package fastly

import (
	"errors"
	"fmt"
	"log"
	"time"

	"github.com/hashicorp/terraform/helper/schema"
	gofastly "github.com/sethvargo/go-fastly"
)

var fastlyNoServiceFoundErr = errors.New("No matching Fastly Service found")

func resourceServiceV1() *schema.Resource {
	return &schema.Resource{
		Create: resourceServiceV1Create,
		Read:   resourceServiceV1Read,
		Update: resourceServiceV1Update,
		Delete: resourceServiceV1Delete,

		Schema: map[string]*schema.Schema{
			"name": &schema.Schema{
				Type:        schema.TypeString,
				Required:    true,
				Description: "Unique name for this Service",
			},

			// Active Version represents the currently activated version in Fastly. In
			// Terraform, we abstract this number away from the users and manage
			// creating and activating. It's used internally, but also exported for
			// users to see.
			"active_version": &schema.Schema{
				Type:     schema.TypeString,
				Computed: true,
			},

			"domain": &schema.Schema{
				Type:     schema.TypeSet,
				Required: true,
				Elem: &schema.Resource{
					Schema: map[string]*schema.Schema{
						"name": &schema.Schema{
							Type:        schema.TypeString,
							Required:    true,
							Description: "The domain that this Service will respond to",
						},

						"comment": &schema.Schema{
							Type:     schema.TypeString,
							Optional: true,
						},
					},
				},
			},

			"default_ttl": &schema.Schema{
				Type:        schema.TypeInt,
				Optional:    true,
				Default:     3600,
				Description: "The default Time-to-live (TTL) for the version",
			},

			"default_host": &schema.Schema{
				Type:        schema.TypeString,
				Optional:    true,
				Computed:    true,
				Description: "The default hostname for the version",
			},

			"backend": &schema.Schema{
				Type:     schema.TypeSet,
				Required: true,
				Elem: &schema.Resource{
					Schema: map[string]*schema.Schema{
						// required fields
						"name": &schema.Schema{
							Type:        schema.TypeString,
							Required:    true,
							Description: "A name for this Backend",
						},
						"address": &schema.Schema{
							Type:        schema.TypeString,
							Required:    true,
							Description: "An IPv4, hostname, or IPv6 address for the Backend",
						},
						// Optional fields, defaults where they exist
						"auto_loadbalance": &schema.Schema{
							Type:        schema.TypeBool,
							Optional:    true,
							Default:     true,
							Description: "Should this Backend be load balanced",
						},
						"between_bytes_timeout": &schema.Schema{
							Type:        schema.TypeInt,
							Optional:    true,
							Default:     10000,
							Description: "How long to wait between bytes in milliseconds",
						},
						"connect_timeout": &schema.Schema{
							Type:        schema.TypeInt,
							Optional:    true,
							Default:     1000,
							Description: "How long to wait for a timeout in milliseconds",
						},
						"error_threshold": &schema.Schema{
							Type:        schema.TypeInt,
							Optional:    true,
							Default:     0,
							Description: "Number of errors to allow before the Backend is marked as down",
						},
						"first_byte_timeout": &schema.Schema{
							Type:        schema.TypeInt,
							Optional:    true,
							Default:     15000,
							Description: "How long to wait for the first bytes in milliseconds",
						},
						"max_conn": &schema.Schema{
							Type:        schema.TypeInt,
							Optional:    true,
							Default:     200,
							Description: "Maximum number of connections for this Backend",
						},
						"port": &schema.Schema{
							Type:        schema.TypeInt,
							Optional:    true,
							Default:     80,
							Description: "The port number Backend responds on. Default 80",
						},
						"ssl_check_cert": &schema.Schema{
							Type:        schema.TypeBool,
							Optional:    true,
							Default:     true,
							Description: "Be strict on checking SSL certs",
						},
						// UseSSL is something we want to support in the future, but
						// requires SSL setup we don't yet have
						// TODO: Provide all SSL fields from https://docs.fastly.com/api/config#backend
						// "use_ssl": &schema.Schema{
						// 	Type:        schema.TypeBool,
						// 	Optional:    true,
						// 	Default:     false,
						// 	Description: "Whether or not to use SSL to reach the Backend",
						// },
						"weight": &schema.Schema{
							Type:        schema.TypeInt,
							Optional:    true,
							Default:     100,
							Description: "How long to wait for the first bytes in milliseconds",
						},
					},
				},
			},

