draft of CouchDB adaptor for TiddlyWiki

gistfile1.txt

/*\
title: $:/plugins/tiddlywiki/tiddlyweb/tiddlywebadaptor.js
type: application/javascript
module-type: syncadaptor

A sync adaptor module for synchronising with Couch compatible servers 

\*/
(function () {

    /*jslint node: true, browser: true */
    /*global $tw: false */
    "use strict";


    function CouchDBAdaptor(syncer) {
        this.syncer = syncer;
        this.host = this.getHost();
        this.recipe = undefined;
        this.logger = new $tw.utils.Logger("CouchDBAdaptor");
    }

    CouchDBAdaptor.prototype.getHost = function () { }


    CouchDBAdaptor.prototype.getTiddlerInfo = function (tiddler) {
        return {
            bag: tiddler.fields["bag"]
        };
    };

    /*
    Get the current status of the TiddlyWeb connection
    */
    CouchDBAdaptor.prototype.getStatus = function (callback) {
//        debugger;
        console.log('getStatus');
        var self = this;
        if (callback) {
            callback(null, false, null);
        }
    };

    /*
    Provide the array of skinny tiddler that the syncer is looking for
    */
    CouchDBAdaptor.prototype.getSkinnyTiddlers = function (callback) {
//        debugger;
        var self = this;
        couchdb.get("SkinnyTiddlers", function (err, doc) {
            self.logger.log('got Skinny Tiddlers: ')
            self.logger.log(doc);
            callback(null, doc.tiddlers);
        });
    };

    /*
    Save a tiddler and invoke the callback with (err,adaptorInfo,revision)
    */
    CouchDBAdaptor.prototype.saveTiddler = function (tiddler, callback) {

//        debugger;
        var title_to_save = tiddler.fields.title;
        this.logger.log('saving ' + title_to_save);
        var self = this;

        var changeCount = this.syncer.wiki.getChangeCount(title_to_save).toString();

        couchdb.get("SkinnyTiddlers", function (err, doc) {

            var skinnies = [];
            var found = false;

            self.syncer.wiki.forEachTiddler({ sortField: "title" }, function (title, tiddler) {
                var tiddlerFields = {};
                $tw.utils.each(tiddler.fields, function (field, name) {
                    //                        if (name !== "text")  {
                    if (name !== "text") {
                        tiddlerFields[name] = tiddler.fields[name];
                    }
                });
                tiddlerFields["revision"] = self.syncer.wiki.getChangeCount(title);
                tiddlerFields.type = tiddlerFields.type || "text/vnd.tiddlywiki";
                skinnies.push(tiddlerFields);
            });

            var new_doc = {
                _id: "SkinnyTiddlers",
                _rev: doc._rev,
                tiddlers: skinnies
            }

            couchdb.put(new_doc, function (err, resp) {
                console.log(err);
                console.log(resp);
            });

        });

        couchdb.get(title_to_save, function (err, doc) {
            if (err == null) {
                couchdb.put(tiddler.fields, title_to_save, doc._rev, {}, function (err, response) { console.log(err); console.log(response); });

            }
            else {
                if (err.status == 404) {
                    couchdb.put(tiddler.fields, title_to_save, null, {}, function (err, response) { console.log(err); console.log(response); });
                }
                else {
                    console.log(err);
                }
            }

        });

        var enqueue_load = false;

        //       if (!tiddler.fields['draft.of']) {
        if (enqueue_load) {
            console.log('queueing load for ' + title_to_save);
            self.syncer.enqueueSyncTask({
                type: "load",
                title: title_to_save
            });
        }

        var ETag = '"' + encodeURIComponent(title_to_save) + "/" + changeCount + ":" + '"';
        var etagInfo = self.parseEtag(ETag);

        callback(null, {
            bag: etagInfo.bag
        }, etagInfo.revision);

    };



    /*
    Load a tiddler and invoke the callback with (err,tiddlerFields)
    */
    CouchDBAdaptor.prototype.loadTiddler = function (title, callback) {
        console.log('loading ' + title);
//        debugger;
        var self = this;

        couchdb.get(title, function (err, doc) {
            console.log(err);
            console.log('loaded ' + doc);
            delete doc._id;
            delete doc._rev;
            if (doc['modified'])
                doc['modified'] = new Date(doc['modified']);
            if (doc['created'])
                doc['created'] = new Date(doc['created']);
            callback(null, doc);

        });

    };

    /*
    Delete a tiddler and invoke the callback with (err)
    */
    CouchDBAdaptor.prototype.deleteTiddler = function (title, callback) {
        console.log('deleting ' + title);
//        debugger;
        var self = this,
            bag = this.syncer.tiddlerInfo[title].adaptorInfo.bag;
        // If we don't have a bag it means that the tiddler hasn't been seen by the server, so we don't need to delete it
        if (!bag) {
            return callback(null);
        }

        couchdb.get(title, function (err, doc) {
            couchdb.remove(doc, function (err, doc) {
            });
        });

        callback(null);

    };

    /*
    Split a TiddlyWeb Etag into its constituent parts. For example:
    
    ```
    "system-images_public/unsyncedIcon/946151:9f11c278ccde3a3149f339f4a1db80dd4369fc04"
    ```
    
    Note that the value includes the opening and closing double quotes.
    
    The parts are:
    
    ```
    <bag>/<title>/<revision>:<hash>
    ```
    */
    CouchDBAdaptor.prototype.parseEtag = function (etag) {
        var firstSlash = etag.indexOf("/"),
            lastSlash = etag.lastIndexOf("/"),
            colon = etag.lastIndexOf(":");
        if (firstSlash === -1 || lastSlash === -1 || colon === -1) {
            return null;
        } else {
            return {
                bag: decodeURIComponent(etag.substring(1, firstSlash)),
                title: decodeURIComponent(etag.substring(firstSlash + 1, lastSlash)),
                revision: etag.substring(lastSlash + 1, colon)
            };
        }
    };

    if ($tw.browser) {
        exports.adaptorClass = CouchDBAdaptor;
    }

})();