// Copyright 2019 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 "stream-reader.h"

#include <fuchsia/paver/c/fidl.h>

#include "pave-logging.h"

namespace paver {

zx_status_t StreamReader::Create(zx::channel stream, fbl::unique_ptr<StreamReader>* reader) {
    zx::vmo vmo;
    auto status = zx::vmo::create(8192, 0, &vmo);
    if (status != ZX_OK) {
        ERROR("Unable to create vmo.\n");
        return status;
    }
    zx::vmo dup;
    status = vmo.duplicate(ZX_RIGHT_SAME_RIGHTS, &dup);
    if (status != ZX_OK) {
        ERROR("Unable to duplicate vmo.\n");
        return status;
    }
    zx_status_t status2;
    status = fuchsia_paver_PayloadStreamRegisterVmo(stream.get(), dup.release(), &status2);
    status = status == ZX_OK ? status2 : status;
    if (status != ZX_OK) {
        ERROR("Unable to register vmo: %d\n", status);
        return status;
    }
    reader->reset(new StreamReader(std::move(stream), std::move(vmo)));
    return ZX_OK;
}

zx_status_t StreamReader::Read(void* buf, size_t buf_size, size_t* size_actual) {
    if (size_ == 0) {
        fuchsia_paver_ReadResult result;
        auto status = fuchsia_paver_PayloadStreamReadData(stream_.get(), &result);
        if (status != ZX_OK) {
            return status;
        }
        switch (result.tag) {
        case fuchsia_paver_ReadResultTag_err:
            return result.err;
        case fuchsia_paver_ReadResultTag_eof:
            *size_actual = 0;
            return ZX_OK;
        case fuchsia_paver_ReadResultTag_info:
            offset_ = result.info.offset;
            size_ = result.info.size;
            break;
        default:
            return ZX_ERR_INTERNAL;
        }
    }
    const auto size = std::min(size_, buf_size);
    auto status = vmo_.read(buf, offset_, size);
    if (status != ZX_OK) {
        return status;
    }
    offset_ += size;
    size_ -= size;
    *size_actual = size;
    return ZX_OK;
}

} // namespace paver