/*
 * Copyright (C) 2019 "IoT.bzh"
 * Author Sebastien Douheret <sebastien@iot.bzh>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package agent

import (
	"fmt"
	"io"
	"strings"
	"time"

	"gerrit.automotivelinux.org/gerrit/src/xds/xds-agent.git/lib/aglafb"
	common "gerrit.automotivelinux.org/gerrit/src/xds/xds-common.git"
	uuid "github.com/satori/go.uuid"
)

// XdsLowCollector .
type XdsLowCollector struct {
	*Context
	ID                 string
	BaseURL            string
	ConnRetry          int
	Connected          bool
	Disabled           bool
	DefaultPlugins     []string
	DefaultCollectTime int
	// Private fields
	client      *common.HTTPClient
	logOut      io.Writer
	cbOnConnect OnConnectedXdsAlcCB
}

// OnConnectedXdsAlcCB connect callback
type OnConnectedXdsAlcCB func(svr *XdsLowCollector) error

// NewXdsLowCollector creates an instance of XdsLowCollector
func NewXdsLowCollector(ctx *Context) *XdsLowCollector {
	return &XdsLowCollector{
		Context:   ctx,
		ID:        "XdsAlc-" + uuid.NewV1().String(),
		BaseURL:   ctx.Config.FileConf.ProfileConf.XDSLowCollector.URL,
		ConnRetry: ctx.Config.FileConf.ProfileConf.XDSLowCollector.ConnRetry,
		Connected: false,
		Disabled:  false,
		logOut:    ctx.Log.Out,
		DefaultPlugins: []string{
			"cpu",
			"memory",
			// SEB "processes",
			//"cpufreq",
			//"thermal",
			//"systemd_journal",
			// SEB "systemd_file",
		},
		DefaultCollectTime: 5,
	}
}

// Connect Establish HTTP connection with XDS Low Collector Dameon
func (xs *XdsLowCollector) Connect() error {
	var err error
	var retry int

	xs.Disabled = false
	xs.Connected = false

	err = nil
	for retry = xs.ConnRetry; retry > 0; retry-- {
		if err = xs._CreateConnectHTTP(); err == nil {
			break
		}
		if retry == xs.ConnRetry {
			// Notify only on the first conn error
			// doing that avoid 2 notifs (conn false; conn true) on startup
			xs._NotifyState()
		}
		xs.Log.Infof("Establishing connection to XDS Low Collector daemon (retry %d/%d)", retry, xs.ConnRetry)
		time.Sleep(time.Second)
	}
	if retry == 0 {
		// FIXME: re-use _Reconnect to wait longer in background
		return fmt.Errorf("Connection to XDS Low Collector daemon failure")
	}
	if err != nil {
		return err
	}

	// Check HTTP connection and establish WS connection
	err = xs._Connect(false)

	return err
}

// ConnectOn Register a callback on events reception
func (xs *XdsLowCollector) ConnectOn(f OnConnectedXdsAlcCB) error {
	xs.cbOnConnect = f
	return nil
}

// GetVersion Send Get request to retrieve XDS Low Collector version
func (xs *XdsLowCollector) GetVersion(res interface{}) error {
	// FIXME add suffix URLSuffix in common HTTP client lib instead of _BuildURL
	return xs.client.Get(xs._BuildURL("/version"), &res)
}

// Init Initialize collector plugins
func (xs *XdsLowCollector) Init() error {
	var err error

	// Directly send config in order to init and config plugins

	type alcCfgPluginT struct {
		Plugin string `json:"plugin"`
		Config string `json:"config"`
	}

	cfg := []alcCfgPluginT{}

	for _, p := range xs.DefaultPlugins {
		cfg = append(cfg, alcCfgPluginT{
			Plugin: p,
			Config: "default",
		})
	}

	res := aglafb.NewAfbReply()
	xs.Log.Debugf("Low Collector /config %v", cfg)
	err = xs.client.Post(xs._BuildURL("/config"), cfg, res)

	if err == nil && !res.Success() {
		err = res.GetError()
	}

	return err
}

// Start data collection
func (xs *XdsLowCollector) Start(time int) error {
	var err error

	// TODO - SEB : support start one or multiple plugins

	if time == 0 {
		time = xs.DefaultCollectTime
	}

	type alcStartT struct {
		Plugin string `json:"plugin"`
		Time   int    `json:"time"`
	}

