Support relative local file paths

Inspired by textlint-rule/textlint-rule-no-dead-link-fork@f0063e9, thanks @azu!

Author: nodaguti

ReadMe.md

@@ -41,8 +41,13 @@ This error is fixable and textlint will automatically replace the obsolete links
 ### Relative Link Resolution
 
 Sometimes your files contain relative URIs, which don't have domain information in an URI string.
+In this case, we have to somehow resolve the relative URIs and convert them into absolute URIs.
 
-You can enable availability checks to such links by telling the rule how to resolve the relative links (See below for details).
+The resolution strategy is as follows:
+
+1. If `baseURI` is specified, use that path to resolve relative URIs (See the below section for details).
+2. If not, try to get the path of the file being linted and use its parent folder as the base path.
+3. If that's not available (e.g., when you are performing linting from API), put an error `Unable to resolve the relative URI`.
 
 ## Options
 
@@ -54,33 +59,30 @@ The default options are:
 {
   "rules": {
     "no-dead-link": {
-      "checkRelative": false,
       "baseURI": null,
       "ignore": [],
     }
   }
 }
 ```
 
-### checkRelative
-
-Enable the dead link checks against relative URIs.
-Note that you also have to specify the `baseURI` to make this option work.
-
 ### baseURI
 
 The base URI to be used for resolving relative URIs.
 
-Example:
+Though its name, you can pass either an URI starting with `http` or `https`, or an file path starting with `/`.
+
+Examples:
 
