package aws

import (
	"fmt"
	"log"
	"sort"
	"time"

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

func dataSourceAwsAvailabilityZones() *schema.Resource {
	return &schema.Resource{
		Read: dataSourceAwsAvailabilityZonesRead,

		Schema: map[string]*schema.Schema{
			"names": &schema.Schema{
				Type:     schema.TypeList,
				Computed: true,
				Elem:     &schema.Schema{Type: schema.TypeString},
			},
			"state": &schema.Schema{
				Type:         schema.TypeString,
				Optional:     true,
				ValidateFunc: validateStateType,
			},
		},
	}
}

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

	log.Printf("[DEBUG] Reading Availability Zones.")
	d.SetId(time.Now().UTC().String())

	request := &ec2.DescribeAvailabilityZonesInput{}

	if v, ok := d.GetOk("state"); ok {
		request.Filters = []*ec2.Filter{
			&ec2.Filter{
				Name:   aws.String("state"),
				Values: []*string{aws.String(v.(string))},
			},
		}
	}

	log.Printf("[DEBUG] Availability Zones request options: %#v", *request)

	resp, err := conn.DescribeAvailabilityZones(request)
	if err != nil {
		return fmt.Errorf("Error fetching Availability Zones: %s", err)
	}

	raw := make([]string, len(resp.AvailabilityZones))
	for i, v := range resp.AvailabilityZones {
		raw[i] = *v.ZoneName
	}

	sort.Strings(raw)

	if err := d.Set("names", raw); err != nil {
		return fmt.Errorf("[WARN] Error setting Availability Zones: %s", err)
	}

	return nil
}

func validateStateType(v interface{}, k string) (ws []string, errors []error) {
	value := v.(string)

	validState := map[string]bool{
		"available":   true,
		"information": true,
		"impaired":    true,
		"unavailable": true,
	}

	if !validState[value] {
		errors = append(errors, fmt.Errorf(
			"%q contains an invalid Availability Zone state %q. Valid states are: %q, %q, %q and %q.",
			k, value, "available", "information", "impaired", "unavailable"))
	}
	return
}