// Copyright Epic Games, Inc. All Rights Reserved.

#include "top_cmd.h"

#include <zencore/compactbinary.h>
#include <zencore/fmtutils.h>
#include <zencore/logging.h>
#include <zencore/scopeguard.h>
#include <zencore/string.h>
#include <zencore/system.h>
#include <zencore/thread.h>
#include <zencore/uid.h>
#include <zenhttp/httpclient.h>
#include <zenutil/consoletui.h>
#include <zenutil/zenserverprocess.h>

#include <chrono>
#include <ctime>
#include <memory>

//////////////////////////////////////////////////////////////////////////

namespace zen {

namespace {

	struct RunningInstance
	{
		uint16_t	Port;
		uint32_t	Pid;
		std::string SessionId;
	};

	static std::vector<RunningInstance> CollectInstances(ZenServerState& State)
	{
		std::vector<RunningInstance> Instances;
		State.Snapshot([&](const ZenServerState::ZenServerEntry& Entry) {
			StringBuilder<25> SessionSB;
			Entry.GetSessionId().ToString(SessionSB);
			Instances.push_back({Entry.EffectiveListenPort.load(), Entry.Pid.load(), std::string(SessionSB.c_str())});
		});
		return Instances;
	}

	static std::string FormatCurrentTime()
	{
		std::time_t Now = std::time(nullptr);
		std::tm		Local{};
#if ZEN_PLATFORM_WINDOWS
		localtime_s(&Local, &Now);
#else
		localtime_r(&Now, &Local);
#endif
		char Buffer[20];
		std::strftime(Buffer, sizeof(Buffer), "%Y-%m-%d %H:%M:%S", &Local);
		return Buffer;
	}

	static void PrintHorizontalRule(uint32_t Cols)
	{
		// U+2500 BOX DRAWINGS LIGHT HORIZONTAL = \xe2\x94\x80 (3 bytes per glyph)
		ExtendableStringBuilder<512> Line;
		for (uint32_t i = 0; i < Cols; ++i)
		{
			Line.Append("\xe2\x94\x80");
		}
		printf("%s\n", Line.c_str());
	}

	struct ServerStats
	{
		// /health/info
		bool			 InfoAvailable = false;
		std::string_view DataRoot;
		std::string_view BuildVersion;

		// /stats/z$ -> cache
		bool	 CacheAvailable = false;
		uint64_t CacheHits		= 0;
		uint64_t CacheMisses	= 0;
		double	 CacheHitRatio	= 0.0;
		uint64_t CacheWrites	= 0;
		uint64_t CacheDiskSize	= 0;
		uint64_t CacheMemSize	= 0;
		uint64_t CacheRpcCount	= 0;
		uint64_t CacheRpcOps	= 0;

		// /stats/prj -> project store
		bool	 PrjAvailable	 = false;
		uint64_t PrjRequestCount = 0;
		uint64_t PrjDiskSize	 = 0;
		uint64_t PrjMemSize		 = 0;
		uint64_t PrjOpHits		 = 0;
		uint64_t PrjOpMisses	 = 0;
		uint64_t PrjOpWrites	 = 0;
		uint64_t PrjChunkHits	 = 0;
		uint64_t PrjChunkMisses	 = 0;
		uint64_t PrjChunkWrites	 = 0;

		// Owned buffers to keep string_views alive
		CbObject InfoObject;
		CbObject CacheObject;
		CbObject PrjObject;
	};

	static void FetchServerStats(HttpClient& Http, ServerStats& Stats)
	{
		// Fetch /health/info
		try
		{
			if (HttpClient::Response Response = Http.Get("/health/info"))
			{
				Stats.InfoObject	= Response.AsObject();
				Stats.DataRoot		= Stats.InfoObject["DataRoot"].AsString();
				Stats.BuildVersion	= Stats.InfoObject["BuildVersion"].AsString();
				Stats.InfoAvailable = true;
			}
		}
		catch (...)
		{
		}

