// Copyright GoFrame Author(https://goframe.org). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.
//
// Note:
// 1. It needs manually import: _ "github.com/denisenkom/go-mssqldb"
// 2. It does not support Save/Replace features.
// 3. It does not support LastInsertId.

// Package mssql implements gdb.Driver, which supports operations for MSSql.
package mssql

import (
	_ "github.com/denisenkom/go-mssqldb"

	"context"
	"database/sql"
	"fmt"
	"strconv"
	"strings"

	"github.com/gogf/gf/v2/container/gmap"
	"github.com/gogf/gf/v2/database/gdb"
	"github.com/gogf/gf/v2/errors/gcode"
	"github.com/gogf/gf/v2/errors/gerror"
	"github.com/gogf/gf/v2/text/gregex"
	"github.com/gogf/gf/v2/text/gstr"
)

// DriverMssql is the driver for SQL server database.
type DriverMssql struct {
	*gdb.Core
}

var (
	// tableFieldsMap caches the table information retrieved from database.
	tableFieldsMap = gmap.New(true)
)

func init() {
	if err := gdb.Register(`mssql`, New()); err != nil {
		panic(err)
	}
}

// New create and returns a driver that implements gdb.Driver, which supports operations for Mssql.
func New() gdb.Driver {
	return &DriverMssql{}
}

// New creates and returns a database object for SQL server.
// It implements the interface of gdb.Driver for extra database driver installation.
func (d *DriverMssql) New(core *gdb.Core, node *gdb.ConfigNode) (gdb.DB, error) {
	return &DriverMssql{
		Core: core,
	}, nil
}

// Open creates and returns an underlying sql.DB object for mssql.
func (d *DriverMssql) Open(config *gdb.ConfigNode) (db *sql.DB, err error) {
	var (
		source               string
		underlyingDriverName = "sqlserver"
	)
	if config.Link != "" {
		source = config.Link
	} else {
		source = fmt.Sprintf(
			"user id=%s;password=%s;server=%s;port=%s;database=%s;encrypt=disable",
			config.User, config.Pass, config.Host, config.Port, config.Name,
		)
	}

	if db, err = sql.Open(underlyingDriverName, source); err != nil {
		err = gerror.WrapCodef(
			gcode.CodeDbOperationError, err,
			`sql.Open failed for driver "%s" by source "%s"`, underlyingDriverName, source,
		)
		return nil, err
	}
	return
}

// FilteredLink retrieves and returns filtered `linkInfo` that can be using for
// logging or tracing purpose.
func (d *DriverMssql) FilteredLink() string {
	linkInfo := d.GetConfig().Link
	if linkInfo == "" {
		return ""
	}
	s, _ := gregex.ReplaceString(
		`(.+);\s*password=(.+);\s*server=(.+)`,
		`$1;password=xxx;server=$3`,
		d.GetConfig().Link,
	)
	return s
}

// GetChars returns the security char for this type of database.
func (d *DriverMssql) GetChars() (charLeft string, charRight string) {
	return "\"", "\""
}

// DoFilter deals with the sql string before commits it to underlying sql driver.
func (d *DriverMssql) DoFilter(ctx context.Context, link gdb.Link, sql string, args []interface{}) (newSql string, newArgs []interface{}, err error) {
	defer func() {
		newSql, newArgs, err = d.Core.DoFilter(ctx, link, newSql, newArgs)
	}()
	var index int
	// Convert placeholder char '?' to string "@px".
	str, _ := gregex.ReplaceStringFunc("\\?", sql, func(s string) string {
		index++
		return fmt.Sprintf("@p%d", index)
	})
	str, _ = gregex.ReplaceString("\"", "", str)
	return d.parseSql(str), args, nil
}

