// Copyright 2019 Joe Drago. All rights reserved.

// SPDX-License-Identifier: BSD-2-Clause

#include "avif/internal.h"

#include <assert.h>

#include <inttypes.h>

#include <stdlib.h>

#include <string.h>

// ---------------------------------------------------------------------------

// avifROStream

const uint8_t * avifROStreamCurrent(avifROStream * stream)

{

    return stream->raw->data + stream->offset;

}

void avifROStreamStart(avifROStream * stream, avifROData * raw, avifDiagnostics * diag, const char * diagContext)

{

    stream->raw = raw;

    stream->offset = 0;

    stream->numUsedBitsInPartialByte = 0;

    stream->diag = diag;

    stream->diagContext = diagContext;

    // If diag is non-NULL, diagContext must also be non-NULL

    assert(!stream->diag || stream->diagContext);

}

avifBool avifROStreamHasBytesLeft(const avifROStream * stream, size_t byteCount)

{

    return byteCount <= (stream->raw->size - stream->offset);

}

size_t avifROStreamRemainingBytes(const avifROStream * stream)

{

    return stream->raw->size - stream->offset;

}

size_t avifROStreamOffset(const avifROStream * stream)

{

    return stream->offset;

}

void avifROStreamSetOffset(avifROStream * stream, size_t offset)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    stream->offset = offset;

    if (stream->offset > stream->raw->size) {

        stream->offset = stream->raw->size;

    }

}

avifBool avifROStreamSkip(avifROStream * stream, size_t byteCount)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    if (!avifROStreamHasBytesLeft(stream, byteCount)) {

        avifDiagnosticsPrintf(stream->diag, "%s: Failed to skip %zu bytes, truncated data?", stream->diagContext, byteCount);

        return AVIF_FALSE;

    }

    stream->offset += byteCount;

    return AVIF_TRUE;

}

avifBool avifROStreamRead(avifROStream * stream, uint8_t * data, size_t size)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    if (!avifROStreamHasBytesLeft(stream, size)) {

        avifDiagnosticsPrintf(stream->diag, "%s: Failed to read %zu bytes, truncated data?", stream->diagContext, size);

        return AVIF_FALSE;

    }

    memcpy(data, stream->raw->data + stream->offset, size);

    stream->offset += size;

    return AVIF_TRUE;

}

avifBool avifROStreamReadUX8(avifROStream * stream, uint64_t * v, uint64_t factor)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    if (factor == 0) {

        // Don't read anything, just set to 0

        *v = 0;

    } else if (factor == 1) {

        uint8_t tmp;

        AVIF_CHECK(avifROStreamRead(stream, &tmp, 1));

        *v = tmp;

    } else if (factor == 2) {

        uint16_t tmp;

        AVIF_CHECK(avifROStreamReadU16(stream, &tmp));

        *v = tmp;

    } else if (factor == 4) {

        uint32_t tmp;

        AVIF_CHECK(avifROStreamReadU32(stream, &tmp));

        *v = tmp;

    } else if (factor == 8) {

        uint64_t tmp;

        AVIF_CHECK(avifROStreamReadU64(stream, &tmp));

        *v = tmp;

    } else {

        // Unsupported factor

        avifDiagnosticsPrintf(stream->diag, "%s: Failed to read UX8 value; Unsupported UX8 factor [%" PRIu64 "]", stream->diagContext, factor);

        return AVIF_FALSE;

    }

    return AVIF_TRUE;

}

avifBool avifROStreamReadU16(avifROStream * stream, uint16_t * v)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    AVIF_CHECK(avifROStreamRead(stream, (uint8_t *)v, sizeof(uint16_t)));

    *v = avifNTOHS(*v);

    return AVIF_TRUE;

}

avifBool avifROStreamReadU16Endianness(avifROStream * stream, uint16_t * v, avifBool littleEndian)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    AVIF_CHECK(avifROStreamRead(stream, (uint8_t *)v, sizeof(uint16_t)));

