From dd498e15cdddb187b12c37c4dad4f09073cd9747 Mon Sep 17 00:00:00 2001
From: Manuel Friedli <manuel@fritteli.ch>
Date: Sat, 8 Apr 2023 23:46:27 +0200
Subject: [PATCH] Add interactiveness to HTML outputs.

---
 .../generator/renderer/html/HTMLRenderer.java | 112 +++++++++++++++++-
 1 file changed, 107 insertions(+), 5 deletions(-)

diff --git a/src/main/java/ch/fritteli/labyrinth/generator/renderer/html/HTMLRenderer.java b/src/main/java/ch/fritteli/labyrinth/generator/renderer/html/HTMLRenderer.java
index fc03f38..c5b3aa6 100644
--- a/src/main/java/ch/fritteli/labyrinth/generator/renderer/html/HTMLRenderer.java
+++ b/src/main/java/ch/fritteli/labyrinth/generator/renderer/html/HTMLRenderer.java
@@ -5,7 +5,109 @@ import ch.fritteli.labyrinth.generator.renderer.Renderer;
 import lombok.NonNull;
 
 public class HTMLRenderer implements Renderer<String> {
-    private static final String POSTAMBLE = "</body></html>";
+
+    private static final String POSTAMBLE = "<script>"
+            + "let userPath = [];"
+            + "const DIR_UNDEF = -1;"
+            + "const DIR_SAME = 0;"
+            + "const DIR_UP = 1;"
+            + "const DIR_RIGHT = 2;"
+            + "const DIR_DOWN = 3;"
+            + "const DIR_LEFT = 4;"
+            + "function getCoords(cell) {"
+            + "    return {"
+            + "        x: cell.cellIndex,"
+            + "        y: cell.parentElement.rowIndex"
+            + "    };"
+            + "}"
+            + "function distance(prev, next) {"
+            + "    return Math.abs(prev.x - next.x) + Math.abs(prev.y - next.y);"
+            + "}"
+            + "function direction(prev, next) {"
+            + "    const dist = distance(prev, next);"
+            + "    if (dist === 0) {"
+            + "        return DIR_SAME;"
+            + "    }"
+            + "    if (dist !== 1) {"
+            + "        return DIR_UNDEF;"
+            + "    }"
+            + "    if (next.x === prev.x) {"
+            + "        if (next.y === prev.y + 1) {"
+            + "            return DIR_DOWN;"
+            + "        }"
+            + "        return DIR_UP;"
+            + "    }"
+            + "    if (next.x === prev.x + 1) {"
+            + "        return DIR_RIGHT;"
+            + "    }"
+            + "    return DIR_LEFT;"
+            + "}"
+            + "(function () {"
+            + "    const labyrinthTable = document.getElementById(\"labyrinth\");"
+            + "    const labyrinthCells = labyrinthTable.getElementsByTagName(\"td\");"
+            + "    const start = {x: 0, y: 0};"
+            + "    const end = {"
+            + "        x: labyrinthTable.getElementsByTagName(\"tr\")[0].getElementsByTagName(\"td\").length - 1,"
+            + "        y: labyrinthTable.getElementsByTagName(\"tr\").length - 1"
+            + "    };"
+            + "    for (let i = 0; i < labyrinthCells.length; i++) {"
+            + "        let cell = labyrinthCells.item(i);"
+            + "        cell.onclick = (event) => {"
+            + "            let target = event.target;"
+            + "            const coords = getCoords(target);"
+            + "            if (coords.x === end.x && coords.y === end.y) {"
+            + "                alert(\"HOORAY! You did it! Congratulations!\")"
+            + "            }"
+            + "            if (userPath.length === 0) {"
+            + "                if (coords.x === start.x && coords.y === start.y) {"
+            + "                    userPath.push(coords);"
+            + "                    target.classList.toggle(\"user\");"
+            + "                }"
+            + "            } else {"
+            + "                const dir = direction(userPath[userPath.length - 1], coords);"
+            + "                switch (dir) {"
+            + "                    case DIR_UNDEF:"
+            + "                        return;"
+            + "                    case DIR_SAME:"
+            + "                        userPath.pop();"
+            + "                        target.classList.toggle(\"user\");"
+            + "                        return;"
+            + "                    default:"
+            + "                        if (userPath.find(value => value.x === coords.x && value.y === coords.y)) {"
+            + "                            return;"
+            + "                        } else {"
+            + "                            switch (dir) {"
+            + "                                case DIR_UP:"
+            + "                                    if (target.classList.contains(\"bottom\")) {"
+            + "                                        return;"
+            + "                                    }"
+            + "                                    break;"
+            + "                                case DIR_RIGHT:"
+            + "                                    if (target.classList.contains(\"left\")) {"
+            + "                                        return;"
+            + "                                    }"
+            + "                                    break;"
+            + "                                case DIR_DOWN:"
+            + "                                    if (target.classList.contains(\"top\")) {"
+            + "                                        return;"
+            + "                                    }"
+            + "                                    break;"
+            + "                                case DIR_LEFT:"
+            + "                                    if (target.classList.contains(\"right\")) {"
+            + "                                        return;"
+            + "                                    }"
+            + "                                    break;"
+            + "                            }"
+            + "                            userPath.push(coords);"
+            + "                            target.classList.toggle(\"user\");"
+            + "                            return;"
+            + "                        }"
+            + "                }"
+            + "            }"
+            + "        };"
+            + "    }"
+            + "})();"
+            + "</script></body></html>";
 
     private HTMLRenderer() {
     }
@@ -23,7 +125,7 @@ public class HTMLRenderer implements Renderer<String> {
         }
         final Generator generator = new Generator(labyrinth);
         final StringBuilder sb = new StringBuilder(this.getPreamble(labyrinth));
-        sb.append("<table>");
+        sb.append("<table id=\"labyrinth\">");
         while (generator.hasNext()) {
             sb.append(generator.next());
         }
@@ -39,11 +141,12 @@ public class HTMLRenderer implements Renderer<String> {
                 "<meta charset=\"utf-8\">" +
                 "<style>" +
                 "table{border-collapse:collapse;}" +
-                "td{border:0 solid black;height:1em;width:1em;}" +
+                "td{border:0 solid black;height:1em;width:1em;cursor:pointer;}" +
                 "td.top{border-top-width:1px;}" +
                 "td.right{border-right-width:1px;}" +
                 "td.bottom{border-bottom-width:1px;}" +
                 "td.left{border-left-width:1px;}" +
+                "td.user{background:hotpink;}" +
                 "</style>" +
                 "<script>" +
                 "let solution = false;" +
@@ -59,7 +162,6 @@ public class HTMLRenderer implements Renderer<String> {
                 "</script>" +
                 "</head>" +
                 "<body>" +
-                "<input type=\"checkbox\" onclick=\"toggleSolution()\">show solution</input>";
+                "<input id=\"solutionbox\" type=\"checkbox\" onclick=\"toggleSolution()\"/><label for=\"solutionbox\">show solution</label>";
     }
-
 }