1 files changed, 103 insertions, 0 deletions
diff --git a/src/server/repl.ts b/src/server/repl.ts
new file mode 100644
index 000000000..ec525582b
--- /dev/null
+++ b/src/server/repl.ts
@@ -0,0 +1,103 @@
+import { createInterface, Interface } from "readline";
+import { red } from "colors";
+
+export interface Configuration {
+    identifier: string;
+    onInvalid?: (culprit?: string) => string | string;
+    isCaseSensitive?: boolean;
+}
+
+type Action = (parsedArgs: IterableIterator<string>) => any | Promise<any>;
+export interface Registration {
+    argPatterns: RegExp[];
+    action: Action;
+}
+
+export default class Repl {
+    private identifier: string;
+    private onInvalid: ((culprit?: string) => string) | string;
+    private isCaseSensitive: boolean;
+    private commandMap = new Map<string, Registration[]>();
+    public interface: Interface;
+    private busy = false;
+    private keys: string | undefined;
+
+    constructor({ identifier: prompt, onInvalid, isCaseSensitive }: Configuration) {
+        this.identifier = prompt;
+        this.onInvalid = onInvalid || this.usage;
+        this.isCaseSensitive = isCaseSensitive ?? true;
+        this.interface = createInterface(process.stdin, process.stdout).on('line', this.considerInput);
+    }
+
+    private usage = () => {
+        const resolved = this.keys;
+        if (resolved) {
+            return resolved;
+        }
+        const members: string[] = [];
+        const keys = this.commandMap.keys();
+        let next: IteratorResult<string>;
+        while (!(next = keys.next()).done) {
+            members.push(next.value);
+        }
+        return `${this.identifier} commands: { ${members.sort().join(", ")} }`;
+    }
+
+    public registerCommand = (basename: string, argPatterns: (RegExp | string)[], action: Action) => {
+        const existing = this.commandMap.get(basename);
+        const converted = argPatterns.map(input => input instanceof RegExp ? input : new RegExp(input));
+        const registration = { argPatterns: converted, action };
+        if (existing) {
+            existing.push(registration);
+        } else {
+            this.commandMap.set(basename, [registration]);
+        }
+    }
+
+    private invalid = (culprit?: string) => {
+        console.log(red(typeof this.onInvalid === "string" ? this.onInvalid : this.onInvalid(culprit)));
+        this.busy = false;
+    }
+
+    private considerInput = async (line: string) => {
+        if (this.busy) {
+            console.log(red("Busy"));
+            return;
+        }
+        this.busy = true;
+        line = line.trim();
+        if (this.isCaseSensitive) {
+            line = line.toLowerCase();
+        }
+        const [command, ...args] = line.split(/\s+/g);
+        if (!command) {
+            return this.invalid();
+        }
+        const registered = this.commandMap.get(command);
+        if (registered) {
+            const { length } = args;
+            const candidates = registered.filter(({ argPatterns: { length: count } }) => count === length);
+            for (const { argPatterns, action } of candidates) {
+                const parsed: string[] = [];
+                let matched = false;
+                if (length) {
+                    for (let i = 0; i < length; i++) {
+                        let matches: RegExpExecArray | null;
+                        if ((matches = argPatterns[i].exec(args[i])) === null) {
+                            break;
+                        }
+                        parsed.push(matches[0]);
+                    }
+                    matched = true;
+                }
+                if (!length || matched) {
+                    await action(parsed[Symbol.iterator]());
+                    this.busy = false;
+                    return;
+                }
+            }
+        }
+        this.invalid(command);
+    }
+
+}
+\ No newline at end of file