/**
 * @file base.h
 * @brief Basic citro2d initialization and drawing API
 */
#pragma once
#include <citro3d.h>
#include <tex3ds.h>

#define C2D_DEFAULT_MAX_OBJECTS 4096

#ifdef __cplusplus
#define C2D_CONSTEXPR constexpr
#define C2D_OPTIONAL(_x) =_x
#else
#define C2D_CONSTEXPR static inline
#define C2D_OPTIONAL(_x)
#endif

typedef struct
{
	struct
	{
		float x, y, w, h;
	} pos;

	struct
	{
		float x, y;
	} center;

	float depth;
	float angle;
} C2D_DrawParams;

typedef enum
{
	C2D_TintSolid, ///< Plain solid tint color
	C2D_TintMult,  ///< Tint color multiplied by texture color
	C2D_TintLuma,  ///< Tint color multiplied by grayscale converted texture color
} C2D_TintMode;

typedef struct
{
	u32   color; ///< RGB tint color and Alpha transparency
	float blend; ///< Blending strength of the tint color (0.0~1.0)
} C2D_Tint;

typedef enum
{
	C2D_TopLeft,  ///< Top left corner
	C2D_TopRight, ///< Top right corner
	C2D_BotLeft,  ///< Bottom left corner
	C2D_BotRight, ///< Bottom right corner
} C2D_Corner;

typedef struct
{
	C3D_Tex* tex;
	const Tex3DS_SubTexture* subtex;
} C2D_Image;

typedef struct
{
	C2D_Tint corners[4];
} C2D_ImageTint;

/** @defgroup Helper Helper functions
 *  @{
 */

/** @brief Clamps a value between bounds
 *  @param[in] x The value to clamp
 *  @param[in] min The lower bound
 *  @param[in] max The upper bound
 *  @returns The clamped value
 */
C2D_CONSTEXPR float C2D_Clamp(float x, float min, float max)
{
	return x <= min ? min : x >= max ? max : x;
}

/** @brief Converts a float to u8
 *  @param[in] x Input value (0.0~1.0)
 *  @returns Output value (0~255)
 */
C2D_CONSTEXPR u8 C2D_FloatToU8(float x)
{
	return (u8)(255.0f*C2D_Clamp(x, 0.0f, 1.0f)+0.5f);
}

/** @brief Builds a 32-bit RGBA color value
 *  @param[in] r Red component (0~255)
 *  @param[in] g Green component (0~255)
 *  @param[in] b Blue component (0~255)
 *  @param[in] a Alpha component (0~255)
 *  @returns The 32-bit RGBA color value
 */
C2D_CONSTEXPR u32 C2D_Color32(u8 r, u8 g, u8 b, u8 a)
{
	return r | (g << (u32)8) | (b << (u32)16) | (a << (u32)24);
}

/** @brief Builds a 32-bit RGBA color value from float values
 *  @param[in] r Red component (0.0~1.0)
 *  @param[in] g Green component (0.0~1.0)
 *  @param[in] b Blue component (0.0~1.0)
 *  @param[in] a Alpha component (0.0~1.0)
 *  @returns The 32-bit RGBA color value
 */
C2D_CONSTEXPR u32 C2D_Color32f(float r, float g, float b, float a)
{
	return C2D_Color32(C2D_FloatToU8(r),C2D_FloatToU8(g),C2D_FloatToU8(b),C2D_FloatToU8(a));
}

/** @brief Configures one corner of an image tint structure
 *  @param[in] tint Image tint structure
 *  @param[in] corner The corner of the image to tint
 *  @param[in] color RGB tint color and Alpha transparency
 *  @param[in] blend Blending strength of the tint color (0.0~1.0)
 */
static inline void C2D_SetImageTint(C2D_ImageTint* tint, C2D_Corner corner, u32 color, float blend)
{
	tint->corners[corner].color = color;
	tint->corners[corner].blend = blend;
}

/** @brief Configures an image tint structure with the specified tint parameters applied to all corners
 *  @param[in] tint Image tint structure
 *  @param[in] color RGB tint color and Alpha transparency
 *  @param[in] blend Blending strength of the tint color (0.0~1.0)
 */
static inline void C2D_PlainImageTint(C2D_ImageTint* tint, u32 color, float blend)
{
	C2D_SetImageTint(tint, C2D_TopLeft,  color, blend);
	C2D_SetImageTint(tint, C2D_TopRight, color, blend);
	C2D_SetImageTint(tint, C2D_BotLeft,  color, blend);
	C2D_SetImageTint(tint, C2D_BotRight, color, blend);
}

