package terraform

import (
	"fmt"
	"reflect"
	"regexp"
	"strconv"
	"strings"

	"github.com/hashicorp/terraform/config"
	"github.com/hashicorp/terraform/config/module"
)

// ResourceAddress is a way of identifying an individual resource (or,
// eventually, a subset of resources) within the state. It is used for Targets.
type ResourceAddress struct {
	// Addresses a resource falling somewhere in the module path
	// When specified alone, addresses all resources within a module path
	Path []string

	// Addresses a specific resource that occurs in a list
	Index int

	InstanceType    InstanceType
	InstanceTypeSet bool
	Name            string
	Type            string
	Mode            config.ResourceMode // significant only if InstanceTypeSet
}

// Copy returns a copy of this ResourceAddress
func (r *ResourceAddress) Copy() *ResourceAddress {
	if r == nil {
		return nil
	}

	n := &ResourceAddress{
		Path:         make([]string, 0, len(r.Path)),
		Index:        r.Index,
		InstanceType: r.InstanceType,
		Name:         r.Name,
		Type:         r.Type,
		Mode:         r.Mode,
	}

	n.Path = append(n.Path, r.Path...)

	return n
}

// String outputs the address that parses into this address.
func (r *ResourceAddress) String() string {
	var result []string
	for _, p := range r.Path {
		result = append(result, "module", p)
	}

	switch r.Mode {
	case config.ManagedResourceMode:
		// nothing to do
	case config.DataResourceMode:
		result = append(result, "data")
	default:
		panic(fmt.Errorf("unsupported resource mode %s", r.Mode))
	}

	if r.Type != "" {
		result = append(result, r.Type)
	}

	if r.Name != "" {
		name := r.Name
		if r.InstanceTypeSet {
			switch r.InstanceType {
			case TypePrimary:
				name += ".primary"
			case TypeDeposed:
				name += ".deposed"
			case TypeTainted:
				name += ".tainted"
			}
		}

		if r.Index >= 0 {
			name += fmt.Sprintf("[%d]", r.Index)
		}
		result = append(result, name)
	}

	return strings.Join(result, ".")
}

// HasResourceSpec returns true if the address has a resource spec, as
// defined in the documentation:
//    https://www.terraform.io/docs/internals/resource-addressing.html
// In particular, this returns false if the address contains only
// a module path, thus addressing the entire module.
func (r *ResourceAddress) HasResourceSpec() bool {
	return r.Type != "" && r.Name != ""
}

// WholeModuleAddress returns the resource address that refers to all
// resources in the same module as the receiver address.
func (r *ResourceAddress) WholeModuleAddress() *ResourceAddress {
	return &ResourceAddress{
		Path:            r.Path,
		Index:           -1,
		InstanceTypeSet: false,
	}
}

// MatchesConfig returns true if the receiver matches the given
// configuration resource within the given configuration module.
//
// Since resource configuration blocks represent all of the instances of
// a multi-instance resource, the index of the address (if any) is not
// considered.
func (r *ResourceAddress) MatchesConfig(mod *module.Tree, rc *config.Resource) bool {
	if r.HasResourceSpec() {
		if r.Mode != rc.Mode || r.Type != rc.Type || r.Name != rc.Name {
			return false
		}
	}

	addrPath := r.Path
	cfgPath := mod.Path()

	// normalize
	if len(addrPath) == 0 {
		addrPath = nil
	}
	if len(cfgPath) == 0 {
		cfgPath = nil
	}
	return reflect.DeepEqual(addrPath, cfgPath)
}

// stateId returns the ID that this resource should be entered with
// in the state. This is also used for diffs. In the future, we'd like to
// move away from this string field so I don't export this.
func (r *ResourceAddress) stateId() string {
	result := fmt.Sprintf("%s.%s", r.Type, r.Name)
	switch r.Mode {
	case config.ManagedResourceMode:
		// Done
	case config.DataResourceMode:
		result = fmt.Sprintf("data.%s", result)
	default:
		panic(fmt.Errorf("unknown resource mode: %s", r.Mode))
	}
	if r.Index >= 0 {
		result += fmt.Sprintf(".%d", r.Index)
	}

	return result
}

// parseResourceAddressConfig creates a resource address from a config.Resource
func parseResourceAddressConfig(r *config.Resource) (*ResourceAddress, error) {
	return &ResourceAddress{
		Type:         r.Type,
		Name:         r.Name,
		Index:        -1,
		InstanceType: TypePrimary,
		Mode:         r.Mode,
	}, nil
}

