// 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 pgcatalog

import (
	"io"

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

	"github.com/dolthub/doltgresql/server/tables"
	pgtypes "github.com/dolthub/doltgresql/server/types"
)

// PgStatDatabaseName is a constant to the pg_stat_database name.
const PgStatDatabaseName = "pg_stat_database"

// InitPgStatDatabase handles registration of the pg_stat_database handler.
func InitPgStatDatabase() {
	tables.AddHandler(PgCatalogName, PgStatDatabaseName, PgStatDatabaseHandler{})
}

// PgStatDatabaseHandler is the handler for the pg_stat_database table.
type PgStatDatabaseHandler struct{}

var _ tables.Handler = PgStatDatabaseHandler{}

// Name implements the interface tables.Handler.
func (p PgStatDatabaseHandler) Name() string {
	return PgStatDatabaseName
}

// RowIter implements the interface tables.Handler.
func (p PgStatDatabaseHandler) RowIter(ctx *sql.Context, partition sql.Partition) (sql.RowIter, error) {
	// TODO: Implement pg_stat_database row iter
	return emptyRowIter()
}

// PkSchema implements the interface tables.Handler.
func (p PgStatDatabaseHandler) PkSchema() sql.PrimaryKeySchema {
	return sql.PrimaryKeySchema{
		Schema:     pgStatDatabaseSchema,
		PkOrdinals: nil,
	}
}

// pgStatDatabaseSchema is the schema for pg_stat_database.
var pgStatDatabaseSchema = sql.Schema{
	{Name: "datid", Type: pgtypes.Oid, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "datname", Type: pgtypes.Name, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "numbackends", Type: pgtypes.Int32, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "xact_commit", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "xact_rollback", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "blks_read", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "blks_hit", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "tup_returned", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "tup_fetched", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "tup_inserted", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "tup_updated", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "tup_deleted", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "conflicts", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "temp_files", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "temp_bytes", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "deadlocks", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "checksum_failures", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "checksum_last_failure", Type: pgtypes.TimestampTZ, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "blk_read_time", Type: pgtypes.Float64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "blk_write_time", Type: pgtypes.Float64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "session_time", Type: pgtypes.Float64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "active_time", Type: pgtypes.Float64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "idle_in_transaction_time", Type: pgtypes.Float64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "sessions", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "sessions_abandoned", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "sessions_fatal", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "sessions_killed", Type: pgtypes.Int64, Default: nil, Nullable: true, Source: PgStatDatabaseName},
	{Name: "stats_reset", Type: pgtypes.TimestampTZ, Default: nil, Nullable: true, Source: PgStatDatabaseName},
}

// pgStatDatabaseRowIter is the sql.RowIter for the pg_stat_database table.
type pgStatDatabaseRowIter struct {
}

var _ sql.RowIter = (*pgStatDatabaseRowIter)(nil)

// Next implements the interface sql.RowIter.
func (iter *pgStatDatabaseRowIter) Next(ctx *sql.Context) (sql.Row, error) {
	return nil, io.EOF
}

// Close implements the interface sql.RowIter.
func (iter *pgStatDatabaseRowIter) Close(ctx *sql.Context) error {
	return nil
}