#ifndef __LIBRASHADER_H__
#define __LIBRASHADER_H__

#pragma once

#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#ifdef _WIN32 && RUNTIME_D3D11 
#include <d3d11.h>
#else
typedef void ID3D11Device; typedef void ID3D11RenderTargetView; typedef void ID3D1ShaderResourceView;
#endif

/// Error codes for librashader error types.
enum LIBRA_ERRNO
#ifdef __cplusplus
    : int32_t
#endif // __cplusplus
{
 LIBRA_ERRNO_UNKNOWN_ERROR = 0,
 LIBRA_ERRNO_INVALID_PARAMETER = 1,
 LIBRA_ERRNO_INVALID_PATH = 2,
 LIBRA_ERRNO_PRESET_ERROR = 3,
 LIBRA_ERRNO_PREPROCESS_ERROR = 4,
 LIBRA_ERRNO_RUNTIME_ERROR = 5,
};
#ifndef __cplusplus
typedef int32_t LIBRA_ERRNO;
#endif // __cplusplus

/// A Direct3D 11 filter chain.
typedef struct FilterChain FilterChain;

/// The error type for librashader.
typedef struct _libra_error _libra_error;

/// A shader preset including all specified parameters, textures, and paths to specified shaders.
///
/// A shader preset can be used to create a filter chain runtime instance, or reflected to get
/// parameter metadata.
typedef struct _shader_preset _shader_preset;

typedef struct _libra_error* libra_error_t;

typedef struct _shader_preset* libra_shader_preset_t;

#if defined(LIBRA_RUNTIME_OPENGL)
/// A GL function loader that librashader needs to be initialized with.
typedef const void* (*gl_loader_t)(const char*);
#endif

/// Options for Direct3D11 filter chain creation.
typedef struct FilterChainOptions {
    /// Use a deferred context to record shader rendering state.
    ///
    /// The deferred context will be executed on the immediate context
    /// with `RenderContextState = true`.
    bool use_deferred_context;
    /// Whether or not to explicitly disable mipmap
    /// generation regardless of shader preset settings.
    bool force_no_mipmaps;
} FilterChainOptions;

#if defined(LIBRA_RUNTIME_OPENGL)
typedef struct FilterChain* libra_gl_filter_chain_t;
#endif

#if defined(LIBRA_RUNTIME_OPENGL)
/// OpenGL parameters for the source image.
typedef struct libra_source_image_gl_t {
    /// A texture GLuint to the source image.
    uint32_t handle;
    /// The format of the source image.
    uint32_t format;
    /// The width of the source image.
    uint32_t width;
    /// The height of the source image.
    uint32_t height;
} libra_source_image_gl_t;
#endif

/// Parameters for the output viewport.
typedef struct libra_viewport_t {
    float x;
    float y;
    uint32_t width;
    uint32_t height;
} libra_viewport_t;

#if defined(LIBRA_RUNTIME_OPENGL)
/// OpenGL parameters for the output framebuffer.
typedef struct libra_draw_framebuffer_gl_t {
    /// A framebuffer GLuint to the output framebuffer.
    uint32_t handle;
    /// A texture GLuint to the logical buffer of the output framebuffer.
    uint32_t texture;
    /// The format of the output framebuffer.
    uint32_t format;
} libra_draw_framebuffer_gl_t;
#endif

/// Options for each Direct3D11 shader frame.
typedef struct FrameOptions {
    /// Whether or not to clear the history buffers.
    bool clear_history;
    /// The direction of the frame. 1 should be vertical.
    int32_t frame_direction;
} FrameOptions;

#if defined(LIBRA_RUNTIME_D3D11)
typedef struct FilterChain* libra_d3d11_filter_chain_t;
#endif

#if defined(LIBRA_RUNTIME_D3D11)
/// OpenGL parameters for the source image.
typedef struct libra_source_image_d3d11_t {
    /// A shader resource view into the source image
    const ID3D11ShaderResourceView* handle;
    /// The width of the source image.
    uint32_t width;
    /// The height of the source image.
    uint32_t height;
} libra_source_image_d3d11_t;
#endif

typedef libra_error_t(*PFN_libra_preset_free)(libra_shader_preset_t* preset);

typedef libra_error_t(*PFN_libra_preset_set_param)(libra_shader_preset_t* preset,
    const char* name,
    float value);

typedef libra_error_t(*PFN_libra_preset_get_param)(libra_shader_preset_t* preset,
    const char* name,
    float* value);

typedef libra_error_t(*PFN_libra_preset_print)(libra_shader_preset_t* preset);

typedef libra_error_t(*PFN_libra_preset_get_runtime_param_names)(libra_shader_preset_t* preset,
    const char** value);

typedef LIBRA_ERRNO(*PFN_libra_error_errno)(libra_error_t error);

typedef int32_t(*PFN_libra_error_print)(libra_error_t error);

typedef int32_t(*PFN_libra_error_free)(libra_error_t* error);

typedef int32_t(*PFN_libra_error_write)(libra_error_t error, char** out);

typedef int32_t(*PFN_libra_error_free_string)(char** out);

