1 files changed, 235 insertions, 0 deletions
diff --git a/src/content/dependencies/index.js b/src/content/dependencies/index.js
new file mode 100644
index 00000000..1210d78e
--- /dev/null
+++ b/src/content/dependencies/index.js
@@ -0,0 +1,235 @@
+import chokidar from 'chokidar';
+import EventEmitter from 'events';
+import * as path from 'path';
+import {ESLint} from 'eslint';
+import {fileURLToPath} from 'url';
+
+import contentFunction from '../../content-function.js';
+import {color, logWarn} from '../../util/cli.js';
+import {annotateFunction} from '../../util/sugar.js';
+
+function cachebust(filePath) {
+  if (filePath in cachebust.cache) {
+    cachebust.cache[filePath] += 1;
+    return `${filePath}?cachebust${cachebust.cache[filePath]}`;
+  } else {
+    cachebust.cache[filePath] = 0;
+    return filePath;
+  }
+}
+
+cachebust.cache = Object.create(null);
+
+export function watchContentDependencies({
+  mock = null,
+  logging = true,
+} = {}) {
+  const events = new EventEmitter();
+  const contentDependencies = {};
+
+  let emittedReady = false;
+  let initialScanComplete = false;
+  let allDependenciesFulfilled = false;
+
+  Object.assign(events, {
+    contentDependencies,
+    close,
+  });
+
+  const eslint = new ESLint();
+
+  // Watch adjacent files
+  const metaPath = fileURLToPath(import.meta.url);
+  const metaDirname = path.dirname(metaPath);
+  const watcher = chokidar.watch(metaDirname);
+
+  watcher.on('all', (event, filePath) => {
+    if (!['add', 'change'].includes(event)) return;
+    if (filePath === metaPath) return;
+    handlePathUpdated(filePath);
+  });
+
+  watcher.on('unlink', (filePath) => {
+    if (filePath === metaPath) {
+      console.error(`Yeowzers content dependencies just got nuked.`);
+      return;
+    }
+    handlePathRemoved(filePath);
+  });
+
+  watcher.on('ready', () => {
+    initialScanComplete = true;
+    checkReadyConditions();
+  });
+
+  if (mock) {
+    const errors = [];
+    for (const [functionName, spec] of Object.entries(mock)) {
+      try {
+        const fn = processFunctionSpec(functionName, spec);
+        contentDependencies[functionName] = fn;
+      } catch (error) {
+        error.message = `(${functionName}) ${error.message}`;
+        errors.push(error);
+      }
+    }
+    if (errors.length) {
+      throw new AggregateError(errors, `Errors processing mocked content functions`);
+    }
+    checkReadyConditions();
+  }
+
+  return events;
+
+  async function close() {
+    return watcher.close();
+  }
+
+  function checkReadyConditions() {
+    if (emittedReady) {
+      return;
+    }
+
+    if (!initialScanComplete) {
+      return;
+    }
+
+    checkAllDependenciesFulfilled();
+
+    if (!allDependenciesFulfilled) {
+      return;
+    }
+
+    events.emit('ready');
+    emittedReady = true;
+  }
+
+  function checkAllDependenciesFulfilled() {
+    allDependenciesFulfilled = !Object.values(contentDependencies).includes(null);
+  }
+
+  function getFunctionName(filePath) {
+    const shortPath = path.basename(filePath);
+    const functionName = shortPath.slice(0, -path.extname(shortPath).length);
+    return functionName;
+  }
+
+  function isMocked(functionName) {
+    return !!mock && Object.keys(mock).includes(functionName);
+  }
+
+  async function handlePathRemoved(filePath) {
+    const functionName = getFunctionName(filePath);
+    if (isMocked(functionName)) return;
+
+    delete contentDependencies[functionName];
+  }
+
+  async function handlePathUpdated(filePath) {
+    const functionName = getFunctionName(filePath);
+    if (isMocked(functionName)) return;
+
+    let error = null;
+
+    main: {
+      const eslintResults = await eslint.lintFiles([filePath]);
+      const eslintFormatter = await eslint.loadFormatter('stylish');
+      const eslintResultText = eslintFormatter.format(eslintResults);
+      if (eslintResultText.trim().length) {
+        console.log(eslintResultText);
+      }
+
+      let spec;
+      try {
+        spec = (await import(cachebust(filePath))).default;
+      } catch (caughtError) {
+        error = caughtError;
+        error.message = `Error importing: ${error.message}`;
+        break main;
+      }
+
+      let fn;
+      try {
+        fn = processFunctionSpec(functionName, spec);
+      } catch (caughtError) {
+        error = caughtError;
+        break main;
+      }
+
+      if (logging && initialScanComplete) {
+        const timestamp = new Date().toLocaleString('en-US', {timeStyle: 'medium'});
+        console.log(color.green(`[${timestamp}] Updated ${functionName}`));
+      }
+
+      contentDependencies[functionName] = fn;
+
+      events.emit('update', functionName);
+      checkReadyConditions();
+    }
+
+    if (!error) {
+      return true;
+    }
+
+    if (!(functionName in contentDependencies)) {
+      contentDependencies[functionName] = null;
+    }
+
+    events.emit('error', functionName, error);
+
+    if (logging) {
+      if (contentDependencies[functionName]) {
+        logWarn`Failed to import ${functionName} - using existing version`;
+      } else {
+        logWarn`Failed to import ${functionName} - no prior version loaded`;
+      }
+
+      if (typeof error === 'string') {
+        console.error(color.yellow(error));
+      } else {
+        console.error(error);
+      }
+    }
+
+    return false;
+  }
+
+  function processFunctionSpec(functionName, spec) {
+    if (typeof spec.data === 'function') {
+      annotateFunction(spec.data, {name: functionName, description: 'data'});
+    }
+
+    if (typeof spec.generate === 'function') {
+      annotateFunction(spec.generate, {name: functionName});
+    }
+
+    let fn;
+    try {
+      fn = contentFunction(spec);
+    } catch (error) {
+      error.message = `Error loading spec: ${error.message}`;
+      throw error;
+    }
+
+    return fn;
+  }
+}
+
+export function quickLoadContentDependencies(opts) {
+  return new Promise((resolve, reject) => {
+    const watcher = watchContentDependencies(opts);
+
+    watcher.on('error', (name, error) => {
+      watcher.close().then(() => {
+        error.message = `Error loading dependency ${name}: ${error}`;
+        reject(error);
+      });
+    });
+
+    watcher.on('ready', () => {
+      watcher.close().then(() => {
+        resolve(watcher.contentDependencies);
+      });
+    });
+  });
+}