
#include "pickle.h"

#include <limits>

// static
const int Pickle::kPayloadUnit = 64;

// 特殊的capacity_标记只读对象.
static const size_t kCapacityReadOnly = std::numeric_limits<size_t>::max();

// Payload是uint32对齐.

Pickle::Pickle() : header_(NULL), header_size_(sizeof(Header)),
capacity_(0), variable_buffer_offset_(0)
{
    Resize(kPayloadUnit);
    header_->payload_size = 0;
}

Pickle::Pickle(int header_size) : header_(NULL),
header_size_(AlignInt(header_size, sizeof(uint32))),
capacity_(0), variable_buffer_offset_(0)
{
    DCHECK(static_cast<size_t>(header_size) >= sizeof(Header));
    DCHECK(header_size <= kPayloadUnit);
    Resize(kPayloadUnit);
    header_->payload_size = 0;
}

Pickle::Pickle(const char* data, int data_len)
: header_(reinterpret_cast<Header*>(const_cast<char*>(data))),
header_size_(data_len - header_->payload_size),
capacity_(kCapacityReadOnly), variable_buffer_offset_(0)
{
    if(data_len >= static_cast<int>(sizeof(Header)))
    {
        header_size_ = data_len - header_->payload_size;
    }

    if(header_size_ > static_cast<unsigned int>(data_len))
    {
        header_size_ = 0;
    }

    if(header_size_ != AlignInt(header_size_, sizeof(uint32)))
    {
        header_size_ = 0;
    }

    // 如果数据有问题, 不会继续使用.
    if(!header_size_)
    {
        header_ = NULL;
    }
}

Pickle::Pickle(const Pickle& other) : header_(NULL),
header_size_(other.header_size_), capacity_(0),
variable_buffer_offset_(other.variable_buffer_offset_)
{
    size_t payload_size = header_size_ + other.header_->payload_size;
    bool resized = Resize(payload_size);
    CHECK(resized); // realloc失败.
    memcpy(header_, other.header_, payload_size);
}

Pickle::~Pickle()
{
    if(capacity_ != kCapacityReadOnly)
    {
        free(header_);
    }
}

Pickle& Pickle::operator=(const Pickle& other)
{
    if(this == &other)
    {
        NOTREACHED();
        return *this;
    }
    if(capacity_ == kCapacityReadOnly)
    {
        header_ = NULL;
        capacity_ = 0;
    }
    if(header_size_ != other.header_size_)
    {
        free(header_);
        header_ = NULL;
        header_size_ = other.header_size_;
    }
    bool resized = Resize(other.header_size_+other.header_->payload_size);
    CHECK(resized); // realloc失败.
    memcpy(header_, other.header_,
        other.header_size_+other.header_->payload_size);
    variable_buffer_offset_ = other.variable_buffer_offset_;
    return *this;
}

bool Pickle::ReadBool(void** iter, bool* result) const
{
    DCHECK(iter);

    int tmp;
    if(!ReadInt(iter, &tmp))
    {
        return false;
    }
    DCHECK(0==tmp || 1==tmp);
    *result = tmp ? true : false;
    return true;
}

bool Pickle::ReadInt(void** iter, int* result) const
{
    DCHECK(iter);
    if(!*iter)
    {
        *iter = const_cast<char*>(payload());
    }

    if(!IteratorHasRoomFor(*iter, sizeof(*result)))
    {
        return false;
    }

    // TODO: http://crbug.com/13108 Pickle需要清理, 不应该依赖对齐.
    // 下面这行等同于: memcpy(result, *iter, sizeof(*result));
    *result = *reinterpret_cast<int*>(*iter);

    UpdateIter(iter, sizeof(*result));
    return true;
}

bool Pickle::ReadLong(void** iter, long* result) const
{
    DCHECK(iter);
    if(!*iter)
    {
        *iter = const_cast<char*>(payload());
    }

    if(!IteratorHasRoomFor(*iter, sizeof(*result)))
    {
        return false;
    }

    // TODO: http://crbug.com/13108 Pickle需要清理, 不应该依赖对齐.
    // 下面这行等同于: memcpy(result, *iter, sizeof(*result));
    memcpy(result, *iter, sizeof(*result));

