/*
 * Minio Client, (C) 2015 Minio, 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 main

import (
	"os"
	"sort"
	"strings"

	"github.com/minio/cli"
	"github.com/minio/mc/pkg/console"
	"github.com/minio/mc/pkg/probe"
)

// Help message.
var sessionCmd = cli.Command{
	Name:   "session",
	Usage:  "Manage sessions for cp and mirror",
	Action: runSessionCmd,
	CustomHelpTemplate: `NAME:
   mc {{.Name}} - {{.Usage}}

USAGE:
   mc {{.Name}}{{if .Flags}} [ARGS...]{{end}} [SESSION] {{if .Description}}

DESCRIPTION:
   {{.Description}}{{end}}{{if .Flags}}

FLAGS:
   {{range .Flags}}{{.}}
   {{end}}{{ end }}

EXAMPLES:
   1. List sessions
      $ mc {{.Name}} list

   2. Resume session
      $ mc {{.Name}} resume [SESSION]

   3. Clear session
      $ mc {{.Name}} clear [SESSION]|[all]

`,
}

// bySessionWhen is a type for sorting session metadata by time
type bySessionWhen []*sessionV2

func (b bySessionWhen) Len() int           { return len(b) }
func (b bySessionWhen) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
func (b bySessionWhen) Less(i, j int) bool { return b[i].Header.When.Before(b[j].Header.When) }

func listSessions() *probe.Error {
	var bySessions []*sessionV2
	for _, sid := range getSessionIDs() {
		s, err := loadSessionV2(sid)
		if err != nil {
			return err.Trace()
		}
		bySessions = append(bySessions, s)
	}
	// sort sessions based on time
	sort.Sort(bySessionWhen(bySessions))
	for _, session := range bySessions {
		console.Print(session)
	}
	return nil
}

func clearSession(sid string) {
	if sid == "all" {
		for _, sid := range getSessionIDs() {
			session, err := loadSessionV2(sid)
			Fatal(err)
			session.Delete()
		}
		return
	}

	if !isSession(sid) {
		console.Fatalf("Session ‘%s’ not found.\n", sid)
	}

	session, err := loadSessionV2(sid)
	Fatal(err)
	if session != nil {
		session.Delete()
	}
}

func sessionExecute(s *sessionV2) {
	switch s.Header.CommandType {
	case "cp":
		doCopyCmdSession(s)
	case "mirror":
		doMirrorCmdSession(s)
	}
}

func runSessionCmd(ctx *cli.Context) {
	if len(ctx.Args()) < 1 || ctx.Args().First() == "help" {
		cli.ShowCommandHelpAndExit(ctx, "session", 1) // last argument is exit code
	}
	if strings.TrimSpace(ctx.Args().First()) == "" {
		cli.ShowCommandHelpAndExit(ctx, "session", 1) // last argument is exit code
	}
	if !isSessionDirExists() {
		Fatal(createSessionDir())
	}
	switch strings.TrimSpace(ctx.Args().First()) {
	// list resumable sessions
	case "list":
		err := listSessions()
		Fatal(err)
	case "resume":
		if len(ctx.Args().Tail()) != 1 {
			cli.ShowCommandHelpAndExit(ctx, "session", 1) // last argument is exit code
		}
		if strings.TrimSpace(ctx.Args().Tail().First()) == "" {
			cli.ShowCommandHelpAndExit(ctx, "session", 1) // last argument is exit code
		}

		sid := strings.TrimSpace(ctx.Args().Tail().First())

		if _, err := os.Stat(getSessionFile(sid)); err != nil {
			console.Fatalln(errInvalidSessionID{id: sid})
		}
		s, err := loadSessionV2(sid)
		Fatal(err)
		// extra check for testing purposes
		if s == nil {
			return
		}
		{
			savedCwd, err := os.Getwd()
			if err != nil {
				console.Fatalln("Unable to verify your current working folder. %s\n", err)
			}
			if s.Header.RootPath != "" {
				// chdir to RootPath
				os.Chdir(s.Header.RootPath)
			}

			sessionExecute(s)
			{
				err := s.Close()
				if err != nil {
					console.Fatalf("Unable to close session file properly. %s\n", err)
				}
				err = s.Delete()
				if err != nil {
					console.Fatalf("Unable to clear session files properly. %s\n", err)
				}
			}
			// change dir back
			os.Chdir(savedCwd)
		}

	// purge a requested pending session, if "*" purge everything
	case "clear":
		if len(ctx.Args().Tail()) != 1 {
			cli.ShowCommandHelpAndExit(ctx, "session", 1) // last argument is exit code
		}
		if strings.TrimSpace(ctx.Args().Tail().First()) == "" {
			cli.ShowCommandHelpAndExit(ctx, "session", 1) // last argument is exit code
		}
		clearSession(strings.TrimSpace(ctx.Args().Tail().First()))
	default:
		cli.ShowCommandHelpAndExit(ctx, "session", 1) // last argument is exit code
	}
}