var path = require('path');
var OKQuery = require('okquery');
var OKView = require('okview');
var OKDB = require('okdb');
var OKResource = require('okresource')
var OKTemplate = require('oktemplate');
var OKServer = require('okserver');
var OKRestEndpoint = require('okrest');

/**
 * OKCMS!
 * Basically takes configuration and gives you a server.
 */
function OKCMS(options) {
  options = options || {};
  var root = this._root = options.root || 'www';
  // Reduce resource config into unique set
  this._resourceConfig = options.resources || [];
  this._views = options.views || {
    '/': { template: 'index' }
  };
  this._resourceRoot = options.resourceRoot || '/api';
  this._server = new OKServer({root: root});
  this._templates = new OKTemplate({root: root});
  var db = this._db = options.db || new OKDB();
  // Special query for getting meta info
  this._meta = options.meta || {
    name: 'meta',
    get: function() {
      return db.getMeta();
    }
  };
  this._init();
}

OKCMS.prototype.listen = function listen(port, options) {
  options = options || {};
  this._server.listen(port);
};

OKCMS.prototype._init = function _init() {
  var self = this;

  // Create resources instances from config and add CRUD views on them
  // NOTE Does not support subresources
  this._resources = this._resourceConfig.map(function (config) {
    var resource = self._createResource(config);
    var route = path.join(self._resourceRoot, resource.name);
    self._server.addView(route, resource.view());
    return resource;
  });

  // Add HTML views
  Object.keys(this._views)
    // Make sure more specific routes are processed first
    // TODO This is not semantically correct (bro)
    .sort(function(a, b) {
      return a.length < b.length;
    })
    // For each route / viewOptions pair, add a view
    .forEach(function eachRoute(route) {
      var options = self._views[route];
      // View should know what its route is.
      options.route = route;
      var view = self._createView(options);
      // Add view at route
      self._server.addView(route, view);
    });
};

/**
 * Takes a resource configuration object and returns a resource instance
 */
OKCMS.prototype._createResource = function(options) {
  options = options || {};
  var resourceClass = options.resource;
  // No resource? Bail!
  if (!resourceClass) throw new Error('OKCMS: No resource class given');
  // Default to 'select all' id
  options.id = options.id || '*';
  // Some dependency injection
  options.db = this._db;
  // Clean unpassed options
  delete options.resource;
  // Return resource instance
  return resourceClass(options);
};

/**
 * Takes a view configuration object and returns a view instance
 */
OKCMS.prototype._createView = function _createView(options) {
  options = options || {};
  var self = this;
  var viewClass = options.view || OKView;
  var template = this._templates.getTemplate(options.template);
  var queryConfig = options.data || [];
  // No template? Bail!
  if (!template) throw new Error('OKCMS: No template "' + options.template + '"');
  // Inject them dependencies
  options.template = template;
  options.meta = this._meta;
  options.queries = this._createQueries(queryConfig);
  // Clean options not passed to view
  delete options.view;
  // Return view instance
  return viewClass(options);
};

/**
 * Takes a query configuration and returns a list of queries
 */
OKCMS.prototype._createQueries = function(options) {
  options = options || [];
  var db = this._db;
  if (!options.length)
    options = [options];
  return options.map(function(option) {
    if (!option.name)
      throw new Error('No document name provided to query');
    option.id = option.id || '*';
    return new OKQuery(db, {
      name: option.name,
      id: option.id
    });
  });
};

module.exports = {

  createApp: function(options) {
    return new OKCMS(options);
  },

  OKResource: OKResource,

  OKView: OKView,

  OKRestEndpoint: OKRestEndpoint

};