package remote

import (
	"bytes"
	"crypto/md5"
	"crypto/tls"
	"crypto/x509"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"strconv"

	"github.com/gophercloud/gophercloud"
	"github.com/gophercloud/gophercloud/openstack"
	"github.com/gophercloud/gophercloud/openstack/objectstorage/v1/containers"
	"github.com/gophercloud/gophercloud/openstack/objectstorage/v1/objects"
)

const TFSTATE_NAME = "tfstate.tf"

// SwiftClient implements the Client interface for an Openstack Swift server.
type SwiftClient struct {
	client     *gophercloud.ServiceClient
	authurl    string
	cacert     string
	cert       string
	domainid   string
	domainname string
	insecure   bool
	key        string
	password   string
	path       string
	region     string
	tenantid   string
	tenantname string
	userid     string
	username   string
}

func swiftFactory(conf map[string]string) (Client, error) {
	client := &SwiftClient{}

	if err := client.validateConfig(conf); err != nil {
		return nil, err
	}

	return client, nil
}

func (c *SwiftClient) validateConfig(conf map[string]string) (err error) {
	authUrl, ok := conf["auth_url"]
	if !ok {
		authUrl = os.Getenv("OS_AUTH_URL")
		if authUrl == "" {
			return fmt.Errorf("missing 'auth_url' configuration or OS_AUTH_URL environment variable")
		}
	}
	c.authurl = authUrl

	username, ok := conf["user_name"]
	if !ok {
		username = os.Getenv("OS_USERNAME")
	}
	c.username = username

	userID, ok := conf["user_id"]
	if !ok {
		userID = os.Getenv("OS_USER_ID")
	}
	c.userid = userID

	password, ok := conf["password"]
	if !ok {
		password = os.Getenv("OS_PASSWORD")
		if password == "" {
			return fmt.Errorf("missing 'password' configuration or OS_PASSWORD environment variable")
		}
	}
	c.password = password

	region, ok := conf["region_name"]
	if !ok {
		region = os.Getenv("OS_REGION_NAME")
	}
	c.region = region

	tenantID, ok := conf["tenant_id"]
	if !ok {
		tenantID = multiEnv([]string{
			"OS_TENANT_ID",
			"OS_PROJECT_ID",
		})
	}
	c.tenantid = tenantID

	tenantName, ok := conf["tenant_name"]
	if !ok {
		tenantName = multiEnv([]string{
			"OS_TENANT_NAME",
			"OS_PROJECT_NAME",
		})
	}
	c.tenantname = tenantName

	domainID, ok := conf["domain_id"]
	if !ok {
		domainID = multiEnv([]string{
			"OS_USER_DOMAIN_ID",
			"OS_PROJECT_DOMAIN_ID",
			"OS_DOMAIN_ID",
		})
	}
	c.domainid = domainID

	domainName, ok := conf["domain_name"]
	if !ok {
		domainName = multiEnv([]string{
			"OS_USER_DOMAIN_NAME",
			"OS_PROJECT_DOMAIN_NAME",
			"OS_DOMAIN_NAME",
			"DEFAULT_DOMAIN",
		})
	}
	c.domainname = domainName

	path, ok := conf["path"]
	if !ok || path == "" {
		return fmt.Errorf("missing 'path' configuration")
	}
	c.path = path

	c.insecure = false
	raw, ok := conf["insecure"]
	if !ok {
		raw = os.Getenv("OS_INSECURE")
	}
	if raw != "" {
		v, err := strconv.ParseBool(raw)
		if err != nil {
			return fmt.Errorf("'insecure' and 'OS_INSECURE' could not be parsed as bool: %s", err)
		}
		c.insecure = v
	}

	cacertFile, ok := conf["cacert_file"]
	if !ok {
		cacertFile = os.Getenv("OS_CACERT")
	}
	c.cacert = cacertFile

	cert, ok := conf["cert"]
	if !ok {
		cert = os.Getenv("OS_CERT")
	}
	c.cert = cert

	key, ok := conf["key"]
	if !ok {
		key = os.Getenv("OS_KEY")
	}
	c.key = key

	ao := gophercloud.AuthOptions{
		IdentityEndpoint: c.authurl,
		UserID:           c.userid,
		Username:         c.username,
		TenantID:         c.tenantid,
		TenantName:       c.tenantname,
		Password:         c.password,
		DomainID:         c.domainid,
		DomainName:       c.domainname,
	}

	provider, err := openstack.NewClient(ao.IdentityEndpoint)
	if err != nil {
		return err
	}

	config := &tls.Config{}

	if c.cacert != "" {
		caCert, err := ioutil.ReadFile(c.cacert)
		if err != nil {
			return err
		}

		caCertPool := x509.NewCertPool()
		caCertPool.AppendCertsFromPEM(caCert)
		config.RootCAs = caCertPool
	}

	if c.insecure {
		log.Printf("[DEBUG] Insecure mode set")
		config.InsecureSkipVerify = true
	}

	if c.cert != "" && c.key != "" {
		cert, err := tls.LoadX509KeyPair(c.cert, c.key)
		if err != nil {
			return err
		}

		config.Certificates = []tls.Certificate{cert}
		config.BuildNameToCertificate()
	}

	transport := &http.Transport{Proxy: http.ProxyFromEnvironment, TLSClientConfig: config}
	provider.HTTPClient.Transport = transport

	err = openstack.Authenticate(provider, ao)
	if err != nil {
		return err
	}

	c.client, err = openstack.NewObjectStorageV1(provider, gophercloud.EndpointOpts{
		Region: c.region,
	})

	return err
}

func (c *SwiftClient) Get() (*Payload, error) {
	result := objects.Download(c.client, c.path, TFSTATE_NAME, nil)

	// Extract any errors from result
	_, err := result.Extract()

	// 404 response is to be expected if the object doesn't already exist!
	if _, ok := err.(gophercloud.ErrDefault404); ok {
		log.Printf("[DEBUG] Container doesn't exist to download.")
		return nil, nil
	}

	bytes, err := result.ExtractContent()
	if err != nil {
		return nil, err
	}

	hash := md5.Sum(bytes)
	payload := &Payload{
		Data: bytes,
		MD5:  hash[:md5.Size],
	}

	return payload, nil
}

func (c *SwiftClient) Put(data []byte) error {
	if err := c.ensureContainerExists(); err != nil {
		return err
	}

	reader := bytes.NewReader(data)
	createOpts := objects.CreateOpts{
		Content: reader,
	}
	result := objects.Create(c.client, c.path, TFSTATE_NAME, createOpts)

	return result.Err
}

func (c *SwiftClient) Delete() error {
	result := objects.Delete(c.client, c.path, TFSTATE_NAME, nil)
	return result.Err
}

func (c *SwiftClient) ensureContainerExists() error {
	result := containers.Create(c.client, c.path, nil)
	if result.Err != nil {
		return result.Err
	}

	return nil
}

func multiEnv(ks []string) string {
	for _, k := range ks {
		if v := os.Getenv(k); v != "" {
			return v
		}
	}
	return ""
}