package api

import (
	"fmt"
	"regexp"
	"strings"
	"unicode"
)

func (a *API) enableGeneratedTypedErrors() {
	switch a.Metadata.Protocol {
	case "json":
	case "rest-json":
	default:
		return
	}

	a.WithGeneratedTypedErrors = true
}

// updateTopLevelShapeReferences moves resultWrapper, locationName, and
// xmlNamespace traits from toplevel shape references to the toplevel
// shapes for easier code generation
func (a *API) updateTopLevelShapeReferences() {
	for _, o := range a.Operations {
		// these are for REST-XML services
		if o.InputRef.LocationName != "" {
			o.InputRef.Shape.LocationName = o.InputRef.LocationName
		}
		if o.InputRef.Location != "" {
			o.InputRef.Shape.Location = o.InputRef.Location
		}
		if o.InputRef.Payload != "" {
			o.InputRef.Shape.Payload = o.InputRef.Payload
		}
		if o.InputRef.XMLNamespace.Prefix != "" {
			o.InputRef.Shape.XMLNamespace.Prefix = o.InputRef.XMLNamespace.Prefix
		}
		if o.InputRef.XMLNamespace.URI != "" {
			o.InputRef.Shape.XMLNamespace.URI = o.InputRef.XMLNamespace.URI
		}
	}

}

// writeShapeNames sets each shape's API and shape name values. Binding the
// shape to its parent API. This will set OrigShapeName on each Shape and ShapeRef
// to allow access to the original shape name for code generation.
func (a *API) writeShapeNames() {
	writeOrigShapeName := func(s *ShapeRef) {
		if len(s.ShapeName) > 0 {
			s.OrigShapeName = s.ShapeName
		}
	}

	for n, s := range a.Shapes {
		s.API = a
		s.ShapeName, s.OrigShapeName = n, n
		for _, ref := range s.MemberRefs {
			writeOrigShapeName(ref)
		}
		writeOrigShapeName(&s.MemberRef)
		writeOrigShapeName(&s.KeyRef)
		writeOrigShapeName(&s.ValueRef)
	}
}

func (a *API) resolveReferences() {
	resolver := referenceResolver{API: a, visited: map[*ShapeRef]bool{}}

	for _, s := range a.Shapes {
		resolver.resolveShape(s)
	}

	for _, o := range a.Operations {
		o.API = a // resolve parent reference

		resolver.resolveReference(&o.InputRef)
		resolver.resolveReference(&o.OutputRef)

		// Resolve references for errors also
		for i := range o.ErrorRefs {
			resolver.resolveReference(&o.ErrorRefs[i])
			o.ErrorRefs[i].Shape.Exception = true
			o.ErrorRefs[i].Shape.ErrorInfo.Type = o.ErrorRefs[i].Shape.ShapeName
		}
	}
}

func (a *API) backfillErrorMembers() {
	stubShape := &Shape{
		ShapeName: "string",
		Type:      "string",
	}
	var locName string
	switch a.Metadata.Protocol {
	case "ec2", "query", "rest-xml":
		locName = "Message"
	case "json", "rest-json":
		locName = "message"
	}

	for _, s := range a.Shapes {
		if !s.Exception {
			continue
		}

		var haveMessage bool
		for name := range s.MemberRefs {
			if strings.EqualFold(name, "Message") {
				haveMessage = true
				break
			}
		}
		if !haveMessage {
			ref := &ShapeRef{
				ShapeName:    stubShape.ShapeName,
				Shape:        stubShape,
				LocationName: locName,
			}
			s.MemberRefs["Message"] = ref
			stubShape.Refs = append(stubShape.Refs, ref)
		}
	}

	if len(stubShape.Refs) != 0 {
		a.Shapes["SDKStubErrorMessageShape"] = stubShape
	}
}

// A referenceResolver provides a way to resolve shape references to
// shape definitions.
type referenceResolver struct {
	*API
	visited map[*ShapeRef]bool
}

