#pragma once

#include "AppConfig.h"
#include "AppConfigJson.h"
#include "AppConfigProvider.h"
#include "AppRestart.h"
#include "RenderCadenceHttpRoutes.h"
#include "RuntimeContentController.h"
#include "../logging/Logger.h"
#include "../control/RuntimeStateJson.h"
#include "../control/osc/OscControlServer.h"
#include "../json/JsonWriter.h"
#include "../preview/PreviewWindowThread.h"
#include "../telemetry/TelemetryHealthMonitor.h"
#include "../video/ndi/NdiSourceDiscovery.h"
#include "VideoIOEdges.h"
#include "VideoOutputThread.h"

#include <atomic>
#include <chrono>
#include <filesystem>
#include <functional>
#include <memory>
#include <string>
#include <thread>
#include <type_traits>
#include <vector>

namespace RenderCadenceCompositor
{
namespace detail
{
template <typename RenderThread>
auto StartRenderThread(RenderThread& renderThread, std::string& error, int) -> decltype(renderThread.Start(error), bool())
{
	return renderThread.Start(error);
}

template <typename RenderThread>
bool StartRenderThreadWithoutError(RenderThread& renderThread, std::true_type)
{
	return renderThread.Start();
}

template <typename RenderThread>
bool StartRenderThreadWithoutError(RenderThread& renderThread, std::false_type)
{
	renderThread.Start();
	return true;
}

template <typename RenderThread>
auto StartRenderThread(RenderThread& renderThread, std::string&, long) -> decltype(renderThread.Start(), bool())
{
	return StartRenderThreadWithoutError(renderThread, std::is_same<decltype(renderThread.Start()), bool>());
}
}

template <typename RenderThread, typename SystemFrameExchange>
class RenderCadenceApp
{
public:
	RenderCadenceApp(
		RenderThread& renderThread,
		SystemFrameExchange& frameExchange,
		AppConfig config,
		std::unique_ptr<IVideoOutputEdge> output,
		std::unique_ptr<IRuntimeContentController> runtimeContent,
		std::filesystem::path configPath = std::filesystem::path()) :
		mRenderThread(renderThread),
		mFrameExchange(frameExchange),
		mConfig(config),
		mConfigPath(std::move(configPath)),
		mOutput(std::move(output)),
		mRuntimeContent(std::move(runtimeContent)),
		mOutputThread(*mOutput, mFrameExchange, VideoOutputThreadConfig{
			mConfig.outputThread.targetBufferedFrames,
			mConfig.outputThread.idleSleep
		}),
		mTelemetryHealth(mConfig.telemetry)
	{
	}

	RenderCadenceApp(const RenderCadenceApp&) = delete;
	RenderCadenceApp& operator=(const RenderCadenceApp&) = delete;

	~RenderCadenceApp()
	{
		Stop();
	}

	bool Start(std::string& error)
	{
		if (mRuntimeContent)
			mRuntimeContent->Initialize(mConfig);

		Log("app", "Starting render thread.");
		if (!detail::StartRenderThread(mRenderThread, error, 0))
		{
			LogError("app", "Render thread start failed: " + error);
			Stop();
			return false;
		}
		if (mRuntimeContent)
			mRuntimeContent->Start();

		if (!BuildSettledOutputReserve(error))
		{
			LogError("app", error);
			Stop();
			return false;
		}

		StartPreviewWindow();
		StartOptionalVideoOutput();
		mTelemetryHealth.Start(mFrameExchange, *mOutput, mOutputThread, mRenderThread);
		StartOscServer();
		StartHttpServer();
		Log("app", "RenderCadenceCompositor started.");
		mStarted = true;
		return true;
	}

	void Stop()
	{
		mHttpServer.Stop();
		mOscServer.Stop();
		mTelemetryHealth.Stop();
		mPreviewWindow.Stop();
		mOutputThread.Stop();
		mOutput->Stop();
		if (mRuntimeContent)
			mRuntimeContent->Stop();
		mRenderThread.Stop();
		mOutput->ReleaseResources();
		if (mStarted)
			Log("app", "RenderCadenceCompositor shutdown complete.");
		mStarted = false;
	}

