// 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"
	"time"

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

	"github.com/dolthub/doltgresql/postgres/parser/sem/tree"
	"github.com/dolthub/doltgresql/postgres/parser/timeofday"
	"github.com/dolthub/doltgresql/postgres/parser/timetz"
	"github.com/dolthub/doltgresql/server/functions/framework"
	pgtypes "github.com/dolthub/doltgresql/server/types"
	"github.com/dolthub/doltgresql/utils"
)

// initTimeTZ registers the functions to the catalog.
func initTimeTZ() {
	framework.RegisterFunction(timetz_in)
	framework.RegisterFunction(timetz_out)
	framework.RegisterFunction(timetz_recv)
	framework.RegisterFunction(timetz_send)
	framework.RegisterFunction(timetztypmodin)
	framework.RegisterFunction(timetztypmodout)
	framework.RegisterFunction(timetz_cmp)
}

// timetz_in represents the PostgreSQL function of timetz type IO input.
var timetz_in = framework.Function3{
	Name:       "timetz_in",
	Return:     pgtypes.TimeTZ,
	Parameters: [3]*pgtypes.DoltgresType{pgtypes.Cstring, pgtypes.Oid, pgtypes.Int32},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [4]*pgtypes.DoltgresType, val1, val2, val3 any) (any, error) {
		input := strings.TrimSpace(val1.(string))
		typmod := val3.(int32)
		if typmod == -1 {
			typmod = 6
		}
		precision := tree.TimeFamilyPrecisionToRoundDuration(typmod)
		if strings.EqualFold(input, "now") {
			t := ctx.QueryTime()
			t = t.Round(precision)
			return timetz.MakeTimeTZFromLocation(timeofday.New(t.Hour(), t.Minute(), t.Second(), t.Nanosecond()/1000), t.Location()), nil
		}
		loc, err := GetServerLocation(ctx)
		if err != nil {
			return nil, err
		}
		t, _, err := timetz.ParseTimeTZ(time.Now().In(loc), input, precision)
		if err != nil {
			return nil, err
		}
		return t, nil
	},
}

// timetz_out represents the PostgreSQL function of timetz type IO output.
var timetz_out = framework.Function1{
	Name:       "timetz_out",
	Return:     pgtypes.Cstring,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.TimeTZ},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		return val.(timetz.TimeTZ).String(), nil
	},
}

// timetz_recv represents the PostgreSQL function of timetz type IO receive.
var timetz_recv = framework.Function3{
	Name:       "timetz_recv",
	Return:     pgtypes.TimeTZ,
	Parameters: [3]*pgtypes.DoltgresType{pgtypes.Internal, pgtypes.Oid, pgtypes.Int32},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [4]*pgtypes.DoltgresType, val1, val2, val3 any) (any, error) {
		// TODO: decode typmod to precision
		data := val1.([]byte)
		if data == nil {
			return nil, nil
		}
		reader := utils.NewWireReader(data)
		tod := reader.ReadInt64()
		offset := reader.ReadInt32()
		return timetz.MakeTimeTZ(timeofday.TimeOfDay(tod), offset), nil
	},
}

// timetz_send represents the PostgreSQL function of timetz type IO send.
var timetz_send = framework.Function1{
	Name:       "timetz_send",
	Return:     pgtypes.Bytea,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.TimeTZ},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		tim := val.(timetz.TimeTZ)
		writer := utils.NewWireWriter()
		writer.WriteInt64(int64(tim.TimeOfDay))
		writer.WriteInt32(tim.OffsetSecs)
		return writer.BufferData(), nil
	},
}

// timetztypmodin represents the PostgreSQL function of timetz type IO typmod input.
var timetztypmodin = framework.Function1{
	Name:       "timetztypmodin",
	Return:     pgtypes.Int32,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.CstringArray},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		// TODO: typmod=(precision<<16)∣scale
		return nil, nil
	},
}

// timetztypmodout represents the PostgreSQL function of timetz type IO typmod output.
var timetztypmodout = framework.Function1{
	Name:       "timetztypmodout",
	Return:     pgtypes.Cstring,
	Parameters: [1]*pgtypes.DoltgresType{pgtypes.Int32},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
		// TODO
		// Precision = typmod & 0xFFFF
		// Scale = (typmod >> 16) & 0xFFFF
		return nil, nil
	},
}

// timetz_cmp represents the PostgreSQL function of timetz type compare.
var timetz_cmp = framework.Function2{
	Name:       "timetz_cmp",
	Return:     pgtypes.Int32,
	Parameters: [2]*pgtypes.DoltgresType{pgtypes.TimeTZ, pgtypes.TimeTZ},
	Strict:     true,
	Callable: func(ctx *sql.Context, _ [3]*pgtypes.DoltgresType, val1, val2 any) (any, error) {
		ab := val1.(timetz.TimeTZ)
		bb := val2.(timetz.TimeTZ)
		return int32(ab.Compare(bb)), nil
	},
}

// GetServerLocation returns timezone value set for the server.
func GetServerLocation(ctx *sql.Context) (*time.Location, error) {
	if ctx == nil {
		return time.Local, nil
	}
	val, err := ctx.GetSessionVariable(ctx, "timezone")
	if err != nil {
		return nil, err
	}

	loc, _, _, err := convertTzToOffsetSecs(time.Now(), val.(string))
	return loc, err
}