/****************************************************************************
 * Copyright (C) 2018-2021 Maschell
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ****************************************************************************/

#include "ModuleDataFactory.h"
#include "../utils/FileUtils.h"
#include "ElfUtils.h"
#include "utils/OnLeavingScope.h"
#include "utils/utils.h"
#include "utils/wiiu_zlib.hpp"
#include <coreinit/cache.h>
#include <map>
#include <string>
#include <vector>

std::optional<std::unique_ptr<ModuleData>>
ModuleDataFactory::load(const std::string &path, uint32_t destination_address_end, uint32_t maximum_size, relocation_trampoline_entry_t *trampoline_data, uint32_t trampoline_data_length) {
    ELFIO::elfio reader(new wiiu_zlib);
    auto moduleData = make_unique_nothrow<ModuleData>();
    if (!moduleData) {
        DEBUG_FUNCTION_LINE_ERR("Failed to allocate ModuleData");
        return {};
    }

    uint8_t *buffer = nullptr;
    uint32_t fsize  = 0;
    if (LoadFileToMem(path.c_str(), &buffer, &fsize) < 0) {
        DEBUG_FUNCTION_LINE_ERR("Failed to load file");
        return {};
    }

    // Load ELF data
    if (!reader.load(reinterpret_cast<char *>(buffer), fsize)) {
        DEBUG_FUNCTION_LINE_ERR("Can't find or process %s", path.c_str());
        free(buffer);
        return {};
    }

    auto cleanupBuffer = onLeavingScope([buffer]() { free(buffer); });

    uint32_t sec_num = reader.sections.size();

    auto destinations = make_unique_nothrow<uint8_t *[]>(sec_num);
    if (!destinations) {
        DEBUG_FUNCTION_LINE_ERR("Failed alloc memory for destinations array");
        return {};
    }

    uint32_t sizeOfModule = 0;
    for (uint32_t i = 0; i < sec_num; ++i) {
        ELFIO::section *psec = reader.sections[i];
        if (psec->get_type() == 0x80000002) {
            continue;
        }

        if ((psec->get_type() == ELFIO::SHT_PROGBITS || psec->get_type() == ELFIO::SHT_NOBITS) && (psec->get_flags() & ELFIO::SHF_ALLOC)) {
            sizeOfModule += psec->get_size() + 1;
        }
    }

    if (sizeOfModule > maximum_size) {
        DEBUG_FUNCTION_LINE_ERR("Module is too big.");
        return {};
    }

    uint32_t baseOffset   = (destination_address_end - sizeOfModule) & 0xFFFFFF00;
    uint32_t startAddress = baseOffset;

    uint32_t offset_text = baseOffset;
    uint32_t offset_data = offset_text;

    uint32_t entrypoint = offset_text + (uint32_t) reader.get_entry() - 0x02000000;

    uint32_t totalSize  = 0;
    uint32_t endAddress = 0;

    for (uint32_t i = 0; i < sec_num; ++i) {
        ELFIO::section *psec = reader.sections[i];
        if (psec->get_type() == 0x80000002 || psec->get_name() == ".wut_load_bounds") {
            continue;
        }

        if ((psec->get_type() == ELFIO::SHT_PROGBITS || psec->get_type() == ELFIO::SHT_NOBITS) && (psec->get_flags() & ELFIO::SHF_ALLOC)) {
            uint32_t sectionSize = psec->get_size();

            totalSize += sectionSize;
            if (totalSize > maximum_size) {
                DEBUG_FUNCTION_LINE_ERR("Couldn't load setup module because it's too big.");
                return {};
            }

            auto address = (uint32_t) psec->get_address();

            destinations[psec->get_index()] = (uint8_t *) baseOffset;

            uint32_t destination = baseOffset + address;
            if ((address >= 0x02000000) && address < 0x10000000) {
                destination -= 0x02000000;
                destinations[psec->get_index()] -= 0x02000000;
                baseOffset += sectionSize;
                offset_data += sectionSize;
            } else if ((address >= 0x10000000) && address < 0xC0000000) {
                destination -= 0x10000000;
                destinations[psec->get_index()] -= 0x10000000;
            } else if (address >= 0xC0000000) {
                DEBUG_FUNCTION_LINE_ERR("Loading section from 0xC0000000 is NOT supported");
                return std::nullopt;
            } else {
                DEBUG_FUNCTION_LINE_ERR("Unhandled case");
                return std::nullopt;
            }

            const char *p = reader.sections[i]->get_data();

