// This file is part of MinIO Console Server
// Copyright (c) 2021 MinIO, Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package restapi

import (
	"context"
	"encoding/json"
	"log"
	"net/http"
	"time"

	"errors"

	"github.com/gorilla/websocket"
	madmin "github.com/minio/minio/pkg/madmin"
)

// startHealthInfo starts fetching mc.ServerHealthInfo and
// sends messages with the corresponding data on the websocket connection
func startHealthInfo(ctx context.Context, conn WSConn, client MinioAdmin, deadline *time.Duration) error {
	if deadline == nil {
		return errors.New("duration can't be nil on startHealthInfo")
	}

	// Fetch info of all servers (cluster or single server)
	healthDataTypes := []madmin.HealthDataType{
		madmin.HealthDataTypePerfDrive,
		madmin.HealthDataTypePerfNet,
		madmin.HealthDataTypeMinioInfo,
		madmin.HealthDataTypeMinioConfig,
		madmin.HealthDataTypeSysCPU,
		madmin.HealthDataTypeSysDiskHw,
		madmin.HealthDataTypeSysDocker,
		madmin.HealthDataTypeSysOsInfo,
		madmin.HealthDataTypeSysLoad,
		madmin.HealthDataTypeSysMem,
		madmin.HealthDataTypeSysNet,
		madmin.HealthDataTypeSysProcess,
	}

	healthChan := client.serverHealthInfo(ctx, healthDataTypes, *deadline)
	// wait for events to occur
	for {
		select {
		// return if context ends
		case <-ctx.Done():
			return nil
		case adminHealthInfo, ok := <-healthChan:
			// zero value returned because the channel is closed and empty
			if !ok {
				return nil
			}
			if adminHealthInfo.Error != "" {
				return errors.New(adminHealthInfo.Error)
			}
			// Serialize message to be sent
			bytes, err := json.Marshal(adminHealthInfo)
			if err != nil {
				log.Println("error on json.Marshal:", err)
				return err
			}
			// Send Message through websocket connection
			err = conn.writeMessage(websocket.TextMessage, bytes)
			if err != nil {
				log.Println("error writeMessage:", err)
				return err
			}
		}
	}
}

// getHealthInfoOptionsFromReq gets duration for startHealthInfo request
// path come as : `/health-info?deadline=2h`
func getHealthInfoOptionsFromReq(req *http.Request) (*time.Duration, error) {
	deadlineDuration, err := time.ParseDuration(req.FormValue("deadline"))
	if err != nil {
		return nil, err
	}
	return &deadlineDuration, nil
}