package aws

import (
	"crypto/tls"
	"errors"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/awserr"
	"github.com/aws/aws-sdk-go/aws/request"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/acm"
	"github.com/aws/aws-sdk-go/service/apigateway"
	"github.com/aws/aws-sdk-go/service/applicationautoscaling"
	"github.com/aws/aws-sdk-go/service/autoscaling"
	"github.com/aws/aws-sdk-go/service/cloudformation"
	"github.com/aws/aws-sdk-go/service/cloudfront"
	"github.com/aws/aws-sdk-go/service/cloudtrail"
	"github.com/aws/aws-sdk-go/service/cloudwatch"
	"github.com/aws/aws-sdk-go/service/cloudwatchevents"
	"github.com/aws/aws-sdk-go/service/cloudwatchlogs"
	"github.com/aws/aws-sdk-go/service/codebuild"
	"github.com/aws/aws-sdk-go/service/codecommit"
	"github.com/aws/aws-sdk-go/service/codedeploy"
	"github.com/aws/aws-sdk-go/service/codepipeline"
	"github.com/aws/aws-sdk-go/service/configservice"
	"github.com/aws/aws-sdk-go/service/databasemigrationservice"
	"github.com/aws/aws-sdk-go/service/directoryservice"
	"github.com/aws/aws-sdk-go/service/dynamodb"
	"github.com/aws/aws-sdk-go/service/ec2"
	"github.com/aws/aws-sdk-go/service/ecr"
	"github.com/aws/aws-sdk-go/service/ecs"
	"github.com/aws/aws-sdk-go/service/efs"
	"github.com/aws/aws-sdk-go/service/elasticache"
	"github.com/aws/aws-sdk-go/service/elasticbeanstalk"
	elasticsearch "github.com/aws/aws-sdk-go/service/elasticsearchservice"
	"github.com/aws/aws-sdk-go/service/elastictranscoder"
	"github.com/aws/aws-sdk-go/service/elb"
	"github.com/aws/aws-sdk-go/service/elbv2"
	"github.com/aws/aws-sdk-go/service/emr"
	"github.com/aws/aws-sdk-go/service/firehose"
	"github.com/aws/aws-sdk-go/service/glacier"
	"github.com/aws/aws-sdk-go/service/iam"
	"github.com/aws/aws-sdk-go/service/inspector"
	"github.com/aws/aws-sdk-go/service/kinesis"
	"github.com/aws/aws-sdk-go/service/kms"
	"github.com/aws/aws-sdk-go/service/lambda"
	"github.com/aws/aws-sdk-go/service/lightsail"
	"github.com/aws/aws-sdk-go/service/opsworks"
	"github.com/aws/aws-sdk-go/service/rds"
	"github.com/aws/aws-sdk-go/service/redshift"
	"github.com/aws/aws-sdk-go/service/route53"
	"github.com/aws/aws-sdk-go/service/s3"
	"github.com/aws/aws-sdk-go/service/ses"
	"github.com/aws/aws-sdk-go/service/sfn"
	"github.com/aws/aws-sdk-go/service/simpledb"
	"github.com/aws/aws-sdk-go/service/sns"
	"github.com/aws/aws-sdk-go/service/sqs"
	"github.com/aws/aws-sdk-go/service/ssm"
	"github.com/aws/aws-sdk-go/service/sts"
	"github.com/aws/aws-sdk-go/service/waf"
	"github.com/davecgh/go-spew/spew"
	"github.com/hashicorp/errwrap"
	"github.com/hashicorp/go-cleanhttp"
	"github.com/hashicorp/terraform/helper/logging"
	"github.com/hashicorp/terraform/terraform"
)

type Config struct {
	AccessKey     string
	SecretKey     string
	CredsFilename string
	Profile       string
	Token         string
	Region        string
	MaxRetries    int

	AssumeRoleARN         string
	AssumeRoleExternalID  string
	AssumeRoleSessionName string
	AssumeRolePolicy      string

	AllowedAccountIds   []interface{}
	ForbiddenAccountIds []interface{}

	DynamoDBEndpoint string
	KinesisEndpoint  string
	Ec2Endpoint      string
	IamEndpoint      string
	ElbEndpoint      string
	S3Endpoint       string
	Insecure         bool

