package runtime

import (
	"fmt"
	"reflect"
	"strings"

	"github.com/aws/jsii-runtime-go/internal/api"
	"github.com/aws/jsii-runtime-go/internal/kernel"
)

// FQN represents a fully-qualified type name in the jsii type system.
type FQN api.FQN

// Member is a runtime descriptor for a class or interface member
type Member interface {
	toOverride() api.Override
}

// MemberMethod is a runtime descriptor for a class method (implementation of Member)
type MemberMethod api.MethodOverride

func (m MemberMethod) toOverride() api.Override {
	return api.MethodOverride(m)
}

// MemberProperty is a runtime descriptor for a class or interface property (implementation of Member)
type MemberProperty api.PropertyOverride

func (m MemberProperty) toOverride() api.Override {
	return api.PropertyOverride(m)
}

// Load ensures a npm package is loaded in the jsii kernel.
func Load(name string, version string, tarball []byte) {
	c := kernel.GetClient()

	_, err := c.Load(kernel.LoadProps{
		Name:    name,
		Version: version,
	}, tarball)
	if err != nil {
		panic(err)
	}
}

// RegisterClass associates a class fully qualified name to the specified class
// interface, member list, and proxy maker function. Panics if class is not a go
// interface, or if the provided fqn was already used to register a different type.
func RegisterClass(fqn FQN, class reflect.Type, members []Member, maker func() interface{}) {
	client := kernel.GetClient()

	overrides := make([]api.Override, len(members))
	for i, m := range members {
		overrides[i] = m.toOverride()
	}

	if err := client.Types().RegisterClass(api.FQN(fqn), class, overrides, maker); err != nil {
		panic(err)
	}
}

// RegisterEnum associates an enum's fully qualified name to the specified enum
// type, and members. Panics if enum is not a reflect.String type, any value in
// the provided members map is of a type other than enum, or if the provided
// fqn was already used to register a different type.
func RegisterEnum(fqn FQN, enum reflect.Type, members map[string]interface{}) {
	client := kernel.GetClient()
	if err := client.Types().RegisterEnum(api.FQN(fqn), enum, members); err != nil {
		panic(err)
	}
}

// RegisterInterface associates an interface's fully qualified name to the
// specified interface type, member list, and proxy maker function. Panics if iface is not
// an interface, or if the provided fqn was already used to register a different type.
func RegisterInterface(fqn FQN, iface reflect.Type, members []Member, maker func() interface{}) {
	client := kernel.GetClient()

	overrides := make([]api.Override, len(members))
	for i, m := range members {
		overrides[i] = m.toOverride()
	}

	if err := client.Types().RegisterInterface(api.FQN(fqn), iface, overrides, maker); err != nil {
		panic(err)
	}
}

// RegisterStruct associates a struct's fully qualified name to the specified
// struct type. Panics if strct is not a struct, or if the provided fqn was
// already used to register a different type.
func RegisterStruct(fqn FQN, strct reflect.Type) {
	client := kernel.GetClient()
	if err := client.Types().RegisterStruct(api.FQN(fqn), strct); err != nil {
		panic(err)
	}
}

// RegisterStructValidator adds a validator function to an already registered
// struct type. This is separate call largely to maintain backwards compatibility
// with existing code.
func RegisterStructValidator(strct reflect.Type, validator func(interface{}, func() string) error) {
	client := kernel.GetClient()
	if err := client.Types().RegisterStructValidator(strct, validator); err != nil {
		panic(err)
	}
}

// InitJsiiProxy initializes a jsii proxy instance at the provided pointer.
// Panics if the pointer cannot be initialized to a proxy instance (i.e: the
// element of it is not a registered jsii interface or class type).
func InitJsiiProxy(ptr interface{}) {
	ptrVal := reflect.ValueOf(ptr).Elem()
	if err := kernel.GetClient().Types().InitJsiiProxy(ptrVal, ptrVal.Type()); err != nil {
		panic(err)
	}
}

// IsAnonymousProxy tells whether the value v is an anonymous object proxy, or
// a pointer to one.
func IsAnonymousProxy(v interface{}) bool {
	return kernel.GetClient().Types().IsAnonymousProxy(v)
}

