package sharding

import (
	"context"
	"github.com/longbridgeapp/sqlparser"
	sqlparserX "github.com/uole/sqlparser"
	"gorm.io/gorm"
	"strconv"
)

type Scope struct {
	db    *gorm.DB
	stmt  *sqlparser.SelectStatement
	stmtX *sqlparserX.Select
}

func (scope *Scope) findValue(express sqlparser.Expr) (int, any) {
	var (
		vType int
		vData any
	)
	switch expr := express.(type) {
	case *sqlparser.BindExpr:
		vType = ValueTypeAny
		if len(scope.db.Statement.Vars) > expr.Pos {
			vData = scope.db.Statement.Vars[expr.Pos]
		} else {
			vType = ValueTypeNull
		}
	case *sqlparser.NumberLit:
		vType = ValueTypeNumber
		vData = expr.Value
	case *sqlparser.StringLit:
		vType = ValueTypeString
		vData = expr.Value
	case *sqlparser.BoolLit:
		vType = ValueTypeBoolean
		vData = expr.Value
	case *sqlparser.BlobLit:
		vType = ValueTypeString
		vData = expr.Value
	case *sqlparser.NullLit:
		vType = ValueTypeNull
	case *sqlparser.Range:
		arr := make([]any, 2)
		vType, arr[0] = scope.findValue(expr.X)
		vType, arr[1] = scope.findValue(expr.Y)
		vData = arr
	}
	return vType, vData
}

func (scope *Scope) findValueX(express *sqlparserX.SQLVal) (int, any) {
	var (
		vType int
		vData any
	)
	switch express.Type {
	case sqlparserX.IntVal:
		vType = ValueTypeNumber
		vData, _ = strconv.Atoi(string(express.Val))
	case sqlparserX.FloatVal:
		vType = ValueTypeNumber
		vData, _ = strconv.ParseFloat(string(express.Val), 64)
	case sqlparserX.ValArg:
		vType = ValueTypeAny
		pos, _ := strconv.Atoi(string(express.Val[2:]))
		if pos > 0 {
			pos = pos - 1
			if len(scope.db.Statement.Vars) > pos {
				vData = scope.db.Statement.Vars[pos]
			} else {
				vType = ValueTypeNull
			}
		} else {
			vType = ValueTypeNull
		}
	default:
		vType = ValueTypeString
		vData = string(express.Val)
	}
	return vType, vData
}

func (scope *Scope) recursiveFindX(expr sqlparserX.Expr, column string) (conditions []*ColumnCondition) {
	var (
		ok             bool
		andExpr        *sqlparserX.AndExpr
		orExpr         *sqlparserX.OrExpr
		parentExpr     *sqlparserX.ParenExpr
		comparisonExpr *sqlparserX.ComparisonExpr
		rangeExpr      *sqlparserX.RangeCond
		coumnExpr      *sqlparserX.ColName
		valueExpr      *sqlparserX.SQLVal
	)
	conditions = make([]*ColumnCondition, 0, 2)
	if comparisonExpr, ok = expr.(*sqlparserX.ComparisonExpr); ok {
		if coumnExpr, ok = comparisonExpr.Left.(*sqlparserX.ColName); !ok {
			return
		}
		if valueExpr, ok = comparisonExpr.Right.(*sqlparserX.SQLVal); !ok {
			return
		}
		if coumnExpr.Name.EqualString(column) {
			cond := &ColumnCondition{
				Name: coumnExpr.Name.String(),
			}
			vType, vData := scope.findValueX(valueExpr)
			switch comparisonExpr.Operator {
			case sqlparserX.LessThanStr, sqlparserX.LessEqualStr:
				cond.Value = newCondValue(vType, ValueOperaLess, vData)
			case sqlparserX.GreaterThanStr, sqlparserX.GreaterEqualStr:
				cond.Value = newCondValue(vType, ValueOperaGreater, vData)
			case sqlparserX.EqualStr:
				cond.Value = newCondValue(vType, ValueOperaEqual, vData)
			}
			if cond.Value != nil {
				conditions = append(conditions, cond)
			}
		}
	}

	if rangeExpr, ok = expr.(*sqlparserX.RangeCond); ok {
		if coumnExpr, ok = comparisonExpr.Left.(*sqlparserX.ColName); !ok {
			return
		}
		if coumnExpr.Name.EqualString(column) {
			vType := 0
			arr := make([]any, 2)
			if valueExpr, ok = rangeExpr.From.(*sqlparserX.SQLVal); ok {
				vType, arr[0] = scope.findValueX(valueExpr)
			}
			if valueExpr, ok = rangeExpr.To.(*sqlparserX.SQLVal); ok {
				vType, arr[1] = scope.findValueX(valueExpr)
			}
			conditions = append(conditions, &ColumnCondition{
				Name:  coumnExpr.Name.String(),
				Value: newCondValue(vType, ValueOperaRange, arr),
			})
		}
	}

