package aws

import (
	"fmt"
	"log"
	"time"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/awserr"
	"github.com/aws/aws-sdk-go/aws/awsutil"
	"github.com/aws/aws-sdk-go/service/ec2"
	"github.com/hashicorp/terraform/helper/resource"
	"github.com/hashicorp/terraform/helper/schema"
)

func resourceAwsSpotInstanceRequest() *schema.Resource {
	return &schema.Resource{
		Create: resourceAwsSpotInstanceRequestCreate,
		Read:   resourceAwsSpotInstanceRequestRead,
		Delete: resourceAwsSpotInstanceRequestDelete,
		Update: resourceAwsSpotInstanceRequestUpdate,

		Schema: func() map[string]*schema.Schema {
			// The Spot Instance Request Schema is based on the AWS Instance schema.
			s := resourceAwsInstance().Schema

			// Everything on a spot instance is ForceNew except tags
			for k, v := range s {
				if k == "tags" {
					continue
				}
				v.ForceNew = true
			}

			s["spot_price"] = &schema.Schema{
				Type:     schema.TypeString,
				Required: true,
				ForceNew: true,
			}
			s["wait_for_fulfillment"] = &schema.Schema{
				Type:     schema.TypeBool,
				Optional: true,
				Default:  false,
			}
			s["spot_bid_status"] = &schema.Schema{
				Type:     schema.TypeString,
				Computed: true,
			}
			s["spot_request_state"] = &schema.Schema{
				Type:     schema.TypeString,
				Computed: true,
			}
			s["spot_instance_id"] = &schema.Schema{
				Type:     schema.TypeString,
				Computed: true,
			}

			return s
		}(),
	}
}

func resourceAwsSpotInstanceRequestCreate(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*AWSClient).ec2conn

	instanceOpts, err := buildAwsInstanceOpts(d, meta)
	if err != nil {
		return err
	}

	spotOpts := &ec2.RequestSpotInstancesInput{
		SpotPrice: aws.String(d.Get("spot_price").(string)),

		// We always set the type to "persistent", since the imperative-like
		// behavior of "one-time" does not map well to TF's declarative domain.
		Type: aws.String("persistent"),

		// Though the AWS API supports creating spot instance requests for multiple
		// instances, for TF purposes we fix this to one instance per request.
		// Users can get equivalent behavior out of TF's "count" meta-parameter.
		InstanceCount: aws.Long(1),

		LaunchSpecification: &ec2.RequestSpotLaunchSpecification{
			BlockDeviceMappings: instanceOpts.BlockDeviceMappings,
			EBSOptimized:        instanceOpts.EBSOptimized,
			Monitoring:          instanceOpts.Monitoring,
			IAMInstanceProfile:  instanceOpts.IAMInstanceProfile,
			ImageID:             instanceOpts.ImageID,
			InstanceType:        instanceOpts.InstanceType,
			Placement:           instanceOpts.SpotPlacement,
			SecurityGroupIDs:    instanceOpts.SecurityGroupIDs,
			SecurityGroups:      instanceOpts.SecurityGroups,
			UserData:            instanceOpts.UserData64,
		},
	}

	// Make the spot instance request
	resp, err := conn.RequestSpotInstances(spotOpts)
	if err != nil {
		return fmt.Errorf("Error requesting spot instances: %s", err)
	}
	if len(resp.SpotInstanceRequests) != 1 {
		return fmt.Errorf(
			"Expected response with length 1, got: %s", awsutil.StringValue(resp))
	}

	sir := *resp.SpotInstanceRequests[0]
	d.SetId(*sir.SpotInstanceRequestID)

	if d.Get("wait_for_fulfillment").(bool) {
		spotStateConf := &resource.StateChangeConf{
			// http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-bid-status.html
			Pending:    []string{"start", "pending-evaluation", "pending-fulfillment"},
			Target:     "fulfilled",
			Refresh:    SpotInstanceStateRefreshFunc(conn, sir),
			Timeout:    10 * time.Minute,
			Delay:      10 * time.Second,
			MinTimeout: 3 * time.Second,
		}

