layerindex.bbclass: Add ability to fetch layers from layer index

new file mode 100644
index 0000000..21d4d97
@@ -0,0 +1,154 @@
+LAYER_FETCH_DIR ??= "${COREBASE}"
+
+python layerindex_handler() {
+    import bb.event
+    if not e.data:
+        return
+
+    import httplib, urlparse, json
+    import os
+
+    def get_json_data(apiurl = "http://layers.openembedded.org/layerindex/api/"):
+        proxy_settings = os.environ.get("http_proxy", None)
+        conn = None
+        _parsedurl = urlparse.urlparse(apiurl)
+        path = _parsedurl.path
+        query = _parsedurl.query
+        def parse_url(url):
+            parsedurl = urlparse.urlparse(url)
+            try:
+                (host, port) = parsedurl.netloc.split(":")
+            except ValueError:
+                host = parsedurl.netloc
+                port = None
+
+            if port is None:
+                port = 80
+            else:
+                port = int(port)
+            return (host, port)
+
+        if proxy_settings is None:
+            host, port = parse_url(apiurl)
+            conn = httplib.HTTPConnection(host, port)
+            conn.request("GET", path + "?" + query)
+        else:
+            host, port = parse_url(proxy_settings)
+            conn = httplib.HTTPConnection(host, port)
+            conn.request("GET", apiurl)
+
+        r = conn.getresponse()
+        if r.status != 200:
+            bb.fatal("Failed to read " + path + ": %d %s" % (r.status, r.reason))
+        return json.loads(r.read())
+
+    def get_deps_url(name, layeritems, layerbranches, layerdependencies):
+        def layeritems_info(items_name = None, items_id = None):
+            litems = {}
+            for li in layeritems:
+                if li['name'] == items_name:
+                    litems['id'] = li['id']
+                    break
+                if li['id'] == items_id:
+                    litems['vcs_url'] = li['vcs_url']
+                    litems['name'] = li['name']
+                    break
+            return litems
+
+        def layerbranches_info(items_id):
+            lbranch = {}
+            for lb in layerbranches:
+                # branch is master.
+                if lb['layer'] == items_id and lb['branch'] == 1:
+                    lbranch['id'] = lb['id']
+                    lbranch['vcs_subdir'] = lb['vcs_subdir']
+                    break
+            if not lbranch['id']:
+                bb.fatal("The id of layerBranches is not found.")
+            return lbranch
+
+        def layerdependencies_info(lb_id):
+            ld_deps = []
+            for ld in layerdependencies:
+                if ld['layerbranch'] == lb_id and not ld['dependency'] in ld_deps:
+                    ld_deps.append(ld['dependency'])
+            if not ld_deps:
+                bb.fatal("The dependency of layerDependencies is not found.")
+            return ld_deps
+
+        itemsid = layeritems_info(items_name = name)['id']
+        lbid = layerbranches_info(itemsid)['id']
+        layerdict = {}
+        for dependency in layerdependencies_info(lbid):
+            layername = layeritems_info(items_id = dependency)['name']
+            layerurl = layeritems_info(items_id = dependency)['vcs_url']
+            layersubdir = layerbranches_info(dependency)['vcs_subdir']
+            layerdict[layername] = layerurl, layersubdir
+        return layerdict
+
+    import sys
+    import subprocess
+
+    def download_layer(url, subdir):
+        fetchdir = e.data.getVar("LAYER_FETCH_DIR", True)
+        if not fetchdir:
+            bb.fatal("Please set LAYER_FETCH_DIR variable.")
+        if not os.path.exists(fetchdir):
+            os.makedirs(fetchdir)
+        urldir = url.split("/")[-1]
+        if urldir.endswith(".git"):
+            urldir = urldir.split(".")[0]
+        repodir = os.path.join(fetchdir, urldir)
+        if subdir:
+            layerdir = os.path.join(repodir, subdir)
+        else:
+            layerdir = repodir
+        if not os.path.exists(layerdir):
+            bb.warn("Fetch '%s' to '%s'" % (layer, e.data.getVar("LAYER_FETCH_DIR", True)))
+            result = subprocess.call('git clone %s %s' % (url, repodir), shell = True)
+            if result:
+                bb.fatal("Failed to download %s" % url)
+            else:
+                return layerdir
+        else:
+            return layerdir
+
+    def add_layer(name, layerdir, bblayersconf):
+        f = None
+        if not os.path.exists(bblayersconf):
+            bb.fatal("Can't find conf/bblayers.conf")
+        bblayers = e.data.getVar('BBLAYERS', True).split()
+        layer = layerdir.split("/")[-1]
+        if not layerdir in bblayers:
+            if f:
+                f.close()
+            f = open(bblayersconf, 'aw')
+            f.write("BBLAYERS += \"%s\"\n" % layerdir)
+            f.close()
+            bb.fatal("Layer '%s' depends on layer '%s', but this layer is not enabled in your configuration\nAdd '%s' to BBLAYERS. You can check conf/bblayers.conf" % (name, layer, layerdir))
+
+    def get_layer():
+        layers = []
+        bblayers = e.data.getVar('BBLAYERS', True).split()
+        for bblayer in bblayers:
+            layer = bblayer.split("/")[-1]
+            if not layer == "meta":
+                layers.append(layer)
+        return layers
+
+    apilinks = get_json_data()
+    layeritems = get_json_data(apilinks['layerItems'])
+    layerbranches = get_json_data(apilinks['layerBranches'])
+    layerdependencies = get_json_data(apilinks['layerDependencies'])
+    bblayersconf = os.path.join(e.data.getVar('TOPDIR', True), 'conf/bblayers.conf')
+    names = get_layer()
+    for name in names:
+        layerdict = get_deps_url(name, layeritems, layerbranches, layerdependencies)
+        for layer in layerdict:
+            if not layer == "openembedded-core":
+                layerdir = download_layer(layerdict[layer][0], layerdict[layer][1])
+                add_layer(name, layerdir, bblayersconf)
+}
+
+addhandler layerindex_handler
+layerindex_handler[eventmask] = "bb.event.ParseStarted"