package ssh

import (
	"fmt"
	"net"
	"strconv"
	"strings"

	"github.com/hashicorp/vault/logical"
	"github.com/hashicorp/vault/logical/framework"
)

const KeyTypeOTP = "otp"
const KeyTypeDynamic = "dynamic"
const KeyBitsRSA = "2048"

func pathRoles(b *backend) *framework.Path {
	return &framework.Path{
		Pattern: "roles/(?P<name>[-\\w]+)",
		Fields: map[string]*framework.FieldSchema{
			"name": &framework.FieldSchema{
				Type:        framework.TypeString,
				Description: "Name of the role",
			},
			"key": &framework.FieldSchema{
				Type:        framework.TypeString,
				Description: "Named key in Vault",
			},
			"admin_user": &framework.FieldSchema{
				Type:        framework.TypeString,
				Description: "Admin user at target address",
			},
			"default_user": &framework.FieldSchema{
				Type:        framework.TypeString,
				Description: "Default user to whom the dynamic key is installed",
			},
			"cidr": &framework.FieldSchema{
				Type:        framework.TypeString,
				Description: "CIDR blocks and IP addresses",
			},
			"port": &framework.FieldSchema{
				Type:        framework.TypeString,
				Description: "Port number for SSH connection",
			},
			"key_type": &framework.FieldSchema{
				Type:        framework.TypeString,
				Description: "one-time-password or dynamic-key",
			},
			"key_bits": &framework.FieldSchema{
				Type:        framework.TypeString,
				Description: "number of bits in keys",
			},
		},

		Callbacks: map[logical.Operation]framework.OperationFunc{
			logical.ReadOperation:   b.pathRoleRead,
			logical.WriteOperation:  b.pathRoleWrite,
			logical.DeleteOperation: b.pathRoleDelete,
		},

		HelpSynopsis:    pathRoleHelpSyn,
		HelpDescription: pathRoleHelpDesc,
	}
}

func (b *backend) pathRoleWrite(req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
	roleName := d.Get("name").(string)
	if roleName == "" {
		return logical.ErrorResponse("Missing role name"), nil
	}

	cidr := d.Get("cidr").(string)
	if cidr == "" {
		return logical.ErrorResponse("Missing cidr blocks"), nil
	}
	for _, item := range strings.Split(cidr, ",") {
		_, _, err := net.ParseCIDR(item)
		if err != nil {
			return logical.ErrorResponse(fmt.Sprintf("Invalid cidr entry '%s'", item)), nil
		}
	}

	port := d.Get("port").(string)
	if port == "" {
		port = "22"
	}

	keyType := d.Get("key_type").(string)
	if keyType == "" {
		return logical.ErrorResponse("Missing key type"), nil
	}
	keyType = strings.ToLower(keyType)

	var entry *logical.StorageEntry
	var err error
	if keyType == KeyTypeOTP {
		adminUser := d.Get("admin_user").(string)
		if adminUser != "" {
			return logical.ErrorResponse("Admin user not required for OTP type"), nil
		}

		defaultUser := d.Get("default_user").(string)
		if defaultUser == "" {
			return logical.ErrorResponse("Missing default user"), nil
		}

		entry, err = logical.StorageEntryJSON(fmt.Sprintf("policy/%s", roleName), sshRole{
			DefaultUser: defaultUser,
			CIDR:        cidr,
			KeyType:     KeyTypeOTP,
			Port:        port,
		})
	} else if keyType == KeyTypeDynamic {
		keyName := d.Get("key").(string)
		if keyName == "" {
			return logical.ErrorResponse("Missing key name"), nil
		}
		keyEntry, err := req.Storage.Get(fmt.Sprintf("keys/%s", keyName))
		if err != nil || keyEntry == nil {
			return logical.ErrorResponse(fmt.Sprintf("Invalid 'key': '%s'", keyName)), nil
		}

		adminUser := d.Get("admin_user").(string)
		if adminUser == "" {
			return logical.ErrorResponse("Missing admin username"), nil
		}

		defaultUser := d.Get("default_user").(string)
		if defaultUser == "" {
			defaultUser = adminUser
		}

