/* 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 <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include "asset.h"
#include "cards.h"
#include "layout.h"
#include "stack.h"

enum {
	Foundation1,
	Foundation2,
	Foundation3,
	Foundation4,
	Cell1,
	Cell2,
	Cell3,
	Cell4,
	Tableau1,
	Tableau2,
	Tableau3,
	Tableau4,
	Tableau5,
	Tableau6,
	Tableau7,
	Tableau8,
	StacksLen,
};

static struct Stack stacks[StacksLen];

static struct {
	bool avail;
	uint dst;
	uint src;
} undo;

static uint kingFace = Cards_KingRight;

static void gameDeal(void) {
	for (uint i = 0; i < StacksLen; ++i) {
		stackClear(&stacks[i]);
	}
	struct Stack deck = {0};
	for (Card i = 1; i <= 52; ++i) {
		stackPush(&deck, i);
	}
	stackShuffle(&deck);
	for (uint i = Tableau1; i <= Tableau8; ++i) {
		stackMoveTo(&stacks[i], &deck, (i < Tableau5 ? 7 : 6));
	}
	undo.avail = false;
	kingFace = Cards_KingRight;
}

static bool gameWin(void) {
	for (uint i = Foundation1; i <= Foundation4; ++i) {
		if (stacks[i].len != 13) return false;
	}
	return true;
}

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

static bool gameAvail(Card card) {
	uint stack;
	assert(gameFind(&stack, card));
	if (stack <= Foundation4) return false;
	return card == stackTop(&stacks[stack]);
}

static bool gameMove(uint dst, Card card) {
	uint src;
	assert(gameFind(&src, card));
	Card top = stackTop(&stacks[dst]);

	if (src == dst) return false;
	if (dst >= Cell1 && dst <= Cell4) {
		if (stacks[dst].len) return false;
		kingFace = Cards_KingLeft;
	}
	if (dst >= Foundation1 && dst <= Foundation4) {
		if (!top && cardRank(card) != Cards_A) return false;
		if (top && cardSuit(card) != cardSuit(top)) return false;
		if (top && cardRank(card) != cardRank(top) + 1) return false;
		kingFace = Cards_KingRight;
	}
	if (dst >= Tableau1 && dst <= Tableau8) {
		if (top && cardColor(card) == cardColor(top)) return false;
		if (top && cardRank(card) != cardRank(top) - 1) return false;
	}

	undo.dst = src;
	undo.src = dst;
	undo.avail = true;
	stackPush(&stacks[dst], stackPop(&stacks[src]));
	return true;
}

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

static bool gameAuto(void) {
	Card min[2] = { Cards_K, Cards_K };
	for (uint i = Cell1; i <= Tableau8; ++i) {
		for (uint j = 0; j < stacks[i].len; ++j) {
			Card card = stacks[i].cards[j];
			if (cardRank(card) < min[cardColor(card)]) {
				min[cardColor(card)] = cardRank(card);
			}
		}
	}
	for (uint i = Cell1; i <= Tableau8; ++i) {
		Card card = stackTop(&stacks[i]);
		if (!card) continue;
		if (cardRank(card) > Cards_2) {
			if (min[!cardColor(card)] < cardRank(card)) continue;
		}
		for (uint dst = Foundation1; dst <= Foundation4; ++dst) {
			if (gameMove(dst, card)) return true;
		}
	}
	return false;
}

enum {
	CardWidth = Cards_CardWidth,
	CardHeight = Cards_CardHeight,

	CellX = 0,
	CellY = 0,

	KingMarginX = 13,
	KingX = CellX + 4 * CardWidth + KingMarginX,
	KingY = 18,
	KingPadX = 3,
	KingPadY = 3,
	KingWidth = Cards_KingWidth + 2 * KingPadX,
	KingHeight = Cards_KingHeight + 2 * KingPadY,

	FoundationX = KingX + KingWidth + KingMarginX,
	FoundationY = CellY,

	StackMarginX = 7,
	StackMarginY = 10,

	TableauX = StackMarginX,
	TableauY = CellY + CardHeight + StackMarginY,
	FanDownDeltaY = 17,

	KingWinMarginX = 10,
	KingWinMarginY = 10,
	KingWinX = KingWinMarginX,
	KingWinY = CellY + CardHeight + KingWinMarginY,
	KingWinWidth = 320,
	KingWinHeight = 320,

	WindowWidth = 8 * CardWidth + 9 * StackMarginX + 1,
	WindowHeight = KingWinY + KingWinHeight + KingWinMarginY,
};

static const struct Style FanDown = { 1, 0, 0, 0, FanDownDeltaY };

static struct SDL_Rect stackRects[StacksLen];
static struct Layout layout;
static struct List reveal;

static void updateLayout(void) {
	layoutClear(&layout);