    *v = littleEndian ? avifCTOHS(*v) : avifNTOHS(*v);

    return AVIF_TRUE;

}

avifBool avifROStreamReadU32(avifROStream * stream, uint32_t * v)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    AVIF_CHECK(avifROStreamRead(stream, (uint8_t *)v, sizeof(uint32_t)));

    *v = avifNTOHL(*v);

    return AVIF_TRUE;

}

avifBool avifROStreamReadU32Endianness(avifROStream * stream, uint32_t * v, avifBool littleEndian)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    AVIF_CHECK(avifROStreamRead(stream, (uint8_t *)v, sizeof(uint32_t)));

    *v = littleEndian ? avifCTOHL(*v) : avifNTOHL(*v);

    return AVIF_TRUE;

}

avifBool avifROStreamReadU64(avifROStream * stream, uint64_t * v)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    AVIF_CHECK(avifROStreamRead(stream, (uint8_t *)v, sizeof(uint64_t)));

    *v = avifNTOH64(*v);

    return AVIF_TRUE;

}

avifBool avifROStreamSkipBits(avifROStream * stream, size_t bitCount)

{

    if (stream->numUsedBitsInPartialByte != 0) {

        assert(stream->numUsedBitsInPartialByte < 8);

        const size_t padding = AVIF_MIN(8 - stream->numUsedBitsInPartialByte, bitCount);

        stream->numUsedBitsInPartialByte = (stream->numUsedBitsInPartialByte + padding) % 8;

        bitCount -= padding;

        if (bitCount == 0) {

            return AVIF_TRUE;

        }

    }

    const size_t num_bytes = (bitCount + 7) / 8;

    AVIF_CHECK(avifROStreamSkip(stream, num_bytes));

    stream->numUsedBitsInPartialByte = bitCount % 8;

    return AVIF_TRUE;

}

avifBool avifROStreamReadBitsU8(avifROStream * stream, uint8_t * v, size_t bitCount)

{

    AVIF_CHECK(bitCount <= sizeof(*v) * 8);

    uint32_t vU32;

    AVIF_CHECK(avifROStreamReadBitsU32(stream, &vU32, bitCount));

    *v = (uint8_t)vU32;

    return AVIF_TRUE;

}

avifBool avifROStreamReadBitsU16(avifROStream * stream, uint16_t * v, size_t bitCount)

{

    AVIF_CHECK(bitCount <= sizeof(*v) * 8);

    uint32_t vU32;

    AVIF_CHECK(avifROStreamReadBitsU32(stream, &vU32, bitCount));

    *v = (uint16_t)vU32;

    return AVIF_TRUE;

}

avifBool avifROStreamReadBitsU32(avifROStream * stream, uint32_t * v, size_t bitCount)

{

    AVIF_CHECK(bitCount <= sizeof(*v) * 8);

    *v = 0;

    while (bitCount) {

        if (stream->numUsedBitsInPartialByte == 0) {

            AVIF_CHECK(avifROStreamSkip(stream, sizeof(uint8_t))); // Book a new partial byte in the stream.

        }

        assert(stream->offset > 0);

        const uint8_t * packedBits = stream->raw->data + stream->offset - 1;

        const size_t numBits = AVIF_MIN(bitCount, 8 - stream->numUsedBitsInPartialByte);

        stream->numUsedBitsInPartialByte += numBits;

        bitCount -= numBits;

        // The stream bits are packed starting with the most significant bit of the first input byte.

        // This way, packed bits can be found in the same order in the bit stream.

        const uint32_t bits = (*packedBits >> (8 - stream->numUsedBitsInPartialByte)) & ((1 << numBits) - 1);

        // The value bits are ordered from the most significant bit to the least significant bit.

        // In the case where avifROStreamReadBitsU32() is used to parse the unsigned integer value *v

        // over multiple aligned bytes, this order corresponds to big endianness.

