package aws

import (
	"fmt"
	"regexp"
	"strings"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/awserr"
	"github.com/aws/aws-sdk-go/service/elb"
	"github.com/hashicorp/terraform/helper/schema"
)

func resourceAwsAppCookieStickinessPolicy() *schema.Resource {
	return &schema.Resource{
		// There is no concept of "updating" an App Stickiness policy in
		// the AWS API.
		Create: resourceAwsAppCookieStickinessPolicyCreate,
		Read:   resourceAwsAppCookieStickinessPolicyRead,
		Delete: resourceAwsAppCookieStickinessPolicyDelete,

		Schema: map[string]*schema.Schema{
			"name": &schema.Schema{
				Type:     schema.TypeString,
				Required: true,
				ForceNew: true,
				ValidateFunc: func(v interface{}, k string) (ws []string, es []error) {
					value := v.(string)
					if !regexp.MustCompile(`^[0-9A-Za-z-]+$`).MatchString(value) {
						es = append(es, fmt.Errorf(
							"only alphanumeric characters and hyphens allowed in %q", k))
					}
					return
				},
			},

			"load_balancer": &schema.Schema{
				Type:     schema.TypeString,
				Required: true,
				ForceNew: true,
			},

			"lb_port": &schema.Schema{
				Type:     schema.TypeInt,
				Required: true,
				ForceNew: true,
			},

			"cookie_name": &schema.Schema{
				Type:     schema.TypeString,
				Required: true,
				ForceNew: true,
			},
		},
	}
}

func resourceAwsAppCookieStickinessPolicyCreate(d *schema.ResourceData, meta interface{}) error {
	elbconn := meta.(*AWSClient).elbconn

	// Provision the AppStickinessPolicy
	acspOpts := &elb.CreateAppCookieStickinessPolicyInput{
		CookieName:       aws.String(d.Get("cookie_name").(string)),
		LoadBalancerName: aws.String(d.Get("load_balancer").(string)),
		PolicyName:       aws.String(d.Get("name").(string)),
	}

	if _, err := elbconn.CreateAppCookieStickinessPolicy(acspOpts); err != nil {
		return fmt.Errorf("Error creating AppCookieStickinessPolicy: %s", err)
	}

	setLoadBalancerOpts := &elb.SetLoadBalancerPoliciesOfListenerInput{
		LoadBalancerName: aws.String(d.Get("load_balancer").(string)),
		LoadBalancerPort: aws.Int64(int64(d.Get("lb_port").(int))),
		PolicyNames:      []*string{aws.String(d.Get("name").(string))},
	}

	if _, err := elbconn.SetLoadBalancerPoliciesOfListener(setLoadBalancerOpts); err != nil {
		return fmt.Errorf("Error setting AppCookieStickinessPolicy: %s", err)
	}

	d.SetId(fmt.Sprintf("%s:%d:%s",
		*acspOpts.LoadBalancerName,
		*setLoadBalancerOpts.LoadBalancerPort,
		*acspOpts.PolicyName))
	return nil
}

func resourceAwsAppCookieStickinessPolicyRead(d *schema.ResourceData, meta interface{}) error {
	elbconn := meta.(*AWSClient).elbconn

	lbName, lbPort, policyName := resourceAwsAppCookieStickinessPolicyParseId(d.Id())

	request := &elb.DescribeLoadBalancerPoliciesInput{
		LoadBalancerName: aws.String(lbName),
		PolicyNames:      []*string{aws.String(policyName)},
	}

	getResp, err := elbconn.DescribeLoadBalancerPolicies(request)
	if err != nil {
		if ec2err, ok := err.(awserr.Error); ok && ec2err.Code() == "PolicyNotFound" {
			// The policy is gone.
			d.SetId("")
			return nil
		}
		return fmt.Errorf("Error retrieving policy: %s", err)
	}

	if len(getResp.PolicyDescriptions) != 1 {
		return fmt.Errorf("Unable to find policy %#v", getResp.PolicyDescriptions)
	}

	// We can get away with this because there's only one attribute, the
	// cookie expiration, in these descriptions.
	policyDesc := getResp.PolicyDescriptions[0]
	cookieAttr := policyDesc.PolicyAttributeDescriptions[0]
	if *cookieAttr.AttributeName != "CookieName" {
		return fmt.Errorf("Unable to find cookie Name.")
	}
	d.Set("cookie_name", cookieAttr.AttributeValue)

	d.Set("name", policyName)
	d.Set("load_balancer", lbName)
	d.Set("lb_port", lbPort)

	return nil
}

func resourceAwsAppCookieStickinessPolicyDelete(d *schema.ResourceData, meta interface{}) error {
	elbconn := meta.(*AWSClient).elbconn

	lbName, _, policyName := resourceAwsAppCookieStickinessPolicyParseId(d.Id())

	// Perversely, if we Set an empty list of PolicyNames, we detach the
	// policies attached to a listener, which is required to delete the
	// policy itself.
	setLoadBalancerOpts := &elb.SetLoadBalancerPoliciesOfListenerInput{
		LoadBalancerName: aws.String(d.Get("load_balancer").(string)),
		LoadBalancerPort: aws.Int64(int64(d.Get("lb_port").(int))),
		PolicyNames:      []*string{},
	}

	if _, err := elbconn.SetLoadBalancerPoliciesOfListener(setLoadBalancerOpts); err != nil {
		return fmt.Errorf("Error removing AppCookieStickinessPolicy: %s", err)
	}

	request := &elb.DeleteLoadBalancerPolicyInput{
		LoadBalancerName: aws.String(lbName),
		PolicyName:       aws.String(policyName),
	}

	if _, err := elbconn.DeleteLoadBalancerPolicy(request); err != nil {
		return fmt.Errorf("Error deleting App stickiness policy %s: %s", d.Id(), err)
	}
	return nil
}

// resourceAwsAppCookieStickinessPolicyParseId takes an ID and parses it into
// it's constituent parts. You need three axes (LB name, policy name, and LB
// port) to create or identify a stickiness policy in AWS's API.
func resourceAwsAppCookieStickinessPolicyParseId(id string) (string, string, string) {
	parts := strings.SplitN(id, ":", 3)
	return parts[0], parts[1], parts[2]
}