// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1

package ldap

import (
	"context"
	"crypto/x509"
	"encoding/json"
	"fmt"
	"net/url"

	"github.com/hashicorp/boundary/internal/errors"
	"github.com/hashicorp/boundary/internal/pagination"
	"github.com/hashicorp/boundary/internal/util"
)

type options struct {
	withName                 string
	withDescription          string
	withFullName             string
	withEmail                string
	withDn                   string
	withStartTls             bool
	withInsecureTls          bool
	withDiscoverDn           bool
	withAnonGroupSearch      bool
	withEnableGroups         bool
	withUseTokenGroups       bool
	withUpnDomain            string
	withUserDn               string
	withUserAttr             string
	withUserFilter           string
	withGroupDn              string
	withGroupAttr            string
	withGroupFilter          string
	withCertificates         []string
	withBindDn               string
	withBindPassword         string
	withClientCertificate    string
	withClientCertificateKey []byte
	withLimit                int
	withUnauthenticatedUser  bool
	withOrderByCreateTime    bool
	ascending                bool
	withOperationalState     AuthMethodState
	withAccountAttributeMap  map[string]AccountToAttribute
	withMemberOfGroups       string
	withUrls                 []string
	withPublicId             string
	withDerefAliases         DerefAliasType
	withMaximumPageSize      uint32
	withStartPageAfterItem   pagination.Item
}

// Option - how options are passed as args
type Option func(*options) error

func getDefaultOptions() options {
	return options{
		withOperationalState: InactiveState,
	}
}

func getOpts(opt ...Option) (options, error) {
	opts := getDefaultOptions()

	for _, o := range opt {
		if err := o(&opts); err != nil {
			return opts, err
		}
	}
	return opts, nil
}

// WithUrls provides optional urls for the auth method.
func WithUrls(ctx context.Context, urls ...*url.URL) Option {
	const op = "ldap.WithUrls"
	return func(o *options) error {
		o.withUrls = make([]string, 0, len(urls))
		for _, u := range urls {
			switch u.Scheme {
			case "ldap", "ldaps":
			default:
				return errors.New(ctx, errors.InvalidParameter, op, fmt.Sprintf("%s scheme in url %q is not either ldap or ldaps", u.Scheme, u.String()))
			}
			o.withUrls = append(o.withUrls, u.String())
		}
		return nil
	}
}

// WithEmail provides an optional email address for the account.
func WithEmail(_ context.Context, email string) Option {
	return func(o *options) error {
		o.withEmail = email
		return nil
	}
}

// WithFullName provides an optional full name for the account.
func WithFullName(_ context.Context, n string) Option {
	return func(o *options) error {
		o.withFullName = n
		return nil
	}
}

// WithDn provides an optional distinguished name
func WithDn(ctx context.Context, dn string) Option {
	const op = "ldap.WithDn"
	return func(o *options) error {
		o.withDn = dn
		return nil
	}
}

// WithName provides an optional name.
func WithName(_ context.Context, n string) Option {
	return func(o *options) error {
		o.withName = n
		return nil
	}
}

// WithDescription provides an optional description.
func WithDescription(_ context.Context, desc string) Option {
	return func(o *options) error {
		o.withDescription = desc
		return nil
	}
}

// WithStartTLS optionally enables a StartTLS command after establishing an
// unencrypted connection.
func WithStartTLS(_ context.Context) Option {
	return func(o *options) error {
		o.withStartTls = true
		return nil
	}
}

// WithEnableGroups optionally enables an authenticated user's groups will be
// found during authentication.
func WithEnableGroups(_ context.Context) Option {
	return func(o *options) error {
		o.withEnableGroups = true
		return nil
	}
}

// WithUseTokenGroups optionally enables the use the Active Directory
// tokenGroups constructed attribute of the user to find the group memberships.
// This will find all security groups including nested ones,
func WithUseTokenGroups(_ context.Context) Option {
	return func(o *options) error {
		o.withUseTokenGroups = true
		return nil
	}
}

// WithInsecureTLS optional specifies to skip LDAP server SSL certificate
// validation - insecure and use with caution
func WithInsecureTLS(_ context.Context) Option {
	return func(o *options) error {
		o.withInsecureTls = true
		return nil
	}
}

