// Copyright 2017 Google Inc.
//
// 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 apiGatewayConfDeploy

import (
	"bytes"
	"encoding/json"
	"fmt"
	"github.com/gorilla/mux"
	"io"
	"io/ioutil"
	"net/http"
	"net/url"
	"regexp"
	"strconv"
	"sync/atomic"
	"time"
)

// todo: the full set of states should probably be RECEIVED, READY, FAIL, SUCCESS
const (
	RESPONSE_STATUS_SUCCESS = "SUCCESS"
	RESPONSE_STATUS_FAIL    = "FAIL"
)

const (
	TRACKER_ERR_BUNDLE_DOWNLOAD_TIMEOUT = iota + 1
)

const (
	deploymentsEndpoint  = "/configurations"
	blobEndpointPath     = "/blobs"
	blobEndpoint         = blobEndpointPath + "/{blobId}"
	configStatusEndpoint = "/configurations/status"
	heartbeatEndpoint    = "/heartbeat/{uuid}"
	registerEndpoint     = "/register/{uuid}"
)

const (
	API_ERR_BAD_BLOCK = iota + 1
	API_ERR_INTERNAL
	API_ERR_INVALID_PARAMETERS
	API_ERR_FROM_TRACKER
)

const (
	sqlTimeFormat    = "2006-01-02 15:04:05.999 -0700 MST"
	iso8601          = "2006-01-02T15:04:05.999Z07:00"
	sqliteTimeFormat = "2006-01-02 15:04:05.999-07:00"
	changeTimeFormat = "2006-01-02 15:04:05.999"
)

const (
	kindCollection = "Collection"
)

const (
	headerSteam = "application/octet-stream"
)

type deploymentsResult struct {
	deployments []DataDeployment
	err         error
	eTag        string
}

type errorResponse struct {
	ErrorCode int    `json:"errorCode"`
	Reason    string `json:"reason"`
}

type ApiDeploymentDetails struct {
	Self            string `json:"self"`
	Name            string `json:"name"`
	Type            string `json:"type"`
	Revision        string `json:"revision"`
	BeanBlobUrl     string `json:"beanBlob"`
	Org             string `json:"orgId"`
	Env             string `json:"envId"`
	ResourceBlobUrl string `json:"resourceBlob"`
	Path            string `json:"path"`
	Created         string `json:"created"`
	Updated         string `json:"updated"`
}

type ApiDeploymentResponse struct {
	Kind                   string                 `json:"kind"`
	Self                   string                 `json:"self"`
	ApiDeploymentsResponse []ApiDeploymentDetails `json:"contents"`
}

//TODO add support for block and subscriber
type apiManagerInterface interface {
	InitAPI()
	//addChangedDeployment(string)
	//distributeEvents()
}

type apiManager struct {
	dbMan                dbManagerInterface
	trackerCl            trackerClientInterface
	deploymentsEndpoint  string
	blobEndpoint         string
	configStatusEndpoint string
	heartbeatEndpoint    string
	registerEndpoint     string
	eTag                 int64
	deploymentsChanged   chan interface{}
	addSubscriber        chan chan deploymentsResult
	removeSubscriber     chan chan deploymentsResult
	apiInitialized       bool
}

func (a *apiManager) InitAPI() {
	if a.apiInitialized {
		return
	}
	services.API().HandleFunc(a.deploymentsEndpoint, a.apiGetCurrentDeployments).Methods("GET")
	services.API().HandleFunc(a.blobEndpoint, a.apiReturnBlobData).Methods("GET")
	services.API().HandleFunc(a.configStatusEndpoint, a.apiPutConfigStatus).Methods("PUT")
	services.API().HandleFunc(a.heartbeatEndpoint, a.apiPutHeartbeat).Methods("PUT")
	services.API().HandleFunc(a.registerEndpoint, a.apiPutRegister).Methods("PUT")
	a.apiInitialized = true
	log.Debug("API endpoints initialized")
}