/** @brief Configures an image tint structure to just apply transparency to the image
 *  @param[in] tint Image tint structure
 *  @param[in] alpha Alpha transparency value to apply to the image
 */
static inline void C2D_AlphaImageTint(C2D_ImageTint* tint, float alpha)
{
	C2D_PlainImageTint(tint, C2D_Color32f(0.0f, 0.0f, 0.0f, alpha), 0.0f);
}

/** @brief Configures an image tint structure with the specified tint parameters applied to the top side (e.g. for gradients)
 *  @param[in] tint Image tint structure
 *  @param[in] color RGB tint color and Alpha transparency
 *  @param[in] blend Blending strength of the tint color (0.0~1.0)
 */
static inline void C2D_TopImageTint(C2D_ImageTint* tint, u32 color, float blend)
{
	C2D_SetImageTint(tint, C2D_TopLeft,  color, blend);
	C2D_SetImageTint(tint, C2D_TopRight, color, blend);
}

/** @brief Configures an image tint structure with the specified tint parameters applied to the bottom side (e.g. for gradients)
 *  @param[in] tint Image tint structure
 *  @param[in] color RGB tint color and Alpha transparency
 *  @param[in] blend Blending strength of the tint color (0.0~1.0)
 */
static inline void C2D_BottomImageTint(C2D_ImageTint* tint, u32 color, float blend)
{
	C2D_SetImageTint(tint, C2D_BotLeft,  color, blend);
	C2D_SetImageTint(tint, C2D_BotRight, color, blend);
}

/** @brief Configures an image tint structure with the specified tint parameters applied to the left side (e.g. for gradients)
 *  @param[in] tint Image tint structure
 *  @param[in] color RGB tint color and Alpha transparency
 *  @param[in] blend Blending strength of the tint color (0.0~1.0)
 */
static inline void C2D_LeftImageTint(C2D_ImageTint* tint, u32 color, float blend)
{
	C2D_SetImageTint(tint, C2D_TopLeft, color, blend);
	C2D_SetImageTint(tint, C2D_BotLeft, color, blend);
}

/** @brief Configures an image tint structure with the specified tint parameters applied to the right side (e.g. for gradients)
 *  @param[in] tint Image tint structure
 *  @param[in] color RGB tint color and Alpha transparency
 *  @param[in] blend Blending strength of the tint color (0.0~1.0)
 */
static inline void C2D_RightImageTint(C2D_ImageTint* tint, u32 color, float blend)
{
	C2D_SetImageTint(tint, C2D_TopRight, color, blend);
	C2D_SetImageTint(tint, C2D_BotRight, color, blend);
}

/** @} */

/** @defgroup Base Basic functions
 *  @{
 */

/** @brief Initialize citro2d
 *  @param[in] maxObjects Maximum number of 2D objects that can be drawn per frame.
 *  @remarks Pass C2D_DEFAULT_MAX_OBJECTS as a starting point.
 *  @returns true on success, false on failure
 */
bool C2D_Init(size_t maxObjects);

/** @brief Deinitialize citro2d */
void C2D_Fini(void);

/** @brief Prepares the GPU for rendering 2D content
 *  @remarks This needs to be done only once in the program if citro2d is the sole user of the GPU.
 */
void C2D_Prepare(void);

/** @brief Ensures all 2D objects so far have been drawn */
void C2D_Flush(void);

/** @brief Configures the size of the 2D scene.
 *  @param[in] width The width of the scene, in pixels.
 *  @param[in] height The height of the scene, in pixels.
 *  @param[in] tilt Whether the scene is tilted like the 3DS's sideways screens.
 */
void C2D_SceneSize(u32 width, u32 height, bool tilt);

/** @brief Configures the size of the 2D scene to match that of the specified render target.
 *  @param[in] target Render target
 */
static inline void C2D_SceneTarget(C3D_RenderTarget* target)
{
	C2D_SceneSize(target->frameBuf.width, target->frameBuf.height, target->linked);
}

/** @brief Resets the model transformation matrix. */
void C2D_ViewReset(void);

/** @brief Saves the current model transformation matrix.
 * @param[out] matrix Pointer to save the current matrix to
 */
void C2D_ViewSave(C3D_Mtx* matrix);

