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+/*
+ * Copyright (c) 2019, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * * Neither the name of Redis nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * This file implements the LOLWUT command. The command should do something
+ * fun and interesting, and should be replaced by a new implementation at
+ * each new version of Redis.
+ *
+ * Thanks to Michele Hiki Falcone for the original image that inspired
+ * the image, part of his game, Plaguemon.
+ *
+ * Thanks to the Shhh computer art collective for the help in tuning the
+ * output to have a better artistic effect.
+ */
+
+#include "server.h"
+#include "lolwut.h"
+
+/* Render the canvas using the four gray levels of the standard color
+ * terminal: they match very well to the grayscale display of the gameboy. */
+static sds renderCanvas(lwCanvas *canvas) {
+ sds text = sdsempty();
+ for (int y = 0; y < canvas->height; y++) {
+ for (int x = 0; x < canvas->width; x++) {
+ int color = lwGetPixel(canvas,x,y);
+ char *ce; /* Color escape sequence. */
+
+ /* Note that we set both the foreground and background color.
+ * This way we are able to get a more consistent result among
+ * different terminals implementations. */
+ switch(color) {
+ case 0: ce = "0;30;40m"; break; /* Black */
+ case 1: ce = "0;90;100m"; break; /* Gray 1 */
+ case 2: ce = "0;37;47m"; break; /* Gray 2 */
+ case 3: ce = "0;97;107m"; break; /* White */
+ default: ce = "0;30;40m"; break; /* Just for safety. */
+ }
+ text = sdscatprintf(text,"\033[%s \033[0m",ce);
+ }
+ if (y != canvas->height-1) text = sdscatlen(text,"\n",1);
+ }
+ return text;
+}
+
+/* Draw a skyscraper on the canvas, according to the parameters in the
+ * 'skyscraper' structure. Window colors are random and are always one
+ * of the two grays. */
+struct skyscraper {
+ int xoff; /* X offset. */
+ int width; /* Pixels width. */
+ int height; /* Pixels height. */
+ int windows; /* Draw windows if true. */
+ int color; /* Color of the skyscraper. */
+};
+
+void generateSkyscraper(lwCanvas *canvas, struct skyscraper *si) {
+ int starty = canvas->height-1;
+ int endy = starty - si->height + 1;
+ for (int y = starty; y >= endy; y--) {
+ for (int x = si->xoff; x < si->xoff+si->width; x++) {
+ /* The roof is four pixels less wide. */
+ if (y == endy && (x <= si->xoff+1 || x >= si->xoff+si->width-2))
+ continue;
+ int color = si->color;
+ /* Alter the color if this is a place where we want to
+ * draw a window. We check that we are in the inner part of the
+ * skyscraper, so that windows are far from the borders. */
+ if (si->windows &&
+ x > si->xoff+1 &&
+ x < si->xoff+si->width-2 &&
+ y > endy+1 &&
+ y < starty-1)
+ {
+ /* Calculate the x,y position relative to the start of
+ * the window area. */
+ int relx = x - (si->xoff+1);
+ int rely = y - (endy+1);
+
+ /* Note that we want the windows to be two pixels wide
+ * but just one pixel tall, because terminal "pixels"
+ * (characters) are not square. */
+ if (relx/2 % 2 && rely % 2) {
+ do {
+ color = 1 + rand() % 2;
+ } while (color == si->color);
+ /* Except we want adjacent pixels creating the same
+ * window to be the same color. */
+ if (relx % 2) color = lwGetPixel(canvas,x-1,y);
+ }
+ }
+ lwDrawPixel(canvas,x,y,color);
+ }
+ }
+}
+
+/* Generate a skyline inspired by the parallax backgrounds of 8 bit games. */
+void generateSkyline(lwCanvas *canvas) {
+ struct skyscraper si;
+
+ /* First draw the background skyscraper without windows, using the
+ * two different grays. We use two passes to make sure that the lighter
+ * ones are always in the background. */
+ for (int color = 2; color >= 1; color--) {
+ si.color = color;
+ for (int offset = -10; offset < canvas->width;) {
+ offset += rand() % 8;
+ si.xoff = offset;
+ si.width = 10 + rand()%9;
+ if (color == 2)
+ si.height = canvas->height/2 + rand()%canvas->height/2;
+ else
+ si.height = canvas->height/2 + rand()%canvas->height/3;
+ si.windows = 0;
+ generateSkyscraper(canvas, &si);
+ if (color == 2)
+ offset += si.width/2;
+ else
+ offset += si.width+1;
+ }
+ }
+
+ /* Now draw the foreground skyscraper with the windows. */
+ si.color = 0;
+ for (int offset = -10; offset < canvas->width;) {
+ offset += rand() % 8;
+ si.xoff = offset;
+ si.width = 5 + rand()%14;
+ if (si.width % 4) si.width += (si.width % 3);
+ si.height = canvas->height/3 + rand()%canvas->height/2;
+ si.windows = 1;
+ generateSkyscraper(canvas, &si);
+ offset += si.width+5;
+ }
+}
+
+/* The LOLWUT 6 command:
+ *
+ * LOLWUT [columns] [rows]
+ *
+ * By default the command uses 80 columns, 40 squares per row
+ * per column.
+ */
+void lolwut6Command(client *c) {
+ long cols = 80;
+ long rows = 20;
+
+ /* Parse the optional arguments if any. */
+ if (c->argc > 1 &&
+ getLongFromObjectOrReply(c,c->argv[1],&cols,NULL) != C_OK)
+ return;
+
+ if (c->argc > 2 &&
+ getLongFromObjectOrReply(c,c->argv[2],&rows,NULL) != C_OK)
+ return;
+
+ /* Limits. We want LOLWUT to be always reasonably fast and cheap to execute
+ * so we have maximum number of columns, rows, and output resolution. */
+ if (cols < 1) cols = 1;
+ if (cols > 1000) cols = 1000;
+ if (rows < 1) rows = 1;
+ if (rows > 1000) rows = 1000;
+
+ /* Generate the city skyline and reply. */
+ lwCanvas *canvas = lwCreateCanvas(cols,rows,3);
+ generateSkyline(canvas);
+ sds rendered = renderCanvas(canvas);
+ rendered = sdscat(rendered,
+ "\nDedicated to the 8 bit game developers of past and present.\n"
+ "Original 8 bit image from Plaguemon by hikikomori. Redis ver. ");
+ rendered = sdscat(rendered,REDIS_VERSION);
+ rendered = sdscatlen(rendered,"\n",1);
+ addReplyVerbatim(c,rendered,sdslen(rendered),"txt");
+ sdsfree(rendered);
+ lwFreeCanvas(canvas);
+}