// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <cstdint>
#include <limits>

#include <lib/fidl/walker.h>

namespace fidl {

zx_status_t PrimaryObjectSize(const fidl_type_t* type,
                              size_t* out_size,
                              const char** out_error) {
    auto set_error = [&out_error](const char* msg) {
        if (out_error)
            *out_error = msg;
    };
    if (type == nullptr) {
        set_error("fidl type cannot be null");
        return ZX_ERR_INVALID_ARGS;
    }
    switch (type->type_tag) {
    case fidl::kFidlTypeStruct:
        *out_size = type->coded_struct.size;
        return ZX_OK;
    case fidl::kFidlTypeTable:
        *out_size = sizeof(fidl_vector_t);
        return ZX_OK;
    default:
        set_error("Message must be a struct or a table");
        return ZX_ERR_INVALID_ARGS;
    }
}

zx_status_t StartingOutOfLineOffset(const fidl_type_t* type,
                                    uint32_t buffer_size,
                                    uint32_t* out_first_out_of_line,
                                    const char** out_error) {
    auto set_error = [&out_error](const char* msg) {
        if (out_error)
            *out_error = msg;
    };
    size_t primary_size;
    zx_status_t status;
    if ((status = PrimaryObjectSize(type, &primary_size, out_error)) != ZX_OK) {
        return status;
    }
    if (primary_size > buffer_size) {
        set_error("Buffer is too small for first inline object");
        return ZX_ERR_INVALID_ARGS;
    }
    uint64_t first_out_of_line = fidl::FidlAlign(static_cast<uint32_t>(primary_size));
    if (first_out_of_line > std::numeric_limits<uint32_t>::max()) {
        set_error("Out of line starting offset overflows");
        return ZX_ERR_INVALID_ARGS;
    }
    *out_first_out_of_line = static_cast<uint32_t>(first_out_of_line);
    return ZX_OK;
}

} // namespace fidl