        *v |= bits << bitCount;

        if (stream->numUsedBitsInPartialByte == 8) {

            // Start a new partial byte the next time a bit is needed.

            stream->numUsedBitsInPartialByte = 0;

        }

    }

    return AVIF_TRUE;

}

avifBool avifROStreamReadString(avifROStream * stream, char * output, size_t outputSize)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    // Check for the presence of a null terminator in the stream.

    size_t remainingBytes = avifROStreamRemainingBytes(stream);

    const uint8_t * p = avifROStreamCurrent(stream);

    avifBool foundNullTerminator = AVIF_FALSE;

    for (size_t i = 0; i < remainingBytes; ++i) {

        if (p[i] == 0) {

            foundNullTerminator = AVIF_TRUE;

            break;

        }

    }

    if (!foundNullTerminator) {

        avifDiagnosticsPrintf(stream->diag, "%s: Failed to find a NULL terminator when reading a string", stream->diagContext);

        return AVIF_FALSE;

    }

    const char * streamString = (const char *)p;

    size_t stringLen = strlen(streamString);

    stream->offset += stringLen + 1; // update the stream to have read the "whole string" in

    if (output && outputSize) {

        // clamp to our output buffer

        if (stringLen >= outputSize) {

            stringLen = outputSize - 1;

        }

        memcpy(output, streamString, stringLen);

        output[stringLen] = 0;

    }

    return AVIF_TRUE;

}

avifBool avifROStreamReadBoxHeaderPartial(avifROStream * stream, avifBoxHeader * header, avifBool topLevel)

{

    // Section 4.2.2 of ISO/IEC 14496-12.

    size_t startOffset = stream->offset;

    uint32_t smallSize;

    AVIF_CHECK(avifROStreamReadU32(stream, &smallSize));   // unsigned int(32) size;

    AVIF_CHECK(avifROStreamRead(stream, header->type, 4)); // unsigned int(32) type = boxtype;

    uint64_t size = smallSize;

    if (size == 1) {

        AVIF_CHECK(avifROStreamReadU64(stream, &size)); // unsigned int(64) largesize;

    }

    if (!memcmp(header->type, "uuid", 4)) {

        AVIF_CHECK(avifROStreamRead(stream, header->usertype, 16)); // unsigned int(8) usertype[16] = extended_type;

    } else {

        memset(header->usertype, 0, sizeof(header->usertype));

    }

    size_t bytesRead = stream->offset - startOffset;

    if (size == 0) {

        // Section 4.2.2 of ISO/IEC 14496-12.

        //   if size is 0, then this box shall be in a top-level box (i.e. not contained in another

        //   box), and be the last box in its 'file', and its payload extends to the end of that

        //   enclosing 'file'. This is normally only used for a MediaDataBox ('mdat').

        if (!topLevel) {

            avifDiagnosticsPrintf(stream->diag, "%s: Non-top-level box with size 0", stream->diagContext);

            return AVIF_FALSE;

        }

        // The given stream may be incomplete and there is no guarantee that sizeHint is available and accurate.

        // Otherwise size could be set to avifROStreamRemainingBytes(stream) + (stream->offset - startOffset) right now.

        // Wait for avifIOReadFunc() to return AVIF_RESULT_OK.

        header->isSizeZeroBox = AVIF_TRUE;

        header->size = 0;

        return AVIF_TRUE;

    }

    if ((size < bytesRead) || ((size - bytesRead) > SIZE_MAX)) {

        avifDiagnosticsPrintf(stream->diag, "%s: Header size overflow check failure", stream->diagContext);

        return AVIF_FALSE;

    }

    header->isSizeZeroBox = AVIF_FALSE;

    header->size = (size_t)(size - bytesRead);

    return AVIF_TRUE;

}

avifBool avifROStreamReadBoxHeader(avifROStream * stream, avifBoxHeader * header)

{

    AVIF_CHECK(avifROStreamReadBoxHeaderPartial(stream, header, /*topLevel=*/AVIF_FALSE));

    if (header->size > avifROStreamRemainingBytes(stream)) {

        avifDiagnosticsPrintf(stream->diag, "%s: Child box too large, possibly truncated data", stream->diagContext);

        return AVIF_FALSE;

