package logstorage

import (
	"fmt"
	"math"
	"slices"
	"strconv"
	"unsafe"
)

type statsSum struct {
	fields       []string
	containsStar bool
	resultName   string
}

func (ss *statsSum) String() string {
	return "sum(" + fieldNamesString(ss.fields) + ") as " + quoteTokenIfNeeded(ss.resultName)
}

func (ss *statsSum) neededFields() []string {
	return ss.fields
}

func (ss *statsSum) newStatsProcessor() (statsProcessor, int) {
	ssp := &statsSumProcessor{
		ss: ss,
	}
	return ssp, int(unsafe.Sizeof(*ssp))
}

type statsSumProcessor struct {
	ss *statsSum

	sum float64
}

func (ssp *statsSumProcessor) updateStatsForAllRows(br *blockResult) int {
	if ssp.ss.containsStar {
		// Sum all the columns
		for _, c := range br.getColumns() {
			ssp.sum += c.sumValues(br)
		}
		return 0
	}

	// Sum the requested columns
	for _, field := range ssp.ss.fields {
		c := br.getColumnByName(field)
		ssp.sum += c.sumValues(br)
	}
	return 0
}

func (ssp *statsSumProcessor) updateStatsForRow(br *blockResult, rowIdx int) int {
	if ssp.ss.containsStar {
		// Sum all the fields for the given row
		for _, c := range br.getColumns() {
			f := c.getFloatValueAtRow(rowIdx)
			if !math.IsNaN(f) {
				ssp.sum += f
			}
		}
		return 0
	}

	// Sum only the given fields for the given row
	for _, field := range ssp.ss.fields {
		c := br.getColumnByName(field)
		f := c.getFloatValueAtRow(rowIdx)
		if !math.IsNaN(f) {
			ssp.sum += f
		}
	}
	return 0
}

func (ssp *statsSumProcessor) mergeState(sfp statsProcessor) {
	src := sfp.(*statsSumProcessor)
	ssp.sum += src.sum
}

func (ssp *statsSumProcessor) finalizeStats() (string, string) {
	value := strconv.FormatFloat(ssp.sum, 'f', -1, 64)
	return ssp.ss.resultName, value
}

func parseStatsSum(lex *lexer) (*statsSum, error) {
	lex.nextToken()
	fields, err := parseFieldNamesInParens(lex)
	if err != nil {
		return nil, fmt.Errorf("cannot parse 'sum' args: %w", err)
	}
	if len(fields) == 0 {
		return nil, fmt.Errorf("'sum' must contain at least one arg")
	}
	resultName, err := parseResultName(lex)
	if err != nil {
		return nil, fmt.Errorf("cannot parse result name: %w", err)
	}
	ss := &statsSum{
		fields:       fields,
		containsStar: slices.Contains(fields, "*"),
		resultName:   resultName,
	}
	return ss, nil
}