    UpdateIter(iter, sizeof(*result));
    return true;
}

bool Pickle::ReadLength(void** iter, int* result) const
{
    if(!ReadInt(iter, result))
    {
        return false;
    }
    return ((*result) >= 0);
}

bool Pickle::ReadSize(void** iter, size_t* result) const
{
    DCHECK(iter);
    if(!*iter)
    {
        *iter = const_cast<char*>(payload());
    }

    if(!IteratorHasRoomFor(*iter, sizeof(*result)))
    {
        return false;
    }

    // TODO: http://crbug.com/13108 Pickle需要清理, 不应该依赖对齐.
    // 下面这行等同于: memcpy(result, *iter, sizeof(*result));
    *result = *reinterpret_cast<size_t*>(*iter);

    UpdateIter(iter, sizeof(*result));
    return true;
}

bool Pickle::ReadUInt16(void** iter, uint16* result) const
{
    DCHECK(iter);
    if(!*iter)
    {
        *iter = const_cast<char*>(payload());
    }

    if(!IteratorHasRoomFor(*iter, sizeof(*result)))
    {
        return false;
    }

    memcpy(result, *iter, sizeof(*result));

    UpdateIter(iter, sizeof(*result));
    return true;
}

bool Pickle::ReadUInt32(void** iter, uint32* result) const
{
    DCHECK(iter);
    if(!*iter)
    {
        *iter = const_cast<char*>(payload());
    }

    if(!IteratorHasRoomFor(*iter, sizeof(*result)))
    {
        return false;
    }

    memcpy(result, *iter, sizeof(*result));

    UpdateIter(iter, sizeof(*result));
    return true;
}

bool Pickle::ReadInt64(void** iter, int64* result) const
{
    DCHECK(iter);
    if(!*iter)
    {
        *iter = const_cast<char*>(payload());
    }

    if(!IteratorHasRoomFor(*iter, sizeof(*result)))
    {
        return false;
    }

    memcpy(result, *iter, sizeof(*result));

    UpdateIter(iter, sizeof(*result));
    return true;
}

bool Pickle::ReadUInt64(void** iter, uint64* result) const
{
    DCHECK(iter);
    if(!*iter)
    {
        *iter = const_cast<char*>(payload());
    }

    if(!IteratorHasRoomFor(*iter, sizeof(*result)))
    {
        return false;
    }

    memcpy(result, *iter, sizeof(*result));

    UpdateIter(iter, sizeof(*result));
    return true;
}

bool Pickle::ReadString(void** iter, std::string* result) const
{
    DCHECK(iter);

    int len;
    if(!ReadLength(iter, &len))
    {
        return false;
    }
    if(!IteratorHasRoomFor(*iter, len))
    {
        return false;
    }

    char* chars = reinterpret_cast<char*>(*iter);
    result->assign(chars, len);

    UpdateIter(iter, len);
    return true;
}

bool Pickle::ReadWString(void** iter, std::wstring* result) const
{
    DCHECK(iter);

    int len;
    if(!ReadLength(iter, &len))
    {
        return false;
    }
    // 避免整数溢出.
    if(len > INT_MAX/static_cast<int>(sizeof(wchar_t)))
    {
        return false;
    }
    if(!IteratorHasRoomFor(*iter, len*sizeof(wchar_t)))
    {
        return false;
    }

    wchar_t* chars = reinterpret_cast<wchar_t*>(*iter);
    result->assign(chars, len);

    UpdateIter(iter, len*sizeof(wchar_t));
    return true;
}

bool Pickle::ReadString16(void** iter, string16* result) const
{
    DCHECK(iter);

    int len;
    if(!ReadLength(iter, &len))
    {
        return false;
    }
    if(!IteratorHasRoomFor(*iter, len*sizeof(char16)))
    {
        return false;
    }

    char16* chars = reinterpret_cast<char16*>(*iter);
    result->assign(chars, len);

    UpdateIter(iter, len*sizeof(char16));
    return true;
}

bool Pickle::ReadBytes(void** iter, const char** data, int length) const
{
    DCHECK(iter);
    DCHECK(data);
    *data = 0;
    if(!*iter)
    {
        *iter = const_cast<char*>(payload());
    }

    if(!IteratorHasRoomFor(*iter, length))
    {
        return false;
    }

    *data = reinterpret_cast<const char*>(*iter);

