package data_query

import (
	"errors"
	"fmt"
	"math"
	"regexp"
	"strings"

	"github.com/JetBrains/ij-perf-report-aggregator/pkg/http-error"
	"github.com/valyala/fastjson"
)

// https://clickhouse.yandex/docs/en/query_language/syntax/#syntax-identifiers
var reFieldName = regexp.MustCompile(`^[a-zA-Z_]\w*$`)

// opposite to reFieldName, dot is supported for nested fields
var (
	reNestedFieldName = regexp.MustCompile(`^[a-zA-Z_][.\da-zA-Z_]*$`)
	reMetricName      = regexp.MustCompile(`^[a-zA-Z\d _]+$`)
)

// add ().space,'*
var reAggregator = regexp.MustCompile(`^[a-zA-Z_'(][\da-zA-Z_(). ,'*@<>\-/+]*$`)

// for db name the same validation rules as for field name
var reDbName = reFieldName

var queryParsers fastjson.ParserPool

func isValidFieldName(v string) bool {
	return reFieldName.MatchString(v)
}

func isValidFilterFieldName(v string) bool {
	return reNestedFieldName.MatchString(v)
}

func readQuery(s []byte) ([]Query, error) {
	parser := queryParsers.Get()
	defer queryParsers.Put(parser)

	value, err := parser.ParseBytes(s)
	if err != nil {
		return nil, fmt.Errorf("cannot parse query: %w", err)
	}

	var queries []Query

	if value.Type() == fastjson.TypeArray {
		for _, v := range value.GetArray() {
			query, err := readQueryValue(v)
			if err != nil {
				return queries, err
			}

			queries = append(queries, *query)
		}
	} else {
		query, err := readQueryValue(value)
		if err != nil {
			return queries, err
		}

		queries = append(queries, *query)
	}

	return queries, nil
}

func readQueryValue(value *fastjson.Value) (*Query, error) {
	query := &Query{
		Database: string(value.GetStringBytes("db")),
		Table:    string(value.GetStringBytes("table")),
		Flat:     value.GetBool("flat"),
	}

	switch {
	case query.Database == "":
		query.Database = "default"
	case !reDbName.MatchString(query.Database):
		return nil, http_error.NewHttpError(400, fmt.Sprintf("Database name %s contains illegal chars", query.Database))
	case query.Table != "" && !reDbName.MatchString(query.Table):
		return nil, http_error.NewHttpError(400, fmt.Sprintf("Table name %s contains illegal chars", query.Table))
	}

	err := readDimensions(value.GetArray("fields"), &query.Fields)
	if err != nil {
		return nil, err
	}

	err = readFilters(value.GetArray("filters"), query)
	if err != nil {
		return nil, err
	}

	orderValue := value.Get("order")
	if orderValue == nil {
		return nil, http_error.NewHttpError(400, "order is missing")
	}
	if orderValue.Type() == fastjson.TypeString {
		field := string(orderValue.GetStringBytes())
		if !reNestedFieldName.MatchString(field) {
			return nil, http_error.NewHttpError(400, fmt.Sprintf("Order %s is not a valid field name", field))
		}
		query.Order = []string{field}
	} else {
		for _, v := range value.GetArray("order") {
			field := string(v.GetStringBytes())
			if !reNestedFieldName.MatchString(field) {
				return nil, http_error.NewHttpError(400, fmt.Sprintf("Order %s is not a valid field name", field))
			}
			query.Order = append(query.Order, field)
		}
	}

	query.Aggregator = string(value.GetStringBytes("aggregator"))
	if query.Aggregator != "" && !reAggregator.MatchString(query.Aggregator) {
		return nil, http_error.NewHttpError(400, fmt.Sprintf("Aggregator %s contains illegal chars", query.Aggregator))
	}

	err = readDimensions(value.GetArray("dimensions"), &query.Dimensions)
	if err != nil {
		return nil, err
	}

	query.TimeDimensionFormat = string(value.GetStringBytes("timeDimensionFormat"))
	if query.Aggregator != "" && !reAggregator.MatchString(query.Aggregator) {
		return nil, http_error.NewHttpError(400, fmt.Sprintf("timeDimensionFormat %s contains illegal chars", query.TimeDimensionFormat))
	}
	return query, nil
}

func readDimensions(list []*fastjson.Value, result *[]QueryDimension) error {
	for _, v := range list {
		t, err := readDimension(v)
		if err != nil {
			return err
		}

		if t.Sql != "" && !reAggregator.MatchString(t.Sql) {
			return http_error.NewHttpError(400, fmt.Sprintf("Dimension SQL %s contains illegal chars", t.Sql))
		}
		if t.resultPropertyName != "" && !isValidFieldName(t.resultPropertyName) {
			return http_error.NewHttpError(400, fmt.Sprintf("resultPropertyName %s is not a valid field name", t.Name))
		}
		*result = append(*result, *t)
	}
	return nil
}

