webui_wasm/
lib.rs

1// Copyright (c) Microsoft Corporation.
2// Licensed under the MIT license.
3
4//! WebAssembly bindings for the WebUI framework.
5//!
6//! This crate exposes the WebUI rendering pipeline to JavaScript via `wasm-bindgen`,
7//! powering the interactive playground in the documentation site.
8//!
9//! Two modes of operation:
10//! - **`render`** — Takes a pre-built protocol (JSON) + state and renders HTML.
11//! - **`build_and_render`** — Takes virtual files + state, parses and renders HTML
12//!   using the real `webui-parser` (same parser used by the CLI).
13
14use serde_json::Value;
15use std::collections::HashMap;
16use wasm_bindgen::prelude::*;
17use webui_handler::plugin::fast::FastHydrationPlugin;
18use webui_handler::plugin::webui::WebUIHydrationPlugin;
19use webui_handler::{RenderOptions, ResponseWriter, WebUIHandler};
20use webui_parser::{CssStrategy, HtmlParser, Plugin};
21use webui_protocol::WebUIProtocol;
22
23/// A simple string buffer for collecting rendered output.
24struct StringWriter {
25    content: String,
26}
27
28impl StringWriter {
29    fn with_capacity(cap: usize) -> Self {
30        Self {
31            content: String::with_capacity(cap),
32        }
33    }
34}
35
36impl ResponseWriter for StringWriter {
37    fn write(&mut self, content: &str) -> webui_handler::Result<()> {
38        self.content.push_str(content);
39        Ok(())
40    }
41
42    fn end(&mut self) -> webui_handler::Result<()> {
43        Ok(())
44    }
45}
46
47/// Render a pre-built WebUI protocol with state data.
48///
49/// # Arguments
50///
51/// * `protocol_json` — JSON string of the serialized `WebUIProtocol`.
52/// * `state_json` — JSON string of the state data.
53/// * `plugin` — Optional plugin identifier.
54///
55/// # Returns
56///
57/// The rendered HTML string, or throws a JS error on failure.
58#[wasm_bindgen]
59pub fn render(
60    protocol_json: &str,
61    state_json: &str,
62    entry: &str,
63    request_path: &str,
64    plugin: Option<String>,
65) -> Result<String, JsValue> {
66    let plugin = plugin
67        .map(|s| s.parse::<Plugin>())
68        .transpose()
69        .map_err(|e| JsValue::from_str(&e))?;
70    render_inner(protocol_json, state_json, entry, request_path, plugin)
71        .map_err(|e| JsValue::from_str(&e.to_string()))
72}
73
74/// Build and render a WebUI application from virtual files.
75///
76/// Uses a lightweight pure-Rust parser suitable for the playground.
77/// Handles signals, for-loops, if-conditions, components, and dynamic attributes.
78///
79/// # Arguments
80///
81/// * `files` — A JS object mapping filenames to their string content.
82///   Example: `{ "index.html": "<h1>{{title}}</h1>", "my-card.html": "<p><slot></slot></p>" }`
83/// * `state_json` — A JSON string of the state data to render with.
84/// * `entry` — The entry HTML filename (e.g. `"index.html"`).
85///
86/// # Returns
87///
88/// The rendered HTML string, or throws a JS error on failure.
89#[wasm_bindgen]
90pub fn build_and_render(
91    files: JsValue,
92    state_json: &str,
93    entry: &str,
94    request_path: &str,
95) -> Result<String, JsValue> {
96    let files_map: HashMap<String, String> =
97        serde_wasm_bindgen::from_value(files).map_err(|e| JsValue::from_str(&e.to_string()))?;
98
99    build_and_render_inner(&files_map, state_json, entry, request_path)
100        .map_err(|e| JsValue::from_str(&e.to_string()))
101}
102
103/// Build the protocol JSON from virtual files without rendering.
104///
105/// Returns the serialized `WebUIProtocol` as a JSON string.