func (a *apiManager) addChangedDeployment(id string) {
	a.deploymentsChanged <- id
}

func (a *apiManager) writeError(w http.ResponseWriter, status int, code int, reason string) {
	w.WriteHeader(status)
	e := errorResponse{
		ErrorCode: code,
		Reason:    reason,
	}
	bytes, err := json.Marshal(e)
	if err != nil {
		log.Errorf("unable to marshal errorResponse: %v", err)
	} else {
		w.Write(bytes)
	}
	log.Debugf("sending %d error to client: %s", status, reason)
}

func (a *apiManager) writeInternalError(w http.ResponseWriter, err string) {
	a.writeError(w, http.StatusInternalServerError, API_ERR_INTERNAL, err)
}

func (a *apiManager) debounce(in chan interface{}, out chan []interface{}, window time.Duration) {
	send := func(toSend []interface{}) {
		if toSend != nil {
			log.Debugf("debouncer sending: %v", toSend)
			out <- toSend
		}
	}
	var toSend []interface{}
	for {
		select {
		case incoming, ok := <-in:
			if ok {
				log.Debugf("debouncing %v", incoming)
				toSend = append(toSend, incoming)
			} else {
				send(toSend)
				log.Debugf("closing debouncer")
				close(out)
				return
			}
		case <-time.After(window):
			send(toSend)
			toSend = nil
		}
	}
}

//TODO get notified when deployments ready
/*
func (a *apiManager) distributeEvents() {
	subscribers := make(map[chan deploymentsResult]bool)
	deliverDeployments := make(chan []interface{}, 1)

	go a.debounce(a.deploymentsChanged, deliverDeployments, debounceDuration)

	for {
		select {
		case _, ok := <-deliverDeployments:
			if !ok {
				return // todo: using this?
			}
			subs := subscribers
			subscribers = make(map[chan deploymentsResult]bool)
			go func() {
				eTag := a.incrementETag()
				deployments, err := a.dbMan.getUnreadyDeployments()
				log.Debugf("delivering deployments to %d subscribers", len(subs))
				for subscriber := range subs {
					log.Debugf("delivering to: %v", subscriber)
					subscriber <- deploymentsResult{deployments, err, eTag}
				}
			}()
		case subscriber := <-a.addSubscriber:
			log.Debugf("Add subscriber: %v", subscriber)
			subscribers[subscriber] = true
		case subscriber := <-a.removeSubscriber:
			log.Debugf("Remove subscriber: %v", subscriber)
			delete(subscribers, subscriber)
		}
	}
}
*/

// TODO use If-None-Match and ETag
func (a *apiManager) apiReturnBlobData(w http.ResponseWriter, r *http.Request) {

	vars := mux.Vars(r)
	blobId := vars["blobId"]
	fs, err := a.dbMan.getLocalFSLocation(blobId)
	if err != nil {
		a.writeInternalError(w, "BlobId "+blobId+" has no mapping blob file")
		return
	}
	byte, err := ioutil.ReadFile(fs)
	if err != nil {
		a.writeInternalError(w, err.Error())
		return
	}
	_, err = io.Copy(w, bytes.NewReader(byte))
	if err != nil {
		a.writeInternalError(w, err.Error())
	}
	w.Header().Set("Content-Type", headerSteam)

}

func (a *apiManager) apiGetCurrentDeployments(w http.ResponseWriter, r *http.Request) {

	// If returning without a bundle (immediately or after timeout), status = 404
	// If returning If-None-Match value is equal to current deployment, status = 304
	// If returning a new value, status = 200

	// If timeout > 0 AND there is no deployment (or new deployment) available (per If-None-Match), then
	// block for up to the specified number of seconds until a new deployment becomes available.
	b := r.URL.Query().Get("block")
	var timeout int
	if b != "" {
		var err error
		timeout, err = strconv.Atoi(b)
		if err != nil {
			a.writeError(w, http.StatusBadRequest, API_ERR_BAD_BLOCK, "bad block value, must be number of seconds")
			return
		}
	}
	log.Debugf("api timeout: %d", timeout)