			"force_destroy": &schema.Schema{
				Type:     schema.TypeBool,
				Optional: true,
			},
		},
	}
}

func resourceServiceV1Create(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*FastlyClient).conn
	service, err := conn.CreateService(&gofastly.CreateServiceInput{
		Name:    d.Get("name").(string),
		Comment: "Managed by Terraform",
	})

	if err != nil {
		return err
	}

	d.SetId(service.ID)
	return resourceServiceV1Update(d, meta)
}

func resourceServiceV1Update(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*FastlyClient).conn

	// Update Name. No new verions is required for this
	if d.HasChange("name") {
		_, err := conn.UpdateService(&gofastly.UpdateServiceInput{
			ID:   d.Id(),
			Name: d.Get("name").(string),
		})
		if err != nil {
			return err
		}
	}

	// Once activated, Versions are locked and become immutable. This is true for
	// versions that are no longer active. For Domains, Backends, DefaultHost and
	// DefaultTTL, a new Version must be created first, and updates posted to that
	// Version. Loop these attributes and determine if we need to create a new version first
	var needsChange bool
	for _, v := range []string{"domain", "backend", "default_host", "default_ttl"} {
		if d.HasChange(v) {
			needsChange = true
		}
	}

	if needsChange {
		latestVersion := d.Get("active_version").(string)
		if latestVersion == "" {
			// If the service was just created, there is an empty Version 1 available
			// that is unlocked and can be updated
			latestVersion = "1"
		} else {
			// Clone the latest version, giving us an unlocked version we can modify
			log.Printf("[DEBUG] Creating clone of version (%s) for updates", latestVersion)
			newVersion, err := conn.CloneVersion(&gofastly.CloneVersionInput{
				Service: d.Id(),
				Version: latestVersion,
			})
			if err != nil {
				return err
			}

			// The new version number is named "Number", but it's actually a string
			latestVersion = newVersion.Number

			// New versions are not immediately found in the API, or are not
			// immediately mutable, so we need to sleep a few and let Fastly ready
			// itself. Typically, 7 seconds is enough
			log.Printf("[DEBUG] Sleeping 7 seconds to allow Fastly Version to be available")
			time.Sleep(7 * time.Second)
		}

		// update general settings
		if d.HasChange("default_host") || d.HasChange("default_ttl") {
			opts := gofastly.UpdateSettingsInput{
				Service: d.Id(),
				Version: latestVersion,
				// default_ttl has the same default value of 3600 that is provided by
				// the Fastly API, so it's safe to include here
				DefaultTTL: uint(d.Get("default_ttl").(int)),
			}

			if attr, ok := d.GetOk("default_host"); ok {
				opts.DefaultHost = attr.(string)
			}

			log.Printf("[DEBUG] Update Settings opts: %#v", opts)
			_, err := conn.UpdateSettings(&opts)
			if err != nil {
				return err
			}
		}

		// Find differences in domains
		if d.HasChange("domain") {
			// Note: we don't utilize the PUT endpoint to update a Domain, we simply
			// destroy it and create a new one. This is how Terraform works with nested
			// sub resources, we only get the full diff not a partial set item diff.
			// Because this is done on a new version of the configuration, this is
			// considered safe
			od, nd := d.GetChange("domain")
			if od == nil {
				od = new(schema.Set)
			}
			if nd == nil {
				nd = new(schema.Set)
			}

			ods := od.(*schema.Set)
			nds := nd.(*schema.Set)

			remove := ods.Difference(nds).List()
			add := nds.Difference(ods).List()

			// Delete removed domains
			for _, dRaw := range remove {
				df := dRaw.(map[string]interface{})
				opts := gofastly.DeleteDomainInput{
					Service: d.Id(),
					Version: latestVersion,
					Name:    df["name"].(string),
				}

				log.Printf("[DEBUG] Fastly Domain Removal opts: %#v", opts)
				err := conn.DeleteDomain(&opts)
				if err != nil {
					return err
				}
			}

			// POST new Domains
			for _, dRaw := range add {
				df := dRaw.(map[string]interface{})
				opts := gofastly.CreateDomainInput{
					Service: d.Id(),
					Version: latestVersion,
					Name:    df["name"].(string),
				}

				if v, ok := df["comment"]; ok {
					opts.Comment = v.(string)
				}

				log.Printf("[DEBUG] Fastly Domain Addition opts: %#v", opts)
				_, err := conn.CreateDomain(&opts)
				if err != nil {
					return err
				}
			}
		}

		// find difference in backends
		if d.HasChange("backend") {
			// POST new Backends
			// Note: we don't utilize the PUT endpoint to update a Backend, we simply
			// destroy it and create a new one. This is how Terraform works with nested
			// sub resources, we only get the full diff not a partial set item diff.
			// Because this is done on a new version of the configuration, this is
			// considered safe
			ob, nb := d.GetChange("backend")
			if ob == nil {
				ob = new(schema.Set)
			}
			if nb == nil {
				nb = new(schema.Set)
			}

			obs := ob.(*schema.Set)
			nbs := nb.(*schema.Set)
			removeBackends := obs.Difference(nbs).List()
			addBackends := nbs.Difference(obs).List()