// Create will construct a new JSII object within the kernel runtime. This is
// called by jsii object constructors.
func Create(fqn FQN, args []interface{}, inst interface{}) {
	client := kernel.GetClient()

	instVal := reflect.ValueOf(inst)
	structVal := instVal.Elem()
	instType := structVal.Type()
	numField := instType.NumField()
	for i := 0; i < numField; i++ {
		field := instType.Field(i)
		if !field.Anonymous {
			continue
		}
		switch field.Type.Kind() {
		case reflect.Interface:
			fieldVal := structVal.Field(i)
			if !fieldVal.IsNil() {
				continue
			}
			if err := client.Types().InitJsiiProxy(fieldVal, fieldVal.Type()); err != nil {
				panic(err)
			}

		case reflect.Struct:
			fieldVal := structVal.Field(i)
			if !fieldVal.IsZero() {
				continue
			}
			if err := client.Types().InitJsiiProxy(fieldVal, fieldVal.Type()); err != nil {
				panic(err)
			}
		}
	}

	// Find method overrides thru reflection
	mOverrides := getMethodOverrides(inst, "jsiiProxy_")
	// If overriding struct has no overriding methods, could happen if
	// overriding methods are not defined with pointer receiver.
	if len(mOverrides) == 0 && !strings.HasPrefix(instType.Name(), "jsiiProxy_") {
		panic(fmt.Errorf("%v has no overriding methods. Overriding methods must be defined with a pointer receiver", instType.Name()))
	}
	var overrides []api.Override
	registry := client.Types()
	added := make(map[string]bool)
	for _, name := range mOverrides {
		// Use getter's name even if setter is overriden
		if strings.HasPrefix(name, "Set") {
			propName := name[3:]
			if override, ok := registry.GetOverride(api.FQN(fqn), propName); ok {
				if !added[propName] {
					added[propName] = true
					overrides = append(overrides, override)
				}
				continue
			}
		}
		if override, ok := registry.GetOverride(api.FQN(fqn), name); ok {
			if !added[name] {
				added[name] = true
				overrides = append(overrides, override)
			}
		}
	}

	interfaces, newOverrides := client.Types().DiscoverImplementation(instType)
	overrides = append(overrides, newOverrides...)

	res, err := client.Create(kernel.CreateProps{
		FQN:        api.FQN(fqn),
		Arguments:  convertArguments(args),
		Interfaces: interfaces,
		Overrides:  overrides,
	})

	if err != nil {
		panic(err)
	}

	if err = client.RegisterInstance(instVal, api.ObjectRef{InstanceID: res.InstanceID, Interfaces: interfaces}); err != nil {
		panic(err)
	}
}

// Invoke will call a method on a jsii class instance. The response will be
// decoded into the expected return type for the method being called.
func Invoke(obj interface{}, method string, args []interface{}, ret interface{}) {
	client := kernel.GetClient()

	// Find reference to class instance in client
	ref, found := client.FindObjectRef(reflect.ValueOf(obj))

	if !found {
		panic("No Object Found")
	}

	res, err := client.Invoke(kernel.InvokeProps{
		Method:    method,
		Arguments: convertArguments(args),
		ObjRef:    ref,
	})

	if err != nil {
		panic(err)
	}

	client.CastAndSetToPtr(ret, res.Result)
}

// InvokeVoid will call a void method on a jsii class instance.
func InvokeVoid(obj interface{}, method string, args []interface{}) {
	client := kernel.GetClient()

	// Find reference to class instance in client
	ref, found := client.FindObjectRef(reflect.ValueOf(obj))

	if !found {
		panic("No Object Found")
	}

	_, err := client.Invoke(kernel.InvokeProps{
		Method:    method,
		Arguments: convertArguments(args),
		ObjRef:    ref,
	})

	if err != nil {
		panic(err)
	}
}

// StaticInvoke will call a static method on a given jsii class. The response
// will be decoded into the expected return type for the method being called.
func StaticInvoke(fqn FQN, method string, args []interface{}, ret interface{}) {
	client := kernel.GetClient()

	res, err := client.SInvoke(kernel.StaticInvokeProps{
		FQN:       api.FQN(fqn),
		Method:    method,
		Arguments: convertArguments(args),
	})

	if err != nil {
		panic(err)
	}

	client.CastAndSetToPtr(ret, res.Result)
}

// StaticInvokeVoid will call a static void method on a given jsii class.
func StaticInvokeVoid(fqn FQN, method string, args []interface{}) {
	client := kernel.GetClient()

