// Copyright 2015 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 statements

import (
	"database/sql/driver"
	"errors"
	"fmt"
	"math/big"
	"reflect"
	"strings"
	"time"

	"xorm.io/builder"
	"xorm.io/xorm/v2/contexts"
	"xorm.io/xorm/v2/dialects"
	"xorm.io/xorm/v2/internal/convert"
	"xorm.io/xorm/v2/internal/json"
	"xorm.io/xorm/v2/internal/utils"
	"xorm.io/xorm/v2/schemas"
	"xorm.io/xorm/v2/tags"
)

var (
	// ErrConditionType condition type unsupported
	ErrConditionType = errors.New("Unsupported condition type")
	// ErrUnSupportedSQLType parameter of SQL is not supported
	ErrUnSupportedSQLType = errors.New("Unsupported sql type")
	// ErrUnSupportedType unsupported error
	ErrUnSupportedType = errors.New("Unsupported type error")
	// ErrTableNotFound table not found error
	ErrTableNotFound = errors.New("Table not found")
)

type join struct {
	op        string
	table     interface{}
	condition interface{}
	args      []interface{}
}

// Statement save all the sql info for executing SQL
type Statement struct {
	RefTable        *schemas.Table
	dialect         dialects.Dialect
	defaultTimeZone *time.Location
	tagParser       *tags.Parser
	Start           int
	LimitN          *int
	idParam         schemas.PK
	orderBy         []orderBy
	joins           []join
	GroupByStr      string
	HavingStr       string
	SelectStr       string
	useAllCols      bool
	AltTableName    string
	tableName       string
	RawSQL          string
	RawParams       []interface{}
	UseCascade      bool
	UseAutoJoin     bool
	StoreEngine     string
	Charset         string
	UseAutoTime     bool
	NoAutoCondition bool
	IsDistinct      bool
	IsForUpdate     bool
	TableAlias      string
	allUseBool      bool
	CheckVersion    bool
	unscoped        bool
	ColumnMap       columnMap
	OmitColumnMap   columnMap
	MustColumnMap   map[string]bool
	NullableMap     map[string]bool
	IncrColumns     exprParams
	DecrColumns     exprParams
	ExprColumns     exprParams
	cond            builder.Cond
	BufferSize      int
	Context         contexts.ContextCache
	LastError       error
}

// NewStatement creates a new statement
func NewStatement(dialect dialects.Dialect, tagParser *tags.Parser, defaultTimeZone *time.Location) *Statement {
	statement := &Statement{
		dialect:         dialect,
		tagParser:       tagParser,
		defaultTimeZone: defaultTimeZone,
	}
	statement.Reset()
	return statement
}

// SetTableName set table name
func (statement *Statement) SetTableName(tableName string) {
	statement.tableName = tableName
}

// GenRawSQL generates correct raw sql
func (statement *Statement) GenRawSQL() string {
	return statement.ReplaceQuote(statement.RawSQL)
}

// ReplaceQuote replace sql key words with quote
func (statement *Statement) ReplaceQuote(sql string) string {
	if sql == "" || statement.dialect.URI().DBType == schemas.MYSQL ||
		statement.dialect.URI().DBType == schemas.SQLITE {
		return sql
	}
	return statement.dialect.Quoter().Replace(sql)
}

// SetContextCache sets context cache
func (statement *Statement) SetContextCache(ctxCache contexts.ContextCache) {
	statement.Context = ctxCache
}