    UpdateIter(iter, length);
    return true;
}

bool Pickle::ReadData(void** iter, const char** data, int* length) const
{
    DCHECK(iter);
    DCHECK(data);
    DCHECK(length);
    *length = 0;
    *data = 0;

    if(!ReadLength(iter, length))
    {
        return false;
    }

    return ReadBytes(iter, data, *length);
}

char* Pickle::BeginWrite(size_t length)
{
    // uint32对齐位置开始写.
    size_t offset = AlignInt(header_->payload_size, sizeof(uint32));

    size_t new_size = offset + length;
    size_t needed_size = header_size_ + new_size;
    if(needed_size>capacity_ && !Resize(std::max(capacity_*2, needed_size)))
    {
        return NULL;
    }

#ifdef ARCH_CPU_64_BITS
    DCHECK_LE(length, std::numeric_limits<uint32>::max());
#endif

    header_->payload_size = static_cast<uint32>(new_size);
    return payload() + offset;
}

void Pickle::EndWrite(char* dest, int length)
{
    // 用0填充避免类似valgrind这种内存工具报错.
    if(length % sizeof(uint32))
    {
        memset(dest+length, 0, sizeof(uint32)-(length%sizeof(uint32)));
    }
}

bool Pickle::WriteBytes(const void* data, int data_len)
{
    DCHECK(capacity_ != kCapacityReadOnly) << "oops: pickle is readonly";

    char* dest = BeginWrite(data_len);
    if(!dest)
    {
        return false;
    }

    memcpy(dest, data, data_len);

    EndWrite(dest, data_len);
    return true;
}

bool Pickle::WriteString(const std::string& value)
{
    if(!WriteInt(static_cast<int>(value.size())))
    {
        return false;
    }

    return WriteBytes(value.data(), static_cast<int>(value.size()));
}

bool Pickle::WriteWString(const std::wstring& value)
{
    if(!WriteInt(static_cast<int>(value.size())))
    {
        return false;
    }

    return WriteBytes(value.data(),
        static_cast<int>(value.size()*sizeof(wchar_t)));
}

bool Pickle::WriteString16(const string16& value)
{
    if(!WriteInt(static_cast<int>(value.size())))
    {
        return false;
    }

    return WriteBytes(value.data(),
        static_cast<int>(value.size())*sizeof(char16));
}

bool Pickle::WriteData(const char* data, int length)
{
    return length>=0 && WriteInt(length) && WriteBytes(data, length);
}

char* Pickle::BeginWriteData(int length)
{
    DCHECK_EQ(variable_buffer_offset_, 0U) <<
        "There can only be one variable buffer in a Pickle";

    if(length<0 || !WriteInt(length))
    {
        return NULL;
    }

    char* data_ptr = BeginWrite(length);
    if(!data_ptr)
    {
        return NULL;
    }

    variable_buffer_offset_ = data_ptr -
        reinterpret_cast<char*>(header_) - sizeof(int);

    // 数据写入后不必要再调用EndWrite, 所以在这里调用进行数据对齐.
    EndWrite(data_ptr, length);
    return data_ptr;
}

void Pickle::TrimWriteData(int new_length)
{
    DCHECK_NE(variable_buffer_offset_, 0U);

    // 获取变长缓冲区大小.
    int* cur_length = reinterpret_cast<int*>(
        reinterpret_cast<char*>(header_) + variable_buffer_offset_);

    if(new_length<0 || new_length>*cur_length)
    {
        NOTREACHED() << "Invalid length in TrimWriteData.";
        return;
    }

    // 更新有效数据长度和变长缓冲区大小.
    header_->payload_size -= (*cur_length - new_length);
    *cur_length = new_length;
}

bool Pickle::Resize(size_t new_capacity)
{
    new_capacity = AlignInt(new_capacity, kPayloadUnit);

    CHECK_NE(capacity_, kCapacityReadOnly);
    void* p = realloc(header_, new_capacity);
    if(!p)
    {
        return false;
    }

    header_ = reinterpret_cast<Header*>(p);
    capacity_ = new_capacity;
    return true;
}

// static
const char* Pickle::FindNext(size_t header_size,
                             const char* start,
                             const char* end)
{
    DCHECK(header_size == AlignInt(header_size, sizeof(uint32)));
    DCHECK(header_size <= static_cast<size_t>(kPayloadUnit));

    if(static_cast<size_t>(end-start) < sizeof(Header))
    {
        return NULL;
    }

    const Header* hdr = reinterpret_cast<const Header*>(start);
    const char* payload_base = start + header_size;
    const char* payload_end = payload_base + hdr->payload_size;
    if(payload_end < payload_base)
    {
        return NULL;
    }

    return (payload_end>end) ? NULL : payload_end;
}