/**
 * Viewport Server - Shared Memory Framebuffer Export for Blender Integration
 * 
 * This module provides headless rendering with framebuffer export via shared memory
 * for integration with Blender's viewport as an external render engine.
 * 
 * Protocol:
 * - RunT renders to offscreen render target
 * - Pixels are exported to shared memory each frame
 * - Blender Python addon reads shared memory and displays in viewport
 */

#ifndef VIEWPORT_SERVER_H
#define VIEWPORT_SERVER_H

#include <stdint.h>
#include <stdbool.h>

#ifdef __cplusplus
extern "C" {
#endif

#define INPUT_EVENT_NONE        0
#define INPUT_EVENT_MOUSE_MOVE  1
#define INPUT_EVENT_MOUSE_DOWN  2
#define INPUT_EVENT_MOUSE_UP    3
#define INPUT_EVENT_KEY_DOWN    4
#define INPUT_EVENT_KEY_UP      5
#define INPUT_EVENT_MOUSE_WHEEL 6

#define MOUSE_BUTTON_LEFT   0
#define MOUSE_BUTTON_RIGHT  1
#define MOUSE_BUTTON_MIDDLE 2

#define MAX_INPUT_EVENTS 32

#pragma pack(push, 1)
typedef struct {
    uint8_t type;       // INPUT_EVENT_* type
    uint8_t button;     // mouse button or key code
    int16_t x;          // mouse X position or delta
    int16_t y;          // mouse Y position or delta
    int16_t delta;      // scroll wheel delta
    uint32_t modifiers; // shift/ctrl/alt flags
} InputEvent;
#pragma pack(pop)

// shared memory header structure must match Python end
#pragma pack(push, 1)
typedef struct {
    uint32_t magic;           // 0x52554E54 = 'RUNT'
    uint32_t version;         // protocol version (2)
    uint32_t width;           // current frame width
    uint32_t height;          // current frame height
    uint64_t frame_id;        // incrementing frame counter
    uint32_t ready_flag;      // 1 = new frame ready, 0 = consumed by blender
    uint32_t format;          // 0 = RGBA8, 1 = BGRA8
    uint32_t viewport_width;  // requested viewport width from Blender
    uint32_t viewport_height; // requested viewport height from Blender
    uint32_t resize_request;  // 1 = blender requests resize
    uint32_t shutdown_flag;   // 1 = blender requests shutdown
    uint32_t input_enabled;   // 1 = blender is capturing input for RunT
    float view_matrix[16];    // view matrix from blender column-major
    float proj_matrix[16];    // projection matrix from blender column-major
    // camera output from RunT to Blender bidirectional sync
    float runt_camera_pos[3]; // camera position from RunT (x, y, z)
    float runt_camera_rot[4]; // camera rotation from RunT quaternion: x, y, z, w
    uint32_t runt_camera_dirty; // 1 = RunT updated camera, 0 = consumed by blender
    // input event queue from blender to RunT
    uint32_t input_write_idx; // write index Blender increments
    uint32_t input_read_idx;  // read index RunT increments
    InputEvent input_events[MAX_INPUT_EVENTS]; // ring buffer of input events
    // pixel data follows header width * height * 4 bytes for RGBA8
} SharedFramebufferHeader;
#pragma pack(pop)

#define VIEWPORT_MAGIC 0x52554E54
#define VIEWPORT_VERSION 2
#define VIEWPORT_HEADER_SIZE sizeof(SharedFramebufferHeader)

// default shared memory name
#define VIEWPORT_SHMEM_NAME "RUNT_VIEWPORT_FB"

#define VIEWPORT_MAX_WIDTH 4096
#define VIEWPORT_MAX_HEIGHT 4096

// viewport server state
typedef struct {
    bool enabled;
    bool initialized;
    int width;
    int height;
    char shmem_name[256];
    uint64_t frame_count;
    void* render_target;      // kinc_g4_render_target_t*
    uint8_t* pixel_buffer;    // CPU-side pixel buffer
    void* shmem_handle;       // platform-specific handle
    void* shmem_ptr;          // mapped memory pointer
    size_t shmem_size;        // total shared memory size
} ViewportServerState;

bool viewport_server_init(const char* shmem_name, int width, int height);
void viewport_server_shutdown(void);
bool viewport_server_is_enabled(void);
void viewport_server_begin_frame(void);
void viewport_server_end_frame(void);
bool viewport_server_check_resize(int* new_width, int* new_height);
bool viewport_server_resize(int new_width, int new_height);
bool viewport_server_check_shutdown(void);
bool viewport_server_get_view_matrix(float* matrix);
bool viewport_server_get_proj_matrix(float* matrix);
ViewportServerState* viewport_server_get_state(void);
void viewport_server_set_camera(float pos_x, float pos_y, float pos_z, float rot_x, float rot_y, float rot_z, float rot_w);
bool viewport_server_read_input(InputEvent* event);

bool viewport_server_input_enabled(void);

#ifdef __cplusplus
}
#endif

#endif