package aws

import (
	"fmt"
	"log"
	"regexp"
	"time"

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

func resourceAwsRedshiftSubnetGroup() *schema.Resource {
	return &schema.Resource{
		Create: resourceAwsRedshiftSubnetGroupCreate,
		Read:   resourceAwsRedshiftSubnetGroupRead,
		Update: resourceAwsRedshiftSubnetGroupUpdate,
		Delete: resourceAwsRedshiftSubnetGroupDelete,
		Importer: &schema.ResourceImporter{
			State: schema.ImportStatePassthrough,
		},

		Schema: map[string]*schema.Schema{
			"name": {
				Type:         schema.TypeString,
				ForceNew:     true,
				Required:     true,
				ValidateFunc: validateRedshiftSubnetGroupName,
			},

			"description": {
				Type:     schema.TypeString,
				Optional: true,
				Default:  "Managed by Terraform",
			},

			"subnet_ids": {
				Type:     schema.TypeSet,
				Required: true,
				Elem:     &schema.Schema{Type: schema.TypeString},
				Set:      schema.HashString,
			},

			"tags": tagsSchema(),
		},
	}
}

func resourceAwsRedshiftSubnetGroupCreate(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*AWSClient).redshiftconn

	subnetIdsSet := d.Get("subnet_ids").(*schema.Set)
	subnetIds := make([]*string, subnetIdsSet.Len())
	for i, subnetId := range subnetIdsSet.List() {
		subnetIds[i] = aws.String(subnetId.(string))
	}
	tags := tagsFromMapRedshift(d.Get("tags").(map[string]interface{}))

	createOpts := redshift.CreateClusterSubnetGroupInput{
		ClusterSubnetGroupName: aws.String(d.Get("name").(string)),
		Description:            aws.String(d.Get("description").(string)),
		SubnetIds:              subnetIds,
		Tags:                   tags,
	}

	log.Printf("[DEBUG] Create Redshift Subnet Group: %#v", createOpts)
	_, err := conn.CreateClusterSubnetGroup(&createOpts)
	if err != nil {
		return fmt.Errorf("Error creating Redshift Subnet Group: %s", err)
	}

	d.SetId(*createOpts.ClusterSubnetGroupName)
	log.Printf("[INFO] Redshift Subnet Group ID: %s", d.Id())
	return resourceAwsRedshiftSubnetGroupRead(d, meta)
}

func resourceAwsRedshiftSubnetGroupRead(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*AWSClient).redshiftconn

	describeOpts := redshift.DescribeClusterSubnetGroupsInput{
		ClusterSubnetGroupName: aws.String(d.Id()),
	}

	describeResp, err := conn.DescribeClusterSubnetGroups(&describeOpts)
	if err != nil {
		if ec2err, ok := err.(awserr.Error); ok && ec2err.Code() == "ClusterSubnetGroupNotFoundFault" {
			log.Printf("[INFO] Redshift Subnet Group: %s was not found", d.Id())
			d.SetId("")
			return nil
		}
		return err
	}

	if len(describeResp.ClusterSubnetGroups) == 0 {
		return fmt.Errorf("Unable to find Redshift Subnet Group: %#v", describeResp.ClusterSubnetGroups)
	}

	d.Set("name", d.Id())
	d.Set("description", describeResp.ClusterSubnetGroups[0].Description)
	d.Set("subnet_ids", subnetIdsToSlice(describeResp.ClusterSubnetGroups[0].Subnets))
	if err := d.Set("tags", tagsToMapRedshift(describeResp.ClusterSubnetGroups[0].Tags)); err != nil {
		return fmt.Errorf("[DEBUG] Error setting Redshift Subnet Group Tags: %#v", err)
	}

	return nil
}

func resourceAwsRedshiftSubnetGroupUpdate(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*AWSClient).redshiftconn

