/*
 * TODO:
 * 	- add some sweet unit models
 *    - need to add indexed drawing for assimp models
 * 	- map generation
 * 	- pathfinding
 *  - update imgui to v1.62 -- requires changes to example api
 */

// Some defaults for the game layout
#define HEX_SIZE 10
#define HEX_RADIUS 19
#define HEX_ORIENTATION layout_flat
#define FILL_COLOR 0x565656FF
#define SELECTED_FILL_COLOR 0xF46000FF
#define DEBUG_DRAW true
#define VIEWPORT_WIDTH 1280
#define VIEWPORT_HEIGHT 720
#define CONE_ANGLE 30


#include <vector>

#if defined(_WIN32)
	#include <windows.h>
	#include <Winuser.h>
	#include <SDL.h>
#else
	#include <SDL2/SDL.h>
#endif

#include <SDL_image.h>

#include "aixlog.hpp"

#include "hexgame.h"
#include "hexlib.h"
#include "renderer.h"
#include "gooey.h"
#include "mesh.h"

using std::vector;

game_state* g_game_state;
render_state* g_render_state;
vector<Point> g_polygon_select_vertices = {Point(), Point(), Point(), Point()};

void
createHexes(vector<hex_info> *hxi_array, const Layout &layout, uint32 color)
{
	// create a hexagonal grid of hexagons
	int map_radius = HEX_RADIUS;
	for (int q = -map_radius; q <= map_radius; q++)
	{
		int r1 = std::max(-map_radius, -q - map_radius);
		int r2 = std::min(map_radius, -q + map_radius);
		
		for (int r = r1; r <= r2; r++)
		{
			hex_info hxi;
			hxi.hexID = (int32) hxi_array->size();
			hxi.hex.q = q; hxi.hex.r = r; hxi.hex.s = -q-r;
			Point p = hex_to_pixel(layout, hxi.hex);
			hxi.XPos = p.x;
			hxi.YPos = p.y;
			hxi.current_color = color;
			hxi.stored_color = color;
			hxi.vertices = polygon_corners(layout, hxi.hex);
			hxi.vertices.shrink_to_fit();
			hxi_array->push_back(hxi);
		}
	}
}

v2i
mapMouseToViewport(int32 x, int32 y)
{
	v2i coords;
	coords.x = x;
	coords.y = g_render_state->viewport_dims.y - y;
	return coords;
}

void
resetHexes()
{
	g_game_state->start_hex = g_game_state->current_hex = 0;
	
	for (hex_info &hxi : *g_game_state->hex_array)
	{
		hxi.selected = false;
		hxi.current_color = hxi.stored_color;
	}
}

hex_info *
getSingleHex(int32 x, int32 y)
{
	v2i dims = g_render_state->viewport_dims;
	v2f v = getUnprojectedCoords(x, y, dims.x, dims.y);
	Point p(v.x, v.y);
	Hex h = hex_round(pixel_to_hex(g_game_state->hex_layout, p));
	
	for (hex_info &hxi : *g_game_state->hex_array)
	{
		if (hex_equal(h, hxi.hex))
			return &hxi;
	}
	
	return 0;
}

void
setStartHex(hex_info *hex)
{
	hex->selected = true;
	hex->current_color = g_render_state->selected_fill_color;
	g_game_state->start_hex = g_game_state->current_hex = hex;
	g_game_state->is_selecting = true;
}

void
startDrawHelper(int32 x, int32 y)
{
	resetHexes();
	hex_info *hex = getSingleHex(x, y);
	if (hex)
		setStartHex(hex);
}

void
updateHexFill(int32 x, int32 y)
{
	hex_info *hxi = getSingleHex(x, y);
	if (hxi && (hxi != g_game_state->current_hex) && g_game_state->start_hex)
	{
		g_game_state->current_hex = hxi;
		int l = hex_distance(g_game_state->start_hex->hex, g_game_state->current_hex->hex);
		
		for (hex_info &h : *g_game_state->hex_array)
		{
			if (hex_distance(g_game_state->start_hex->hex, h.hex) <= l)
			{
				h.selected = true;
				h.current_color = g_render_state->selected_fill_color;
			}
			else
			{
				h.selected = false;
				h.current_color = h.stored_color;
			}
		}
	}
}