	_, err := client.SInvoke(kernel.StaticInvokeProps{
		FQN:       api.FQN(fqn),
		Method:    method,
		Arguments: convertArguments(args),
	})

	if err != nil {
		panic(err)
	}
}

// Get reads a property value on a given jsii class instance. The response
// should be decoded into the expected type of the property being read.
func Get(obj interface{}, property string, ret interface{}) {
	client := kernel.GetClient()

	// Find reference to class instance in client
	ref, found := client.FindObjectRef(reflect.ValueOf(obj))

	if !found {
		panic(fmt.Errorf("no object reference found for %v", obj))
	}

	res, err := client.Get(kernel.GetProps{
		Property: property,
		ObjRef:   ref,
	})

	if err != nil {
		panic(err)
	}

	client.CastAndSetToPtr(ret, res.Value)
}

// StaticGet reads a static property value on a given jsii class. The response
// should be decoded into the expected type of the property being read.
func StaticGet(fqn FQN, property string, ret interface{}) {
	client := kernel.GetClient()

	res, err := client.SGet(kernel.StaticGetProps{
		FQN:      api.FQN(fqn),
		Property: property,
	})

	if err != nil {
		panic(err)
	}

	client.CastAndSetToPtr(ret, res.Value)
}

// Set writes a property on a given jsii class instance. The value should match
// the type of the property being written, or the jsii kernel will crash.
func Set(obj interface{}, property string, value interface{}) {
	client := kernel.GetClient()

	// Find reference to class instance in client
	ref, found := client.FindObjectRef(reflect.ValueOf(obj))

	if !found {
		panic("No Object Found")
	}

	_, err := client.Set(kernel.SetProps{
		Property: property,
		Value:    client.CastPtrToRef(reflect.ValueOf(value)),
		ObjRef:   ref,
	})

	if err != nil {
		panic(err)
	}
}

// StaticSet writes a static property on a given jsii class. The value should
// match the type of the property being written, or the jsii kernel will crash.
func StaticSet(fqn FQN, property string, value interface{}) {
	client := kernel.GetClient()

	_, err := client.SSet(kernel.StaticSetProps{
		FQN:      api.FQN(fqn),
		Property: property,
		Value:    client.CastPtrToRef(reflect.ValueOf(value)),
	})

	if err != nil {
		panic(err)
	}
}

// convertArguments turns an argument struct and produces a list of values
// ready for inclusion in an invoke or create request.
func convertArguments(args []interface{}) []interface{} {
	if len(args) == 0 {
		return nil
	}

	result := make([]interface{}, len(args))
	client := kernel.GetClient()
	for i, arg := range args {
		val := reflect.ValueOf(arg)
		result[i] = client.CastPtrToRef(val)
	}

	return result
}

// Get ptr's methods names which override "base" struct methods.
// The "base" struct is identified by name prefix "basePrefix".
func getMethodOverrides(ptr interface{}, basePrefix string) (methods []string) {
	// Methods override cache: [methodName]bool
	mCache := make(map[string]bool)
	getMethodOverridesRec(ptr, basePrefix, mCache)
	// Return overriden methods names in embedding hierarchy
	for m := range mCache {
		methods = append(methods, m)
	}
	return
}

func getMethodOverridesRec(ptr interface{}, basePrefix string, cache map[string]bool) {
	ptrType := reflect.TypeOf(ptr)
	if ptrType.Kind() != reflect.Ptr {
		return
	}
	structType := ptrType.Elem()
	if structType.Kind() != reflect.Struct {
		return
	}
	if strings.HasPrefix(structType.Name(), basePrefix) {
		// Skip base class
		return
	}

	ptrVal := reflect.ValueOf(ptr)
	structVal := ptrVal.Elem()

	// Add embedded/super overrides first
	for i := 0; i < structType.NumField(); i++ {
		field := structType.Field(i)
		if !field.Anonymous {
			continue
		}
		if field.Type.Kind() == reflect.Ptr ||
			field.Type.Kind() == reflect.Interface {
			p := structVal.Field(i)
			if !p.IsNil() {
				getMethodOverridesRec(p.Interface(), basePrefix, cache)
			}
		}
	}
	// Add overrides in current struct
	// Current struct's value-type method-set
	valMethods := make(map[string]bool)
	for i := 0; i < structType.NumMethod(); i++ {
		valMethods[structType.Method(i).Name] = true
	}
	// Compare current struct's pointer-type method-set to its value-type method-set
	for i := 0; i < ptrType.NumMethod(); i++ {
		mn := ptrType.Method(i).Name
		if !valMethods[mn] {
			cache[mn] = true
		}
	}
}