// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fidl

import (
	"reflect"
	"strconv"
)

// ValidationError represents an error produced in validating a FIDL structure.
type ValidationError interface {
	error

	// Code returns the underlying ErrorCode value, which all ValidationErrors
	// must have.
	Code() ErrorCode
}

// Assert that valueError and expectError both implement the ValidationError
// interface.
var _ = []ValidationError{
	valueError{},
	expectError{},
}

// ErrorCode represents a set of machine-readable error codes each ValidationError
// has.
type ErrorCode uint32

const (
	Invalid ErrorCode = iota
	ErrUnknownOrdinal
	ErrInvalidInlineType
	ErrInvalidPointerType
	ErrVectorTooLong
	ErrStringTooLong
	ErrUnexpectedOrdinal
	ErrUnexpectedNullRef
	ErrInvalidBoolValue
	ErrNotEnoughHandles
	ErrTooManyBytesInMessage
	ErrTooManyHandles
	ErrBadHandleEncoding
	ErrNonZeroPadding
	ErrBadRefEncoding
	ErrBadInlineIndicatorEncoding
	ErrStructIsNotPayload
	ErrInvalidUnionTag
	ErrInvalidXUnionTag
	ErrInvalidBitsValue
	ErrInvalidEnumValue
	ErrPayloadTooSmall
	ErrInvalidEmptyStruct
	ErrInvalidNumBytesInEnvelope
	ErrInvalidNumHandlesInEnvelope
	ErrStringNotUTF8
	ErrUnknownMagic
	ErrMissingRequiredHandleRights
	ErrUnableToReduceHandleRights
	ErrUnspecifiedHandleRights
	ErrMissingMarshalerContext
	ErrResponseWithoutRequest
	ErrDuplicateTxidReceived
	ErrDuplicateTxidWaiting
	ErrIncorrectHandleType
	ErrUnspecifiedHandleType
	ErrValueTypeHandles
	ErrExceededMaxOutOfLineDepth
	ErrInvalidInlineBitValueInEnvelope
	ErrUnsupportedWireFormatVersion
)

var errorCodeNames = []string{
	Invalid:                            "Invalid",
	ErrUnknownOrdinal:                  "ErrUnknownOrdinal",
	ErrInvalidInlineType:               "ErrInvalidInlineType",
	ErrInvalidPointerType:              "ErrInvalidPointerType",
	ErrVectorTooLong:                   "ErrVectorTooLong",
	ErrStringTooLong:                   "ErrStringTooLong",
	ErrUnexpectedOrdinal:               "ErrUnexpectedOrdinal",
	ErrUnexpectedNullRef:               "ErrUnexpectedNullRef",
	ErrInvalidBoolValue:                "ErrInvalidBoolValue",
	ErrNotEnoughHandles:                "ErrNotEnoughHandles",
	ErrTooManyBytesInMessage:           "ErrTooManyBytesInMessage",
	ErrTooManyHandles:                  "ErrTooManyHandles",
	ErrNonZeroPadding:                  "ErrNonZeroPadding",
	ErrBadHandleEncoding:               "ErrBadHandleEncoding",
	ErrBadRefEncoding:                  "ErrBadRefEncoding",
	ErrBadInlineIndicatorEncoding:      "ErrBadInlineIndicatorEncoding",
	ErrStructIsNotPayload:              "ErrStructIsNotPayload",
	ErrInvalidUnionTag:                 "ErrInvalidUnionTag",
	ErrInvalidXUnionTag:                "ErrInvalidXUnionTag",
	ErrInvalidBitsValue:                "ErrInvalidBitsValue",
	ErrInvalidEnumValue:                "ErrInvalidEnumValue",
	ErrPayloadTooSmall:                 "ErrPayloadTooSmall",
	ErrInvalidEmptyStruct:              "ErrInvalidEmptyStruct",
	ErrInvalidNumBytesInEnvelope:       "ErrInvalidNumBytesInEnvelope",
	ErrInvalidNumHandlesInEnvelope:     "ErrInvalidNumHandlesInEnvelope",
	ErrStringNotUTF8:                   "ErrStringNotUTF8",
	ErrUnknownMagic:                    "ErrUnknownMagic",
	ErrMissingRequiredHandleRights:     "ErrMissingRequiredHandleRights",
	ErrUnableToReduceHandleRights:      "ErrUnableToReduceHandleRights",
	ErrUnspecifiedHandleRights:         "ErrUnspecifiedHandleRights",
	ErrMissingMarshalerContext:         "ErrMissingMarshalerContext",
	ErrResponseWithoutRequest:          "ErrResponseWithoutRequest",
	ErrDuplicateTxidReceived:           "ErrDuplicateTxidReceived",
	ErrDuplicateTxidWaiting:            "ErrDuplicateTxidWaiting",
	ErrIncorrectHandleType:             "ErrIncorrectHandleType",
	ErrUnspecifiedHandleType:           "ErrUnspecifiedHandleType",
	ErrValueTypeHandles:                "ErrValueTypeHandles",
	ErrExceededMaxOutOfLineDepth:       "ErrExceededMaxOutOfLineDepth",
	ErrInvalidInlineBitValueInEnvelope: "ErrInvalidInlineBitValueInEnvelope",
	ErrUnsupportedWireFormatVersion:    "ErrUnsupportedWireFormatVersion",
}

func (c ErrorCode) String() string {
	if len(errorCodeNames) < int(c) {
		return strconv.Itoa(int(c))
	}
	return errorCodeNames[int(c)]
}

