package eip712

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"math/big"
	"reflect" // #nosec G702
	"strings"
	"time"

	errorsmod "cosmossdk.io/errors"
	sdkmath "cosmossdk.io/math"
	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
	"github.com/cosmos/cosmos-sdk/crypto/keys/ed25519"
	sdk "github.com/cosmos/cosmos-sdk/types"
	errortypes "github.com/cosmos/cosmos-sdk/types/errors"
	"golang.org/x/text/cases"
	"golang.org/x/text/language"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/math"
	"github.com/ethereum/go-ethereum/signer/core/apitypes"
)

// WrapTxToTypedData is an ultimate method that wraps Amino-encoded Cosmos Tx JSON data
// into an EIP712-compatible TypedData request.
func WrapTxToTypedData(
	cdc codectypes.AnyUnpacker,
	chainID uint64,
	msg sdk.Msg,
	data []byte,
	feeDelegation *FeeDelegationOptions,
) (apitypes.TypedData, error) {

	domain := apitypes.TypedDataDomain{
		Name:              "Cosmos Web3",
		Version:           "1.0.0",
		ChainId:           math.NewHexOrDecimal256(int64(chainID)),
		VerifyingContract: "cosmos",
		Salt:              "0",
	}

	msgTypes, err := extractMsgTypes(cdc, "MsgValue", msg)
	if err != nil {
		return apitypes.TypedData{}, err
	}

	txData := make(map[string]interface{})
	if err := json.Unmarshal(data, &txData); err != nil {
		return apitypes.TypedData{}, errorsmod.Wrap(errortypes.ErrJSONUnmarshal, "failed to JSON unmarshal data")
	}

	if err := patchTxData(txData, msgTypes, "Tx"); err != nil {
		return apitypes.TypedData{}, errorsmod.Wrap(errortypes.ErrJSONUnmarshal, "failed to patch JSON data")
	}

	if feeDelegation != nil {
		feeInfo, ok := txData["fee"].(map[string]interface{})
		if !ok {
			return apitypes.TypedData{}, errorsmod.Wrap(errortypes.ErrInvalidType, "cannot parse fee from tx data")
		}

		feeInfo["feePayer"] = feeDelegation.FeePayer.String()

		// also patching msgTypes to include feePayer
		msgTypes["Fee"] = []apitypes.Type{
			{Name: "feePayer", Type: "string"},
			{Name: "amount", Type: "Coin[]"},
			{Name: "gas", Type: "string"},
		}
	}

	typedData := apitypes.TypedData{
		Types:       msgTypes,
		PrimaryType: "Tx",
		Domain:      domain,
		Message:     txData,
	}

	return typedData, nil
}

type FeeDelegationOptions struct {
	FeePayer sdk.AccAddress
}

func extractMsgTypes(cdc codectypes.AnyUnpacker, msgTypeName string, msg sdk.Msg) (apitypes.Types, error) {
	rootTypes := apitypes.Types{
		"EIP712Domain": {
			{
				Name: "name",
				Type: "string",
			},
			{
				Name: "version",
				Type: "string",
			},
			{
				Name: "chainId",
				Type: "uint256",
			},
			{
				Name: "verifyingContract",
				Type: "string",
			},
			{
				Name: "salt",
				Type: "string",
			},
		},
		"Tx": {
			{Name: "account_number", Type: "string"},
			{Name: "chain_id", Type: "string"},
			{Name: "fee", Type: "Fee"},
			{Name: "memo", Type: "string"},
			{Name: "msgs", Type: "Msg[]"},
			{Name: "sequence", Type: "string"},
			// Note timeout_height was removed because it was not getting filled with the legacyTx
			// {Name: "timeout_height", Type: "string"},
		},
		"Fee": {
			{Name: "amount", Type: "Coin[]"},
			{Name: "gas", Type: "string"},
		},
		"Coin": {
			{Name: "denom", Type: "string"},
			{Name: "amount", Type: "string"},
		},
		"Msg": {
			{Name: "type", Type: "string"},
			{Name: "value", Type: msgTypeName},
		},
		msgTypeName: {},
	}

	if err := walkFields(cdc, rootTypes, msgTypeName, msg); err != nil {
		return nil, err
	}

	return rootTypes, nil
}

const typeDefPrefix = "_"

func walkFields(cdc codectypes.AnyUnpacker, typeMap apitypes.Types, rootType string, in interface{}) (err error) {
	defer doRecover(&err)

	t := reflect.TypeOf(in)
	v := reflect.ValueOf(in)

	for {
		if t.Kind() == reflect.Ptr ||
			t.Kind() == reflect.Interface {
			t = t.Elem()
			v = v.Elem()

			continue
		}

		break
	}

	return traverseFields(cdc, typeMap, rootType, typeDefPrefix, t, v)
}

type cosmosAnyWrapper struct {
	Type  string      `json:"type"`
	Value interface{} `json:"value"`
}

func traverseFields(
	cdc codectypes.AnyUnpacker,
	typeMap apitypes.Types,
	rootType string,
	prefix string,
	t reflect.Type,
	v reflect.Value,
) error {
	n := t.NumField()

	if prefix == typeDefPrefix {
		if len(typeMap[rootType]) == n {
			return nil
		}
	} else {
		typeDef := sanitizeTypedef(prefix)
		if len(typeMap[typeDef]) == n {
			return nil
		}
	}

	for i := 0; i < n; i++ {
		var (
			field reflect.Value
			err   error
		)

		if v.IsValid() {
			field = v.Field(i)
		}

		fieldType := t.Field(i).Type
		fieldName := jsonNameFromTag(t.Field(i).Tag)

		if fieldType == cosmosAnyType {
			// Unpack field, value as Any
			if fieldType, field, err = unpackAny(cdc, field); err != nil {
				return err
			}
		}

