package tpm

import (
	"net/http"

	"github.com/google/go-attestation/attest"
)

type config struct {
	emulated       bool
	commandChannel attest.CommandChannelTPM20
	seed           int64

	cacerts []byte
	header  http.Header
}

// Option is a generic option for TPM configuration
type Option func(c *config) error

// Emulated sets an emulated device in place of a real native TPM device.
// Note, the emulated device is embedded and it is unsafe.
// Should just be used for testing.
var Emulated Option = func(c *config) error {
	c.emulated = true
	return nil
}

// WithCAs sets the root CAs for the request
func WithCAs(ca []byte) Option {
	return func(c *config) error {
		c.cacerts = ca
		return nil
	}
}

// WithHeader sets a specific header for the request
func WithHeader(header http.Header) Option {
	return func(c *config) error {
		c.header = header
		return nil
	}
}

// WithSeed sets a permanent seed. Used with TPM emulated device.
func WithSeed(s int64) Option {
	return func(c *config) error {
		c.seed = s
		return nil
	}
}

// WithCommandChannel overrides the TPM command channel
func WithCommandChannel(cc attest.CommandChannelTPM20) Option {
	return func(c *config) error {
		c.commandChannel = cc
		return nil
	}
}

func (c *config) apply(opts ...Option) error {
	for _, o := range opts {
		if err := o(c); err != nil {
			return err
		}
	}

	return nil
}