	// If If-None-Match header matches the ETag of current bundle list AND if the request does NOT have a 'block'
	// query param > 0, the server returns a 304 Not Modified response indicating that the client already has the
	// most recent bundle list.
	ifNoneMatch := r.Header.Get("If-None-Match")
	log.Debugf("if-none-match: %s", ifNoneMatch)

	// send unmodified if matches prior eTag and no timeout
	eTag := a.getETag()
	if eTag == ifNoneMatch && timeout == 0 {
		w.WriteHeader(http.StatusNotModified)
		return
	}

	// send results if different eTag
	if eTag != ifNoneMatch {
		a.sendReadyDeployments(w)
		return
	}

	// otherwise, subscribe to any new deployment changes
	var newDeploymentsChannel chan deploymentsResult
	if timeout > 0 && ifNoneMatch != "" {
		//TODO handle block
		//newDeploymentsChannel = make(chan deploymentsResult, 1)
		//a.addSubscriber <- newDeploymentsChannel
	}

	log.Debug("Blocking request... Waiting for new Deployments.")

	select {
	case result := <-newDeploymentsChannel:
		if result.err != nil {
			a.writeInternalError(w, "Database error")
		} else {
			a.sendDeployments(w, result.deployments, result.eTag)
		}

	case <-time.After(time.Duration(timeout) * time.Second):
		a.removeSubscriber <- newDeploymentsChannel
		log.Debug("Blocking deployment request timed out.")
		if ifNoneMatch != "" {
			w.WriteHeader(http.StatusNotModified)
		} else {
			a.sendReadyDeployments(w)
		}
	}
}

func (a *apiManager) sendReadyDeployments(w http.ResponseWriter) {
	eTag := a.getETag()
	deployments, err := a.dbMan.getReadyDeployments()
	if err != nil {
		a.writeInternalError(w, fmt.Sprintf("Database error: %s", err.Error()))
		return
	}
	a.sendDeployments(w, deployments, eTag)
}

func (a *apiManager) sendDeployments(w http.ResponseWriter, dataDeps []DataDeployment, eTag string) {

	apiDeps := ApiDeploymentResponse{}
	apiDepDetails := make([]ApiDeploymentDetails, 0)

	apiDeps.Kind = kindCollection
	apiDeps.Self = getHttpHost() + a.deploymentsEndpoint

	for _, d := range dataDeps {
		apiDepDetails = append(apiDepDetails, ApiDeploymentDetails{
			Self:            apiDeps.Self + "/" + d.ID,
			Name:            d.Name,
			Type:            d.Type,
			Revision:        d.Revision,
			BeanBlobUrl:     getBlobUrl(d.BlobID),
			Org:             d.OrgID,
			Env:             d.EnvID,
			ResourceBlobUrl: getBlobUrl(d.BlobResourceID),
			Path:            d.Path,
			Created:         convertTime(d.Created),
			Updated:         convertTime(d.Updated),
		})
	}
	apiDeps.ApiDeploymentsResponse = apiDepDetails

	b, err := json.Marshal(apiDeps)
	if err != nil {
		log.Errorf("unable to marshal deployments: %v", err)
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	log.Debugf("sending deployments %s: %s", eTag, b)
	w.Header().Set("ETag", eTag)
	w.Write(b)
}

func (a *apiManager) apiPutRegister(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	uuid := vars["uuid"]

	// parse & validate body
	body := r.Body
	defer body.Close()
	bodyBytes, err := ioutil.ReadAll(body)
	if err != nil {
		log.Errorf("apiPutRegister error: %v", err)
		a.writeError(w, http.StatusInternalServerError, API_ERR_INTERNAL, "Failed to read request body.")
		return
	}

	reqBody := &registerBody{}
	err = json.Unmarshal(bodyBytes, reqBody)
	if err != nil {
		log.Errorf("apiPutRegister error: %v", err)
		a.writeError(w, http.StatusInternalServerError, API_ERR_INTERNAL, "Failed to read request body.")
		return
	}

	isValid, reason := reqBody.validateBody(uuid)
	if !isValid {
		a.writeError(w, http.StatusBadRequest, API_ERR_INVALID_PARAMETERS, reason)
		return
	}

