// This file is part of MinIO Console Server
// Copyright (c) 2023 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 api

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	"github.com/minio/console/models"
	"github.com/minio/websocket"
)

func (wsc *wsMinioClient) objectManager(session *models.Principal) {
	// Storage of Cancel Contexts for this connection
	cancelContexts := make(map[int64]context.CancelFunc)
	// Initial goroutine
	defer func() {
		// We close socket at the end of requests
		wsc.conn.close()
		for _, c := range cancelContexts {
			// invoke cancel
			c()
		}
	}()

	writeChannel := make(chan WSResponse)
	done := make(chan interface{})

	sendWSResponse := func(r WSResponse) {
		select {
		case writeChannel <- r:
		case <-done:
		}
	}

	// Read goroutine
	go func() {
		defer close(writeChannel)
		for {
			select {
			case <-done:
				return
			default:
			}

			mType, message, err := wsc.conn.readMessage()
			if err != nil {
				LogInfo("Error while reading objectManager message", err)
				return
			}

			if mType == websocket.TextMessage {
				// We get request data & review information
				var messageRequest ObjectsRequest

				err := json.Unmarshal(message, &messageRequest)
				if err != nil {
					LogInfo("Error on message request unmarshal")
					return
				}

				// new message, new context
				ctx, cancel := context.WithCancel(context.Background())

				// We store the cancel func associated with this request
				cancelContexts[messageRequest.RequestID] = cancel

				const itemsPerBatch = 1000
				switch messageRequest.Mode {
				case "close":
					return
				case "cancel":
					// if we have that request id, cancel it
					if cancelFunc, ok := cancelContexts[messageRequest.RequestID]; ok {
						cancelFunc()
						delete(cancelContexts, messageRequest.RequestID)
					}
				case "objects":
					// cancel all previous open objects requests for listing
					for rid, c := range cancelContexts {
						if rid < messageRequest.RequestID {
							// invoke cancel
							c()
						}
					}

					// start listing and writing to web socket
					go func() {
						objectRqConfigs, err := getObjectsOptionsFromReq(messageRequest)
						if err != nil {
							LogInfo(fmt.Sprintf("Error during Objects OptionsParse %s", err.Error()))

							sendWSResponse(WSResponse{
								RequestID:  messageRequest.RequestID,
								Error:      ErrorWithContext(ctx, err),
								Prefix:     messageRequest.Prefix,
								BucketName: messageRequest.BucketName,
							})

							return
						}
						var buffer []ObjectResponse
						for lsObj := range startObjectsListing(ctx, wsc.client, objectRqConfigs) {
							if cancelContexts[messageRequest.RequestID] == nil {
								return
							}
							if lsObj.Err != nil {
								sendWSResponse(WSResponse{
									RequestID:  messageRequest.RequestID,
									Error:      ErrorWithContext(ctx, lsObj.Err),
									Prefix:     messageRequest.Prefix,
									BucketName: messageRequest.BucketName,
								})

								continue
							}
							objItem := ObjectResponse{
								Name:         lsObj.Key,
								Size:         lsObj.Size,
								LastModified: lsObj.LastModified.Format(time.RFC3339),
								VersionID:    lsObj.VersionID,
								IsLatest:     lsObj.IsLatest,
								DeleteMarker: lsObj.IsDeleteMarker,
							}
							buffer = append(buffer, objItem)

							if len(buffer) >= itemsPerBatch {
								sendWSResponse(WSResponse{
									RequestID: messageRequest.RequestID,
									Data:      buffer,
								})
								buffer = nil
							}
						}
						if len(buffer) > 0 {
							sendWSResponse(WSResponse{
								RequestID: messageRequest.RequestID,
								Data:      buffer,
							})
						}

						sendWSResponse(WSResponse{
							RequestID:  messageRequest.RequestID,
							RequestEnd: true,
						})

						// remove the cancellation context
						delete(cancelContexts, messageRequest.RequestID)
					}()
				case "rewind":
					// cancel all previous open objects requests for listing
					for rid, c := range cancelContexts {
						if rid < messageRequest.RequestID {
							// invoke cancel
							c()
						}
					}

					// start listing and writing to web socket
					go func() {
						objectRqConfigs, err := getObjectsOptionsFromReq(messageRequest)
						if err != nil {
							LogInfo(fmt.Sprintf("Error during Objects OptionsParse %s", err.Error()))
							sendWSResponse(WSResponse{
								RequestID:  messageRequest.RequestID,
								Error:      ErrorWithContext(ctx, err),
								Prefix:     messageRequest.Prefix,
								BucketName: messageRequest.BucketName,
							})

							return
						}

						clientIP := wsc.conn.remoteAddress()

						s3Client, err := newS3BucketClient(session, objectRqConfigs.BucketName, objectRqConfigs.Prefix, clientIP)
						if err != nil {
							sendWSResponse(WSResponse{
								RequestID:  messageRequest.RequestID,
								Error:      ErrorWithContext(ctx, err),
								Prefix:     messageRequest.Prefix,
								BucketName: messageRequest.BucketName,
							})

							cancel()
							return
						}

						mcS3C := mcClient{client: s3Client}

						var buffer []ObjectResponse

						for lsObj := range startRewindListing(ctx, mcS3C, objectRqConfigs) {
							if lsObj.Err != nil {
								sendWSResponse(WSResponse{
									RequestID:  messageRequest.RequestID,
									Error:      ErrorWithContext(ctx, lsObj.Err.ToGoError()),
									Prefix:     messageRequest.Prefix,
									BucketName: messageRequest.BucketName,
								})

								continue
							}

							name := strings.Replace(lsObj.URL.Path, fmt.Sprintf("/%s/", objectRqConfigs.BucketName), "", 1)

							objItem := ObjectResponse{
								Name:         name,
								Size:         lsObj.Size,
								LastModified: lsObj.Time.Format(time.RFC3339),
								VersionID:    lsObj.VersionID,
								IsLatest:     lsObj.IsLatest,
								DeleteMarker: lsObj.IsDeleteMarker,
							}
							buffer = append(buffer, objItem)

							if len(buffer) >= itemsPerBatch {
								sendWSResponse(WSResponse{
									RequestID: messageRequest.RequestID,
									Data:      buffer,
								})
								buffer = nil
							}

						}
						if len(buffer) > 0 {
							sendWSResponse(WSResponse{
								RequestID: messageRequest.RequestID,
								Data:      buffer,
							})
						}

						sendWSResponse(WSResponse{
							RequestID:  messageRequest.RequestID,
							RequestEnd: true,
						})

						// remove the cancellation context
						delete(cancelContexts, messageRequest.RequestID)
					}()
				}
			}
		}
	}()

	defer close(done)

	for writeM := range writeChannel {
		jsonData, err := json.Marshal(writeM)
		if err != nil {
			LogInfo("Error while marshaling the response", err)
			return
		}

		err = wsc.conn.writeMessage(websocket.TextMessage, jsonData)
		if err != nil {
			LogInfo("Error while writing the message", err)
			return
		}
	}
}