void
updateHexLineDraw(int32 x, int32 y)
{
	hex_info *hxi = getSingleHex(x, y);
	if (hxi && (hxi != g_game_state->current_hex) && g_game_state->start_hex)
	{
		g_game_state->current_hex = hxi;
		vector<Hex> hexLine = hex_linedraw(g_game_state->start_hex->hex, hxi->hex);
		
		for (hex_info &h1 : *g_game_state->hex_array)
		{
			for (uint i = 0; i < hexLine.size(); i++)
			{	
				Hex h2 = hexLine[i];
				if (hex_equal(h1.hex, h2))
				{
					h1.selected = true;
					h1.current_color = g_render_state->selected_fill_color;
					break;
				}
				else if (i == hexLine.size() - 1)
				{
					h1.selected = false;
					h1.current_color = h1.stored_color;
				}
			}
		}
	}
}

void
updateHexConeFill(int32 x, int32 y)
{
	hex_info *hxi = getSingleHex(x, y);
	if (hxi && (hxi != g_game_state->current_hex) && g_game_state->start_hex)
	{
		g_game_state->current_hex = hxi;
		vector<Hex> hexes = hex_conefill(g_game_state->start_hex->hex, hxi->hex);
		
		// TODO: Remove debug code here and from gooey.h
		Point p1(g_game_state->start_hex->XPos, g_game_state->start_hex->YPos);
		Point p2(g_game_state->current_hex->XPos, g_game_state->current_hex->YPos);
		real64 angle = std::atan2(p2.y - p1.y, p2.x - p1.x);
		real64 len = std::hypot(p2.y - p1.y, p2.x - p1.x);
		real64 coneAngle = CONE_ANGLE * M_PI / 180; // M_PI is non-standard and may not be portable
		
		real64 x1 = len * std::cos(angle);
		real64 y1 = len * std::sin(angle);
		// top of cone
		real64 topX = x1 * std::cos(coneAngle) - y1 * std::sin(coneAngle) + p1.x;
		real64 topY = x1 * std::sin(coneAngle) + y1 * std::cos(coneAngle) + p1.y;
		// bottom of cone
		real64 botX = x1 * std::cos(coneAngle) + y1 * std::sin(coneAngle) + p1.x;
		real64 botY = x1 * std::sin(-1 * coneAngle) + y1 * std::cos(coneAngle) + p1.y;

		Point test_p;
		Point vert2 = Point(botX, botY);
		Point vert4 = Point(topX, topY);
		std::vector<Point> vertices = {p1, vert2, p2, vert4};

		for (hex_info &h : *g_game_state->hex_array)
		{
			test_p.x = h.XPos;
			test_p.y = h.YPos;

			if (crossingTest(vertices, test_p))
			{
				h.selected = true;
				h.current_color = g_render_state->selected_fill_color;
			}
			else
			{
				h.selected = false;
				h.current_color = h.stored_color;
			}
		}

		g_polygon_select_vertices[0].x = p1.x; g_polygon_select_vertices[0].y = p1.y;
		g_polygon_select_vertices[1].x = vert2.x; g_polygon_select_vertices[1].y = vert2.y;
		g_polygon_select_vertices[2].x = p2.x; g_polygon_select_vertices[2].y = p2.y;
		g_polygon_select_vertices[3].x = vert4.x; g_polygon_select_vertices[3].y = vert4.y;
	}
}

void
handleMouseDown(SDL_MouseButtonEvent &e)
{
	v2i coords = mapMouseToViewport(e.x, e.y);

	switch (g_game_state->draw_mode)
	{
		case FILL:
			startDrawHelper(coords.x, coords.y);
			break;
		
		case LINE:
			startDrawHelper(coords.x, coords.y);
			break;
		
		case CONE_FILL:
			startDrawHelper(coords.x, coords.y);
			break;
		
		case PATHFINDING:
			break;
		
		case NONE:
			// fall through
		default:
		{
			hex_info *hex = getSingleHex(coords.x, coords.y);
			if (hex)
			{
				hex->selected = !hex->selected;
				if (hex->selected)
				{
					hex->current_color = g_render_state->selected_fill_color;
				}
				else
				{
					hex->current_color = hex->stored_color;
				}	
			}
		}break;
	}
}

void
handleMouseMove(SDL_MouseMotionEvent &e)
{
	v2i coords = mapMouseToViewport(e.x, e.y);
	
	switch (g_game_state->draw_mode)
	{
		case FILL:
			updateHexFill(coords.x, coords.y);
			break;
		
		case LINE:
			updateHexLineDraw(coords.x, coords.y);
			break;
		