106#[wasm_bindgen]
107pub fn build_protocol(files: JsValue, entry: &str) -> Result<String, JsValue> {
108    let files_map: HashMap<String, String> =
109        serde_wasm_bindgen::from_value(files).map_err(|e| JsValue::from_str(&e.to_string()))?;
110
111    build_protocol_inner(&files_map, entry).map_err(|e| JsValue::from_str(&e.to_string()))
112}
113
114/// Produce a complete JSON partial response for client-side navigation.
115///
116/// Combines application state, route templates, inventory, request path, and
117/// matched route chain into a single JSON string:
118/// `{"state":{...},"templates":[...],"inventory":"...","path":"...","chain":[...]}`.
119///
120/// Host servers return this directly — no assembly required.
121#[wasm_bindgen]
122pub fn render_partial(
123    protocol_json: &str,
124    state_json: &str,
125    entry_id: &str,
126    request_path: &str,
127    inventory_hex: &str,
128) -> Result<String, JsValue> {
129    let protocol: WebUIProtocol = serde_json::from_str(protocol_json)
130        .map_err(|e| JsValue::from_str(&format!("Protocol JSON error: {e}")))?;
131
132    let state: serde_json::Value = serde_json::from_str(state_json)
133        .map_err(|e| JsValue::from_str(&format!("invalid state JSON: {e}")))?;
134
135    let result = webui_handler::route_handler::render_partial(
136        &protocol,
137        state,
138        entry_id,
139        request_path,
140        inventory_hex,
141    );
142
143    serde_json::to_string(&result)
144        .map_err(|e| JsValue::from_str(&format!("JSON serialize error: {e}")))
145}
146
147fn build_protocol_inner(
148    files: &HashMap<String, String>,
149    entry: &str,
150) -> Result<String, BuildError> {
151    let protocol = parse_to_protocol(files, entry)?;
152    serde_json::to_string(&protocol).map_err(|e| BuildError::Protocol(e.to_string()))
153}
154
155/// Create a handler with an optional plugin.
156fn create_handler(plugin: Option<Plugin>) -> Result<WebUIHandler, BuildError> {
157    match plugin {
158        Some(Plugin::Fast) => Ok(WebUIHandler::with_plugin(|| {
159            Box::new(FastHydrationPlugin::new())
160        })),
161        Some(Plugin::WebUI) => Ok(WebUIHandler::with_plugin(|| {
162            Box::new(WebUIHydrationPlugin::new())
163        })),
164        None => Ok(WebUIHandler::new()),
165    }
166}
167
168fn render_inner(
169    protocol_json: &str,
170    state_json: &str,
171    entry: &str,
172    request_path: &str,
173    plugin: Option<Plugin>,
174) -> Result<String, BuildError> {
175    let protocol: WebUIProtocol =
176        serde_json::from_str(protocol_json).map_err(|e| BuildError::Protocol(e.to_string()))?;
177    let state: Value =
178        serde_json::from_str(state_json).map_err(|e| BuildError::State(e.to_string()))?;
179
180    let mut writer = StringWriter::with_capacity(1024);
181    let handler = create_handler(plugin)?;
182    handler
183        .render(
184            &protocol,
185            &state,
186            &RenderOptions::new(entry, request_path),
187            &mut writer,
188        )
189        .map_err(|e| BuildError::Render(e.to_string()))?;
190
191    Ok(writer.content)
192}
193
194/// Core build-and-render implementation (testable without WASM).
195pub(crate) fn build_and_render_inner(
196    files: &HashMap<String, String>,
197    state_json: &str,
198    entry: &str,
199    request_path: &str,
200) -> Result<String, BuildError> {
201    let protocol = parse_to_protocol(files, entry)?;
202
203    let state: Value =
204        serde_json::from_str(state_json).map_err(|e| BuildError::State(e.to_string()))?;
205
206    let mut writer = StringWriter::with_capacity(1024);
207    let handler = create_handler(None)?;
208    handler
209        .render(
210            &protocol,
211            &state,
212            &RenderOptions::new(entry, request_path),
213            &mut writer,
214        )
215        .map_err(|e| BuildError::Render(e.to_string()))?;
216
217    Ok(writer.content)
218}
219
220/// Parse virtual files into a `WebUIProtocol` using the real `webui-parser`.