	bool Started() const { return mStarted; }
	const IVideoOutputEdge& Output() const { return *mOutput; }
	void SetVideoInputMetricsProvider(std::function<VideoInputEdgeMetrics()> provider)
	{
		mVideoInputMetricsProvider = std::move(provider);
	}

private:
	void StartOptionalVideoOutput()
	{
		if (mConfig.output.backend == "none")
		{
			mVideoOutputEnabled = false;
			mVideoOutputStatus = "Video output backend disabled by config.";
			Log("app", mVideoOutputStatus);
			return;
		}

		std::string outputError;
		Log("app", "Initializing optional video output backend: " + mConfig.output.backend + ".");
		VideoOutputEdgeConfig outputConfig;
		outputConfig.outputVideoMode = mConfig.output.videoMode;
		outputConfig.systemFramePixelFormat = mConfig.output.systemFramePixelFormat;
		outputConfig.externalKeyingEnabled = mConfig.output.externalKeyingEnabled;
		outputConfig.outputAlphaRequired = mConfig.output.outputAlphaRequired;
		if (!mOutput->Initialize(
			outputConfig,
			[this](const VideoIOCompletion& completion) {
				mFrameExchange.ReleaseScheduledByBytes(completion.outputFrameBuffer);
			},
			outputError))
		{
			DisableVideoOutput("Video output unavailable: " + outputError);
			return;
		}

		if (mOutput->RequiresPreroll())
		{
			Log("app", "Starting video output thread.");
			if (!mOutputThread.Start())
			{
				DisableVideoOutput("Video output thread failed to start.");
				return;
			}

			Log("app", "Waiting for video output preroll frames.");
			if (!WaitForPreroll())
			{
				DisableVideoOutput("Timed out waiting for video output preroll frames.");
				return;
			}

			Log("app", "Starting scheduled video playback.");
			if (!mOutput->StartScheduledPlayback(outputError))
			{
				DisableVideoOutput("Scheduled video playback failed: " + outputError);
				return;
			}
		}
		else
		{
			Log("app", "Starting video output backend without preroll.");
			if (!mOutput->StartScheduledPlayback(outputError))
			{
				DisableVideoOutput("Video output failed to start: " + outputError);
				return;
			}
			if (!mOutputThread.Start())
			{
				DisableVideoOutput("Video output thread failed to start.");
				return;
			}
		}

		mVideoOutputEnabled = true;
		mVideoOutputStatus = mConfig.output.backend + " scheduled output running.";
		Log("app", mVideoOutputStatus);
		Log(
			"app",
			"Video output mode: " + mOutput->State().outputDisplayModeName +
				", frame budget " + std::to_string(mOutput->State().frameBudgetMilliseconds) + " ms.");
	}

	bool BuildSettledOutputReserve(std::string& error)
	{
		const auto reserveTimeout = mConfig.warmupTimeout;
		Log("app",
			"Building output preroll reserve: waiting for " + std::to_string(mConfig.warmupCompletedFrames) +
			" completed frame(s).");
		if (mFrameExchange.WaitForCompletedDepth(mConfig.warmupCompletedFrames, reserveTimeout))
		{
			return true;
		}

		error = "Timed out waiting for output preroll reserve.";
		return false;
	}

	void DisableVideoOutput(const std::string& reason)
	{
		mOutputThread.Stop();
		mOutput->Stop();
		mOutput->ReleaseResources();
		mFrameExchange.Clear();
		mVideoOutputEnabled = false;
		mVideoOutputStatus = reason;
		LogWarning("app", reason + " Continuing without video output.");
	}

	void StartHttpServer()
	{
		RenderCadenceHttpRouteCallbacks routeCallbacks;
		routeCallbacks.getStateJson = [this]() {
			return BuildStateJson();
		};
		routeCallbacks.getConfigJson = [this]() {
			return BuildConfigJson();
		};
		routeCallbacks.getNdiSourcesJson = [this]() {
			return BuildNdiSourcesJson();
		};
		routeCallbacks.resolveShaderAssetPath = [this](
			const std::string& shaderId,
			const std::string& assetPath,
			std::filesystem::path& resolvedPath,
			std::string& assetError) {
			if (!mRuntimeContent)
			{
				assetError = "No runtime content controller is active.";
				return false;
			}
			return mRuntimeContent->ResolveAssetPath(shaderId, assetPath, resolvedPath, assetError);
		};
		routeCallbacks.executePost = [this](const std::string& path, const std::string& body) {
			if (path == "/api/config/save")
				return HandleConfigSave(body);
			if (path == "/api/app/restart")
				return HandleAppRestart();