// resolveReference updates a shape reference to reference the API and
// its shape definition. All other nested references are also resolved.
func (r *referenceResolver) resolveReference(ref *ShapeRef) {
	if ref.ShapeName == "" {
		return
	}

	shape, ok := r.API.Shapes[ref.ShapeName]
	if !ok {
		panic(fmt.Sprintf("unable resolve reference, %s", ref.ShapeName))
	}

	if ref.JSONValue {
		if err := setTargetAsJSONValue(r.API, "", "", ref); err != nil {
			panic(fmt.Sprintf("failed to set reference as JSONValue, %v", err))
		}
	}

	ref.API = r.API   // resolve reference back to API
	ref.Shape = shape // resolve shape reference

	if r.visited[ref] {
		return
	}
	r.visited[ref] = true

	shape.Refs = append(shape.Refs, ref) // register the ref

	// resolve shape's references, if it has any
	r.resolveShape(shape)
}

func setTargetAsJSONValue(a *API, parentName, refName string, ref *ShapeRef) error {
	ref.ShapeName = "JSONValue"
	if _, ok := a.Shapes[ref.ShapeName]; !ok {
		a.Shapes[ref.ShapeName] = &Shape{
			API:       a,
			ShapeName: "JSONValue",
			Type:      "jsonvalue",
			ValueRef: ShapeRef{
				JSONValue: true,
			},
		}
	}
	return nil
}

// resolveShape resolves a shape's Member Key Value, and nested member
// shape references.
func (r *referenceResolver) resolveShape(shape *Shape) {
	r.resolveReference(&shape.MemberRef)
	r.resolveReference(&shape.KeyRef)
	r.resolveReference(&shape.ValueRef)
	for _, m := range shape.MemberRefs {
		r.resolveReference(m)
	}
}

// fixStutterNames fixes all name stuttering based on Go naming conventions.
// "Stuttering" is when the prefix of a structure or function matches the
// package name (case insensitive).
func (a *API) fixStutterNames() {
	names, ok := legacyStutterNames[ServiceID(a)]
	if !ok {
		return
	}

	shapeNames := names.ShapeOrder
	if len(shapeNames) == 0 {
		shapeNames = make([]string, 0, len(names.Shapes))
		for k := range names.Shapes {
			shapeNames = append(shapeNames, k)
		}
	}

	for _, shapeName := range shapeNames {
		s := a.Shapes[shapeName]
		newName := names.Shapes[shapeName]
		if other, ok := a.Shapes[newName]; ok && (other.Type == "structure" || other.Type == "enum") {
			panic(fmt.Sprintf(
				"shape name already exists, renaming %v to %v\n",
				s.ShapeName, newName))
		}
		s.Rename(newName)
	}

	for opName, newName := range names.Operations {
		if _, ok := a.Operations[newName]; ok {
			panic(fmt.Sprintf(
				"operation name already exists, renaming %v to %v\n",
				opName, newName))
		}
		op := a.Operations[opName]
		delete(a.Operations, opName)
		a.Operations[newName] = op
		op.ExportedName = newName
	}
}

// regexpForValidatingShapeName is used by validateShapeName to filter acceptable shape names
// that may be renamed to a new valid shape name, if not already.
// The regex allows underscores(_) at the beginning of the shape name
// There may be 0 or more underscores(_). The next character would be the leading character
// in the renamed shape name and thus, must be an alphabetic character.
// The regex allows alphanumeric characters along with underscores(_) in rest of the string.
var regexForValidatingShapeName = regexp.MustCompile("^[_]*[a-zA-Z][a-zA-Z0-9_]*$")

// legacyShapeNames is a map of shape names that are supported and bypass the validateShapeNames util
var legacyShapeNames = map[string][]string{
	"mediapackage": {
		"__AdTriggersElement",
		"__PeriodTriggersElement",
	},
}