// Reset reset all the statement's fields
func (statement *Statement) Reset() {
	statement.RefTable = nil
	statement.Start = 0
	statement.LimitN = nil
	statement.ResetOrderBy()
	statement.UseCascade = true
	statement.joins = nil
	statement.GroupByStr = ""
	statement.HavingStr = ""
	statement.ColumnMap = columnMap{}
	statement.OmitColumnMap = columnMap{}
	statement.AltTableName = ""
	statement.tableName = ""
	statement.idParam = nil
	statement.RawSQL = ""
	statement.RawParams = make([]interface{}, 0)
	statement.UseAutoTime = true
	statement.NoAutoCondition = false
	statement.IsDistinct = false
	statement.IsForUpdate = false
	statement.TableAlias = ""
	statement.SelectStr = ""
	statement.allUseBool = false
	statement.useAllCols = false
	statement.MustColumnMap = make(map[string]bool)
	statement.NullableMap = make(map[string]bool)
	statement.CheckVersion = true
	statement.unscoped = false
	statement.IncrColumns = exprParams{}
	statement.DecrColumns = exprParams{}
	statement.ExprColumns = exprParams{}
	statement.cond = builder.NewCond()
	statement.BufferSize = 0
	statement.Context = nil
	statement.LastError = nil
}

// SQL adds raw sql statement
func (statement *Statement) SQL(query interface{}, args ...interface{}) *Statement {
	switch t := query.(type) {
	case (*builder.Builder):
		var err error
		statement.RawSQL, statement.RawParams, err = t.ToSQL()
		if err != nil {
			statement.LastError = err
		}
	case string:
		statement.RawSQL = t
		statement.RawParams = args
	default:
		statement.LastError = ErrUnSupportedSQLType
	}

	return statement
}

func (statement *Statement) quote(s string) string {
	return statement.dialect.Quoter().Quote(s)
}

// SetRefValue set ref value
func (statement *Statement) SetRefValue(v reflect.Value) error {
	var err error
	statement.RefTable, err = statement.tagParser.ParseWithCache(reflect.Indirect(v))
	if err != nil {
		return err
	}
	statement.tableName = dialects.FullTableName(statement.dialect, statement.tagParser.GetTableMapper(), v, true)
	return nil
}

func rValue(bean interface{}) reflect.Value {
	return reflect.Indirect(reflect.ValueOf(bean))
}

// SetRefBean set ref bean
func (statement *Statement) SetRefBean(bean interface{}) error {
	var err error
	statement.RefTable, err = statement.tagParser.ParseWithCache(rValue(bean))
	if err != nil {
		return err
	}
	statement.tableName = dialects.FullTableName(statement.dialect, statement.tagParser.GetTableMapper(), bean, true)
	return nil
}

func (statement *Statement) NeedTableName() bool {
	return len(statement.joins) > 0
}

// Incr Generate  "Update ... Set column = column + arg" statement
func (statement *Statement) Incr(column string, arg ...interface{}) *Statement {
	if len(arg) > 0 {
		statement.IncrColumns.Add(column, arg[0])
	} else {
		statement.IncrColumns.Add(column, 1)
	}
	return statement
}

// Decr Generate  "Update ... Set column = column - arg" statement
func (statement *Statement) Decr(column string, arg ...interface{}) *Statement {
	if len(arg) > 0 {
		statement.DecrColumns.Add(column, arg[0])
	} else {
		statement.DecrColumns.Add(column, 1)
	}
	return statement
}

// SetExpr Generate  "Update ... Set column = {expression}" statement
func (statement *Statement) SetExpr(column string, expression interface{}) *Statement {
	if e, ok := expression.(string); ok {
		statement.ExprColumns.Add(column, statement.dialect.Quoter().Replace(e))
	} else {
		statement.ExprColumns.Add(column, expression)
	}
	return statement
}

// ForUpdate generates "SELECT ... FOR UPDATE" statement
func (statement *Statement) ForUpdate() *Statement {
	statement.IsForUpdate = true
	return statement
}

// Nullable Update use only: update columns to null when value is nullable and zero-value
func (statement *Statement) Nullable(columns ...string) {
	newColumns := col2NewCols(columns...)
	for _, nc := range newColumns {
		statement.NullableMap[strings.ToLower(nc)] = true
	}
}

// Top generate LIMIT limit statement
func (statement *Statement) Top(limit int) *Statement {
	statement.Limit(limit)
	return statement
}