		// If field is an empty value, do not include in types, since it will not be present in the object
		if field.IsZero() {
			continue
		}

		// If its a nil pointer, do not include in types
		if fieldType.Kind() == reflect.Ptr && field.IsNil() {
			continue
		}

		for {
			if fieldType.Kind() == reflect.Ptr {
				fieldType = fieldType.Elem()

				if field.IsValid() {
					field = field.Elem()
				}

				continue
			}

			if fieldType.Kind() == reflect.Interface {
				fieldType = reflect.TypeOf(field.Interface())
				continue
			}

			if field.Kind() == reflect.Ptr {
				field = field.Elem()
				continue
			}

			break
		}

		var isCollection bool
		if fieldType.Kind() == reflect.Array || fieldType.Kind() == reflect.Slice {
			if field.Len() == 0 {
				// skip empty collections from type mapping
				continue
			}

			fieldType = fieldType.Elem()
			field = field.Index(0)
			isCollection = true

			if fieldType == cosmosAnyType {
				if fieldType, field, err = unpackAny(cdc, field); err != nil {
					return err
				}
			}
		}

		for {
			if fieldType.Kind() == reflect.Ptr {
				fieldType = fieldType.Elem()

				if field.IsValid() {
					field = field.Elem()
				}

				continue
			}

			if fieldType.Kind() == reflect.Interface {
				fieldType = reflect.TypeOf(field.Interface())
				continue
			}

			if field.Kind() == reflect.Ptr {
				field = field.Elem()
				continue
			}

			break
		}

		fieldPrefix := fmt.Sprintf("%s.%s", prefix, fieldName)

		ethTyp := typToEth(fieldType)
		if len(ethTyp) > 0 {
			// Support array of uint64
			if isCollection {
				if fieldType.Kind() != reflect.Slice && fieldType.Kind() != reflect.Array {
					ethTyp += "[]"
				}
				// convert uint8[] to bytes
				if fieldType.Kind() == reflect.Uint8 {
					ethTyp = "bytes"
				}
			}
			if prefix == typeDefPrefix {
				typeMap[rootType] = append(typeMap[rootType], apitypes.Type{
					Name: fieldName,
					Type: ethTyp,
				})
			} else {
				typeDef := sanitizeTypedef(prefix)
				typeMap[typeDef] = append(typeMap[typeDef], apitypes.Type{
					Name: fieldName,
					Type: ethTyp,
				})
			}

			continue
		}

		if fieldType.Kind() == reflect.Struct {
			var fieldTypedef string

			if isCollection {
				fieldTypedef = sanitizeTypedef(fieldPrefix) + "[]"
			} else {
				fieldTypedef = sanitizeTypedef(fieldPrefix)
			}

			if prefix == typeDefPrefix {
				typeMap[rootType] = append(typeMap[rootType], apitypes.Type{
					Name: fieldName,
					Type: fieldTypedef,
				})
			} else {
				typeDef := sanitizeTypedef(prefix)
				typeMap[typeDef] = append(typeMap[typeDef], apitypes.Type{
					Name: fieldName,
					Type: fieldTypedef,
				})
			}

			if err := traverseFields(cdc, typeMap, rootType, fieldPrefix, fieldType, field); err != nil {
				return err
			}

			continue
		}
	}

	return nil
}

func jsonNameFromTag(tag reflect.StructTag) string {
	jsonTags := tag.Get("json")
	parts := strings.Split(jsonTags, ",")
	return parts[0]
}

// Unpack the given Any value with Type/Value deconstruction
func unpackAny(cdc codectypes.AnyUnpacker, field reflect.Value) (reflect.Type, reflect.Value, error) {
	any, ok := field.Interface().(*codectypes.Any)
	if !ok {
		return nil, reflect.Value{}, errorsmod.Wrapf(errortypes.ErrPackAny, "%T", field.Interface())
	}

	anyWrapper := &cosmosAnyWrapper{
		Type: any.TypeUrl,
	}

	if err := cdc.UnpackAny(any, &anyWrapper.Value); err != nil {
		return nil, reflect.Value{}, errorsmod.Wrap(err, "failed to unpack Any in msg struct")
	}

	fieldType := reflect.TypeOf(anyWrapper)
	field = reflect.ValueOf(anyWrapper)

