module.exports = function(io) {

    var pty = require('pty.js');
    var proc = require('child_process');

    var module={};
    var idtoname = {};
    
    function broadcast(signal, data) {
        console.log("<= signal: "+signal);
        io.sockets.emit(signal, data);
    }
    
    function exec(cmd, callback) {
        console.log("== "+cmd);
        proc.exec(cmd, callback);
    }

    var oldcontainer = null;
    function containerinspect(error, stdout, stderr) {
        if (error || stderr)
            return fail("inspect docker containers failed", {
                error: error, stderr: stderr, stdout: stdout
            });
        JSON.parse(stdout).forEach(function(n) {
            idtoname[n.Id] = n.Name.replace(/^\//, '');;
        });
        if (oldcontainer && oldcontainer==stdout) return; // do not resend same containers
        oldcontainer = stdout;
        broadcast("containers", stdout);
    }
    
    function containerlist(error, stdout, stderr) {
        if (error || stderr)
            return fail("list docker containers failed", {
                error: error, stderr: stderr, stdout: stdout
            });
        exec("docker inspect "+stdout.trim().replace(/\n/g, " "), containerinspect);
    }

    function updatecontainers(error, stdout, stderr) {
        if (error || stderr)
            return fail("update docker container failed", {
                error: error, stderr: stderr, stdout: stdout
            });
        exec("docker ps -aq --no-trunc ", containerlist);
    }

    var oldimage = null;
    function imageinspect(error, stdout, stderr) {
        if (error || stderr)
            return fail("inspect docker images failed", {
                error: error, stderr: stderr, stdout: stdout
            });
        if (oldimage && oldimage==stdout) return; // do not resend same images
        oldimage = stdout;
        broadcast("images", stdout);
    }
    
    function imagelist(error, stdout, stderr) {
        if (error || stderr)
            return fail("list docker images failed", {
                error: error, stderr: stderr, stdout: stdout
            });
        exec("docker inspect "+stdout.trim().replace(/\n/g, " "), imageinspect);
    }

    function updateimages(error, stdout, stderr) {
        if (error || stderr)
            return fail("update docker images failed", {
                error: error, stderr: stderr, stdout: stdout
            });
        exec("docker images -q --no-trunc", imagelist);
    }

    function connection(socket) {

        console.log("new client");

        function emit(signal, data, info) {
            if (typeof data == 'string' && !data.match("\n")) {
                console.log("<- signal: "+signal+"("+data+")");
            } else {
                console.log("<- signal: "+signal);
            }
            if (info) console.log(info);
            socket.emit(signal, data);
        }

        function fail(txt, data) {
            console.log("** "+txt, data);
            emit("fail", txt);
        }

        function modify(cmd, name) {
            if (!name.match(/^[a-z0-9][-_:.+a-z0-9]*$/i))
                return fail("illegal instance name");
            exec("docker "+cmd+" "+name, updatecontainers);
        }

        function modify(cmd, name) {
            if (!name.match(/^[a-z0-9][-_:.+a-z0-9]*$/i))
                return fail("illegal instance name");
            exec("docker "+cmd+" "+name, updatecontainers);
        }

        function containers() {
            console.log("-> containers");
            if (oldcontainer) emit("containers", oldcontainer);
            else updatecontainers();
        }
        
        function images() {
            console.log("-> images");
            if (oldimage) emit("images", oldimage);
            else updateimages();
        }
    
        function start(name) {
            console.log("-> start("+name+")");
            modify("start", name);
        }

        function stop(name) {
            console.log("-> stop("+name+")");
            modify("stop", name);
        }

        function pause(name) {
            console.log("-> pause("+name+")");
            modify("pause", name);
        }

        function unpause(name) {
            console.log("-> unpause("+name+")");
            modify("unpause", name);
        }

        function remove(name) {
            console.log("-> remove("+name+")");
            modify("rm", name);
        }

        function logs(name) {
            console.log("-> logs("+name+")");
            var l = proc.spawn("docker", ["logs", "-f", name])
                .on('close', function(code) {
                    emit('logs', {name: name, type: 'done'});
                });
            l.stdout.on('data', function(data) {
                emit('logs', {name: name, type: 'stdout', text: data.toString()});
            });
            l.stderr.on('data', function(data) {
                emit('logs', {name: name, type: 'stderr', text: data.toString()});
            });
        }

        var bash_connections = {};

        function new_bash(name) {
            if (!name.match(/^[a-z0-9][-_:.+a-z0-9]*$/i))
                return fail("illegal instance name");
            if (bash_connections[name]) return;
            bash_connections[name] =
                pty.spawn("docker", ["exec", "-it", name, "bash", "-i"]);
            bash_connections[name].stdout.on('data', function(data) {
                emit('bash-data', {name: name, type: 'stdout', text: data.toString()});
            });
        }

        function bash_start(name) {
            console.log("-> bash-start("+name+")");
            new_bash(name);
        }
        
        function bash_input(data) {
            console.log("-> bash-input("+data.name+", "+data.text+")");
            new_bash(data.name);
            bash_connections[data.name].stdin.resume();
            bash_connections[data.name].stdin.write(data.text);
        }

        function bash_end(name, text) {
            console.log("-> bash-end("+name+")");
            if (!bash_connections[name]) return;
            bash_connections[name].stdin.close();
            delete bash_connections[name]; bash_connections[name] = null;
        }

        socket
            .on("containers", containers)
            .on("images", images)
            .on("start", start)
            .on("stop", stop)
            .on("pause", pause)
            .on("unpause", unpause)
            .on("remove", remove)
            .on('logs', logs)
            .on('bash-start', bash_start)
            .on('bash-input', bash_input)
            .on('bash-end', bash_end);

    }
    
    function stats() {
        var res = {};
        var fs = require('fs');
        var async = require('async');
        var base = "/sys/fs/cgroup/";
        var dataPoints = {
            "cpuacct": [
                "usage"
            ],
            "memory": [
                "usage_in_bytes",
                "limit_in_bytes",
                "max_usage_in_bytes"
            ]
        };
        async.forEachOf(idtoname, function(name, id, cb1) {
            res[name] = {};
            async.forEachOf(dataPoints, function(val1, category, cb2) {
                res[name][category] = {};
                async.each(val1, function(element, cb3) {
                    var file = base + category + '/docker/' + id + '/' + category + '.' + element;
                    fs.readFile(file, 'utf8', function(err, data) {
                        res[name][category][element] = {
                            date: (new Date()).getTime(),
                            data: {}
                        };
                        if (err) {cb3(); console.log(err); return}
                        data.trim().split('\n').forEach(function(v, i) {
                            var vals = v.split(' ');
                            switch (vals.length) {
                            case 1:
                                res[name][category][element].data = parseInt(vals[0]);
                                break;
                            case 2:
                                res[name][category][element].data[vals[0]] = parseInt(vals[1]);
                                break;
                            }
                        });
                        cb3();
                    });
                }, function(err) {
                    cb2();
                });
            }, function(err) {
                cb1();
            });
        }, function(err) {
            if (err) return;
            broadcast("stats", res);
        });
    }
    
    // Handle Connection
    io.sockets.on('connection', connection);

    // Regular Update of Stats
    setInterval(function() {
        stats();
    }, 1000);
            
    // Regular Update of Images and Containers
    setInterval(function() {
        updateimages();
        updatecontainers();
    }, 10000);
            
    return module;
}