// Copyright 2016 The Xorm Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package xorm

import (
	"bufio"
	"context"
	"database/sql"
	"fmt"
	"io"
	"os"
	"strings"

	"xorm.io/xorm/dialects"
	"xorm.io/xorm/internal/utils"
)

// Ping test if database is ok
func (session *Session) Ping() error {
	if session.isAutoClose {
		defer session.Close()
	}

	session.engine.logger.Infof("PING DATABASE %v", session.engine.DriverName())
	return session.DB().PingContext(session.ctx)
}

// CreateTable create a table according a bean
func (session *Session) CreateTable(bean interface{}) error {
	if session.isAutoClose {
		defer session.Close()
	}

	return session.createTable(bean)
}

func (session *Session) createTable(bean interface{}) error {
	if err := session.statement.SetRefBean(bean); err != nil {
		return err
	}

	session.statement.RefTable.StoreEngine = session.statement.StoreEngine
	session.statement.RefTable.Charset = session.statement.Charset
	tableName := session.statement.TableName()
	refTable := session.statement.RefTable
	if refTable.AutoIncrement != "" && session.engine.dialect.Features().AutoincrMode == dialects.SequenceAutoincrMode {
		sqlStr, err := session.engine.dialect.CreateSequenceSQL(context.Background(), session.engine.db, utils.SeqName(tableName))
		if err != nil {
			return err
		}
		if _, err := session.exec(sqlStr); err != nil {
			return err
		}
	}

	sqlStr, _, err := session.engine.dialect.CreateTableSQL(context.Background(), session.engine.db, refTable, tableName)
	if err != nil {
		return err
	}
	if _, err := session.exec(sqlStr); err != nil {
		return err
	}

	return nil
}

// CreateIndexes create indexes
func (session *Session) CreateIndexes(bean interface{}) error {
	if session.isAutoClose {
		defer session.Close()
	}

	return session.createIndexes(bean)
}

func (session *Session) createIndexes(bean interface{}) error {
	if err := session.statement.SetRefBean(bean); err != nil {
		return err
	}

	sqls := session.statement.GenIndexSQL()
	for _, sqlStr := range sqls {
		_, err := session.exec(sqlStr)
		if err != nil {
			return err
		}
	}
	return nil
}

// CreateUniques create uniques
func (session *Session) CreateUniques(bean interface{}) error {
	if session.isAutoClose {
		defer session.Close()
	}
	return session.createUniques(bean)
}

func (session *Session) createUniques(bean interface{}) error {
	if err := session.statement.SetRefBean(bean); err != nil {
		return err
	}

	sqls := session.statement.GenUniqueSQL()
	for _, sqlStr := range sqls {
		_, err := session.exec(sqlStr)
		if err != nil {
			return err
		}
	}
	return nil
}

// DropIndexes drop indexes
func (session *Session) DropIndexes(bean interface{}) error {
	if session.isAutoClose {
		defer session.Close()
	}

	return session.dropIndexes(bean)
}

func (session *Session) dropIndexes(bean interface{}) error {
	if err := session.statement.SetRefBean(bean); err != nil {
		return err
	}

	sqls := session.statement.GenDelIndexSQL()
	for _, sqlStr := range sqls {
		_, err := session.exec(sqlStr)
		if err != nil {
			return err
		}
	}
	return nil
}

// DropTable drop table will drop table if exist, if drop failed, it will return error
func (session *Session) DropTable(beanOrTableName interface{}) error {
	if session.isAutoClose {
		defer session.Close()
	}

	return session.dropTable(beanOrTableName)
}

func (session *Session) dropTable(beanOrTableName interface{}) error {
	tableName := session.engine.TableName(beanOrTableName)
	sqlStr, checkIfExist := session.engine.dialect.DropTableSQL(session.engine.TableName(tableName, true))
	if !checkIfExist {
		exist, err := session.engine.dialect.IsTableExist(session.getQueryer(), session.ctx, tableName)
		if err != nil {
			return err
		}
		checkIfExist = exist
	}

	if !checkIfExist {
		return nil
	}
	if _, err := session.exec(sqlStr); err != nil {
		return err
	}

	if session.engine.dialect.Features().AutoincrMode == dialects.IncrAutoincrMode {
		return nil
	}

	seqName := utils.SeqName(tableName)
	exist, err := session.engine.dialect.IsSequenceExist(session.ctx, session.getQueryer(), seqName)
	if err != nil {
		return err
	}
	if !exist {
		return nil
	}

	sqlStr, err = session.engine.dialect.DropSequenceSQL(seqName)
	if err != nil {
		return err
	}
	_, err = session.exec(sqlStr)
	return err
}

