// Copyright 2017 gf Author(https://github.com/gogf/gf). 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.
// 说明：
//    1.需要导入oracle驱动： github.com/mattn/go-oci8
//    2.不支持save/replace方法，可以调用这2个方法估计会报错，还没测试过,(应该是可以通过oracle的merge来实现这2个功能的，还没仔细研究)
//    3.不支持LastInsertId方法

package gdb

import (
	"database/sql"
	"errors"
	"fmt"
	"reflect"
	"strconv"
	"strings"

	"github.com/gogf/gf/text/gregex"
)

// 数据库链接对象
type dbOracle struct {
	*dbBase
}

const (
	tableAlias1 = "GFORM1"
	tableAlias2 = "GFORM2"
)

// 创建SQL操作对象
func (db *dbOracle) Open(config *ConfigNode) (*sql.DB, error) {
	var source string
	if config.LinkInfo != "" {
		source = config.LinkInfo
	} else {
		source = fmt.Sprintf("%s/%s@%s", config.User, config.Pass, config.Name)
	}
	if db, err := sql.Open("oci8", source); err == nil {
		return db, nil
	} else {
		return nil, err
	}
}

// 获得关键字操作符
func (db *dbOracle) getChars() (charLeft string, charRight string) {
	return "\"", "\""
}

// 在执行sql之前对sql进行进一步处理
func (db *dbOracle) handleSqlBeforeExec(query string) string {
	index := 0
	str, _ := gregex.ReplaceStringFunc("\\?", query, func(s string) string {
		index++
		return fmt.Sprintf(":%d", index)
	})

	str, _ = gregex.ReplaceString("\"", "", str)

	return db.parseSql(str)
}

//由于ORACLE中对LIMIT和批量插入的语法与MYSQL不一致，所以这里需要对LIMIT和批量插入做语法上的转换
func (db *dbOracle) parseSql(sql string) string {
	//下面的正则表达式匹配出SELECT和INSERT的关键字后分别做不同的处理，如有LIMIT则将LIMIT的关键字也匹配出
	patten := `^\s*(?i)(SELECT)|(LIMIT\s*(\d+)\s*,\s*(\d+))`
	if gregex.IsMatchString(patten, sql) == false {
		//fmt.Println("not matched..")
		return sql
	}

	res, err := gregex.MatchAllString(patten, sql)
	if err != nil {
		//fmt.Println("MatchString error.", err)
		return ""
	}

	index := 0
	keyword := strings.TrimSpace(res[index][0])
	keyword = strings.ToUpper(keyword)

	index++
	switch keyword {
	case "SELECT":
		//不含LIMIT关键字则不处理
		if len(res) < 2 || (strings.HasPrefix(res[index][0], "LIMIT") == false && strings.HasPrefix(res[index][0], "limit") == false) {
			break
		}

		//取limit前面的字符串
		if gregex.IsMatchString("((?i)SELECT)(.+)((?i)LIMIT)", sql) == false {
			break
		}

		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
		}

		//取limit后面的取值范围
		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
			}
		}

		//也可以使用between,据说这种写法的性能会比between好点,里层SQL中的ROWNUM_ >= limit可以缩小查询后的数据集规模
		sql = fmt.Sprintf("SELECT * FROM (SELECT GFORM.*, ROWNUM ROWNUM_ FROM (%s %s) GFORM WHERE ROWNUM <= %d) WHERE ROWNUM_ >= %d", queryExpr[1], queryExpr[2], limit, first)
	}
	return sql
}

// 返回当前数据库所有的数据表名称
// TODO
func (bs *dbOracle) Tables() (tables []string, err error) {
	return
}

// 获得指定表表的数据结构，构造成map哈希表返回，其中键名为表字段名称，键值为字段数据结构.
func (db *dbOracle) TableFields(table string) (fields map[string]*TableField, err error) {
	// 缓存不存在时会查询数据表结构，缓存后不过期，直至程序重启(重新部署)
	v := db.cache.GetOrSetFunc("oracle_table_fields_"+table, func() interface{} {
		result := (Result)(nil)
		result, err = db.GetAll(fmt.Sprintf(`
		SELECT COLUMN_NAME AS FIELD, CASE DATA_TYPE 
		    WHEN 'NUMBER' THEN DATA_TYPE||'('||DATA_PRECISION||','||DATA_SCALE||')' 
			WHEN 'FLOAT' THEN DATA_TYPE||'('||DATA_PRECISION||','||DATA_SCALE||')' 
			ELSE DATA_TYPE||'('||DATA_LENGTH||')' END AS TYPE  
		FROM USER_TAB_COLUMNS WHERE TABLE_NAME = '%s' ORDER BY COLUMN_ID`, strings.ToUpper(table)))
		if err != nil {
			return nil
		}

		fields = make(map[string]*TableField)
		for i, m := range result {
			// ORACLE返回的值默认都是大写的，需要转为小写
			fields[strings.ToLower(m["FIELD"].String())] = &TableField{
				Index: i,
				Name:  strings.ToLower(m["FIELD"].String()),
				Type:  strings.ToLower(m["TYPE"].String()),
			}
		}
		return fields
	}, 0)
	if err == nil {
		fields = v.(map[string]*TableField)
	}
	return
}