221fn parse_to_protocol(
222    files: &HashMap<String, String>,
223    entry: &str,
224) -> Result<WebUIProtocol, BuildError> {
225    let entry_html = files
226        .get(entry)
227        .ok_or_else(|| BuildError::MissingEntry(entry.to_string()))?;
228
229    let mut parser = HtmlParser::new();
230    parser.set_css_strategy(CssStrategy::Style);
231
232    // Register components from virtual files (no filesystem needed)
233    for (filename, content) in files {
234        if filename != entry && filename.ends_with(".html") {
235            let tag_name = filename.trim_end_matches(".html");
236            if tag_name.contains('-') {
237                let css_key = format!("{tag_name}.css");
238                let css = files.get(&css_key).map(|s| s.as_str());
239                parser
240                    .component_registry_mut()
241                    .register_component(tag_name, content, css)
242                    .map_err(|e| BuildError::Parse(e.to_string()))?;
243            }
244        }
245    }
246
247    parser
248        .parse(entry, entry_html)
249        .map_err(|e| BuildError::Parse(e.to_string()))?;
250
251    Ok(WebUIProtocol::new(parser.into_fragment_records()))
252}
253
254/// Errors from the build-and-render pipeline.
255#[derive(Debug, PartialEq)]
256pub(crate) enum BuildError {
257    MissingEntry(String),
258    Parse(String),
259    Protocol(String),
260    State(String),
261    Render(String),
262}
263
264impl std::fmt::Display for BuildError {
265    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
266        match self {
267            BuildError::MissingEntry(name) => write!(f, "Entry file '{name}' not found"),
268            BuildError::Parse(msg) => write!(f, "Parse error: {msg}"),
269            BuildError::Protocol(msg) => write!(f, "Protocol JSON error: {msg}"),
270            BuildError::State(msg) => write!(f, "State JSON error: {msg}"),
271            BuildError::Render(msg) => write!(f, "Render error: {msg}"),
272        }
273    }
274}
275
276#[cfg(test)]
277mod tests {
278    use super::*;
279
280    #[test]
281    fn test_simple_render() {
282        let mut files = HashMap::new();
283        files.insert(
284            "index.html".to_string(),
285            "<h1>Hello, {{name}}!</h1>".to_string(),
286        );
287
288        let result = build_and_render_inner(&files, r#"{"name": "WebUI"}"#, "index.html", "/");
289        assert!(result.is_ok(), "Render failed: {:?}", result);
290        assert_eq!(result.as_deref(), Ok("<h1>Hello, WebUI!</h1>"));
291    }
292
293    #[test]
294    fn test_missing_entry_file() {
295        let files = HashMap::new();
296        let result = build_and_render_inner(&files, "{}", "index.html", "/");
297        assert!(result.is_err());
298        let err = result.unwrap_err().to_string();
299        assert!(err.contains("not found"), "Unexpected error: {}", err);
300    }
301
302    #[test]
303    fn test_with_component() {
304        let mut files = HashMap::new();
305        files.insert(
306            "index.html".to_string(),
307            "<my-card>World</my-card>".to_string(),
308        );
309        files.insert(
310            "my-card.html".to_string(),
311            "<div class=\"card\"><slot></slot></div>".to_string(),
312        );
313
314        let result = build_and_render_inner(&files, "{}", "index.html", "/");
315        assert!(result.is_ok(), "Render failed: {:?}", result);
316        let html = result.as_deref().unwrap_or("");
317        assert!(html.contains("card"), "Expected card class in: {}", html);
318    }
319
320    #[test]
321    fn test_with_for_loop() {
322        let mut files = HashMap::new();
323        files.insert(
324            "index.html".to_string(),
