#pragma once

// STL includes
#include <vector>
#include <cstdint>
#include <cstring>
#include <algorithm>

template <typename Pixel_T>
class Image
{
public:

	typedef Pixel_T pixel_type;

	///
	/// Constructor for an image with specified width and height
	///
	/// @param width The width of the image
	/// @param height The height of the image
	///
	Image(const unsigned width, const unsigned height) :
		_width(width),
		_height(height),
		_pixels(new Pixel_T[width*height + 1]),
		_endOfPixels(_pixels + width*height)
	{
		memset(_pixels, 0, (_width*_height+1)*sizeof(Pixel_T));
	}

	///
	/// Constructor for an image with specified width and height
	///
	/// @param width The width of the image
	/// @param height The height of the image
	/// @param background The color of the image
	///
	Image(const unsigned width, const unsigned height, const Pixel_T background) :
		_width(width),
		_height(height),
		_pixels(new Pixel_T[width*height + 1]),
		_endOfPixels(_pixels + width*height)
	{
		std::fill(_pixels, _endOfPixels, background);
	}

	///
	/// Destructor
	///
	~Image()
	{
		delete[] _pixels;
	}

	///
	/// Returns the width of the image
	///
	/// @return The width of the image
	///
	inline unsigned width() const
	{
		return _width;
	}

	///
	/// Returns the height of the image
	///
	/// @return The height of the image
	///
	inline unsigned height() const
	{
		return _height;
	}

	uint8_t alpha(const unsigned pixel) const
	{
		return (_pixels + pixel)->red;
	}

	uint8_t red(const unsigned pixel) const
	{
		return (_pixels + pixel)->red;
	}

	uint8_t green(const unsigned pixel) const
	{
		return (_pixels + pixel)->green;
	}

	uint8_t blue(const unsigned pixel) const
	{
		return (_pixels + pixel)->blue;
	}

	///
	/// Returns a const reference to a specified pixel in the image
	///
	/// @param x The x index
	/// @param y The y index
	///
	/// @return const reference to specified pixel
	///
	const Pixel_T& operator()(const unsigned x, const unsigned y) const
	{
		return _pixels[toIndex(x,y)];
	}

	///
	/// Returns a reference to a specified pixel in the image
	///
	/// @param x The x index
	/// @param y The y index
	///
	/// @return reference to specified pixel
	///
	Pixel_T& operator()(const unsigned x, const unsigned y)
	{
		return _pixels[toIndex(x,y)];
	}

	/// Resize the image
	/// @param width The width of the image
	/// @param height The height of the image
	void resize(const unsigned width, const unsigned height)
	{
		if ((width*height) > (_endOfPixels-_pixels))
		{
			delete[] _pixels;
			_pixels = new Pixel_T[width*height + 1];
			_endOfPixels = _pixels + width*height;
		}

		_width = width;
		_height = height;
	}

	///
	/// Copies another image into this image. The images should have exactly the same size.
	///
	/// @param other The image to copy into this
	///
	void copy(const Image<Pixel_T>& other)
	{
		assert(other._width == _width);
		assert(other._height == _height);

		memcpy(_pixels, other._pixels, _width*_height*sizeof(Pixel_T));
	}

	///
	/// Returns a memory pointer to the first pixel in the image
	/// @return The memory pointer to the first pixel
	///
	Pixel_T* memptr()
	{
		return _pixels;
	}

	///
	/// Returns a const memory pointer to the first pixel in the image
	/// @return The const memory pointer to the first pixel
	///
	const Pixel_T* memptr() const
	{
		return _pixels;
	}
private:

	///
	/// Translate x and y coordinate to index of the underlying vector
	///
	/// @param x The x index
	/// @param y The y index
	///
	/// @return The index into the underlying data-vector
	///
	inline unsigned toIndex(const unsigned x, const unsigned y) const
	{
		return y*_width + x;
	}

private:
	/// The width of the image
	unsigned _width;
	/// The height of the image
	unsigned _height;

	/// The pixels of the image
	Pixel_T* _pixels;

	/// Pointer to the last(extra) pixel
	Pixel_T* _endOfPixels;
};