/* 7zStream.c -- 7z Stream functions
2010-03-11 : Igor Pavlov : Public domain */

#include <string.h>

#include "Types.h"

SRes SeqInStream_Read2(ISeqInStream* stream, void* buf, size_t size, SRes errorType)
{
    while (size != 0) {
        size_t processed = size;
        RINOK(stream->Read(stream, buf, &processed));
        if (processed == 0)
            return errorType;
        buf = (void*)((Byte*)buf + processed);
        size -= processed;
    }
    return SZ_OK;
}

SRes SeqInStream_Read(ISeqInStream* stream, void* buf, size_t size)
{
    return SeqInStream_Read2(stream, buf, size, SZ_ERROR_INPUT_EOF);
}

SRes SeqInStream_ReadByte(ISeqInStream* stream, Byte* buf)
{
    size_t processed = 1;
    RINOK(stream->Read(stream, buf, &processed));
    return (processed == 1) ? SZ_OK : SZ_ERROR_INPUT_EOF;
}

SRes LookInStream_SeekTo(ILookInStream* stream, UInt64 offset)
{
    Int64 t = offset;
    return stream->Seek(stream, &t, SZ_SEEK_SET);
}

SRes LookInStream_LookRead(ILookInStream* stream, void* buf, size_t* size)
{
    const void* lookBuf;
    if (*size == 0)
        return SZ_OK;
    RINOK(stream->Look(stream, &lookBuf, size));
    memcpy(buf, lookBuf, *size);
    return stream->Skip(stream, *size);
}

SRes LookInStream_Read2(ILookInStream* stream, void* buf, size_t size, SRes errorType)
{
    while (size != 0) {
        size_t processed = size;
        RINOK(stream->Read(stream, buf, &processed));
        if (processed == 0)
            return errorType;
        buf = (void*)((Byte*)buf + processed);
        size -= processed;
    }
    return SZ_OK;
}

SRes LookInStream_Read(ILookInStream* stream, void* buf, size_t size)
{
    return LookInStream_Read2(stream, buf, size, SZ_ERROR_INPUT_EOF);
}

static SRes LookToRead_Look_Lookahead(void* pp, const void** buf, size_t* size)
{
    SRes res = SZ_OK;
    CLookToRead* p = (CLookToRead*)pp;
    size_t size2 = p->size - p->pos;
    if (size2 == 0 && *size > 0) {
        p->pos = 0;
        size2 = LookToRead_BUF_SIZE;
        res = p->realStream->Read(p->realStream, p->buf, &size2);
        p->size = size2;
    }
    if (size2 < *size)
        *size = size2;
    *buf = p->buf + p->pos;
    return res;
}

static SRes LookToRead_Look_Exact(void* pp, const void** buf, size_t* size)
{
    SRes res = SZ_OK;
    CLookToRead* p = (CLookToRead*)pp;
    size_t size2 = p->size - p->pos;
    if (size2 == 0 && *size > 0) {
        p->pos = 0;
        if (*size > LookToRead_BUF_SIZE)
            *size = LookToRead_BUF_SIZE;
        res = p->realStream->Read(p->realStream, p->buf, size);
        size2 = p->size = *size;
    }
    if (size2 < *size)
        *size = size2;
    *buf = p->buf + p->pos;
    return res;
}

static SRes LookToRead_Skip(void* pp, size_t offset)
{
    CLookToRead* p = (CLookToRead*)pp;
    p->pos += offset;
    return SZ_OK;
}

static SRes LookToRead_Read(void* pp, void* buf, size_t* size)
{
    CLookToRead* p = (CLookToRead*)pp;
    size_t rem = p->size - p->pos;
    if (rem == 0)
        return p->realStream->Read(p->realStream, buf, size);
    if (rem > *size)
        rem = *size;
    memcpy(buf, p->buf + p->pos, rem);
    p->pos += rem;
    *size = rem;
    return SZ_OK;
}

static SRes LookToRead_Seek(void* pp, Int64* pos, ESzSeek origin)
{
    CLookToRead* p = (CLookToRead*)pp;
    p->pos = p->size = 0;
    return p->realStream->Seek(p->realStream, pos, origin);
}

void LookToRead_CreateVTable(CLookToRead* p, int lookahead)
{
    p->s.Look = lookahead ? LookToRead_Look_Lookahead : LookToRead_Look_Exact;
    p->s.Skip = LookToRead_Skip;
    p->s.Read = LookToRead_Read;
    p->s.Seek = LookToRead_Seek;
}

void LookToRead_Init(CLookToRead* p)
{
    p->pos = p->size = 0;
}

static SRes SecToLook_Read(void* pp, void* buf, size_t* size)
{
    CSecToLook* p = (CSecToLook*)pp;
    return LookInStream_LookRead(p->realStream, buf, size);
}

void SecToLook_CreateVTable(CSecToLook* p)
{
    p->s.Read = SecToLook_Read;
}

static SRes SecToRead_Read(void* pp, void* buf, size_t* size)
{
    CSecToRead* p = (CSecToRead*)pp;
    return p->realStream->Read(p->realStream, buf, size);
}

void SecToRead_CreateVTable(CSecToRead* p)
{
    p->s.Read = SecToRead_Read;
}