// 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 <stdint.h>

#include <algorithm>

#include <blobfs/format.h>
#include <blobfs/iterator/block-iterator.h>
#include <blobfs/iterator/extent-iterator.h>
#include <zircon/types.h>

namespace blobfs {

BlockIterator::BlockIterator(ExtentIterator* iterator) : iterator_(iterator) {}

bool BlockIterator::Done() const {
    return blocks_left_ == 0 && iterator_->Done();
}

uint64_t BlockIterator::BlockIndex() const {
    return iterator_->BlockIndex() - blocks_left_;
}

zx_status_t BlockIterator::Next(uint32_t length, uint32_t* out_length, uint64_t* out_start) {
    ZX_DEBUG_ASSERT(!Done());

    // If there are no blocks left, refill the extent.
    if (!blocks_left_) {
        zx_status_t status = iterator_->Next(&extent_);
        if (status != ZX_OK) {
            return status;
        }
        blocks_left_ = extent_->Length();
    }

    // Return as many blocks as possible within this current extent.
    ZX_DEBUG_ASSERT(extent_ != nullptr);
    *out_length = std::min(blocks_left_, length);
    *out_start = (extent_->Start() + extent_->Length()) - blocks_left_;
    blocks_left_ -= *out_length;
    return ZX_OK;
}

zx_status_t StreamBlocks(BlockIterator* iterator, uint32_t block_count, StreamFn stream) {
    while (block_count > 0) {
        if (iterator->Done()) {
            FS_TRACE_ERROR("Failed to access data (early exit)\n");
            return ZX_ERR_IO_DATA_INTEGRITY;
        }
        uint64_t local_offset = iterator->BlockIndex();
        uint32_t actual_length;
        uint64_t dev_offset;
        zx_status_t status = iterator->Next(block_count, &actual_length, &dev_offset);
        if (status != ZX_OK) {
            FS_TRACE_ERROR("Failed to iterate over blocks: %d\n", status);
            return status;
        }
        status = stream(local_offset, dev_offset, actual_length);
        if (status != ZX_OK) {
            FS_TRACE_ERROR("Failed to enqueue blocks: %d\n", status);
            return status;
        }
        block_count -= actual_length;
    }
    return ZX_OK;
}

} // namespace blobfs