// validateShapeNames is valid only for shapes of type structure or enums
// We validate a shape name to check if its a valid shape name
// A valid shape name would only contain alphanumeric characters and have an alphabet as leading character.
//
// If we encounter a shape name with underscores(_), we remove the underscores, and
// follow a canonical upper camel case naming scheme to create a new shape name.
// If the shape name collides with an existing shape name we return an error.
// The resulting shape name must be a valid shape name or throw an error.
func (a *API) validateShapeNames() error {
loop:
	for _, s := range a.Shapes {
		if s.Type == "structure" || s.IsEnum() {
			for _, legacyname := range legacyShapeNames[a.PackageName()] {
				if s.ShapeName == legacyname {
					continue loop
				}
			}
			name := s.ShapeName
			if b := regexForValidatingShapeName.MatchString(name); !b {
				return fmt.Errorf("invalid shape name found: %v", s.ShapeName)
			}

			// Slice of strings returned after we split a string
			// with a non alphanumeric character as delimiter.
			slice := strings.FieldsFunc(name, func(r rune) bool {
				return !unicode.IsLetter(r) && !unicode.IsNumber(r)
			})

			// Build a string that follows canonical upper camel casing
			var b strings.Builder
			for _, word := range slice {
				b.WriteString(strings.Title(word))
			}

			name = b.String()
			if s.ShapeName != name {
				if a.Shapes[name] != nil {
					// throw an error if shape with a new shape name already exists
					return fmt.Errorf("attempt to rename shape %v to %v for package %v failed, as this rename would result in shape name collision",
						s.ShapeName, name, a.PackageName())
				}
				debugLogger.Logf("Renaming shape %v to %v for package %v \n", s.ShapeName, name, a.PackageName())
				s.Rename(name)
			}
		}
	}
	return nil
}

// renameExportable renames all operation names to be exportable names.
// All nested Shape names are also updated to the exportable variant.
func (a *API) renameExportable() {
	for name, op := range a.Operations {
		newName := a.ExportableName(name)
		if newName != name {
			delete(a.Operations, name)
			a.Operations[newName] = op
		}
		op.ExportedName = newName
	}

	for k, s := range a.Shapes {
		// FIXME SNS has lower and uppercased shape names with the same name,
		// except the lowercased variant is used exclusively for string and
		// other primitive types. Renaming both would cause a collision.
		// We work around this by only renaming the structure shapes.
		if s.Type == "string" {
			continue
		}

		for mName, member := range s.MemberRefs {
			newName := a.ExportableName(mName)
			if newName != mName {
				delete(s.MemberRefs, mName)
				s.MemberRefs[newName] = member

				// also apply locationName trait so we keep the old one
				// but only if there's no locationName trait on ref or shape
				if member.LocationName == "" && member.Shape.LocationName == "" {
					member.LocationName = mName
				}
			}
			member.OriginalMemberName = mName

			if newName == "_" {
				panic("Shape " + s.ShapeName + " uses reserved member name '_'")
			}
		}

		newName := a.ExportableName(k)
		if s.Type == "structure" && newName == a.StructName() {
			// If struct collides client's struct type name the shape needs to
			// be renamed with a trailing `_` to prevent collision.
			newName += "_"
		}

		if newName != s.ShapeName {
			s.Rename(newName)
		}

		s.Payload = a.ExportableName(s.Payload)

		// fix required trait names
		for i, n := range s.Required {
			s.Required[i] = a.ExportableName(n)
		}
	}

	for _, s := range a.Shapes {
		// fix enum names
		if s.IsEnum() {
			s.EnumConsts = make([]string, len(s.Enum))
			for i := range s.Enum {
				shape := s.ShapeName
				shape = strings.ToUpper(shape[0:1]) + shape[1:]
				s.EnumConsts[i] = shape + s.EnumName(i)
			}
		}
	}
}