// Error implements error for ErrorCode
func (e ErrorCode) Error() string {
	switch e {
	case ErrUnknownOrdinal:
		return "unknown ordinal"
	case ErrInvalidInlineType:
		return "invalid inline type"
	case ErrInvalidPointerType:
		return "invalid pointer type"
	case ErrVectorTooLong:
		return "vector exceeds maximum size"
	case ErrStringTooLong:
		return "string exceeds maximum size"
	case ErrUnexpectedOrdinal:
		return "unexpected ordinal"
	case ErrUnexpectedNullRef:
		return "unexpected null reference"
	case ErrInvalidBoolValue:
		return "unexpected boolean value"
	case ErrNotEnoughHandles:
		return "not enough handles"
	case ErrTooManyHandles:
		return "too many handles"
	case ErrBadHandleEncoding:
		return "bad encoding for handle"
	case ErrNonZeroPadding:
		return "invalid non-zero padding"
	case ErrBadRefEncoding:
		return "bad encoding for ref"
	case ErrBadInlineIndicatorEncoding:
		return "bad encoding for inline indicator"
	case ErrStructIsNotPayload:
		return "golang struct type must implement Payload"
	case ErrInvalidUnionTag:
		return "union tag out of bounds"
	case ErrInvalidXUnionTag:
		return "strict xunion has unknown tag"
	case ErrInvalidBitsValue:
		return "invalid bits value"
	case ErrInvalidEnumValue:
		return "invalid enum value"
	case ErrPayloadTooSmall:
		return "payload too small"
	case ErrInvalidEmptyStruct:
		return "invalid empty struct"
	case ErrInvalidNumBytesInEnvelope:
		return "unexpected num bytes in envelope"
	case ErrInvalidNumHandlesInEnvelope:
		return "unexpected num handles in envelope"
	case ErrStringNotUTF8:
		return "string is not valid UTF8"
	case ErrUnknownMagic:
		return "header magic number is not supported"
	case ErrMissingRequiredHandleRights:
		return "missing required handle rights"
	case ErrUnableToReduceHandleRights:
		return "unable to reduce handle rights"
	case ErrUnspecifiedHandleRights:
		return "handle rights are unspecified"
	case ErrMissingMarshalerContext:
		return "missing marshaler context"
	case ErrResponseWithoutRequest:
		return "received response without request (unexpected transaction id in mesage)"
	case ErrDuplicateTxidReceived:
		return "received multiple messages with the same transaction id"
	case ErrDuplicateTxidWaiting:
		return "multiple channel calls waiting on same transaction id"
	case ErrIncorrectHandleType:
		return "handle type is incorrect"
	case ErrUnspecifiedHandleType:
		return "handle type is unspecified"
	case ErrValueTypeHandles:
		return "cannot encode or decode value type with handles in unknown data"
	case ErrExceededMaxOutOfLineDepth:
		return "exceeded maxOutOfLineDepth"
	case ErrInvalidInlineBitValueInEnvelope:
		return "invalid inline bit value in envelope"
	case ErrUnsupportedWireFormatVersion:
		return "wire format version is not supported"
	default:
		return e.String()
	}
}

// Code implements the ValidationError interface.
func (e ErrorCode) Code() ErrorCode {
	return e
}

// stringer is an interface for types for which a string representation
// may be derived.
type stringer interface {
	String() string
}

// toString generates the string representation for a limited set of types.
func toString(value interface{}) string {
	if e, ok := value.(error); ok {
		return e.Error()
	}
	if s, ok := value.(stringer); ok {
		return s.String()
	}
	if numbers, ok := value.([]uint64); ok {
		s := "["
		for _, num := range numbers {
			s += strconv.FormatUint(num, 10)
			s += " "
		}
		s += "]"
		return s
	}
	t := reflect.TypeOf(value)
	switch t.Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return strconv.FormatInt(reflect.ValueOf(value).Int(), 10)
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		return strconv.FormatUint(reflect.ValueOf(value).Uint(), 10)
	case reflect.String:
		return value.(string)
	default:
		return "##BADVALUE##"
	}
}

// valueError represents an error that refers to a single value.
type valueError struct {
	ErrorCode
	value interface{}
}

func newValueError(code ErrorCode, value interface{}) valueError {
	return valueError{
		ErrorCode: code,
		value:     value,
	}
}

func (e valueError) Error() string {
	return e.ErrorCode.Error() + ": " + toString(e.value)
}

func (e valueError) Unwrap() error {
	return e.ErrorCode
}

// expectError represents an error that refers to the expectation of a
// certain value, and displays a comparison between the actual value and
// the expected value.
type expectError struct {
	ErrorCode
	expect interface{}
	actual interface{}
}

func newExpectError(code ErrorCode, expect, actual interface{}) expectError {
	return expectError{
		ErrorCode: code,
		expect:    expect,
		actual:    actual,
	}
}

func (e expectError) Error() string {
	return e.ErrorCode.Error() + ": expected " + toString(e.expect) + ", got " + toString(e.actual)
}

func (e expectError) Unwrap() error {
	return e.ErrorCode
}