	arn, tagErr := buildRedshiftSubnetGroupARN(d.Id(), meta.(*AWSClient).partition, meta.(*AWSClient).accountid, meta.(*AWSClient).region)
	if tagErr != nil {
		return fmt.Errorf("Error building ARN for Redshift Subnet Group, not updating Tags for Subnet Group %s", d.Id())
	} else {
		if tagErr := setTagsRedshift(conn, d, arn); tagErr != nil {
			return tagErr
		}
	}

	if d.HasChange("subnet_ids") || d.HasChange("description") {
		_, n := d.GetChange("subnet_ids")
		if n == nil {
			n = new(schema.Set)
		}
		ns := n.(*schema.Set)

		var sIds []*string
		for _, s := range ns.List() {
			sIds = append(sIds, aws.String(s.(string)))
		}

		_, err := conn.ModifyClusterSubnetGroup(&redshift.ModifyClusterSubnetGroupInput{
			ClusterSubnetGroupName: aws.String(d.Id()),
			Description:            aws.String(d.Get("description").(string)),
			SubnetIds:              sIds,
		})

		if err != nil {
			return err
		}
	}

	return nil
}

func resourceAwsRedshiftSubnetGroupDelete(d *schema.ResourceData, meta interface{}) error {
	stateConf := &resource.StateChangeConf{
		Pending:    []string{"pending"},
		Target:     []string{"destroyed"},
		Refresh:    resourceAwsRedshiftSubnetGroupDeleteRefreshFunc(d, meta),
		Timeout:    3 * time.Minute,
		MinTimeout: 1 * time.Second,
	}
	_, err := stateConf.WaitForState()
	return err
}

func resourceAwsRedshiftSubnetGroupDeleteRefreshFunc(d *schema.ResourceData, meta interface{}) resource.StateRefreshFunc {
	conn := meta.(*AWSClient).redshiftconn

	return func() (interface{}, string, error) {

		deleteOpts := redshift.DeleteClusterSubnetGroupInput{
			ClusterSubnetGroupName: aws.String(d.Id()),
		}

		if _, err := conn.DeleteClusterSubnetGroup(&deleteOpts); err != nil {
			redshiftErr, ok := err.(awserr.Error)
			if !ok {
				return d, "error", err
			}

			if redshiftErr.Code() != "ClusterSubnetGroupNotFoundFault" {
				return d, "error", err
			}
		}

		return d, "destroyed", nil
	}
}

func subnetIdsToSlice(subnetIds []*redshift.Subnet) []string {
	subnetsSlice := make([]string, 0, len(subnetIds))
	for _, s := range subnetIds {
		subnetsSlice = append(subnetsSlice, *s.SubnetIdentifier)
	}
	return subnetsSlice
}

func validateRedshiftSubnetGroupName(v interface{}, k string) (ws []string, errors []error) {
	value := v.(string)
	if !regexp.MustCompile(`^[0-9a-z-]+$`).MatchString(value) {
		errors = append(errors, fmt.Errorf(
			"only lowercase alphanumeric characters and hyphens allowed in %q", k))
	}
	if len(value) > 255 {
		errors = append(errors, fmt.Errorf(
			"%q cannot be longer than 255 characters", k))
	}
	if regexp.MustCompile(`(?i)^default$`).MatchString(value) {
		errors = append(errors, fmt.Errorf(
			"%q is not allowed as %q", "Default", k))
	}
	return
}

func buildRedshiftSubnetGroupARN(identifier, partition, accountid, region string) (string, error) {
	if partition == "" {
		return "", fmt.Errorf("Unable to construct Subnet Group ARN because of missing AWS partition")
	}
	if accountid == "" {
		return "", fmt.Errorf("Unable to construct Subnet Group ARN because of missing AWS Account ID")
	}
	arn := fmt.Sprintf("arn:%s:redshift:%s:%s:subnetgroup:%s", partition, region, accountid, identifier)
	return arn, nil

}