package flag

import (
	"context"
	"errors"
	"fmt"
	"strconv"
	"strings"

	cosmos_proto "github.com/cosmos/cosmos-proto"
	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/reflect/protodesc"
	"google.golang.org/protobuf/reflect/protoreflect"
	"google.golang.org/protobuf/reflect/protoregistry"

	autocliv1 "cosmossdk.io/api/cosmos/autocli/v1"
	msgv1 "cosmossdk.io/api/cosmos/msg/v1"
	"cosmossdk.io/client/v2/internal/flags"
	"cosmossdk.io/client/v2/internal/util"
	"cosmossdk.io/core/address"
)

const (
	AddressStringScalarType          = "cosmos.AddressString"
	ValidatorAddressStringScalarType = "cosmos.ValidatorAddressString"
	ConsensusAddressStringScalarType = "cosmos.ConsensusAddressString"
	PubkeyScalarType                 = "cosmos.Pubkey"
	DecScalarType                    = "cosmos.Dec"
)

// Builder manages options for building pflag flags for protobuf messages.
type Builder struct {
	// TypeResolver specifies how protobuf types will be resolved. If it is
	// nil protoregistry.GlobalTypes will be used.
	TypeResolver interface {
		protoregistry.MessageTypeResolver
		protoregistry.ExtensionTypeResolver
	}

	// FileResolver specifies how protobuf file descriptors will be resolved. If it is
	// nil protoregistry.GlobalFiles will be used.
	FileResolver interface {
		protodesc.Resolver
		RangeFiles(func(protoreflect.FileDescriptor) bool)
	}

	messageFlagTypes map[protoreflect.FullName]Type
	scalarFlagTypes  map[string]Type

	// Address Codecs are the address codecs to use for client/v2.
	AddressCodec          address.Codec
	ValidatorAddressCodec address.ValidatorAddressCodec
	ConsensusAddressCodec address.ConsensusAddressCodec
}

func (b *Builder) init() {
	if b.messageFlagTypes == nil {
		b.messageFlagTypes = map[protoreflect.FullName]Type{}
		b.messageFlagTypes["google.protobuf.Timestamp"] = timestampType{}
		b.messageFlagTypes["google.protobuf.Duration"] = durationType{}
		b.messageFlagTypes["cosmos.base.v1beta1.Coin"] = coinType{}
		b.messageFlagTypes["cosmos.base.v1beta1.DecCoin"] = decCoinType{}
	}

	if b.scalarFlagTypes == nil {
		b.scalarFlagTypes = map[string]Type{}
		b.scalarFlagTypes[AddressStringScalarType] = addressStringType{}
		b.scalarFlagTypes[ValidatorAddressStringScalarType] = validatorAddressStringType{}
		b.scalarFlagTypes[ConsensusAddressStringScalarType] = consensusAddressStringType{}
		b.scalarFlagTypes[PubkeyScalarType] = pubkeyType{}
		b.scalarFlagTypes[DecScalarType] = decType{}
	}
}

// ValidateAndComplete the flag builder fields.
// It returns an error if any of the required fields are missing.
// If the keyring is nil, it will be set to a no keyring.
func (b *Builder) ValidateAndComplete() error {
	if b.AddressCodec == nil {
		return errors.New("address codec is required in flag builder")
	}

	if b.ValidatorAddressCodec == nil {
		return errors.New("validator address codec is required in flag builder")
	}

	if b.ConsensusAddressCodec == nil {
		return errors.New("consensus address codec is required in flag builder")
	}

	if b.TypeResolver == nil {
		return errors.New("type resolver is required in flag builder")
	}

	if b.FileResolver == nil {
		return errors.New("file resolver is required in flag builder")
	}

	return nil
}

// DefineMessageFlagType allows to extend custom protobuf message type handling for flags (and positional arguments).
func (b *Builder) DefineMessageFlagType(messageName protoreflect.FullName, flagType Type) {
	b.init()
	b.messageFlagTypes[messageName] = flagType
}

// DefineScalarFlagType allows to extend custom scalar type handling for flags (and positional arguments).
func (b *Builder) DefineScalarFlagType(scalarName string, flagType Type) {
	b.init()
	b.scalarFlagTypes[scalarName] = flagType
}

// AddMessageFlags adds flags for each field in the message to the flag set.
func (b *Builder) AddMessageFlags(ctx *context.Context, flagSet *pflag.FlagSet, messageType protoreflect.MessageType, commandOptions *autocliv1.RpcCommandOptions) (*MessageBinder, error) {
	return b.addMessageFlags(ctx, flagSet, messageType, commandOptions, namingOptions{})
}

