// Copyright 2015 PingCAP, 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,
// See the License for the specific language governing permissions and
// limitations under the License.

package server

import (
	"fmt"

	"github.com/pingcap/tidb/util/types"
)

// IDriver opens IContext.
type IDriver interface {
	// OpenCtx opens an IContext with connection id, client capability, collation and dbname.
	OpenCtx(connID uint64, capability uint32, collation uint8, dbname string) (QueryCtx, error)
}

// QueryCtx is the interface to execute command.
type QueryCtx interface {
	// Status returns server status code.
	Status() uint16

	// LastInsertID returns last inserted ID.
	LastInsertID() uint64

	// AffectedRows returns affected rows of last executed command.
	AffectedRows() uint64

	// Value returns the value associated with this context for key.
	Value(key fmt.Stringer) interface{}

	// SetValue saves a value associated with this context for key.
	SetValue(key fmt.Stringer, value interface{})

	// CommitTxn commits the transaction operations.
	CommitTxn() error

	// RollbackTxn undoes the transaction operations.
	RollbackTxn() error

	// WarningCount returns warning count of last executed command.
	WarningCount() uint16

	// CurrentDB returns current DB.
	CurrentDB() string

	// Execute executes a SQL statement.
	Execute(sql string) ([]ResultSet, error)

	// SetClientCapability sets client capability flags
	SetClientCapability(uint32)

	// Prepare prepares a statement.
	Prepare(sql string) (statement PreparedStatement, columns, params []*ColumnInfo, err error)

	// GetStatement gets PreparedStatement by statement ID.
	GetStatement(stmtID int) PreparedStatement

	// FieldList returns columns of a table.
	FieldList(tableName string) (columns []*ColumnInfo, err error)

	// Close closes the IContext.
	Close() error

	// Auth verifies user's authentication.
	Auth(user string, auth []byte, salt []byte) bool
}

// PreparedStatement is the interface to use a prepared statement.
type PreparedStatement interface {
	// ID returns statement ID
	ID() int

	// Execute executes the statement.
	Execute(args ...interface{}) (ResultSet, error)

	// AppendParam appends parameter to the statement.
	AppendParam(paramID int, data []byte) error

	// NumParams returns number of parameters.
	NumParams() int

	// BoundParams returns bound parameters.
	BoundParams() [][]byte

	// SetParamsType sets type for parameters.
	SetParamsType([]byte)

	// GetParamsType returns the type for parameters.
	GetParamsType() []byte

	// Reset removes all bound parameters.
	Reset()

	// Close closes the statement.
	Close() error
}

// ResultSet is the result set of an query.
type ResultSet interface {
	Columns() ([]*ColumnInfo, error)
	Next() ([]types.Datum, error)
	Close() error
}