/** @brief Restores a previously saved model transformation matrix.
 * @param[in] matrix Pointer to matrix to restor
 */
void C2D_ViewRestore(const C3D_Mtx* matrix);

/** @brief Translates everything drawn via the model matrix.
 * @param[in] x Translation in the x direction
 * @param[in] y Translation in the y direction
 */
void C2D_ViewTranslate(float x, float y);

/** @brief Rotates everything drawn via the model matrix.
 * @param[in] rotation Rotation in the counterclockwise direction in radians
 */
void C2D_ViewRotate(float rotation);

/** @brief Rotates everything drawn via the model matrix.
 * @param[in] rotation Rotation in the counterclockwise direction in degrees
 */
static inline void C2D_ViewRotateDegrees(float rotation)
{
	C2D_ViewRotate(C3D_AngleFromDegrees(rotation));
}

/** @brief Shears everything drawn via the model matrix.
 * @param[in] x Shear factor in the x direction
 * @param[in] y Shear factor in the y direction
 */
void C2D_ViewShear(float x, float y);

/** @brief Scales everything drawn via the model matrix.
 * @param[in] x Scale factor in the x direction
 * @param[in] y Scale factor in the y direction
 */
void C2D_ViewScale(float x, float y);

/** @brief Helper function to create a render target for a screen
 *  @param[in] screen Screen (GFX_TOP or GFX_BOTTOM)
 *  @param[in] side Side (GFX_LEFT or GFX_RIGHT)
 *  @returns citro3d render target object
 */
C3D_RenderTarget* C2D_CreateScreenTarget(gfxScreen_t screen, gfx3dSide_t side);

/** @brief Helper function to clear a rendertarget using the specified color
 *  @param[in] target Render target to clear
 *  @param[in] color 32-bit RGBA color value to fill the target with
 */
void C2D_TargetClear(C3D_RenderTarget* target, u32 color);

/** @brief Helper function to begin drawing a 2D scene on a render target
 *  @param[in] target Render target to draw the 2D scene to
 */
static inline void C2D_SceneBegin(C3D_RenderTarget* target)
{
	C2D_Flush();
	C3D_FrameDrawOn(target);
	C2D_SceneTarget(target);
}

/** @} */

/** @defgroup Env Drawing environment functions
 *  @{
 */

/** @brief Configures the fading color
 *  @param[in] color 32-bit RGBA color value to be used as the fading color (0 by default)
 *  @remark The alpha component of the color is used as the strength of the fading color.
 *          If alpha is zero, the fading color has no effect. If it is the highest value,
 *          the rendered pixels will all have the fading color. Everything inbetween is
 *          rendered as a blend of the original pixel color and the fading color.
 */
bool C2D_Fade(u32 color);

/** @brief Configures the formula used to calculate the tinted texture color
 *  @param[in] mode Tinting mode
 *  @remark Texture tinting works by linearly interpolating between the regular texture color
 *          and the tinted texture color according to the blending strength parameter.
 *          This function can be used to change how the tinted texture color is precisely
 *          calculated, refer to \ref C2D_TintMode for a list of available tinting modes.
 */
bool C2D_SetTintMode(C2D_TintMode mode);

/** @} */

/** @defgroup Drawing Drawing functions
 *  @{
 */

/** @brief Draws an image using the GPU (variant accepting C2D_DrawParams)
 *  @param[in] img Handle of the image to draw
 *  @param[in] params Parameters with which to draw the image
 *  @param[in] tint Tint parameters to apply to the image (optional, can be null)
 *  @returns true on success, false on failure
 */
bool C2D_DrawImage(C2D_Image img, const C2D_DrawParams* params, const C2D_ImageTint* tint C2D_OPTIONAL(nullptr));

/** @brief Draws an image using the GPU (variant accepting position/scaling)
 *  @param[in] img Handle of the image to draw
 *  @param[in] x X coordinate at which to place the top left corner of the image
 *  @param[in] y Y coordinate at which to place the top left corner of the image
 *  @param[in] depth Depth value to draw the image with
 *  @param[in] tint Tint parameters to apply to the image (optional, can be null)
 *  @param[in] scaleX Horizontal scaling factor to apply to the image (optional, by default 1.0f); negative values apply a horizontal flip
 *  @param[in] scaleY Vertical scaling factor to apply to the image (optional, by default 1.0f); negative values apply a vertical flip
 */
static inline bool C2D_DrawImageAt(C2D_Image img, float x, float y, float depth,
	const C2D_ImageTint* tint C2D_OPTIONAL(nullptr),
	float scaleX C2D_OPTIONAL(1.0f), float scaleY C2D_OPTIONAL(1.0f))
{
	C2D_DrawParams params =
	{
		{ x, y, scaleX*img.subtex->width, scaleY*img.subtex->height },
		{ 0.0f, 0.0f },
		depth, 0.0f
	};
	return C2D_DrawImage(img, &params, tint);
}

