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background.js
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background.js
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(function() {
"use strict";
var EMACS_EDIT_SERVICE = 'http://127.0.0.1:9292/edit';
var extName = chrome.app.getDetails().name;
// Set up context menu at install time.
chrome.runtime.onInstalled.addListener(function() {
chrome.contextMenus.create(
{id: extName, title: extName, contexts: ["all"]});
chrome.commands.getAll(updateShortcut);
});
chrome.contextMenus.onClicked.addListener(function(_, tab) {
onActivate(tab);
});
chrome.browserAction.onClicked.addListener(onActivate);
function updateShortcut(cmds) {
var t = extName;
var s = cmds && cmds[0] && cmds[0].shortcut;
if (s) {
t += ' - ' + s;
}
chrome.browserAction.setTitle({title: t});
}
//////////////// Session-based promises. ////////////////
function onActivate(tab) {
Promise.resolve({url: tab.url})
.then(injectHelper)
.then(sleep)
.then(getText)
.then(emacsEdit)
.then(setText)
.catch(showErr);
}
function showErr(session) {
console.log('showErr', session);
session.html = chrome.extension.getURL('error.html');
session.type = 'err';
execFn(remoteDispatch, session).catch(function() { alert(session.err); });
}
function injectHelper(session) {
var src = chrome.extension.getURL('injected.js');
return execFn(remoteInject, src).then(function() { return session; });
}
// TODO(wdm) Poll for injected.js being ready.
function sleep(session) {
return new Promise(function(resolve) {
window.setTimeout(function() { resolve(session); }, 300);
});
}
const sendPing = () => execFn(remoteDispatch, {type:'ping'})
// Doesn't resolve until emacs has sent response.
function emacsEdit(session) {
console.log('sending to emacs', session);
const pinger = setInterval(sendPing, 10*1000)
var opts = {
method: 'post',
headers: {
"Content-type": "text/plain",
"x-url": session.url,
"x-id": session.id // TODO(wdm) What is this for?
},
body: session.text
};
return fetch(EMACS_EDIT_SERVICE, opts)
.then(function(r) {
if (r.status === 200) {
return r.text().then(function(text) {
session.text = text;
return session;
});
} else {
throw new Error(r.statusText); // Never seen this happen.
}
})
.catch(function(err) {
session.err = 'NoEmacs';
return Promise.reject(session);
}).finally( () => clearInterval(pinger) )
}
function getText(session) {
return execFn(remoteDispatch, {type: 'get'})
.then(function() {
return execFn(remoteGetText)
.then(function(data) {
if (!data.editor) {
session.err = 'NoEditor';
return Promise.reject(session);
}
session.text = data.text;
session.id = data.id;
session.editor = data.editor;
return session;
});
});
}
function setText(session) {
session.type = 'set';
return execFn(remoteDispatch, session).then(function() { return session; });
}
////////////////////// Remote execution //////////////////////
// Convert fn to a string and execute it in the tab context.
function execFn(fn, args) {
var code = 'JSON.stringify((' + fn.toString() + ')(' +
JSON.stringify(args) + '));';
return new Promise(function(resolve, reject) {
var cb = function(r) {
if (chrome.runtime.lastError) {
reject({err: chrome.runtime.lastError.message});
} else {
resolve(JSON.parse(r && r[0]));
}
};
// console.warn('exec code ', code);
chrome.tabs.executeScript({code: code}, cb);
});
}
// Add injected.js once to a page.
function remoteInject(src) {
if (!document.getElementById('EmacsEdit')) {
var s = document.createElement('script');
s.src = src;
s.id = 'EmacsEdit';
document.body.appendChild(s);
}
}
// Read the text to edit from the DOM.
function remoteGetText() {
var msgEl = document.getElementById('EmacsEdit');
return {
text: msgEl.dataset.text,
editor: msgEl.dataset.editor,
id: msgEl.dataset.id
};
}
// Dispatch an event to injected.js.
function remoteDispatch(args) {
document.dispatchEvent(
new CustomEvent('EmacsEvent', {detail: JSON.stringify(args)}));
}
})();