/*global define*/

define(
    [],
    function () {
        'use strict';

        function CouchPersistenceProvider($http, $q, SPACE, PATH) {
            var spaces = [ SPACE ],
                revs = {};

            function url(subpath) {
                return PATH + '/' + subpath;
            }

            function request(subpath, method, value) {
                return $http({
                    method: method,
                    url: url(subpath),
                    data: value
                }).then(function (response) {
                    return response.data;
                }, function () {
                    return undefined;
                });
            }

            function get(subpath) { return request(subpath, "GET"); }
            function put(subpath, value) { return request(subpath, "PUT", value); }
            function del(subpath, value) { return request(subpath, "DELETE", value); }

            function getIdsFromAllDocs(allDocs) {
                return allDocs.rows.map(function (r) { return r.id; });
            }

            /*jslint nomen: true */ // Allow the _id and _rev that couch provides
            function getModel(response) {
                if (response && response.model) {
                    revs[response._id] = response._rev;
                    return response.model;
                } else {
                    return undefined;
                }
            }

            function checkResponse(response) {
                if (response && response.ok) {
                    revs[response.id] = response.rev;
                    return response.ok;
                } else {
                    return undefined;
                }
            }

            function CouchDocument(key, value, includeRevision, markDeleted) {
                return {
                    "_id": key,
                    "_rev": includeRevision ? revs[key] : undefined,
                    "_deleted": markDeleted,
                    "metadata": {
                        "category": "domain object",
                        "type": value.type,
                        "owner": "admin",
                        "name": value.name,
                        "created": Date.now()
                    },
                    "model": value
                };
            }

            return {
                listSpaces: function () {
                    return $q.when(spaces);
                },
                listObjects: function (space) {
                    return get("_all_docs").then(getIdsFromAllDocs);
                },
                createObject: function (space, key, value) {
                    return put(key, new CouchDocument(key, value))
                        .then(checkResponse);
                },
                readObject: function (space, key) {
                    return get(key).then(getModel);
                },
                updateObject: function (space, key, value) {
                    return put(key, new CouchDocument(key, value, true))
                        .then(checkResponse);
                },
                deleteObject: function (space, key, value) {
                    return put(key, new CouchDocument(key, value, true, true))
                        .then(checkResponse);
                }
            };

        }

        return CouchPersistenceProvider;
    }
);