package dpsapi

import (
	"errors"
	"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 {
	selectExpr []string
	from       string
	where      []string
	limit      int
	offset     int
}

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
			tableFmtCtx := tree.NewFmtCtx(tree.FmtSimple)
			realNode.Table.Format(tableFmtCtx)
			clause.table = tableFmtCtx.String()

			// 解析rows
			values := make([]clauseTableRowValue, 0)

			rowsStatement, err := parser.Parse(realNode.Rows.String())
			if err != nil {
				walkFuncErr = err
				return true
			}

			var rowsWalkFuncErr error
			funcStringParams := make([]string, 0)

			rowsWalker := &walk.AstWalker{Fn: func(ctx interface{}, node interface{}) (stop bool) {
				switch rowsNode := node.(type) {
				case *tree.FuncExpr:
					// 函数类型
					value, kind, err := evaluateFuncExpr(rowsNode, nil, &funcStringParams)
					if err != nil {
						rowsWalkFuncErr = err
						return true
					}

					values = append(values, clauseTableRowValue{
						kind:  kind,
						value: value,
					})
				case *tree.DBool:
					// 布尔类型
					stringValue := rowsNode.String()
					if !canSkipValueInThisContext(&funcStringParams, stringValue) {
						if stringValue == "false" {
							values = append(values, clauseTableRowValue{
								kind:  clauseTableRowValueKindBool,
								value: false,
							})
						} else if stringValue == "true" {
							values = append(values, clauseTableRowValue{
								kind:  clauseTableRowValueKindBool,
								value: true,
							})
						} else {
							rowsWalkFuncErr = errors.New("不支持的bool值")
							return true
						}
					}
				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
					stringValue := rowsNode.String()
					if !canSkipValueInThisContext(&funcStringParams, stringValue) {
						values = append(values, clauseTableRowValue{
							kind:  clauseTableRowValueKindString,
							value: rowsNode.RawString(),
						})
					}
				case *tree.NumVal:
					// 数值类型，可以是整形或浮点型
					stringValue := rowsNode.String()
					if !canSkipValueInThisContext(&funcStringParams, stringValue) {
						numKind := rowsNode.Kind()
						if numKind == constant.Int {
							valueUint64, err := strconv.ParseUint(rowsNode.String(), 10, 64)
							if err != nil {
								rowsWalkFuncErr = err
								return true
							}

							values = append(values, clauseTableRowValue{
								kind:  clauseTableRowValueKindUint64,
								value: valueUint64,
							})
						} else if numKind == constant.Float {
							valueFloat64, err := strconv.ParseFloat(rowsNode.String(), 64)
							if err != nil {
								rowsWalkFuncErr = err
								return true
							}

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

				return false
			}}

			_, err = rowsWalker.Walk(rowsStatement, nil)
			if err != nil {
				walkFuncErr = err
				return true
			}

			if rowsWalkFuncErr != nil {
				walkFuncErr = rowsWalkFuncErr
				return true
			}

			// 组装columnValues
			tableRows := make(map[string]clauseTableRowValue)
			for i, column := range realNode.Columns.ToStrings() {
				tableRows[column] = values[i]
			}

			clause.tableRow = tableRows

			return false
		},
	}

	_, 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
			tableFmtCtx := tree.NewFmtCtx(tree.FmtSimple)
			realNode.Table.Format(tableFmtCtx)
			clause.table = tableFmtCtx.String()

			// 获取where
			clause.where = realNode.Where.Expr.String()

			return false
		},
	}

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

	if walkFuncErr != nil {
		return nil, walkFuncErr
	}

	return clause, nil
}

func updateWalk(sql string) (*insertClause, error) {
	return nil, nil
}

func selectWalk(sql string) (*insertClause, error) {
	return nil, nil
}

func evaluateFuncExpr(expr *tree.FuncExpr, funcName *string, stringParams *[]string) (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)")
		}

		timeStr := expr.Exprs[0].String()
		timeFormat := expr.Exprs[1].String()

		if funcName != nil {
			*funcName = "parse_time"
		}

		if stringParams != nil {
			*stringParams = append(*stringParams, timeStr, timeFormat)
		}

		parsedTime, err := time.ParseInLocation(timeFormat, timeStr, 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")
	}
}

func canSkipValueInThisContext(stringParams *[]string, stringValue string) bool {
	if stringParams == nil || *stringParams == nil || len(*stringParams) == 0 {
		return false
	}

	if (*stringParams)[0] == stringValue {
		*stringParams = (*stringParams)[1:]
		return true
	}

	return false
}