//===---------------------ProcessStructReader.h ------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef utility_ProcessStructReader_h_
#define utility_ProcessStructReader_h_

#include "lldb/lldb-defines.h"
#include "lldb/lldb-types.h"

#include "lldb/Core/ConstString.h"
#include "lldb/Core/DataExtractor.h"
#include "lldb/Core/Error.h"
#include "lldb/Symbol/CompilerType.h"
#include "lldb/Target/Process.h"

#include <initializer_list>
#include <map>
#include <string>

namespace lldb_private {
    class ProcessStructReader
    {
    protected:
        struct FieldImpl
        {
            CompilerType type;
            size_t offset;
            size_t size;
        };
        
        std::map<ConstString, FieldImpl> m_fields;
        DataExtractor m_data;
        lldb::ByteOrder m_byte_order;
        size_t m_addr_byte_size;
        
    public:
        ProcessStructReader (Process *process, lldb::addr_t base_addr, CompilerType struct_type)
        {
            if (!process)
                return;
            if (base_addr == 0 || base_addr == LLDB_INVALID_ADDRESS)
                return;
            m_byte_order = process->GetByteOrder();
            m_addr_byte_size = process->GetAddressByteSize();

            for (size_t idx = 0; idx < struct_type.GetNumFields(); idx++)
            {
                std::string name;
                uint64_t bit_offset;
                uint32_t bitfield_bit_size;
                bool is_bitfield;
                CompilerType field_type = struct_type.GetFieldAtIndex(idx,name,&bit_offset,&bitfield_bit_size,&is_bitfield);
                // no support for bitfields in here (yet)
                if (is_bitfield)
                    return;
                auto size = field_type.GetByteSize(nullptr);
                // no support for things larger than a uint64_t (yet)
                if (size > 8)
                    return;
                ConstString const_name = ConstString(name.c_str());
                size_t byte_index = static_cast<size_t>(bit_offset / 8);
                m_fields[const_name] = FieldImpl{field_type, byte_index, static_cast<size_t>(size)};
            }
            size_t total_size = struct_type.GetByteSize(nullptr);
            lldb::DataBufferSP buffer_sp(new DataBufferHeap(total_size,0));
            Error error;
            process->ReadMemoryFromInferior(base_addr,
                                            buffer_sp->GetBytes(),
                                            total_size,
                                            error);
            if (error.Fail())
                return;
            m_data = DataExtractor(buffer_sp,m_byte_order,m_addr_byte_size);
        }
        
        template<typename RetType>
        RetType
        GetField (ConstString name, RetType fail_value = RetType())
        {
            auto iter = m_fields.find(name), end = m_fields.end();
            if (iter == end)
                return fail_value;
            auto size = iter->second.size;
            if (sizeof(RetType) < size)
                return fail_value;
            lldb::offset_t offset = iter->second.offset;
            if (offset + size > m_data.GetByteSize())
                return fail_value;
            return (RetType)(m_data.GetMaxU64(&offset, size));
        }
    };
}

#endif // utility_ProcessStructReader_h_