            if (destination + sectionSize > (uint32_t) destination_address_end) {
                DEBUG_FUNCTION_LINE_ERR("Tried to overflow buffer. %08X > %08X", destination + sectionSize, destination_address_end);
                OSFatal("EnvironmentLoader: Tried to overflow buffer");
            }

            if (psec->get_type() == ELFIO::SHT_NOBITS) {
                DEBUG_FUNCTION_LINE("memset section %s %08X to 0 (%d bytes)", psec->get_name().c_str(), destination, sectionSize);
                memset((void *) destination, 0, sectionSize);
            } else if (psec->get_type() == ELFIO::SHT_PROGBITS) {
                DEBUG_FUNCTION_LINE("Copy section %s %08X -> %08X (%d bytes)", psec->get_name().c_str(), p, destination, sectionSize);
                memcpy((void *) destination, p, sectionSize);
            }

            //nextAddress = ROUNDUP(destination + sectionSize, 0x100);
            if (psec->get_name() == ".bss" || psec->get_name() == ".sbss") {
                DEBUG_FUNCTION_LINE("memset %s section. Location: %08X size: %08X", psec->get_name().c_str(), destination, sectionSize);
                memset(reinterpret_cast<void *>(destination), 0, sectionSize);
            }

            if (endAddress < destination + sectionSize) {
                endAddress = destination + sectionSize;
            }

            DCFlushRange((void *) destination, sectionSize);
            ICInvalidateRange((void *) destination, sectionSize);
        }
    }

    for (uint32_t i = 0; i < sec_num; ++i) {
        ELFIO::section *psec = reader.sections[i];
        if ((psec->get_type() == ELFIO::SHT_PROGBITS || psec->get_type() == ELFIO::SHT_NOBITS) && (psec->get_flags() & ELFIO::SHF_ALLOC)) {
            DEBUG_FUNCTION_LINE("Linking (%d)... %s", i, psec->get_name().c_str());
            if (!linkSection(reader, psec->get_index(), (uint32_t) destinations[psec->get_index()], offset_text, offset_data, trampoline_data, trampoline_data_length)) {
                DEBUG_FUNCTION_LINE_ERR("elfLink failed");
                return std::nullopt;
            }
        }
    }
    getImportRelocationData(moduleData, reader, destinations.get());

    DCFlushRange((void *) baseOffset, totalSize);
    ICInvalidateRange((void *) baseOffset, totalSize);

    moduleData->setStartAddress(startAddress);
    moduleData->setEndAddress(endAddress);
    moduleData->setEntrypoint(entrypoint);
    DEBUG_FUNCTION_LINE("Saved entrypoint as %08X", entrypoint);

    return moduleData;
}

bool ModuleDataFactory::getImportRelocationData(std::unique_ptr<ModuleData> &moduleData, ELFIO::elfio &reader, uint8_t **destinations) {
    std::map<uint32_t, std::shared_ptr<ImportRPLInformation>> infoMap;

    uint32_t sec_num = reader.sections.size();

    for (uint32_t i = 0; i < sec_num; ++i) {
        auto *psec = reader.sections[i];
        if (psec->get_type() == 0x80000002) {
            auto info = make_shared_nothrow<ImportRPLInformation>(psec->get_name());
            if (!info) {
                DEBUG_FUNCTION_LINE_ERR("Failed too allocate ImportRPLInformation");
                return false;
            }
            infoMap[i] = std::move(info);
        }
    }

    for (uint32_t i = 0; i < sec_num; ++i) {
        ELFIO::section *psec = reader.sections[i];
        if (psec->get_type() == ELFIO::SHT_RELA || psec->get_type() == ELFIO::SHT_REL) {
            ELFIO::relocation_section_accessor rel(reader, psec);
            for (uint32_t j = 0; j < (uint32_t) rel.get_entries_num(); ++j) {
                ELFIO::Elf_Word symbol = 0;
                ELFIO::Elf64_Addr offset;
                ELFIO::Elf_Word type;
                ELFIO::Elf_Sxword addend;
                std::string sym_name;
                ELFIO::Elf64_Addr sym_value;

                if (!rel.get_entry(j, offset, symbol, type, addend)) {
                    DEBUG_FUNCTION_LINE_ERR("Failed to get relocation");
                    return false;
                }
                ELFIO::symbol_section_accessor symbols(reader, reader.sections[(ELFIO::Elf_Half) psec->get_link()]);