		log.Printf("[DEBUG] waiting for spot bid to resolve... this may take several minutes.")
		_, err = spotStateConf.WaitForState()

		if err != nil {
			return fmt.Errorf("Error while waiting for spot request (%s) to resolve: %s", awsutil.StringValue(sir), err)
		}
	}

	return resourceAwsSpotInstanceRequestUpdate(d, meta)
}

// Update spot state, etc
func resourceAwsSpotInstanceRequestRead(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*AWSClient).ec2conn

	req := &ec2.DescribeSpotInstanceRequestsInput{
		SpotInstanceRequestIDs: []*string{aws.String(d.Id())},
	}
	resp, err := conn.DescribeSpotInstanceRequests(req)

	if err != nil {
		// If the spot request was not found, return nil so that we can show
		// that it is gone.
		if ec2err, ok := err.(awserr.Error); ok && ec2err.Code() == "InvalidSpotInstanceRequestID.NotFound" {
			d.SetId("")
			return nil
		}

		// Some other error, report it
		return err
	}

	// If nothing was found, then return no state
	if len(resp.SpotInstanceRequests) == 0 {
		d.SetId("")
		return nil
	}

	request := resp.SpotInstanceRequests[0]

	// if the request is cancelled, then it is gone
	if *request.State == "canceled" {
		d.SetId("")
		return nil
	}

	d.Set("spot_bid_status", *request.Status.Code)
	d.Set("spot_instance_id", *request.InstanceID)
	d.Set("spot_request_state", *request.State)
	d.Set("tags", tagsToMap(request.Tags))

	return nil
}

func resourceAwsSpotInstanceRequestUpdate(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*AWSClient).ec2conn

	d.Partial(true)
	if err := setTags(conn, d); err != nil {
		return err
	} else {
		d.SetPartial("tags")
	}

	d.Partial(false)

	return resourceAwsInstanceRead(d, meta)
}

func resourceAwsSpotInstanceRequestDelete(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*AWSClient).ec2conn

	log.Printf("[INFO] Cancelling spot request: %s", d.Id())
	_, err := conn.CancelSpotInstanceRequests(&ec2.CancelSpotInstanceRequestsInput{
		SpotInstanceRequestIDs: []*string{aws.String(d.Id())},
	})

	if err != nil {
		return fmt.Errorf("Error cancelling spot request (%s): %s", d.Id(), err)
	}

	if instanceId := d.Get("spot_instance_id").(string); instanceId != "" {
		log.Printf("[INFO] Terminating instance: %s", instanceId)
		if err := awsTerminateInstance(conn, instanceId); err != nil {
			return fmt.Errorf("Error terminating spot instance: %s", err)
		}
	}

	return nil
}

// SpotInstanceStateRefreshFunc returns a resource.StateRefreshFunc that is used to watch
// an EC2 spot instance request
func SpotInstanceStateRefreshFunc(
	conn *ec2.EC2, sir ec2.SpotInstanceRequest) resource.StateRefreshFunc {

	return func() (interface{}, string, error) {
		resp, err := conn.DescribeSpotInstanceRequests(&ec2.DescribeSpotInstanceRequestsInput{
			SpotInstanceRequestIDs: []*string{sir.SpotInstanceRequestID},
		})

		if err != nil {
			if ec2err, ok := err.(awserr.Error); ok && ec2err.Code() == "InvalidSpotInstanceRequestID.NotFound" {
				// Set this to nil as if we didn't find anything.
				resp = nil
			} else {
				log.Printf("Error on StateRefresh: %s", err)
				return nil, "", err
			}
		}

		if resp == nil || len(resp.SpotInstanceRequests) == 0 {
			// Sometimes AWS just has consistency issues and doesn't see
			// our request yet. Return an empty state.
			return nil, "", nil
		}

		req := resp.SpotInstanceRequests[0]
		return req, *req.Status.Code, nil
	}
}