			// DELETE old Backends
			for _, bRaw := range removeBackends {
				bf := bRaw.(map[string]interface{})
				opts := gofastly.DeleteBackendInput{
					Service: d.Id(),
					Version: latestVersion,
					Name:    bf["name"].(string),
				}

				log.Printf("[DEBUG] Fastly Backend Removal opts: %#v", opts)
				err := conn.DeleteBackend(&opts)
				if err != nil {
					return err
				}
			}

			for _, dRaw := range addBackends {
				df := dRaw.(map[string]interface{})
				opts := gofastly.CreateBackendInput{
					Service:             d.Id(),
					Version:             latestVersion,
					Name:                df["name"].(string),
					Address:             df["address"].(string),
					AutoLoadbalance:     df["auto_loadbalance"].(bool),
					SSLCheckCert:        df["ssl_check_cert"].(bool),
					Port:                uint(df["port"].(int)),
					BetweenBytesTimeout: uint(df["between_bytes_timeout"].(int)),
					ConnectTimeout:      uint(df["connect_timeout"].(int)),
					ErrorThreshold:      uint(df["error_threshold"].(int)),
					FirstByteTimeout:    uint(df["first_byte_timeout"].(int)),
					MaxConn:             uint(df["max_conn"].(int)),
					Weight:              uint(df["weight"].(int)),
				}

				log.Printf("[DEBUG] Create Backend Opts: %#v", opts)
				_, err := conn.CreateBackend(&opts)
				if err != nil {
					return err
				}
			}
		}

		// validate version
		log.Printf("[DEBUG] Validating Fastly Service (%s), Version (%s)", d.Id(), latestVersion)
		valid, msg, err := conn.ValidateVersion(&gofastly.ValidateVersionInput{
			Service: d.Id(),
			Version: latestVersion,
		})

		if err != nil {
			return fmt.Errorf("[ERR] Error checking validation: %s", err)
		}

		if !valid {
			return fmt.Errorf("[ERR] Invalid configuration for Fastly Service (%s): %s", d.Id(), msg)
		}

		log.Printf("[DEBUG] Activating Fastly Service (%s), Version (%s)", d.Id(), latestVersion)
		_, err = conn.ActivateVersion(&gofastly.ActivateVersionInput{
			Service: d.Id(),
			Version: latestVersion,
		})
		if err != nil {
			return fmt.Errorf("[ERR] Error activating version (%s): %s", latestVersion, err)
		}

		// Only if the version is valid and activated do we set the active_version.
		// This prevents us from getting stuck in cloning an invalid version
		d.Set("active_version", latestVersion)
	}

	return resourceServiceV1Read(d, meta)
}

func resourceServiceV1Read(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*FastlyClient).conn

	// Find the Service. Discard the service because we need the ServiceDetails,
	// not just a Service record
	_, err := findService(d.Id(), meta)
	if err != nil {
		switch err {
		case fastlyNoServiceFoundErr:
			log.Printf("[WARN] %s for ID (%s)", err, d.Id())
			d.SetId("")
			return nil
		default:
			return err
		}
	}

	s, err := conn.GetServiceDetails(&gofastly.GetServiceInput{
		ID: d.Id(),
	})

	if err != nil {
		return err
	}

	d.Set("name", s.Name)
	d.Set("active_version", s.ActiveVersion.Number)

	// If CreateService succeeds, but initial updates to the Service fail, we'll
	// have an empty ActiveService version (no version is active, so we can't
	// query for information on it)
	if s.ActiveVersion.Number != "" {
		settingsOpts := gofastly.GetSettingsInput{
			Service: d.Id(),
			Version: s.ActiveVersion.Number,
		}
		if settings, err := conn.GetSettings(&settingsOpts); err == nil {
			d.Set("default_host", settings.DefaultHost)
			d.Set("default_ttl", settings.DefaultTTL)
		} else {
			return fmt.Errorf("[ERR] Error looking up Version settings for (%s), version (%s): %s", d.Id(), s.ActiveVersion.Number, err)
		}

		// TODO: update go-fastly to support an ActiveVersion struct, which contains
		// domain and backend info in the response. Here we do 2 additional queries
		// to find out that info
		domainList, err := conn.ListDomains(&gofastly.ListDomainsInput{
			Service: d.Id(),
			Version: s.ActiveVersion.Number,
		})

		if err != nil {
			return fmt.Errorf("[ERR] Error looking up Domains for (%s), version (%s): %s", d.Id(), s.ActiveVersion.Number, err)
		}

