
				} else {
					ForEach(_entries) { entry in
						_row(entry)
							.swipeActions(edge: .trailing) {
								Button(role: .destructive) {
									_remove(entry)
								} label: {
									Label("Remove", systemImage: "trash")
								}
							}
					}
				}
			} header: {
				Text("Blocked")
			} footer: {
				Text("Builds whose name matches are never taken. Checked on the file name before downloading and on the app's real name after, so a build named nothing like its contents is still caught. Case and punctuation are ignored and the match is anywhere in the name.")
			}
		}
		.navigationTitle("Blocked Tweaks")
		.navigationBarTitleDisplayMode(.inline)
		.refreshable { await _reload() }
		.task { await _reload() }
		.disabled(_busy)
		.toolbar {
			ToolbarItem(placement: .topBarTrailing) {
				if _busy {
					ProgressView()
				} else {
					Button {
						_newName = ""
						_newSource = ""
						_newNote = ""
						_adding = true
					} label: {
						Image(systemName: "plus")
					}
				}
			}
		}
		.alert("Block a name", isPresented: $_adding) {
			TextField("Tweak or app name", text: $_newName)
				.textInputAutocapitalization(.never)
				.autocorrectionDisabled()
			TextField("Source, or empty for everywhere", text: $_newSource)
				.textInputAutocapitalization(.never)
				.autocorrectionDisabled()
			TextField("Why (optional)", text: $_newNote)
			Button("Block") { _add() }
			Button("Cancel", role: .cancel) {}
		} message: {
			Text("Leave the source empty to block the name everywhere. Write @channel or github:owner/repo to block it from one source only.")
		}
	}

	@ViewBuilder
	private func _row(_ entry: AdminBlockedTweak) -> some View {
		VStack(alignment: .leading, spacing: 4) {
			HStack(spacing: 6) {
				Text(entry.name)
					.font(.subheadline.weight(.medium))
					.lineLimit(1)

				// The scope, always stated. A rule whose reach is not on screen
				// is one somebody will misread as global.
				Label {
					Text(entry.sourceId ?? .localized("everywhere"))
				} icon: {
					Image(systemName: entry.sourceId == nil ? "globe" : "antenna.radiowaves.left.and.right")
				}
				.font(.caption2)
				.padding(.horizontal, 6)
				.padding(.vertical, 2)
				.background(Color(uiColor: .tertiarySystemFill), in: Capsule())
				.foregroundStyle(.secondary)
			}

			if let note = entry.note, !note.isEmpty {
				Text(note)
					.font(.caption)
					.foregroundStyle(.secondary)
			}
		}
		.padding(.vertical, 2)
	}

	// MARK: Actions

	private func _reload() async {
		await _settings.load {
			try await session.get("/api/settings", as: AdminSettingsResponse.self)
		}
		if let list = _settings.value?.data.blockedTweaks {
			_entries = list
		}
	}

	private func _add() {
		let name = _newName.trimmingCharacters(in: .whitespaces)
		guard !name.isEmpty else { return }

		let entry = AdminBlockedTweak(
			name: name,
			sourceId: _newSource.trimmingCharacters(in: .whitespaces).nilIfEmpty,
			note: _newNote.trimmingCharacters(in: .whitespaces).nilIfEmpty
		)
		_save(_entries + [entry], .localized("\"%@\" is blocked.", name))
	}

	private func _remove(_ entry: AdminBlockedTweak) {
		_save(_entries.filter { $0.id != entry.id }, .localized("Rule removed."))
	}

	private func _save(_ next: [AdminBlockedTweak], _ fallback: String) {
		_busy = true
		Task { @MainActor in
			do {
				let ack = try await session.act(
					.put,
					"/api/settings",
					body: AdminRequest.Blocklist(blocked_tweaks: next)
				)
				_banner = ack.message ?? fallback
			} catch {
				_banner = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
			}
			_busy = false
			await _reload()
		}
	}
}

private extension String {
	/// An empty scope means "everywhere", and the server reads that as null.
	var nilIfEmpty: String? { isEmpty ? nil : self }
}