// Copyright 2015 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#pragma once

#include <array>
#include <bitset>
#include <cstddef>
#include <memory>
#include <random>
#include <string>
#include <vector>
#include <boost/container/static_vector.hpp>
#include "common/bit_field.h"
#include "common/common_types.h"
#include "core/hle/kernel/handle_table.h"
#include "core/hle/kernel/object.h"
#include "core/hle/kernel/thread.h"
#include "core/hle/kernel/vm_manager.h"

namespace FileSys {
class ProgramMetadata;
}

namespace Kernel {

class KernelCore;
class ResourceLimit;

struct AddressMapping {
    // Address and size must be page-aligned
    VAddr address;
    u64 size;
    bool read_only;
    bool unk_flag;
};

enum class MemoryRegion : u16 {
    APPLICATION = 1,
    SYSTEM = 2,
    BASE = 3,
};

union ProcessFlags {
    u16 raw;

    BitField<0, 1, u16>
        allow_debug; ///< Allows other processes to attach to and debug this process.
    BitField<1, 1, u16> force_debug; ///< Allows this process to attach to processes even if they
                                     /// don't have allow_debug set.
    BitField<2, 1, u16> allow_nonalphanum;
    BitField<3, 1, u16> shared_page_writable; ///< Shared page is mapped with write permissions.
    BitField<4, 1, u16> privileged_priority;  ///< Can use priority levels higher than 24.
    BitField<5, 1, u16> allow_main_args;
    BitField<6, 1, u16> shared_device_mem;
    BitField<7, 1, u16> runnable_on_sleep;
    BitField<8, 4, MemoryRegion>
        memory_region;                ///< Default region for memory allocations for this process
    BitField<12, 1, u16> loaded_high; ///< Application loaded high (not at 0x00100000).
};

/**
 * Indicates the status of a Process instance.
 *
 * @note These match the values as used by kernel,
 *       so new entries should only be added if RE
 *       shows that a new value has been introduced.
 */
enum class ProcessStatus {
    Created,
    CreatedWithDebuggerAttached,
    Running,
    WaitingForDebuggerToAttach,
    DebuggerAttached,
    Exiting,
    Exited,
    DebugBreak,
};

struct CodeSet final {
    struct Segment {
        std::size_t offset = 0;
        VAddr addr = 0;
        u32 size = 0;
    };

    explicit CodeSet();
    ~CodeSet();

    Segment& CodeSegment() {
        return segments[0];
    }

    const Segment& CodeSegment() const {
        return segments[0];
    }

    Segment& RODataSegment() {
        return segments[1];
    }

    const Segment& RODataSegment() const {
        return segments[1];
    }

    Segment& DataSegment() {
        return segments[2];
    }

    const Segment& DataSegment() const {
        return segments[2];
    }

    std::shared_ptr<std::vector<u8>> memory;

    std::array<Segment, 3> segments;
    VAddr entrypoint = 0;
};

class Process final : public Object {
public:
    static constexpr std::size_t RANDOM_ENTROPY_SIZE = 4;

    static SharedPtr<Process> Create(KernelCore& kernel, std::string&& name);

    std::string GetTypeName() const override {
        return "Process";
    }
    std::string GetName() const override {
        return name;
    }

    static const HandleType HANDLE_TYPE = HandleType::Process;
    HandleType GetHandleType() const override {
        return HANDLE_TYPE;
    }

    /// Gets a reference to the process' memory manager.
    Kernel::VMManager& VMManager() {
        return vm_manager;
    }

    /// Gets a const reference to the process' memory manager.
    const Kernel::VMManager& VMManager() const {
        return vm_manager;
    }

    /// Gets a reference to the process' handle table.
    HandleTable& GetHandleTable() {
        return handle_table;
    }

    /// Gets a const reference to the process' handle table.
    const HandleTable& GetHandleTable() const {
        return handle_table;
    }

    /// Gets the current status of the process
    ProcessStatus GetStatus() const {
        return status;
    }

    /// Gets the unique ID that identifies this particular process.
    u32 GetProcessID() const {
        return process_id;
    }

    /// Gets the title ID corresponding to this process.
    u64 GetTitleID() const {
        return program_id;
    }

    /// Gets the resource limit descriptor for this process
    ResourceLimit& GetResourceLimit() {
        return *resource_limit;
    }

    /// Gets the resource limit descriptor for this process
    const ResourceLimit& GetResourceLimit() const {
        return *resource_limit;
    }

    /// Gets the default CPU ID for this process
    u8 GetDefaultProcessorID() const {
        return ideal_processor;
    }

    /// Gets the bitmask of allowed CPUs that this process' threads can run on.
    u32 GetAllowedProcessorMask() const {
        return allowed_processor_mask;
    }