		// Fetch /stats/z$
		try
		{
			if (HttpClient::Response Response = Http.Get("/stats/z$"))
			{
				Stats.CacheObject	   = Response.AsObject();
				CbObjectView CacheView = Stats.CacheObject["cache"].AsObjectView();
				Stats.CacheHits		   = CacheView["hits"].AsUInt64(0);
				Stats.CacheMisses	   = CacheView["misses"].AsUInt64(0);
				Stats.CacheHitRatio	   = CacheView["hit_ratio"].AsDouble(0.0);
				Stats.CacheWrites	   = CacheView["writes"].AsUInt64(0);

				CbObjectView SizeView = CacheView["size"].AsObjectView();
				Stats.CacheDiskSize	  = SizeView["disk"].AsUInt64(0);
				Stats.CacheMemSize	  = SizeView["memory"].AsUInt64(0);

				CbObjectView RpcView = CacheView["rpc"].AsObjectView();
				Stats.CacheRpcCount	 = RpcView["count"].AsUInt64(0);
				Stats.CacheRpcOps	 = RpcView["ops"].AsUInt64(0);

				Stats.CacheAvailable = true;
			}
		}
		catch (...)
		{
		}

		// Fetch /stats/prj
		try
		{
			if (HttpClient::Response Response = Http.Get("/stats/prj"))
			{
				Stats.PrjObject		   = Response.AsObject();
				CbObjectView StoreView = Stats.PrjObject["store"].AsObjectView();

				Stats.PrjRequestCount = StoreView["requestcount"].AsUInt64(0);

				CbObjectView SizeView = StoreView["size"].AsObjectView();
				Stats.PrjDiskSize	  = SizeView["disk"].AsUInt64(0);
				Stats.PrjMemSize	  = SizeView["memory"].AsUInt64(0);

				CbObjectView OpView = StoreView["op"].AsObjectView();
				Stats.PrjOpHits		= OpView["hitcount"].AsUInt64(0);
				Stats.PrjOpMisses	= OpView["misscount"].AsUInt64(0);
				Stats.PrjOpWrites	= OpView["writecount"].AsUInt64(0);

				CbObjectView ChunkView = StoreView["chunk"].AsObjectView();
				Stats.PrjChunkHits	   = ChunkView["hitcount"].AsUInt64(0);
				Stats.PrjChunkMisses   = ChunkView["misscount"].AsUInt64(0);
				Stats.PrjChunkWrites   = ChunkView["writecount"].AsUInt64(0);

				Stats.PrjAvailable = true;
			}
		}
		catch (...)
		{
		}
	}

	static HttpClientSettings MakeQuickSettings()
	{
		HttpClientSettings Settings;
		Settings.ConnectTimeout = std::chrono::milliseconds(2000);
		Settings.Timeout		= std::chrono::milliseconds(3000);
		return Settings;
	}

}  // namespace

TopCommand::TopCommand()
{
	m_Options.add_options()("h,help", "Print help");
	m_Options.add_option("", "u", "hosturl", "Host URL", cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
	m_Options
		.add_option("", "i", "interval", "Refresh interval in milliseconds", cxxopts::value(m_IntervalMs)->default_value("1000"), "<ms>");
}

TopCommand::~TopCommand() = default;

void
TopCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
{
	ZEN_UNUSED(GlobalOptions);

	if (!ParseOptions(argc, argv))
	{
		return;
	}

	if (m_IntervalMs < 100)
	{
		m_IntervalMs = 100;
	}

	// Gather system metrics
	SystemMetrics SysMetrics = GetSystemMetrics();

	// Gather running instances
	ZenServerState State;
	bool		   HasState = State.InitializeReadOnly();

	// Collect instances and determine initial target
	std::vector<RunningInstance> Instances;
	if (HasState)
	{
		Instances = CollectInstances(State);
	}

	// Resolve the host to connect to. If -u was given, use that directly.
	// Otherwise auto-discover from running instances.
	std::string ActiveHost	= m_HostName;
	int			SelectedIdx = -1;  // index into Instances; -1 = explicit host or none

	if (ActiveHost.empty() && !Instances.empty())
	{
		SelectedIdx = 0;
		ActiveHost	= fmt::format("http://localhost:{}", Instances[0].Port);
	}
	else if (!ActiveHost.empty())
	{
		ActiveHost = ResolveTargetHostSpec(ActiveHost);
	}

