#pragma once
#include <array>
#include <bitset>
#include <filesystem>
#include <fstream>
#include <optional>
#include <vector>
#include "helpers.hpp"
#include "handles.hpp"
#include "loader/ncsd.hpp"
#include "services/shared_font.hpp"

namespace PhysicalAddrs {
	enum : u32 {
		VRAM = 0x18000000,
		VRAMEnd = VRAM + 0x005FFFFF,
		FCRAM = 0x20000000,
		FCRAMEnd = FCRAM + 0x07FFFFFF
	};
}

namespace VirtualAddrs {
	enum : u32 {
		ExecutableStart = 0x00100000,
		MaxExeSize = 0x03F00000,
		ExecutableEnd = 0x00100000 + 0x03F00000,

		// Stack for main ARM11 thread.
		// Typically 0x4000 bytes, determined by exheader
		StackTop = 0x10000000,
		StackBottom = 0x0FFFC000,
		DefaultStackSize = 0x4000,

		NormalHeapStart = 0x08000000,
		LinearHeapStartOld = 0x14000000, // If kernel version < 0x22C
		LinearHeapStartNew = 0x30000000,

		// Start of TLS for first thread. Next thread's storage will be at TLSBase + 0x1000, and so on
		TLSBase = 0xFF400000,
		TLSSize = 0x1000,

		VramStart = 0x1F000000,
		VramSize = 0x00600000,
		FcramTotalSize = 128_MB,
		DSPMemStart = 0x1FF00000
	};
}

// Types for svcQueryMemory
namespace KernelMemoryTypes {
	// This makes no sense
	enum MemoryState : u32 {
		Free = 0,
		Reserved = 1,
		IO = 2,
		Static = 3,
		Code = 4,
		Private = 5,
		Shared = 6,
		Continuous = 7,
		Aliased = 8,
		Alias = 9,
		AliasCode = 10,
		Locked = 11,

		PERMISSION_R = 1 << 0,
		PERMISSION_W = 1 << 1,
		PERMISSION_X = 1 << 2
	};
	
	// I assume this is referring to a single piece of allocated memory? If it's for pages, it makes no sense.
	// If it's for multiple allocations, it also makes no sense
	struct MemoryInfo {
		u32 baseAddr; // Base process virtual address. Used as a paddr in lockedMemoryInfo instead
		u32 size;      // Of what?
		u32 perms;     // Is this referring to a single page or?
		u32 state;

		u32 end() { return baseAddr + size; }
		MemoryInfo(u32 baseAddr, u32 size, u32 perms, u32 state) : baseAddr(baseAddr), size(size)
			, perms(perms), state(state) {}
	};

	// Shared memory block for HID, GSP:GPU etc
	struct SharedMemoryBlock {
		u32 paddr; // Physical address of this block's memory
		u32 size; // Size of block
		u32 handle; // The handle of the shared memory block
		bool mapped; // Has this block been mapped at least once?

		SharedMemoryBlock(u32 paddr, u32 size, u32 handle) : paddr(paddr), size(size), handle(handle), mapped(false) {}
	};
}

class Memory {
	u8* fcram;
	u8* dspRam;

	u64& cpuTicks; // Reference to the CPU tick counter
	using SharedMemoryBlock = KernelMemoryTypes::SharedMemoryBlock;

	// Our dynarmic core uses page tables for reads and writes with 4096 byte pages
	std::vector<uintptr_t> readTable, writeTable;

	// This tracks our OS' memory allocations
	std::vector<KernelMemoryTypes::MemoryInfo> memoryInfo;

	std::array<SharedMemoryBlock, 3> sharedMemBlocks = {
		SharedMemoryBlock(0, _shared_font_len, KernelHandles::FontSharedMemHandle), // Shared memory for the system font
		SharedMemoryBlock(0, 0x1000, KernelHandles::GSPSharedMemHandle), // GSP shared memory
		SharedMemoryBlock(0, 0x1000, KernelHandles::HIDSharedMemHandle)  // HID shared memory
 	};

public:
	static constexpr u32 pageShift = 12;
	static constexpr u32 pageSize = 1 << pageShift;
	static constexpr u32 pageMask = pageSize - 1;
	static constexpr u32 totalPageCount = 1 << (32 - pageShift);
	
	static constexpr u32 FCRAM_SIZE = 128_MB;
	static constexpr u32 FCRAM_APPLICATION_SIZE = 64_MB;
	static constexpr u32 FCRAM_PAGE_COUNT = FCRAM_SIZE / pageSize;
	static constexpr u32 FCRAM_APPLICATION_PAGE_COUNT = FCRAM_APPLICATION_SIZE / pageSize;

	static constexpr u32 DSP_RAM_SIZE = 512_KB;
	static constexpr u32 DSP_CODE_MEMORY_OFFSET = 0_KB;
	static constexpr u32 DSP_DATA_MEMORY_OFFSET = 256_KB;

private:
	std::bitset<FCRAM_PAGE_COUNT> usedFCRAMPages;
	std::optional<u32> findPaddr(u32 size);
	u64 timeSince3DSEpoch();

