/* Copyright (C) 2019  C. McEnroe <june@causal.agency>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <SDL.h>
#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include "cards.h"
#include "stack.h"

typedef unsigned uint;

enum {
	Stock,
	Waste1,
	Waste3,
	Foundation1,
	Foundation2,
	Foundation3,
	Foundation4,
	Tableau1,
	Tableau2,
	Tableau3,
	Tableau4,
	Tableau5,
	Tableau6,
	Tableau7,
	StacksLen,
};

static struct Stack stacks[StacksLen];

// TODO: Scoring method, score, time.
static struct {
	uint draw;
} game = {
	.draw = 3,
};

typedef void StackFn(struct Stack *dst, struct Stack *src, Uint8 len);

static struct {
	StackFn *fn;
	uint dst;
	uint src;
	uint len;
} undo;

static void gameDo(StackFn *fn, uint dst, uint src, uint len) {
	undo.fn = fn;
	undo.dst = src;
	undo.src = dst;
	undo.len = len;
	fn(&stacks[dst], &stacks[src], len);
}

static bool gameUndo(void) {
	if (!undo.fn) return false;
	undo.fn(&stacks[undo.dst], &stacks[undo.src], undo.len);
	undo.fn = NULL;
	return true;
}

static void gameDeal(void) {
	undo.fn = NULL;
	for (uint i = 0; i < StacksLen; ++i) {
		stackClear(&stacks[i]);
	}
	for (Card i = 1; i <= 52; ++i) {
		stackPush(&stacks[Stock], -i);
	}
	stackShuffle(&stacks[Stock]);
	for (uint i = Tableau1; i <= Tableau7; ++i) {
		stackMoveTo(&stacks[i], &stacks[Stock], i - Tableau1);
		stackFlipTo(&stacks[i], &stacks[Stock], 1);
	}
}

static void gameDraw(void) {
	stackMoveTo(&stacks[Waste1], &stacks[Waste3], stacks[Waste3].len);
	if (stacks[Stock].len) {
		if (game.draw > 1) {
			gameDo(stackFlipTo, Waste3, Stock, game.draw);
		} else {
			gameDo(stackFlipTo, Waste1, Stock, 1);
		}
	} else {
		gameDo(stackFlipTo, Stock, Waste1, stacks[Waste1].len);
	}
}

static bool gameFind(uint *stack, uint *index, Card card) {
	for (*stack = 0; *stack < StacksLen; ++*stack) {
		for (*index = 0; *index < stacks[*stack].len; ++*index) {
			if (stacks[*stack].cards[*index] == card) return true;
		}
	}
	return false;
}

static bool gameAvail(Card card) {
	uint stack, index;
	if (card < 0) return false;
	if (!gameFind(&stack, &index, card)) return false;

	bool top = (card == stackTop(&stacks[stack]));
	if (stack == Waste1) {
		return top && !stacks[Waste3].len;
	} else if (stack == Waste3) {
		return top;
	} else if (stack >= Foundation1 && stack <= Foundation4) {
		return top;
	} else if (stack >= Tableau1 && stack <= Tableau7) {
		return true;
	} else {
		return false;
	}
}

static bool gameReveal(Card card) {
	uint stack, index;
	if (!gameFind(&stack, &index, card)) return false;
	if (stack < Tableau1 || stack > Tableau7) return false;
	if (card != stackTop(&stacks[stack])) return false;
	if (card > 0) return false;
	gameDo(stackFlipTo, stack, stack, 1);
	return true;
}

static bool gameMove(uint dest, Card card) {
	uint source, index;
	if (!gameFind(&source, &index, card)) return false;
	if (source == dest) return false;

	uint count = stacks[source].len - index;
	Card destTop = stackTop(&stacks[dest]);

	if (dest >= Foundation1 && dest <= Foundation4) {
		if (count > 1) return false;
		if (!destTop && cardRank(card) != Cards_A) return false;
		if (destTop && cardSuit(card) != cardSuit(destTop)) return false;
		if (destTop && cardRank(card) != cardRank(destTop) + 1) return false;
		gameDo(stackMoveTo, dest, source, 1);
		return true;
	}

	if (dest >= Tableau1 && dest <= Tableau7) {
		if (!destTop && cardRank(card) != Cards_K) return false;
		if (destTop && cardColor(card) == cardColor(destTop)) return false;
		if (destTop && cardRank(card) != cardRank(destTop) - 1) return false;
		gameDo(stackMoveTo, dest, source, count);
		return true;
	}

	return false;
}

enum {
	StackMarginX = 11,
	StackMarginY = 6,

	StockX = StackMarginX,
	StockY = StackMarginY,

	WasteX = StockX + Cards_Width + StackMarginX,
	WasteY = StackMarginY,

	FoundationX = WasteX + 2 * (Cards_Width + StackMarginX),
	FoundationY = StackMarginY,