// renameCollidingFields will rename any fields that uses an SDK or Golang
// specific name.
func (a *API) renameCollidingFields() {
	for _, v := range a.Shapes {
		namesWithSet := map[string]struct{}{}
		for k, field := range v.MemberRefs {
			if _, ok := v.MemberRefs["Set"+k]; ok {
				namesWithSet["Set"+k] = struct{}{}
			}

			if collides(k) || (v.Exception && exceptionCollides(k)) {
				renameCollidingField(k, v, field)
			}
		}

		// checks if any field names collide with setters.
		for name := range namesWithSet {
			field := v.MemberRefs[name]
			renameCollidingField(name, v, field)
		}
	}
}

func renameCollidingField(name string, v *Shape, field *ShapeRef) {
	newName := name + "_"
	debugLogger.Logf("Shape %s's field %q renamed to %q", v.ShapeName, name, newName)
	delete(v.MemberRefs, name)
	v.MemberRefs[newName] = field
	// Set LocationName to the original field name if it is not already set.
	// This is to ensure we correctly serialize to the proper member name
	if len(field.LocationName) == 0 {
		field.LocationName = name
	}
}

// collides will return true if it is a name used by the SDK or Golang.
func collides(name string) bool {
	switch name {
	case "String",
		"GoString",
		"Validate":
		return true
	}
	return false
}

func exceptionCollides(name string) bool {
	switch name {
	case "Code",
		"Message",
		"OrigErr",
		"Error",
		"String",
		"GoString",
		"RequestID",
		"StatusCode",
		"RespMetadata":
		return true
	}
	return false
}

func (a *API) applyShapeNameAliases() {
	service, ok := shapeNameAliases[a.name]
	if !ok {
		return
	}

	// Generic Shape Aliases
	for name, s := range a.Shapes {
		if alias, ok := service[name]; ok {
			s.Rename(alias)
			s.AliasedShapeName = true
		}
	}
}

// renameIOSuffixedShapeNames renames shapes that have `Input` or `Output`
// as suffix in their shape names. We add `_` and the end to avoid possible
// conflicts with the generated operation input/output types. SDK has already
// released quite a few shapes with input, output name suffixed with Input or Output.
// This change uses a legacy IO suffixed list and does not rename those legacy shapes.
// We do not rename aliased shapes. We do not rename shapes that are an input or output
// shape of an operation.
func (a *API) renameIOSuffixedShapeNames() {
	// map all input shapes in service enclosure
	inputShapes := make(map[string]*Shape, len(a.Operations))

	// map all output shapes in service enclosure
	outputShapes := make(map[string]*Shape, len(a.Operations))

	for _, op := range a.Operations {
		if len(op.InputRef.ShapeName) != 0 {
			inputShapes[op.InputRef.Shape.ShapeName] = op.InputRef.Shape
		}

		if len(op.OutputRef.ShapeName) != 0 {
			outputShapes[op.OutputRef.Shape.ShapeName] = op.OutputRef.Shape
		}
	}

	for name, shape := range a.Shapes {
		// skip if this shape is already aliased
		if shape.AliasedShapeName {
			continue
		}

		// skip if shape name is not suffixed with `Input` or `Output`
		if !strings.HasSuffix(name, "Input") && !strings.HasSuffix(name, "Output") {
			continue
		}

		// skip if this shape is an input shape
		if s, ok := inputShapes[name]; ok && s == shape {
			continue
		}

		// skip if this shape is an output shape
		if s, ok := outputShapes[name]; ok && s == shape {
			continue
		}

		// skip if this shape is a legacy io suffixed shape
		if legacyIOSuffixed.LegacyIOSuffix(a, name) {
			continue
		}