#if defined(LIBRA_RUNTIME_OPENGL)
typedef libra_error_t(*PFN_libra_gl_init_context)(gl_loader_t loader);
#endif

#if defined(LIBRA_RUNTIME_OPENGL)
typedef libra_error_t(*PFN_libra_gl_filter_chain_create)(libra_shader_preset_t* preset,
    const struct FilterChainOptions* options,
    libra_gl_filter_chain_t* out);
#endif

#if defined(LIBRA_RUNTIME_OPENGL)
typedef libra_error_t(*PFN_libra_gl_filter_chain_frame)(libra_gl_filter_chain_t* chain,
    size_t frame_count,
    struct libra_source_image_gl_t image,
    struct libra_viewport_t viewport,
    struct libra_draw_framebuffer_gl_t out,
    const float* mvp,
    const struct FrameOptions* opt);
#endif

#if defined(LIBRA_RUNTIME_OPENGL)
typedef libra_error_t(*PFN_libra_gl_filter_chain_free)(libra_gl_filter_chain_t* chain);
#endif

#if defined(LIBRA_RUNTIME_D3D11)
typedef libra_error_t(*PFN_libra_d3d11_filter_chain_create)(libra_shader_preset_t* preset,
    const struct FilterChainOptions* options,
    const ID3D11Device* device,
    libra_d3d11_filter_chain_t* out);
#endif

#if defined(LIBRA_RUNTIME_D3D11)
typedef libra_error_t(*PFN_libra_d3d11_filter_chain_frame)(libra_d3d11_filter_chain_t* chain,
    size_t frame_count,
    struct libra_source_image_d3d11_t image,
    struct libra_viewport_t viewport,
    const ID3D11RenderTargetView* out,
    const float* mvp,
    const struct FrameOptions* opt);
#endif

#if defined(LIBRA_RUNTIME_D3D11)
typedef libra_error_t(*PFN_libra_d3d11_filter_chain_free)(libra_d3d11_filter_chain_t* chain);
#endif

#ifdef __cplusplus
extern "C" {
#endif // __cplusplus

    /// Get the error code corresponding to this error object.
    ///
    /// ## Safety
    ///   - `error` must be valid and initialized.
    LIBRA_ERRNO libra_error_errno(libra_error_t error);

    /// Print the error message.
    ///
    /// If `error` is null, this function does nothing and returns 1. Otherwise, this function returns 0.
    /// ## Safety
    ///   - `error` must be a valid and initialized instance of `libra_error_t`.
    int32_t libra_error_print(libra_error_t error);

    /// Frees any internal state kept by the error.
    ///
    /// If `error` is null, this function does nothing and returns 1. Otherwise, this function returns 0.
    /// The resulting error object becomes null.
    /// ## Safety
    ///   - `error` must be null or a pointer to a valid and initialized instance of `libra_error_t`.
    int32_t libra_error_free(libra_error_t* error);

    /// Writes the error message into `out`
    ///
    /// If `error` is null, this function does nothing and returns 1. Otherwise, this function returns 0.
    /// ## Safety
    ///   - `error` must be a valid and initialized instance of `libra_error_t`.
    ///   - `out` must be a non-null pointer. The resulting string must not be modified.
    int32_t libra_error_write(libra_error_t error,
        char** out);

    /// Frees an error string previously allocated by `libra_error_write`.
    ///
    /// After freeing, the pointer will be set to null.
    /// ## Safety
    ///   - If `libra_error_write` is not null, it must point to a string previously returned by `libra_error_write`.
    ///     Attempting to free anything else, including strings or objects from other librashader functions, is immediate
    ///     Undefined Behaviour.
    int32_t libra_error_free_string(char** out);

    /// Load a preset.
    ///
    /// ## Safety
    ///  - `filename` must be either null or a valid, aligned pointer to a string path to the shader preset.
    ///  - `out` must be either null, or an aligned pointer to an uninitialized or invalid `libra_shader_preset_t`.
    /// ## Returns
    ///  - If any parameters are null, `out` is unchanged, and this function returns `LIBRA_ERR_INVALID_PARAMETER`.
    libra_error_t libra_preset_create(const char* filename,
        libra_shader_preset_t* out);

    /// Free the preset.
    ///
    /// If `preset` is null, this function does nothing. The resulting value in `preset` then becomes
    /// null.
    ///
    /// ## Safety
    /// - `preset` must be a valid and aligned pointer to a shader preset.
    libra_error_t libra_preset_free(libra_shader_preset_t* preset);

    /// Set the value of the parameter in the preset.
    ///
    /// ## Safety
    /// - `preset` must be null or a valid and aligned pointer to a shader preset.
    /// - `name` must be null or a valid and aligned pointer to a string.
    libra_error_t libra_preset_set_param(libra_shader_preset_t* preset, const char* name, float value);

    /// Get the value of the parameter as set in the preset.
    ///
    /// ## Safety
    /// - `preset` must be null or a valid and aligned pointer to a shader preset.
    /// - `name` must be null or a valid and aligned pointer to a string.
    /// - `value` may be a pointer to a uninitialized `float`.
    libra_error_t libra_preset_get_param(libra_shader_preset_t* preset, const char* name, float* value);

