// EQ2Emulator: Everquest II Server Emulator - Copyright (C) 2007 EQ2EMulator Development Team (http://www.eq2emulator.net) - GPL v3

#pragma once

#include <cstdio>
#include <cstring>
#include <map>
#include <string>
#include <mutex>
#include <memory>

#include "emu_opcodes.hpp"
#include "../debug.hpp"
#include "../types.hpp"
#include "../log.hpp"

#if defined(SHARED_OPCODES) && !defined(EQ2)
	#include "EMuShareMem.h"
	extern LoadEMuShareMemDLL EMuShareMemDLL;
#endif

using namespace std;

// Base opcode manager class providing common functionality for opcode translation
class OpcodeManager
{
public:
	// Constructor initializes the manager to an unloaded state
	OpcodeManager();
	virtual ~OpcodeManager() {}
	
	// Returns whether this manager supports opcode modification at runtime
	virtual bool Mutable() { return false; }
	
	// Load opcodes from a file containing opcode definitions
	virtual bool LoadOpcodes(const char *filename) = 0;
	
	// Load opcodes from a pre-parsed map of opcode names to values
	virtual bool LoadOpcodes(map<string, uint16>* eq, std::string* missingOpcodes = nullptr) = 0;
	
	// Reload opcodes from file, typically used for runtime updates
	virtual bool ReloadOpcodes(const char *filename) = 0;
	
	// Convert emulator opcode to EverQuest client opcode
	virtual uint16 EmuToEQ(const EmuOpcode emu_op) = 0;
	
	// Convert EverQuest client opcode to emulator opcode
	virtual EmuOpcode EQToEmu(const uint16 eq_op) = 0;
	
	// Convert emulator opcode to human-readable name
	static const char *EmuToName(const EmuOpcode emu_op);
	
	// Convert EverQuest opcode to human-readable name via emulator opcode lookup
	const char *EQToName(const uint16 emu_op);
	
	// Find emulator opcode by name (case-insensitive search)
	EmuOpcode NameSearch(const char *name);
	
	// Strategy pattern interface for setting opcodes during loading
	class OpcodeSetStrategy
	{
	public:
		// Set mapping between emulator and EverQuest opcodes
		virtual void Set(EmuOpcode emu_op, uint16 eq_op) = 0;
		virtual ~OpcodeSetStrategy() {}
	};

protected:
	bool loaded;				// True when opcodes have been successfully loaded
	std::mutex MOpcodes;		// Mutex protecting opcode data structures
	
	// Load opcodes from file using specified strategy for storage
	static bool LoadOpcodesFile(const char *filename, OpcodeSetStrategy *s);
	
	// Load opcodes from map using specified strategy for storage
	static bool LoadOpcodesMap(map<string, uint16>* eq, OpcodeSetStrategy *s, std::string* missingOpcodes = nullptr);
};

// Opcode manager that supports runtime modification of opcode mappings
class MutableOpcodeManager : public OpcodeManager
{
public:
	MutableOpcodeManager() : OpcodeManager() {}
	
	// Returns true indicating this manager supports runtime modifications
	virtual bool Mutable() { return true; }
	
	// Set individual opcode mapping at runtime
	virtual void SetOpcode(EmuOpcode emu_op, uint16 eq_op) = 0;
};

#ifdef SHARED_OPCODES
// Opcode manager using shared memory for inter-process opcode sharing
class SharedOpcodeManager : public OpcodeManager
{
public:
	virtual ~SharedOpcodeManager() {}
	
	// Load opcodes from file into shared memory
	virtual bool LoadOpcodes(const char *filename);
	
	// Load opcodes from map into shared memory
	virtual bool LoadOpcodes(map<string, uint16>* eq, std::string* missingOpcodes = nullptr);
	
	// Reload opcodes from file into shared memory
	virtual bool ReloadOpcodes(const char *filename);
	
	// Convert emulator opcode to EverQuest opcode using shared memory lookup
	virtual uint16 EmuToEQ(const EmuOpcode emu_op);
	