	// If not an interactive terminal, print a single snapshot and exit
	if (!IsTuiAvailable())
	{
		printf("zen top");
		if (!ActiveHost.empty())
		{
			printf(" - %s", ActiveHost.c_str());
		}
		printf(" - %s\n", FormatCurrentTime().c_str());

		printf("System: %u CPU, %u cores, %u LPs | Memory: %llu MiB (%llu avail)\n",
			   SysMetrics.CpuCount,
			   SysMetrics.CoreCount,
			   SysMetrics.LogicalProcessorCount,
			   (unsigned long long)SysMetrics.SystemMemoryMiB,
			   (unsigned long long)SysMetrics.AvailSystemMemoryMiB);

		if (!Instances.empty())
		{
			printf("\nInstances:\n");
			printf("  %5s %7s %s\n", "PORT", "PID", "SESSION");
			for (const auto& Inst : Instances)
			{
				printf("  %5u %7u %s\n", Inst.Port, Inst.Pid, Inst.SessionId.c_str());
			}
		}

		if (!ActiveHost.empty())
		{
			HttpClient	Http(ActiveHost, MakeQuickSettings());
			ServerStats Stats;
			FetchServerStats(Http, Stats);

			if (Stats.CacheAvailable)
			{
				printf("\nCache (z$):\n");
				printf("  Hits: %llu  Misses: %llu  Hit Ratio: %.1f%%  Writes: %llu\n",
					   (unsigned long long)Stats.CacheHits,
					   (unsigned long long)Stats.CacheMisses,
					   Stats.CacheHitRatio * 100.0,
					   (unsigned long long)Stats.CacheWrites);
				printf("  Disk: %s  Memory: %s\n", NiceBytes(Stats.CacheDiskSize).c_str(), NiceBytes(Stats.CacheMemSize).c_str());
				printf("  RPC: %llu requests, %llu ops\n", (unsigned long long)Stats.CacheRpcCount, (unsigned long long)Stats.CacheRpcOps);
			}

			if (Stats.PrjAvailable)
			{
				printf("\nProject Store:\n");
				printf("  Requests: %llu  Disk: %s  Memory: %s\n",
					   (unsigned long long)Stats.PrjRequestCount,
					   NiceBytes(Stats.PrjDiskSize).c_str(),
					   NiceBytes(Stats.PrjMemSize).c_str());
				printf("  Ops: %llu hits, %llu misses, %llu writes\n",
					   (unsigned long long)Stats.PrjOpHits,
					   (unsigned long long)Stats.PrjOpMisses,
					   (unsigned long long)Stats.PrjOpWrites);
				printf("  Chunks: %llu hits, %llu misses, %llu writes\n",
					   (unsigned long long)Stats.PrjChunkHits,
					   (unsigned long long)Stats.PrjChunkMisses,
					   (unsigned long long)Stats.PrjChunkWrites);
			}
		}

		return;
	}

	// Enter fullscreen alternate-screen mode
	TuiEnterAlternateScreen();
	auto ExitGuard = MakeGuard([]() { TuiExitAlternateScreen(); });

	// Create HTTP client for the active host
	std::unique_ptr<HttpClient> Http;
	auto						RecreateClient = [&]() {
		   if (!ActiveHost.empty())
		   {
			   Http = std::make_unique<HttpClient>(ActiveHost, MakeQuickSettings());
		   }
		   else
		   {
			   Http.reset();
		   }
	};
	RecreateClient();

	bool NeedsRedraw = true;

	// Main refresh loop
	for (;;)
	{
		if (NeedsRedraw)
		{
			uint32_t Cols = TuiConsoleColumns();

			TuiCursorHome();

			// Fetch fresh system metrics each iteration
			SysMetrics = GetSystemMetrics();