		case CONE_FILL:
			updateHexConeFill(coords.x, coords.y);
			break;
		
		case PATHFINDING:
			break;
		
		case NONE:
			// fall through
		default:
			break;
	}
}

void
handleMouseUp(SDL_MouseButtonEvent &e)
{
	//v2i coords = mapMouseToViewport(e.x, e.y);
	
	switch (g_game_state->draw_mode)
	{
		case FILL:
			g_game_state->is_selecting = false;
			break;
		
		case LINE:
			g_game_state->is_selecting = false;
			break;
		
		case CONE_FILL:
			g_game_state->is_selecting = false;
			break;
		
		case PATHFINDING:
			break;
		
		case NONE:
			// fall through
		default:
			break;
	}
}

bool
processSDLEvents()
{
	SDL_Event e;
	bool run = true;

	while (SDL_PollEvent(&e))
	{
		// let gooey have event
		// TODO: need to check for both io.WantCaptureKeyboard and io.WantCaptureMouse
		// 	to fix bug with 'ESC' not passing through while in imgui
		bool gooey_wants =  gooeyProcessEvent(e);
		game_state* g = g_game_state;

		switch (e.type)
		{
			case SDL_QUIT:
				run = false;
				break;
			case SDL_KEYDOWN:
				switch (e.key.keysym.sym)
				{
					case SDLK_ESCAPE: run = false; break;
					case SDLK_e: g->is_moveforward = true; break;
					case SDLK_s: g->is_moveleft = true; break;
					case SDLK_d: g->is_movebackward = true; break;
					case SDLK_f: g->is_moveright = true; break;
					case SDLK_SPACE: g->is_moveup = true; break;
					case SDLK_c: g->is_movedown = true; break;
					case SDLK_r: g->is_rotateCW = true; break;
					case SDLK_w: g->is_rotateCCW = true; break;
				}
				break;
			case SDL_KEYUP:
				switch (e.key.keysym.sym)
				{
					case SDLK_e: g->is_moveforward = false; break;
					case SDLK_s: g->is_moveleft = false; break;
					case SDLK_d: g->is_movebackward = false; break;
					case SDLK_f: g->is_moveright = false; break;
					case SDLK_SPACE: g->is_moveup = false; break;
					case SDLK_c: g->is_movedown = false; break;
					case SDLK_r: g->is_rotateCW = false; break;
					case SDLK_w: g->is_rotateCCW = false; break;
				}
				break;
			case SDL_MOUSEBUTTONDOWN:
				if (!gooey_wants)
				{
					if (e.button.button == SDL_BUTTON_LEFT)
					{
						g->is_selecting = true;
						handleMouseDown(e.button);
					}
					else if (e.button.button == SDL_BUTTON_RIGHT)
					{
						g->is_camera_rotate = true;
					}
				}
				break;
			case SDL_MOUSEBUTTONUP:
				if (!gooey_wants)
				{
					if (e.button.button == SDL_BUTTON_LEFT)
					{
						g->is_selecting = false;
						handleMouseUp(e.button);
					}
					else if (e.button.button == SDL_BUTTON_RIGHT)
					{
						g->is_camera_rotate = false;
					}
				}
				break;
			case SDL_MOUSEMOTION:
				if (!gooey_wants && g->is_selecting)
					handleMouseMove(e.motion);
				else if(!gooey_wants && g->is_camera_rotate)
					rotateCamera(e.motion.xrel, e.motion.yrel);
				break;
			default:
				break;
		}
	}
		
	return run;
}

bool
cleanUp(SDL_Handles &handles)
{
	shutdownGooey();
	freeBuffers();	// renderer.h
	for (SDL_Surface *surface : handles.texSurfaces)
			SDL_FreeSurface(surface);
	shutdownAssimp(); // mesh.h
	IMG_Quit();	// SDL_image
	SDL_GL_DeleteContext(handles.glContext);
	SDL_DestroyWindow(handles.window);
	SDL_Quit();

	if (g_game_state)
	{
		if (g_game_state->hex_array)
			delete g_game_state->hex_array;
		delete g_game_state;
	}

