// 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 functions

import (
	"strings"

	"github.com/cockroachdb/errors"
	"github.com/dolthub/go-mysql-server/sql"

	"github.com/dolthub/doltgresql/server/functions/framework"
	pgtypes "github.com/dolthub/doltgresql/server/types"
	"github.com/dolthub/doltgresql/utils"
)

// initChar registers the functions to the catalog.
func initChar() {
	framework.RegisterFunction(charin)
	framework.RegisterFunction(charout)
	framework.RegisterFunction(charrecv)
	framework.RegisterFunction(charsend)
	framework.RegisterFunction(btcharcmp)
}

// charin represents the PostgreSQL function of "char" type IO input.
var charin = framework.Function1{
	Name:       "charin",
	Return:     pgtypes.InternalChar,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.Cstring},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		input := val.(string)
		c := []byte(input)
		if uint32(len(c)) > pgtypes.InternalCharLength {
			return input[:pgtypes.InternalCharLength], nil
		}
		return input, nil
	},
}

// charout represents the PostgreSQL function of "char" type IO output.
var charout = framework.Function1{
	Name:       "charout",
	Return:     pgtypes.Cstring,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.InternalChar},
	Strict:     true,
	Callable: func(ctx *sql.Context, t [2]*pgtypes.DoltgresType, val any) (any, error) {
		str := val.(string)
		if uint32(len(str)) > pgtypes.InternalCharLength {
			return str[:pgtypes.InternalCharLength], nil
		}
		return str, nil
	},
}

// charrecv represents the PostgreSQL function of "char" type IO receive.
var charrecv = framework.Function1{
	Name:       "charrecv",
	Return:     pgtypes.InternalChar,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.Internal},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		data := val.([]byte)
		if data == nil {
			return nil, nil
		}
		if len(data) == 0 {
			return "", nil
		}
		return string(data[0]), nil
	},
}

// charsend represents the PostgreSQL function of "char" type IO send.
var charsend = framework.Function1{
	Name:       "charsend",
	Return:     pgtypes.Bytea,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.InternalChar},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		if wrapper, ok := val.(sql.AnyWrapper); ok {
			var err error
			val, err = wrapper.UnwrapAny(ctx)
			if err != nil {
				return nil, err
			}
			if val == nil {
				return nil, nil
			}
		}
		str := val.(string)
		writer := utils.NewWireWriter()
		if len(str) == 1 {
			writer.WriteUint8(str[0])
		} else if len(str) == 0 {
			writer.WriteUint8(0)
		} else {
			return nil, errors.New(`"char" found multiple characters during binary wire formatting`)
		}
		return writer.BufferData(), nil
	},
}

// btcharcmp represents the PostgreSQL function of "char" type compare.
var btcharcmp = framework.Function2{
	Name:       "btcharcmp",
	Return:     pgtypes.Int32,
	Parameters: [2]*pgtypes.DoltgresType{pgtypes.InternalChar, pgtypes.InternalChar},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [3]*pgtypes.DoltgresType, val1, val2 any) (any, error) {
		ab := strings.TrimRight(val1.(string), " ")
		bb := strings.TrimRight(val2.(string), " ")
		if ab == bb {
			return int32(0), nil
		} else if ab < bb {
			return int32(-1), nil
		} else {
			return int32(1), nil
		}
	},
}