	// Convert EverQuest opcode to emulator opcode using shared memory lookup
	virtual EmuOpcode EQToEmu(const uint16 eq_op);
	
protected:
	// Strategy for storing opcodes in shared memory
	class SharedMemStrategy : public OpcodeManager::OpcodeSetStrategy
	{
	public:
		// Store opcode mapping in shared memory
		void Set(EmuOpcode emu_op, uint16 eq_op);
	};
	
	// Callback for DLL-based opcode loading
	static bool DLLLoadOpcodesCallback(const char *filename);
};
#endif

// Standard opcode manager using heap memory for opcode storage
class RegularOpcodeManager : public MutableOpcodeManager
{
public:
	// Constructor allocates memory for opcode translation tables
	RegularOpcodeManager();
	
	// Destructor cleans up allocated memory
	virtual ~RegularOpcodeManager();
	
	// Returns true indicating opcodes can be edited
	virtual bool Editable() { return true; }
	
	// Load opcodes from file into memory arrays
	virtual bool LoadOpcodes(const char *filename);
	
	// Load opcodes from map into memory arrays
	virtual bool LoadOpcodes(map<string, uint16>* eq, std::string* missingOpcodes = nullptr);
	
	// Reload opcodes from file, preserving existing mappings where possible
	virtual bool ReloadOpcodes(const char *filename);
	
	// Convert emulator opcode to EverQuest opcode using array lookup
	virtual uint16 EmuToEQ(const EmuOpcode emu_op);
	
	// Convert EverQuest opcode to emulator opcode using array lookup
	virtual EmuOpcode EQToEmu(const uint16 eq_op);
	
	// Set individual opcode mapping, updating both translation arrays
	virtual void SetOpcode(EmuOpcode emu_op, uint16 eq_op);
	
protected:
	// Strategy for storing opcodes in regular memory arrays
	class NormalMemStrategy : public OpcodeManager::OpcodeSetStrategy
	{
	public:
		RegularOpcodeManager *it;	// Pointer to parent manager
		
		// Store opcode mapping in memory arrays
		void Set(EmuOpcode emu_op, uint16 eq_op);
	};
	friend class NormalMemStrategy;
	
private:
	uint16 *emu_to_eq;			// Array mapping emulator opcodes to EverQuest opcodes
	EmuOpcode *eq_to_emu;		// Array mapping EverQuest opcodes to emulator opcodes
	uint32 EQOpcodeCount;		// Size of EverQuest opcode array
	uint32 EmuOpcodeCount;		// Size of emulator opcode array
};

// Null opcode manager that always returns default values (for testing)
class NullOpcodeManager : public MutableOpcodeManager
{
public:
	NullOpcodeManager();
	
	// Always succeeds but loads no actual opcodes
	virtual bool LoadOpcodes(const char *filename);
	
	// Always succeeds but loads no actual opcodes
	virtual bool LoadOpcodes(map<string, uint16>* eq, std::string* missingOpcodes = nullptr);
	
	// Always succeeds but reloads no actual opcodes
	virtual bool ReloadOpcodes(const char *filename);
	
	// Always returns 0 (invalid opcode)
	virtual uint16 EmuToEQ(const EmuOpcode emu_op);
	
	// Always returns OP_Unknown
	virtual EmuOpcode EQToEmu(const uint16 eq_op);
	
	// No-op implementation for testing compatibility
	virtual void SetOpcode(EmuOpcode emu_op, uint16 eq_op) {}
};

// Empty opcode manager that starts with no mappings but remembers what is set
class EmptyOpcodeManager : public MutableOpcodeManager
{
public:
	EmptyOpcodeManager();
	
	// No-op load operation - manager starts empty
	virtual bool LoadOpcodes(const char *filename);
	
	// No-op load operation - manager starts empty
	virtual bool LoadOpcodes(map<string, uint16>* eq, std::string* missingOpcodes = nullptr);
	
	// No-op reload operation
	virtual bool ReloadOpcodes(const char *filename);
	
	// Lookup emulator to EverQuest opcode in stored mappings
	virtual uint16 EmuToEQ(const EmuOpcode emu_op);
	