// IsTableExist if a table is exist
func (session *Session) IsTableExist(beanOrTableName interface{}) (bool, error) {
	if session.isAutoClose {
		defer session.Close()
	}

	tableName := session.engine.TableName(beanOrTableName)

	return session.isTableExist(tableName)
}

func (session *Session) isTableExist(tableName string) (bool, error) {
	return session.engine.dialect.IsTableExist(session.getQueryer(), session.ctx, tableName)
}

// IsTableEmpty if table have any records
func (session *Session) IsTableEmpty(bean interface{}) (bool, error) {
	if session.isAutoClose {
		defer session.Close()
	}
	return session.isTableEmpty(session.engine.TableName(bean))
}

func (session *Session) isTableEmpty(tableName string) (bool, error) {
	var total int64
	sqlStr := fmt.Sprintf("select count(*) from %s", session.engine.Quote(session.engine.TableName(tableName, true)))
	err := session.queryRow(sqlStr).Scan(&total)
	if err != nil {
		if err == sql.ErrNoRows {
			err = nil
		}
		return true, err
	}

	return total == 0, nil
}

func (session *Session) addColumn(colName string) error {
	col := session.statement.RefTable.GetColumn(colName)
	sql := session.engine.dialect.AddColumnSQL(session.statement.TableName(), col)
	_, err := session.exec(sql)
	return err
}

func (session *Session) addIndex(tableName, idxName string) error {
	index := session.statement.RefTable.Indexes[idxName]
	sqlStr := session.engine.dialect.CreateIndexSQL(tableName, index)
	_, err := session.exec(sqlStr)
	return err
}

func (session *Session) addUnique(tableName, uqeName string) error {
	index := session.statement.RefTable.Indexes[uqeName]
	sqlStr := session.engine.dialect.CreateIndexSQL(tableName, index)
	_, err := session.exec(sqlStr)
	return err
}

// ImportFile SQL DDL file
func (session *Session) ImportFile(ddlPath string) ([]sql.Result, error) {
	file, err := os.Open(ddlPath)
	if err != nil {
		return nil, err
	}
	defer file.Close()
	return session.Import(file)
}

// Import SQL DDL from io.Reader
func (session *Session) Import(r io.Reader) ([]sql.Result, error) {
	var (
		results       []sql.Result
		lastError     error
		inSingleQuote bool
		startComment  bool
	)

	scanner := bufio.NewScanner(r)
	semiColSpliter := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
		if atEOF && len(data) == 0 {
			return 0, nil, nil
		}
		oriInSingleQuote := inSingleQuote
		for i, b := range data {
			if startComment {
				if b == '\n' {
					startComment = false
				}
			} else {
				if !inSingleQuote && i > 0 && data[i-1] == '-' && data[i] == '-' {
					startComment = true
					continue
				}

				if b == '\'' {
					inSingleQuote = !inSingleQuote
				}
				if !inSingleQuote && b == ';' {
					return i + 1, data[0:i], nil
				}
			}
		}
		// If we're at EOF, we have a final, non-terminated line. Return it.
		if atEOF {
			return len(data), data, nil
		}
		inSingleQuote = oriInSingleQuote
		// Request more data.
		return 0, nil, nil
	}

	scanner.Split(semiColSpliter)

	for scanner.Scan() {
		query := strings.Trim(scanner.Text(), " \t\n\r")
		if len(query) > 0 {
			result, err := session.Exec(query)
			if err != nil {
				return nil, err
			}
			results = append(results, result)
		}
	}

	return results, lastError
}