package main

import (
	"fmt"
	"os"
	"regexp"
	"strconv"
	"strings"
)

// keyNames contains the names of the keys to check for in each resource in the
// state file. This allows us to support multiple types of resource without too
// much fuss.
var keyNames []string
var nameParser *regexp.Regexp

func init() {
	keyNames = []string{
		"ipv4_address",                     // DO and SoftLayer and HetznerCloud
		"public_ip",                        // AWS
		"public_ipv6",                      // Scaleway
		"ipaddress",                        // CS
		"ip_address",                       // VMware, Docker, Linode
		"private_ip",                       // AWS
		"network_interface.0.ipv4_address", // VMware
		"default_ip_address",               // provider.vsphere v1.1.1
		"access_ip_v4",                     // OpenStack
		"floating_ip",                      // OpenStack
		"network_interface.0.access_config.0.nat_ip",          // GCE
		"network_interface.0.access_config.0.assigned_nat_ip", // GCE
		"network_interface.0.address",                         // GCE
		"ipv4_address_private",                                // SoftLayer
		"networks.0.ip4address",                               // Exoscale
		"primaryip",                                           // Joyent Triton
		"network_interface.0.addresses.0",                     // Libvirt
		"network.0.address",                                   // Packet
		"primary_ip",                                          // Profitbricks
		"nic_list.0.ip_endpoint_list.0.ip",                    // Nutanix
		"network_interface.0.nat_ip_address",                  // Yandex
		"network_interface.0.ip_address",                      // Yandex
		"default_ipv4_address",                                // Telmate/Proxmox
		"ssh_host",                                            // Telmate/Proxmox
	}

	// Formats:
	// - type.[module_]name (no `count` attribute; contains module name if we're not in the root module)
	// - type.[module_]name.0 (if resource has `count` attribute)
	// - type.[module_]name.resource_name
	// - "data." prefix should not parse and be ignored by caller (does not represent a host)
	nameParser = regexp.MustCompile(`^([\w\-]+)\.([\w\-]+)(?:\.(\d+|[\S+]+))?$`)
}

type Resource struct {

	// The state (as unmarshalled from the statefile) which this resource wraps.
	// Everything which Terraform knows about the resource can be found in here.
	State resourceState

	// The key name of the resource, provided to the constructor. Unfortunately,
	// it seems like the counter index can only be found here.
	keyName string

	// Extracted from keyName
	resourceType string
	baseName     string

	// counterNumeric is 0 for resources created without `count=` attribute or
	// having a non-numeric string index
	counterNumeric int
	// counterStr is set if the resource index (e.g. in `for_each`-constructed
	// resources) is not a number.
	counterStr string
}

func NewResource(keyName string, state resourceState) (*Resource, error) {
	m := nameParser.FindStringSubmatch(keyName)

	// This should not happen unless our regex changes.
	if len(m) != 4 {
		return nil, fmt.Errorf("couldn't parse resource keyName: %s", keyName)
	}

	counterNumeric := 0
	counterStr := ""
	var err error
	if m[3] != "" {
		// The third section should be the index, if it's present. Not sure what
		// else we can do other than panic (which seems highly undesirable) if that
		// isn't the case. With Terraform 0.12 for_each syntax, index can also be
		// a non-numeric string (loop over any string value).
		counterNumeric, err = strconv.Atoi(m[3])
		if err != nil {
			counterNumeric = 0
			counterStr = m[3]
		}
	}

	return &Resource{
		State:          state,
		keyName:        keyName,
		resourceType:   m[1],
		baseName:       m[2],
		counterNumeric: counterNumeric,
		counterStr:     counterStr,
	}, nil
}

func (r Resource) IsSupported() bool {
	return r.Address() != ""
}

// Tags returns a map of arbitrary key/value pairs explicitly associated with
// the resource. Different providers have different mechanisms for attaching
// these.
func (r Resource) Tags() map[string]string {
	t := map[string]string{}

