package aws

import (
	"fmt"
	"log"

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

func dataSourceAwsInstance() *schema.Resource {
	return &schema.Resource{
		Read: dataSourceAwsInstanceRead,

		Schema: map[string]*schema.Schema{
			"filter":        dataSourceFiltersSchema(),
			"tags":          dataSourceTagsSchema(),
			"instance_tags": tagsSchemaComputed(),
			"instance_id": {
				Type:     schema.TypeString,
				Optional: true,
				ForceNew: true,
			},
			"ami": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"instance_type": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"instance_state": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"availability_zone": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"tenancy": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"key_name": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"public_dns": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"public_ip": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"private_dns": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"private_ip": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"iam_instance_profile": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"subnet_id": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"network_interface_id": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"associate_public_ip_address": {
				Type:     schema.TypeBool,
				Computed: true,
			},
			"ebs_optimized": {
				Type:     schema.TypeBool,
				Computed: true,
			},
			"source_dest_check": {
				Type:     schema.TypeBool,
				Computed: true,
			},
			"monitoring": {
				Type:     schema.TypeBool,
				Computed: true,
			},
			"user_data": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"security_groups": {
				Type:     schema.TypeSet,
				Computed: true,
				Elem: &schema.Schema{
					Type: schema.TypeString,
				},
			},
			"vpc_security_group_ids": {
				Type:     schema.TypeSet,
				Computed: true,
				Elem: &schema.Schema{
					Type: schema.TypeString,
				},
			},
			"ephemeral_block_device": {
				Type:     schema.TypeSet,
				Computed: true,
				Elem: &schema.Resource{
					Schema: map[string]*schema.Schema{
						"device_name": {
							Type:     schema.TypeString,
							Required: true,
						},

						"virtual_name": {
							Type:     schema.TypeString,
							Optional: true,
						},

						"no_device": {
							Type:     schema.TypeBool,
							Optional: true,
						},
					},
				},
			},
			"ebs_block_device": {
				Type:     schema.TypeSet,
				Computed: true,
				Elem: &schema.Resource{
					Schema: map[string]*schema.Schema{
						"delete_on_termination": {
							Type:     schema.TypeBool,
							Computed: true,
						},

						"device_name": {
							Type:     schema.TypeString,
							Computed: true,
						},

						"encrypted": {
							Type:     schema.TypeBool,
							Computed: true,
						},

						"iops": {
							Type:     schema.TypeInt,
							Computed: true,
						},

						"snapshot_id": {
							Type:     schema.TypeString,
							Computed: true,
						},

						"volume_size": {
							Type:     schema.TypeInt,
							Computed: true,
						},

						"volume_type": {
							Type:     schema.TypeString,
							Computed: true,
						},
					},
				},
			},
			"root_block_device": {
				Type:     schema.TypeSet,
				Computed: true,
				Elem: &schema.Resource{
					Schema: map[string]*schema.Schema{
						"delete_on_termination": {
							Type:     schema.TypeBool,
							Computed: true,
						},

						"iops": {
							Type:     schema.TypeInt,
							Computed: true,
						},

						"volume_size": {
							Type:     schema.TypeInt,
							Computed: true,
						},

						"volume_type": {
							Type:     schema.TypeString,
							Computed: true,
						},
					},
				},
			},
		},
	}
}

// dataSourceAwsInstanceRead performs the instanceID lookup
func dataSourceAwsInstanceRead(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*AWSClient).ec2conn

	filters, filtersOk := d.GetOk("filter")
	instanceID, instanceIDOk := d.GetOk("instance_id")
	tags, tagsOk := d.GetOk("instance_tags")

	if filtersOk == false && instanceIDOk == false && tagsOk == false {
		return fmt.Errorf("One of filters, instance_tags, or instance_id must be assigned")
	}

	// Build up search parameters
	params := &ec2.DescribeInstancesInput{}
	if filtersOk {
		params.Filters = buildAwsDataSourceFilters(filters.(*schema.Set))
	}
	if instanceIDOk {
		params.InstanceIds = []*string{aws.String(instanceID.(string))}
	}
	if tagsOk {
		params.Filters = append(params.Filters, buildEC2TagFilterList(
			tagsFromMap(tags.(map[string]interface{})),
		)...)
	}

	// Perform the lookup
	resp, err := conn.DescribeInstances(params)
	if err != nil {
		return err
	}

