// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.

#include "precomp.h"

#include "OutputCellRect.hpp"

// Routine Description:
// - Constucts an empty in-memory region for holding output buffer cell data.
OutputCellRect::OutputCellRect() :
    _rows(0),
    _cols(0)
{

}

// Routine Description:
// - Constructs an in-memory region for holding a copy of output buffer cell data.
// - NOTE: This creatively skips the constructors for every cell. You must fill
//   every single cell in this rectangle before iterating/reading for it to be valid.
// - NOTE: This is designed for perf-sensitive paths ONLY. Take care.
// Arguments:
// - rows - Rows in the rectangle (height)
// - cols - Columns in the rectangle (width)
OutputCellRect::OutputCellRect(const size_t rows, const size_t cols) :
    _rows(rows),
    _cols(cols)
{
    size_t totalCells;
    THROW_IF_FAILED(SizeTMult(rows, cols, &totalCells));

    _storage.resize(totalCells);
}

// Routine Description:
// - Gets a read/write span over a single row inside the rectangle.
// Arguments:
// - row - The Y position or row index in the buffer.
// Return Value:
// - Read/write span of OutputCells
gsl::span<OutputCell> OutputCellRect::GetRow(const size_t row)
{
    return gsl::span<OutputCell>(_FindRowOffset(row), _cols);
}

// Routine Description:
// - Gets a read-only iterator view over a single row of the rectangle.
// Arguments:
// - row - The Y position or row index in the buffer.
// Return Value:
// - Read-only iterator of OutputCells
OutputCellIterator OutputCellRect::GetRowIter(const size_t row) const
{
    const std::basic_string_view<OutputCell> view(_FindRowOffset(row), _cols);

    return OutputCellIterator(view);
}

// Routine Description:
// - Internal helper to find the pointer to the specific row offset in the giant 
//   contiguous block of memory allocated for this rectangle.
// Arguments:
// - row - The Y position or row index in the buffer.
// Return Value:
// - Pointer to the location in the rectangle that represents the start of the requested row.
OutputCell* OutputCellRect::_FindRowOffset(const size_t row)
{
    return (_storage.data() + (row * _cols));
}

// Routine Description:
// - Internal helper to find the pointer to the specific row offset in the giant 
//   contiguous block of memory allocated for this rectangle.
// Arguments:
// - row - The Y position or row index in the buffer.
// Return Value:
// - Pointer to the location in the rectangle that represents the start of the requested row.
const OutputCell* OutputCellRect::_FindRowOffset(const size_t row) const
{
    return (_storage.data() + (row * _cols));
}

// Routine Description:
// - Gets the height of the rectangle
// Return Value:
// - Height
size_t OutputCellRect::Height() const noexcept
{
    return _rows;
}

// Routine Description:
// - Gets the width of the rectangle
// Return Value:
// - Width
size_t OutputCellRect::Width() const noexcept
{
    return _cols;
}