improve exception handing and add more commands

src/commands/commands.js

@@ -4,5 +4,65 @@ export default {
     },
     wine: function(ctx) {
         return `${ctx.streamInput + " " ?? ""}:wine_glass:`;
+    },
+    slot: function(ctx) {
+        const template = ctx.argv.join(" ");
+        const slot = ctx.streamInput ?? "";
+        return template.replace("%%", slot);
+    },
+    times: function(ctx) {
+        const times = parseInt(ctx.argv[0]);
+        const text = ctx.streamInput;
+        if (!times) {
+            return "times: expected first argument to be the number of times to repeat text";
+        }
+        if (!text) {
+            return "times: expected stream input";
+        }
+
+        let out = "";
+        for (let i = 0; i < times; i++) {
+            out += text;
+        }
+        return out;
+    },
+    djson: function(ctx) {
+        if (ctx.argc > 24) {
+            return "djson: arbitrary nesting limit of 24 reached"
+        }
+
+        if (ctx.argc < 1) {
+            return "djson: expected one or more arguments";
+        }
+
+        if (!ctx.streamInput) {
+            return "djson: expected stream input";
+        }
+
+        let json;
+        try {
+            json = JSON.parse(ctx.streamInput);
+        } catch (e) {
+            return "djson: failed to parse json, is it malformed?";
+        }
+        const fields = ctx.argv;
+
+        let val = json;
+        for (let i = 0; i < fields.length; i++) {
+            const field = fields[i];
+
+            if (field.includes("__")) {
+                return "djson: security violation - field names that contain __ are disallowed";
+            }
+
+            if (typeof val !== "object") {
+                return "null";
+            }
+            val = val[field];
+        }
+
+        val ??= "null";
+
+        return typeof val === "string" ? val : JSON.stringify(val);
     }
 }

src/commands/interperter.js

@@ -164,13 +164,20 @@ function interpretInstructions(instructions, displayFunc) {
                 if (inst.inStream) {
                     streamInput = streams.get(inst.inStream);
                 }
-                let streamOutput = commandFunc({
-                    argv: inst.args,
-                    argc: inst.args.length,
-                    streamInput
-                });
-                if (inst.outStream) {
-                    streams.set(inst.outStream, streamOutput);
+                try {
+                    let streamOutput = commandFunc({
+                        argv: inst.args,
+                        argc: inst.args.length,
+                        streamInput
+                    });
+                    if (inst.outStream) {
+                        streams.set(inst.outStream, streamOutput);
+                    }
+                } catch(e) {
+                    console.error("unhandled exception while running command", e);
+                    if (inst.outStream) {
+                        streams.set(inst.outStream, "error: unhandled internal exception");
+                    }
                 }
                 break;
             }