/**
 * 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 cmd

import (
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"net/http"
	"strings"

	"github.com/aurora-scheduler/australis/internal"
	realis "github.com/aurora-scheduler/gorealis/v2"
	"github.com/aurora-scheduler/gorealis/v2/gen-go/apache/aurora"
	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
)

const (
	localAgentStateURL = "http://127.0.0.1:5051/state"
)

type mesosAgentState struct {
	Flags mesosAgentFlags `json:"flags,omitempty"`
}

type mesosAgentFlags struct {
	Master    string `json:"master,omitempty"`
	hasMaster bool   // indicates if the master flag contains direct Master's address
}

func init() {
	rootCmd.AddCommand(fetchCmd)

	// Sub-commands

	// Fetch Task Config
	fetchCmd.AddCommand(fetchTaskCmd)

	// Fetch Task Config
	fetchTaskCmd.AddCommand(taskConfigCmd)
	taskConfigCmd.Flags().StringVarP(env, "environment", "e", "", "Aurora Environment")
	taskConfigCmd.Flags().StringVarP(role, "role", "r", "", "Aurora Role")
	taskConfigCmd.Flags().StringVarP(name, "name", "n", "", "Aurora Name")

	// Fetch Task Status
	fetchTaskCmd.AddCommand(taskStatusCmd)
	taskStatusCmd.Flags().StringVarP(env, "environment", "e", "", "Aurora Environment")
	taskStatusCmd.Flags().StringVarP(role, "role", "r", "", "Aurora Role")
	taskStatusCmd.Flags().StringVarP(name, "name", "n", "", "Aurora Name")

	/* Fetch Leader */
	leaderCmd.Flags().String("zkPath", "/aurora/scheduler", "Zookeeper node path where leader election happens")

	fetchCmd.AddCommand(leaderCmd)

	// Hijack help function to hide unnecessary global flags
	help := leaderCmd.HelpFunc()
	leaderCmd.SetHelpFunc(func(cmd *cobra.Command, s []string) {
		if cmd.HasInheritedFlags() {
			cmd.InheritedFlags().VisitAll(func(f *pflag.Flag) {
				if f.Name != "logLevel" {
					f.Hidden = true
				}
			})
		}
		help(cmd, s)
	})

	mesosLeaderCmd.Flags().String("zkPath", "/mesos", "Zookeeper node path where mesos leader election happens")
	mesosCmd.AddCommand(mesosLeaderCmd)

	fetchCmd.AddCommand(mesosCmd)

	// Hijack help function to hide unnecessary global flags
	mesosCmd.SetHelpFunc(func(cmd *cobra.Command, s []string) {
		if cmd.HasInheritedFlags() {
			cmd.InheritedFlags().VisitAll(func(f *pflag.Flag) {
				if f.Name != "logLevel" {
					f.Hidden = true
				}
			})
		}
		help(cmd, s)
	})

	// Fetch jobs
	fetchJobsCmd.Flags().StringVarP(role, "role", "r", "", "Aurora Role")
	fetchCmd.AddCommand(fetchJobsCmd)

	// Fetch Status
	fetchCmd.AddCommand(fetchStatusCmd)
}

var fetchCmd = &cobra.Command{
	Use:   "fetch",
	Short: "Fetch information from Aurora",
}

var fetchTaskCmd = &cobra.Command{
	Use:   "task",
	Short: "Task information from Aurora",
}

var taskConfigCmd = &cobra.Command{
	Use:   "config",
	Short: "Fetch a list of task configurations from Aurora.",
	Long:  `To be written.`,
	Run:   fetchTasksConfig,
}

var taskStatusCmd = &cobra.Command{
	Use:   "status",
	Short: "Fetch task status for a Job key.",
	Long:  `To be written.`,
	Run:   fetchTasksStatus,
}