	TableauX = StackMarginX,
	TableauY = StockY + Cards_Height + StackMarginY,

	StackDeltaX = 2,
	StackDeltaY = 1,

	Waste3DeltaX = 14,
	Waste3DeltaY = StackDeltaY,

	TableauDeltaX = 0,
	TableauDeltaYBack = 3,
	TableauDeltaYFront = 15,

	WindowWidth = 7 * Cards_Width + 8 * StackMarginX,
	WindowHeight = 2 * (StackMarginY + Cards_Height)
		+ 6 * TableauDeltaYBack
		+ 12 * TableauDeltaYFront
		+ StackMarginY,
};

struct Item {
	SDL_Rect rect;
	uint texture;
	Card card;
};

struct List {
	uint len;
	struct Item items[52];
};

static void listPush(struct List *list, struct Item item) {
	assert(list->len < 52);
	list->items[list->len++] = item;
}

static struct {
	SDL_Rect stacks[StacksLen];
	struct List base;
	struct List main;
	struct List drag;
	struct Item dragItem;
	uint backTexture;
} layout;

static struct Item *layoutFind(const SDL_Point *point) {
	for (uint i = layout.main.len - 1; i < layout.main.len; --i) {
		if (SDL_PointInRect(point, &layout.main.items[i].rect)) {
			return &layout.main.items[i];
		}
	}
	return NULL;
}

static void layoutClear(void) {
	layout.base.len = 0;
	layout.main.len = 0;
	layout.drag.len = 0;
}

static void layoutCard(struct List **list, SDL_Rect *rect, Card card) {
	if (card == layout.dragItem.card) {
		*list = &layout.drag;
		*rect = layout.dragItem.rect;
	}
	uint texture = (card > 0 ? (uint)card : layout.backTexture);
	struct Item item = { *rect, texture, card };
	listPush(*list, item);
}

static void layoutStack(SDL_Rect *rect, const struct Stack *stack, uint depth) {
	struct List *list = &layout.main;
	for (uint i = 0; i < stack->len; ++i) {
		layoutCard(&list, rect, stack->cards[i]);
		if (i > 0 && i % (depth / 3) == 0) {
			rect->x += StackDeltaX;
			rect->y += StackDeltaY;
		}
	}
}

static void layoutStock(void) {
	SDL_Rect rect = { StockX, StockY, Cards_Width, Cards_Height };
	struct Item item = { rect, Cards_O, 0 };
	listPush(&layout.base, item);
	layout.stacks[Stock] = rect;
	layoutStack(&rect, &stacks[Stock], 24);
}

static void layoutWaste(void) {
	SDL_Rect rect = { WasteX, WasteY, Cards_Width, Cards_Height };
	layoutStack(&rect, &stacks[Waste1], 24);
	struct List *list = &layout.main;
	for (uint i = 0; i < stacks[Waste3].len; ++i) {
		layoutCard(&list, &rect, stacks[Waste3].cards[i]);
		rect.x += Waste3DeltaX;
		rect.y += Waste3DeltaY;
	}
}

static void layoutFoundations(void) {
	SDL_Rect base = { FoundationX, FoundationY, Cards_Width, Cards_Height };
	for (uint i = Foundation1; i <= Foundation4; ++i) {
		struct Item item = { base, Cards_Empty, 0 };
		listPush(&layout.base, item);
		layout.stacks[i] = base;
		SDL_Rect rect = base;
		layoutStack(&rect, &stacks[i], 13);
		base.x += Cards_Width + StackMarginX;
	}
}

static void layoutTableau(void) {
	SDL_Rect base = { TableauX, TableauY, Cards_Width, Cards_Height };
	for (uint i = Tableau1; i <= Tableau7; ++i) {
		SDL_Rect stack = { base.x, base.y, base.w, WindowHeight };
		layout.stacks[i] = stack;
		struct List *list = &layout.main;
		SDL_Rect rect = base;
		for (uint j = 0; j < stacks[i].len; ++j) {
			Card card = stacks[i].cards[j];
			layoutCard(&list, &rect, card);
			rect.x += TableauDeltaX;
			rect.y += (card > 0 ? TableauDeltaYFront : TableauDeltaYBack);
		}
		base.x += Cards_Width + StackMarginX;
	}
}

static bool keyDown(SDL_KeyboardEvent key) {
	switch (key.keysym.sym) {
		case SDLK_F2: gameDeal(); return true;
		case SDLK_BACKSPACE: return gameUndo();
		case SDLK_b: {
			layout.backTexture -= Cards_Back1;
			layout.backTexture += 1;
			layout.backTexture %= 12;
			layout.backTexture += Cards_Back1;
			return true;
		}
		case SDLK_d: {
			game.draw = (game.draw == 1 ? 3 : 1);
			gameDeal();
			return true;
		}
		default: return false;
	}
}

static bool mouseButtonDown(SDL_MouseButtonEvent button) {
	struct SDL_Point point = { button.x, button.y };
	if (SDL_PointInRect(&point, &layout.stacks[Stock])) {
		gameDraw();
		return true;
	}
	struct Item *item = layoutFind(&point);
	if (!item) return false;
	if (!gameAvail(item->card)) return gameReveal(item->card);
	if (button.clicks % 2 == 0) {
		for (uint dest = Foundation1; dest <= Foundation4; ++dest) {
			if (gameMove(dest, item->card)) return true;
		}
		return false;
	}
	layout.dragItem = *item;
	return true;
}