	// connect to tracker
	trackerResp := a.trackerCl.putRegister(uuid, reqBody)

	// write response
	switch trackerResp.code {
	case http.StatusOK:
		a.writePutRegisterResp(w, trackerResp)
	default:
		log.Debugf("apiPutRegister code: %v Reason: %v", trackerResp.code, string(trackerResp.body))
		a.writeError(w, trackerResp.code, API_ERR_FROM_TRACKER, string(trackerResp.body))
	}

}

func (a *apiManager) apiPutConfigStatus(w http.ResponseWriter, r *http.Request) {

	// parse & validate body
	body := r.Body
	defer body.Close()
	bodyBytes, err := ioutil.ReadAll(body)
	if err != nil {
		log.Errorf("apiPutConfigStatus error: %v", err)
		a.writeError(w, http.StatusInternalServerError, API_ERR_INTERNAL, "Failed to read request body.")
		return
	}

	reqBody := &configStatusBody{}
	err = json.Unmarshal(bodyBytes, reqBody)
	if err != nil {
		log.Errorf("apiPutConfigStatus error: %v", err)
		a.writeError(w, http.StatusInternalServerError, API_ERR_INTERNAL, "Failed to read request body.")
		return
	}

	isValid, reason := reqBody.validateBody()
	if !isValid {
		a.writeError(w, http.StatusBadRequest, API_ERR_INVALID_PARAMETERS, reason)
		return
	}

	// connect to tracker
	trackerResp := a.trackerCl.putConfigStatus(reqBody)

	// write response
	switch trackerResp.code {
	case http.StatusOK:
		a.writeConfigStatusResp(w, trackerResp)
	default:
		log.Infof("apiPutConfigStatus code: %v Reason: %v", trackerResp.code, string(trackerResp.body))
		a.writeError(w, trackerResp.code, API_ERR_FROM_TRACKER, string(trackerResp.body))
	}
}

func (a *apiManager) apiPutHeartbeat(w http.ResponseWriter, r *http.Request) {
	// parse & validate
	vars := mux.Vars(r)
	uuid := vars["uuid"]
	if !isValidUuid(uuid) {
		a.writeError(w, http.StatusBadRequest, API_ERR_INVALID_PARAMETERS, "Bad/Missing gateway UUID")
		return
	}
	reported := r.Header.Get("reportedTime")
	if reported == "" || !isIso8601(reported) {
		a.writeError(w, http.StatusBadRequest, API_ERR_INVALID_PARAMETERS, "Bad/Missing reportedTime")
		return
	}

	// connect to tracker
	trackerResp := a.trackerCl.putHeartbeat(uuid, reported)

	// write response
	switch trackerResp.code {
	case http.StatusOK:
		a.writePutHeartbeatResp(w, trackerResp)
	default:
		log.Infof("apiPutHeartbeat code: %v Reason: %v", trackerResp.code, string(trackerResp.body))
		a.writeError(w, trackerResp.code, API_ERR_FROM_TRACKER, string(trackerResp.body))
	}
}

func (a *apiManager) writeConfigStatusResp(w http.ResponseWriter, tr *trackerResponse) {
	a.writeSimpleResp(w, tr)
}

func (a *apiManager) writePutRegisterResp(w http.ResponseWriter, tr *trackerResponse) {
	a.writeSimpleResp(w, tr)
}

func (a *apiManager) writePutHeartbeatResp(w http.ResponseWriter, tr *trackerResponse) {
	a.writeSimpleResp(w, tr)
}

func (a *apiManager) writeSimpleResp(w http.ResponseWriter, tr *trackerResponse) {
	if tr.contentType != "" {
		w.Header().Add("Content-type", tr.contentType)
	}
	_, err := w.Write(tr.body)
	if err != nil {
		log.Errorf("failed to write response: %v", err)
		a.writeError(w, http.StatusInternalServerError, API_ERR_INTERNAL, err.Error())
	}
}