	// Lookup EverQuest to emulator opcode in stored mappings
	virtual EmuOpcode EQToEmu(const uint16 eq_op);
	
	// Store opcode mapping in internal maps
	virtual void SetOpcode(EmuOpcode emu_op, uint16 eq_op);

private:
	map<EmuOpcode, uint16> emu_to_eq;		// Map of emulator to EverQuest opcodes
	map<uint16, EmuOpcode> eq_to_emu;		// Map of EverQuest to emulator opcodes
};

// Implementation

// Initialize opcode manager in unloaded state
OpcodeManager::OpcodeManager()
{
	loaded = false;
}

// Load opcodes from map using specified storage strategy
bool OpcodeManager::LoadOpcodesMap(map<string, uint16>* eq, OpcodeSetStrategy *s, std::string* missingOpcodes)
{
	bool ret = true;
	EmuOpcode emu_op;
	map<string, uint16>::iterator res;

	// Iterate through all emulator opcodes to build translation mappings
	for(emu_op = (EmuOpcode)(0); emu_op < _maxEmuOpcode; emu_op=(EmuOpcode)(emu_op+1)) {
		// Get human-readable name for this emulator opcode
		const char *op_name = OpcodeNames[emu_op];
		if(op_name[0] == '\0') {
			break;
		}
		
		// Find corresponding EverQuest opcode in the provided map
		res = eq->find(op_name);
		if(res == eq->end()) {
			// Handle missing opcode by either logging or collecting for batch report
			if(missingOpcodes) {
				if(missingOpcodes->size() < 1) {
					missingOpcodes->append(op_name);
				}
				else {
					missingOpcodes->append(", " + std::string(op_name));
				}
			}
			else {
				LogWrite(OPCODE__WARNING, 1, "Opcode", "Opcode %s is missing from the opcodes table.", op_name);
			}
			// Set invalid mapping to indicate missing opcode
			s->Set(emu_op, 0xFFFF);
			continue;
		}
		
		// Store valid mapping using the provided strategy
		s->Set(emu_op, res->second);
	}
	return ret;
}

// Parse opcode file and load mappings using specified storage strategy
bool OpcodeManager::LoadOpcodesFile(const char *filename, OpcodeSetStrategy *s)
{
	FILE *opf = fopen(filename, "r");
	if(opf == NULL) {
		LogWrite(OPCODE__ERROR, 0, "Opcode", "Unable to open opcodes file '%s'. Thats bad.", filename);
		return false;
	}
	
	map<string, uint16> eq;
	
	// Parse the opcode file line by line
	char line[2048];
	int lineno = 0;
	uint16 curop;
	while(!feof(opf)) {
		lineno++;
		line[0] = '\0';
		if(fgets(line, sizeof(line), opf) == NULL)
			break;
		
		// Skip lines that don't start with OP_ (comments, blank lines, etc.)
		if(line[0] != 'O' || line[1] != 'P' || line[2] != '_')
			continue;
		
		char *num = line+3;
		// Find the equals sign separating name from value
		while(*num != '=' && *num != '\0') {
			num++;
		}
		// Ensure we found a proper assignment
		if(*num != '=') {
			LogWrite(OPCODE__ERROR, 0, "Opcode", "Malformed opcode line at %s:%d\n", filename, lineno);
			continue;
		}
		*num = '\0';	// Null terminate the opcode name
		num++;			// Point to the opcode value
		
		// Parse hexadecimal opcode value
		if(sscanf(num, "0x%hx", &curop) != 1) {
			LogWrite(OPCODE__ERROR, 0, "Opcode", "Malformed opcode at %s:%d\n", filename, lineno);
			continue;
		}
		
		// Store parsed opcode mapping in temporary map
		eq[line] = curop;
	}
	fclose(opf);
	return LoadOpcodesMap(&eq, s);
}