    /// Pretty print the shader preset.
    ///
    /// ## Safety
    /// - `preset` must be null or a valid and aligned pointer to a shader preset.
    libra_error_t libra_preset_print(libra_shader_preset_t* preset);

    /// Get a list of runtime parameter names.
    ///
    /// The returned value can not currently be freed.
    /// This function should be considered in progress. Its use is discouraged.
    libra_error_t libra_preset_get_runtime_param_names(libra_shader_preset_t* preset,
        const char** value);

#if defined(LIBRA_RUNTIME_OPENGL)
    /// Initialize the OpenGL Context for librashader.
    ///
    /// ## Safety
    /// Attempting to create a filter chain will fail.
    ///
    /// Reinitializing the OpenGL context with a different loader immediately invalidates previous filter
    /// chain objects, and drawing with them causes immediate undefined behaviour.
    libra_error_t libra_gl_init_context(gl_loader_t loader);
#endif

#if defined(LIBRA_RUNTIME_OPENGL)
    /// Create the filter chain given the shader preset.
    ///
    /// The shader preset is immediately invalidated and must be recreated after
    /// the filter chain is created.
    ///
    /// ## Safety:
    /// - `preset` must be either null, or valid and aligned.
    /// - `options` must be either null, or valid and aligned.
    /// - `out` must be aligned, but may be null, invalid, or uninitialized.
    libra_error_t libra_gl_filter_chain_create(libra_shader_preset_t* preset,
        const struct FilterChainOptions* options,
        libra_gl_filter_chain_t* out);
#endif

#if defined(LIBRA_RUNTIME_OPENGL)
    /// Draw a frame with the given parameters for the given filter chain.
    ///
    /// ## Safety
    /// - `chain` may be null, invalid, but not uninitialized. If `chain` is null or invalid, this
    ///    function will return an error.
    /// - `mvp` may be null, or if it is not null, must be an aligned pointer to 16 consecutive `float`
    ///    values for the model view projection matrix.
    /// - `opt` may be null, or if it is not null, must be an aligned pointer to a valid `frame_gl_opt_t`
    ///    struct.
    libra_error_t libra_gl_filter_chain_frame(libra_gl_filter_chain_t* chain,
        size_t frame_count,
        struct libra_source_image_gl_t image,
        struct libra_viewport_t viewport,
        struct libra_draw_framebuffer_gl_t out,
        const float* mvp,
        const struct FrameOptions* opt);
#endif

#if defined(LIBRA_RUNTIME_OPENGL)
    /// Free a GL filter chain.
    ///
    /// The resulting value in `chain` then becomes null.
    /// ## Safety
    /// - `chain` must be either null or a valid and aligned pointer to an initialized `libra_gl_filter_chain_t`.
    libra_error_t libra_gl_filter_chain_free(libra_gl_filter_chain_t* chain);
#endif

#if defined(LIBRA_RUNTIME_D3D11)
    /// Create the filter chain given the shader preset.
    ///
    /// The shader preset is immediately invalidated and must be recreated after
    /// the filter chain is created.
    ///
    /// ## Safety:
    /// - `preset` must be either null, or valid and aligned.
    /// - `options` must be either null, or valid and aligned.
    /// - `out` must be aligned, but may be null, invalid, or uninitialized.
    libra_error_t libra_d3d11_filter_chain_create(libra_shader_preset_t* preset,
        const struct FilterChainOptions* options,
        const ID3D11Device* device,
        libra_d3d11_filter_chain_t* out);
#endif

#if defined(LIBRA_RUNTIME_D3D11)
    /// Draw a frame with the given parameters for the given filter chain.
    ///
    /// ## Safety
    /// - `chain` may be null, invalid, but not uninitialized. If `chain` is null or invalid, this
    ///    function will return an error.
    /// - `mvp` may be null, or if it is not null, must be an aligned pointer to 16 consecutive `float`
    ///    values for the model view projection matrix.
    /// - `opt` may be null, or if it is not null, must be an aligned pointer to a valid `frame_gl_opt_t`
    ///    struct.
    libra_error_t libra_d3d11_filter_chain_frame(libra_d3d11_filter_chain_t* chain,
        size_t frame_count,
        struct libra_source_image_d3d11_t image,
        struct libra_viewport_t viewport,
        const ID3D11RenderTargetView* out,
        const float* mvp,
        const struct FrameOptions* opt);
#endif

#if defined(LIBRA_RUNTIME_D3D11)
    /// Free a D3D11 filter chain.
    ///
    /// The resulting value in `chain` then becomes null.
    /// ## Safety
    /// - `chain` must be either null or a valid and aligned pointer to an initialized `libra_d3d11_filter_chain_t`.
    libra_error_t libra_d3d11_filter_chain_free(libra_d3d11_filter_chain_t* chain);
#endif

#ifdef __cplusplus
} // extern "C"
#endif // __cplusplus

#endif /* __LIBRASHADER_H__ */