// parseSql does some replacement of the sql before commits it to underlying driver,
// for support of microsoft sql server.
func (d *DriverMssql) parseSql(sql string) string {
	// SELECT * FROM USER WHERE ID=1 LIMIT 1
	if m, _ := gregex.MatchString(`^SELECT(.+)LIMIT 1$`, sql); len(m) > 1 {
		return fmt.Sprintf(`SELECT TOP 1 %s`, m[1])
	}
	// SELECT * FROM USER WHERE AGE>18 ORDER BY ID DESC LIMIT 100, 200
	patten := `^\s*(?i)(SELECT)|(LIMIT\s*(\d+)\s*,\s*(\d+))`
	if gregex.IsMatchString(patten, sql) == false {
		return sql
	}
	res, err := gregex.MatchAllString(patten, sql)
	if err != nil {
		return ""
	}
	index := 0
	keyword := strings.TrimSpace(res[index][0])
	keyword = strings.ToUpper(keyword)
	index++
	switch keyword {
	case "SELECT":
		// LIMIT statement checks.
		if len(res) < 2 ||
			(strings.HasPrefix(res[index][0], "LIMIT") == false &&
				strings.HasPrefix(res[index][0], "limit") == false) {
			break
		}
		if gregex.IsMatchString("((?i)SELECT)(.+)((?i)LIMIT)", sql) == false {
			break
		}
		// ORDER BY statement checks.
		selectStr := ""
		orderStr := ""
		haveOrder := gregex.IsMatchString("((?i)SELECT)(.+)((?i)ORDER BY)", sql)
		if haveOrder {
			queryExpr, _ := gregex.MatchString("((?i)SELECT)(.+)((?i)ORDER BY)", sql)
			if len(queryExpr) != 4 ||
				strings.EqualFold(queryExpr[1], "SELECT") == false ||
				strings.EqualFold(queryExpr[3], "ORDER BY") == false {
				break
			}
			selectStr = queryExpr[2]
			orderExpr, _ := gregex.MatchString("((?i)ORDER BY)(.+)((?i)LIMIT)", sql)
			if len(orderExpr) != 4 ||
				strings.EqualFold(orderExpr[1], "ORDER BY") == false ||
				strings.EqualFold(orderExpr[3], "LIMIT") == false {
				break
			}
			orderStr = orderExpr[2]
		} else {
			queryExpr, _ := gregex.MatchString("((?i)SELECT)(.+)((?i)LIMIT)", sql)
			if len(queryExpr) != 4 ||
				strings.EqualFold(queryExpr[1], "SELECT") == false ||
				strings.EqualFold(queryExpr[3], "LIMIT") == false {
				break
			}
			selectStr = queryExpr[2]
		}
		first, limit := 0, 0
		for i := 1; i < len(res[index]); i++ {
			if len(strings.TrimSpace(res[index][i])) == 0 {
				continue
			}

			if strings.HasPrefix(res[index][i], "LIMIT") ||
				strings.HasPrefix(res[index][i], "limit") {
				first, _ = strconv.Atoi(res[index][i+1])
				limit, _ = strconv.Atoi(res[index][i+2])
				break
			}
		}
		if haveOrder {
			sql = fmt.Sprintf(
				"SELECT * FROM "+
					"(SELECT ROW_NUMBER() OVER (ORDER BY %s) as ROWNUMBER_, %s ) as TMP_ "+
					"WHERE TMP_.ROWNUMBER_ > %d AND TMP_.ROWNUMBER_ <= %d",
				orderStr, selectStr, first, first+limit,
			)
		} else {
			if first == 0 {
				first = limit
			}
			sql = fmt.Sprintf(
				"SELECT * FROM (SELECT TOP %d * FROM (SELECT TOP %d %s) as TMP1_ ) as TMP2_ ",
				limit, first+limit, selectStr,
			)
		}
	default:
	}
	return sql
}

// Tables retrieves and returns the tables of current schema.
// It's mainly used in cli tool chain for automatically generating the models.
func (d *DriverMssql) Tables(ctx context.Context, schema ...string) (tables []string, err error) {
	var result gdb.Result
	link, err := d.SlaveLink(schema...)
	if err != nil {
		return nil, err
	}

	result, err = d.DoGetAll(ctx, link, `SELECT NAME FROM SYSOBJECTS WHERE XTYPE='U' AND STATUS >= 0 ORDER BY NAME`)
	if err != nil {
		return
	}
	for _, m := range result {
		for _, v := range m {
			tables = append(tables, v.String())
		}
	}
	return
}