// parseResourceAddressInternal parses the somewhat bespoke resource
// identifier used in states and diffs, such as "instance.name.0".
func parseResourceAddressInternal(s string) (*ResourceAddress, error) {
	// Split based on ".". Every resource address should have at least two
	// elements (type and name).
	parts := strings.Split(s, ".")
	if len(parts) < 2 || len(parts) > 4 {
		return nil, fmt.Errorf("Invalid internal resource address format: %s", s)
	}

	// Data resource if we have at least 3 parts and the first one is data
	mode := config.ManagedResourceMode
	if len(parts) > 2 && parts[0] == "data" {
		mode = config.DataResourceMode
		parts = parts[1:]
	}

	// If we're not a data resource and we have more than 3, then it is an error
	if len(parts) > 3 && mode != config.DataResourceMode {
		return nil, fmt.Errorf("Invalid internal resource address format: %s", s)
	}

	// Build the parts of the resource address that are guaranteed to exist
	addr := &ResourceAddress{
		Type:         parts[0],
		Name:         parts[1],
		Index:        -1,
		InstanceType: TypePrimary,
		Mode:         mode,
	}

	// If we have more parts, then we have an index. Parse that.
	if len(parts) > 2 {
		idx, err := strconv.ParseInt(parts[2], 0, 0)
		if err != nil {
			return nil, fmt.Errorf("Error parsing resource address %q: %s", s, err)
		}

		addr.Index = int(idx)
	}

	return addr, nil
}

func ParseResourceAddress(s string) (*ResourceAddress, error) {
	matches, err := tokenizeResourceAddress(s)
	if err != nil {
		return nil, err
	}
	mode := config.ManagedResourceMode
	if matches["data_prefix"] != "" {
		mode = config.DataResourceMode
	}
	resourceIndex, err := ParseResourceIndex(matches["index"])
	if err != nil {
		return nil, err
	}
	instanceType, err := ParseInstanceType(matches["instance_type"])
	if err != nil {
		return nil, err
	}
	path := ParseResourcePath(matches["path"])

	// not allowed to say "data." without a type following
	if mode == config.DataResourceMode && matches["type"] == "" {
		return nil, fmt.Errorf(
			"invalid resource address %q: must target specific data instance",
			s,
		)
	}

	return &ResourceAddress{
		Path:            path,
		Index:           resourceIndex,
		InstanceType:    instanceType,
		InstanceTypeSet: matches["instance_type"] != "",
		Name:            matches["name"],
		Type:            matches["type"],
		Mode:            mode,
	}, nil
}

// ParseResourceAddressForInstanceDiff creates a ResourceAddress for a
// resource name as described in a module diff.
//
// For historical reasons a different addressing format is used in this
// context. The internal format should not be shown in the UI and instead
// this function should be used to translate to a ResourceAddress and
// then, where appropriate, use the String method to produce a canonical
// resource address string for display in the UI.
//
// The given path slice must be empty (or nil) for the root module, and
// otherwise consist of a sequence of module names traversing down into
// the module tree. If a non-nil path is provided, the caller must not
// modify its underlying array after passing it to this function.
func ParseResourceAddressForInstanceDiff(path []string, key string) (*ResourceAddress, error) {
	addr, err := parseResourceAddressInternal(key)
	if err != nil {
		return nil, err
	}
	addr.Path = path
	return addr, nil
}

// Contains returns true if and only if the given node is contained within
// the receiver.
//
// Containment is defined in terms of the module and resource heirarchy:
// a resource is contained within its module and any ancestor modules,
// an indexed resource instance is contained with the unindexed resource, etc.
func (addr *ResourceAddress) Contains(other *ResourceAddress) bool {
	ourPath := addr.Path
	givenPath := other.Path
	if len(givenPath) < len(ourPath) {
		return false
	}
	for i := range ourPath {
		if ourPath[i] != givenPath[i] {
			return false
		}
	}

	// If the receiver is a whole-module address then the path prefix
	// matching is all we need.
	if !addr.HasResourceSpec() {
		return true
	}

	if addr.Type != other.Type || addr.Name != other.Name || addr.Mode != other.Mode {
		return false
	}

	if addr.Index != -1 && addr.Index != other.Index {
		return false
	}

	if addr.InstanceTypeSet && (addr.InstanceTypeSet != other.InstanceTypeSet || addr.InstanceType != other.InstanceType) {
		return false
	}

	return true
}

// Equals returns true if the receiver matches the given address.
//
// The name of this method is a misnomer, since it doesn't test for exact
// equality. Instead, it tests that the _specified_ parts of each
// address match, treating any unspecified parts as wildcards.
//
// See also Contains, which takes a more heirarchical approach to comparing
// addresses.
func (addr *ResourceAddress) Equals(raw interface{}) bool {
	other, ok := raw.(*ResourceAddress)
	if !ok {
		return false
	}

