From 1594d8d64753e9639cd31246628e9b642c9bb213 Mon Sep 17 00:00:00 2001
From: j3rem1e <jeremie.brebec@gmail.com>
Date: Thu, 31 Aug 2023 23:41:39 +0200
Subject: [PATCH] Allow 'meta' to be exported as const from module script

---
 README.md                           |  15 ++--
 src/parser/collect-stories.ts       |   4 +-
 src/parser/extract-stories.test.ts  |  26 +++++++
 src/parser/extract-stories.ts       | 106 +++++++++++++++++++---------
 src/parser/svelte-stories-loader.ts |   7 +-
 src/plugins/vite-svelte-csf.ts      |   4 +-
 stories/metaexport.stories.svelte   |  35 +++++++++
 7 files changed, 153 insertions(+), 44 deletions(-)
 create mode 100644 stories/metaexport.stories.svelte

diff --git a/README.md b/README.md
index 4c3594c..c5eaf6b 100644
--- a/README.md
+++ b/README.md
@@ -14,19 +14,24 @@ It supports:
 ## Example
 
 ```svelte
-<script>
-  import { Meta, Story, Template } from '@storybook/addon-svelte-csf';
-
+<script content="module">
   import Button from './Button.svelte';
 
+  export const meta = {
+    title: "Button",
+    component: Button
+  }
+</script>
+
+<script>
+  import { Story, Template } from '@storybook/addon-svelte-csf';
+
   let count = 0;
   function handleClick() {
     count += 1;
   }
 </script>
 
-<Meta title="Button" component={Button}/>
-
 <Template let:args>
   <Button {...args} on:click={handleClick}>
     You clicked: {count}
diff --git a/src/parser/collect-stories.ts b/src/parser/collect-stories.ts
index c69e420..f1fa5ba 100644
--- a/src/parser/collect-stories.ts
+++ b/src/parser/collect-stories.ts
@@ -35,7 +35,7 @@ const createFragment = document.createDocumentFragment
   ? () => document.createDocumentFragment()
   : () => document.createElement('div');
 
-export default (StoriesComponent, { stories = {}, allocatedIds = [] }) => {
+export default (StoriesComponent, { stories = {}, allocatedIds = [] }, exportedMeta = undefined) => {
   const repositories = {
     meta: null as Meta | null,
     stories: [] as Story[],
@@ -55,7 +55,7 @@ export default (StoriesComponent, { stories = {}, allocatedIds = [] }) => {
     logger.error(`Error extracting stories ${e.toString()}`, e);
   }
 
-  const { meta } = repositories;
+  let meta = exportedMeta || repositories.meta;
   if (!meta) {
     logger.error('Missing <Meta/> tag');
     return {};
diff --git a/src/parser/extract-stories.test.ts b/src/parser/extract-stories.test.ts
index 4dd3bda..bc90f22 100644
--- a/src/parser/extract-stories.test.ts
+++ b/src/parser/extract-stories.test.ts
@@ -339,6 +339,32 @@ describe('extractSource', () => {
       }
     `);
   });
+  test('Meta as exported module object', () => {
+    expect(
+      extractStories(`
+        <script context='module'>
+          export const meta = {
+            title: 'MyStory',
+            tags: ['a']
+          };
+        </script>
+        `)
+    ).toMatchInlineSnapshot(`
+      {
+        "allocatedIds": [
+          "default",
+        ],
+        "meta": {
+          "id": undefined,
+          "tags": [
+            "a",
+          ],
+          "title": "MyStory",
+        },
+        "stories": {},
+      }
+    `);
+  });
   test('Duplicate Id', () => {
     expect(
       extractStories(`
diff --git a/src/parser/extract-stories.ts b/src/parser/extract-stories.ts
index d9e8070..da5d063 100644
--- a/src/parser/extract-stories.ts
+++ b/src/parser/extract-stories.ts
@@ -23,18 +23,26 @@ interface StoriesDef {
   allocatedIds: string[];
 }
 
+function lookupAttribute(name: string, attributes: any[]) {
+  return attributes.find((att: any) => 
+    (att.type === 'Attribute' && att.name === name) || 