/** @brief Draws an image using the GPU (variant accepting position/scaling/rotation)
 *  @param[in] img Handle of the image to draw
 *  @param[in] x X coordinate at which to place the center of the image
 *  @param[in] y Y coordinate at which to place the center of the image
 *  @param[in] depth Depth value to draw the image with
 *  @param[in] angle Angle (in radians) to rotate the image by, counter-clockwise
 *  @param[in] tint Tint parameters to apply to the image (optional, can be null)
 *  @param[in] scaleX Horizontal scaling factor to apply to the image (optional, by default 1.0f); negative values apply a horizontal flip
 *  @param[in] scaleY Vertical scaling factor to apply to the image (optional, by default 1.0f); negative values apply a vertical flip
 */
static inline bool C2D_DrawImageAtRotated(C2D_Image img, float x, float y, float depth, float angle,
	const C2D_ImageTint* tint C2D_OPTIONAL(nullptr),
	float scaleX C2D_OPTIONAL(1.0f), float scaleY C2D_OPTIONAL(1.0f))
{
	C2D_DrawParams params =
	{
		{ x, y, scaleX*img.subtex->width, scaleY*img.subtex->height },
		{ (scaleX*img.subtex->width)/2.0f, (scaleY*img.subtex->height)/2.0f },
		depth, angle
	};
	return C2D_DrawImage(img, &params, tint);
}

/** @brief Draws a plain triangle using the GPU
 *  @param[in] x0 X coordinate of the first vertex of the triangle
 *  @param[in] y0 Y coordinate of the first vertex of the triangle
 *  @param[in] clr0 32-bit RGBA color of the first vertex of the triangle
 *  @param[in] x1 X coordinate of the second vertex of the triangle
 *  @param[in] y1 Y coordinate of the second vertex of the triangle
 *  @param[in] clr1 32-bit RGBA color of the second vertex of the triangle
 *  @param[in] x2 X coordinate of the third vertex of the triangle
 *  @param[in] y2 Y coordinate of the third vertex of the triangle
 *  @param[in] clr2 32-bit RGBA color of the third vertex of the triangle
 *  @param[in] depth Depth value to draw the triangle with
 */
bool C2D_DrawTriangle(
	float x0, float y0, u32 clr0,
	float x1, float y1, u32 clr1,
	float x2, float y2, u32 clr2,
	float depth);

/** @brief Draws a plain line using the GPU
 *  @param[in] x0 X coordinate of the first vertex of the line
 *  @param[in] y0 Y coordinate of the first vertex of the line
 *  @param[in] clr0 32-bit RGBA color of the first vertex of the line
 *  @param[in] x1 X coordinate of the second vertex of the line
 *  @param[in] y1 Y coordinate of the second vertex of the line
 *  @param[in] clr1 32-bit RGBA color of the second vertex of the line
 *  @param[in] thickness Thickness, in pixels, of the line
 *  @param[in] depth Depth value to draw the line with
 */
bool C2D_DrawLine(
	float x0, float y0, u32 clr0,
	float x1, float y1, u32 clr1,
	float thickness, float depth);

/** @brief Draws a plain rectangle using the GPU
 *  @param[in] x X coordinate of the top-left vertex of the rectangle
 *  @param[in] y Y coordinate of the top-left vertex of the rectangle
 *  @param[in] z Z coordinate (depth value) to draw the rectangle with
 *  @param[in] w Width of the rectangle
 *  @param[in] h Height of the rectangle
 *  @param[in] clr0 32-bit RGBA color of the top-left corner of the rectangle
 *  @param[in] clr1 32-bit RGBA color of the top-right corner of the rectangle
 *  @param[in] clr2 32-bit RGBA color of the bottom-left corner of the rectangle
 *  @param[in] clr3 32-bit RGBA color of the bottom-right corner of the rectangle
 */
bool C2D_DrawRectangle(
	float x, float y, float z, float w, float h,
	u32 clr0, u32 clr1, u32 clr2, u32 clr3);

