4 files changed, 135 insertions, 0 deletions
diff --git a/src/background/index.js b/src/background/index.js
new file mode 100644
index 0000000..604ea92
--- /dev/null
+++ b/src/background/index.js
@@ -0,0 +1,46 @@
+import * as actions from '../shared/actions';
+import * as tabs from './tabs';
+import KeyQueue from './key-queue';
+
+const queue = new KeyQueue();
+
+const keyDownHandle = (request) => {
+  return queue.push({
+    code: request.code,
+    shift: request.shift,
+    ctrl: request.ctrl,
+    alt: request.alt,
+    meta: request.meta
+  })
+}
+
+const doBackgroundAction = (sender, action) => {
+  switch(action[0]) {
+  case actions.TABS_PREV:
+    tabs.selectPrevTab(sender.tab.index, actions[1] || 1);
+    break;
+  case actions.TABS_NEXT:
+    tabs.selectNextTab(sender.tab.index, actions[1] || 1);
+    break;
+  }
+}
+
+browser.runtime.onMessage.addListener((request, sender, sendResponse) => {
+  let action = null;
+
+  switch (request.type) {
+  case 'event.keydown':
+    action = keyDownHandle(request);
+    break;
+  }
+
+  if (action == null) {
+    return;
+  }
+
+  if (actions.isBackgroundAction(action[0])) {
+    doBackgroundAction(sender, action);
+  } else if (actions.isContentAction(action[0])) {
+    sendResponse(action);
+  }
+});
diff --git a/src/background/key-queue.js b/src/background/key-queue.js
new file mode 100644
index 0000000..e21399e
--- /dev/null
+++ b/src/background/key-queue.js
@@ -0,0 +1,38 @@
+import * as keys from './keys';
+import * as actions from '../shared/actions';
+
+const DEFAULT_KEYMAP = [
+  { keys: [{ code: KeyboardEvent.DOM_VK_K }], action: [ actions.SCROLL_UP, 1 ]},
+  { keys: [{ code: KeyboardEvent.DOM_VK_J }], action: [ actions.SCROLL_DOWN, 1 ]},
+  { keys: [{ code: KeyboardEvent.DOM_VK_G }, { code: KeyboardEvent.DOM_VK_G }], action: [ actions.SCROLL_TOP ]},
+  { keys: [{ code: KeyboardEvent.DOM_VK_G, shift: true }], action: [ actions.SCROLL_BOTTOM ]},
+  { keys: [{ code: KeyboardEvent.DOM_VK_H }], action: [ actions.TABS_PREV, 1 ]},
+  { keys: [{ code: KeyboardEvent.DOM_VK_L }], action: [ actions.TABS_NEXT, 1 ]},
+]
+
+export default class KeyQueue {
+
+  constructor(keymap) {
+    this.data = [];
+    this.keymap = keymap;
+  }
+
+  push(key) {
+    this.data.push(key);
+    let filtered = DEFAULT_KEYMAP.filter((map) => {
+      return keys.hasPrefix(map.keys, this.data)
+    });
+
+    if (filtered.length == 0) {
+      this.data = [];
+      return;
+    } else if (filtered.length == 1) {
+      let map = filtered[0];
+      if (map.keys.length == this.data.length) {
+        this.data = [];
+        return map.action;
+      }
+    }
+    return null;
+  }
+}
diff --git a/src/background/keys.js b/src/background/keys.js
new file mode 100644
index 0000000..2fd00a2
--- /dev/null
+++ b/src/background/keys.js
@@ -0,0 +1,28 @@
+const identifyKey = (key1, key2) => {
+  return (key1.code === key2.code) &&
+    ((key1.shift || false) === (key2.shift || false)) &&
+    ((key1.ctrl || false) === (key2.ctrl || false)) &&
+    ((key1.alt || false) === (key2.alt || false)) &&
+    ((key1.meta || false) === (key2.meta || false));
+};
+
+const hasPrefix = (keys, prefix) => {
+  if (keys.length < prefix.length) {
+    return false;
+  }
+  for (let i = 0; i < prefix.length; ++i) {
+    if (!identifyKey(keys[i], prefix[i])) {
+      return false;
+    }
+  }
+  return true;
+}
+
+const identifyKeys = (keys1, keys2) => {
+  if (keys1.length !== keys2.length) {
+    return false;
+  }
+  return hasPrefix(keys1, keys2);
+}
+
+export { identifyKey, identifyKeys, hasPrefix };
diff --git a/src/background/tabs.js b/src/background/tabs.js
new file mode 100644
index 0000000..000bd7d
--- /dev/null
+++ b/src/background/tabs.js
@@ -0,0 +1,23 @@
+const selectPrevTab = (current, count) => {
+  chrome.tabs.query({ currentWindow: true }, (tabs) => {
+    if (tabs.length < 2) {
+      return;
+    }
+    let select = (current - count) % tabs.length
+    let id = tabs[select].id;
+    chrome.tabs.update(id, { active: true })
+  });
+};
+
+const selectNextTab = (current, count) => {
+  chrome.tabs.query({ currentWindow: true }, (tabs) => {
+    if (tabs.length < 2) {
+      return;
+    }
+    let select = (current + count + tabs.length) % tabs.length
+    let id = tabs[select].id;
+    chrome.tabs.update(id, { active: true })
+  });
+};
+
+export { selectNextTab, selectPrevTab };