package aws

import (
	"errors"
	"fmt"
	"log"
	"math/rand"
	"time"

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

func resourceAwsIamUserLoginProfile() *schema.Resource {
	return &schema.Resource{
		Create: resourceAwsIamUserLoginProfileCreate,
		Read:   schema.Noop,
		Update: schema.Noop,
		Delete: schema.RemoveFromState,

		Schema: map[string]*schema.Schema{
			"user": {
				Type:     schema.TypeString,
				Required: true,
			},
			"pgp_key": {
				Type:     schema.TypeString,
				Required: true,
			},
			"password_reset_required": {
				Type:     schema.TypeBool,
				Optional: true,
				Default:  true,
			},
			"password_length": {
				Type:         schema.TypeInt,
				Optional:     true,
				Default:      20,
				ValidateFunc: validateAwsIamLoginProfilePasswordLength,
			},

			"key_fingerprint": {
				Type:     schema.TypeString,
				Computed: true,
			},
			"encrypted_password": {
				Type:     schema.TypeString,
				Computed: true,
			},
		},
	}
}

func validateAwsIamLoginProfilePasswordLength(v interface{}, _ string) (_ []string, es []error) {
	length := v.(int)
	if length < 4 {
		es = append(es, errors.New("minimum password_length is 4 characters"))
	}
	if length > 128 {
		es = append(es, errors.New("maximum password_length is 128 characters"))
	}
	return
}

// generatePassword generates a random password of a given length using
// characters that are likely to satisfy any possible AWS password policy
// (given sufficient length).
func generatePassword(length int) string {
	charsets := []string{
		"abcdefghijklmnopqrstuvwxyz",
		"ABCDEFGHIJKLMNOPQRSTUVWXYZ",
		"012346789",
		"!@#$%^&*()_+-=[]{}|'",
	}

	// Use all character sets
	random := rand.New(rand.NewSource(time.Now().UTC().UnixNano()))
	components := make(map[int]byte, length)
	for i := 0; i < length; i++ {
		charset := charsets[i%len(charsets)]
		components[i] = charset[random.Intn(len(charset))]
	}

	// Randomise the ordering so we don't end up with a predictable
	// lower case, upper case, numeric, symbol pattern
	result := make([]byte, length)
	i := 0
	for _, b := range components {
		result[i] = b
		i = i + 1
	}

	return string(result)
}

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

	encryptionKey, err := encryption.RetrieveGPGKey(d.Get("pgp_key").(string))
	if err != nil {
		return err
	}

	username := d.Get("user").(string)
	passwordResetRequired := d.Get("password_reset_required").(bool)
	passwordLength := d.Get("password_length").(int)

	_, err = iamconn.GetLoginProfile(&iam.GetLoginProfileInput{
		UserName: aws.String(username),
	})
	if err != nil {
		if awsErr, ok := err.(awserr.Error); ok && awsErr.Code() != "NoSuchEntity" {
			// If there is already a login profile, bring it under management (to prevent
			// resource creation diffs) - we will never modify it, but obviously cannot
			// set the password.
			d.SetId(username)
			d.Set("key_fingerprint", "")
			d.Set("encrypted_password", "")
			return nil
		}
	}

	initialPassword := generatePassword(passwordLength)
	fingerprint, encrypted, err := encryption.EncryptValue(encryptionKey, initialPassword, "Password")
	if err != nil {
		return err
	}

	request := &iam.CreateLoginProfileInput{
		UserName:              aws.String(username),
		Password:              aws.String(initialPassword),
		PasswordResetRequired: aws.Bool(passwordResetRequired),
	}

	log.Println("[DEBUG] Create IAM User Login Profile request:", request)
	createResp, err := iamconn.CreateLoginProfile(request)
	if err != nil {
		if awsErr, ok := err.(awserr.Error); ok && awsErr.Code() == "EntityAlreadyExists" {
			// If there is already a login profile, bring it under management (to prevent
			// resource creation diffs) - we will never modify it, but obviously cannot
			// set the password.
			d.SetId(username)
			d.Set("key_fingerprint", "")
			d.Set("encrypted_password", "")
			return nil
		}
		return errwrap.Wrapf(fmt.Sprintf("Error creating IAM User Login Profile for %q: {{err}}", username), err)
	}

	d.SetId(*createResp.LoginProfile.UserName)
	d.Set("key_fingerprint", fingerprint)
	d.Set("encrypted_password", encrypted)
	return nil
}