package api

import (
	"errors"
	"fmt"
	"github.com/auxten/postgresql-parser/pkg/sql/parser"
	"github.com/auxten/postgresql-parser/pkg/sql/sem/tree"
	"github.com/auxten/postgresql-parser/pkg/walk"
	"go/constant"
	"strconv"
	"strings"
	"time"
)

const (
	clauseTableRowValueKindTime int = iota + 1
	clauseTableRowValueKindBool
	clauseTableRowValueKindString
	clauseTableRowValueKindUint64
	clauseTableRowValueKindFloat64
)

type clauseTableRowValue struct {
	kind  int
	value any
}

type insertClause struct {
	table    string
	tableRow map[string]clauseTableRowValue
}

type deleteClause struct {
	table string
	where string
}

type updateClause struct {
	table       string
	where       string
	newTableRow map[string]clauseTableRowValue
}

type selectClause struct {
	table        string
	fromSubQuery string
	selectClause string
	where        string
	orderBy      string
	groupBy      string
	having       string
	pageNo       int
	pageSize     int
}

// 调试很重要的函数，可以看到一个节点的实际类型以及包含字段的类型
func printNode(node any) {
	fmt.Printf("%+#v\n", node)
}

func parseSql(sqlStr string) ([]any, error) {
	sqls := strings.Split(sqlStr, ";")

	sqlClauses := make([]any, 0)

	for _, sql := range sqls {
		trimSQL := strings.TrimSpace(sql)
		upperTrimSQL := strings.ToUpper(trimSQL)

		var clause any

		if strings.HasPrefix(upperTrimSQL, "INSERT") {
			innerClause, err := insertWalk(sql)
			if err != nil {
				return nil, err
			}

			clause = innerClause
		} else if strings.HasPrefix(upperTrimSQL, "DELETE") {
			innerClause, err := deleteWalk(sql)
			if err != nil {
				return nil, err
			}

			clause = innerClause
		} else if strings.HasPrefix(upperTrimSQL, "UPDATE") {
			innerClause, err := updateWalk(sql)
			if err != nil {
				return nil, err
			}

			clause = innerClause
		} else if strings.HasPrefix(upperTrimSQL, "SELECT") {
			innerClause, err := selectWalk(sql)
			if err != nil {
				return nil, err
			}

			clause = innerClause
		}

		sqlClauses = append(sqlClauses, clause)
	}

	return sqlClauses, nil
}

func insertWalk(sql string) (*insertClause, error) {
	clause := new(insertClause)

	stmts, err := parser.Parse(sql)
	if err != nil {
		return nil, err
	}

	var walkFuncErr error

	w := &walk.AstWalker{
		Fn: func(ctx interface{}, node interface{}) (stop bool) {
			realNode := node.(*tree.Insert)

			// 获取table
			tableName, err := parseTableExpr(realNode.Table)
			if err != nil {
				walkFuncErr = err
				return true
			}

			clause.table = tableName

			// 获取table row
			clause.tableRow = make(map[string]clauseTableRowValue)
			columns := realNode.Columns.ToStrings()
			valuesClause := realNode.Rows.Select.(*tree.ValuesClause)
			for _, row := range valuesClause.Rows {
				for i, column := range row {
					columnValue, err := parseExpr(column)
					if err != nil {
						walkFuncErr = err
						return true
					}

					clause.tableRow[columns[i]] = *columnValue
				}
			}

			return true
		},
	}

	_, err = w.Walk(stmts, nil)
	if err != nil {
		return nil, err
	}

	if walkFuncErr != nil {
		return nil, walkFuncErr
	}

	return clause, nil
}

func deleteWalk(sql string) (*deleteClause, error) {
	clause := new(deleteClause)

	stmts, err := parser.Parse(sql)
	if err != nil {
		return nil, err
	}

	var walkFuncErr error

	w := &walk.AstWalker{
		Fn: func(ctx interface{}, node interface{}) (stop bool) {
			realNode := node.(*tree.Delete)