	SDL_Rect cell = { CellX, CellY, CardWidth, CardHeight };
	for (uint i = Cell1; i <= Cell4; ++i) {
		stackRects[i] = cell;
		layoutStack(&layout, &cell, &stacks[i], &Flat);
		cell.x += CardWidth;
	}

	SDL_Rect found = { FoundationX, FoundationY, CardWidth, CardHeight };
	for (uint i = Foundation1; i <= Foundation4; ++i) {
		stackRects[i] = found;
		layoutStack(&layout, &found, &stacks[i], &Flat);
		found.x += CardWidth;
	}

	SDL_Rect table = { TableauX, TableauY, CardWidth, CardHeight };
	for (uint i = Tableau1; i <= Tableau8; ++i) {
		stackRects[i] = table;
		stackRects[i].h = WindowHeight;
		SDL_Rect rect = table;
		layoutStack(&layout, &rect, &stacks[i], &FanDown);
		table.x += CardWidth + StackMarginX;
	}
}

static void revealRank(Card rank) {
	for (uint i = 0; i < layout.main.len; ++i) {
		struct Item item = layout.main.items[i];
		if (cardRank(item.card) != rank) continue;
		listPush(&reveal, &item.rect, item.card);
	}
}

static bool keyDown(SDL_KeyboardEvent key) {
	switch (key.keysym.sym) {
		case SDLK_F2: gameDeal(); return true;
		case SDLK_BACKSPACE: return gameUndo();
	}
	if (key.repeat) return false;
	switch (key.keysym.sym) {
		break; case SDLK_a: revealRank(Cards_A);
		break; case SDLK_2: revealRank(Cards_2);
		break; case SDLK_3: revealRank(Cards_3);
		break; case SDLK_4: revealRank(Cards_4);
		break; case SDLK_5: revealRank(Cards_5);
		break; case SDLK_6: revealRank(Cards_6);
		break; case SDLK_7: revealRank(Cards_7);
		break; case SDLK_8: revealRank(Cards_8);
		break; case SDLK_9: revealRank(Cards_9);
		break; case SDLK_1: revealRank(Cards_10);
		break; case SDLK_0: revealRank(Cards_10);
		break; case SDLK_j: revealRank(Cards_J);
		break; case SDLK_q: revealRank(Cards_Q);
		break; case SDLK_k: revealRank(Cards_K);
		break; default: return false;
	}
	return true;
}

static bool keyUp(SDL_KeyboardEvent key) {
	(void)key;
	if (!reveal.len) return false;
	listClear(&reveal);
	return true;
}

static bool mouseButtonDown(SDL_MouseButtonEvent button) {
	if (button.button != SDL_BUTTON_RIGHT) return false;
	struct SDL_Point point = { button.x, button.y };
	struct Item *item = listFind(&layout.main, &point);
	if (!item) return false;
	listPush(&reveal, &item->rect, item->card);
	return true;
}

static bool mouseButtonUp(SDL_MouseButtonEvent button) {
	struct SDL_Point point = { button.x, button.y };

	if (button.button == SDL_BUTTON_RIGHT) {
		if (!reveal.len) return false;
		listClear(&reveal);
		return true;
	}

	if (button.clicks % 2 == 0) {
		Card card = layout.dragItem.card;
		if (!card) {
			struct Item *item = listFind(&layout.main, &point);
			if (!item) return false;
			card = item->card;
		}
		if (!gameAvail(card)) return false;
		for (uint dst = Cell1; dst <= Cell4; ++dst) {
			if (gameMove(dst, card)) break;
		}
		layout.dragItem.card = 0;
		return true;
	}

	if (layout.dragItem.card) {
		for (uint dst = 0; dst < StacksLen; ++dst) {
			if (SDL_PointInRect(&point, &stackRects[dst])) {
				if (gameMove(dst, layout.dragItem.card)) break;
			}
		}
		layout.dragItem.card = 0;
		return true;
	}

	struct Item *item = listFind(&layout.main, &point);
	if (!item) return false;
	if (!gameAvail(item->card)) return false;
	layout.dragItem = *item;
	return true;
}

static SDL_Renderer *render;