// addMessageFlags adds flags for each field in the message to the flag set.
func (b *Builder) addMessageFlags(ctx *context.Context, flagSet *pflag.FlagSet, messageType protoreflect.MessageType, commandOptions *autocliv1.RpcCommandOptions, options namingOptions) (*MessageBinder, error) {
	messageBinder := &MessageBinder{
		messageType: messageType,
		// positional args are also parsed using a FlagSet so that we can reuse all the same parsers
		positionalFlagSet: pflag.NewFlagSet("positional", pflag.ContinueOnError),
	}

	fields := messageType.Descriptor().Fields()
	signerFieldName := GetSignerFieldName(messageType.Descriptor())

	isPositional := map[string]bool{}

	positionalArgsLen := len(commandOptions.PositionalArgs)
	for i, arg := range commandOptions.PositionalArgs {
		isPositional[arg.ProtoField] = true

		// verify if a positional field is a signer field
		if arg.ProtoField == signerFieldName {
			messageBinder.SignerInfo = SignerInfo{
				PositionalArgIndex: i,
				FieldName:          arg.ProtoField,
			}
		}

		if arg.Optional && arg.Varargs {
			return nil, fmt.Errorf("positional argument %s can't be both optional and varargs", arg.ProtoField)
		}

		if arg.Varargs {
			if i != positionalArgsLen-1 {
				return nil, fmt.Errorf("varargs positional argument %s must be the last argument", arg.ProtoField)
			}

			messageBinder.hasVarargs = true
		}

		if arg.Optional {
			if i != positionalArgsLen-1 {
				return nil, fmt.Errorf("optional positional argument %s must be the last argument", arg.ProtoField)
			}

			messageBinder.hasOptional = true
		}

		s := strings.Split(arg.ProtoField, ".")
		if len(s) == 1 {
			f, err := b.addFieldBindingToArgs(ctx, messageBinder, protoreflect.Name(arg.ProtoField), fields)
			if err != nil {
				return nil, err
			}
			messageBinder.positionalArgs = append(messageBinder.positionalArgs, f)
		} else {
			err := b.addFlattenFieldBindingToArgs(ctx, arg.ProtoField, s, messageType, messageBinder)
			if err != nil {
				return nil, err
			}
		}
	}

	totalArgs := len(messageBinder.positionalArgs)
	switch {
	case messageBinder.hasVarargs:
		messageBinder.CobraArgs = cobra.MinimumNArgs(totalArgs - 1)
		messageBinder.mandatoryArgUntil = totalArgs - 1
	case messageBinder.hasOptional:
		messageBinder.CobraArgs = cobra.RangeArgs(totalArgs-1, totalArgs)
		messageBinder.mandatoryArgUntil = totalArgs - 1
	default:
		messageBinder.CobraArgs = cobra.ExactArgs(totalArgs)
		messageBinder.mandatoryArgUntil = totalArgs
	}

	// validate flag options
	for name, opts := range commandOptions.FlagOptions {
		if fields.ByName(protoreflect.Name(name)) == nil {
			return nil, fmt.Errorf("can't find field %s on %s specified as a flag", name, messageType.Descriptor().FullName())
		}

		// verify if a flag is a signer field
		if name == signerFieldName {
			messageBinder.SignerInfo = SignerInfo{
				FieldName: name,
				IsFlag:    true,
				FlagName:  opts.Name,
			}
		}
	}

	// if signer has not been specified as positional arguments,
	// add it as `--from` flag (instead of --field-name flags)
	if signerFieldName != "" && messageBinder.SignerInfo == (SignerInfo{}) {
		if commandOptions.FlagOptions == nil {
			commandOptions.FlagOptions = make(map[string]*autocliv1.FlagOptions)
		}

		commandOptions.FlagOptions[signerFieldName] = &autocliv1.FlagOptions{
			Name:      flags.FlagFrom,
			Usage:     "Name or address with which to sign the message",
			Shorthand: "f",
		}

		messageBinder.SignerInfo = SignerInfo{
			FieldName: signerFieldName,
			IsFlag:    true,
			FlagName:  flags.FlagFrom,
		}
	}

	// define all other fields as flags
	flagOptsByFlagName := map[string]*autocliv1.FlagOptions{}
	for i := 0; i < fields.Len(); i++ {
		field := fields.Get(i)
		fieldName := string(field.Name())