//查询表的主键及唯一索引并存入缓存中
func (db *dbOracle) getTableUniqueIndex(table string) (fields map[string]map[string]string, err error) {
	table = strings.ToUpper(table)
	v := db.cache.GetOrSetFunc("table_unique_index_"+table, func() interface{} {
		res := (Result)(nil)
		res, err = db.GetAll(fmt.Sprintf(`
		SELECT INDEX_NAME,COLUMN_NAME,CHAR_LENGTH FROM USER_IND_COLUMNS 
		WHERE TABLE_NAME = '%s' 
		AND INDEX_NAME IN(SELECT INDEX_NAME FROM USER_INDEXES WHERE TABLE_NAME='%s' AND UNIQUENESS='UNIQUE') 
		ORDER BY INDEX_NAME,COLUMN_POSITION`, table, table))
		if err != nil {
			return nil
		}

		fields := make(map[string]map[string]string)
		for _, v := range res {
			mm := make(map[string]string)
			mm[v["COLUMN_NAME"].String()] = v["CHAR_LENGTH"].String()
			fields[v["INDEX_NAME"].String()] = mm
		}
		return fields
	}, 0)
	if err == nil {
		fields = v.(map[string]map[string]string)
	}
	return
}

// 支持insert、replace, save， ignore操作。
// 0: insert:  仅仅执行写入操作，如果存在冲突的主键或者唯一索引，那么报错返回;
// 1: replace: 如果数据存在(主键或者唯一索引)，那么删除后重新写入一条;
// 2: save:    如果数据存在(主键或者唯一索引)，那么更新，否则写入一条新数据;
// 3: ignore:  如果数据存在(主键或者唯一索引)，那么什么也不做,需ORACLE 11G以上版本
//
// 注意：对于replace/save/ignore操作只支持表中存在一个唯一索引或主键的情况，
// 如存在多个唯一索引或主键有可能会执行失败，因为这3种类型的操作需指定唯一索引，没有唯一索引情况下统一执行insert
//
// 参数data支持map/struct/*struct/slice类型，
// 当为slice(例如[]map/[]struct/[]*struct)类型时，batch参数生效，并自动切换为批量操作。
func (db *dbOracle) doInsert(link dbLink, table string, data interface{}, option int, batch ...int) (result sql.Result, err error) {
	var fields []string
	var values []string
	var params []interface{}
	var dataMap Map
	// 使用反射判断data数据类型，如果为slice类型，那么自动转为批量操作
	rv := reflect.ValueOf(data)
	kind := rv.Kind()
	if kind == reflect.Ptr {
		rv = rv.Elem()
		kind = rv.Kind()
	}
	switch kind {
	case reflect.Slice:
		fallthrough
	case reflect.Array:
		return db.db.doBatchInsert(link, table, data, option, batch...)
	case reflect.Map:
		fallthrough
	case reflect.Struct:
		dataMap = structToMap(data)
	default:
		return result, errors.New(fmt.Sprint("unsupported data type:", kind))
	}

	indexs := make([]string, 0)
	indexMap := make(map[string]string)
	indexExists := false
	if option != gINSERT_OPTION_DEFAULT {
		index, err := db.getTableUniqueIndex(table)
		if err != nil {
			return nil, err
		}

		if len(index) > 0 {
			for _, v := range index {
				for k, _ := range v {
					indexs = append(indexs, k)
				}
				indexMap = v
				indexExists = true
				break
			}
		}

	}

	subSqlStr := make([]string, 0)
	onStr := make([]string, 0)
	updateStr := make([]string, 0)

	charL, charR := db.db.getChars()
	for k, v := range dataMap {
		k = strings.ToUpper(k)

		//操作类型为REPLACE/SAVE时且存在唯一索引才使用merge，否则使用insert
		if (option == gINSERT_OPTION_REPLACE || option == gINSERT_OPTION_SAVE) && indexExists {
			fields = append(fields, tableAlias1+"."+charL+k+charR)
			values = append(values, tableAlias2+"."+charL+k+charR)
			params = append(params, convertParam(v))

			subSqlStr = append(subSqlStr, fmt.Sprintf("%s?%s %s", charL, charR, k))