			// 获取table
			tableName, err := parseTableExpr(realNode.Table)
			if err != nil {
				walkFuncErr = err
				return true
			}

			clause.table = tableName

			// 获取where
			clause.where = parseWhere(realNode.Where)

			return true
		},
	}

	_, err = w.Walk(stmts, nil)
	if err != nil {
		return nil, err
	}

	if walkFuncErr != nil {
		return nil, walkFuncErr
	}

	return clause, nil
}

func updateWalk(sql string) (*updateClause, error) {
	clause := new(updateClause)

	stmts, err := parser.Parse(sql)
	if err != nil {
		return nil, err
	}

	var walkFuncErr error

	w := &walk.AstWalker{
		Fn: func(ctx interface{}, node interface{}) (stop bool) {
			realNode := node.(*tree.Update)

			// 获取table
			tableName, err := parseTableExpr(realNode.Table)
			if err != nil {
				walkFuncErr = err
				return true
			}

			clause.table = tableName

			// 获取where
			clause.where = parseWhere(realNode.Where)

			// 获取table row
			clause.newTableRow = make(map[string]clauseTableRowValue)
			for _, expr := range realNode.Exprs {
				value, err := parseExpr(expr.Expr)
				if err != nil {
					walkFuncErr = err
					return true
				}

				clause.newTableRow[fmt.Sprint(expr.Names[0])] = *value
			}

			return true
		},
	}

	_, err = w.Walk(stmts, nil)
	if err != nil {
		return nil, err
	}

	if walkFuncErr != nil {
		return nil, walkFuncErr
	}

	return clause, nil
}

func selectWalk(sql string) (*selectClause, error) {
	clause := new(selectClause)

	stmts, err := parser.Parse(sql)
	if err != nil {
		return nil, err
	}

	var walkFuncErr error

	w := &walk.AstWalker{
		Fn: func(ctx interface{}, node interface{}) (stop bool) {
			realNode := node.(*tree.Select)
			nodeSelectClause := realNode.Select.(*tree.SelectClause)

			// select
			clause.selectClause = parseSelect(nodeSelectClause.Exprs)
			if clause.selectClause == "*" {
				clause.selectClause = ""
			}

			// from
			asFromSubQuery, from, err := parseFrom(&nodeSelectClause.From)
			if err != nil {
				walkFuncErr = err
				return true
			}

			if asFromSubQuery {
				clause.fromSubQuery = from
			} else {
				clause.table = from
			}

			// where
			if nodeSelectClause.Where != nil {
				clause.where = parseWhere(nodeSelectClause.Where)
			}

			// order by
			if realNode.OrderBy != nil {
				clause.orderBy = parseOrderBy(realNode.OrderBy)
			}

			// limit
			if realNode.Limit != nil {
				pageNo, pageSize, err := parseLimit(realNode.Limit)
				if err != nil {
					walkFuncErr = err
					return true
				}

				clause.pageNo = pageNo
				clause.pageSize = pageSize
			}

			// group by
			if nodeSelectClause.GroupBy != nil {
				clause.groupBy = parseGroupBy(nodeSelectClause.GroupBy)
			}

			// having
			if nodeSelectClause.Having != nil {
				clause.having = parseWhere(nodeSelectClause.Having)
			}

			return true
		},
	}

	_, err = w.Walk(stmts, nil)
	if err != nil {
		return nil, err
	}

	if walkFuncErr != nil {
		return nil, walkFuncErr
	}

	return clause, nil
}

func parseTableExpr(tableExpr tree.TableExpr) (string, error) {
	switch table := tableExpr.(type) {
	case *tree.TableName:
		return table.String(), nil
	case *tree.AliasedTableExpr:
		return table.String(), nil
	default:
		return "", errors.New("不支持的TableExpr")
	}
}

func parseSelect(selectExprs tree.SelectExprs) string {
	selectFmtCtx := tree.NewFmtCtx(tree.FmtBareStrings)
	selectExprs.Format(selectFmtCtx)
	return selectFmtCtx.String()
}

func parseFrom(from *tree.From) (bool, string, error) {
	switch fromTable := from.Tables[0].(type) {
	case *tree.JoinTableExpr:
		return true, fromTable.String(), nil
	case *tree.AliasedTableExpr:
		_, ok := fromTable.Expr.(*tree.Subquery)
		if ok {
			return true, fromTable.String(), nil
		} else {
			return false, fromTable.String(), nil
		}
	default:
		return false, "", errors.New("不支持的From类型")
	}
}

