// Copyright 2024 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package types

import (
	"github.com/dolthub/go-mysql-server/sql"
	"gopkg.in/src-d/go-errors.v1"

	"github.com/dolthub/doltgresql/utils"

	"github.com/dolthub/doltgresql/core/id"
)

// ErrWrongLengthBit is returned when a value with the incorrect length is inserted into a Bit column.
var ErrWrongLengthBit = errors.NewKind(`bit string length %d does not match type bit(%d)`)

// Bit is a fixed-length bit string.
var Bit = &DoltgresType{
	ID:                  toInternal("bit"),
	TypLength:           int16(-1),
	PassedByVal:         false,
	TypType:             TypeType_Base,
	TypCategory:         TypeCategory_BitStringTypes,
	IsPreferred:         false,
	IsDefined:           true,
	Delimiter:           ",",
	RelID:               id.Null,
	SubscriptFunc:       toFuncID("-"),
	Elem:                internalNullType,
	Array:               internalNullType,
	InputFunc:           toFuncID("bit_in", toInternal("cstring"), toInternal("oid"), toInternal("int4")),
	OutputFunc:          toFuncID("bit_out", toInternal("bit")),
	ReceiveFunc:         toFuncID("bit_recv", toInternal("internal"), toInternal("oid"), toInternal("int4")),
	SendFunc:            toFuncID("bit_send", toInternal("bit")),
	ModInFunc:           toFuncID("bittypmodin", toInternal("_cstring")),
	ModOutFunc:          toFuncID("bittypmodout", toInternal("int4")),
	AnalyzeFunc:         toFuncID("-"),
	Align:               TypeAlignment_Int,
	Storage:             TypeStorage_Extended,
	NotNull:             false,
	BaseTypeType:        internalNullType,
	TypMod:              -1,
	NDims:               0,
	TypCollation:        id.NewCollation("pg_catalog", "default"),
	DefaulBin:           "",
	Default:             "",
	Acl:                 nil,
	Checks:              nil,
	attTypMod:           -1,
	CompareFunc:         toFuncID("bitcmp", toInternal("bit"), toInternal("bit")),
	SerializationFunc:   serializeTypeBit,
	DeserializationFunc: deserializeTypeBit,
}

// NewBitType returns a Bit type with type modifier set
// representing the number of bits in the string.
func NewBitType(width int32) (*DoltgresType, error) {
	if width < 1 {
		return nil, ErrLengthMustBeAtLeast1.New("bit")
	} else if width > StringMaxLength {
		return nil, ErrLengthCannotExceed.New("bit")
	}
	newType := *Bit.WithAttTypMod(width)
	return &newType, nil
}

// serializeTypeBit handles serialization from the standard representation to our serialized representation that is
// written in Dolt.
func serializeTypeBit(ctx *sql.Context, t *DoltgresType, val any) ([]byte, error) {
	str := val.(string)
	wr := utils.NewWriter(uint64(4 + len(str)))
	wr.String(str)
	return wr.Data(), nil
}

// deserializeTypeBit handles deserialization from the Dolt serialized format to our standard representation used by
// expressions and nodes.
func deserializeTypeBit(ctx *sql.Context, t *DoltgresType, data []byte) (any, error) {
	if len(data) == 0 {
		return nil, nil
	}
	reader := utils.NewReader(data)
	return reader.String(), nil
}