// Convert emulator opcode to human-readable name
const char *OpcodeManager::EmuToName(const EmuOpcode emu_op)
{
	if(emu_op > _maxEmuOpcode)
		return "OP_Unknown";
	
	return OpcodeNames[emu_op];
}

// Convert EverQuest opcode to human-readable name via emulator opcode lookup
const char *OpcodeManager::EQToName(const uint16 eq_op)
{
	// First resolve EverQuest opcode to emulator opcode
	EmuOpcode emu_op = EQToEmu(eq_op);
	if(emu_op > _maxEmuOpcode)
		return "OP_Unknown";
	
	return OpcodeNames[emu_op];
}

// Search for emulator opcode by name (case-insensitive)
EmuOpcode OpcodeManager::NameSearch(const char *name)
{
	EmuOpcode emu_op;
	// Linear search through all opcode names
	for(emu_op = (EmuOpcode)(0); emu_op < _maxEmuOpcode; emu_op=(EmuOpcode)(emu_op+1)) {
		const char *op_name = OpcodeNames[emu_op];
		if(!strcasecmp(op_name, name)) {
			return emu_op;
		}
	}
	return OP_Unknown;
}

// Initialize regular opcode manager with null arrays
RegularOpcodeManager::RegularOpcodeManager()
: MutableOpcodeManager()
{
	emu_to_eq = nullptr;
	eq_to_emu = nullptr;
	EQOpcodeCount = 0;
	EmuOpcodeCount = 0;
}

// Clean up allocated translation arrays
RegularOpcodeManager::~RegularOpcodeManager()
{
	delete[] emu_to_eq;
	delete[] eq_to_emu;
}

// Load opcodes from map into memory arrays
bool RegularOpcodeManager::LoadOpcodes(map<string, uint16>* eq, std::string* missingOpcodes)
{
	NormalMemStrategy s;
	s.it = this;
	std::lock_guard<std::mutex> lock(MOpcodes);
	
	loaded = true;
	eq_to_emu = new EmuOpcode[MAX_EQ_OPCODE];
	emu_to_eq = new uint16[_maxEmuOpcode];
	EQOpcodeCount = MAX_EQ_OPCODE;
	EmuOpcodeCount = _maxEmuOpcode;
	
	// Initialize arrays with default values
	memset(eq_to_emu, 0, sizeof(EmuOpcode)*MAX_EQ_OPCODE);
	memset(emu_to_eq, 0xCD, sizeof(uint16)*_maxEmuOpcode);
	
	bool ret = LoadOpcodesMap(eq, &s, missingOpcodes);
	return ret;
}

// Load opcodes from file into memory arrays
bool RegularOpcodeManager::LoadOpcodes(const char *filename)
{
	NormalMemStrategy s;
	s.it = this;
	std::lock_guard<std::mutex> lock(MOpcodes);
	
	loaded = true;
	eq_to_emu = new EmuOpcode[MAX_EQ_OPCODE];
	emu_to_eq = new uint16[_maxEmuOpcode];
	EQOpcodeCount = MAX_EQ_OPCODE;
	EmuOpcodeCount = _maxEmuOpcode;
	
	// Initialize arrays with default values
	memset(eq_to_emu, 0, sizeof(EmuOpcode)*MAX_EQ_OPCODE);
	memset(emu_to_eq, 0xCD, sizeof(uint16)*_maxEmuOpcode);
	
	bool ret = LoadOpcodesFile(filename, &s);
	return ret;
}

// Reload opcodes from file, preserving existing array allocations
bool RegularOpcodeManager::ReloadOpcodes(const char *filename)
{
	if(!loaded)
		return LoadOpcodes(filename);
	
	NormalMemStrategy s;
	s.it = this;
	std::lock_guard<std::mutex> lock(MOpcodes);
	