var leaderCmd = &cobra.Command{
	Use:               "leader [zkNode0, zkNode1, ...zkNodeN]",
	PersistentPreRun:  func(cmd *cobra.Command, args []string) {}, // We don't need a realis client for this cmd
	PersistentPostRun: func(cmd *cobra.Command, args []string) {}, // We don't need a realis client for this cmd
	PreRun:            setConfig,
	Args:              cobra.MinimumNArgs(1),
	Short:             "Fetch current Aurora leader given Zookeeper nodes. ",
	Long: `Gets the current leading aurora scheduler instance using information from Zookeeper path.
Pass Zookeeper nodes separated by a space as an argument to this command.`,
	Run: fetchLeader,
}

var mesosCmd = &cobra.Command{
	Use:    "mesos",
	PreRun: setConfig,
	Short:  "Fetch information from Mesos.",
}

var mesosLeaderCmd = &cobra.Command{
	Use:               "leader [zkNode0, zkNode1, ...zkNodeN]",
	PersistentPreRun:  func(cmd *cobra.Command, args []string) {}, // We don't need a realis client for this cmd
	PersistentPostRun: func(cmd *cobra.Command, args []string) {}, // We don't need a realis client for this cmd
	PreRun:            setConfig,
	Short:             "Fetch current Mesos-master leader given Zookeeper nodes.",
	Long: `Gets the current leading Mesos-master instance using information from Zookeeper path.
Pass Zookeeper nodes separated by a space as an argument to this command. If no nodes are provided, 
it fetches leader from local Mesos agent or Zookeeper`,
	Run: fetchMesosLeader,
}

var fetchJobsCmd = &cobra.Command{
	Use:   "jobs",
	Short: "Fetch a list of task Aurora running under a role.",
	Long:  `To be written.`,
	Run:   fetchJobs,
}

var fetchStatusCmd = &cobra.Command{
	Use:   "status",
	Short: "Fetch the maintenance status of a node from Aurora",
	Long:  `This command will print the actual status of the mesos agent nodes in Aurora server`,
	Run:   fetchHostStatus,
}

func fetchTasksConfig(cmd *cobra.Command, args []string) {
	log.Infof("Fetching job configuration for [%s/%s/%s] \n", *env, *role, *name)

	// Task Query takes nil for values it shouldn't need to match against.
	// This allows us to potentially more expensive calls for specific environments, roles, or job names.
	if *env == "" {
		env = nil
	}
	if *role == "" {
		role = nil
	}
	if *role == "" {
		role = nil
	}
	//TODO: Add filtering down by status
	taskQuery := &aurora.TaskQuery{Environment: env, Role: role, JobName: name}

	tasks, err := client.GetTasksWithoutConfigs(taskQuery)
	if err != nil {
		log.Fatalf("error: %+v", err)
	}

	if toJson {
		fmt.Println(internal.ToJSON(tasks))
	} else {
		for _, t := range tasks {
			fmt.Println(t)
		}
	}
}

func fetchTasksStatus(cmd *cobra.Command, args []string) {
	log.Infof("Fetching task status for [%s/%s/%s] \n", *env, *role, *name)

	// Task Query takes nil for values it shouldn't need to match against.
	// This allows us to potentially more expensive calls for specific environments, roles, or job names.
	if *env == "" {
		env = nil
	}
	if *role == "" {
		role = nil
	}
	if *role == "" {
		role = nil
	}
	// TODO(rdelvalle): Add filtering down by status
	taskQuery := &aurora.TaskQuery{
		Environment: env,
		Role:        role,
		JobName:     name,
		Statuses:    aurora.LIVE_STATES}

	tasks, err := client.GetTaskStatus(taskQuery)
	if err != nil {
		log.Fatalf("error: %+v", err)
	}

	if toJson {
		fmt.Println(internal.ToJSON(tasks))
	} else {
		for _, t := range tasks {
			fmt.Println(t)
		}
	}
}

func fetchHostStatus(cmd *cobra.Command, args []string) {
	log.Infof("Fetching maintenance status for %v \n", args)
	result, err := client.MaintenanceStatus(args...)
	if err != nil {
		log.Fatalf("error: %+v\n", err)
	}

	if toJson {
		fmt.Println(internal.ToJSON(result.Statuses))
	} else {
		for _, k := range result.GetStatuses() {
			fmt.Printf("Result: %s:%s\n", k.Host, k.Mode)
		}
	}
}

