//
// Created by selim on 27.11.22.
//

#include "Reader.h"
#include "elfio/elfio_dump.hpp"
#include "elfio/elf_types.hpp"

#include <fstream>

namespace Dart {

    Reader::Reader(const fs::path& path) {
        if(!fs::exists(path)) {
            throw std::runtime_error("File does not exists");
        }

        if(!_elfio.load(path)) {
            throw std::runtime_error("Failed to load ELF file");
        }

        auto size = fs::file_size(path);
        _file = std::make_unique<std::byte[]>(size);

        std::ifstream stream(path, std::ios::binary);
        stream.read(reinterpret_cast<char*>(_file.get()), static_cast<std::streamsize>(size));

        if(stream.bad()) {
            throw std::runtime_error("Error reading ELF file");
        }
    }

    void Reader::dumpInfo() const {
        ELFIO::dump::header( std::cout, _elfio );
        ELFIO::dump::section_headers( std::cout, _elfio );
        ELFIO::dump::segment_headers( std::cout, _elfio );
        ELFIO::dump::symbol_tables( std::cout, _elfio );
        ELFIO::dump::notes( std::cout, _elfio );
        ELFIO::dump::modinfo( std::cout, _elfio );
        ELFIO::dump::dynamic_tags( std::cout, _elfio );
        ELFIO::dump::section_datas( std::cout, _elfio );
        ELFIO::dump::segment_datas( std::cout, _elfio );
    }

    const std::byte *Reader::getSnapshotPtr(DartSnapshot snapshot) const {
        auto snapshotName = getSnapshotName(snapshot);

        for(const auto& section: _elfio.sections) {
            const ELFIO::symbol_section_accessor symbols(_elfio, section.get());
            for(size_t i = 0; i < symbols.get_symbols_num(); ++i) {
                std::string name;
                ELFIO::Elf64_Addr address;
                ELFIO::Elf_Xword size;
                ELFIO::Elf_Half section_index;
                unsigned char bind, type, other;
                symbols.get_symbol(i, name, address, size, bind, type, section_index, other );

                if(name == snapshotName) {
                    return _file.get() + address;
                }
            }
        }

        return nullptr;
    }

    std::string Reader::getSnapshotName(DartSnapshot snapshot) {
        switch (snapshot) {
            case DartSnapshot::VM_INSTRUCTIONS: return "_kDartVmSnapshotInstructions";
            case DartSnapshot::VM_DATA: return "_kDartVmSnapshotData";
            case DartSnapshot::ISOLATE_INSTRUCTIONS: return "_kDartIsolateSnapshotInstructions";
            case DartSnapshot::ISOLATE_DATA: return "_kDartIsolateSnapshotData";
            case DartSnapshot::BUILD_ID: return "_kDartSnapshotBuildId";
        }

        return "";
    }

    Snapshot Reader::getSnapshot(DartSnapshot snapshot) const {
        auto ptr = getSnapshotPtr(snapshot);
        return Snapshot(ptr);
    }

}