	// If no instances were returned, return
	if len(resp.Reservations) == 0 {
		return fmt.Errorf("Your query returned no results. Please change your search criteria and try again.")
	}

	var filteredInstances []*ec2.Instance

	// loop through reservations, and remove terminated instances, populate instance slice
	for _, res := range resp.Reservations {
		for _, instance := range res.Instances {
			if instance.State != nil && *instance.State.Name != "terminated" {
				filteredInstances = append(filteredInstances, instance)
			}
		}
	}

	var instance *ec2.Instance
	if len(filteredInstances) < 1 {
		return fmt.Errorf("Your query returned no results. Please change your search criteria and try again.")
	}

	// (TODO: Support a list of instances to be returned)
	// Possibly with a different data source that returns a list of individual instance data sources
	if len(filteredInstances) > 1 {
		return fmt.Errorf("Your query returned more than one result. Please try a more " +
			"specific search criteria.")
	} else {
		instance = filteredInstances[0]
	}

	log.Printf("[DEBUG] aws_instance - Single Instance ID found: %s", *instance.InstanceId)
	return instanceDescriptionAttributes(d, instance, conn)
}

// Populate instance attribute fields with the returned instance
func instanceDescriptionAttributes(d *schema.ResourceData, instance *ec2.Instance, conn *ec2.EC2) error {
	d.SetId(*instance.InstanceId)
	// Set the easy attributes
	d.Set("instance_state", instance.State.Name)
	if instance.Placement != nil {
		d.Set("availability_zone", instance.Placement.AvailabilityZone)
	}
	if instance.Placement.Tenancy != nil {
		d.Set("tenancy", instance.Placement.Tenancy)
	}
	d.Set("ami", instance.ImageId)
	d.Set("instance_type", instance.InstanceType)
	d.Set("key_name", instance.KeyName)
	d.Set("public_dns", instance.PublicDnsName)
	d.Set("public_ip", instance.PublicIpAddress)
	d.Set("private_dns", instance.PrivateDnsName)
	d.Set("private_ip", instance.PrivateIpAddress)
	d.Set("iam_instance_profile", iamInstanceProfileArnToName(instance.IamInstanceProfile))

	// iterate through network interfaces, and set subnet, network_interface, public_addr
	if len(instance.NetworkInterfaces) > 0 {
		for _, ni := range instance.NetworkInterfaces {
			if *ni.Attachment.DeviceIndex == 0 {
				d.Set("subnet_id", ni.SubnetId)
				d.Set("network_interface_id", ni.NetworkInterfaceId)
				d.Set("associate_public_ip_address", ni.Association != nil)
			}
		}
	} else {
		d.Set("subnet_id", instance.SubnetId)
		d.Set("network_interface_id", "")
	}

	d.Set("ebs_optimized", instance.EbsOptimized)
	if instance.SubnetId != nil && *instance.SubnetId != "" {
		d.Set("source_dest_check", instance.SourceDestCheck)
	}

	if instance.Monitoring != nil && instance.Monitoring.State != nil {
		monitoringState := *instance.Monitoring.State
		d.Set("monitoring", monitoringState == "enabled" || monitoringState == "pending")
	}

	d.Set("tags", dataSourceTags(instance.Tags))

	// Security Groups
	if err := readSecurityGroups(d, instance); err != nil {
		return err
	}

	// Block devices
	if err := readBlockDevices(d, instance, conn); err != nil {
		return err
	}
	if _, ok := d.GetOk("ephemeral_block_device"); !ok {
		d.Set("ephemeral_block_device", []interface{}{})
	}

	// Lookup and Set Instance Attributes
	{
		attr, err := conn.DescribeInstanceAttribute(&ec2.DescribeInstanceAttributeInput{
			Attribute:  aws.String("disableApiTermination"),
			InstanceId: aws.String(d.Id()),
		})
		if err != nil {
			return err
		}
		d.Set("disable_api_termination", attr.DisableApiTermination.Value)
	}
	{
		attr, err := conn.DescribeInstanceAttribute(&ec2.DescribeInstanceAttributeInput{
			Attribute:  aws.String(ec2.InstanceAttributeNameUserData),
			InstanceId: aws.String(d.Id()),
		})
		if err != nil {
			return err
		}
		if attr.UserData.Value != nil {
			d.Set("user_data", userDataHashSum(*attr.UserData.Value))
		}
	}

	return nil
}