	// TODO: C-style memory management for entities
	render_state* r = g_render_state;
	if (r) {
		// delete entities
		for (uint i = 0; i < r->entity_count; i++) {
			std::free(r->entities[i].vertices);
			r->entities[i].vertices = nullptr;
			std::free(r->entities[i].indices);
			r->entities[i].indices = nullptr;
		}

		std::free(r->entities);
		r->entities = nullptr;
		delete r;
		r = nullptr;
	}

	return true;
}

#if defined(_WIN32)
int CALLBACK WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
					 LPSTR lpCmdLine, int nShowCmd)
#else
int main(int argc, char* argv[])
#endif
{
	AixLog::Log::init<AixLog::SinkCout>(AixLog::Severity::trace, AixLog::Type::normal);
	LOG(INFO) << "Application started\n";

	// init global game state
	Layout layout(HEX_ORIENTATION, Point(HEX_SIZE, HEX_SIZE), Point(VIEWPORT_WIDTH / 2, VIEWPORT_HEIGHT / 2));
	g_game_state = new game_state(layout);
	g_game_state->hex_array = new vector<hex_info>;
	g_game_state->is_selecting = false;
	g_game_state->start_hex = 0x0;
	g_game_state->current_hex = 0x0;
	g_game_state->draw_mode = CONE_FILL;

	// init global render state
	g_render_state = new render_state();
	g_render_state->is_debug_draw = DEBUG_DRAW;
	g_render_state->viewport_dims = v2i(VIEWPORT_WIDTH, VIEWPORT_HEIGHT);
	g_render_state->fill_color = FILL_COLOR;
	g_render_state->selected_fill_color = SELECTED_FILL_COLOR;


	createHexes(g_game_state->hex_array, g_game_state->hex_layout, g_render_state->fill_color);
	SDL_Handles handles;
	
	if (SDL_Init(SDL_INIT_VIDEO) != 0)
	{
		LOG(ERROR) << "Error, SDL_Init: " << SDL_GetError() << "\n";
		return 1;
	}

	if (!initRenderer(handles, g_render_state->viewport_dims))
	{
		LOG(ERROR) << "Unable to initialize graphics, exiting\n";
		return 1;
	}

	{
		// load support for the JPG and PNG image formats
		int flags=IMG_INIT_JPG|IMG_INIT_PNG;
		int initted=IMG_Init(flags);
		if((initted&flags) != flags)
		{
			LOG(ERROR) << "IMG_Init: Failed to init required jpg and png support!\n";
			LOG(ERROR) << "IMG_Init: " << IMG_GetError() << "\n";
			return 1;
		}

		// pre-load textures
		const char * path = "../data/coords.layout.flat.png";
		if (!addTexture(handles, path))
		{
			LOG(ERROR) << "Error adding " << path << "\n";
			return 1;
		}
	}

	if (!initAssimp())
	{
		LOG(ERROR) << "Error initializing assimp\n";
		return 1;
	}

	{
		// TODO: keep better track of entity memory
		Entity* e = (Entity*) std::calloc(1, sizeof(Entity));
		e->num_vertices = getVertexCount();
		e->num_indices = getIndexCount();
		e->vertices = (glm::vec3 *) std::calloc(e->num_vertices, sizeof(glm::vec3));
		e->indices = (uint *) std::calloc(e->num_indices, sizeof(uint));
		convertMesh(e);
		g_render_state->entities = e;
		g_render_state->entity_count++;
	}
	
	if (!createScene(g_game_state->hex_array, g_render_state->entities, g_render_state->entity_count))
	{
		LOG(ERROR) << "Error in vertex data, exiting\n";
		return 1;
	}

	if (!initGooey(handles, g_render_state->viewport_dims))
	{
		LOG(ERROR) << "Fooey, No Gooey!\n";
		return 1;
	}
	
	// main loop
	while (processSDLEvents())
	{
		// TODO: remove hack to not peg CPU. replace with an actual frame timer
		SDL_Delay(16);	// ~60hz
		game_state* g = g_game_state;
		render_state* r = g_render_state;
		moveCamera(g->is_moveup, g->is_moveleft, g->is_movedown, g->is_moveright,
				g->is_moveforward, g->is_movebackward);
		rollCamera(g->is_rotateCW, g->is_rotateCCW);
		renderFrame(g->hex_array);
		if (r->is_debug_draw && g->draw_mode == CONE_FILL)
			renderDebug(g_polygon_select_vertices);
		renderGooey(handles, g->draw_mode, r->is_debug_draw, g->start_hex,
					g->current_hex, g->is_selecting);
		SDL_GL_SwapWindow(handles.window);
	}

	cleanUp(handles);
	LOG(INFO) << "Application exiting\n";
	return 0;
}