			if (mRuntimeContent)
				return mRuntimeContent->HandlePost(path, body);
			return ControlActionResult{ false, "No runtime content controller is active." };
		};

		HttpControlServerCallbacks callbacks;
		callbacks.getWebSocketStateJson = routeCallbacks.getStateJson;
		callbacks.routeRequest = [this, routeCallbacks](const HttpRequest& request) {
			return RouteRenderCadenceHttpRequest(request, mHttpServer, routeCallbacks);
		};

		std::string error;
		if (!mHttpServer.Start(
			FindRepoPath("ui/dist"),
			FindRepoPath("docs"),
			mConfig.http,
			callbacks,
			error))
		{
			LogWarning("http", "HTTP control server did not start: " + error);
			return;
		}
	}

	void StartPreviewWindow()
	{
		if (!mConfig.previewEnabled)
			return;

		PreviewWindowConfig previewConfig;
		previewConfig.enabled = true;
		previewConfig.fps = mConfig.previewFps;
		std::string error;
		if (mPreviewWindow.Start(mFrameExchange, previewConfig, error))
		{
			Log("preview", "Preview window thread started.");
			return;
		}

		LogWarning("preview", "Preview window did not start: " + error);
	}

	std::string BuildStateJson()
	{
		CadenceTelemetrySnapshot telemetry = mHttpTelemetry.Sample(mFrameExchange, *mOutput, mOutputThread, mRenderThread);
		ApplyVideoInputMetrics(telemetry);
		RuntimeStateJsonInput stateInput{
			mConfig,
			telemetry,
			mHttpServer.Port(),
			mVideoOutputEnabled,
			mVideoOutputStatus,
			&mOscServer.State()
		};
		if (mRuntimeContent)
		{
			stateInput.writeRuntimeJson = [this, telemetry](JsonWriter& writer) {
				mRuntimeContent->WriteRuntimeJson(writer, telemetry);
			};
			stateInput.writeCatalogJson = [this](JsonWriter& writer) {
				mRuntimeContent->WriteCatalogJson(writer);
			};
			stateInput.writeLayersJson = [this, telemetry](JsonWriter& writer) {
				mRuntimeContent->WriteLayersJson(writer, telemetry);
			};
		}
		return RuntimeStateToJson(stateInput);
	}

	void StartOscServer()
	{
		OscControlServerConfig oscConfig;
		oscConfig.bindAddress = mConfig.oscBindAddress;
		oscConfig.port = mConfig.oscPort;
		oscConfig.smoothing = mConfig.oscSmoothing;

		std::string error;
		if (!mOscServer.Start(oscConfig, error))
		{
			LogWarning("osc", "OSC control stub did not start: " + error);
			return;
		}

		if (!mOscServer.State().statusMessage.empty())
			Log("osc", mOscServer.State().statusMessage);
	}

	std::string BuildConfigJson() const
	{
		AppConfig diskConfig = mConfig;
		std::string loadError;
		bool diskLoaded = false;
		if (!mConfigPath.empty())
		{
			AppConfigProvider provider;
			diskLoaded = provider.Load(mConfigPath, loadError);
			if (diskLoaded)
				diskConfig = provider.Config();
		}

		JsonValue root = JsonValue::MakeObject();
		root.set("ok", JsonValue(true));
		root.set("path", JsonValue(mConfigPath.string()));
		root.set("active", AppConfigToJsonValue(mConfig));
		root.set("disk", AppConfigToJsonValue(diskConfig));
		root.set("diskLoaded", JsonValue(diskLoaded));
		root.set("restartRequired", JsonValue(mRestartRequired.load(std::memory_order_relaxed)));
		if (!loadError.empty())
			root.set("error", JsonValue(loadError));
		return SerializeJson(root);
	}

	std::string BuildNdiSourcesJson() const
	{
		std::vector<NdiSourceInfo> sources;
		std::string error;
		const bool discovered = DiscoverNdiSources(sources, error);