		// Refresh Domains
		dl := flattenDomains(domainList)

		if err := d.Set("domain", dl); err != nil {
			log.Printf("[WARN] Error setting Domains for (%s): %s", d.Id(), err)
		}

		// Refresh Backends
		backendList, err := conn.ListBackends(&gofastly.ListBackendsInput{
			Service: d.Id(),
			Version: s.ActiveVersion.Number,
		})

		if err != nil {
			return fmt.Errorf("[ERR] Error looking up Backends for (%s), version (%s): %s", d.Id(), s.ActiveVersion.Number, err)
		}

		bl := flattenBackends(backendList)

		if err := d.Set("backend", bl); err != nil {
			log.Printf("[WARN] Error setting Backends for (%s): %s", d.Id(), err)
		}
	} else {
		log.Printf("[DEBUG] Active Version for Service (%s) is empty, no state to refresh", d.Id())
	}

	return nil
}

func resourceServiceV1Delete(d *schema.ResourceData, meta interface{}) error {
	conn := meta.(*FastlyClient).conn

	// Fastly will fail to delete any service with an Active Version.
	// If `force_destroy` is given, we deactivate the active version and then send
	// the DELETE call
	if d.Get("force_destroy").(bool) {
		s, err := conn.GetServiceDetails(&gofastly.GetServiceInput{
			ID: d.Id(),
		})

		if err != nil {
			return err
		}

		if s.ActiveVersion.Number != "" {
			_, err := conn.DeactivateVersion(&gofastly.DeactivateVersionInput{
				Service: d.Id(),
				Version: s.ActiveVersion.Number,
			})
			if err != nil {
				return err
			}
		}
	}

	err := conn.DeleteService(&gofastly.DeleteServiceInput{
		ID: d.Id(),
	})

	if err != nil {
		return err
	}

	_, err = findService(d.Id(), meta)
	if err != nil {
		switch err {
		// we expect no records to be found here
		case fastlyNoServiceFoundErr:
			d.SetId("")
			return nil
		default:
			return err
		}
	}

	// findService above returned something and nil error, but shouldn't have
	return fmt.Errorf("[WARN] Tried deleting Service (%s), but was still found", d.Id())

}

func flattenDomains(list []*gofastly.Domain) []map[string]interface{} {
	dl := make([]map[string]interface{}, 0, len(list))

	for _, d := range list {
		dl = append(dl, map[string]interface{}{
			"name":    d.Name,
			"comment": d.Comment,
		})
	}

	return dl
}

func flattenBackends(backendList []*gofastly.Backend) []map[string]interface{} {
	var bl []map[string]interface{}
	for _, b := range backendList {
		// Convert Backend to a map for saving to state.
		nb := map[string]interface{}{
			"name":                  b.Name,
			"address":               b.Address,
			"auto_loadbalance":      b.AutoLoadbalance,
			"between_bytes_timeout": int(b.BetweenBytesTimeout),
			"connect_timeout":       int(b.ConnectTimeout),
			"error_threshold":       int(b.ErrorThreshold),
			"first_byte_timeout":    int(b.FirstByteTimeout),
			"max_conn":              int(b.MaxConn),
			"port":                  int(b.Port),
			"ssl_check_cert":        b.SSLCheckCert,
			"weight":                int(b.Weight),
		}

		bl = append(bl, nb)
	}
	return bl
}

// findService finds a Fastly Service via the ListServices endpoint, returning
// the Service if found.
//
// Fastly API does not include any "deleted_at" type parameter to indicate
// that a Service has been deleted. GET requests to a deleted Service will
// return 200 OK and have the full output of the Service for an unknown time
// (days, in my testing). In order to determine if a Service is deleted, we
// need to hit /service and loop the returned Services, searching for the one
// in question. This endpoint only returns active or "alive" services. If the
// Service is not included, then it's "gone"
//
// Returns a fastlyNoServiceFoundErr error if the Service is not found in the
// ListServices response.
func findService(id string, meta interface{}) (*gofastly.Service, error) {
	conn := meta.(*FastlyClient).conn

	l, err := conn.ListServices(&gofastly.ListServicesInput{})
	if err != nil {
		return nil, fmt.Errorf("[WARN] Error listing servcies when deleting Fastly Service (%s): %s", id, err)
	}

	for _, s := range l {
		if s.ID == id {
			log.Printf("[DEBUG] Found Service (%s)", id)
			return s, nil
		}
	}

	return nil, fastlyNoServiceFoundErr
}