// Limit generate LIMIT start, limit statement
func (statement *Statement) Limit(limit int, start ...int) *Statement {
	statement.LimitN = &limit
	if len(start) > 0 {
		statement.Start = start[0]
	}
	return statement
}

// SetTable tempororily set table name, the parameter could be a string or a pointer of struct
func (statement *Statement) SetTable(tableNameOrBean interface{}) error {
	v := rValue(tableNameOrBean)
	t := v.Type()
	if t.Kind() == reflect.Struct {
		var err error
		statement.RefTable, err = statement.tagParser.ParseWithCache(v)
		if err != nil {
			return err
		}
	}

	statement.AltTableName = dialects.FullTableName(statement.dialect, statement.tagParser.GetTableMapper(), tableNameOrBean, true)
	return nil
}

// GroupBy generate "Group By keys" statement
func (statement *Statement) GroupBy(keys string) *Statement {
	statement.GroupByStr = statement.ReplaceQuote(keys)
	return statement
}

func (statement *Statement) writeGroupBy(w *builder.BytesWriter) error {
	if statement.GroupByStr == "" {
		return nil
	}
	_, err := fmt.Fprint(w, " GROUP BY ", statement.GroupByStr)
	return err
}

// Having generate "Having conditions" statement
func (statement *Statement) Having(conditions string) *Statement {
	statement.HavingStr = conditions
	return statement
}

func (statement *Statement) writeHaving(w *builder.BytesWriter) error {
	if statement.HavingStr == "" {
		return nil
	}
	_, err := fmt.Fprint(w, " HAVING ", statement.ReplaceQuote(statement.HavingStr))
	return err
}

// SetUnscoped always disable struct tag "deleted"
func (statement *Statement) SetUnscoped() *Statement {
	statement.unscoped = true
	return statement
}

// GetUnscoped return true if it's unscoped
func (statement *Statement) GetUnscoped() bool {
	return statement.unscoped
}

// GenIndexSQL generated create index SQL
func (statement *Statement) GenIndexSQL() []string {
	var sqls []string
	tbName := statement.TableName()
	for _, index := range statement.RefTable.Indexes {
		if index.Type == schemas.IndexType {
			sql := statement.dialect.CreateIndexSQL(tbName, index)
			sqls = append(sqls, sql)
		}
	}
	return sqls
}

// GenUniqueSQL generates unique SQL
func (statement *Statement) GenUniqueSQL() []string {
	var sqls []string
	tbName := statement.TableName()
	for _, index := range statement.RefTable.Indexes {
		if index.Type == schemas.UniqueType {
			sql := statement.dialect.CreateIndexSQL(tbName, index)
			sqls = append(sqls, sql)
		}
	}
	return sqls
}

// GenDelIndexSQL generate delete index SQL
func (statement *Statement) GenDelIndexSQL() []string {
	var sqls []string
	tbName := statement.TableName()
	idx := strings.Index(tbName, ".")
	if idx > -1 {
		tbName = tbName[idx+1:]
	}
	for _, index := range statement.RefTable.Indexes {
		sqls = append(sqls, statement.dialect.DropIndexSQL(tbName, index))
	}
	return sqls
}