		// skips positional args and signer field if already set
		if isPositional[fieldName] ||
			(fieldName == signerFieldName && messageBinder.SignerInfo.FlagName == flags.FlagFrom) {
			continue
		}

		flagOpts := commandOptions.FlagOptions[fieldName]
		name, hasValue, err := b.addFieldFlag(ctx, flagSet, field, flagOpts, options)
		if err != nil {
			return nil, err
		}
		flagOptsByFlagName[name] = flagOpts

		messageBinder.flagBindings = append(messageBinder.flagBindings, fieldBinding{
			hasValue: hasValue,
			field:    field,
		})
	}

	flagSet.VisitAll(func(flag *pflag.Flag) {
		opts := flagOptsByFlagName[flag.Name]
		if opts != nil {
			// This is a bit of hacking around the pflag API, but
			// we need to set these options here using Flag.VisitAll because the flag
			// constructors that pflag gives us (StringP, Int32P, etc.) do not
			// actually return the *Flag instance
			flag.Deprecated = opts.Deprecated
			flag.ShorthandDeprecated = opts.ShorthandDeprecated
			flag.Hidden = opts.Hidden
		}
	})

	return messageBinder, nil
}

// addFlattenFieldBindingToArgs recursively adds field bindings for nested message fields to the message binder.
// It takes a slice of field names representing the path to the target field, where each element is a field name
// in the nested message structure. For example, ["foo", "bar", "baz"] would bind the "baz" field inside the "bar"
// message which is inside the "foo" message.
func (b *Builder) addFlattenFieldBindingToArgs(ctx *context.Context, path string, s []string, msg protoreflect.MessageType, messageBinder *MessageBinder) error {
	fields := msg.Descriptor().Fields()
	if len(s) == 1 {
		f, err := b.addFieldBindingToArgs(ctx, messageBinder, protoreflect.Name(s[0]), fields)
		if err != nil {
			return err
		}
		f.path = path
		messageBinder.positionalArgs = append(messageBinder.positionalArgs, f)
		return nil
	}
	fd := fields.ByName(protoreflect.Name(s[0]))
	var innerMsg protoreflect.MessageType
	if fd.IsList() {
		innerMsg = msg.New().Get(fd).List().NewElement().Message().Type()
	} else {
		innerMsg = msg.New().Get(fd).Message().Type()
	}
	return b.addFlattenFieldBindingToArgs(ctx, path, s[1:], innerMsg, messageBinder)
}

// addFieldBindingToArgs adds a fieldBinding for a positional argument to the message binder.
// The fieldBinding is appended to the positional arguments list in the message binder.
func (b *Builder) addFieldBindingToArgs(ctx *context.Context, messageBinder *MessageBinder, name protoreflect.Name, fields protoreflect.FieldDescriptors) (fieldBinding, error) {
	field := fields.ByName(name)
	if field == nil {
		return fieldBinding{}, fmt.Errorf("can't find field %s", name) // TODO: it will improve error if msg.FullName() was included.`
	}

	_, hasValue, err := b.addFieldFlag(
		ctx,
		messageBinder.positionalFlagSet,
		field,
		&autocliv1.FlagOptions{Name: fmt.Sprintf("%d", len(messageBinder.positionalArgs))},
		namingOptions{},
	)
	if err != nil {
		return fieldBinding{}, err
	}

	return fieldBinding{
		field:    field,
		hasValue: hasValue,
	}, nil
}

// bindPageRequest create a flag for pagination
func (b *Builder) bindPageRequest(ctx *context.Context, flagSet *pflag.FlagSet, field protoreflect.FieldDescriptor) (HasValue, error) {
	return b.addMessageFlags(
		ctx,
		flagSet,
		util.ResolveMessageType(b.TypeResolver, field.Message()),
		&autocliv1.RpcCommandOptions{},
		namingOptions{Prefix: "page-"},
	)
}

// namingOptions specifies internal naming options for flags.
type namingOptions struct {
	// Prefix is a prefix to prepend to all flags.
	Prefix string
}

// addFieldFlag adds a flag for the provided field to the flag set.
func (b *Builder) addFieldFlag(ctx *context.Context, flagSet *pflag.FlagSet, field protoreflect.FieldDescriptor, opts *autocliv1.FlagOptions, options namingOptions) (name string, hasValue HasValue, err error) {
	if opts == nil {
		opts = &autocliv1.FlagOptions{}
	}

	if field.Kind() == protoreflect.MessageKind && field.Message().FullName() == "cosmos.base.query.v1beta1.PageRequest" {
		hasValue, err := b.bindPageRequest(ctx, flagSet, field)
		return "", hasValue, err
	}

	name = opts.Name
	if name == "" {
		name = options.Prefix + util.DescriptorKebabName(field)
	}

	usage := opts.Usage
	shorthand := opts.Shorthand
	defaultValue := opts.DefaultValue

	if typ := b.resolveFlagType(field); typ != nil {
		if defaultValue == "" {
			defaultValue = typ.DefaultValue()
		}

		val := typ.NewValue(ctx, b)
		flagSet.AddFlag(&pflag.Flag{
			Name:      name,
			Shorthand: shorthand,
			Usage:     usage,
			DefValue:  defaultValue,
			Value:     val,
		})
		return name, val, nil
	}

