var express = require("express")
  , HTTPResult = require("../util/http-result")
  , _ = require("underscore")
  , objF = require("../util/object")
  , etags = require("../util/etags")
  ;

module.exports = function(couch,schema) {
    var util = require('./util')(couch,schema);
    var exports = {};

    var app = exports.app = express();

    var getQuestionsWithCode = exports.getQuestionsWithCode = function(code,sub) {
        var url = '_design/questions/_view/'+(sub||'all')+'_by_code';
        var query = {reduce:false,include_docs:true,key:code};
        return couch.get(url,{query:query})
        .handle({
            200: util.handleRowDocs,
            default: util.handleUnknownResponse
        });
    };
    var getQuestions = exports.getQuestions = function(sub) {
        var url = '_design/questions/_view/'+(sub||'all');
        var query = {reduce:false,include_docs:true};
        return couch.get(url,{query:query})
        .handle({
            200: util.handleRowDocs,
            default: util.handleUnknownResponse
        });
    };
    var getQuestionsAndCodes = exports.getQuestionsAndCodes = function(sub) {
        var url = '_design/questions/_view/'+(sub||'all')+'_by_code';
        var query = {};
        return couch.get(url,{query:query})
        .handle({
            200: util.handleRowDictOfValues,
            default: util.handleUnknownResponse
        });
    };
    var getQuestionsWithTopic = exports.getQuestionsWithTopic = function(topic,sub) {
        var url = '_design/questions/_view/'+(sub||'all')+'_topics';
        var query = {reduce:false,include_docs:true,key:topic};
        return couch.get(url,{query:query})
        .handle({
            200: util.handleRowDocs,
            default: util.handleUnknownResponse
        });
    };
    var getQuestionsWithCategoryAndTopic = exports.getQuestionsWithCategoryAndTopic = function(category,topic,sub) {
        var hasTopic = typeof topic !== 'undefined';
        var url = '_design/questions/_view/'+(sub||'all');
        var query = {reduce:false,include_docs:true,
                     startkey:hasTopic?[category,topic]:[category],
                     endkey:hasTopic?[category,topic]:[category,{}]};
        return couch.get(url,{query:query})
        .handle({
            200: util.handleRowDocs,
            default: util.handleUnknownResponse
        });
    };
    var areElementsUnique = exports.areElementsUnique = function(array) {
        return _.uniq(array).length === array.length;
    };
    var getVariablesAndIds = exports.getVariablesAndIds = function(sub) {
        var url = '_design/questions/_view/'+(sub||'all')+'_variables';
        return couch.get(url)
        .handle({
            200: util.handleRowDictOfValues,
            default: util.handleUnknownResponse
        });
    };
    var collectVariables = exports.collectVariables = function(question) {
        return _.chain(objF.collectFields('subcode',question.content))
        .map(function(subcode){
            return question.code+subcode;
        }).value();
    };

    app.get('/',
        util.ensureMIME(util.JSON_MIME),
        function(req,res) {
            var sub = 'published' in req.query && 'published';
            var hr;
            if ( 'category' in req.query ) {
                hr = getQuestionsWithCategoryAndTopic(req.query.category,
                                                      req.query.topic,sub);
            } else if ( 'topic' in req.query ) {
                hr = getQuestionsWithTopic(req.query.topic,sub);
            } else if ( 'code' in req.query ) {
                hr = getQuestionsWithCode(req.query.code,sub);
            } else {
                hr = getQuestions(sub);
            }
            hr.handle(res.send.bind(res));
        });
    app.post('/',
        util.ensureMIME(util.JSON_MIME),
        function (req,res) {
            var doc = req.body;
            var ourVars = collectVariables(doc);
            var hr;
            var dups = objF.findDuplicates(ourVars);
            if ( dups.length > 0 ) {
                hr = new HTTPResult(400,{error:"Question defines variable(s) "+
                                               dups.join(',')+
                                               " multiple times (subcodes not unique)."});
            } else {
                hr = getVariablesAndIds()
                .handle({
                    200: function(vars) {
                        vars = _.chain(vars).keys().uniq().value(); // don't punish us for others mistakes
                        dups = objF.findDuplicates(vars.concat(ourVars));
                        if ( dups.length > 0 ) {
                            return new HTTPResult(400,{error:"Question redefines variable(s) "+
                                                             dups.join(',')+
                                                             " (already defined in other question(s))."});
                        } else {
                            return util.postDocument('Question',doc);
                        }
                    }
                });
            }
            hr.handle(res.send.bind(res));
        });
    app.get('/:id',
        util.ensureMIME(util.JSON_MIME),
        util.makeDocGet_id('Question'));
    app.put('/:id',
        util.ensureMIME(util.JSON_MIME),
        function (req,res) {
            var id = req.params.id;
            var doc = req.body;
            var rev = etags.parse(req.header('If-Match'))[0] || (doc && doc._rev);
            var ourVars = collectVariables(doc);
            var hr;
            var dups = objF.findDuplicates(ourVars);
            if ( dups.length > 0 ) {
                hr = new HTTPResult(400,{error:"Question defines variable(s) "+
                                               dups.join(',')+
                                               " multiple times (subcodes not unique)."});
            } else {
                hr = getVariablesAndIds()
                .handle({
                    200: function(vars) {
                        vars = _.chain(vars).map(function(otherId,otherVar){
                            return otherId !== id ? otherVar : null;
                        }).filter(function(otherCode){
                            return otherCode !== null;
                        }).uniq().value(); // don't punish us for others mistakes
                        dups = objF.findDuplicates(vars.concat(ourVars));
                        if ( dups.length > 0 ) {
                            return new HTTPResult(400,{error:"Question redefines variable(s) "+
                                                             dups.join(',')+
                                                             " (already defined in other question(s))."});
                        } else {
                            return util.putDocument(id,rev,'Question',doc);
                        }
                    }
                });
            }
            hr.handle(res.send.bind(res));
        });
    app.delete('/:id',
        util.ensureMIME(util.JSON_MIME),
        util.makeDocDel_id('Question'));

    return exports;
};