static bool mouseButtonUp(SDL_MouseButtonEvent button) {
	(void)button;
	if (!layout.dragItem.card) return false;
	for (uint dest = 0; dest < StacksLen; ++dest) {
		if (SDL_HasIntersection(&layout.dragItem.rect, &layout.stacks[dest])) {
			if (gameMove(dest, layout.dragItem.card)) break;
		}
	}
	layout.dragItem.card = 0;
	return true;
}

static bool mouseMotion(SDL_MouseMotionEvent motion) {
	if (!motion.state) return false;
	layout.dragItem.rect.x += motion.xrel;
	layout.dragItem.rect.y += motion.yrel;
	return true;
}

static SDL_Window *window;
static SDL_Renderer *render;
static SDL_Texture *textures[Cards_Count];

static void renderList(const struct List *list) {
	for (uint i = 0; i < list->len; ++i) {
		SDL_RenderCopy(
			render,
			textures[list->items[i].texture],
			NULL, &list->items[i].rect
		);
	}
}

static void err(const char *title) {
	int error = SDL_ShowSimpleMessageBox(
		SDL_MESSAGEBOX_ERROR, title, SDL_GetError(), window
	);
	if (error) fprintf(stderr, "%s\n", SDL_GetError());
	exit(EXIT_FAILURE);
}

int main(void) {
	if (SDL_Init(SDL_INIT_VIDEO) < 0) err("SDL_Init");
	atexit(SDL_Quit);

	char *prefPath = SDL_GetPrefPath("Causal Agency", "Cards");
	if (!prefPath) err("SDL_GetPrefPath");

	char *basePath = SDL_GetBasePath();
	if (!basePath) err("SDL_GetBasePath");

	char paths[4][1024];
	snprintf(paths[0], sizeof(paths[0]), "%sCARDS.DLL", prefPath);
	snprintf(paths[1], sizeof(paths[1]), "%sSOL.EXE", prefPath);
	snprintf(paths[2], sizeof(paths[2]), "%sCARDS.DLL", basePath);
	snprintf(paths[3], sizeof(paths[3]), "%sSOL.EXE", basePath);

	SDL_RWops *rw;
	for (uint i = 0; i < 4; ++i) {
		rw = SDL_RWFromFile(paths[i], "rb");
		if (rw) break;
	}
	if (!rw) {
		char buf[4096];
		snprintf(
			buf, sizeof(buf), "CARDS.DLL not found in:\n%s\n%s",
			prefPath, basePath
		);
		SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Cards", buf, NULL);
		return EXIT_FAILURE;
	}

	struct Cards *cards = Cards_Load(
		rw, Cards_ColorKey | Cards_AlphaCorners | Cards_BlackBorders
	);
	if (!cards) err("Cards_Load");
	SDL_RWclose(rw);

	int error = SDL_CreateWindowAndRenderer(
		WindowWidth, WindowHeight, SDL_WINDOW_ALLOW_HIGHDPI,
		&window, &render
	);
	if (error) err("SDL_CreateWindowAndRenderer");
	SDL_SetWindowTitle(window, "Solitaire");

	SDL_RenderSetIntegerScale(render, SDL_TRUE);
	SDL_RenderSetLogicalSize(render, WindowWidth, WindowHeight);

	for (uint i = 0; i < Cards_Count; ++i) {
		textures[i] = NULL;
		if (!cards->surfaces[i]) continue;
		textures[i] = SDL_CreateTextureFromSurface(render, cards->surfaces[i]);
		if (!textures[i]) err("SDL_CreateTextureFromSurface");
	}
	Cards_Free(cards);

	srand(time(NULL));
	layout.backTexture = Cards_Back1 + randUniform(12);
	gameDeal();

	for (;;) {
		layoutClear();
		layoutStock();
		layoutWaste();
		layoutFoundations();
		layoutTableau();

		SDL_SetRenderDrawColor(render, 0x00, 0xAA, 0x55, 0xFF);
		SDL_RenderClear(render);
		renderList(&layout.base);
		renderList(&layout.main);
		renderList(&layout.drag);
		SDL_RenderPresent(render);

		SDL_Event event;
		for (;;) {
			SDL_WaitEvent(&event);
			if (event.type == SDL_QUIT) {
				goto quit;
			} else if (event.type == SDL_KEYDOWN) {
				if (keyDown(event.key)) break;
			} else if (event.type == SDL_MOUSEBUTTONDOWN) {
				if (mouseButtonDown(event.button)) break;
			} else if (event.type == SDL_MOUSEBUTTONUP) {
				if (mouseButtonUp(event.button)) break;
			} else if (event.type == SDL_MOUSEMOTION) {
				if (mouseMotion(event.motion)) break;
			}
		}
	}

quit:
	SDL_Quit();
}