sq/drivers/xlsx/detect.go
Neil O'Toole edc933d897
#200: Feature/200 excel driver (#301)
* Switch to excelize driver
2023-08-16 09:09:50 -06:00

117 lines
2.9 KiB
Go

package xlsx
import (
"context"
"io"
"slices"
"github.com/neilotoole/sq/libsq/core/loz"
"github.com/neilotoole/sq/libsq/core/kind"
"github.com/xuri/excelize/v2"
"github.com/neilotoole/sq/libsq/core/errz"
"github.com/neilotoole/sq/libsq/core/lg"
"github.com/neilotoole/sq/libsq/core/lg/lgm"
"github.com/neilotoole/sq/libsq/source"
)
var _ source.DriverDetectFunc = DetectXLSX
// DetectXLSX implements source.DriverDetectFunc, returning
// TypeXLSX and a score of 1.0 if valid XLSX.
func DetectXLSX(ctx context.Context, openFn source.FileOpenFunc) (detected source.DriverType, score float32,
err error,
) {
log := lg.FromContext(ctx)
var r io.ReadCloser
r, err = openFn()
if err != nil {
return source.TypeNone, 0, errz.Err(err)
}
defer lg.WarnIfCloseError(log, lgm.CloseFileReader, r)
f, err := excelize.OpenReader(r)
if err != nil {
return source.TypeNone, 0, nil
}
defer lg.WarnIfCloseError(log, lgm.CloseFileReader, f)
return Type, 1.0, nil
}
func detectHeaderRow(ctx context.Context, sheet *xSheet) (hasHeader bool, err error) {
if len(sheet.sampleRows) < 2 {
// If zero records, obviously no header row.
// If one record... well, is there any way of determining if
// it's a header row or not? Probably best to treat it as a data row.
return false, nil
}
kinds1, _, err := detectSheetColumnKinds(sheet, 0)
if err != nil {
return false, err
}
kinds2, _, err := detectSheetColumnKinds(sheet, 1)
if err != nil {
return false, err
}
if len(kinds1) == len(kinds2) {
return !slices.Equal(kinds1, kinds2), nil
}
// The rows differ in length (ragged edges). Unfortunately this does
// happen in the real world, so we must deal with it.
lg.FromContext(ctx).Warn("Excel sheet has ragged edges", laSheet, sheet.name)
length := min(len(kinds1), len(kinds2))
kinds1 = kinds1[:length]
kinds2 = kinds2[:length]
return !slices.Equal(kinds1, kinds2), nil
}
// detectSheetColumnKinds calculates the lowest-common-denominator kind
// for the columns of sheet. It also returns munge funcs for ingesting
// each column's data (the munge func may be nil for any column).
func detectSheetColumnKinds(sheet *xSheet, rangeStart int) ([]kind.Kind, []kind.MungeFunc, error) {
rows := sheet.sampleRows
if rangeStart > len(rows) {
// Shouldn't happen
return nil, nil, errz.Errorf("excel: sheet {%s} is empty", sheet.name)
}
var detectors []*kind.Detector
for i := rangeStart; i < len(rows); i++ {
if loz.IsSliceZeroed(rows[i]) {
continue
}
for j := len(detectors); j < len(rows[i]); j++ {
detectors = append(detectors, kind.NewDetector())
}
for j := range rows[i] {
val := rows[i][j]
detectors[j].Sample(val)
}
}
kinds := make([]kind.Kind, len(detectors))
mungeFns := make([]kind.MungeFunc, len(detectors))
var err error
for j := range detectors {
if kinds[j], mungeFns[j], err = detectors[j].Detect(); err != nil {
return nil, nil, err
}
}
return kinds, mungeFns, nil
}