    /// Gets the bitmask of allowed thread priorities.
    u32 GetAllowedThreadPriorityMask() const {
        return allowed_thread_priority_mask;
    }

    u32 IsVirtualMemoryEnabled() const {
        return is_virtual_address_memory_enabled;
    }

    /// Whether this process is an AArch64 or AArch32 process.
    bool Is64BitProcess() const {
        return is_64bit_process;
    }

    /// Gets the total running time of the process instance in ticks.
    u64 GetCPUTimeTicks() const {
        return total_process_running_time_ticks;
    }

    /// Updates the total running time, adding the given ticks to it.
    void UpdateCPUTimeTicks(u64 ticks) {
        total_process_running_time_ticks += ticks;
    }

    /// Gets 8 bytes of random data for svcGetInfo RandomEntropy
    u64 GetRandomEntropy(std::size_t index) const {
        return random_entropy.at(index);
    }

    /**
     * Loads process-specifics configuration info with metadata provided
     * by an executable.
     *
     * @param metadata The provided metadata to load process specific info.
     */
    void LoadFromMetadata(const FileSys::ProgramMetadata& metadata);

    /**
     * Parses a list of kernel capability descriptors (as found in the ExHeader) and applies them
     * to this process.
     */
    void ParseKernelCaps(const u32* kernel_caps, std::size_t len);

    /**
     * Applies address space changes and launches the process main thread.
     */
    void Run(VAddr entry_point, s32 main_thread_priority, u32 stack_size);

    /**
     * Prepares a process for termination by stopping all of its threads
     * and clearing any other resources.
     */
    void PrepareForTermination();

    void LoadModule(CodeSet module_, VAddr base_addr);

    ///////////////////////////////////////////////////////////////////////////////////////////////
    // Memory Management

    // Marks the next available region as used and returns the address of the slot.
    VAddr MarkNextAvailableTLSSlotAsUsed(Thread& thread);

    // Frees a used TLS slot identified by the given address
    void FreeTLSSlot(VAddr tls_address);

    ResultVal<VAddr> HeapAllocate(VAddr target, u64 size, VMAPermission perms);
    ResultCode HeapFree(VAddr target, u32 size);

    ResultCode MirrorMemory(VAddr dst_addr, VAddr src_addr, u64 size);

    ResultCode UnmapMemory(VAddr dst_addr, VAddr src_addr, u64 size);

private:
    explicit Process(KernelCore& kernel);
    ~Process() override;

    /// Memory manager for this process.
    Kernel::VMManager vm_manager;

    /// Current status of the process
    ProcessStatus status;

    /// The ID of this process
    u32 process_id = 0;

    /// Title ID corresponding to the process
    u64 program_id;

    /// Resource limit descriptor for this process
    SharedPtr<ResourceLimit> resource_limit;

    /// The process may only call SVCs which have the corresponding bit set.
    std::bitset<0x80> svc_access_mask;
    /// Maximum size of the handle table for the process.
    u32 handle_table_size = 0x200;
    /// Special memory ranges mapped into this processes address space. This is used to give
    /// processes access to specific I/O regions and device memory.
    boost::container::static_vector<AddressMapping, 8> address_mappings;
    ProcessFlags flags;
    /// Kernel compatibility version for this process
    u16 kernel_version = 0;
    /// The default CPU for this process, threads are scheduled on this cpu by default.
    u8 ideal_processor = 0;
    /// Bitmask of allowed CPUs that this process' threads can run on. TODO(Subv): Actually parse
    /// this value from the process header.
    u32 allowed_processor_mask = THREADPROCESSORID_DEFAULT_MASK;
    u32 allowed_thread_priority_mask = 0xFFFFFFFF;
    u32 is_virtual_address_memory_enabled = 0;

    /// The Thread Local Storage area is allocated as processes create threads,
    /// each TLS area is 0x200 bytes, so one page (0x1000) is split up in 8 parts, and each part
    /// holds the TLS for a specific thread. This vector contains which parts are in use for each
    /// page as a bitmask.
    /// This vector will grow as more pages are allocated for new threads.
    std::vector<std::bitset<8>> tls_slots;

    /// Whether or not this process is AArch64, or AArch32.
    /// By default, we currently assume this is true, unless otherwise
    /// specified by metadata provided to the process during loading.
    bool is_64bit_process = true;

    /// Total running time for the process in ticks.
    u64 total_process_running_time_ticks = 0;

    /// Per-process handle table for storing created object handles in.
    HandleTable handle_table;

    /// Random values for svcGetInfo RandomEntropy
    std::array<u64, RANDOM_ENTROPY_SIZE> random_entropy;

    std::string name;
};

} // namespace Kernel