    }

    return AVIF_TRUE;

}

avifBool avifROStreamReadVersionAndFlags(avifROStream * stream, uint8_t * version, uint32_t * flags)

{

    uint8_t versionAndFlags[4];

    AVIF_CHECK(avifROStreamRead(stream, versionAndFlags, 4));

    if (version) {

        *version = versionAndFlags[0];

    }

    if (flags) {

        *flags = (versionAndFlags[1] << 16) + (versionAndFlags[2] << 8) + (versionAndFlags[3] << 0);

    }

    return AVIF_TRUE;

}

avifBool avifROStreamReadAndEnforceVersion(avifROStream * stream, uint8_t enforcedVersion, uint32_t * flags)

{

    uint8_t version;

    AVIF_CHECK(avifROStreamReadVersionAndFlags(stream, &version, flags));

    if (version != enforcedVersion) {

        avifDiagnosticsPrintf(stream->diag, "%s: Expecting box version %u, got version %u", stream->diagContext, enforcedVersion, version);

        return AVIF_FALSE;

    }

    return AVIF_TRUE;

}

// ---------------------------------------------------------------------------

// avifRWStream

#define AVIF_STREAM_BUFFER_INCREMENT (1024 * 1024)

static avifResult makeRoom(avifRWStream * stream, size_t size)

{

    size_t neededSize = stream->offset + size;

    size_t newSize = stream->raw->size;

    while (newSize < neededSize) {

        newSize += AVIF_STREAM_BUFFER_INCREMENT;

    }

    return avifRWDataRealloc(stream->raw, newSize);

}

void avifRWStreamStart(avifRWStream * stream, avifRWData * raw)

{

    stream->raw = raw;

    stream->offset = 0;

    stream->numUsedBitsInPartialByte = 0;

}

size_t avifRWStreamOffset(const avifRWStream * stream)

{

    return stream->offset;

}

void avifRWStreamSetOffset(avifRWStream * stream, size_t offset)

{

    stream->offset = offset;

    if (stream->offset > stream->raw->size) {

        stream->offset = stream->raw->size;

    }

}

void avifRWStreamFinishWrite(avifRWStream * stream)

{

    if (stream->raw->size != stream->offset) {

        if (stream->offset) {

            stream->raw->size = stream->offset;

        } else {

            avifRWDataFree(stream->raw);

        }

    }

}

avifResult avifRWStreamWrite(avifRWStream * stream, const void * data, size_t size)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    if (size) {

        AVIF_CHECKRES(makeRoom(stream, size));

        memcpy(stream->raw->data + stream->offset, data, size);

        stream->offset += size;

    }

    return AVIF_RESULT_OK;

}

avifResult avifRWStreamWriteChars(avifRWStream * stream, const char * chars, size_t size)

{

    return avifRWStreamWrite(stream, chars, size);

}

avifResult avifRWStreamWriteFullBox(avifRWStream * stream, const char * type, size_t contentSize, int version, uint32_t flags, avifBoxMarker * marker)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    if (marker) {

        *marker = stream->offset;

    }

    size_t headerSize = sizeof(uint32_t) + 4 /* size of type */;

    if (version != -1) {

        headerSize += 4;

    }

    AVIF_CHECKRES(makeRoom(stream, headerSize));

    memset(stream->raw->data + stream->offset, 0, headerSize);

    uint32_t noSize = avifHTONL((uint32_t)(headerSize + contentSize));

    memcpy(stream->raw->data + stream->offset, &noSize, sizeof(uint32_t));

    memcpy(stream->raw->data + stream->offset + 4, type, 4);

    if (version != -1) {

        stream->raw->data[stream->offset + 8] = (uint8_t)version;

        stream->raw->data[stream->offset + 9] = (uint8_t)((flags >> 16) & 0xff);

        stream->raw->data[stream->offset + 10] = (uint8_t)((flags >> 8) & 0xff);

        stream->raw->data[stream->offset + 11] = (uint8_t)((flags >> 0) & 0xff);