325            "<for each=\"item in items\">{{item.name}}, </for>".to_string(),
326        );
327
328        let state = r#"{"items": [{"name": "A"}, {"name": "B"}]}"#;
329        let result = build_and_render_inner(&files, state, "index.html", "/");
330        assert!(result.is_ok(), "Render failed: {:?}", result);
331        let html = result.as_deref().unwrap_or("");
332        assert!(html.contains("A"), "Expected 'A' in: {}", html);
333        assert!(html.contains("B"), "Expected 'B' in: {}", html);
334    }
335
336    #[test]
337    fn test_with_if_condition() {
338        let mut files = HashMap::new();
339        files.insert(
340            "index.html".to_string(),
341            "<if condition=\"show\">Visible</if>".to_string(),
342        );
343
344        let result_true = build_and_render_inner(&files, r#"{"show": true}"#, "index.html", "/");
345        assert_eq!(result_true.as_deref(), Ok("Visible"));
346
347        let result_false = build_and_render_inner(&files, r#"{"show": false}"#, "index.html", "/");
348        assert_eq!(result_false.as_deref(), Ok(""));
349    }
350
351    #[test]
352    fn test_invalid_state_json() {
353        let mut files = HashMap::new();
354        files.insert("index.html".to_string(), "<p>Hi</p>".to_string());
355
356        let result = build_and_render_inner(&files, "not json", "index.html", "/");
357        assert!(result.is_err());
358        let err = result.unwrap_err().to_string();
359        assert!(
360            err.contains("State JSON error"),
361            "Unexpected error: {}",
362            err
363        );
364    }
365
366    #[test]
367    fn test_component_with_css() {
368        let mut files = HashMap::new();
369        files.insert(
370            "index.html".to_string(),
371            "<my-card>Content</my-card>".to_string(),
372        );
373        files.insert(
374            "my-card.html".to_string(),
375            "<p><slot></slot></p>".to_string(),
376        );
377        files.insert("my-card.css".to_string(), "p { color: red; }".to_string());
378
379        let result = build_and_render_inner(&files, "{}", "index.html", "/");
380        assert!(result.is_ok(), "Render failed: {:?}", result);
381        let html = result.as_deref().unwrap_or("");
382        // WASM uses CssStrategy::Style, so CSS should be in <style> tags, not <link>
383        assert!(
384            html.contains("<style>p { color: red; }</style>"),
385            "Expected inline <style> tag in: {}",
386            html
387        );
388        assert!(
389            !html.contains("<link"),
390            "Should not have external <link> tag in: {}",
391            html
392        );
393    }
394
395    #[test]
396    fn test_raw_signal() {
397        let mut files = HashMap::new();
398        files.insert(
399            "index.html".to_string(),
400            "<div>{{{raw_html}}}</div>".to_string(),
401        );
402
403        let result =
404            build_and_render_inner(&files, r#"{"raw_html": "<b>bold</b>"}"#, "index.html", "/");
405        assert!(result.is_ok(), "Render failed: {:?}", result);
406        let html = result.as_deref().unwrap_or("");
407        assert!(
408            html.contains("<b>bold</b>"),
409            "Expected raw HTML in: {}",
410            html
411        );
412    }
413
414    #[test]
415    fn test_static_html_passthrough() {
416        let mut files = HashMap::new();
417        files.insert(
418            "index.html".to_string(),
419            "<h1>Static</h1><p>Content</p>".to_string(),
420        );
421
422        let result = build_and_render_inner(&files, "{}", "index.html", "/");
423        assert_eq!(result.as_deref(), Ok("<h1>Static</h1><p>Content</p>"));
424    }
425}
webui_wasm/lib.rs

webui_wasm/
lib.rs