 ```
-{
-  "rules": {
-    "no-dead-link": {
-      "checkRelative": true,
-      "baseURI": "http://example.com/"
-    }
-  }
+"no-dead-link": {
+  "baseURI": "http://example.com/"
+}
+```
+
+```
+"no-dead-link": {
+  "baseURI": "/Users/textlint/path/to/parent/folder/"
 }
 ```
 

package.json

@@ -23,6 +23,7 @@
   "homepage": "https://github.com/textlint-rule/textlint-rule-no-dead-link",
   "repository": "textlint-rule/textlint-rule-no-dead-link",
   "dependencies": {
+    "fs-extra": "^5.0.0",
     "isomorphic-fetch": "^2.2.1",
     "textlint-rule-helper": "^2.0.0"
   },

src/no-dead-link.js

@@ -1,11 +1,13 @@
 import { RuleHelper } from 'textlint-rule-helper';
 import fetch from 'isomorphic-fetch';
 import URL from 'url';
+import path from 'path';
+import fs from 'fs-extra';
 
 const DEFAULT_OPTIONS = {
   checkRelative: false, // `true` enables availability checks for relative URIs.
-  baseURI: null, // a base URI to resolve relative URIs.
-  ignore: [], // URIs to be skipped from availability checks.
+  baseURI: null, // {String|null} a base URI to resolve relative URIs.
+  ignore: [], // {Array<String>} URIs to be skipped from availability checks.
 };
 
 // Adopted from http://stackoverflow.com/a/3809435/951517
@@ -20,6 +22,15 @@ function isRelative(uri) {
   return URL.parse(uri).protocol === null;
 }
 
+/**
+ * Returns if a given URI indicates a local file.
+ * @param {string} uri
+ * @return {boolean}
+ */
+function isLocal(uri) {
+  return isRelative(uri);
+}
+
 /**
  * Return `true` if the `code` is redirect status code.
  * @see https://fetch.spec.whatwg.org/#redirect-status
@@ -38,7 +49,7 @@ function isRedirect(code) {
  * @param {string} method
  * @return {{ ok: boolean, redirect?: string, message: string }}
  */
-async function isAlive(uri, method = 'HEAD') {
+async function isAliveURI(uri, method = 'HEAD') {
   const opts = {
     method,
     // Disable gzip compression in Node.js
@@ -76,7 +87,7 @@ async function isAlive(uri, method = 'HEAD') {
     // as some servers don't accept `HEAD` requests but are OK with `GET` requests.
     // https://github.com/textlint-rule/textlint-rule-no-dead-link/pull/86
     if (method === 'HEAD') {
-      return isAlive(uri, 'GET');
+      return isAliveURI(uri, 'GET');
     }
 
     return {
@@ -86,8 +97,26 @@ async function isAlive(uri, method = 'HEAD') {
   }
 }
 
+/**
+ * Check if a given file exists
+ */
+async function isAliveLocalFile(filePath) {
+  try {
+    await fs.access(filePath.replace(/[?#].*?$/, ''));
+
+    return {
+      ok: true,
+    };
+  } catch (ex) {
+    return {
+      ok: false,
+      message: ex.message,
+    };
+  }
+}
+
 function reporter(context, options = {}) {
-  const { Syntax, getSource, report, RuleError, fixer } = context;
+  const { Syntax, getSource, report, RuleError, fixer, getFilePath } = context;
   const helper = new RuleHelper(context);
   const opts = Object.assign({}, DEFAULT_OPTIONS, options);
 
@@ -103,22 +132,24 @@ function reporter(context, options = {}) {
     }
 
     if (isRelative(uri)) {
-      if (!opts.checkRelative) {
-        return;
-      }
+      const filePath = getFilePath();
+      const base = opts.baseURI || (filePath && path.dirname(filePath));
 
-      if (!opts.baseURI) {
-        const message = 'The base URI is not specified.';
+      if (!base) {
+        const message =
+          'Unable to resolve the relative URI. Please check if the base URI is correctly specified.';
 
-        report(node, new RuleError(message, { index: 0 }));
+        report(node, new RuleError(message, { index }));
         return;
       }
 
       // eslint-disable-next-line no-param-reassign
-      uri = URL.resolve(opts.baseURI, uri);
+      uri = URL.resolve(base, uri);
     }
 
-    const result = await isAlive(uri);
+    const result = isLocal(uri)
+      ? await isAliveLocalFile(uri)
+      : await isAliveURI(uri);
     const { ok, redirected, redirectTo, message } = result;
 
     if (!ok) {

test/fixtures/a.md

@@ -0,0 +1,4 @@
+* Good link: [b.md](b.md).
+* Good link: [./b.md](./b.md).
+* Good link: [b.md#hash](b.md#hash).
+* Good link: [b.md?param](b.md?param).

test/fixtures/b.md

@@ -0,0 +1,3 @@
+* Bad link: [../NOTFOUND](../NOTFOUND).
+* Bad link: [NOTFOUND](NOTFOUND).
+* Bad link: [/NOTFOUND_XXXX](/NOTFOUND_XXXX).

test/no-dead-link.js

@@ -1,5 +1,7 @@
 /* eslint-disable max-len */
 import TextlintTester from 'textlint-tester';
+import fs from 'fs';
+import path from 'path';
 import rule from '../src/no-dead-link';
 
 const tester = new TextlintTester();
@@ -34,6 +36,12 @@ tester.run('no-dead-link', rule, {
         ignore: ['https://example.com/404.html'],
       },
     },
+    {
+      text: fs.readFileSync(path.join(__dirname, 'fixtures/a.md'), 'utf-8'),
+      options: {
+        baseURI: path.join(__dirname, 'fixtures/'),
+      },
+    },
   ],
   invalid: [
     {
@@ -108,15 +116,13 @@ tester.run('no-dead-link', rule, {
     },
     {
       text:
-        'should throw "No base URI is provided" error if checkRelative is true but baseURI is undefined: [no base](index.html)',
-      options: {
-        checkRelative: true,
-      },
+        'should throw when a relative URI cannot be resolved: [test](./a.md).',
       errors: [
         {
-          message: 'The base URI is not specified.',
+          message:
+            'Unable to resolve the relative URI. Please check if the base URI is correctly specified.',
           line: 1,
-          column: 97,
+          column: 61,
         },
       ],
     },

yarn.lock

@@ -1449,6 +1449,14 @@ from@~0:
   version "0.1.3"
   resolved "https://registry.yarnpkg.com/from/-/from-0.1.3.tgz#ef63ac2062ac32acf7862e0d40b44b896f22f3bc"
 
+fs-extra@^5.0.0:
+  version "5.0.0"
+  resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-5.0.0.tgz#414d0110cdd06705734d055652c5411260c31abd"
+  dependencies:
+    graceful-fs "^4.1.2"
+    jsonfile "^4.0.0"
+    universalify "^0.1.0"
+
 fs-readdir-recursive@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/fs-readdir-recursive/-/fs-readdir-recursive-1.0.0.tgz#8cd1745c8b4f8a29c8caec392476921ba195f560"
@@ -1574,7 +1582,7 @@ globby@^5.0.0:
     pify "^2.0.0"
     pinkie-promise "^2.0.0"
 
-graceful-fs@^4.1.2, graceful-fs@^4.1.4:
+graceful-fs@^4.1.2, graceful-fs@^4.1.4, graceful-fs@^4.1.6:
   version "4.1.11"
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.1.11.tgz#0e8bdfe4d1ddb8854d64e04ea7c00e2a026e5658"
 
@@ -2036,6 +2044,12 @@ json5@^0.5.0, json5@^0.5.1:
   version "0.5.1"
   resolved "https://registry.yarnpkg.com/json5/-/json5-0.5.1.tgz#1eade7acc012034ad84e2396767ead9fa5495821"
 
+jsonfile@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-4.0.0.tgz#8771aae0799b64076b76640fca058f9c10e33ecb"
+  optionalDependencies:
+    graceful-fs "^4.1.6"
+
 jsonify@~0.0.0:
   version "0.0.0"
   resolved "https://registry.yarnpkg.com/jsonify/-/jsonify-0.0.0.tgz#2c74b6ee41d93ca51b7b5aaee8f503631d252a73"
@@ -3507,6 +3521,10 @@ unist-util-visit@^1.1.0:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/unist-util-visit/-/unist-util-visit-1.1.1.tgz#e917a3b137658b335cb4420c7da2e74d928e4e94"
 
+universalify@^0.1.0:
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/universalify/-/universalify-0.1.1.tgz#fa71badd4437af4c148841e3b3b165f9e9e590b7"
+
 user-home@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/user-home/-/user-home-1.1.1.tgz#2b5be23a32b63a7c9deb8d0f28d485724a3df190"