                // Find the symbol
                ELFIO::Elf_Xword size;
                unsigned char bind;
                unsigned char symbolType;
                ELFIO::Elf_Half sym_section_index;
                unsigned char other;

                if (!symbols.get_symbol(symbol, sym_name, sym_value, size,
                                        bind, symbolType, sym_section_index, other)) {
                    DEBUG_FUNCTION_LINE_ERR("Failed to get symbol");
                    return false;
                }

                auto adjusted_sym_value = (uint32_t) sym_value;
                if (adjusted_sym_value < 0xC0000000) {
                    continue;
                }

                uint32_t section_index = psec->get_info();
                if (!infoMap.contains(sym_section_index)) {
                    DEBUG_FUNCTION_LINE_ERR("Relocation is referencing a unknown section. %d destination: %08X sym_name %s", section_index, destinations[section_index], sym_name.c_str());
                    OSFatal("Relocation is referencing a unknown section.");
                }

                auto relocationData = make_unique_nothrow<RelocationData>(type,
                                                                          offset - 0x02000000,
                                                                          addend,
                                                                          (void *) (destinations[section_index] + 0x02000000),
                                                                          sym_name,
                                                                          infoMap[sym_section_index]);

                if (!relocationData) {
                    DEBUG_FUNCTION_LINE_ERR("Failed to alloc relocation data");
                    return false;
                }

                moduleData->addRelocationData(std::move(relocationData));
            }
        }
    }
    return true;
}

bool ModuleDataFactory::linkSection(ELFIO::elfio &reader, uint32_t section_index, uint32_t destination, uint32_t base_text, uint32_t base_data, relocation_trampoline_entry_t *trampoline_data,
                                    uint32_t trampoline_data_length) {
    uint32_t sec_num = reader.sections.size();

    for (uint32_t i = 0; i < sec_num; ++i) {
        ELFIO::section *psec = reader.sections[i];
        if (psec->get_info() == section_index) {
            DEBUG_FUNCTION_LINE_VERBOSE("Found relocation section %s", psec->get_name().c_str());
            ELFIO::relocation_section_accessor rel(reader, psec);
            for (uint32_t j = 0; j < (uint32_t) rel.get_entries_num(); ++j) {
                ELFIO::Elf_Word symbol = 0;
                ELFIO::Elf64_Addr offset;
                ELFIO::Elf_Word type;
                ELFIO::Elf_Sxword addend;
                std::string sym_name;
                ELFIO::Elf64_Addr sym_value;

                if (!rel.get_entry(j, offset, symbol, type, addend)) {
                    DEBUG_FUNCTION_LINE_ERR("Failed to get relocation");
                    return false;
                }
                ELFIO::symbol_section_accessor symbols(reader, reader.sections[(ELFIO::Elf_Half) psec->get_link()]);

                // Find the symbol
                ELFIO::Elf_Xword size;
                unsigned char bind;
                unsigned char symbolType;
                ELFIO::Elf_Half sym_section_index;
                unsigned char other;

                if (!symbols.get_symbol(symbol, sym_name, sym_value, size,
                                        bind, symbolType, sym_section_index, other)) {
                    DEBUG_FUNCTION_LINE_ERR("Failed to get symbol");
                    return false;
                }

                auto adjusted_sym_value = (uint32_t) sym_value;
                if ((adjusted_sym_value >= 0x02000000) && adjusted_sym_value < 0x10000000) {
                    adjusted_sym_value -= 0x02000000;
                    adjusted_sym_value += base_text;
                } else if ((adjusted_sym_value >= 0x10000000) && adjusted_sym_value < 0xC0000000) {
                    adjusted_sym_value -= 0x10000000;
                    adjusted_sym_value += base_data;
                } else if (adjusted_sym_value >= 0xC0000000) {
                    // Skip imports
                    continue;
                } else if (adjusted_sym_value == 0x0) {
                    //
                } else {
                    DEBUG_FUNCTION_LINE_ERR("Unhandled case %08X", adjusted_sym_value);
                    return false;
                }

                if (sym_section_index == ELFIO::SHN_ABS) {
                    //
                } else if (sym_section_index > ELFIO::SHN_LORESERVE) {
                    DEBUG_FUNCTION_LINE_ERR("NOT IMPLEMENTED: %04X", sym_section_index);
                    return false;
                }
                if (!ElfUtils::elfLinkOne(type, offset, addend, destination, adjusted_sym_value, trampoline_data, trampoline_data_length, RELOC_TYPE_FIXED)) {
                    DEBUG_FUNCTION_LINE_ERR("Link failed");
                    return false;
                }
            }
        }
    }
    return true;
}