		keyBits := d.Get("key_bits").(string)
		if keyBits != "" {
			_, err := strconv.Atoi(keyBits)
			if err != nil {
				return logical.ErrorResponse("Key bits should be an integer"), nil
			}
		}
		if keyBits == "" {
			keyBits = KeyBitsRSA
		}

		entry, err = logical.StorageEntryJSON(fmt.Sprintf("policy/%s", roleName), sshRole{
			KeyName:     keyName,
			AdminUser:   adminUser,
			DefaultUser: defaultUser,
			CIDR:        cidr,
			Port:        port,
			KeyType:     KeyTypeDynamic,
			KeyBits:     keyBits,
		})
	} else {
		return logical.ErrorResponse("Invalid key type"), nil
	}

	if err != nil {
		return nil, err
	}

	if err := req.Storage.Put(entry); err != nil {
		return nil, err
	}
	return nil, nil
}

func (b *backend) pathRoleRead(req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
	roleName := d.Get("name").(string)
	roleEntry, err := req.Storage.Get(fmt.Sprintf("policy/%s", roleName))
	if err != nil {
		return nil, err
	}
	if roleEntry == nil {
		return nil, nil
	}

	var role sshRole
	if err := roleEntry.DecodeJSON(&role); err != nil {
		return nil, err
	}

	if role.KeyType == KeyTypeOTP {
		return &logical.Response{
			Data: map[string]interface{}{
				"default_user": role.DefaultUser,
				"cidr":         role.CIDR,
				"port":         role.Port,
				"key_type":     role.KeyType,
			},
		}, nil
	} else {
		return &logical.Response{
			Data: map[string]interface{}{
				"key":          role.KeyName,
				"admin_user":   role.AdminUser,
				"default_user": role.DefaultUser,
				"cidr":         role.CIDR,
				"port":         role.Port,
				"key_type":     role.KeyType,
			},
		}, nil
	}
}

func (b *backend) pathRoleDelete(req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
	roleName := d.Get("name").(string)
	err := req.Storage.Delete(fmt.Sprintf("policy/%s", roleName))
	if err != nil {
		return nil, err
	}
	return nil, nil
}

type sshRole struct {
	KeyType     string `mapstructure:"key_type" json:"key_type"`
	KeyName     string `mapstructure:"key" json:"key"`
	KeyBits     string `mapstructure:"key_bits" json:"key_bits"`
	AdminUser   string `mapstructure:"admin_user" json:"admin_user"`
	DefaultUser string `mapstructure:"default_user" json:"default_user"`
	CIDR        string `mapstructure:"cidr" json:"cidr"`
	Port        string `mapstructure:"port" json:"port"`
}

const pathRoleHelpSyn = `
Manage the 'roles' that can be created with this backend.
`

const pathRoleHelpDesc = `
This path allows you to manage the roles that are used to create
keys. These roles will be having privileged access to all
the hosts mentioned by CIDR blocks. For example, if the backend
is mounted at "ssh" and the role is created at "ssh/roles/web",
then a user could request for a new key at "ssh/creds/web" for the
supplied username and IP address.

The 'cidr' field takes comma seperated CIDR blocks. The 'admin_user'
should have root access in all the hosts represented by the 'cidr'
field. When the user requests key for an IP, the key will be installed
for the user mentioned by 'default_user' field. The 'key' field takes
a named key which can be configured by 'ssh/keys/' endpoint.

Role Options:

  -key_type		This can be either 'otp' or 'dynamic'. 'otp' key requires
  			agent to be installed in target machine. Required field for
			both types.

  -key			Name of the key registered using 'keys/' endpoint. Required
  			field for 'dynamic' type. Not applicable for 'otp' type.

  -admin_user		Username at the target which is having root privileges. This
  			username will be used to install keys for other unprivileged
			users. Required field for 'dynamic' type. Not applicable for
			'otp' type.

  -default_user		When keys are created using '/creds' endpoint with only the
  			IP address, by default, this username is used to create the
			credentials. Required for 'otp' type. Optional for 'dynamic' type.

  -cidr			CIDR block for which is role is applicable for. Required field
  			for both types.

  -port			Port number for SSH connections. Default is '22'. Optional for
  			both types.

  -key_bits		Length of RSa dynamic key in bits. Optional for 'dynamic' type.
  			Not applicable for 'otp' type.
`