refactor: better proxy clipboard autofill

src/lib/proxy-string.ts

@@ -0,0 +1,127 @@
+/**
+ * Reading a proxy out of a pasted line.
+ *
+ * The parser itself is Rust's `parse_txt_proxies`
+ * (`src-tauri/src/proxy_manager.rs`); both the import dialog and the add/edit
+ * form hand their clipboard text to it rather than re-implementing the format
+ * zoo. What is left for the frontend is the part the backend deliberately
+ * refuses to decide: `a:b:c:d` is either `host:port:username:password` or
+ * `username:password:host:port`, and when both middle fields parse as a port
+ * only the user knows which. The backend reports that as `ambiguous`; the
+ * functions below turn the user's answer back into a proxy.
+ *
+ * Kept free of runtime imports so `proxy-string.test.mjs` can load it directly.
+ */
+
+import type { ParsedProxyLine, ProxyParseResult } from "@/types";
+
+/** URL schemes the Rust parser accepts, mapped onto the stored proxy type. */
+const PROXY_SCHEMES: Record<string, string> = {
+  http: "http",
+  https: "https",
+  socks: "socks5",
+  socks4: "socks4",
+  socks5: "socks5",
+  ss: "ss",
+  shadowsocks: "ss",
+  vless: "vless",
+};
+
+/** What a line carrying no scheme is assumed to be. */
+export const DEFAULT_PROXY_TYPE = "http";
+
+export const HOST_FIRST_FORMAT = "host:port:username:password";
+export const CREDENTIALS_FIRST_FORMAT = "username:password:host:port";
+
+/**
+ * Separates `socks5://1.2.3.4:1080` into its scheme and body. An unknown or
+ * absent scheme leaves the body untouched and falls back to HTTP, which is what
+ * the backend does with a bare `host:port`.
+ */
+export function splitProxyScheme(line: string): {
+  proxyType: string;
+  rest: string;
+} {
+  const separator = line.indexOf("://");
+  if (separator === -1) {
+    return { proxyType: DEFAULT_PROXY_TYPE, rest: line };
+  }
+
+  const proxyType = PROXY_SCHEMES[line.slice(0, separator).toLowerCase()];
+  return proxyType
+    ? { proxyType, rest: line.slice(separator + 3) }
+    : { proxyType: DEFAULT_PROXY_TYPE, rest: line };
+}
+
+/**
+ * Builds a proxy from a four-part line once the user has said which of the two
+ * orderings it uses. Returns null when the chosen ordering doesn't actually fit
+ * the line, so a stale selection can't produce a proxy pointing at a password.
+ */
+export function resolveAmbiguousProxyLine(
+  line: string,
+  format: string,
+): ParsedProxyLine | null {
+  const trimmed = line.trim();
+  const { proxyType, rest } = splitProxyScheme(trimmed);
+  const parts = rest.split(":");
+  if (parts.length !== 4) {
+    return null;
+  }
+
+  const hostFirst = format === HOST_FIRST_FORMAT;
+  if (!hostFirst && format !== CREDENTIALS_FIRST_FORMAT) {
+    return null;
+  }
+
+  const host = hostFirst ? parts[0] : parts[2];
+  const port = Number.parseInt(hostFirst ? parts[1] : parts[3], 10);
+  if (!host || !Number.isInteger(port) || port < 1 || port > 65535) {
+    return null;
+  }
+
+  return {
+    proxy_type: proxyType,
+    host,
+    port,
+    username: hostFirst ? parts[2] : parts[0],
+    password: hostFirst ? parts[3] : parts[1],
+    original_line: trimmed,
+  };
+}
+
+/**
+ * Picks the proxy to use out of a parse of pasted text. Only the first usable
+ * line matters: the form holds one proxy, and a paste that happens to carry a
+ * whole list should still fill it in rather than do nothing.
+ *
+ * Ambiguous lines resolve as `host:port:username:password`, the ordering the
+ * import dialog offers first and the one vendors overwhelmingly ship.
+ */
+export function pickParsedProxy(
+  results: ProxyParseResult[],
+): ParsedProxyLine | null {
+  for (const result of results) {
+    if (result.status === "parsed") {
+      return {
+        proxy_type: result.proxy_type,
+        host: result.host,
+        port: result.port,
+        username: result.username,
+        password: result.password,
+        vless_uri: result.vless_uri,
+        original_line: result.original_line,
+      };
+    }
+    if (result.status === "ambiguous") {
+      const resolved = resolveAmbiguousProxyLine(
+        result.line,
+        HOST_FIRST_FORMAT,
+      );
+      if (resolved) {
+        return resolved;
+      }
+    }
+  }
+  return null;
+}