	if andExpr, ok = expr.(*sqlparserX.AndExpr); ok {
		if andExpr.Left != nil {
			conditions = append(conditions, scope.recursiveFindX(andExpr.Left, column)...)
		}
		if andExpr.Right != nil {
			conditions = append(conditions, scope.recursiveFindX(andExpr.Right, column)...)
		}
	}
	if orExpr, ok = expr.(*sqlparserX.OrExpr); ok {
		if orExpr.Left != nil {
			conditions = append(conditions, scope.recursiveFindX(orExpr.Left, column)...)
		}
		if orExpr.Right != nil {
			conditions = append(conditions, scope.recursiveFindX(orExpr.Right, column)...)
		}
	}
	if parentExpr, ok = expr.(*sqlparserX.ParenExpr); ok {
		if parentExpr.Expr != nil {
			conditions = append(conditions, scope.recursiveFindX(parentExpr.Expr, column)...)
		}
	}
	return conditions
}

func (scope *Scope) recursiveFind(expr sqlparser.Expr, column string) []*ColumnCondition {
	var (
		ok         bool
		identExpr  *sqlparser.Ident
		binaryExpr *sqlparser.BinaryExpr
		parentExpr *sqlparser.ParenExpr
		conditions []*ColumnCondition
	)
	conditions = make([]*ColumnCondition, 0, 2)
	if parentExpr, ok = expr.(*sqlparser.ParenExpr); ok {
		if parentExpr.X != nil {
			if _, ok = parentExpr.X.(*sqlparser.BinaryExpr); ok {
				conditions = append(conditions, scope.recursiveFind(parentExpr.X, column)...)
			}
			if _, ok = parentExpr.X.(*sqlparser.ParenExpr); ok {
				conditions = append(conditions, scope.recursiveFind(parentExpr.X, column)...)
			}
		}
	}

	if binaryExpr, ok = expr.(*sqlparser.BinaryExpr); ok {
		if binaryExpr.X != nil {
			if identExpr, ok = binaryExpr.X.(*sqlparser.Ident); ok {
				if identExpr.Name == column {
					cond := &ColumnCondition{
						Name: identExpr.Name,
					}
					vType, vData := scope.findValue(binaryExpr.Y)
					switch binaryExpr.Op {
					case sqlparser.LT, sqlparser.LE:
						cond.Value = newCondValue(vType, ValueOperaLess, vData)
					case sqlparser.GT, sqlparser.GE:
						cond.Value = newCondValue(vType, ValueOperaGreater, vData)
					case sqlparser.RANGE, sqlparser.BETWEEN:
						cond.Value = newCondValue(vType, ValueOperaRange, vData)
					case sqlparser.EQ:
						cond.Value = newCondValue(vType, ValueOperaEqual, vData)
					}
					if cond.Value != nil {
						conditions = append(conditions, cond)
					}
				}
			} else {
				if _, ok = binaryExpr.X.(*sqlparser.BinaryExpr); ok {
					conditions = append(conditions, scope.recursiveFind(binaryExpr.X, column)...)
				}
				if _, ok = binaryExpr.X.(*sqlparser.ParenExpr); ok {
					conditions = append(conditions, scope.recursiveFind(binaryExpr.X, column)...)
				}
			}
		}

		if binaryExpr.Y != nil {
			if _, ok = binaryExpr.Y.(*sqlparser.BinaryExpr); ok {
				conditions = append(conditions, scope.recursiveFind(binaryExpr.Y, column)...)
			}
		}
	}

	return conditions
}

func (scope *Scope) DB() *gorm.DB {
	return scope.db
}

func (scope *Scope) Context() context.Context {
	return scope.db.Statement.Context
}

func (scope *Scope) FindCondition(column string) []*ColumnCondition {
	if scope.stmtX != nil {
		if scope.stmtX.Where == nil {
			return []*ColumnCondition{}
		}
		return scope.recursiveFindX(scope.stmtX.Where.Expr, column)
	}
	return scope.recursiveFind(scope.stmt.Condition, column)
}

func (scope *Scope) FindColumnValues(column string) []any {
	result := make([]any, 0)
	conditions := scope.FindCondition(column)
	if len(conditions) == 0 {
		return result
	}
	for _, cond := range conditions {
		if cond.Value.Opera() == ValueOperaGreater {
			if len(result) == 0 {
				result = make([]any, 2)
			}
			result[0] = cond.Value.Value()
		}

		if cond.Value.Opera() == ValueOperaLess {
			if len(result) == 0 {
				result = make([]any, 2)
			}
			result[1] = cond.Value.Value()
		}

		if cond.Value.Opera() == ValueOperaEqual {
			result = append(result, cond.Value.Value())
			break
		}

		if cond.Value.Opera() == ValueOperaRange {
			if vs, ok := cond.Value.Value().([]any); ok {
				if len(vs) == 2 {
					if len(result) == 0 {
						result = make([]any, 2)
					}
					result[0] = vs[0]
					result[1] = vs[1]
				}
			}
			break
		}
	}
	return result
}