// WithDiscoverDn optionally specifies to use anon bind to discover the bind DN
// of a user.
func WithDiscoverDn(_ context.Context) Option {
	return func(o *options) error {
		o.withDiscoverDn = true
		return nil
	}
}

// WithAnonGroupSearch optionally specifies to use anon bind when performing LDAP
// group searches
func WithAnonGroupSearch(_ context.Context) Option {
	return func(o *options) error {
		o.withAnonGroupSearch = true
		return nil
	}
}

// WithUpnDomain optionally specifies the userPrincipalDomain used to construct
// the UPN string for the authenticating user. The constructed UPN will appear
// as [username]@UPNDomain  Example: example.com, which will cause Boundary to
// bind as username@example.com when authenticating the user.
func WithUpnDomain(_ context.Context, domain string) Option {
	return func(o *options) error {
		o.withUpnDomain = domain
		return nil
	}
}

// WithUserDn optionally specifies a user dn used to search for user entries.
func WithUserDn(_ context.Context, dn string) Option {
	return func(o *options) error {
		o.withUserDn = dn
		return nil
	}
}

// WithUserAttr optionally specifies a user attr used to search for user entries.
func WithUserAttr(_ context.Context, attr string) Option {
	return func(o *options) error {
		o.withUserAttr = attr
		return nil
	}
}

// WithUserFilter optionally specifies a user filter used to search for user entries.
func WithUserFilter(_ context.Context, filter string) Option {
	return func(o *options) error {
		o.withUserFilter = filter
		return nil
	}
}

// WithGroupDn optionally specifies a group dn used to search for group entries.
func WithGroupDn(_ context.Context, dn string) Option {
	return func(o *options) error {
		o.withGroupDn = dn
		return nil
	}
}

// WithGroupAttr optionally specifies a group attr used to search for group entries.
func WithGroupAttr(_ context.Context, attr string) Option {
	return func(o *options) error {
		o.withGroupAttr = attr
		return nil
	}
}

// WithGroupFilter optionally specifies a group filter used to search for group entries.
func WithGroupFilter(_ context.Context, filter string) Option {
	return func(o *options) error {
		o.withGroupFilter = filter
		return nil
	}
}

// WithBindCredential optionally specifies a set of optional configuration
// parameters which allow Boundary to bind (aka authenticate) using the
// credentials provided when searching for the user entry used to authenticate
// the end user.
func WithBindCredential(ctx context.Context, dn, password string) Option {
	const op = "ldap.WithBindCredential"
	return func(o *options) error {
		switch {
		case dn == "" && password == "":
			return errors.New(ctx, errors.InvalidParameter, op, "missing both dn and password")
		}
		o.withBindDn = dn
		o.withBindPassword = password
		return nil
	}
}

// WithCertificates provides optional certificates.
func WithCertificates(ctx context.Context, certs ...*x509.Certificate) Option {
	const op = "ldap.WithCertificates"
	return func(o *options) error {
		if len(certs) > 0 {
			o.withCertificates = make([]string, 0, len(certs))
			pem, err := EncodeCertificates(ctx, certs...)
			if err != nil {
				return errors.Wrap(ctx, err, op)
			}
			o.withCertificates = append(o.withCertificates, pem...)
		}
		return nil
	}
}

// WithClientCertificate provides optional configuration fields used for
// specifying a mTLS client cert for LDAP connections.
func WithClientCertificate(ctx context.Context, privKey []byte, cert *x509.Certificate) Option {
	const op = "ldap.WithClientCertificate"
	return func(o *options) error {
		if privKey != nil || cert != nil {
			switch {
			case cert == nil:
				return errors.New(ctx, errors.InvalidParameter, op, "missing certificate")
			case len(privKey) == 0:
				return errors.New(ctx, errors.InvalidParameter, op, "missing private key")
			}
			if _, err := x509.ParsePKCS8PrivateKey(privKey); err != nil {
				return errors.Wrap(ctx, err, op)
			}
			o.withClientCertificateKey = privKey
			pem, err := EncodeCertificates(ctx, cert)
			if err != nil {
				return errors.Wrap(ctx, err, op)
			}
			if len(pem) != 1 {
				return errors.New(ctx, errors.InvalidParameter, op, fmt.Sprintf("too many client certificates (%d)", len(pem)))
			}
			o.withClientCertificate = pem[0]
		}
		return nil
	}
}

