From 2ef8f81d4e0cbdb4ce9c8e7eabc9c8b69459844d Mon Sep 17 00:00:00 2001
From: Pavel 'LEdoian' Turinsky <ledoian@matfyz.cz>
Date: Sat, 21 Oct 2023 00:22:06 +0200
Subject: [PATCH] [WIP] C template

---
 C/lib.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 C/lib.h | 39 +++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+)
 create mode 100644 C/lib.c
 create mode 100644 C/lib.h

diff --git a/C/lib.c b/C/lib.c
new file mode 100644
index 0000000..655334b
--- /dev/null
+++ b/C/lib.c
@@ -0,0 +1,76 @@
+#include "lib.h"
+
+static int actual_tile_size, actual_grid_height, actual_grid_width;
+static bool was_init = false;
+
+static SDL_Window * window;
+static SDL_Surface * win_surface;
+static SDL_Surface * grid_sfc;
+
+void init(void) {
+	if (was_init) {
+		fprintf(stderr, "Cannot re-initialize.\n");
+		abort(); // Life is tough, you do not deserve to handle this.
+		         // Actually, crashing is the better behaviour in this case…
+	}
+	was_init = true;
+	actual_tile_size = TILE_SIZE;
+	actual_grid_height = GRID_HEIGHT;
+	actual_grid_width = GRID_WIDTH;
+
+	if (SDL_Init( SDL_INIT_VIDEO ) < 0) {
+		fprintf(stderr, "SDL_Init error: %s\n", SDL_GetError());
+		abort();
+	}
+
+	grid = malloc(actual_grid_width * sizeof(color_t *));
+	for (int i = 0; i < actual_grid_width; i++) {
+		grid[i] = malloc(actual_grid_height * sizeof(color_t));
+		for (int j = 0; j < actual_grid_height; j++) grid[i][j] = (color_t) {0,0,0};
+	}
+
+	// TODO: Maybe add margins?
+	int winh = actual_tile_size * actual_grid_height;
+	int winw = actual_tile_size * actual_grid_width;
+	window = SDL_CreateWindow("Snake?", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, winw, winh, SDL_WINDOW_SHOWN);
+	if (window == NULL) {
+		fprintf(stderr, "Window broken: %s\n", SDL_GetError());
+		abort();
+	}
+	win_surface = SDL_GetWindowSurface(window);
+
+	grid_sfc = SDL_CreateRGBSurface(0, winw, winh, 24, 0,0,0,0);
+	
+	// Ensure something is shown.
+	redraw();
+}
+
+void redraw(void) {
+	for (int x = 0; x < actual_grid_width; x++) {
+		for (int y = 0; y < actual_grid_height; y++) {
+			color_t c = grid[x][y];
+			uint32_t color = (c.r << 24) + (c.g << 16) + (c.b << 8) + 0xFF /* alpha */;
+			SDL_Rect rect = {.x = x * actual_tile_size, .y = y * actual_tile_size,
+				.h = actual_tile_size, .w = actual_tile_size};
+			SDL_FillRect(grid_sfc, &rect, color);
+		}
+	}
+}
+
+char ** getkeys(int count) {
+
+}
+
+/* The simple stuff */
+void grid_set(int x, int y, color_t c) {
+	// FIXME: bounds checks!
+	grid[x][y] = c;
+}
+
+color_t grid_get(int x, int y) {
+	return grid[x][y];
+}
+
+void wait(int msec) {
+	SDL_Delay(msec);
+}
diff --git a/C/lib.h b/C/lib.h
new file mode 100644
index 0000000..8053efd
--- /dev/null
+++ b/C/lib.h
@@ -0,0 +1,39 @@
+#pragma once
+#include <SDL2/SDL.h>
+
+// Convenience: also get many stdlibs, so that we do not need to care in the program
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef unsigned char byte;
+
+typedef struct color {
+	byte r;
+	byte g;
+	byte b;
+} color_t;
+
+/* These are mutable, so that it is easy to change them from the code, before runing init() */
+int TILE_SIZE = 5;
+int GRID_HEIGHT = 20;
+int GRID_WIDTH = 20;
+
+color_t ** grid;
+
+/* We wrap SDL as a whole, so this is our API. */
+void init(void);
+void redraw(void);
+void wait(int msec); // Not a regular usleep, since we want SDL to still get inputs
+char **getkeys(int count); // Get up to `count` keys pressed since last call. These are strings like 'a', 'shift', 'up', &c.
+                           // We only report keydowns, and we report them in order they were pressed.
+/* low-level Grid API */
+void grid_set(int x, int y, color_t color);
+color_t grid_get(int x, int y);
+// Of course, this is fourth quadrant, i.e. the origin is top left corner.
+
+/* I thought of providing a growing array here, but my implementation is too
+ * ugly (e.g. too many void pointers).  Use reallocarray(3) instead, or just a
+ * regular array big enough. */