func (statement *Statement) asDBCond(fieldValue reflect.Value, fieldType reflect.Type, col *schemas.Column, allUseBool, requiredField bool) (interface{}, bool, error) {
	switch fieldType.Kind() {
	case reflect.Ptr:
		if fieldValue.IsNil() {
			return nil, true, nil
		}
		return statement.asDBCond(fieldValue.Elem(), fieldType.Elem(), col, allUseBool, requiredField)
	case reflect.Bool:
		if allUseBool || requiredField {
			return fieldValue.Interface(), true, nil
		}
		// if a bool in a struct, it will not be as a condition because it default is false,
		// please use Where() instead
		return nil, false, nil
	case reflect.String:
		if !requiredField && fieldValue.String() == "" {
			return nil, false, nil
		}
		// for MyString, should convert to string or panic
		if fieldType.String() != reflect.String.String() {
			return fieldValue.String(), true, nil
		}
		return fieldValue.Interface(), true, nil
	case reflect.Int8, reflect.Int16, reflect.Int, reflect.Int32, reflect.Int64:
		if !requiredField && fieldValue.Int() == 0 {
			return nil, false, nil
		}
		return fieldValue.Interface(), true, nil
	case reflect.Float32, reflect.Float64:
		if !requiredField && fieldValue.Float() == 0.0 {
			return nil, false, nil
		}
		return fieldValue.Interface(), true, nil
	case reflect.Uint8, reflect.Uint16, reflect.Uint, reflect.Uint32, reflect.Uint64:
		if !requiredField && fieldValue.Uint() == 0 {
			return nil, false, nil
		}
		return fieldValue.Interface(), true, nil
	case reflect.Struct:
		if fieldType.ConvertibleTo(schemas.TimeType) {
			t := fieldValue.Convert(schemas.TimeType).Interface().(time.Time)
			if !requiredField && (t.IsZero() || !fieldValue.IsValid()) {
				return nil, false, nil
			}
			res, err := dialects.FormatColumnTime(statement.dialect, statement.defaultTimeZone, col, t)
			if err != nil {
				return nil, false, err
			}
			return res, true, nil
		} else if fieldType.ConvertibleTo(schemas.BigFloatType) {
			t := fieldValue.Convert(schemas.BigFloatType).Interface().(big.Float)
			v := t.String()
			if v == "0" {
				return nil, false, nil
			}
			return t.String(), true, nil
		} else if _, ok := reflect.New(fieldType).Interface().(convert.Conversion); ok {
			return nil, false, nil
		} else if valNul, ok := fieldValue.Interface().(driver.Valuer); ok {
			val, _ := valNul.Value()
			if val == nil && !requiredField {
				return nil, false, nil
			}
			return val, true, nil
		} else {
			if col.IsJSON {
				if col.SQLType.IsText() {
					bytes, err := json.DefaultJSONHandler.Marshal(fieldValue.Interface())
					if err != nil {
						return nil, false, err
					}
					return string(bytes), true, nil
				} else if col.SQLType.IsBlob() {
					var bytes []byte
					var err error
					bytes, err = json.DefaultJSONHandler.Marshal(fieldValue.Interface())
					if err != nil {
						return nil, false, err
					}
					return bytes, true, nil
				}
			} else {
				table, err := statement.tagParser.ParseWithCache(fieldValue)
				if err != nil {
					return fieldValue.Interface(), true, nil
				}

				if len(table.PrimaryKeys) == 1 {
					pkField := reflect.Indirect(fieldValue).FieldByName(table.PKColumns()[0].FieldName)
					// fix non-int pk issues
					// if pkField.Int() != 0 {
					if pkField.IsValid() && !utils.IsZero(pkField.Interface()) {
						return pkField.Interface(), true, nil
					}
					return nil, false, nil
				}
				return nil, false, fmt.Errorf("not supported %v as %v", fieldValue.Interface(), table.PrimaryKeys)
			}
		}
	case reflect.Array:
		return nil, false, nil
	case reflect.Slice, reflect.Map:
		if fieldValue == reflect.Zero(fieldType) {
			return nil, false, nil
		}
		if fieldValue.IsNil() || !fieldValue.IsValid() || fieldValue.Len() == 0 {
			return nil, false, nil
		}

		if col.SQLType.IsText() {
			bytes, err := json.DefaultJSONHandler.Marshal(fieldValue.Interface())
			if err != nil {
				return nil, false, err
			}
			return string(bytes), true, nil
		} else if col.SQLType.IsBlob() {
			var bytes []byte
			var err error
			if (fieldType.Kind() == reflect.Array || fieldType.Kind() == reflect.Slice) &&
				fieldType.Elem().Kind() == reflect.Uint8 {
				if fieldValue.Len() > 0 {
					return fieldValue.Bytes(), true, nil
				}
				return nil, false, nil
			}
			bytes, err = json.DefaultJSONHandler.Marshal(fieldValue.Interface())
			if err != nil {
				return nil, false, err
			}
			return bytes, true, nil
		}
		return nil, false, nil
	}
	return fieldValue.Interface(), true, nil
}