// WithLimit provides an option to provide a limit.  Intentionally allowing
// negative integers.   If WithLimit < 0, then unlimited results are returned.
// If WithLimit == 0, then default limits are used for results.
func WithLimit(_ context.Context, l int) Option {
	return func(o *options) error {
		o.withLimit = l
		return nil
	}
}

// WithUnauthenticatedUser provides an option for filtering results for
// an unauthenticated users.
func WithUnauthenticatedUser(_ context.Context, enabled bool) Option {
	return func(o *options) error {
		o.withUnauthenticatedUser = enabled
		return nil
	}
}

// WithOrderByCreateTime provides an option to specify ordering by the
// CreateTime field.
func WithOrderByCreateTime(_ context.Context, ascending bool) Option {
	return func(o *options) error {
		o.withOrderByCreateTime = true
		o.ascending = ascending
		return nil
	}
}

// WithOperationalState provides an option for specifying the auth method's
// operational state
func WithOperationalState(_ context.Context, state AuthMethodState) Option {
	return func(o *options) error {
		o.withOperationalState = state
		return nil
	}
}

// WithAccountAttributeMap provides an option for specifying an Account Attribute map.
func WithAccountAttributeMap(_ context.Context, aam map[string]AccountToAttribute) Option {
	return func(o *options) error {
		o.withAccountAttributeMap = aam
		return nil
	}
}

// WithMemberOfGroups provides an option for specifying a list of group names
func WithMemberOfGroups(ctx context.Context, groupName ...string) Option {
	const op = "ldap.WithMemberOfGroups"
	return func(o *options) error {
		mg, err := json.Marshal(groupName)
		if err != nil {
			return errors.Wrap(ctx, err, op)
		}
		o.withMemberOfGroups = string(mg)
		return nil
	}
}

// WithPublicId provides an option for passing a public id to the operation
func WithPublicId(ctx context.Context, publicId string) Option {
	const op = "ldap.WithPublicId"
	return func(o *options) error {
		o.withPublicId = publicId
		return nil
	}
}

// WithMaximumPageSize provides an option for passing a max page size for group
// searching to the operation
func WithMaximumPageSize(ctx context.Context, max uint32) Option {
	const op = "ldap.WithMaximumPageSize"
	return func(o *options) error {
		o.withMaximumPageSize = max
		return nil
	}
}

// WithDerefAliases provides an option for passing in how dereferencing aliases
// should be handled
func WithDerefAliases(ctx context.Context, derefAlias DerefAliasType) Option {
	const op = "ldap.WithMaximumPageSize"
	return func(o *options) error {
		if err := derefAlias.IsValid(ctx); err != nil {
			return errors.Wrap(ctx, err, op)
		}
		o.withDerefAliases = derefAlias
		return nil
	}
}

type DerefAliasType string

const (
	NeverDerefAliases   DerefAliasType = "NeverDerefAliases"
	DerefInSearching    DerefAliasType = "DerefInSearching"
	DerefFindingBaseObj DerefAliasType = "DerefFindingBaseObj"
	DerefAlways         DerefAliasType = "DerefAlways"
)

func (d DerefAliasType) IsValid(ctx context.Context) error {
	const op = "ldap.(DerefAliasType).IsValid"
	switch d {
	case NeverDerefAliases, DerefInSearching, DerefFindingBaseObj, DerefAlways:
		return nil
	default:
		return errors.New(ctx, errors.InvalidParameter, op, fmt.Sprintf("%q is not a valid ldap dereference alias type", d))
	}
}

// WithStartPageAfterItem is used to paginate over the results.
// The next page will start after the provided item.
func WithStartPageAfterItem(ctx context.Context, item pagination.Item) Option {
	const op = "ldap.WithStartPageAfterItem"
	return func(o *options) error {
		if util.IsNil(item) {
			return errors.New(ctx, errors.InvalidParameter, op, "item cannot be nil")
		}
		o.withStartPageAfterItem = item
		return nil
	}
}