[Tokei] Implement a lines of code (LOC) badge (#5547)

* Implement LOC badge

* Apply suggestions from code review

Co-authored-by: Caleb Cartwright <calebcartwright@users.noreply.github.com>

* Fix tokei tests after API change

* Format the code

* Rename tokei service file

* Add comment about Tokei API behavior

* Document tokei badge behavior

Co-authored-by: Caleb Cartwright <calebcartwright@users.noreply.github.com>

services/tokei/tokei.service.js

@@ -0,0 +1,82 @@
+'use strict'
+
+const Joi = require('@hapi/joi')
+const { metric } = require('../text-formatters')
+const { nonNegativeInteger } = require('../validators')
+const { BaseJsonService } = require('..')
+
+const schema = Joi.object({
+  lines: nonNegativeInteger,
+}).required()
+
+const documentation = `
+<p>
+  The <code>provider</code> is the domain name of git host.
+  If no TLD is provided, <code>.com</code> will be added.
+  For example, setting <code>gitlab</code> or <code>bitbucket.org</code> as the
+  provider also works.
+  <br><br>
+  Tokei will automatically count all files with a recognized extension. It will
+  automatically ignore files and folders in <code>.ignore</code> files. If you
+  want to ignore files or folders specifically for tokei, add them to the
+  <code>.tokeignore</code> in the root of your repository.
+  See 
+    <a href="https://github.com/XAMPPRocky/tokei#excluding-folders">https://github.com/XAMPPRocky/tokei#excluding-folders</a>
+  for more info.
+</p>
+`
+
+module.exports = class Tokei extends BaseJsonService {
+  static category = 'size'
+
+  static route = { base: 'tokei/lines', pattern: ':provider/:user/:repo' }
+
+  static get examples() {
+    return [
+      {
+        title: 'Lines of code',
+        namedParams: {
+          provider: 'github',
+          user: 'badges',
+          repo: 'shields',
+        },
+        staticPreview: this.render({ lines: 119500 }),
+        keywords: ['loc', 'tokei'],
+        documentation,
+      },
+    ]
+  }
+
+  static defaultBadgeData = {
+    label: 'total lines',
+    color: 'blue',
+  }
+
+  static render({ lines }) {
+    return { message: metric(lines) }
+  }
+
+  async fetch({ provider, user, repo }) {
+    // This request uses the tokei-rs (https://github.com/XAMPPRocky/tokei_rs) API.
+    //
+    // By default, the API returns an svg, but when the Accept HTTP header is set to
+    // `application/json`, it sends json data. The `_requestJson` method
+    // automatically sets the Accept Header to what we need, so we don't need to
+    // specify it here.
+    //
+    // This behaviour of the API is "documented" here:
+    // https://github.com/XAMPPRocky/tokei_rs/issues/8#issuecomment-475071147
+    return this._requestJson({
+      schema,
+      url: `https://tokei.rs/b1/${provider}/${user}/${repo}`,
+      errorMessages: {
+        400: 'repo not found',
+      },
+    })
+  }
+
+  async handle({ provider, user, repo }) {
+    const { lines } = await this.fetch({ provider, user, repo })
+    return this.constructor.render({ lines })
+  }
+}

services/tokei/tokei.tester.js

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+'use strict'
+
+const { ServiceTester } = require('../tester')
+const { isMetric } = require('../test-validators')
+
+const t = new ServiceTester({ id: 'tokei', title: 'Tokei LOC Tests' })
+module.exports = t
+
+t.create('GitHub LOC')
+  .get('/lines/github/badges/shields.json')
+  .expectBadge({ label: 'total lines', message: isMetric })
+
+t.create('GitLab LOC')
+  .get('/lines/gitlab/tezos/tezos.json')
+  .expectBadge({ label: 'total lines', message: isMetric })
+
+t.create('GitHub LOC (with .com)')
+  .get('/lines/github.com/badges/shields.json')
+  .expectBadge({ label: 'total lines', message: isMetric })
+
+t.create('GitLab LOC (with .com)')
+  .get('/lines/gitlab.com/tezos/tezos.json')
+  .expectBadge({ label: 'total lines', message: isMetric })
+
+t.create('BitBucket LOC')
+  .get('/lines/bitbucket.org/MonliH/tokei-shields-test.json')
+  .expectBadge({ label: 'total lines', message: isMetric })
+
+t.create('Invalid Provider')
+  .get('/lines/example/tezos/tezos.json')
+  .expectBadge({ label: 'total lines', message: 'repo not found' })