	SkipCredsValidation     bool
	SkipRegionValidation    bool
	SkipRequestingAccountId bool
	SkipMetadataApiCheck    bool
	S3ForcePathStyle        bool
}

type AWSClient struct {
	cfconn                *cloudformation.CloudFormation
	cloudfrontconn        *cloudfront.CloudFront
	cloudtrailconn        *cloudtrail.CloudTrail
	cloudwatchconn        *cloudwatch.CloudWatch
	cloudwatchlogsconn    *cloudwatchlogs.CloudWatchLogs
	cloudwatcheventsconn  *cloudwatchevents.CloudWatchEvents
	configconn            *configservice.ConfigService
	dmsconn               *databasemigrationservice.DatabaseMigrationService
	dsconn                *directoryservice.DirectoryService
	dynamodbconn          *dynamodb.DynamoDB
	ec2conn               *ec2.EC2
	ecrconn               *ecr.ECR
	ecsconn               *ecs.ECS
	efsconn               *efs.EFS
	elbconn               *elb.ELB
	elbv2conn             *elbv2.ELBV2
	emrconn               *emr.EMR
	esconn                *elasticsearch.ElasticsearchService
	acmconn               *acm.ACM
	apigateway            *apigateway.APIGateway
	appautoscalingconn    *applicationautoscaling.ApplicationAutoScaling
	autoscalingconn       *autoscaling.AutoScaling
	s3conn                *s3.S3
	sesConn               *ses.SES
	simpledbconn          *simpledb.SimpleDB
	sqsconn               *sqs.SQS
	snsconn               *sns.SNS
	stsconn               *sts.STS
	redshiftconn          *redshift.Redshift
	r53conn               *route53.Route53
	partition             string
	accountid             string
	supportedplatforms    []string
	region                string
	rdsconn               *rds.RDS
	iamconn               *iam.IAM
	kinesisconn           *kinesis.Kinesis
	kmsconn               *kms.KMS
	firehoseconn          *firehose.Firehose
	inspectorconn         *inspector.Inspector
	elasticacheconn       *elasticache.ElastiCache
	elasticbeanstalkconn  *elasticbeanstalk.ElasticBeanstalk
	elastictranscoderconn *elastictranscoder.ElasticTranscoder
	lambdaconn            *lambda.Lambda
	lightsailconn         *lightsail.Lightsail
	opsworksconn          *opsworks.OpsWorks
	glacierconn           *glacier.Glacier
	codebuildconn         *codebuild.CodeBuild
	codedeployconn        *codedeploy.CodeDeploy
	codecommitconn        *codecommit.CodeCommit
	codepipelineconn      *codepipeline.CodePipeline
	sfnconn               *sfn.SFN
	ssmconn               *ssm.SSM
	wafconn               *waf.WAF
}

// Client configures and returns a fully initialized AWSClient
func (c *Config) Client() (interface{}, error) {
	// Get the auth and region. This can fail if keys/regions were not
	// specified and we're attempting to use the environment.
	if c.SkipRegionValidation {
		log.Println("[INFO] Skipping region validation")
	} else {
		log.Println("[INFO] Building AWS region structure")
		err := c.ValidateRegion()
		if err != nil {
			return nil, err
		}
	}

	var client AWSClient
	// store AWS region in client struct, for region specific operations such as
	// bucket storage in S3
	client.region = c.Region

	log.Println("[INFO] Building AWS auth structure")
	creds, err := GetCredentials(c)
	if err != nil {
		return nil, err
	}
	// Call Get to check for credential provider. If nothing found, we'll get an
	// error, and we can present it nicely to the user
	cp, err := creds.Get()
	if err != nil {
		if awsErr, ok := err.(awserr.Error); ok && awsErr.Code() == "NoCredentialProviders" {
			return nil, errors.New(`No valid credential sources found for AWS Provider.
  Please see https://terraform.io/docs/providers/aws/index.html for more information on
  providing credentials for the AWS Provider`)
		}

		return nil, fmt.Errorf("Error loading credentials for AWS Provider: %s", err)
	}

	log.Printf("[INFO] AWS Auth provider used: %q", cp.ProviderName)

	awsConfig := &aws.Config{
		Credentials:      creds,
		Region:           aws.String(c.Region),
		MaxRetries:       aws.Int(c.MaxRetries),
		HTTPClient:       cleanhttp.DefaultClient(),
		S3ForcePathStyle: aws.Bool(c.S3ForcePathStyle),
	}

	if logging.IsDebugOrHigher() {
		awsConfig.LogLevel = aws.LogLevel(aws.LogDebugWithHTTPBody)
		awsConfig.Logger = awsLogger{}
	}

	if c.Insecure {
		transport := awsConfig.HTTPClient.Transport.(*http.Transport)
		transport.TLSClientConfig = &tls.Config{
			InsecureSkipVerify: true,
		}
	}