	// Clear existing EverQuest to emulator mappings
	memset(eq_to_emu, 0, sizeof(EmuOpcode)*MAX_EQ_OPCODE);
	
	bool ret = LoadOpcodesFile(filename, &s);
	return ret;
}

// Convert emulator opcode to EverQuest opcode using array lookup
uint16 RegularOpcodeManager::EmuToEQ(const EmuOpcode emu_op)
{
	uint16 res;
	std::lock_guard<std::mutex> lock(MOpcodes);
	
	if(emu_op > _maxEmuOpcode)
		res = 0;
	else
		res = emu_to_eq[emu_op];
	
	return res;
}

// Convert EverQuest opcode to emulator opcode using array lookup
EmuOpcode RegularOpcodeManager::EQToEmu(const uint16 eq_op)
{
	EmuOpcode res;
	std::lock_guard<std::mutex> lock(MOpcodes);
	
	if(eq_op >= MAX_EQ_OPCODE)
		res = OP_Unknown;
	else
		res = eq_to_emu[eq_op];
	
	return res;
}

// Set individual opcode mapping, updating both translation arrays
void RegularOpcodeManager::SetOpcode(EmuOpcode emu_op, uint16 eq_op)
{
	// Clear existing mapping for this emulator opcode
	uint16 oldop = 0;
	
	if(emu_op <= _maxEmuOpcode)
		oldop = emu_to_eq[emu_op];
	
	if(oldop != 0 && oldop < MAX_EQ_OPCODE)
		eq_to_emu[oldop] = OP_Unknown;
	
	// Set new mapping using our strategy
	NormalMemStrategy s;
	s.it = this;
	s.Set(emu_op, eq_op);
}

// Store opcode mapping in memory arrays
void RegularOpcodeManager::NormalMemStrategy::Set(EmuOpcode emu_op, uint16 eq_op)
{
	if(uint32(emu_op) >= it->EmuOpcodeCount || eq_op >= it->EQOpcodeCount)
		return;
	it->emu_to_eq[emu_op] = eq_op;
	it->eq_to_emu[eq_op] = emu_op;
}

// Initialize null opcode manager
NullOpcodeManager::NullOpcodeManager()
: MutableOpcodeManager()
{
}

// No-op load from map - always succeeds but loads nothing
bool NullOpcodeManager::LoadOpcodes(map<string, uint16>* eq, std::string* missingOpcodes)
{
	return true;
}

// No-op load from file - always succeeds but loads nothing
bool NullOpcodeManager::LoadOpcodes(const char *filename)
{
	return true;
}

// No-op reload - always succeeds but reloads nothing
bool NullOpcodeManager::ReloadOpcodes(const char *filename)
{
	return true;
}

// Always return invalid opcode
uint16 NullOpcodeManager::EmuToEQ(const EmuOpcode emu_op)
{
	return 0;
}

// Always return unknown opcode
EmuOpcode NullOpcodeManager::EQToEmu(const uint16 eq_op)
{
	return OP_Unknown;
}

// Initialize empty opcode manager
EmptyOpcodeManager::EmptyOpcodeManager()
: MutableOpcodeManager()
{
}

// No-op load from file - manager starts empty
bool EmptyOpcodeManager::LoadOpcodes(const char *filename)
{
	return true;
}

// No-op load from map - manager starts empty
bool EmptyOpcodeManager::LoadOpcodes(map<string, uint16>* eq, std::string* missingOpcodes)
{
	return true;
}

// No-op reload operation
bool EmptyOpcodeManager::ReloadOpcodes(const char *filename)
{
	return true;
}

// Lookup emulator to EverQuest opcode in stored mappings
uint16 EmptyOpcodeManager::EmuToEQ(const EmuOpcode emu_op)
{
	map<EmuOpcode, uint16>::iterator f;
	f = emu_to_eq.find(emu_op);
	return (f == emu_to_eq.end() ? 0 : f->second);
}

// Lookup EverQuest to emulator opcode in stored mappings
EmuOpcode EmptyOpcodeManager::EQToEmu(const uint16 eq_op)
{
	map<uint16, EmuOpcode>::iterator f;
	f = eq_to_emu.find(eq_op);
	return (f == eq_to_emu.end() ? OP_Unknown : f->second);
}

// Store opcode mapping in internal maps
void EmptyOpcodeManager::SetOpcode(EmuOpcode emu_op, uint16 eq_op)
{
	emu_to_eq[emu_op] = eq_op;
	eq_to_emu[eq_op] = emu_op;
}