		JsonWriter writer;
		writer.BeginObject();
		writer.KeyBool("ok", discovered);
		if (!error.empty())
			writer.KeyString("error", error);
		writer.Key("sources");
		writer.BeginArray();
		for (const NdiSourceInfo& source : sources)
		{
			writer.BeginObject();
			writer.KeyString("name", source.name);
			writer.KeyString("urlAddress", source.urlAddress);
			writer.EndObject();
		}
		writer.EndArray();
		writer.EndObject();
		return writer.StringValue();
	}

	ControlActionResult HandleConfigSave(const std::string& body)
	{
		AppConfig nextConfig;
		std::string error;
		if (!ParseAppConfigJson(body, nextConfig, error))
			return ControlActionResult{ false, error };

		if (!SaveAppConfigToFile(nextConfig, mConfigPath, error))
			return ControlActionResult{ false, error };

		mRestartRequired.store(true, std::memory_order_relaxed);
		Log("app", "Saved runtime host config to " + mConfigPath.string() + "; restart required for startup-owned services.");
		return ControlActionResult{ true };
	}

	ControlActionResult HandleAppRestart()
	{
		std::string error;
		if (!ScheduleProcessRestart(error))
			return ControlActionResult{ false, error };

		Log("app", "App restart requested from HTTP control.");
		return ControlActionResult{ true };
	}

	void ApplyVideoInputMetrics(CadenceTelemetrySnapshot& telemetry)
	{
		if (!mVideoInputMetricsProvider)
			return;

		const VideoInputEdgeMetrics inputMetrics = mVideoInputMetricsProvider();
		telemetry.inputConvertMilliseconds = inputMetrics.convertMilliseconds;
		telemetry.inputSubmitMilliseconds = inputMetrics.submitMilliseconds;
		telemetry.inputNoSignalFrames = inputMetrics.noInputSourceFrames;
		telemetry.inputUnsupportedFrames = inputMetrics.unsupportedFrames;
		telemetry.inputSubmitMisses = inputMetrics.submitMisses;
		telemetry.inputCaptureFormat = inputMetrics.captureFormat ? inputMetrics.captureFormat : "none";
		if (telemetry.sampleSeconds > 0.0)
			telemetry.inputCaptureFps = static_cast<double>(inputMetrics.capturedFrames - mLastInputCapturedFrames) / telemetry.sampleSeconds;
		mLastInputCapturedFrames = inputMetrics.capturedFrames;
	}

	bool WaitForPreroll() const
	{
		const auto deadline = std::chrono::steady_clock::now() + mConfig.prerollTimeout;
		while (std::chrono::steady_clock::now() < deadline)
		{
			if (mFrameExchange.Metrics().scheduledCount >= mConfig.outputThread.targetBufferedFrames)
				return true;
			std::this_thread::sleep_for(mConfig.prerollPoll);
		}
		return false;
	}

	RenderThread& mRenderThread;
	SystemFrameExchange& mFrameExchange;
	AppConfig mConfig;
	std::filesystem::path mConfigPath;
	std::unique_ptr<IVideoOutputEdge> mOutput;
	std::unique_ptr<IRuntimeContentController> mRuntimeContent;
	VideoOutputThread<SystemFrameExchange> mOutputThread;
	TelemetryHealthMonitor mTelemetryHealth;
	CadenceTelemetry mHttpTelemetry;
	HttpControlServer mHttpServer;
	OscControlServer mOscServer;
	PreviewWindowThread mPreviewWindow;
	std::function<VideoInputEdgeMetrics()> mVideoInputMetricsProvider;
	uint64_t mLastInputCapturedFrames = 0;
	std::atomic<bool> mRestartRequired{ false };
	bool mStarted = false;
	bool mVideoOutputEnabled = false;
	std::string mVideoOutputStatus = "Video output not started.";
};
}