import Foundation
import Testing

@testable import phbar

// MARK: - Fake event source

/// A no-op source that records its lifecycle and can be fired on demand.
@MainActor
private final class FakeEventSource: PHEventSource {
	private(set) var startCount = 0
	private(set) var stopCount = 0
	private var notify: (@MainActor @Sendable () -> Void)?

	func start(notify: @escaping @MainActor @Sendable () -> Void) {
		startCount += 1
		self.notify = notify
	}

	func stop() {
		stopCount += 1
		notify = nil
	}

	func fire() { notify?() }
}

// MARK: - Event decoding

@MainActor
@Test func eventDecodesFromKnownStrings() throws {
	let toml = """
	[[block]]
	command = "echo hi"
	events = ["volume", "network", "appearance", "power", "mpd"]
	"""

	let blocks = try PHBlock.load(from: toml)

	#expect(blocks[0].events == [PHEvent("volume"), PHEvent("network"), PHEvent("appearance"), PHEvent("power"), PHEvent("mpd")])
}

@MainActor
@Test func eventAcceptsArbitraryStringAsCustom() throws {
	// Unknown strings become custom event names resolved at runtime against
	// `<config>/events/<name>/`.
	let blocks = try PHBlock.load(from: """
	[[block]]
	command = "echo hi"
	events = ["totally_made_up"]
	""")

	#expect(blocks[0].events == [PHEvent("totally_made_up")])
}

@MainActor
@Test func eventsOptionalWhenOmitted() throws {
	let blocks = try PHBlock.load(from: """
	[[block]]
	command = "echo hi"
	""")

	#expect(blocks[0].events == nil)
}

// MARK: - Event loader

@MainActor
@Test func defaultFactoryReturnsNilWithoutRecognizer() {
	// No recognizer installed at a clean directory → factory yields nil.
	let loader = PHEventLoader(directory: FileManager.default.temporaryDirectory)
	let factory: @MainActor @Sendable (PHEvent) -> (any PHEventSource)? = { event in
		guard let recognizer = loader.recognizer(for: event.rawValue) else { return nil }
		return PHExternalEventSource(recognizer: recognizer)
	}
	#expect(factory(PHEvent("anything")) == nil)
}

@MainActor
@Test func eventLoaderReturnsNilForMissingEvent() {
	// A clean directory has no event folders, so every name fails to load.
	let loader = PHEventLoader(directory: FileManager.default.temporaryDirectory)
	let recognizer = loader.recognizer(for: "does-not-exist-\(UUID().uuidString)")
	#expect(recognizer == nil)
}

// MARK: - Event registry

@MainActor
@Test func registryActivatesSourceLazilyAndRefcounts() async throws {
	let fake = FakeEventSource()
	let registry = PHEventRegistry(factory: { _ in fake })

	#expect(fake.startCount == 0)
	#expect(fake.stopCount == 0)

	var fired = 0
	let s1 = registry.subscribe(PHEvent("volume")) { fired += 1 }
	#expect(fake.startCount == 1)
	#expect(registry.subscriberCount(for: PHEvent("volume")) == 1)

	// A second subscriber must reuse the already-running source.
	let s2 = registry.subscribe(PHEvent("volume")) { fired += 1 }
	#expect(fake.startCount == 1)
	#expect(registry.subscriberCount(for: PHEvent("volume")) == 2)

	// One firing fans out to both subscribers.
	fake.fire()
	#expect(fired == 2)

	// Cancelling one keeps the source alive for the other.
	s1.cancel()
	try await Task.sleep(for: .milliseconds(20))
	#expect(fake.stopCount == 0)
	#expect(registry.subscriberCount(for: PHEvent("volume")) == 1)

	fake.fire()
	#expect(fired == 3)

	// Cancelling the last subscriber tears the source down.
	s2.cancel()
	try await Task.sleep(for: .milliseconds(20))
	#expect(fake.stopCount == 1)
	#expect(registry.subscriberCount(for: PHEvent("volume")) == 0)
}

@MainActor
@Test func registryStartsSeparateSourcePerEvent() async throws {
	let volumeFake = FakeEventSource()
	let networkFake = FakeEventSource()
	let factory: @MainActor @Sendable (PHEvent) -> (any PHEventSource)? = { event in
		if event == PHEvent("volume") { return volumeFake }
		return networkFake
	}
	let registry = PHEventRegistry(factory: factory)

	let v = registry.subscribe(PHEvent("volume")) {}
	let n = registry.subscribe(PHEvent("network")) {}

	#expect(volumeFake.startCount == 1)
	#expect(networkFake.startCount == 1)
	#expect(registry.subscriberCount(for: PHEvent("volume")) == 1)
	#expect(registry.subscriberCount(for: PHEvent("network")) == 1)

	v.cancel()
	n.cancel()
}

// MARK: - Block + events

@MainActor
@Test func blockRefreshesOnEvent() async throws {
	let counter = FileManager.default.temporaryDirectory
		.appending(path: "phbar_evt_\(UUID().uuidString)")
	defer { try? FileManager.default.removeItem(at: counter) }
	let path = counter.path

	let fake = FakeEventSource()
	let registry = PHEventRegistry(factory: { _ in fake })

	let block = try PHBlock.load(from: """
	[[block]]
	command = "n=$(cat \(path) 2>/dev/null || echo 0); n=$((n+1)); echo $n > \(path); echo $n"
	events = ["volume"]
	""")[0]
	block.registry = registry

	block.startAutoRefresh()
	try await Task.sleep(for: .milliseconds(100))

	#expect(block.label!.trimmingCharacters(in: .whitespacesAndNewlines) == "1")
	#expect(fake.startCount == 1)

	// Firing the event triggers a second refresh.
	fake.fire()
	try await Task.sleep(for: .milliseconds(100))

	#expect(block.label!.trimmingCharacters(in: .whitespacesAndNewlines) == "2")

	// Stopping cancels the subscription and tears the source down.
	block.stopAutoRefresh()
	try await Task.sleep(for: .milliseconds(20))

	#expect(fake.stopCount == 1)
}

@MainActor
@Test func blockCombinesIntervalAndEvents() async throws {
	let counter = FileManager.default.temporaryDirectory
		.appending(path: "phbar_combo_\(UUID().uuidString)")
	defer { try? FileManager.default.removeItem(at: counter) }
	let path = counter.path

	let fake = FakeEventSource()
	let registry = PHEventRegistry(factory: { _ in fake })

	let block = try PHBlock.load(from: """
	[[block]]
	command = "n=$(cat \(path) 2>/dev/null || echo 0); n=$((n+1)); echo $n > \(path); echo $n"
	refresh = 0.2
	events = ["volume"]
	""")[0]
	block.registry = registry

	block.startAutoRefresh()
	try await Task.sleep(for: .milliseconds(50))

	let afterInitial = Int(block.label!.trimmingCharacters(in: .whitespacesAndNewlines)) ?? 0
	#expect(afterInitial == 1)
	#expect(fake.startCount == 1)

	// Both an event and the interval can drive updates independently.
	fake.fire()
	try await Task.sleep(for: .milliseconds(50))

	let afterEvent = Int(block.label!.trimmingCharacters(in: .whitespacesAndNewlines)) ?? 0
	#expect(afterEvent >= 2)

	block.stopAutoRefresh()
}