    }

    stream->offset += headerSize;

    return AVIF_RESULT_OK;

}

avifResult avifRWStreamWriteBox(avifRWStream * stream, const char * type, size_t contentSize, avifBoxMarker * marker)

{

    return avifRWStreamWriteFullBox(stream, type, contentSize, -1, 0, marker);

}

void avifRWStreamFinishBox(avifRWStream * stream, avifBoxMarker marker)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    uint32_t noSize = avifHTONL((uint32_t)(stream->offset - marker));

    memcpy(stream->raw->data + marker, &noSize, sizeof(uint32_t));

}

avifResult avifRWStreamWriteU8(avifRWStream * stream, uint8_t v)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    AVIF_CHECKRES(makeRoom(stream, 1));

    stream->raw->data[stream->offset] = v;

    stream->offset += 1;

    return AVIF_RESULT_OK;

}

avifResult avifRWStreamWriteU16(avifRWStream * stream, uint16_t v)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    const size_t size = sizeof(uint16_t);

    AVIF_CHECKRES(makeRoom(stream, size));

    v = avifHTONS(v);

    memcpy(stream->raw->data + stream->offset, &v, size);

    stream->offset += size;

    return AVIF_RESULT_OK;

}

avifResult avifRWStreamWriteU32(avifRWStream * stream, uint32_t v)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    const size_t size = sizeof(uint32_t);

    AVIF_CHECKRES(makeRoom(stream, size));

    v = avifHTONL(v);

    memcpy(stream->raw->data + stream->offset, &v, size);

    stream->offset += size;

    return AVIF_RESULT_OK;

}

avifResult avifRWStreamWriteU64(avifRWStream * stream, uint64_t v)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    const size_t size = sizeof(uint64_t);

    AVIF_CHECKRES(makeRoom(stream, size));

    v = avifHTON64(v);

    memcpy(stream->raw->data + stream->offset, &v, size);

    stream->offset += size;

    return AVIF_RESULT_OK;

}

avifResult avifRWStreamWriteZeros(avifRWStream * stream, size_t byteCount)

{

    assert(stream->numUsedBitsInPartialByte == 0); // Byte alignment is required.

    AVIF_CHECKRES(makeRoom(stream, byteCount));

    memset(stream->raw->data + stream->offset, 0, byteCount);

    stream->offset += byteCount;

    return AVIF_RESULT_OK;

}

avifResult avifRWStreamWriteBits(avifRWStream * stream, uint32_t v, size_t bitCount)

{

    AVIF_CHECKERR(bitCount >= 32 || (v >> bitCount) == 0, AVIF_RESULT_INVALID_ARGUMENT);

    while (bitCount) {

        if (stream->numUsedBitsInPartialByte == 0) {

            AVIF_CHECKRES(makeRoom(stream, 1)); // Book a new partial byte in the stream.

            stream->raw->data[stream->offset] = 0;

            stream->offset += 1;

        }

        assert(stream->offset > 0);

        uint8_t * packedBits = stream->raw->data + stream->offset - 1;

        const size_t numBits = AVIF_MIN(bitCount, 8 - stream->numUsedBitsInPartialByte);

        stream->numUsedBitsInPartialByte += numBits;

        bitCount -= numBits;

        // Order the input bits from the most significant bit to the least significant bit.

        // In the case where avifRWStreamWriteBits() is used to write the unsigned integer value v

        // over multiple aligned bytes, this order corresponds to big endianness.

        const uint32_t bits = (v >> bitCount) & ((1 << numBits) - 1);

        // Pack bits starting with the most significant bit of the first output byte.

        // This way, packed bits can be found in the same order in the bit stream.

        *packedBits |= bits << (8 - stream->numUsedBitsInPartialByte);

        if (stream->numUsedBitsInPartialByte == 8) {

            // Start a new partial byte the next time a bit is needed.

            stream->numUsedBitsInPartialByte = 0;

        }

    }

    return AVIF_RESULT_OK;

}