			//merge中的on子句中由唯一索引组成,update子句中不含唯一索引
			if _, ok := indexMap[k]; ok {
				onStr = append(onStr, fmt.Sprintf("%s.%s = %s.%s ", tableAlias1, k, tableAlias2, k))
			} else {
				updateStr = append(updateStr, fmt.Sprintf("%s.%s = %s.%s ", tableAlias1, k, tableAlias2, k))
			}
		} else {
			fields = append(fields, charL+k+charR)
			values = append(values, "?")
			params = append(params, convertParam(v))
		}
	}

	if link == nil {
		if link, err = db.db.Master(); err != nil {
			return nil, err
		}
	}

	if indexExists && option != gINSERT_OPTION_DEFAULT {
		switch option {
		case gINSERT_OPTION_REPLACE:
			fallthrough
		case gINSERT_OPTION_SAVE:
			tmp := fmt.Sprintf("MERGE INTO %s %s USING(SELECT %s FROM DUAL) %s ON(%s) WHEN MATCHED THEN UPDATE SET %s WHEN NOT MATCHED THEN INSERT (%s) VALUES(%s)",
				table, tableAlias1, strings.Join(subSqlStr, ","), tableAlias2,
				strings.Join(onStr, "AND"), strings.Join(updateStr, ","), strings.Join(fields, ","), strings.Join(values, ","))
			return db.db.doExec(link, tmp, params...)
		case gINSERT_OPTION_IGNORE:
			return db.db.doExec(link,
				fmt.Sprintf("INSERT /*+ IGNORE_ROW_ON_DUPKEY_INDEX(%s(%s)) */ INTO %s(%s) VALUES(%s)",
					table, strings.Join(indexs, ","), table, strings.Join(fields, ","), strings.Join(values, ",")),
				params...)
		}
	}

	return db.db.doExec(link, fmt.Sprintf("INSERT INTO %s(%s) VALUES(%s)",
		table, strings.Join(fields, ","), strings.Join(values, ",")), params...)
}

// 批量写入数据, 参数list支持slice类型，例如: []map/[]struct/[]*struct。
func (db *dbOracle) doBatchInsert(link dbLink, table string, list interface{}, option int, batch ...int) (result sql.Result, err error) {
	var keys []string
	var values []string
	var params []interface{}
	listMap := (List)(nil)
	switch v := list.(type) {
	case Result:
		listMap = v.List()
	case Record:
		listMap = List{v.Map()}
	case List:
		listMap = v
	case Map:
		listMap = List{v}
	default:
		rv := reflect.ValueOf(list)
		kind := rv.Kind()
		if kind == reflect.Ptr {
			rv = rv.Elem()
			kind = rv.Kind()
		}
		switch kind {
		// 如果是slice，那么转换为List类型
		case reflect.Slice:
			fallthrough
		case reflect.Array:
			listMap = make(List, rv.Len())
			for i := 0; i < rv.Len(); i++ {
				listMap[i] = structToMap(rv.Index(i).Interface())
			}
		case reflect.Map:
			fallthrough
		case reflect.Struct:
			listMap = List{Map(structToMap(list))}
		default:
			return result, errors.New(fmt.Sprint("unsupported list type:", kind))
		}
	}
	// 判断长度
	if len(listMap) < 1 {
		return result, errors.New("empty data list")
	}
	if link == nil {
		if link, err = db.db.Master(); err != nil {
			return
		}
	}
	// 首先获取字段名称及记录长度
	holders := []string(nil)
	for k, _ := range listMap[0] {
		keys = append(keys, k)
		holders = append(holders, "?")
	}
	batchResult := new(batchSqlResult)
	charL, charR := db.db.getChars()
	keyStr := charL + strings.Join(keys, charL+","+charR) + charR
	valueHolderStr := strings.Join(holders, ",")

	// 当操作类型非insert时调用单笔的insert功能
	if option != gINSERT_OPTION_DEFAULT {
		for _, v := range listMap {
			r, err := db.doInsert(link, table, v, option, 1)
			if err != nil {
				return r, err
			}

			if n, err := r.RowsAffected(); err != nil {
				return r, err
			} else {
				batchResult.lastResult = r
				batchResult.rowsAffected += n
			}
		}
		return batchResult, nil
	}

	// 构造批量写入数据格式(注意map的遍历是无序的)
	batchNum := gDEFAULT_BATCH_NUM
	if len(batch) > 0 {
		batchNum = batch[0]
	}

	intoStr := make([]string, 0) //组装into语句
	for i := 0; i < len(listMap); i++ {
		for _, k := range keys {
			params = append(params, convertParam(listMap[i][k]))
		}
		values = append(values, valueHolderStr)

		intoStr = append(intoStr, fmt.Sprintf(" INTO %s(%s) VALUES(%s) ", table, keyStr, valueHolderStr))
		if len(intoStr) == batchNum {
			r, err := db.db.doExec(link, fmt.Sprintf("INSERT ALL   %s SELECT * FROM DUAL", strings.Join(intoStr, " ")), params...)
			if err != nil {
				return r, err
			}
			if n, err := r.RowsAffected(); err != nil {
				return r, err
			} else {
				batchResult.lastResult = r
				batchResult.rowsAffected += n
			}
			params = params[:0]
			intoStr = intoStr[:0]
		}
	}
	// 处理最后不构成指定批量的数据
	if len(intoStr) > 0 {
		r, err := db.db.doExec(link, fmt.Sprintf("INSERT ALL   %s SELECT * FROM DUAL", strings.Join(intoStr, " ")), params...)
		if err != nil {
			return r, err
		}
		if n, err := r.RowsAffected(); err != nil {
			return r, err
		} else {
			batchResult.lastResult = r
			batchResult.rowsAffected += n
		}
	}
	return batchResult, nil
}