var path = require('path');
var format = require('util').format;
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');
var OKSchema = require('okschema');

/**
 * OKCMS!
 * Basically takes configuration and gives you a server.
 */
function OKCMS(options) {
  if (!(this instanceof OKCMS)) return new OKCMS(options);
  options = options || {};
  var root = this._root = options.root || 'www';
  var schemaConfig = options.schemas || {};
  var resourceConfig = options.resources || [];
  var viewConfig = options.views || {
    '/': { template: 'index' }
  };
  var db = new OKDB(options.db || 'fs');
  var templateCache = this._templateCache = new OKTemplate({root: root});
  var server = this._server = new OKServer({root: root});
  var meta = this._meta = {
    name: 'meta',
    get: function() {
      return db.getMeta();
    }
  };
  var schemas = this._schemas = this._createSchemas(schemaConfig);
  var resources = this._resources =
      this._createResources(resourceConfig, db, schemas);
  var views = this._views =
      this._createViews(viewConfig, db, meta, resources, templateCache);
  this._initViews(server, views);
}

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

OKCMS.prototype._createSchemas = function(schemaConfig) {
  schemaConfig = schemaConfig || {};
  return Object.keys(schemaConfig).reduce(function(cache, key) {
    var spec = schemaConfig[key];
    cache[key] = OKSchema(spec);
    return cache;
  }, {});
}

OKCMS.prototype._createResources = function(resourceConfig, db, schemaCache) {
  resourceConfig = resourceConfig || {};
  var typeCache = {};
  return resourceConfig.reduce(function(cache, config) {
    var type = config.type;
    var schema = schemaCache[type];
    if (!schema)
      throw new Error('Resource config references nonexistent schema');
    // If we already created resource class, just skip
    if (cache[type])
      return cache;
    cache[type] = OKResource({
      type: type,
      db: db,
      schema: schema
    })
    return cache;
  }, {});
};

OKCMS.prototype._createViews = function(viewConfig, db,
    meta, resourceCache, templateCache) {
  viewConfig = viewConfig || {};
  var self = this;
  var createQueries = this._createQueries.bind(this);
  return Object.keys(viewConfig).reduce(function(cache, route) {
    var config = viewConfig[route];
    var templateName = config.template || getDefaultTemplate(route, config);
    var template = templateCache.getTemplate(templateName);
    if (!template)
      throw new Error(format('No template named "%s" found', templateName));
    var queryConfig = config.data || [];
    var queries = createQueries(queryConfig, resourceCache);
    // Instantiate!
    cache[route] = OKView({
      route: route,
      template: template,
      queries: queries,
      meta: meta
    });
    return cache;
  }, {});

  /**
   * Returns the default template for a view config
   */
  function getDefaultTemplate(route, config) {
    // Root route defaults to index
    if (/^\/?$/.test(route))
      return 'index';
    // Otherwise default to the backing resource name
    else if (config && config.data && config.data.type)
      return config.data.type;
    // Otherwise dunno
    else
      return '404';
  }
}

OKCMS.prototype._createQueries = function(queryConfig, resourceCache) {
  queryConfig = queryConfig || {};
  if (!queryConfig.length)
    queryConfig = [queryConfig];
  return queryConfig.map(function(config) {
    var type = config.type;
    var resource = resourceCache[type];
    if (!resource)
      throw new Error('Query configured with nonexistent resource');
    // Default to "select all" query
    var query = config.query || '*';
    return new OKQuery({
      resource: resource,
      query: query
    });
  });
};

OKCMS.prototype._initViews = function(server, views) {
  Object.keys(views)
      // Make sure more specific routes are processed first
      // TODO This is not semantically correct (bro)
      //      Will prob manifest bugs
      .sort(function(a, b) {
        return a.length < b.length;
      })
      // Add the views
      .forEach(function(route) {
        server.addView(route, views[route]);
      });
};

module.exports = {

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

  OKResource: OKResource,

  OKView: OKView,

  OKRestEndpoint: OKRestEndpoint

};