func readDimension(v *fastjson.Value) (*QueryDimension, error) {
	var t QueryDimension
	if v.Type() == fastjson.TypeString {
		t = QueryDimension{
			Name: string(v.GetStringBytes()),
		}
	} else {
		subNameValue := v.Get("subName")
		if subNameValue == nil {
			t = QueryDimension{
				Name: string(v.GetStringBytes("n")),
				Sql:  string(v.GetStringBytes("sql")),
			}
		} else {
			arrayJoin := string(v.GetStringBytes("n"))
			t = QueryDimension{
				Name:               arrayJoin + "." + string(subNameValue.GetStringBytes()),
				arrayJoin:          arrayJoin,
				Sql:                string(v.GetStringBytes("sql")),
				resultPropertyName: string(v.GetStringBytes("resultKey")),
			}

			if !reNestedFieldName.MatchString(t.Name) {
				return nil, http_error.NewHttpError(400, fmt.Sprintf("Name %s is not a valid field name", t.Name))
			}
			if !isValidFieldName(t.arrayJoin) {
				return nil, http_error.NewHttpError(400, fmt.Sprintf("subName %s is not a valid field name", t.Name))
			}

			return &t, nil
		}
	}

	t.resultPropertyName = string(v.GetStringBytes("resultKey"))

	qualifierDotIndex := strings.IndexRune(t.Name, '.')
	if qualifierDotIndex != -1 {
		t.metricPath = t.Name[0:qualifierDotIndex]
		t.metricName = t.Name[qualifierDotIndex+1:]
		t.metricValueName = 'd'

		metricNameLength := len(t.metricName)
		if metricNameLength > 2 && t.metricName[metricNameLength-2] == '.' {
			t.metricValueName = rune(t.metricName[metricNameLength-1])
			t.metricName = t.metricName[:metricNameLength-2]
		}

		if t.resultPropertyName == "" {
			t.resultPropertyName = strings.ReplaceAll(t.metricName, " ", "_")
		}

		if !isValidFieldName(t.metricPath) || !reMetricName.MatchString(t.metricName) {
			return nil, http_error.NewHttpError(400, fmt.Sprintf("Name %s is not a valid field name", t.Name))
		}
	}
	return &t, nil
}

func readFilters(list []*fastjson.Value, query *Query) error {
	for _, v := range list {
		t := QueryFilter{
			Field:    string(v.GetStringBytes("f")),
			Sql:      string(v.GetStringBytes("q")),
			Operator: string(v.GetStringBytes("o")),
			Split:    false,
		}

		if t.Sql == "" {
			t.Sql = string(v.GetStringBytes("sql"))
		}

		value := v.Get("v")
		t.Split = v.GetBool("s")
		if value == nil {
			value = v.Get("value")
		}

		if !isValidFilterFieldName(t.Field) && t.Sql == "" {
			return http_error.NewHttpError(400, t.Field+" is not a valid filter field name")
		}

		if t.Sql == "" && value == nil {
			return errors.New("filter value is not specified")
		}
		if t.Sql == "" {
			switch value.Type() {
			case fastjson.TypeString:
				t.Value = string(value.GetStringBytes())
			case fastjson.TypeNumber:
				number, err := value.Float64()
				if err != nil {
					return fmt.Errorf("cannot parse filter value %s: %w", value, err)
				}
				if number == math.Trunc(number) {
					// convert to int (to be able to use time unix timestamps from client side)
					t.Value = int(number)
				} else {
					t.Value = number
				}
			case fastjson.TypeArray:
				t.Value = readArray(value)
			case fastjson.TypeFalse:
				t.Value = value.GetBool()
			case fastjson.TypeTrue:
				t.Value = value.GetBool()
			default:
				return fmt.Errorf("filter value %v is not supported", value)
			}

			if t.Operator == "" {
				t.Operator = "="
			} else if t.Operator != ">" && t.Operator != "<" && t.Operator != "=" && t.Operator != "!=" && t.Operator != "like" {
				return fmt.Errorf("operator %s is not supported", t.Operator)
			}
		} else {
			// by intention sql string is not validated
			if t.Operator != "" {
				return http_error.NewHttpError(400, fmt.Sprintf("sql and operator are mutually exclusive (filter=%s)", t.Field))
			}
			if t.Value != nil {
				return http_error.NewHttpError(400, fmt.Sprintf("sql and value are mutually exclusive (filter=%s)", t.Field))
			}
		}

		query.Filters = append(query.Filters, t)
	}
	return nil
}

func readArray(parentValue *fastjson.Value) []any {
	list := make([]any, 0)
	for _, v := range parentValue.GetArray() {
		switch v.Type() {
		case fastjson.TypeFalse:
			list = append(list, false)
		case fastjson.TypeTrue:
			list = append(list, true)
		default:
			list = append(list, string(v.GetStringBytes()))
		}
	}
	return list
}