+    (att.type === 'Property' && att.key.name === name));
+}
+
 function getStaticAttribute(name: string, node: any): string | undefined {
   // extract the attribute
-  const attribute = node.attributes.find(
-    (att: any) => att.type === 'Attribute' && att.name === name
-  );
+  const attribute = lookupAttribute(name, node);
 
   if (!attribute) {
     return undefined;
   }
 
   const { value } = attribute;
-  // expect the attribute to be static, ie only one Text node
+  // expect the attribute to be static, ie only one Text node or Literal
+  if (value?.type === 'Literal') {
+    return value.value;
+  }
+
   if (value && value.length === 1 && value[0].type === 'Text') {
     return value[0].data;
   }
@@ -42,11 +50,10 @@ function getStaticAttribute(name: string, node: any): string | undefined {
   throw new Error(`Attribute ${name} is not static`);
 }
 
-function getStaticBooleanAttribute(name: string, node: any): boolean | undefined {
+function getStaticBooleanAttribute(name: string, attributes: any[]): boolean | undefined {
   // extract the attribute
-  const attribute = node.attributes.find(
-    (att: any) => att.type === 'Attribute' && att.name === name
-  );
+  const attribute = lookupAttribute(name, attributes);
+
 
   if (!attribute) {
     return undefined;
@@ -62,27 +69,35 @@ function getStaticBooleanAttribute(name: string, node: any): boolean | undefined
   throw new Error(`Attribute ${name} is not a static boolean`);
 }
 
-function getMetaTags(node: any): string[] {
+function getMetaTags(attributes: any[]): string[] {
+
+  const finalTags = getStaticBooleanAttribute('autodocs', attributes) ? ["autodocs"] : [];
 
-  const finalTags = getStaticBooleanAttribute('autodocs', node) ? ["autodocs"] : [];
+  const tags = lookupAttribute('tags', attributes);
 
-  const tags = node.attributes.find((att: any) => att.type === 'Attribute' && att.name === 'tags');
   if (tags) {
     let valid = false;
 
-    const { value } = tags;
-    if (value && value.length === 1 ) {
-      const { type, expression, data } = value[0];
-      if (type === 'Text') {
-        // tags="autodocs"
-        finalTags.push(data);
-        valid = true;
-      } else if (type === 'MustacheTag' && expression.type === 'ArrayExpression') {
-        // tags={["autodocs"]}
-        const { elements } = expression;
-        elements.forEach((e : any) => finalTags.push(e.value));
-        valid = true;
-      }
+    let { value } = tags;
+    if (value && value.length === 1) {
+      value = value[0];
+    }
+
+    const { type, expression, data } = value;
+    if (type === 'Text') {
+      // tags="autodocs"
+      finalTags.push(data);
+      valid = true;
+    } else if (type === 'ArrayExpression') {
+      // tags={["autodocs"]} in object
+      const { elements } = value;
+      elements.forEach((e : any) => finalTags.push(e.value));
+      valid = true;
+    } else if (type === 'MustacheTag' && expression.type === 'ArrayExpression') {
+      // tags={["autodocs"]} in template
+      const { elements } = expression;
+      elements.forEach((e : any) => finalTags.push(e.value));
+      valid = true;
     }
 
     if (!valid) {
@@ -93,6 +108,14 @@ function getMetaTags(node: any): string[] {
   return finalTags;
 }
 
+function fillMetaFromAttributes(meta: MetaDef, attributes: any[]) {
+  meta.title = getStaticAttribute('title', attributes);
+  meta.id = getStaticAttribute('id', attributes);
+  const tags = getMetaTags(attributes);
+  if (tags.length > 0) {
+    meta.tags = tags;
+  }
+}
 /**
  * Parse a Svelte component and extract stories.