	pathMatch := len(addr.Path) == 0 && len(other.Path) == 0 ||
		reflect.DeepEqual(addr.Path, other.Path)

	indexMatch := addr.Index == -1 ||
		other.Index == -1 ||
		addr.Index == other.Index

	nameMatch := addr.Name == "" ||
		other.Name == "" ||
		addr.Name == other.Name

	typeMatch := addr.Type == "" ||
		other.Type == "" ||
		addr.Type == other.Type

	// mode is significant only when type is set
	modeMatch := addr.Type == "" ||
		other.Type == "" ||
		addr.Mode == other.Mode

	return pathMatch &&
		indexMatch &&
		addr.InstanceType == other.InstanceType &&
		nameMatch &&
		typeMatch &&
		modeMatch
}

// Less returns true if and only if the receiver should be sorted before
// the given address when presenting a list of resource addresses to
// an end-user.
//
// This sort uses lexicographic sorting for most components, but uses
// numeric sort for indices, thus causing index 10 to sort after
// index 9, rather than after index 1.
func (addr *ResourceAddress) Less(other *ResourceAddress) bool {

	switch {

	case len(addr.Path) != len(other.Path):
		return len(addr.Path) < len(other.Path)

	case !reflect.DeepEqual(addr.Path, other.Path):
		// If the two paths are the same length but don't match, we'll just
		// cheat and compare the string forms since it's easier than
		// comparing all of the path segments in turn, and lexicographic
		// comparison is correct for the module path portion.
		addrStr := addr.String()
		otherStr := other.String()
		return addrStr < otherStr

	case addr.Mode != other.Mode:
		return addr.Mode == config.DataResourceMode

	case addr.Type != other.Type:
		return addr.Type < other.Type

	case addr.Name != other.Name:
		return addr.Name < other.Name

	case addr.Index != other.Index:
		// Since "Index" is -1 for an un-indexed address, this also conveniently
		// sorts unindexed addresses before indexed ones, should they both
		// appear for some reason.
		return addr.Index < other.Index

	case addr.InstanceTypeSet != other.InstanceTypeSet:
		return !addr.InstanceTypeSet

	case addr.InstanceType != other.InstanceType:
		// InstanceType is actually an enum, so this is just an arbitrary
		// sort based on the enum numeric values, and thus not particularly
		// meaningful.
		return addr.InstanceType < other.InstanceType

	default:
		return false

	}
}

func ParseResourceIndex(s string) (int, error) {
	if s == "" {
		return -1, nil
	}
	return strconv.Atoi(s)
}

func ParseResourcePath(s string) []string {
	if s == "" {
		return nil
	}
	parts := strings.Split(s, ".")
	path := make([]string, 0, len(parts))
	for _, s := range parts {
		// Due to the limitations of the regexp match below, the path match has
		// some noise in it we have to filter out :|
		if s == "" || s == "module" {
			continue
		}
		path = append(path, s)
	}
	return path
}

func ParseInstanceType(s string) (InstanceType, error) {
	switch s {
	case "", "primary":
		return TypePrimary, nil
	case "deposed":
		return TypeDeposed, nil
	case "tainted":
		return TypeTainted, nil
	default:
		return TypeInvalid, fmt.Errorf("Unexpected value for InstanceType field: %q", s)
	}
}

func tokenizeResourceAddress(s string) (map[string]string, error) {
	// Example of portions of the regexp below using the
	// string "aws_instance.web.tainted[1]"
	re := regexp.MustCompile(`\A` +
		// "module.foo.module.bar" (optional)
		`(?P<path>(?:module\.(?P<module_name>[^.]+)\.?)*)` +
		// possibly "data.", if targeting is a data resource
		`(?P<data_prefix>(?:data\.)?)` +
		// "aws_instance.web" (optional when module path specified)
		`(?:(?P<type>[^.]+)\.(?P<name>[^.[]+))?` +
		// "tainted" (optional, omission implies: "primary")
		`(?:\.(?P<instance_type>\w+))?` +
		// "1" (optional, omission implies: "0")
		`(?:\[(?P<index>\d+)\])?` +
		`\z`)

	groupNames := re.SubexpNames()
	rawMatches := re.FindAllStringSubmatch(s, -1)
	if len(rawMatches) != 1 {
		return nil, fmt.Errorf("invalid resource address %q", s)
	}

	matches := make(map[string]string)
	for i, m := range rawMatches[0] {
		matches[groupNames[i]] = m
	}

	return matches, nil
}