	// TODO SEB : allow to start only 1 plugin
	allInOne := true
	if allInOne {

		cfg := []alcStartT{}
		for _, p := range xs.DefaultPlugins {
			cfg = append(cfg, alcStartT{Plugin: p, Time: time})
		}

		res := aglafb.NewAfbReply()
		xs.Log.Debugf("Low Collector /start %v", cfg)
		err = xs.client.Post(xs._BuildURL("/start"), cfg, res)

		if err == nil && !res.Success() {
			err = res.GetError()
		}
	} else {
		for _, p := range xs.DefaultPlugins {
			cfg := alcStartT{Plugin: p, Time: time}

			res := aglafb.NewAfbReply()
			xs.Log.Debugf("Low Collector /start %v", cfg)
			err = xs.client.Post(xs._BuildURL("/start"), cfg, res)
			if err != nil {
				return err
			}
			if !res.Success() {
				return res.GetError()
			}
		}
	}

	return err
}

// Stop data collection
func (xs *XdsLowCollector) Stop() error {

	// TODO - SEB : support start one or multiple plugins

	type alcStopT struct {
		Plugin []string `json:"plugin"`
	}

	cfg := alcStopT{}
	for _, p := range xs.DefaultPlugins {
		cfg.Plugin = append(cfg.Plugin, p)
	}

	res := aglafb.NewAfbReply()
	xs.Log.Debugf("Low Collector /stop %v", cfg)
	err := xs.client.Post(xs._BuildURL("/stop"), cfg, res)

	if err == nil && !res.Success() {
		err = res.GetError()
	}

	return err
}

// Read a single data of a specific plugin
func (xs *XdsLowCollector) Read(data interface{}) error {
	return fmt.Errorf("No implemented")
}

/***
** Private functions
***/

// _BuildURL .
func (xs *XdsLowCollector) _BuildURL(url string) string {
	return url + "?token=HELLO&uuid=magic"
}

// Create HTTP client
func (xs *XdsLowCollector) _CreateConnectHTTP() error {
	var err error
	// FIXME SEB - Client key not in header but in cookie
	// temporary workaround: used _BuildURL to append uuid=magic in URL
	// map[Set-Cookie:[x-afb-uuid-5678=2b185cc3-276b-4097-91fa-d607eaf937e6; Path=/api; Max-Age=32000000; ...
	//port := strings.Split(xs.BaseURL, ":")[2]
	//"x-afb-uuid-" + port

	xs.client, err = common.HTTPNewClient(xs.BaseURL,
		common.HTTPClientConfig{
			//HeaderClientKeyName: "Xds-Sid",
			HeaderAPIKeyName: "token",
			Apikey:           "HELLO",
			URLPrefix:        "/api/alc",
			CsrfDisable:      true,
			LogOut:           xs.logOut,
			LogPrefix:        "XDSALC: ",
			LogLevel:         common.HTTPLogLevelWarning,
		})

	xs.client.SetLogLevel(xs.Log.Level.String())

	if err != nil {
		msg := ": " + err.Error()
		if strings.Contains(err.Error(), "connection refused") {
			msg = fmt.Sprintf("(url: %s)", xs.BaseURL)
		}
		return fmt.Errorf("ERROR: cannot connect to XDS Low Collector %s", msg)
	}
	if xs.client == nil {
		return fmt.Errorf("ERROR: cannot connect to XDS Low Collector (null client)")
	}

	return nil
}

// _Connect Established HTTP and WS connection
func (xs *XdsLowCollector) _Connect(reConn bool) error {
	var res interface{}
	if err := xs.client.Get(xs._BuildURL("/ping"), &res); err != nil {

		// SEB FIXME tempo Hack
		time.Sleep(time.Microsecond * 300)
		if err := xs.client.Get(xs._BuildURL("/ping"), &res); err != nil {
			// SEB Hack tempo
			// xs.Connected = false
			// if !reConn {
			// 	xs._NotifyState()
			// }
			// return err
		}
	}

	xs.Connected = true

	// Call OnConnect callback
	if xs.cbOnConnect != nil {
		xs.cbOnConnect(xs)
	}

	xs._NotifyState()
	return nil
}

// _NotifyState Send event to notify changes
func (xs *XdsLowCollector) _NotifyState() {

	/* TODO
	evSts := xaapiv1.ServerCfg{
		ID:         xs.ID,
		URL:        xs.BaseURL,
		APIURL:     xs.APIURL,
		PartialURL: xs.PartialURL,
		ConnRetry:  xs.ConnRetry,
		Connected:  xs.Connected,
	}
	if err := xs.events.Emit(xaapiv1.EVTServerConfig, evSts, ""); err != nil {
		xs.Log.Warningf("Cannot notify XdsServer state change: %v", err)
	}
	*/
}