/* SPDX-License-Identifier: GPL-3.0-or-later

 * Copyright © 2022 The TokTok team.

 */

#include "bin_unpack.h"

#include <assert.h>

#include <stdlib.h>

#include <string.h>

#include "../third_party/cmp/cmp.h"

#include "ccompat.h"

struct Bin_Unpack {

    const uint8_t *bytes;

    uint32_t bytes_size;

    cmp_ctx_t ctx;

};

non_null()

static bool buf_reader(cmp_ctx_t *ctx, void *data, size_t limit)

{

    Bin_Unpack *reader = (Bin_Unpack *)ctx->buf;

    assert(reader != nullptr && reader->bytes != nullptr);

    if (limit > reader->bytes_size) {

        return false;

    }

    memcpy(data, reader->bytes, limit);

    reader->bytes += limit;

    reader->bytes_size -= limit;

    return true;

}

non_null()

static bool buf_skipper(cmp_ctx_t *ctx, size_t count)

{

    Bin_Unpack *reader = (Bin_Unpack *)ctx->buf;

    assert(reader != nullptr && reader->bytes != nullptr);

    if (count > reader->bytes_size) {

        return false;

    }

    reader->bytes += count;

    reader->bytes_size -= count;

    return true;

}

non_null()

static size_t null_writer(cmp_ctx_t *ctx, const void *data, size_t count)

{

    assert(count == 0);

    return 0;

}

non_null()

static void bin_unpack_init(Bin_Unpack *bu, const uint8_t *buf, uint32_t buf_size)

{

    bu->bytes = buf;

    bu->bytes_size = buf_size;

    cmp_init(&bu->ctx, bu, buf_reader, buf_skipper, null_writer);

}

bool bin_unpack_obj(bin_unpack_cb *callback, void *obj, const uint8_t *buf, uint32_t buf_size)

{

    Bin_Unpack bu;

    bin_unpack_init(&bu, buf, buf_size);

    return callback(obj, &bu);

}

bool bin_unpack_array(Bin_Unpack *bu, uint32_t *size)

{

    return cmp_read_array(&bu->ctx, size) && *size <= bu->bytes_size;

}

bool bin_unpack_array_fixed(Bin_Unpack *bu, uint32_t required_size, uint32_t *actual_size)

{

    uint32_t size = 0;

    const bool success = cmp_read_array(&bu->ctx, &size) && size == required_size;

    if (actual_size != nullptr) {

        *actual_size = size;

    }

    return success;

}

bool bin_unpack_bool(Bin_Unpack *bu, bool *val)

{

    return cmp_read_bool(&bu->ctx, val);

}

bool bin_unpack_u08(Bin_Unpack *bu, uint8_t *val)

{

    return cmp_read_uchar(&bu->ctx, val);

}

bool bin_unpack_u16(Bin_Unpack *bu, uint16_t *val)

{

    return cmp_read_ushort(&bu->ctx, val);

}

bool bin_unpack_u32(Bin_Unpack *bu, uint32_t *val)

{

    return cmp_read_uint(&bu->ctx, val);

}

bool bin_unpack_u64(Bin_Unpack *bu, uint64_t *val)

{

    return cmp_read_ulong(&bu->ctx, val);

}

bool bin_unpack_nil(Bin_Unpack *bu)

{

    return cmp_read_nil(&bu->ctx);

}

bool bin_unpack_bin(Bin_Unpack *bu, uint8_t **data_ptr, uint32_t *data_length_ptr)

{

    uint32_t bin_size;

    if (!bin_unpack_bin_size(bu, &bin_size) || bin_size > bu->bytes_size) {

        // There aren't as many bytes as this bin claims to want to allocate.

        return false;

    }

    uint8_t *const data = (uint8_t *)malloc(bin_size);

    if (!bin_unpack_bin_b(bu, data, bin_size)) {

        free(data);

        return false;

    }

    *data_ptr = data;

    *data_length_ptr = bin_size;

    return true;

}

bool bin_unpack_bin_max(Bin_Unpack *bu, uint8_t *data, uint16_t *data_length_ptr, uint16_t max_data_length)

{

    uint32_t bin_size;

    if (!bin_unpack_bin_size(bu, &bin_size) || bin_size > max_data_length) {

        return false;

    }

    *data_length_ptr = bin_size;

    return bin_unpack_bin_b(bu, data, bin_size);

}

bool bin_unpack_bin_fixed(Bin_Unpack *bu, uint8_t *data, uint32_t data_length)

{

    uint32_t bin_size;

    if (!bin_unpack_bin_size(bu, &bin_size) || bin_size != data_length) {

        return false;

    }

    return bin_unpack_bin_b(bu, data, bin_size);

}

bool bin_unpack_bin_size(Bin_Unpack *bu, uint32_t *size)

{

    return cmp_read_bin_size(&bu->ctx, size);

}

bool bin_unpack_u08_b(Bin_Unpack *bu, uint8_t *val)

{

    return bin_unpack_bin_b(bu, val, 1);

}

bool bin_unpack_u16_b(Bin_Unpack *bu, uint16_t *val)

{

    uint8_t hi = 0;

    uint8_t lo = 0;

    if (!(bin_unpack_u08_b(bu, &hi)

          && bin_unpack_u08_b(bu, &lo))) {

        return false;

    }

    *val = ((uint16_t)hi << 8) | lo;

    return true;

}

bool bin_unpack_u32_b(Bin_Unpack *bu, uint32_t *val)

{

    uint16_t hi = 0;

    uint16_t lo = 0;

    if (!(bin_unpack_u16_b(bu, &hi)

          && bin_unpack_u16_b(bu, &lo))) {

        return false;

    }

    *val = ((uint32_t)hi << 16) | lo;

    return true;

}

bool bin_unpack_u64_b(Bin_Unpack *bu, uint64_t *val)

{

    uint32_t hi = 0;

    uint32_t lo = 0;

    if (!(bin_unpack_u32_b(bu, &hi)

          && bin_unpack_u32_b(bu, &lo))) {

        return false;

    }

    *val = ((uint64_t)hi << 32) | lo;

    return true;

}

bool bin_unpack_bin_b(Bin_Unpack *bu, uint8_t *data, uint32_t length)

{

    return bu->ctx.read(&bu->ctx, data, length);

}