	// Set up base session
	sess, err := session.NewSession(awsConfig)
	if err != nil {
		return nil, errwrap.Wrapf("Error creating AWS session: {{err}}", err)
	}

	sess.Handlers.Build.PushBackNamed(addTerraformVersionToUserAgent)

	if extraDebug := os.Getenv("TERRAFORM_AWS_AUTHFAILURE_DEBUG"); extraDebug != "" {
		sess.Handlers.UnmarshalError.PushFrontNamed(debugAuthFailure)
	}

	// Some services exist only in us-east-1, e.g. because they manage
	// resources that can span across multiple regions, or because
	// signature format v4 requires region to be us-east-1 for global
	// endpoints:
	// http://docs.aws.amazon.com/general/latest/gr/sigv4_changes.html
	usEast1Sess := sess.Copy(&aws.Config{Region: aws.String("us-east-1")})

	// Some services have user-configurable endpoints
	awsEc2Sess := sess.Copy(&aws.Config{Endpoint: aws.String(c.Ec2Endpoint)})
	awsElbSess := sess.Copy(&aws.Config{Endpoint: aws.String(c.ElbEndpoint)})
	awsIamSess := sess.Copy(&aws.Config{Endpoint: aws.String(c.IamEndpoint)})
	awsS3Sess := sess.Copy(&aws.Config{Endpoint: aws.String(c.S3Endpoint)})
	dynamoSess := sess.Copy(&aws.Config{Endpoint: aws.String(c.DynamoDBEndpoint)})
	kinesisSess := sess.Copy(&aws.Config{Endpoint: aws.String(c.KinesisEndpoint)})

	// These two services need to be set up early so we can check on AccountID
	client.iamconn = iam.New(awsIamSess)
	client.stsconn = sts.New(sess)

	if !c.SkipCredsValidation {
		err = c.ValidateCredentials(client.stsconn)
		if err != nil {
			return nil, err
		}
	}

	if !c.SkipRequestingAccountId {
		partition, accountId, err := GetAccountInfo(client.iamconn, client.stsconn, cp.ProviderName)
		if err == nil {
			client.partition = partition
			client.accountid = accountId
		}
	}

	authErr := c.ValidateAccountId(client.accountid)
	if authErr != nil {
		return nil, authErr
	}

	client.ec2conn = ec2.New(awsEc2Sess)

	supportedPlatforms, err := GetSupportedEC2Platforms(client.ec2conn)
	if err != nil {
		// We intentionally fail *silently* because there's a chance
		// user just doesn't have ec2:DescribeAccountAttributes permissions
		log.Printf("[WARN] Unable to get supported EC2 platforms: %s", err)
	} else {
		client.supportedplatforms = supportedPlatforms
	}

	client.acmconn = acm.New(sess)
	client.apigateway = apigateway.New(sess)
	client.appautoscalingconn = applicationautoscaling.New(sess)
	client.autoscalingconn = autoscaling.New(sess)
	client.cfconn = cloudformation.New(sess)
	client.cloudfrontconn = cloudfront.New(sess)
	client.cloudtrailconn = cloudtrail.New(sess)
	client.cloudwatchconn = cloudwatch.New(sess)
	client.cloudwatcheventsconn = cloudwatchevents.New(sess)
	client.cloudwatchlogsconn = cloudwatchlogs.New(sess)
	client.codecommitconn = codecommit.New(sess)
	client.codebuildconn = codebuild.New(sess)
	client.codedeployconn = codedeploy.New(sess)
	client.configconn = configservice.New(sess)
	client.dmsconn = databasemigrationservice.New(sess)
	client.codepipelineconn = codepipeline.New(sess)
	client.dsconn = directoryservice.New(sess)
	client.dynamodbconn = dynamodb.New(dynamoSess)
	client.ecrconn = ecr.New(sess)
	client.ecsconn = ecs.New(sess)
	client.efsconn = efs.New(sess)
	client.elasticacheconn = elasticache.New(sess)
	client.elasticbeanstalkconn = elasticbeanstalk.New(sess)
	client.elastictranscoderconn = elastictranscoder.New(sess)
	client.elbconn = elb.New(awsElbSess)
	client.elbv2conn = elbv2.New(awsElbSess)
	client.emrconn = emr.New(sess)
	client.esconn = elasticsearch.New(sess)
	client.firehoseconn = firehose.New(sess)
	client.inspectorconn = inspector.New(sess)
	client.glacierconn = glacier.New(sess)
	client.kinesisconn = kinesis.New(kinesisSess)
	client.kmsconn = kms.New(sess)
	client.lambdaconn = lambda.New(sess)
	client.lightsailconn = lightsail.New(usEast1Sess)
	client.opsworksconn = opsworks.New(sess)
	client.r53conn = route53.New(usEast1Sess)
	client.rdsconn = rds.New(sess)
	client.redshiftconn = redshift.New(sess)
	client.simpledbconn = simpledb.New(sess)
	client.s3conn = s3.New(awsS3Sess)
	client.sesConn = ses.New(sess)
	client.sfnconn = sfn.New(sess)
	client.snsconn = sns.New(sess)
	client.sqsconn = sqs.New(sess)
	client.ssmconn = ssm.New(sess)
	client.wafconn = waf.New(sess)

