package storage

import (
	"fmt"

	bin "gordenko.dev/dima/bin/little"
	"gordenko.dev/dima/qb"
	"gordenko.dev/dima/qb/enc"
	"gordenko.dev/dima/qb/util"
)

func CreateTimestampDecompressor(page []byte) (qb.TimestampDecompressor, error) {
	size, _ := bin.GetUint16(page[timestampsSizeIdx:])
	if size > DataPageFooterSize {
		return nil, fmt.Errorf("bug: invalid timestamps size %d", size)
	}
	pos := DataPagePayloadSize - int(size)
	d := enc.NewTimeDeltaDecompressor()
	d.RestoreFromEnd(page[pos:DataPagePayloadSize])
	return d, nil
}

func CreateValueDecompressor(page []byte, metricType qb.MetricType, fracDigits byte) (qb.ValueDecompressor, error) {
	size, _ := bin.GetUint16(page[valuesSizeIdx:])
	if size > DataPageFooterSize {
		return nil, fmt.Errorf("bug: invalid timestamps size %d", size)
	}
	d := enc.NewValueDeltaDecompressor(metricType, fracDigits)
	d.RestoreFromEnd(page[:size])
	return d, nil
}

func VerifyDataPageCRC32(data []byte) error {
	var (
		calculatedCRC = util.CalculateCRC32(data[:dataCRC32Idx])
		writtenCRC, _ = bin.GetUint32(data[dataCRC32Idx:])
	)
	if calculatedCRC != writtenCRC {
		return fmt.Errorf("calculated CRC32 %d are not equal written CRC32 %d",
			calculatedCRC, writtenCRC)
	}
	return nil
}

func VerifyIndexPageCRC32(data []byte) error {
	var (
		calculatedCRC = util.CalculateCRC32(data[:indexCRC32Idx])
		writtenCRC, _ = bin.GetUint32(data[indexCRC32Idx:])
	)
	if calculatedCRC != writtenCRC {
		return fmt.Errorf("calculated CRC32 %d are not equal written CRC32 %d",
			calculatedCRC, writtenCRC)
	}
	return nil
}