	// https://www.3dbrew.org/wiki/Configuration_Memory#ENVINFO
	// Report a retail unit without JTAG
	static constexpr u32 envInfo = 1;

public:
	u16 kernelVersion = 0;
	u32 usedUserMemory = 0_MB; // How much of the APPLICATION FCRAM range is used (allocated to the appcore)
	u32 usedSystemMemory = 0_MB; // Similar for the SYSTEM range (reserved for the syscore)

	Memory(u64& cpuTicks);
	void reset();
	void* getReadPointer(u32 address);
	void* getWritePointer(u32 address);
	std::optional<u32> loadELF(std::ifstream& file);
	std::optional<NCSD> loadNCSD(const std::filesystem::path& path);

	u8 read8(u32 vaddr);
	u16 read16(u32 vaddr);
	u32 read32(u32 vaddr);
	u64 read64(u32 vaddr);
	std::string readString(u32 vaddr, u32 maxCharacters);

	void write8(u32 vaddr, u8 value);
	void write16(u32 vaddr, u16 value);
	void write32(u32 vaddr, u32 value);
	void write64(u32 vaddr, u64 value);

	u32 getLinearHeapVaddr();
	u8* getFCRAM() { return fcram; }

	// Total amount of OS-only FCRAM available (Can vary depending on how much FCRAM the app requests via the cart exheader)
	u32 totalSysFCRAM() {
		return FCRAM_SIZE - FCRAM_APPLICATION_SIZE;
	}

	// Amount of OS-only FCRAM currently available
	u32 remainingSysFCRAM() {
		return totalSysFCRAM() - usedSystemMemory;
	}

	// Physical FCRAM index to the start of OS FCRAM
	// We allocate the first part of physical FCRAM for the application, and the rest to the OS. So the index for the OS = application ram size
	u32 sysFCRAMIndex() {
		return FCRAM_APPLICATION_SIZE;
	}

	enum class BatteryLevel {
		Empty = 0, AlmostEmpty, OneBar, TwoBars, ThreeBars, FourBars
	};
	u8 getBatteryState(bool adapterConnected, bool charging, BatteryLevel batteryLevel) {
		u8 value = static_cast<u8>(batteryLevel) << 2; // Bits 2:4 are the battery level from 0 to 5
		if (adapterConnected) value |= 1 << 0; // Bit 0 shows if the charger is connected
		if (charging) value |= 1 << 1; // Bit 1 shows if we're charging

		return value;
	}

	NCCH* getCXI() {
		if (loadedCXI.has_value()) {
			return &loadedCXI.value();
		} else {
			return nullptr;
		}
	}

	// Returns whether "addr" is aligned to a page (4096 byte) boundary
	static constexpr bool isAligned(u32 addr) {
		return (addr & pageMask) == 0;
	}

	// Allocate "size" bytes of RAM starting from FCRAM index "paddr" (We pick it ourself if paddr == 0)
	// And map them to virtual address "vaddr" (We also pick it ourself if vaddr == 0).
	// If the "linear" flag is on, the paddr pages must be adjacent in FCRAM
	// This function is for interacting with the *user* portion of FCRAM mainly. For OS RAM, we use other internal functions below
	// r, w, x: Permissions for the allocated memory
	// adjustAddrs: If it's true paddr == 0 or vaddr == 0 tell the allocator to pick its own addresses. Used for eg svc ControlMemory
	// isMap: Shows whether this is a reserve operation, that allocates memory and maps it to the addr space, or if it's a map operation,
	// which just maps memory from paddr to vaddr without hassle. The latter is useful for shared memory mapping, the "map" ControlMemory, op, etc
	// Returns the vaddr the FCRAM was mapped to or nullopt if allocation failed
	std::optional<u32> allocateMemory(u32 vaddr, u32 paddr, u32 size, bool linear, bool r = true, bool w = true, bool x = true,
		bool adjustsAddrs = false, bool isMap = false);
	KernelMemoryTypes::MemoryInfo queryMemory(u32 vaddr);

	// For internal use
	// Allocates a "size"-sized chunk of system FCRAM and returns the index of physical FCRAM used for the allocation
	// Used for allocating things like shared memory and the like
	u32 allocateSysMemory(u32 size);

	// Map a shared memory block to virtual address vaddr with permissions "myPerms"
	// The kernel has a second permission parameter in MapMemoryBlock but not sure what's used for
	// TODO: Find out
	// Returns a pointer to the FCRAM block used for the memory if allocation succeeded
	u8* mapSharedMemory(Handle handle, u32 vaddr, u32 myPerms, u32 otherPerms);

	// Mirrors the page mapping for "size" bytes starting from sourceAddress, to "size" bytes in destAddress
	// All of the above must be page-aligned.
	void mirrorMapping(u32 destAddress, u32 sourceAddress, u32 size);

	// Backup of the game's CXI partition info, if any
	std::optional<NCCH> loadedCXI = std::nullopt;
	// File handle for reading the loaded ncch
	IOFile CXIFile;

	u8* getDSPMem() { return dspRam; }
	u8* getDSPDataMem() { return &dspRam[DSP_DATA_MEMORY_OFFSET]; }
	u8* getDSPCodeMem() { return &dspRam[DSP_CODE_MEMORY_OFFSET]; }

	u32 getUsedUserMem() { return usedUserMemory; }
};