	// use the built-in pflag StringP, Int32P, etc. functions
	var val HasValue

	if field.IsList() {
		val = bindSimpleListFlag(flagSet, field.Kind(), name, shorthand, usage)
	} else if field.IsMap() {
		keyKind := field.MapKey().Kind()
		valKind := field.MapValue().Kind()
		val = bindSimpleMapFlag(flagSet, keyKind, valKind, name, shorthand, usage)
	} else {
		val = bindSimpleFlag(flagSet, field.Kind(), name, shorthand, usage)
	}

	// This is a bit of hacking around the pflag API, but the
	// defaultValue is set in this way because this is much easier than trying
	// to parse the string into the types that StringSliceP, Int32P, etc.
	if defaultValue != "" {
		err = flagSet.Set(name, defaultValue)
	}

	return name, val, err
}

func (b *Builder) resolveFlagType(field protoreflect.FieldDescriptor) Type {
	typ := b.resolveFlagTypeBasic(field)
	if field.IsList() {
		if typ != nil {
			return compositeListType{simpleType: typ}
		}
		return nil
	}
	if field.IsMap() {
		keyKind := field.MapKey().Kind()
		valType := b.resolveFlagType(field.MapValue())
		if valType != nil {
			switch keyKind {
			case protoreflect.StringKind:
				ct := new(compositeMapType[string])
				ct.keyValueResolver = func(s string) (string, error) { return s, nil }
				ct.valueType = valType
				ct.keyType = "string"
				return ct
			case protoreflect.Int32Kind, protoreflect.Sint32Kind, protoreflect.Sfixed32Kind:
				ct := new(compositeMapType[int32])
				ct.keyValueResolver = func(s string) (int32, error) {
					i, err := strconv.ParseInt(s, 10, 32)
					return int32(i), err
				}
				ct.valueType = valType
				ct.keyType = "int32"
				return ct
			case protoreflect.Int64Kind, protoreflect.Sint64Kind, protoreflect.Sfixed64Kind:
				ct := new(compositeMapType[int64])
				ct.keyValueResolver = func(s string) (int64, error) {
					i, err := strconv.ParseInt(s, 10, 64)
					return i, err
				}
				ct.valueType = valType
				ct.keyType = "int64"
				return ct
			case protoreflect.Uint32Kind, protoreflect.Fixed32Kind:
				ct := new(compositeMapType[uint32])
				ct.keyValueResolver = func(s string) (uint32, error) {
					i, err := strconv.ParseUint(s, 10, 32)
					return uint32(i), err
				}
				ct.valueType = valType
				ct.keyType = "uint32"
				return ct
			case protoreflect.Uint64Kind, protoreflect.Fixed64Kind:
				ct := new(compositeMapType[uint64])
				ct.keyValueResolver = func(s string) (uint64, error) {
					i, err := strconv.ParseUint(s, 10, 64)
					return i, err
				}
				ct.valueType = valType
				ct.keyType = "uint64"
				return ct
			case protoreflect.BoolKind:
				ct := new(compositeMapType[bool])
				ct.keyValueResolver = strconv.ParseBool
				ct.valueType = valType
				ct.keyType = "bool"
				return ct
			}
			return nil

		}
		return nil
	}

	return typ
}

func (b *Builder) resolveFlagTypeBasic(field protoreflect.FieldDescriptor) Type {
	scalar, ok := GetScalarType(field)
	if ok {
		b.init()
		if typ, ok := b.scalarFlagTypes[scalar]; ok {
			return typ
		}
	}

	switch field.Kind() {
	case protoreflect.BytesKind:
		return binaryType{}
	case protoreflect.EnumKind:
		return enumType{enum: field.Enum()}
	case protoreflect.MessageKind:
		b.init()
		if flagType, ok := b.messageFlagTypes[field.Message().FullName()]; ok {
			return flagType
		}
		return jsonMessageFlagType{
			messageDesc: field.Message(),
		}
	default:
		return nil
	}
}

// GetScalarType gets scalar type of a field.
func GetScalarType(field protoreflect.FieldDescriptor) (string, bool) {
	scalar := proto.GetExtension(field.Options(), cosmos_proto.E_Scalar)
	scalarStr, ok := scalar.(string)
	return scalarStr, ok
}

// GetSignerFieldName gets signer field name of a message.
// AutoCLI supports only one signer field per message.
func GetSignerFieldName(descriptor protoreflect.MessageDescriptor) string {
	signersFields := proto.GetExtension(descriptor.Options(), msgv1.E_Signer).([]string)
	if len(signersFields) == 0 {
		return ""
	}

	return signersFields[0]
}