func fetchLeader(cmd *cobra.Command, args []string) {
	log.Infof("Fetching leader from %v \n", args)

	if len(args) < 1 {
		log.Fatalln("At least one Zookeeper node address must be passed in.")
	}

	url, err := realis.LeaderFromZKOpts(realis.ZKEndpoints(args...), realis.ZKPath(cmd.Flag("zkPath").Value.String()))

	if err != nil {
		log.Fatalf("error: %+v\n", err)
	}

	fmt.Println(url)
}

func fetchMesosLeader(cmd *cobra.Command, args []string) {
	if len(args) < 1 {
		mesosAgentFlags, err := fetchMasterFromAgent(localAgentStateURL)
		if err != nil || mesosAgentFlags.Master == "" {
			log.Debugf("unable to fetch Mesos leader via local Mesos agent: %v", err)
			args = append(args, "localhost")
		} else if mesosAgentFlags.hasMaster {
			fmt.Println(mesosAgentFlags.Master)
			return
		} else {
			args = append(args, strings.Split(mesosAgentFlags.Master, ",")...)
		}
	}
	log.Infof("Fetching Mesos-master leader from Zookeeper node(s): %v \n", args)

	url, err := realis.MesosFromZKOpts(realis.ZKEndpoints(args...), realis.ZKPath(cmd.Flag("zkPath").Value.String()))

	if err != nil {
		log.Fatalf("error: %+v\n", err)
	}

	fmt.Println(url)
}

func fetchMasterFromAgent(url string) (mesosAgentFlags mesosAgentFlags, err error) {
	resp, err := http.Get(url)
	if err != nil {
		return
	}
	if resp.StatusCode != 200 {
		return
	}
	defer resp.Body.Close()

	state := &mesosAgentState{}
	err = json.NewDecoder(resp.Body).Decode(state)
	if err != nil {
		return
	}
	mesosAgentFlags = state.Flags
	err = updateMasterFlag(&mesosAgentFlags)
	return
}

/*
 Master flag can be passed as one of :
 host:port
 zk://host1:port1,host2:port2,.../path
 zk://username:password@host1:port1,host2:port2,.../path
 file:///path/to/file
 This function takes care of all the above cases and updates flags with parsed values
*/
func updateMasterFlag(flags *mesosAgentFlags) error {
	zkPathPrefix := "zk://"
	filePathPrefix := "file://"
	if strings.HasPrefix(flags.Master, zkPathPrefix) {
		beginIndex := len(zkPathPrefix)
		if strings.Contains(flags.Master, "@") {
			beginIndex = strings.Index(flags.Master, "@") + 1
		}
		flags.Master = flags.Master[beginIndex:strings.LastIndex(flags.Master, "/")]
	} else if strings.HasPrefix(flags.Master, filePathPrefix) {
		content, err := ioutil.ReadFile(flags.Master)
		if err != nil {
			return err
		}
		if strings.Contains(string(content), filePathPrefix) {
			return errors.New("invalid master file content")
		}
		flags.Master = string(content)
		return updateMasterFlag(flags)
	} else {
		flags.hasMaster = true
	}
	return nil
}

// TODO: Expand this to be able to filter by job name and environment.
func fetchJobs(cmd *cobra.Command, args []string) {
	log.Infof("Fetching tasks under role: %s \n", *role)

	if *role == "" {
		log.Fatalln("Role must be specified.")
	}

	if *role == "*" {
		log.Warnln("This is an expensive operation.")
		*role = ""
	}

	result, err := client.GetJobs(*role)

	if err != nil {
		log.Fatalf("error: %+v", err)
	}

	if toJson {
		var configSlice []*aurora.JobConfiguration

		for _, config := range result.GetConfigs() {
			configSlice = append(configSlice, config)
		}

		fmt.Println(internal.ToJSON(configSlice))
	} else {
		for jobConfig := range result.GetConfigs() {
			fmt.Println(jobConfig)
		}
	}
}