		// rename the shape to suffix with `_`
		shape.Rename(name + "_")
	}
}

// createInputOutputShapes creates toplevel input/output shapes if they
// have not been defined in the API. This normalizes all APIs to always
// have an input and output structure in the signature.
func (a *API) createInputOutputShapes() {
	for _, op := range a.Operations {
		createAPIParamShape(a, op.Name, &op.InputRef, op.ExportedName+"Input",
			shamelist.Input,
		)
		op.InputRef.Shape.UsedAsInput = true

		createAPIParamShape(a, op.Name, &op.OutputRef, op.ExportedName+"Output",
			shamelist.Output,
		)
		op.OutputRef.Shape.UsedAsOutput = true
	}
}

func (a *API) renameAPIPayloadShapes() {
	for _, op := range a.Operations {
		op.InputRef.Payload = a.ExportableName(op.InputRef.Payload)
		op.OutputRef.Payload = a.ExportableName(op.OutputRef.Payload)
	}
}

func createAPIParamShape(a *API, opName string, ref *ShapeRef, shapeName string, shamelistLookup func(string, string) bool) {
	if len(ref.ShapeName) == 0 {
		setAsPlacholderShape(ref, shapeName, a)
		return
	}

	// nothing to do if already the correct name.
	if s := ref.Shape; s.AliasedShapeName || s.ShapeName == shapeName || shamelistLookup(a.name, opName) {
		return
	}


	if s, ok := a.Shapes[shapeName]; ok {
		panic(fmt.Sprintf(
			"attempting to create duplicate API parameter shape, %v, %v, %v, %v\n",
			shapeName, opName, ref.ShapeName, s.OrigShapeName,
		))
	}

	ref.Shape.removeRef(ref)
	ref.ShapeName = shapeName
	ref.Shape = ref.Shape.Clone(shapeName)
	ref.Shape.Refs = append(ref.Shape.Refs, ref)
}

func setAsPlacholderShape(tgtShapeRef *ShapeRef, name string, a *API) {
	shape := a.makeIOShape(name)
	shape.Placeholder = true
	*tgtShapeRef = ShapeRef{API: a, ShapeName: shape.ShapeName, Shape: shape}
	shape.Refs = append(shape.Refs, tgtShapeRef)
}

// makeIOShape returns a pointer to a new Shape initialized by the name provided.
func (a *API) makeIOShape(name string) *Shape {
	shape := &Shape{
		API: a, ShapeName: name, Type: "structure",
		MemberRefs: map[string]*ShapeRef{},
	}
	a.Shapes[name] = shape
	return shape
}

// removeUnusedShapes removes shapes from the API which are not referenced by
// any other shape in the API.
func (a *API) removeUnusedShapes() {
	for _, s := range a.Shapes {
		if len(s.Refs) == 0 {
			a.removeShape(s)
		}
	}
}

// Sets the EndpointsID field of Metadata  with the value of the
// EndpointPrefix if EndpointsID is not set.
func (a *API) setMetadataEndpointsKey() {
	if len(a.Metadata.EndpointsID) != 0 {
		return
	}
	a.Metadata.EndpointsID = a.Metadata.EndpointPrefix
}

func (a *API) findEndpointDiscoveryOp() {
	for _, op := range a.Operations {
		if op.IsEndpointDiscoveryOp {
			a.EndpointDiscoveryOp = op
			return
		}
	}
}

func (a *API) injectUnboundedOutputStreaming() {
	for _, op := range a.Operations {
		if op.AuthType != V4UnsignedBodyAuthType {
			continue
		}
		for _, ref := range op.InputRef.Shape.MemberRefs {
			if ref.Streaming || ref.Shape.Streaming {
				if len(ref.Documentation) != 0 {
					ref.Documentation += `
//`
				}
				ref.Documentation += `
// To use an non-seekable io.Reader for this request wrap the io.Reader with
// "aws.ReadSeekCloser". The SDK will not retry request errors for non-seekable
// readers. This will allow the SDK to send the reader's payload as chunked
// transfer encoding.`
			}
		}
	}
}