static void renderOutline(SDL_Rect rect, bool out) {
	int right = rect.x + rect.w - 1;
	int bottom = rect.y + rect.h - 1;
	SDL_Point topLeft[3] = {
		{ rect.x, bottom - 1 },
		{ rect.x, rect.y },
		{ right - 1, rect.y },
	};
	SDL_Point bottomRight[3] = {
		{ rect.x + 1, bottom },
		{ right, bottom },
		{ right, rect.y + 1 },
	};
	SDL_SetRenderDrawColor(render, 0x00, 0x00, 0x00, 0xFF);
	SDL_RenderDrawLines(render, out ? bottomRight : topLeft, 3);
	SDL_SetRenderDrawColor(render, 0x00, 0xFF, 0x00, 0xFF);
	SDL_RenderDrawLines(render, out ? topLeft : bottomRight, 3);
}

static void renderOutlines(void) {
	for (uint i = Foundation1; i <= Cell4; ++i) {
		renderOutline(stackRects[i], false);
	}
}

static void renderKing(SDL_Texture *textures[]) {
	SDL_Rect box = { KingX, KingY, KingWidth, KingHeight };
	renderOutline(box, true);
	if (gameWin()) {
		SDL_Rect king = { KingWinX, KingWinY, KingWinWidth, KingWinHeight };
		SDL_RenderCopy(render, textures[Cards_KingWin], NULL, &king);
	} else {
		SDL_Rect king = {
			KingX + KingPadX, KingY + KingPadY,
			Cards_KingWidth, Cards_KingHeight,
		};
		SDL_RenderCopy(render, textures[kingFace], NULL, &king);
	}
}

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

static void err(const char *title) {
	int error = SDL_ShowSimpleMessageBox(
		SDL_MESSAGEBOX_ERROR, title, SDL_GetError(), NULL
	);
	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);

	struct Paths paths;
	if (assetPaths(&paths) < 0) err("SDL_GetPrefPath");

	bool kings = false;
	struct {
		SDL_Surface *cards[Cards_Empty];
		SDL_Surface *kings[Cards_FreeCellCount];
	} surfaces;

	SDL_RWops *rw = assetOpenCards(&paths);
	if (!rw) return EXIT_FAILURE;
	int error = Cards_LoadCards(
		surfaces.cards, Cards_Empty,
		rw, Cards_AlphaCorners | Cards_BlackBorders
	);
	if (error) err("Cards_LoadCards");
	SDL_RWclose(rw);

	rw = assetOpenFreeCell(&paths);
	if (rw) {
		kings = true;
		int error = Cards_LoadFreeCell(
			surfaces.kings, Cards_FreeCellCount,
			rw, Cards_ColorKey
		);
		if (error) err("Cards_LoadFreeCell");
		SDL_RWclose(rw);
	}

	SDL_Window *window;
	error = SDL_CreateWindowAndRenderer(
		WindowWidth, WindowHeight, SDL_WINDOW_ALLOW_HIGHDPI,
		&window, &render
	);
	if (error) err("SDL_CreateWindowAndRenderer");
	SDL_SetWindowTitle(window, "FreeCell");

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

	SDL_Texture *textures[Cards_Empty] = {0};
	SDL_Texture *inverted[Cards_Empty] = {0};
	SDL_Texture *kingTextures[Cards_FreeCellCount] = {0};

	for (uint i = 0; i < Cards_Empty; ++i) {
		if (!surfaces.cards[i]) continue;

		textures[i] = SDL_CreateTextureFromSurface(render, surfaces.cards[i]);
		if (!textures[i]) err("SDL_CreateTextureFromSurface");

		error = Cards_InvertSurface(surfaces.cards[i]);
		if (error) err("Cards_InvertSurface");

		inverted[i] = SDL_CreateTextureFromSurface(render, surfaces.cards[i]);
		if (!inverted[i]) err("SDL_CreateTextureFromSurface");

		SDL_FreeSurface(surfaces.cards[i]);
	}

	if (kings) {
		for (uint i = 0; i < Cards_FreeCellCount; ++i) {
			if (!surfaces.kings[i]) continue;
			kingTextures[i] =
				SDL_CreateTextureFromSurface(render, surfaces.kings[i]);
			if (!kingTextures[i]) err("SDL_CreateTextureFromSurface");
			SDL_FreeSurface(surfaces.kings[i]);
		}
	}

	srand(time(NULL));
	gameDeal();

	for (;;) {
		updateLayout();

		SDL_SetRenderDrawColor(render, 0x00, 0xAA, 0x55, 0xFF);
		SDL_RenderClear(render);
		renderOutlines();
		if (kings) renderKing(kingTextures);
		renderList(textures, &layout.main);
		renderList(inverted, &layout.drag);
		renderList(textures, &reveal);
		SDL_RenderPresent(render);

		// TODO: Add more than a frame delay between automatic moves?
		if (gameAuto()) continue;

		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_KEYUP) {
				if (keyUp(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;
			}
		}
	}

quit:
	SDL_Quit();
}