			// Refresh instance list
			if (HasState)
			{
				if (!State.IsReadOnly())
				{
					State.Sweep();
				}
				Instances = CollectInstances(State);

				// Clamp selection
				if (SelectedIdx >= static_cast<int>(Instances.size()))
				{
					SelectedIdx = static_cast<int>(Instances.size()) - 1;
				}
			}

			// Fetch server stats
			ServerStats Stats;
			if (Http)
			{
				FetchServerStats(*Http, Stats);
			}

			// Header line
			{
				ExtendableStringBuilder<256> Header;
				Header << "zen top";
				if (!ActiveHost.empty())
				{
					Header << " - " << ActiveHost;
				}
				if (Stats.InfoAvailable && !Stats.BuildVersion.empty())
				{
					Header << " - " << Stats.BuildVersion;
				}
				Header << " - " << FormatCurrentTime();
				printf("%-*s\n", Cols, Header.c_str());
			}

			PrintHorizontalRule(Cols);

			// System metrics
			printf("System: %u CPU, %u cores, %u LPs | Memory: %llu MiB (%llu avail)\033[K\n",
				   SysMetrics.CpuCount,
				   SysMetrics.CoreCount,
				   SysMetrics.LogicalProcessorCount,
				   (unsigned long long)SysMetrics.SystemMemoryMiB,
				   (unsigned long long)SysMetrics.AvailSystemMemoryMiB);

			// Running instances
			printf("\033[K\n");
			if (!Instances.empty())
			{
				bool MultipleInstances = (Instances.size() > 1 && SelectedIdx >= 0);
				if (MultipleInstances)
				{
					printf("\033[1mInstances:\033[0m \033[2m(\xe2\x86\x91/\xe2\x86\x93 to switch)\033[0m\033[K\n");
				}
				else
				{
					printf("\033[1mInstances:\033[0m\033[K\n");
				}
				printf("  %5s %7s %s\033[K\n", "PORT", "PID", "SESSION");
				for (int i = 0; i < static_cast<int>(Instances.size()); ++i)
				{
					const auto& Inst	   = Instances[i];
					bool		IsSelected = (i == SelectedIdx);
					if (IsSelected)
					{
						// Highlight: bold + reverse video
						printf("\033[1;7m");
					}
					printf("  %5u %7u %s\033[K", Inst.Port, Inst.Pid, Inst.SessionId.c_str());
					if (IsSelected)
					{
						printf("\033[0m");
					}
					printf("\n");
				}
			}
			else
			{
				printf("  No Zen instances found\033[K\n");
			}

			// Cache stats
			printf("\033[K\n");
			if (Stats.CacheAvailable)
			{
				printf("\033[1mCache (z$):\033[0m\033[K\n");
				printf("  Hits: %-10llu Misses: %-10llu Hit Ratio: %-7.1f%% Writes: %llu\033[K\n",
					   (unsigned long long)Stats.CacheHits,
					   (unsigned long long)Stats.CacheMisses,
					   Stats.CacheHitRatio * 100.0,
					   (unsigned long long)Stats.CacheWrites);
				printf("  Disk: %-12s Memory: %s\033[K\n", NiceBytes(Stats.CacheDiskSize).c_str(), NiceBytes(Stats.CacheMemSize).c_str());
				printf("  RPC: %llu requests, %llu ops\033[K\n",
					   (unsigned long long)Stats.CacheRpcCount,
					   (unsigned long long)Stats.CacheRpcOps);
			}
			else if (Http)
			{
				printf("\033[1mCache (z$):\033[0m unavailable\033[K\n");
			}

