#pragma once

#include <chrono>
#include <condition_variable>
#include <cstdint>
#include <deque>
#include <filesystem>
#include <map>
#include <mutex>
#include <set>
#include <string>
#include <thread>
#include <vector>

#include "dCommonVars.h"
#include "json_fwd.hpp"
#include "UgcBricks.h"
#include "UgcJobs.h"
#include "UgcStorage.h"

/**
 * The UGC server's queue. The main thread (Update) takes pending rows from the database, gathers each one's input
 * (the stored LXFML, or a modular build's modules from the CDClient) and hands it to the worker threads; they make
 * and write the files; the main thread records the outcome in the database. Workers never touch the database, the
 * CDClient or the network.
 */
class UgcProcessor {
public:
	using Kind = UgcStorage::Kind;

	struct Config {
		uint32_t pollIntervalMs{ 2000 };
		uint32_t pollBatch{ 32 };
		uint32_t maxAttempts{ 3 };
		uint64_t maxStorageBytes{}; // 0: no limit
		size_t threads{ 2 };
	};

	/**
	 * What the workers may use; changed while running (Configure) when the settings are reloaded.
	 */
	struct Limits {
		double maxCpus{};            // CPUs the workers may use together on average (UgcThrottle); 0: no limit
		uint64_t maxMemoryBytes{};   // estimated memory of the jobs running at once; 0: no limit
		int nice{};                  // the workers' scheduling priority (Linux nice, 0 to 19)
		int pauseFromHour{ -1 };     // local hours in which no new jobs start (from, to; -1: never)
		int pauseToHour{ -1 };
	};

	UgcProcessor(Config config, UgcStorage& storage, UgcBricks::BrickLibrary& library, UgcJobs::Settings settings);
	~UgcProcessor();

	void Start();

	// Main thread: new settings and limits (config reload)
	void Configure(UgcJobs::Settings settings, Limits limits);
	// Waits for the jobs that are running; queued ones are dropped (they stay pending in the database)
	void Stop();

	// Main thread: poll, dispatch, record results, keep the storage under its cap
	void Update();

	enum class Availability {
		READY,   // the files are there
		QUEUED,  // it exists and is being made (again)
		UNKNOWN, // no such item, or it failed
	};

	// Main thread: whether an item's files can be served, queuing it to be made when it exists but they're missing
	Availability Request(Kind kind, LWOOBJID id);

	// Main thread: what the server is doing, for /status
	nlohmann::json Status() const;

	// Any thread: jobs waiting for a worker, and workers busy (traffic diagnostics)
	size_t Queued() const { std::lock_guard lock(m_Mutex); return m_Jobs.size(); }
	size_t Busy() const { std::lock_guard lock(m_Mutex); return m_Active; }
	size_t Threads() const { return m_Config.threads; }
	// Main thread: the process's CPU use (percent of one core) and resident memory, and the running jobs' estimate
	double CpuPercent() const { return m_CpuPercent; }
	static uint64_t ResidentBytes();
	uint64_t JobMemory() const { std::lock_guard lock(m_Mutex); return m_MemoryInUse; }
	bool Throttled() const;

	// Main thread: totals since the start and the files' size (traffic reports, then the dashboard and /metrics)
	uint64_t Made() const { return m_Made; }
	uint64_t Failed() const { return m_Failed; }
	uint64_t Evicted() const { return m_Evicted; }
	uint64_t StoredBytes() const { return m_StoredBytes; }
	uint64_t MaxStorageBytes() const { return m_Config.maxStorageBytes; }

private:
	struct Job {
		Kind kind{};
		LWOOBJID id{};
		uint32_t attempts{};
		std::string blob;               // models: the LXFML
		UgcJobs::ModularInput modular;  // modular builds
		uint64_t memory{};              // estimated bytes it needs
		size_t parts{};
	};

	struct Done {
		Kind kind{};
		LWOOBJID id{};
		uint32_t attempts{};
		UgcJobs::Outcome outcome;
		uint64_t bytes{};
		double milliseconds{};
	};

	void Poll();
	void Collect();
	void Record(const Done& done);
	void Worker();
	void SampleUsage();

	Config m_Config;
	UgcStorage& m_Storage;
	UgcBricks::BrickLibrary& m_Library;
	UgcJobs::Settings m_Settings; // guarded by m_Mutex (workers copy it per job)
	Limits m_Limits;              // guarded by m_Mutex

	mutable std::mutex m_Mutex;
	std::condition_variable m_Wake;
	std::deque<Job> m_Jobs;
	std::deque<Done> m_Done;
	size_t m_Active{};
	uint64_t m_MemoryInUse{};  // estimates of the running jobs
	uint64_t m_Waiting{};      // times a job waited for memory
	bool m_Paused{};           // main thread: in the pause hours
	// Main thread: process CPU use, measured between status reads
	std::chrono::steady_clock::time_point m_CpuSampled{};
	double m_CpuSeconds{};
	double m_CpuPercent{};
	bool m_Stopping{};
	std::vector<std::thread> m_Threads;

	// Main thread only
	std::set<std::pair<Kind, LWOOBJID>> m_InFlight;
	std::chrono::steady_clock::time_point m_NextPoll{};
	std::chrono::steady_clock::time_point m_NextEviction{};
	std::map<std::pair<Kind, LWOOBJID>, std::pair<std::chrono::steady_clock::time_point, Availability>> m_Recent; // answers for missing files
	uint64_t m_StoredBytes{};
	uint64_t m_Made{};
	uint64_t m_Failed{};
	uint64_t m_Evicted{};
	struct LogEntry {
		Kind kind{};
		LWOOBJID id{};
		bool ok{};
		double milliseconds{};
		std::string message;
		int64_t time{};
	};
	std::deque<LogEntry> m_Log; // the last results
};