From ac8b40a2f3a50bb30f121dcc1a454074498e7bf7 Mon Sep 17 00:00:00 2001
From: Shin'ya Ueoka <ueokande@i-beam.org>
Date: Sun, 17 Sep 2017 10:52:09 +0900
Subject: [PATCH] pagenate by prev/next links

---
 README.md                      |  2 +-
 src/background/keys.js         |  2 ++
 src/content/index.js           |  4 +++
 src/content/navigates.js       | 41 +++++++++++++++++++++++++++-
 src/operations/index.js        |  2 ++
 test/content/navigates.test.js | 50 ++++++++++++++++++++++++++++++++++
 6 files changed, 99 insertions(+), 2 deletions(-)
 create mode 100644 test/content/navigates.test.js

diff --git a/README.md b/README.md
index 84cf2a2..c163901 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ Firefox by WebExtensions API.
   - [ ] find a keyword in the page
 - [ ] navigations
   - [ ] yank/paste page
-  - [ ] pagenation
+  - [x] pagenation
   - [ ] open parent page
 - [ ] hints
   - [x] open a link
diff --git a/src/background/keys.js b/src/background/keys.js
index 577f023..2549c8d 100644
--- a/src/background/keys.js
+++ b/src/background/keys.js
@@ -30,6 +30,8 @@ const defaultKeymap = {
   'F': { type: operations.FOLLOW_START, newTab: true },
   'H': { type: operations.NAVIGATE_HISTORY_PREV },
   'L': { type: operations.NAVIGATE_HISTORY_NEXT },
+  '[[': { type: operations.NAVIGATE_LINK_PREV },
+  ']]': { type: operations.NAVIGATE_LINK_NEXT },
 };
 
 const asKeymapChars = (keys) => {
diff --git a/src/content/index.js b/src/content/index.js
index be01089..0e4f7e1 100644
--- a/src/content/index.js
+++ b/src/content/index.js
@@ -39,6 +39,10 @@ const execOperation = (operation) => {
     return navigates.historyPrev(window);
   case operations.NAVIGATE_HISTORY_NEXT:
     return navigates.historyNext(window);
+  case operations.NAVIGATE_LINK_PREV:
+    return navigates.linkPrev(window);
+  case operations.NAVIGATE_LINK_NEXT:
+    return navigates.linkNext(window);
   }
 };
 
diff --git a/src/content/navigates.js b/src/content/navigates.js
index 28f34c5..b68052d 100644
--- a/src/content/navigates.js
+++ b/src/content/navigates.js
@@ -1,8 +1,47 @@
+const PREV_LINK_PATTERNS = [
+  /\bprev\b/i, /\bprevious\b/i, /\bback\b/i,
+  /</, /\u2039/, /\u2190/, /\xab/, /\u226a/, /<</
+];
+const NEXT_LINK_PATTERNS = [
+  /\bnext\b/i,
+  />/, /\u203a/, /\u2192/, /\xbb/, /\u226b/, />>/
+];
+
+const findLinkByPatterns = (win, patterns) => {
+  let links = win.document.getElementsByTagName('a');
+  return Array.prototype.find.call(links, (link) => {
+    return patterns.some(ptn => ptn.test(link.textContent));
+  });
+};
+
 const historyPrev = (win) => {
   win.history.back();
 };
+
 const historyNext = (win) => {
   win.history.forward();
 };
 
-export { historyPrev, historyNext };
+const linkPrev = (win) => {
+  let link = win.document.querySelector('a[rel=prev]');
+  if (link) {
+    return link.click();
+  }
+  link = findLinkByPatterns(win, PREV_LINK_PATTERNS);
+  if (link) {
+    link.click();
+  }
+};
+
+const linkNext = (win) => {
+  let link = win.document.querySelector('a[rel=next]');
+  if (link) {
+    return link.click();
+  }
+  link = findLinkByPatterns(win, NEXT_LINK_PATTERNS);
+  if (link) {
+    link.click();
+  }
+};
+
+export { historyPrev, historyNext, linkPrev, linkNext };
diff --git a/src/operations/index.js b/src/operations/index.js
index 6d8cc7e..bb19df8 100644
--- a/src/operations/index.js
+++ b/src/operations/index.js
@@ -13,6 +13,8 @@ export default {
   FOLLOW_START: 'follow.start',
   NAVIGATE_HISTORY_PREV: 'navigate.history.prev',
   NAVIGATE_HISTORY_NEXT: 'navigate.history.next',
+  NAVIGATE_LINK_PREV: 'navigate.link.prev',
+  NAVIGATE_LINK_NEXT: 'navigate.link.next',
 
   // Background
   TABS_CLOSE: 'tabs.close',
diff --git a/test/content/navigates.test.js b/test/content/navigates.test.js
new file mode 100644
index 0000000..21c2a23
--- /dev/null
+++ b/test/content/navigates.test.js
@@ -0,0 +1,50 @@
+import { expect } from "chai";
+import * as navigates from '../../src/content/navigates';
+
+describe('navigates module', () => {
+  beforeEach(() => {
+  });
+
+  describe('#linkPrev', () => {
+    it('clicks prev link by text content', (done) => {
+      document.body.innerHTML = '<a href="#dummy">xprevx</a>  <a href="#prev">go to prev</a>';
+      navigates.linkPrev(window);
+      setTimeout(() => {
+        expect(document.location.hash).to.equal('#prev');
+        done();
+      }, 0);
+    });
+
+    it('clicks a[rel=prev] element preferentially', (done) => {
+      document.body.innerHTML = '<a href="#dummy">prev</a>  <a rel="prev" href="#prev">rel</a>';
+      navigates.linkPrev(window);
+      setTimeout(() => {
+        expect(document.location.hash).to.equal('#prev');
+        done();
+      }, 0);
+    });
+  });
+
+
+  describe('#linkNext', () => {
+    it('clicks next link by text content', (done) => {
+      document.body.innerHTML = '<a href="#dummy">xnextx</a>  <a href="#next">go to next</a>';
+      navigates.linkNext(window);
+      setTimeout(() => {
+        expect(document.location.hash).to.equal('#next');
+        done();
+      }, 0);
+    });
+
+    it('clicks a[rel=next] element preferentially', (done) => {
+      document.body.innerHTML = '<a href="#dummy">next</a>  <a rel="next" href="#next">rel</a>';
+      navigates.linkNext(window);
+      setTimeout(() => {
+        expect(document.location.hash).to.equal('#next');
+        done();
+      }, 0);
+    });
+  });
+});
+
+