/*
Copyright (c) 2014-2016 VMware, Inc. All Rights Reserved.

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 cli

import (
	"context"
	"flag"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"text/tabwriter"

	"github.com/vmware/govmomi/vim25/types"
)

type HasFlags interface {
	// Register may be called more than once and should be idempotent.
	Register(ctx context.Context, f *flag.FlagSet)

	// Process may be called more than once and should be idempotent.
	Process(ctx context.Context) error
}

type Command interface {
	HasFlags

	Run(ctx context.Context, f *flag.FlagSet) error
}

func generalHelp(w io.Writer, filter string) {
	var cmds, matches []string
	for name := range commands {
		cmds = append(cmds, name)

		if filter != "" && strings.Contains(name, filter) {
			matches = append(matches, name)
		}
	}

	if len(matches) == 0 {
		fmt.Fprintf(w, `Usage: %[1]s <COMMAND> [COMMON OPTIONS] [PATH]...

govmomi is a Go library for interacting with VMware vSphere APIs (ESXi and/or
vCenter Server).
It is licensed under the Apache License, Version 2.0

%[1]s is the CLI for govmomi.

The available commands are listed below. A detailed description of each
command can be displayed with "govc <COMMAND> -h". The description of all
commands can be also found at https://via.vmw.com/GJ98hk .

Examples:
  show usage of a command:       govc <COMMAND> -h
  show toplevel structure:       govc ls
  show datacenter summary:       govc datacenter.info
  show all VMs:                  govc find -type m
  upload a ISO file:             govc datastore.upload -ds datastore1 ./config.iso vm-name/config.iso

Common options:
  -h                        Show this message
  -cert=                    Certificate [GOVC_CERTIFICATE]
  -debug=false              Store debug logs [GOVC_DEBUG]
  -trace=false              Write SOAP/REST traffic to stderr
  -verbose=false            Write request/response data to stderr
  -dump=false               Enable output dump
  -json=false               Enable JSON output
  -xml=false                Enable XML output
  -k=false                  Skip verification of server certificate [GOVC_INSECURE]
  -key=                     Private key [GOVC_PRIVATE_KEY]
  -persist-session=true     Persist session to disk [GOVC_PERSIST_SESSION]
  -tls-ca-certs=            TLS CA certificates file [GOVC_TLS_CA_CERTS]
  -tls-known-hosts=         TLS known hosts file [GOVC_TLS_KNOWN_HOSTS]
  -u=                       ESX or vCenter URL [GOVC_URL]
  -vim-namespace=urn:vim25  Vim namespace [GOVC_VIM_NAMESPACE]
  -vim-version=6.0          Vim version [GOVC_VIM_VERSION]
  -dc=                      Datacenter [GOVC_DATACENTER]
  -host.dns=                Find host by FQDN
  -host.ip=                 Find host by IP address
  -host.ipath=              Find host by inventory path
  -host.uuid=               Find host by UUID
  -vm.dns=                  Find VM by FQDN
  -vm.ip=                   Find VM by IP address
  -vm.ipath=                Find VM by inventory path
  -vm.path=                 Find VM by path to .vmx file
  -vm.uuid=                 Find VM by UUID

Available commands:
`, filepath.Base(os.Args[0]))

	} else {
		fmt.Fprintf(w, "%s: command '%s' not found, did you mean:\n", os.Args[0], filter)
		cmds = matches
	}

	sort.Strings(cmds)
	for _, name := range cmds {
		fmt.Fprintf(w, "  %s\n", name)
	}
}

func commandHelp(w io.Writer, name string, cmd Command, f *flag.FlagSet) {
	type HasUsage interface {
		Usage() string
	}

	fmt.Fprintf(w, "Usage: %s %s [OPTIONS]", os.Args[0], name)
	if u, ok := cmd.(HasUsage); ok {
		fmt.Fprintf(w, " %s", u.Usage())
	}
	fmt.Fprintf(w, "\n")

	type HasDescription interface {
		Description() string
	}

	if u, ok := cmd.(HasDescription); ok {
		fmt.Fprintf(w, "\n%s\n", u.Description())
	}

	n := 0
	f.VisitAll(func(_ *flag.Flag) {
		n += 1
	})

	if n > 0 {
		fmt.Fprintf(w, "\nOptions:\n")
		tw := tabwriter.NewWriter(w, 2, 0, 2, ' ', 0)
		f.VisitAll(func(f *flag.Flag) {
			fmt.Fprintf(tw, "\t-%s=%s\t%s\n", f.Name, f.DefValue, f.Usage)
		})
		tw.Flush()
	}
}

func clientLogout(ctx context.Context, cmd Command) error {
	type logout interface {
		Logout(context.Context) error
	}

	if l, ok := cmd.(logout); ok {
		return l.Logout(ctx)
	}

	return nil
}

func Run(args []string) int {
	hw := os.Stderr
	rc := 1
	hwrc := func(arg string) {
		arg = strings.TrimLeft(arg, "-")
		if arg == "h" || arg == "help" {
			hw = os.Stdout
			rc = 0
		}
	}

	var err error

	if len(args) == 0 {
		generalHelp(hw, "")
		return rc
	}

	// Look up real command name in aliases table.
	name, ok := aliases[args[0]]
	if !ok {
		name = args[0]
	}

	cmd, ok := commands[name]
	if !ok {
		hwrc(name)
		generalHelp(hw, name)
		return rc
	}

	fs := flag.NewFlagSet("", flag.ContinueOnError)
	fs.SetOutput(io.Discard)

	ctx := context.Background()

	if id := os.Getenv("GOVC_OPERATION_ID"); id != "" {
		ctx = context.WithValue(ctx, types.ID{}, id)
	}

	cmd.Register(ctx, fs)

	if err = fs.Parse(args[1:]); err != nil {
		goto error
	}

	if err = cmd.Process(ctx); err != nil {
		goto error
	}

	if err = cmd.Run(ctx, fs); err != nil {
		goto error
	}

	if err = clientLogout(ctx, cmd); err != nil {
		goto error
	}

	return 0

error:
	if err == flag.ErrHelp {
		if len(args) == 2 {
			hwrc(args[1])
		}
		commandHelp(hw, args[0], cmd, fs)
	} else {
		if x, ok := err.(interface{ ExitCode() int }); ok {
			// propagate exit code, e.g. from guest.run
			rc = x.ExitCode()
		} else {
			w, ok := cmd.(interface{ WriteError(error) bool })
			if ok {
				ok = w.WriteError(err)
			}
			if !ok {
				fmt.Fprintf(os.Stderr, "%s: %s\n", os.Args[0], err)
			}
		}
	}

	_ = clientLogout(ctx, cmd)

	return rc
}