func (statement *Statement) buildConds2(table *schemas.Table, bean interface{},
	includeVersion bool, includeUpdated bool, includeNil bool,
	includeAutoIncr bool, allUseBool bool, useAllCols bool, unscoped bool,
	mustColumnMap map[string]bool, tableName, aliasName string, addedTableName bool,
) (builder.Cond, error) {
	var conds []builder.Cond
	for _, col := range table.Columns() {
		if !includeVersion && col.IsVersion {
			continue
		}
		if !includeUpdated && col.IsUpdated {
			continue
		}
		if !includeAutoIncr && col.IsAutoIncrement {
			continue
		}

		if col.IsJSON {
			continue
		}

		var colName string
		if addedTableName {
			nm := tableName
			if len(aliasName) > 0 {
				nm = aliasName
			}
			colName = statement.quote(nm) + "." + statement.quote(col.Name)
		} else {
			colName = statement.quote(col.Name)
		}

		fieldValuePtr, err := col.ValueOf(bean)
		if err != nil {
			continue
		} else if fieldValuePtr == nil {
			continue
		}

		if col.IsDeleted && !unscoped { // tag "deleted" is enabled
			conds = append(conds, statement.CondDeleted(col))
		}

		fieldValue := *fieldValuePtr
		if fieldValue.Interface() == nil {
			continue
		}

		if statement.dialect.URI().DBType == schemas.MSSQL && (col.SQLType.Name == schemas.Text ||
			col.SQLType.IsBlob() || col.SQLType.Name == schemas.TimeStampz) {
			if utils.IsValueZero(fieldValue) {
				continue
			}

			return nil, fmt.Errorf("column %s is a TEXT type with data %#v which cannot be as compare condition", col.Name, fieldValue.Interface())
		}

		requiredField := useAllCols
		if b, ok := getFlagForColumn(mustColumnMap, col); ok {
			if b {
				requiredField = true
			} else {
				continue
			}
		}

		fieldType := reflect.TypeOf(fieldValue.Interface())
		if fieldType.Kind() == reflect.Ptr {
			if fieldValue.IsNil() {
				if includeNil {
					conds = append(conds, builder.Eq{colName: nil})
				}
				continue
			} else if !fieldValue.IsValid() {
				continue
			} else {
				// dereference ptr type to instance type
				fieldValue = fieldValue.Elem()
				fieldType = reflect.TypeOf(fieldValue.Interface())
				requiredField = true
			}
		}

		val, ok, err := statement.asDBCond(fieldValue, fieldType, col, allUseBool, requiredField)
		if err != nil {
			return nil, err
		}
		if !ok {
			continue
		}

		conds = append(conds, builder.Eq{colName: val})
	}

	return builder.And(conds...), nil
}

// BuildConds builds condition
func (statement *Statement) BuildConds(table *schemas.Table, bean interface{}, includeVersion bool, includeUpdated bool, includeNil bool, includeAutoIncr bool, addedTableName bool) (builder.Cond, error) {
	return statement.buildConds2(table, bean, includeVersion, includeUpdated, includeNil, includeAutoIncr, statement.allUseBool, statement.useAllCols,
		statement.unscoped, statement.MustColumnMap, statement.TableName(), statement.TableAlias, addedTableName)
}