	return &client, nil
}

// ValidateRegion returns an error if the configured region is not a
// valid aws region and nil otherwise.
func (c *Config) ValidateRegion() error {
	var regions = []string{
		"ap-northeast-1",
		"ap-northeast-2",
		"ap-south-1",
		"ap-southeast-1",
		"ap-southeast-2",
		"ca-central-1",
		"cn-north-1",
		"eu-central-1",
		"eu-west-1",
		"eu-west-2",
		"sa-east-1",
		"us-east-1",
		"us-east-2",
		"us-gov-west-1",
		"us-west-1",
		"us-west-2",
	}

	for _, valid := range regions {
		if c.Region == valid {
			return nil
		}
	}
	return fmt.Errorf("Not a valid region: %s", c.Region)
}

// Validate credentials early and fail before we do any graph walking.
func (c *Config) ValidateCredentials(stsconn *sts.STS) error {
	_, err := stsconn.GetCallerIdentity(&sts.GetCallerIdentityInput{})
	return err
}

// ValidateAccountId returns a context-specific error if the configured account
// id is explicitly forbidden or not authorised; and nil if it is authorised.
func (c *Config) ValidateAccountId(accountId string) error {
	if c.AllowedAccountIds == nil && c.ForbiddenAccountIds == nil {
		return nil
	}

	log.Println("[INFO] Validating account ID")

	if c.ForbiddenAccountIds != nil {
		for _, id := range c.ForbiddenAccountIds {
			if id == accountId {
				return fmt.Errorf("Forbidden account ID (%s)", id)
			}
		}
	}

	if c.AllowedAccountIds != nil {
		for _, id := range c.AllowedAccountIds {
			if id == accountId {
				return nil
			}
		}
		return fmt.Errorf("Account ID not allowed (%s)", accountId)
	}

	return nil
}

func GetSupportedEC2Platforms(conn *ec2.EC2) ([]string, error) {
	attrName := "supported-platforms"

	input := ec2.DescribeAccountAttributesInput{
		AttributeNames: []*string{aws.String(attrName)},
	}
	attributes, err := conn.DescribeAccountAttributes(&input)
	if err != nil {
		return nil, err
	}

	var platforms []string
	for _, attr := range attributes.AccountAttributes {
		if *attr.AttributeName == attrName {
			for _, v := range attr.AttributeValues {
				platforms = append(platforms, *v.AttributeValue)
			}
			break
		}
	}

	if len(platforms) == 0 {
		return nil, fmt.Errorf("No EC2 platforms detected")
	}

	return platforms, nil
}

// addTerraformVersionToUserAgent is a named handler that will add Terraform's
// version information to requests made by the AWS SDK.
var addTerraformVersionToUserAgent = request.NamedHandler{
	Name: "terraform.TerraformVersionUserAgentHandler",
	Fn: request.MakeAddToUserAgentHandler(
		"APN/1.0 HashiCorp/1.0 Terraform", terraform.VersionString()),
}

var debugAuthFailure = request.NamedHandler{
	Name: "terraform.AuthFailureAdditionalDebugHandler",
	Fn: func(req *request.Request) {
		if isAWSErr(req.Error, "AuthFailure", "AWS was not able to validate the provided access credentials") {
			log.Printf("[INFO] Additional AuthFailure Debugging Context")
			log.Printf("[INFO] Current system UTC time: %s", time.Now().UTC())
			log.Printf("[INFO] Request object: %s", spew.Sdump(req))
		}
	},
}

type awsLogger struct{}

func (l awsLogger) Log(args ...interface{}) {
	tokens := make([]string, 0, len(args))
	for _, arg := range args {
		if token, ok := arg.(string); ok {
			tokens = append(tokens, token)
		}
	}
	log.Printf("[DEBUG] [aws-sdk-go] %s", strings.Join(tokens, " "))
}