	switch r.resourceType {
	case "openstack_compute_instance_v2":
		for k, v := range r.Attributes() {
			parts := strings.SplitN(k, ".", 2)
			// At some point Terraform changed the key for counts of attributes to end with ".%"
			// instead of ".#". Both need to be considered as Terraform still supports state
			// files using the old format.
			if len(parts) == 2 && parts[0] == "metadata" && parts[1] != "#" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			}
		}
	case "opentelekomcloud_compute_instance_v2":
		for k, v := range r.Attributes() {
			parts := strings.SplitN(k, ".", 2)
			// At some point Terraform changed the key for counts of attributes to end with ".%"
			// instead of ".#". Both need to be considered as Terraform still supports state
			// files using the old format.
			if len(parts) == 2 && parts[0] == "tag" && parts[1] != "#" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			} else if len(parts) == 2 && parts[0] == "metadata" && parts[1] != "#" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			}
		}
	case "aws_instance", "linode_instance":
		for k, v := range r.Attributes() {
			parts := strings.SplitN(k, ".", 2)
			// At some point Terraform changed the key for counts of attributes to end with ".%"
			// instead of ".#". Both need to be considered as Terraform still supports state
			// files using the old format.
			if len(parts) == 2 && (parts[0] == "tags" || parts[0] == "tags_all") && parts[1] != "#" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			}
		}
	case "aws_spot_instance_request":
		for k, v := range r.Attributes() {
			parts := strings.SplitN(k, ".", 2)
			// At some point Terraform changed the key for counts of attributes to end with ".%"
			// instead of ".#". Both need to be considered as Terraform still supports state
			// files using the old format.
			if len(parts) == 2 && (parts[0] == "tags" || parts[0] == "tags_all") && parts[1] != "#" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			}
		}
	case "vsphere_virtual_machine":
		for k, v := range r.Attributes() {
			parts := strings.SplitN(k, ".", 2)

			if len(parts) == 2 && parts[0] == "custom_configuration_parameters" && parts[1] != "#" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			}
			if len(parts) == 2 && parts[0] == "tags" && parts[1] != "#" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			}
		}
	case "digitalocean_droplet", "google_compute_instance", "scaleway_server":
		for k, v := range r.Attributes() {
			parts := strings.SplitN(k, ".", 2)
			if len(parts) == 2 && parts[0] == "tags" && parts[1] != "#" {
				vv := strings.ToLower(v)
				t[vv] = ""
			}
		}
	case "triton_machine", "exoscale_compute":
		for k, v := range r.Attributes() {
			parts := strings.SplitN(k, ".", 2)
			if len(parts) == 2 && parts[0] == "tags" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			}
		}
	case "yandex_compute_instance", "hcloud_server":
		for k, v := range r.Attributes() {
			parts := strings.SplitN(k, ".", 2)
			// At some point Terraform changed the key for counts of attributes to end with ".%"
			// instead of ".#". Both need to be considered as Terraform still supports state
			// files using the old format.
			if len(parts) == 2 && parts[0] == "labels" && parts[1] != "#" && parts[1] != "%" {
				kk := strings.ToLower(parts[1])
				vv := strings.ToLower(v)
				t[kk] = vv
			}
		}
	}

	return t
}

// Attributes returns a map containing everything we know about this resource.
func (r Resource) Attributes() map[string]string {
	return r.State.Primary.Attributes
}

// Hostname returns the hostname of this resource.
func (r Resource) Hostname() string {
	if keyName := os.Getenv("TF_HOSTNAME_KEY_NAME"); keyName != "" {
		if ip := r.State.Primary.Attributes[keyName]; ip != "" {
			return ip
		}
	}

	return r.Address()
}

// Address returns the IP address of this resource.
func (r Resource) Address() string {
	if keyName := os.Getenv("TF_KEY_NAME"); keyName != "" {
		if ip := r.State.Primary.Attributes[keyName]; ip != "" {
			return ip
		}
	} else {
		for _, key := range keyNames {
			if ip := r.State.Primary.Attributes[key]; ip != "" {
				return ip
			}
		}
	}

	return ""
}