Add base loader to resolve git dependencies

3 files changed, 152 insertions, 2 deletions

diff --git a/lib/template.js b/lib/template.js
index 315a373..76bb9ab 100644
--- a/lib/template.js
+++ b/lib/template.js
@@ -1,15 +1,50 @@
 var _ = require("lodash");
 var Q = require("q");
+var path = require("path");
 var nunjucks = require("nunjucks");
 
+var git = require("./utils/git");
+var fs = require("./utils/fs");
 var pkg = require("../package.json");
 
+
+// The loader should handle relative and git url
+var BookLoader = nunjucks.Loader.extend({
+	async: true,
+
+    init: function(book) {
+    	this.book = book;
+    },
+
+    getSource: function(fileurl, callback) {
+    	var that = this;
+
+		git.resolveFile(fileurl)
+		.then(function(filepath) {
+			// Is local file
+			if (!filepath) filepath = path.resolve(that.book.root, fileurl);
+			else that.book.logDebug("resolve from git", fileurl, "to", filepath)
+
+			//  Read file from absolute path
+			return fs.readFile(filepath)
+    		.then(function(source) {
+    			return {
+    				src: source.toString(),
+    				path: filepath
+    			}
+    		});
+		})
+		.nodeify(callback);
+    }
+});
+
+
 var TemplateEngine = function(book) {
 	this.book = book;
 
 	// Nunjucks env
 	this.env = new nunjucks.Environment(
-		new nunjucks.FileSystemLoader(book.root),
+		new BookLoader(book),
 		{
 			// Escaping is done after by the markdown parser
 			autoescape: false
diff --git a/lib/utils/fs.js b/lib/utils/fs.js
index 95fa73d..51577c6 100644
--- a/lib/utils/fs.js
+++ b/lib/utils/fs.js
@@ -1,5 +1,6 @@
 var Q = require("q");
-var fs = require('graceful-fs');
+var tmp = require("tmp");
+var fs = require("graceful-fs");
 var fsExtra = require("fs-extra");
 var Ignore = require("fstream-ignore");
 
@@ -62,6 +63,10 @@ var getFiles = function(path) {
 };
 
 module.exports = {
+    tmp: {
+        file: Q.denodeify(tmp.file.bind(tmp)),
+        dir: Q.denodeify(tmp.dir.bind(tmp))
+    },
     list: getFiles,
     stat: Q.denodeify(fs.stat),
     readdir: Q.denodeify(fs.readdir),
diff --git a/lib/utils/git.js b/lib/utils/git.js
new file mode 100644
index 0000000..8b515ec
--- /dev/null
+++ b/lib/utils/git.js
@@ -0,0 +1,110 @@
+var  Q = require("q");
+var _ = require("lodash");
+var url = require("url");
+var tmp = require("tmp");
+var path = require("path");
+var crc = require("crc");
+var exec = Q.denodeify(require("child_process").exec);
+
+var fs = require("./fs");
+
+var GIT_PREFIX = "git+";
+var GIT_TMP = null;
+
+
+// Check if an url is a git dependency url
+function checkGitUrl(giturl) {
+	return (giturl.indexOf(GIT_PREFIX) === 0);
+}
+
+// Validates a SHA in hexadecimal
+function validateSha(str) {
+    return (/[0-9a-f]{40}/).test(str);
+}
+
+// Parse and extract infos
+function parseGitUrl(giturl) {
+	if (!checkGitUrl(giturl)) return null;
+	giturl = giturl.slice(GIT_PREFIX.length);
+
+	var parts = url.parse(giturl);
+
+	var ref = parts.hash;
+
+	// Extract file inside the repo (after the .git)
+	var fileParts = parts.pathname.split(".git");
+	var filepath = fileParts.length > 1? fileParts.slice(1).join(".git") : "";
+	if (filepath[0] == "/") filepath = filepath.slice(1);
+
+	// Rebuild
+	parts.pathname = _.first(fileParts)+".git";
+	var githost = url.format(parts);
+
+	return {
+		host: githost,
+		ref: ref,
+		filepath: filepath
+	};
+}
+
+// Clone a git repo from a specific ref
+function cloneGitRepo(host, ref) {
+	var isBranch = false;
+
+	ref = ref || "master";
+	if (!validateSha(ref)) isBranch = true;
+
+	return Q()
+
+	// Create temporary folder to store git repos
+	.then(function() {
+		if (GIT_TMP) return;
+		return fs.tmp.dir().get(0)
+			.then(function(_tmp) {
+				GIT_TMP = _tmp;
+			});
+	})
+
+	// Return or clone the git repo
+	.then(function() {
+		// Unique ID for repo/ref combinaison
+		var repoId = crc.crc32(host+"#"+ref).toString(16);
+
+		// Absolute path to the folder
+		var repoPath = path.resolve(GIT_TMP, repoId);
+
+		return fs.exists(repoPath)
+			.then(function(doExists) {
+				if (doExists) return;
+
+				// Clone repo
+				return exec("git clone "+host+" "+repoPath)
+				.then(function() {
+					return exec("git checkout "+ref, { cwd: repoPath });
+				})
+			})
+			.thenResolve(repoPath);
+	});
+}
+
+
+// Get file from a git repo
+function resolveFileFromGit(giturl) {
+	if (_.isString(giturl)) giturl = parseGitUrl(giturl);
+	if (!giturl) return Q(null);
+
+	// Clone or get from cache
+	return cloneGitRepo(giturl.host, giturl.ref)
+	.then(function(repo) {
+
+		// Resolve relative path
+		return path.resolve(repo, giturl.filepath);
+	});
+};
+
+
+module.exports = {
+	checkUrl: checkGitUrl,
+	parseUrl: parseGitUrl,
+	resolveFile: resolveFileFromGit
+};