  * @param component Component Source
@@ -142,6 +165,28 @@ export function extractStories(component: string): StoriesDef {
 
   const stories: Record<string, StoryDef> = {};
   const meta: MetaDef = {};
+  if (ast.module) {
+    svelte.walk(<Node>ast.module.content, {
+      enter(node: any) {
+        if (node.type === 'ExportNamedDeclaration' && 
+          node.declaration?.type === 'VariableDeclaration' && 
+          node.declaration?.declarations.length === 1 &&
+          node.declaration?.declarations[0]?.id?.name === 'meta') {
+
+            if (node.declaration?.kind !== 'const') {
+              throw new Error('meta should be exported as const');
+            }
+
+            const init = node.declaration?.declarations[0]?.init;
+            if (init?.type !== 'ObjectExpression') {
+              throw new Error('meta should export on object');
+            }
+
+            fillMetaFromAttributes(meta, init.properties);
+        }
+      }
+    });
+  }
   svelte.walk(<Node>ast.html, {
     enter(node: any) {
       if (
@@ -153,7 +198,7 @@ export function extractStories(component: string): StoriesDef {
         const isTemplate = node.name === 'Template';
 
         // extract the 'name' attribute
-        let name = getStaticAttribute('name', node);
+        let name = getStaticAttribute('name', node.attributes);
 
         // templates has a default name
         if (!name && isTemplate) {
@@ -162,7 +207,7 @@ export function extractStories(component: string): StoriesDef {
 
         const id = extractId(
           {
-            id: getStaticAttribute('id', node),
+            id: getStaticAttribute('id', node.attributes),
             name,
           },
           isTemplate ? undefined : allocatedIds
@@ -189,16 +234,11 @@ export function extractStories(component: string): StoriesDef {
       } else if (node.type === 'InlineComponent' && node.name === localNames.Meta) {
         this.skip();
 
-        meta.title = getStaticAttribute('title', node);
-        meta.id = getStaticAttribute('id', node);
-        const tags = getMetaTags(node);
-        if (tags.length > 0) {
-          meta.tags = tags;
-        }
+        fillMetaFromAttributes(meta, node.attributes);
       }
     },
   });
-
+  
   return {
     meta,
     stories,
diff --git a/src/parser/svelte-stories-loader.ts b/src/parser/svelte-stories-loader.ts
index 7b31ad0..41ac4c0 100644
--- a/src/parser/svelte-stories-loader.ts
+++ b/src/parser/svelte-stories-loader.ts
@@ -54,11 +54,12 @@ function transformSvelteStories(code: string) {
     .map(([id]) => `export const ${id} = __storiesMetaData.stories[${JSON.stringify(id)}]`)
     .join('\n');
 
-  const codeWithoutDefaultExport = code.replace('export default ', '//export default');
-
+  const metaExported = code.includes('export { meta }');
+  const codeWithoutDefaultExport = code.replace('export default ', '//export default').replace('export { meta };', '// export { meta };');
+  
   return `${codeWithoutDefaultExport}
     const { default: parser } = require('${parser}');
-    const __storiesMetaData = parser(${componentName}, ${JSON.stringify(storiesDef)});
+    const __storiesMetaData = parser(${componentName}, ${JSON.stringify(storiesDef)}${metaExported ? ', meta' : ''});
     export default __storiesMetaData.meta;
     ${storyDef};
   ` as string;
diff --git a/src/plugins/vite-svelte-csf.ts b/src/plugins/vite-svelte-csf.ts
index 968a17f..182d264 100644
--- a/src/plugins/vite-svelte-csf.ts
+++ b/src/plugins/vite-svelte-csf.ts
@@ -42,10 +42,12 @@ export default function csfPlugin(svelteOptions) {
         .filter(([, def]) => !def.template)
         .map(([storyId]) => storyId);
 
+      const metaExported = code.includes('export { meta }');
+      s.replace('export { meta };', '// export { meta };');
       const output = [
         '',
         `import parser from '${parser}';`,
-        `const __storiesMetaData = parser(${component}, ${JSON.stringify(all)});`,
+        `const __storiesMetaData = parser(${component}, ${JSON.stringify(all)}${metaExported ? ', meta' : ''});`,
         'export default __storiesMetaData.meta;',
         `export const __namedExportsOrder = ${JSON.stringify(namedExportsOrder)};`,
         storyDef,
diff --git a/stories/metaexport.stories.svelte b/stories/metaexport.stories.svelte
new file mode 100644
index 0000000..6d4e145
--- /dev/null
+++ b/stories/metaexport.stories.svelte
@@ -0,0 +1,35 @@
+<script context='module'>
+  import Button from './Button.svelte';
+
+  export const meta = {
+    title: 'MetaExport',
+    component: Button,
+    tags: ['autodocs']
+  }
+</script>
+
+<script>
+  import { Story, Template } from '../src/index';
+
+  let count = 0;
+  function handleClick() {
+    count += 1;
+  }
+</script>
+
+<Template let:args>
+  <Button {...args} on:click={handleClick}>
+    You clicked: {count}
+  </Button>
+</Template>
+
+<Story name="Default"/>
+
+<Story name="Rounded" args={{rounded: true}}/>
+
+<Story name="Square" source args={{rounded: false}}/>
+
+<!-- Dynamic snippet should be disabled for this story -->
+<Story name="Button No Args">
+  <Button>Label</Button>
+</Story>
\ No newline at end of file