/* This file is part of the dynarmic project.
 * Copyright (c) 2016 MerryMage
 * This software may be used and distributed according to the terms of the GNU
 * General Public License version 2 or any later version.
 */

#include <deque>
#include <memory>

#include <fmt/format.h>

#ifdef DYNARMIC_USE_LLVM
#include <llvm-c/Disassembler.h>
#include <llvm-c/Target.h>
#endif

#include "backend_x64/block_of_code.h"
#include "backend_x64/emit_x64.h"
#include "backend_x64/jitstate.h"
#include "common/assert.h"
#include "common/common_types.h"
#include "common/scope_exit.h"
#include "dynarmic/dynarmic.h"
#include "frontend/ir/basic_block.h"
#include "frontend/ir/location_descriptor.h"
#include "frontend/translate/translate.h"
#include "ir_opt/passes.h"

namespace Dynarmic {

using namespace BackendX64;

struct Jit::Impl {
    Impl(Jit* jit, UserCallbacks callbacks)
            : block_of_code(callbacks, &GetCurrentBlock, this)
            , jit_state()
            , emitter(&block_of_code, callbacks, jit)
            , callbacks(callbacks)
            , jit_interface(jit)
    {}

    BlockOfCode block_of_code;
    JitState jit_state;
    EmitX64 emitter;
    const UserCallbacks callbacks;

    // Requests made during execution to invalidate the cache are queued up here.
    std::deque<Common::AddressRange> invalid_cache_ranges;
    bool invalidate_entire_cache = false;

    void Execute(size_t cycle_count) {
        block_of_code.RunCode(&jit_state, cycle_count);
    }

    std::string Disassemble(const IR::LocationDescriptor& descriptor) {
        auto block = GetBasicBlock(descriptor);
        std::string result = fmt::format("address: {}\nsize: {} bytes\n", block.entrypoint, block.size);

#ifdef DYNARMIC_USE_LLVM
        LLVMInitializeX86TargetInfo();
        LLVMInitializeX86TargetMC();
        LLVMInitializeX86Disassembler();
        LLVMDisasmContextRef llvm_ctx = LLVMCreateDisasm("x86_64", nullptr, 0, nullptr, nullptr);
        LLVMSetDisasmOptions(llvm_ctx, LLVMDisassembler_Option_AsmPrinterVariant);

        const u8* pos = static_cast<const u8*>(block.entrypoint);
        const u8* end = pos + block.size;
        size_t remaining = block.size;

        while (pos < end) {
            char buffer[80];
            size_t inst_size = LLVMDisasmInstruction(llvm_ctx, const_cast<u8*>(pos), remaining, (u64)pos, buffer, sizeof(buffer));
            ASSERT(inst_size);
            for (const u8* i = pos; i < pos + inst_size; i++)
                result += fmt::format("{:02x} ", *i);
            for (size_t i = inst_size; i < 10; i++)
                result += "   ";
            result += buffer;
            result += '\n';

            pos += inst_size;
            remaining -= inst_size;
        }

        LLVMDisasmDispose(llvm_ctx);
#else
        result.append("(recompile with DYNARMIC_USE_LLVM=ON to disassemble the generated x86_64 code)\n");
#endif

        return result;
    }

    void PerformCacheInvalidation() {
        if (invalidate_entire_cache) {
            jit_state.ResetRSB();
            block_of_code.ClearCache();
            emitter.ClearCache();

            invalid_cache_ranges.clear();
            invalidate_entire_cache = false;
            return;
        }

        if (invalid_cache_ranges.empty()) {
            return;
        }

        jit_state.ResetRSB();
        while (!invalid_cache_ranges.empty()) {
            emitter.InvalidateCacheRange(invalid_cache_ranges.front());
            invalid_cache_ranges.pop_front();
        }
    }

    void RequestCacheInvalidation() {
        if (jit_interface->is_executing) {
            jit_state.halt_requested = true;
            return;
        }

        PerformCacheInvalidation();
    }

private:
    Jit* jit_interface;

    static CodePtr GetCurrentBlock(void *this_voidptr) {
        Jit::Impl& this_ = *reinterpret_cast<Jit::Impl*>(this_voidptr);
        JitState& jit_state = this_.jit_state;

        u32 pc = jit_state.Reg[15];
        Arm::PSR cpsr{jit_state.Cpsr};
        Arm::FPSCR fpscr{jit_state.FPSCR_mode};
        IR::LocationDescriptor descriptor{pc, cpsr, fpscr};

        return this_.GetBasicBlock(descriptor).entrypoint;
    }

    EmitX64::BlockDescriptor GetBasicBlock(IR::LocationDescriptor descriptor) {
        auto block = emitter.GetBasicBlock(descriptor);
        if (block)
            return *block;

        constexpr size_t MINIMUM_REMAINING_CODESIZE = 1 * 1024 * 1024;
        if (block_of_code.SpaceRemaining() < MINIMUM_REMAINING_CODESIZE) {
            invalidate_entire_cache = true;
            PerformCacheInvalidation();
        }

        IR::Block ir_block = Arm::Translate(descriptor, callbacks.memory.ReadCode);
        Optimization::GetSetElimination(ir_block);
        Optimization::DeadCodeElimination(ir_block);
        Optimization::ConstantPropagation(ir_block, callbacks.memory);
        Optimization::DeadCodeElimination(ir_block);
        Optimization::VerificationPass(ir_block);
        return emitter.Emit(ir_block);
    }
};

Jit::Jit(UserCallbacks callbacks) : impl(std::make_unique<Impl>(this, callbacks)) {}

Jit::~Jit() {}

void Jit::Run(size_t cycle_count) {
    ASSERT(!is_executing);
    is_executing = true;
    SCOPE_EXIT({ this->is_executing = false; });

    impl->jit_state.halt_requested = false;

    impl->Execute(cycle_count);

    impl->PerformCacheInvalidation();
}

void Jit::ClearCache() {
    impl->invalidate_entire_cache = true;
    impl->RequestCacheInvalidation();
}

void Jit::InvalidateCacheRange(std::uint32_t start_address, std::size_t length) {
    impl->invalid_cache_ranges.emplace_back(Common::AddressRange{start_address, length});
    impl->RequestCacheInvalidation();
}

void Jit::Reset() {
    ASSERT(!is_executing);
    impl->jit_state = {};
}

void Jit::HaltExecution() {
    impl->jit_state.halt_requested = true;
}

std::array<u32, 16>& Jit::Regs() {
    return impl->jit_state.Reg;
}
const std::array<u32, 16>& Jit::Regs() const {
    return impl->jit_state.Reg;
}

std::array<u32, 64>& Jit::ExtRegs() {
    return impl->jit_state.ExtReg;
}

const std::array<u32, 64>& Jit::ExtRegs() const {
    return impl->jit_state.ExtReg;
}

u32& Jit::Cpsr() {
    return impl->jit_state.Cpsr;
}

u32 Jit::Cpsr() const {
    return impl->jit_state.Cpsr;
}

u32 Jit::Fpscr() const {
    return impl->jit_state.Fpscr();
}

void Jit::SetFpscr(u32 value) const {
    return impl->jit_state.SetFpscr(value);
}

std::string Jit::Disassemble(const IR::LocationDescriptor& descriptor) {
    return impl->Disassemble(descriptor);
}

} // namespace Dynarmic