/** @brief Draws a plain rectangle using the GPU (with a solid color)
 *  @param[in] x X coordinate of the top-left vertex of the rectangle
 *  @param[in] y Y coordinate of the top-left vertex of the rectangle
 *  @param[in] z Z coordinate (depth value) to draw the rectangle with
 *  @param[in] w Width of the rectangle
 *  @param[in] h Height of the rectangle
 *  @param[in] clr 32-bit RGBA color of the rectangle
 */
static inline bool C2D_DrawRectSolid(
	float x, float y, float z, float w, float h,
	u32 clr)
{
	return C2D_DrawRectangle(x,y,z,w,h,clr,clr,clr,clr);
}

/** @brief Draws an ellipse using the GPU
 *  @param[in] x X coordinate of the top-left vertex of the ellipse
 *  @param[in] y Y coordinate of the top-left vertex of the ellipse
 *  @param[in] z Z coordinate (depth value) to draw the ellipse with
 *  @param[in] w Width of the ellipse
 *  @param[in] h Height of the ellipse
 *  @param[in] clr0 32-bit RGBA color of the top-left corner of the ellipse
 *  @param[in] clr1 32-bit RGBA color of the top-right corner of the ellipse
 *  @param[in] clr2 32-bit RGBA color of the bottom-left corner of the ellipse
 *  @param[in] clr3 32-bit RGBA color of the bottom-right corner of the ellipse
 *  @note Switching to and from "circle mode" internally requires an expensive state change. As such, the recommended usage of this feature is to draw all non-circular objects first, then draw all circular objects.
*/
bool C2D_DrawEllipse(
	float x, float y, float z, float w, float h,
	u32 clr0, u32 clr1, u32 clr2, u32 clr3);

/** @brief Draws a ellipse using the GPU (with a solid color)
 *  @param[in] x X coordinate of the top-left vertex of the ellipse
 *  @param[in] y Y coordinate of the top-left vertex of the ellipse
 *  @param[in] z Z coordinate (depth value) to draw the ellipse with
 *  @param[in] w Width of the ellipse
 *  @param[in] h Height of the ellipse
 *  @param[in] clr 32-bit RGBA color of the ellipse
 *  @note Switching to and from "circle mode" internally requires an expensive state change. As such, the recommended usage of this feature is to draw all non-circular objects first, then draw all circular objects.
*/
static inline bool C2D_DrawEllipseSolid(
	float x, float y, float z, float w, float h,
	u32 clr)
{
	return C2D_DrawEllipse(x,y,z,w,h,clr,clr,clr,clr);
}

/** @brief Draws a circle (an ellipse with identical width and height) using the GPU
 *  @param[in] x X coordinate of the center of the circle
 *  @param[in] y Y coordinate of the center of the circle
 *  @param[in] z Z coordinate (depth value) to draw the ellipse with
 *  @param[in] radius Radius of the circle
 *  @param[in] clr0 32-bit RGBA color of the top-left corner of the ellipse
 *  @param[in] clr1 32-bit RGBA color of the top-right corner of the ellipse
 *  @param[in] clr2 32-bit RGBA color of the bottom-left corner of the ellipse
 *  @param[in] clr3 32-bit RGBA color of the bottom-right corner of the ellipse
 *  @note Switching to and from "circle mode" internally requires an expensive state change. As such, the recommended usage of this feature is to draw all non-circular objects first, then draw all circular objects.
*/
static inline bool C2D_DrawCircle(
	float x, float y, float z, float radius,
	u32 clr0, u32 clr1, u32 clr2, u32 clr3)
{
	return C2D_DrawEllipse(
		x - radius,y - radius,z,radius*2,radius*2,
		clr0,clr1,clr2,clr3);
}

/** @brief Draws a circle (an ellipse with identical width and height) using the GPU (with a solid color)
 *  @param[in] x X coordinate of the center of the circle
 *  @param[in] y Y coordinate of the center of the circle
 *  @param[in] z Z coordinate (depth value) to draw the ellipse with
 *  @param[in] radius Radius of the circle
 *  @param[in] clr 32-bit RGBA color of the ellipse
 *  @note Switching to and from "circle mode" internally requires an expensive state change. As such, the recommended usage of this feature is to draw all non-circular objects first, then draw all circular objects.
*/
static inline bool C2D_DrawCircleSolid(
	float x, float y, float z, float radius,
	u32 clr)
{
	return C2D_DrawCircle(x,y,z,radius,clr,clr,clr,clr);
}
/** @} */