// Copyright 2016 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
	"strconv"
	"strings"

	"v.io/x/lib/cmdline"
)

// TODO(youngseokyoon): implement the following sub-commands.
//  - remove:    remove members from an existing group
//  - rename:    rename a group
//  - delete:    delete a group
//  - list:      list all the groups and their members
//  - clear-all: delete all the existing device groups

// TODO(youngseokyoon): use the groups for filtering devices.

var cmdMadbGroup = &cmdline.Command{
	Children:         []*cmdline.Command{cmdMadbGroupAdd},
	Name:             "group",
	DontInheritFlags: true,
	Short:            "Manage device groups",
	Long: `
Manages device groups, each of which can have one or more device members. The
device groups can be used for specifying the target devices of other madb
commands.
`,
}

var cmdMadbGroupAdd = &cmdline.Command{
	Runner: subCommandRunnerWithFilepath{runMadbGroupAdd, getDefaultConfigFilePath},
	Name:   "add",
	Short:  "Add devices to a device group",
	Long: `
Adds devices to a device group. This command also creates the group, if the
group does not exist yet. The device group can be used when specifying devices
in any madb commands.

When creating a new device group with this command, the provided name must not
conflict with an existing device nickname (see: madb help name set).

A group can contain another device group, in which case all the members of the
other group will also be considered as members of the current group.
`,
	ArgsName: "<group_name> <member1> [<member2> ...]",
	ArgsLong: `
<group_name> is an alpha-numeric string with no special characters or spaces.
This name must not be an existing device nickname.

<member> is a member specifier, which can be one of device serial, qualifier,
device index (e.g., '@1', '@2'), device nickname, or another device group.
`,
}

func runMadbGroupAdd(env *cmdline.Env, args []string, filename string) error {
	// Check if the arguments are valid.
	if len(args) < 2 {
		return env.UsageErrorf("There must be at least two arguments.")
	}

	groupName := args[0]
	if !isValidName(groupName) {
		return fmt.Errorf("Not a valid group name: %q", groupName)
	}

	cfg, err := readConfig(filename)
	if err != nil {
		return err
	}
	if isDeviceNickname(groupName, cfg) {
		return fmt.Errorf("The group name %q conflicts with a device nickname.", groupName)
	}

	members := removeDuplicates(args[1:])
	for _, member := range members {
		if err := isValidMember(member, cfg); err != nil {
			return fmt.Errorf("Invalid member %q: %v", member, err)
		}
	}

	oldMembers, ok := cfg.Groups[groupName]
	if !ok {
		oldMembers = []string{}
	}

	cfg.Groups[groupName] = removeDuplicates(append(oldMembers, members...))
	return writeConfig(cfg, filename)
}

// isValidMember takes a member string given as an argument, and returns nil
// when the member string is valid. Otherwise, an error is returned inicating
// the reason why the given member string is not valid.
// TODO(youngseokyoon): reuse this function in madb.go.
func isValidMember(member string, cfg *config) error {
	if strings.HasPrefix(member, "@") {
		index, err := strconv.Atoi(member[1:])
		if err != nil || index <= 0 {
			return fmt.Errorf("Invalid device specifier %q. '@' sign must be followed by a numeric device index starting from 1.", member)
		}
		return nil
	} else if !isValidSerial(member) && !isValidName(member) {
		return fmt.Errorf("Invalid device specifier %q. Not a valid serial or a nickname.", member)
	}

	return nil
}

// removeDuplicates takes a string slice and removes all the duplicates.
func removeDuplicates(s []string) []string {
	result := make([]string, 0, len(s))

	used := map[string]bool{}
	for _, elem := range s {
		if !used[elem] {
			result = append(result, elem)
			used[elem] = true
		}
	}

	return result
}