	return fieldType, field, nil
}

// _.foo_bar.baz -> TypeFooBarBaz
//
// this is needed for Geth's own signing code which doesn't
// tolerate complex type names
func sanitizeTypedef(str string) string {
	buf := new(bytes.Buffer)
	parts := strings.Split(str, ".")
	caser := cases.Title(language.English, cases.NoLower)

	for _, part := range parts {
		if part == "_" {
			buf.WriteString("Type")
			continue
		}

		subparts := strings.Split(part, "_")
		for _, subpart := range subparts {
			buf.WriteString(caser.String(subpart))
		}
	}

	return buf.String()
}

var (
	hashType      = reflect.TypeOf(common.Hash{})
	addressType   = reflect.TypeOf(common.Address{})
	bigIntType    = reflect.TypeOf(big.Int{})
	cosmIntType   = reflect.TypeOf(sdkmath.Int{})
	cosmDecType   = reflect.TypeOf(sdk.Dec{})
	cosmosAnyType = reflect.TypeOf(&codectypes.Any{})
	timeType      = reflect.TypeOf(time.Time{})

	edType = reflect.TypeOf(ed25519.PubKey{})
)

// typToEth supports only basic types and arrays of basic types.
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-712.md
func typToEth(typ reflect.Type) string {
	const str = "string"

	switch typ.Kind() {
	case reflect.String:
		return str
	case reflect.Bool:
		return "bool"
	case reflect.Int:
		return "int64"
	case reflect.Int8:
		return "int8"
	case reflect.Int16:
		return "int16"
	case reflect.Int32:
		return "int32"
	case reflect.Int64:
		return "int64"
	case reflect.Uint:
		return "uint64"
	case reflect.Uint8:
		return "uint8"
	case reflect.Uint16:
		return "uint16"
	case reflect.Uint32:
		return "uint32"
	case reflect.Uint64:
		return "uint64"
	case reflect.Slice | reflect.Array:
		// Note: this case may never be reached due to previous handling in traverseFields
		ethName := typToEth(typ.Elem())
		if len(ethName) > 0 {
			if ethName == "uint8" {
				return "bytes"
			}
			return ethName + "[]"
		}
	case reflect.Ptr:
		if typ.Elem().ConvertibleTo(bigIntType) ||
			typ.Elem().ConvertibleTo(timeType) ||
			typ.Elem().ConvertibleTo(edType) ||
			typ.Elem().ConvertibleTo(cosmDecType) ||
			typ.Elem().ConvertibleTo(cosmIntType) {
			return str
		}
	case reflect.Struct:
		if typ.ConvertibleTo(hashType) ||
			typ.ConvertibleTo(addressType) ||
			typ.ConvertibleTo(bigIntType) ||
			typ.ConvertibleTo(edType) ||
			typ.ConvertibleTo(timeType) ||
			typ.ConvertibleTo(cosmDecType) ||
			typ.ConvertibleTo(cosmIntType) {
			return str
		}
	}

	return ""
}

func doRecover(err *error) {
	if r := recover(); r != nil {
		if e, ok := r.(error); ok {
			e = errorsmod.Wrap(e, "panicked with error")
			*err = e
			return
		}

		*err = fmt.Errorf("%v", r)
	}
}

// Performs extra type conversions on JSON-decoded data accoding to the provided type definitions
// for compatibility with Geth's encoding
func patchTxData(data map[string]any, schema apitypes.Types, rootType string) error {
	// Scan the data for any types that need to be converted.
	// This is adapted from TypedData.EncodeData
	for _, field := range schema[rootType] {
		encType := field.Type
		encValue := data[field.Name]
		if encType[len(encType)-1:] == "]" {
			arrayValue, ok := encValue.([]interface{})
			if !ok {
				return dataMismatchError(encType, encValue)
			}

			parsedType := strings.Split(encType, "[")[0]
			if schema[parsedType] != nil {
				for _, item := range arrayValue {
					mapValue, ok := item.(map[string]interface{})
					if !ok {
						return dataMismatchError(parsedType, item)
					}

					err := patchTxData(mapValue, schema, parsedType)
					if err != nil {
						return err
					}
				}
			} else {
				for i, item := range arrayValue {
					converted, err := handleConversion(parsedType, item)
					if err != nil {
						return err
					}
					arrayValue[i] = converted
				}
			}

		} else if schema[encType] != nil {
			mapValue, ok := encValue.(map[string]interface{})
			if !ok {
				return dataMismatchError(encType, encValue)
			}
			err := patchTxData(mapValue, schema, encType)
			if err != nil {
				return err
			}
		} else {
			converted, err := handleConversion(encType, encValue)
			if err != nil {
				return err
			}
			data[field.Name] = converted
		}
	}
	return nil
}

func handleConversion(encType string, encValue any) (any, error) {
	switch encType {
	case "bytes":
		// Protobuf encodes byte strings in base64
		if v, ok := encValue.(string); ok {
			return base64.StdEncoding.DecodeString(v)
		}
	}
	return encValue, nil
}

// dataMismatchError generates an error for a mismatch between
// the provided type and data
func dataMismatchError(encType string, encValue any) error {
	return fmt.Errorf("provided data '%v' doesn't match type '%s'", encValue, encType)
}