// MergeConds merge conditions from bean and id
func (statement *Statement) MergeConds(bean interface{}) error {
	if !statement.NoAutoCondition && statement.RefTable != nil {
		addedTableName := (len(statement.joins) > 0)
		autoCond, err := statement.BuildConds(statement.RefTable, bean, true, true, false, true, addedTableName)
		if err != nil {
			return err
		}
		statement.cond = statement.cond.And(autoCond)
	}

	return statement.ProcessIDParam()
}

func (statement *Statement) quoteColumnStr(columnStr string) string {
	columns := strings.Split(columnStr, ",")
	return statement.dialect.Quoter().Join(columns, ",")
}

// ConvertSQLOrArgs converts sql or args
func (statement *Statement) ConvertSQLOrArgs(sqlOrArgs ...interface{}) (string, []interface{}, error) {
	sql, args, err := statement.convertSQLOrArgs(sqlOrArgs...)
	if err != nil {
		return "", nil, err
	}
	return statement.ReplaceQuote(sql), args, nil
}

func (statement *Statement) convertSQLOrArgs(sqlOrArgs ...interface{}) (string, []interface{}, error) {
	switch sqlOrArgs[0].(type) {
	case string:
		if len(sqlOrArgs) > 1 {
			newArgs := make([]interface{}, 0, len(sqlOrArgs)-1)
			for _, arg := range sqlOrArgs[1:] {
				if v, ok := arg.(time.Time); ok {
					newArgs = append(newArgs, v.In(statement.defaultTimeZone).Format("2006-01-02 15:04:05"))
				} else if v, ok := arg.(*time.Time); ok && v != nil {
					newArgs = append(newArgs, v.In(statement.defaultTimeZone).Format("2006-01-02 15:04:05"))
				} else if v, ok := arg.(convert.ConversionTo); ok {
					r, err := v.ToDB()
					if err != nil {
						return "", nil, err
					}
					if r != nil {
						// for nvarchar column on mssql, bytes have to be converted as ucs-2 external of driver
						// for binary column, a string will be converted as bytes directly. So we have to
						// convert bytes as string
						if statement.dialect.URI().DBType == schemas.MSSQL {
							newArgs = append(newArgs, string(r))
						} else {
							newArgs = append(newArgs, r)
						}
					} else {
						newArgs = append(newArgs, nil)
					}
				} else {
					newArgs = append(newArgs, arg)
				}
			}
			return sqlOrArgs[0].(string), newArgs, nil
		}
		return sqlOrArgs[0].(string), sqlOrArgs[1:], nil
	case *builder.Builder:
		return sqlOrArgs[0].(*builder.Builder).ToSQL()
	case builder.Builder:
		bd := sqlOrArgs[0].(builder.Builder)
		return bd.ToSQL()
	}

	return "", nil, ErrUnSupportedType
}

func (statement *Statement) joinColumns(cols []*schemas.Column, includeTableName bool) string {
	colnames := make([]string, len(cols))
	for i, col := range cols {
		if includeTableName {
			colnames[i] = statement.quote(statement.TableName()) +
				"." + statement.quote(col.Name)
		} else {
			colnames[i] = statement.quote(col.Name)
		}
	}
	return strings.Join(colnames, ", ")
}

// CondDeleted returns the conditions whether a record is soft deleted.
func (statement *Statement) CondDeleted(col *schemas.Column) builder.Cond {
	colName := statement.quote(col.Name)
	if len(statement.joins) > 0 {
		var prefix string
		if statement.TableAlias != "" {
			prefix = statement.TableAlias
		} else {
			prefix = statement.TableName()
		}
		colName = statement.quote(prefix) + "." + statement.quote(col.Name)
	}
	cond := builder.NewCond()
	if col.SQLType.IsNumeric() {
		cond = builder.Eq{colName: 0}
	} else {
		// FIXME: mssql: The conversion of a nvarchar data type to a datetime data type resulted in an out-of-range value.
		if statement.dialect.URI().DBType != schemas.MSSQL {
			cond = builder.Eq{colName: utils.ZeroTime1}
		}
	}

	if col.Nullable {
		cond = cond.Or(builder.IsNull{colName})
	}

	return cond
}