feat: resolve parameterized shortlink URLs

tests/templates.test.ts

@@ -0,0 +1,103 @@
+import { describe, expect, it } from 'vitest';
+import { resolveTemplateUrl, TemplateResolutionError } from '../worker/lib/templates';
+
+function params(query = ''): URLSearchParams {
+  return new URLSearchParams(query);
+}
+
+describe('resolveTemplateUrl', () => {
+  it('returns a URL without template placeholders unchanged', () => {
+    expect(
+      resolveTemplateUrl({
+        targetUrl: 'https://example.com/static/path?x=1#hash',
+        query: params(),
+      }),
+    ).toBe('https://example.com/static/path?x=1#hash');
+  });
+
+  it('uses a default value when no override is provided', () => {
+    expect(
+      resolveTemplateUrl({
+        targetUrl: 'https://google.com/search?q={query,default=hello}',
+        query: params(),
+      }),
+    ).toBe('https://google.com/search?q=hello');
+  });
+
+  it('uses pathParam for the first template variable', () => {
+    expect(
+      resolveTemplateUrl({
+        targetUrl: 'https://en.wikipedia.org/wiki/{topic,default=Python}',
+        pathParam: 'Django',
+        query: params(),
+      }),
+    ).toBe('https://en.wikipedia.org/wiki/Django');
+  });
+
+  it('lets matching query params override pathParam and defaults', () => {
+    expect(
+      resolveTemplateUrl({
+        targetUrl: 'https://example.com/search?q={query,default=hello}',
+        pathParam: 'from-path',
+        query: params('query=from query'),
+      }),
+    ).toBe('https://example.com/search?q=from%20query');
+  });
+
+  it('resolves multiple params from query/default values', () => {
+    expect(
+      resolveTemplateUrl({
+        targetUrl: 'https://example.com/{locale,default=en}/search?q={query}&page={page,default=1}',
+        query: params('query=Django tips&page=2'),
+      }),
+    ).toBe('https://example.com/en/search?q=Django%20tips&page=2');
+  });
+
+  it('throws a typed error for a missing required param', () => {
+    expect(() =>
+      resolveTemplateUrl({
+        targetUrl: 'https://example.com/search?q={query}',
+        query: params(),
+      }),
+    ).toThrow(TemplateResolutionError);
+    expect(() =>
+      resolveTemplateUrl({
+        targetUrl: 'https://example.com/search?q={query}',
+        query: params(),
+      }),
+    ).toThrow('No value provided for template parameter "query"');
+  });
+
+  it('throws a typed error for invalid parameter names', () => {
+    expect(() =>
+      resolveTemplateUrl({
+        targetUrl: 'https://example.com/search?q={bad-name,default=hello}',
+        query: params(),
+      }),
+    ).toThrow(TemplateResolutionError);
+    expect(() =>
+      resolveTemplateUrl({
+        targetUrl: 'https://example.com/search?q={bad-name,default=hello}',
+        query: params(),
+      }),
+    ).toThrow('Invalid template parameter name "bad-name"');
+  });
+
+  it('preserves static Chinese text around params and encodes only substituted values', () => {
+    expect(
+      resolveTemplateUrl({
+        targetUrl: 'https://chatgpt.com/?q=翻译: {query,default=hello} 保证真实性',
+        query: params('query=cool beans'),
+      }),
+    ).toBe('https://chatgpt.com/?q=翻译: cool%20beans 保证真实性');
+  });
+
+  it('splits defaults only on the first comma', () => {
+    expect(
+      resolveTemplateUrl({
+        targetUrl: 'https://google.com/search?q={query,default=hello,world}',
+        query: params(),
+      }),
+    ).toBe('https://google.com/search?q=hello%2Cworld');
+  });
+});