// call whenever the list of deployments changes
func (a *apiManager) incrementETag() string {
	e := atomic.AddInt64(&a.eTag, 1)
	return strconv.FormatInt(e, 10)
}

func (a *apiManager) getETag() string {
	e := atomic.LoadInt64(&a.eTag)
	return strconv.FormatInt(e, 10)
}

// escape the blobId into url
func getBlobUrl(blobId string) string {
	if blobId == "" {
		return ""
	}
	return getHttpHost() + "/blobs/" + url.PathEscape(blobId)
}

func convertTime(t string) string {
	if t == "" {
		return ""
	}
	formats := []string{sqliteTimeFormat, sqlTimeFormat, iso8601, time.RFC3339, changeTimeFormat}
	for _, f := range formats {
		timestamp, err := time.Parse(f, t)
		if err == nil {
			return timestamp.Format(iso8601)
		}
	}
	log.Error("convertTime: Unsupported time format: " + t)
	return t
}

func getHttpHost() string {

	configuredEndpoint := config.GetString(configBundleBlobDownloadEndpoint)
	if configuredEndpoint != "" {
		return configuredEndpoint
	}
	// apid-core has to set this according to the protocol apid is to be run: http/https
	proto := config.GetString(configProtocol)
	if proto == "" {
		proto = "http"
	}
	proto = proto + "://" + config.GetString(configAPIListen)
	return proto
}

func isValidUuid(uuid string) bool {
	r := regexp.MustCompile("^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-4[a-fA-F0-9]{3}-[8|9|aA|bB][a-fA-F0-9]{3}-[a-fA-F0-9]{12}$")
	return r.MatchString(uuid)
}

func isIso8601(t string) bool {

	if _, err := time.Parse(iso8601, t); err == nil {
		return true
	}
	if _, err := time.Parse(time.RFC3339, t); err == nil {
		return true
	}

	return false
}

type registerBody struct {
	Uuid         string `json:"uuid"`
	Pod          string `json:"pod"`
	PodType      string `json:"podType"`
	ReportedTime string `json:"reportedTime"`
	Name         string `json:"name"`
	Type         string `json:"type"`
}

func (body *registerBody) validateBody(uuid string) (bool, string) {
	switch {
	case uuid != body.Uuid:
		return false, "UUID in path mismatch UUID in body"
	case !isValidUuid(body.Uuid):
		return false, "Bad/Missing gateway UUID"
	case body.ReportedTime == "" || !isIso8601(body.ReportedTime):
		return false, "Bad/Missing gateway reportedTime"
	}
	return true, ""
}

type configStatusBody struct {
	StatusDetails []statusDetailsJson `json:"statusDetails"`
	ServiceId     string              `json:"serviceId"`
	ReportedTime  string              `json:"reportedTime"`
}

func (body *configStatusBody) validateBody() (bool, string) {
	switch {
	case !isValidUuid(body.ServiceId):
		return false, "Bad/Missing gateway ServiceId"
	case body.ReportedTime == "" || !isIso8601(body.ReportedTime):
		return false, "Bad/Missing gateway reportedTime"
	}

	for _, s := range body.StatusDetails {
		isValid, reason := s.validateBody()
		if !isValid {
			return false, reason
		}
	}
	return true, ""
}

type statusDetailsJson struct {
	Status          string `json:"status"`
	ConfigurationId string `json:"configurationId"`
	ErrorCode       string `json:"errorCode"`
	Message         string `json:"message"`
}

func (s *statusDetailsJson) validateBody() (bool, string) {
	switch {
	case s.Status == "":
		return false, "Bad/Missing configuration Status"
	case s.ConfigurationId == "":
		return false, "Bad/Missing configuration ConfigurationId"
	}
	return true, ""
}