// TableFields retrieves and returns the fields information of specified table of current schema.
//
// Also see DriverMysql.TableFields.
func (d *DriverMssql) TableFields(ctx context.Context, table string, schema ...string) (fields map[string]*gdb.TableField, err error) {
	charL, charR := d.GetChars()
	table = gstr.Trim(table, charL+charR)
	if gstr.Contains(table, " ") {
		return nil, gerror.NewCode(gcode.CodeInvalidParameter, "function TableFields supports only single table operations")
	}
	useSchema := d.GetSchema()
	if len(schema) > 0 && schema[0] != "" {
		useSchema = schema[0]
	}
	v := tableFieldsMap.GetOrSetFuncLock(
		fmt.Sprintf(`mssql_table_fields_%s_%s@group:%s`, table, useSchema, d.GetGroup()),
		func() interface{} {
			var (
				result gdb.Result
				link   gdb.Link
			)
			if link, err = d.SlaveLink(useSchema); err != nil {
				return nil
			}
			structureSql := fmt.Sprintf(`
SELECT 
	a.name Field,
	CASE b.name 
		WHEN 'datetime' THEN 'datetime'
		WHEN 'numeric' THEN b.name + '(' + convert(varchar(20), a.xprec) + ',' + convert(varchar(20), a.xscale) + ')' 
		WHEN 'char' THEN b.name + '(' + convert(varchar(20), a.length)+ ')'
		WHEN 'varchar' THEN b.name + '(' + convert(varchar(20), a.length)+ ')'
		ELSE b.name + '(' + convert(varchar(20),a.length)+ ')' END AS Type,
	CASE WHEN a.isnullable=1 THEN 'YES' ELSE 'NO' end AS [Null],
	CASE WHEN exists (
		SELECT 1 FROM sysobjects WHERE xtype='PK' AND name IN (
			SELECT name FROM sysindexes WHERE indid IN (
				SELECT indid FROM sysindexkeys WHERE id = a.id AND colid=a.colid
			)
		)
	) THEN 'PRI' ELSE '' END AS [Key],
	CASE WHEN COLUMNPROPERTY(a.id,a.name,'IsIdentity')=1 THEN 'auto_increment' ELSE '' END Extra,
	isnull(e.text,'') AS [Default],
	isnull(g.[value],'') AS [Comment]
FROM syscolumns a
LEFT JOIN systypes b ON a.xtype=b.xtype AND a.xusertype=b.xusertype
INNER JOIN sysobjects d ON a.id=d.id AND d.xtype='U' AND d.name<>'dtproperties'
LEFT JOIN syscomments e ON a.cdefault=e.id
LEFT JOIN sys.extended_properties g ON a.id=g.major_id AND a.colid=g.minor_id
LEFT JOIN sys.extended_properties f ON d.id=f.major_id AND f.minor_id =0
WHERE d.name='%s'
ORDER BY a.id,a.colorder`,
				strings.ToUpper(table),
			)
			structureSql, _ = gregex.ReplaceString(`[\n\r\s]+`, " ", gstr.Trim(structureSql))
			result, err = d.DoGetAll(ctx, link, structureSql)
			if err != nil {
				return nil
			}
			fields = make(map[string]*gdb.TableField)
			for i, m := range result {
				fields[strings.ToLower(m["Field"].String())] = &gdb.TableField{
					Index:   i,
					Name:    strings.ToLower(m["Field"].String()),
					Type:    strings.ToLower(m["Type"].String()),
					Null:    m["Null"].Bool(),
					Key:     m["Key"].String(),
					Default: m["Default"].Val(),
					Extra:   m["Extra"].String(),
					Comment: m["Comment"].String(),
				}
			}
			return fields
		},
	)
	if v != nil {
		fields = v.(map[string]*gdb.TableField)
	}
	return
}

// DoInsert is not supported in mssql.
func (d *DriverMssql) DoInsert(ctx context.Context, link gdb.Link, table string, list gdb.List, option gdb.DoInsertOption) (result sql.Result, err error) {
	switch option.InsertOption {
	case gdb.InsertOptionSave:
		return nil, gerror.NewCode(gcode.CodeNotSupported, `Save operation is not supported by mssql driver`)

	case gdb.InsertOptionReplace:
		return nil, gerror.NewCode(gcode.CodeNotSupported, `Replace operation is not supported by mssql driver`)

	default:
		return d.Core.DoInsert(ctx, link, table, list, option)
	}
}