			// Project store stats
			printf("\033[K\n");
			if (Stats.PrjAvailable)
			{
				printf("\033[1mProject Store:\033[0m\033[K\n");
				printf("  Requests: %-10llu Disk: %-12s Memory: %s\033[K\n",
					   (unsigned long long)Stats.PrjRequestCount,
					   NiceBytes(Stats.PrjDiskSize).c_str(),
					   NiceBytes(Stats.PrjMemSize).c_str());
				printf("  Ops:    %llu hits, %llu misses, %llu writes\033[K\n",
					   (unsigned long long)Stats.PrjOpHits,
					   (unsigned long long)Stats.PrjOpMisses,
					   (unsigned long long)Stats.PrjOpWrites);
				printf("  Chunks: %llu hits, %llu misses, %llu writes\033[K\n",
					   (unsigned long long)Stats.PrjChunkHits,
					   (unsigned long long)Stats.PrjChunkMisses,
					   (unsigned long long)Stats.PrjChunkWrites);
			}
			else if (Http)
			{
				printf("\033[1mProject Store:\033[0m unavailable\033[K\n");
			}

			// Server info
			if (Stats.InfoAvailable && !Stats.DataRoot.empty())
			{
				printf("\033[K\n");
				printf("  Data root: %.*s\033[K\n", static_cast<int>(Stats.DataRoot.size()), Stats.DataRoot.data());
			}

			// Clear any stale content below
			TuiClearToBottom();

			// Footer (print at bottom by moving cursor)
			{
				uint32_t Rows = TuiConsoleRows();
				printf("\033[%u;1H", Rows);	 // Move to last row
				if (Instances.size() > 1 && SelectedIdx >= 0)
				{
					printf("\033[2mq quit | \xe2\x86\x91/\xe2\x86\x93 switch instance | F5 refresh | Refreshing every %.1fs\033[0m\033[K",
						   static_cast<double>(m_IntervalMs) / 1000.0);
				}
				else
				{
					printf("\033[2mq quit | F5 refresh | Refreshing every %.1fs\033[0m\033[K", static_cast<double>(m_IntervalMs) / 1000.0);
				}
			}

			fflush(stdout);
			NeedsRedraw = false;
		}

		// Wait for input or next tick, whichever comes first.
		// Uses TuiWaitForInput() which blocks on the OS input handle, so keypresses
		// are detected immediately rather than waiting for a sleep interval to elapse.
		auto TickStart = std::chrono::steady_clock::now();
		for (;;)
		{
			TuiInput Input = TuiPollInput();
			if (Input == TuiInput::Quit)
			{
				return;
			}
			if (Input == TuiInput::Refresh)
			{
				NeedsRedraw = true;
				break;
			}
			if (Input == TuiInput::ArrowUp || Input == TuiInput::ArrowDown)
			{
				// Only handle arrow keys when we have auto-discovered instances to switch between
				if (SelectedIdx >= 0 && Instances.size() > 1)
				{
					int Count = static_cast<int>(Instances.size());
					if (Input == TuiInput::ArrowUp)
					{
						SelectedIdx = (SelectedIdx - 1 + Count) % Count;
					}
					else
					{
						SelectedIdx = (SelectedIdx + 1) % Count;
					}
					ActiveHost = fmt::format("http://localhost:{}", Instances[SelectedIdx].Port);
					RecreateClient();
					NeedsRedraw = true;
					break;
				}
			}

			auto	 Now	   = std::chrono::steady_clock::now();
			uint32_t ElapsedMs = static_cast<uint32_t>(std::chrono::duration_cast<std::chrono::milliseconds>(Now - TickStart).count());
			if (ElapsedMs >= m_IntervalMs)
			{
				break;
			}

			TuiWaitForInput(m_IntervalMs - ElapsedMs);
		}

		// Schedule a full redraw for the next iteration
		NeedsRedraw = true;
	}
}

//////////////////////////////////////////////////////////////////////////

PsCommand::PsCommand()
{
}

PsCommand::~PsCommand() = default;

void
PsCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
{
	ZEN_UNUSED(GlobalOptions, argc, argv);

	ZenServerState State;
	if (!State.InitializeReadOnly())
	{
		ZEN_CONSOLE("No Zen state found");

		return;
	}

	State.Snapshot([&](const ZenServerState::ZenServerEntry& Entry) {
		ZEN_CONSOLE("Port {} : pid {}", Entry.EffectiveListenPort.load(), Entry.Pid.load());
	});
}

}  // namespace zen