func parseWhere(where *tree.Where) string {
	return where.Expr.String()
}

func parseOrderBy(orderBy tree.OrderBy) string {
	orderByFmtCtx := tree.NewFmtCtx(tree.FmtBareStrings)
	orderBy[0].Format(orderByFmtCtx)
	return orderByFmtCtx.String()
}

func parseLimit(limit *tree.Limit) (int, int, error) {
	pageNo, err := strconv.Atoi(limit.Offset.String())
	if err != nil {
		return 0, 0, err
	}

	pageSize, err := strconv.Atoi(limit.Count.String())
	if err != nil {
		return 0, 0, err
	}

	return pageNo, pageSize, nil
}

func parseGroupBy(groupBy tree.GroupBy) string {
	groupBySlice := make([]string, 0)

	for _, groupExpr := range groupBy {
		groupBySlice = append(groupBySlice, groupExpr.String())
	}

	return strings.Join(groupBySlice, ",")
}

func parseExpr(valueExpr tree.Expr) (*clauseTableRowValue, error) {
	switch realColumn := valueExpr.(type) {
	case *tree.FuncExpr:
		// 函数类型
		value, kind, err := evaluateFuncExpr(realColumn)
		if err != nil {
			return nil, err
		}

		return &clauseTableRowValue{
			kind:  kind,
			value: value,
		}, nil
	case *tree.DBool:
		// 布尔类型
		var boolValue bool
		stringValue := realColumn.String()
		if stringValue == "true" {
			boolValue = true
		}

		return &clauseTableRowValue{
			kind:  clauseTableRowValueKindBool,
			value: boolValue,
		}, nil
	case *tree.StrVal:
		// 字符串类型或者函数参数是字符串的类型，这里通过比较字符串value，排除了函数参数类型
		return &clauseTableRowValue{
			kind:  clauseTableRowValueKindString,
			value: realColumn.RawString(),
		}, nil
	case *tree.NumVal:
		// 数值类型，可以是整形或浮点型
		numKind := realColumn.Kind()
		if numKind == constant.Int {
			valueUint64, err := strconv.ParseUint(realColumn.String(), 10, 64)
			if err != nil {
				return nil, err
			}

			return &clauseTableRowValue{
				kind:  clauseTableRowValueKindUint64,
				value: valueUint64,
			}, nil
		} else if numKind == constant.Float {
			valueFloat64, err := strconv.ParseFloat(realColumn.String(), 64)
			if err != nil {
				return nil, err
			}

			return &clauseTableRowValue{
				kind:  clauseTableRowValueKindFloat64,
				value: valueFloat64,
			}, nil
		} else {
			return nil, errors.New("不支持的数值类型")
		}
	case *tree.UnresolvedName:
		return nil, errors.New("存在无法解析的名字，是否应该使用单引号")
	default:
		return nil, errors.New("未支持的数据类型")
	}
}

func evaluateFuncExpr(expr *tree.FuncExpr) (any, int, error) {
	if strings.HasPrefix(expr.String(), "parse_time") {
		if expr.Exprs == nil || len(expr.Exprs) != 2 {
			return nil, 0, errors.New("parse_time(time_str, time_format)")
		}

		timeStrValue, err := parseExpr(expr.Exprs[0])
		if err != nil {
			return nil, 0, err
		}

		if timeStrValue.kind != clauseTableRowValueKindString {
			return nil, 0, errors.New("时间字符串不是字符串类型")
		}

		timeFormatValue, err := parseExpr(expr.Exprs[1])
		if err != nil {
			return nil, 0, err
		}

		if timeFormatValue.kind != clauseTableRowValueKindString {
			return nil, 0, errors.New("时间格式不是字符串类型")
		}

		parsedTime, err := time.ParseInLocation(timeFormatValue.value.(string), timeStrValue.value.(string), time.Local)
		if err != nil {
			return nil, 0, err
		}

		return parsedTime, clauseTableRowValueKindTime, nil
	} else {
		return nil, 0, errors.New("不支持的函数")
	}
}