var express = require("express")
  , passport = require("passport")
  , passportLocal = require("passport-local")
  , fs = require("fs")
  , path = require("path")
  , proxy = require("./util/simple-http-proxy")
  , CouchDB = require('./util/couch')
  , HTTPResult = require('./util/http-result')
  , _ = require("underscore")
  ;

exports.app = function(env) {

    assertSetting("couchServerURL", env, _.isString);
    assertSetting("dbName", env, _.isString);
    assertSetting("mode", env, _.isString);
    var couch = new CouchDB(env.couchServerURL,env.dbName);
    
    var schema = require("./config/couchdb-schema.json");
    var views = require("./config/couchdb-design-docs.js");
    return couch.get("schemaInfo")
    .then(function(schemaInfo){
        if ( schemaInfo.version !== schema.version ) {
            return HTTPResult.fail(
                new Error("Found schema version "+schemaInfo.version+
                          ", expected "+schema.version));
        } else if ( schemaInfo.viewsVersion !== views.schemaInfo.viewsVersion ) {
            return HTTPResult.fail(
                new Error("Found views version "+schemaInfo.viewsVersion+
                          ", expected "+views.schemaInfo.viewsVersion));
        } else {
            return configureApp(env,couch,schema);
        }
    });

};

function configureApp(env,couch,schema) {

    var apiUtil = require('./api/util')(couch,schema);

    function clientPath(relativePath) {
        return path.resolve(__dirname+'/../client/'+relativePath);
    }

    passport.use(
        new passportLocal.Strategy(
            function(username, password, done){
                if ( username === "igor" && password === "mayer" ) {
                    done(null,{ username: "igor" });
                } else {
                    done(null,false,{ message: 'Invalid credentials.' });
                }
            }));
    passport.serializeUser(function(user, done) {
        done(null, user.username);
    });
    passport.deserializeUser(function(id, done) {
        done(null, {username: id});
    });

    var app = express();
    app.use(express.logger());
    app.use(express.compress());
    app.use(express.favicon());

    // cookies and session
    app.use(express.cookieParser());
    app.use(express.session({ secret: "quasi experimental design" }));
    app.use('/api',express.bodyParser());

    // passport
    app.use(passport.initialize());
    app.use(passport.session());
    
    // various middlewares
    function ensureAuthenticated(req,res,next){
        if (!req.user) {
            return res.send(401,{error:"Login before accessing API."});
        } else {
            return next();
        }
    }
    function returnUser(req,res) {
        res.send(200, req.user);
    }
    function notImplemented(req,res) {
        res.send(501,{error:"API not implemented yet."});
    }

    // static resources
    app.get('/', function(req, res){
        res.sendfile(clientPath('index.html'));
    });
    app.get('/*.html', function(req, res) {
        res.sendfile(clientPath(req.path));
    });
    _.each(['/dojo', '/dijit', '/dojox', '/qed', '/qed-client'], function(dir){
        app.use(dir, express.static(clientPath(dir)));
    });

    // post to this url to login
    app.post(
        '/api/login',
        passport.authenticate('local'),
        returnUser);

    // return the info for the current logged in user
    app.get(
        '/api/login',
        ensureAuthenticated,
        returnUser);

    // explicitly logout this user
    app.post(
        '/api/logout',
        ensureAuthenticated,
        function(req,res){
            req.logout();
            res.send(200,{});
        });

    app.use('/api/questions', ensureAuthenticated);
    app.use('/api/questions',
            require('./api/questions')(couch,schema).app);

    app.use('/api/categories', ensureAuthenticated);
    app.use('/api/categories',
            require('./api/categories')(couch,schema).app);

    app.use('/api/topics', ensureAuthenticated);
    app.use('/api/topics',
            require('./api/topics')(couch,schema).app);

    app.use('/api/surveys', ensureAuthenticated);
    app.use('/api/surveys',
            require('./api/surveys')(couch,schema).app);

    app.use('/api/surveyRuns', ensureAuthenticated);
    app.use('/api/surveyRuns',
            require('./api/surveyRuns')(couch,schema).app);

    app.use('/api/responses', ensureAuthenticated);
    app.use('/api/responses',
            require('./api/responses')(couch,schema).app);

    app.use('/api/open',
            require('./api/open')(couch,schema).app);

    app.get('/api/mode',
        apiUtil.ensureMIME(apiUtil.JSON_MIME),
        function(req,res){
            res.send({mode:env.mode});
        });


    return app;
}

function assertSetting(name, settings, validate) {
    if ( typeof settings[name] === 'undefined' ) {
        throw new Error("Required setting '"+name+"' undefined.");
    }
    if ( _.isFunction(validate) && !validate(settings[name]) ) {
        throw new Error("Setting '"+name+"' with value '"+settings[name]+"' is invalid.");
    }
}