refactor: Decompose query func

pkg/recovery/query.go

@@ -2,7 +2,17 @@ package recovery
 
 import (
 	"archive/tar"
+	"bufio"
+	"io"
+	"io/ioutil"
+	"math"
 
+	"github.com/pojntfx/stfs/internal/controllers"
+	"github.com/pojntfx/stfs/internal/counters"
+	"github.com/pojntfx/stfs/internal/encryption"
+	"github.com/pojntfx/stfs/internal/formatting"
+	"github.com/pojntfx/stfs/internal/signature"
+	"github.com/pojntfx/stfs/internal/tape"
 	"github.com/pojntfx/stfs/pkg/config"
 )
 
@@ -15,5 +25,199 @@ func Query(
 	record int,
 	block int,
 ) ([]*tar.Header, error) {
-	return nil, nil
+	f, isRegular, err := tape.OpenTapeReadOnly(state.Drive)
+	if err != nil {
+		return []*tar.Header{}, err
+	}
+	defer f.Close()
+
+	headers := []*tar.Header{}
+
+	if isRegular {
+		// Seek to record and block
+		if _, err := f.Seek(int64((recordSize*controllers.BlockSize*record)+block*controllers.BlockSize), 0); err != nil {
+			return []*tar.Header{}, err
+		}
+
+		tr := tar.NewReader(f)
+
+		record := int64(record)
+		block := int64(block)
+
+		for {
+			hdr, err := tr.Next()
+			if err != nil {
+				for {
+					curr, err := f.Seek(0, io.SeekCurrent)
+					if err != nil {
+						return []*tar.Header{}, err
+					}
+
+					nextTotalBlocks := math.Ceil(float64((curr)) / float64(controllers.BlockSize))
+					record = int64(nextTotalBlocks) / int64(recordSize)
+					block = int64(nextTotalBlocks) - (record * int64(recordSize))
+
+					if block < 0 {
+						record--
+						block = int64(recordSize) - 1
+					} else if block >= int64(recordSize) {
+						record++
+						block = 0
+					}
+
+					// Seek to record and block
+					if _, err := f.Seek(int64((recordSize*controllers.BlockSize*int(record))+int(block)*controllers.BlockSize), io.SeekStart); err != nil {
+						return []*tar.Header{}, err
+					}
+
+					tr = tar.NewReader(f)
+
+					hdr, err = tr.Next()
+					if err != nil {
+						if err == io.EOF {
+							// EOF
+
+							break
+						}
+
+						continue
+					}
+
+					break
+				}
+			}
+
+			if hdr == nil {
+				// EOF
+
+				break
+			}
+
+			if err := encryption.DecryptHeader(hdr, pipes.Encryption, crypto.Identity); err != nil {
+				return []*tar.Header{}, err
+			}
+
+			if err := signature.VerifyHeader(hdr, isRegular, pipes.Signature, crypto.Recipient); err != nil {
+				return []*tar.Header{}, err
+			}
+
+			if record == 0 && block == 0 {
+				if err := formatting.PrintCSV(formatting.TARHeaderCSV); err != nil {
+					return []*tar.Header{}, err
+				}
+			}
+
+			if err := formatting.PrintCSV(formatting.GetTARHeaderAsCSV(record, block, hdr)); err != nil {
+				return []*tar.Header{}, err
+			}
+
+			headers = append(headers, hdr)
+
+			curr, err := f.Seek(0, io.SeekCurrent)
+			if err != nil {
+				return []*tar.Header{}, err
+			}
+
+			if _, err := io.Copy(ioutil.Discard, tr); err != nil {
+				return []*tar.Header{}, err
+			}
+
+			currAndSize, err := f.Seek(0, io.SeekCurrent)
+			if err != nil {
+				return []*tar.Header{}, err
+			}
+
+			nextTotalBlocks := math.Ceil(float64(curr+(currAndSize-curr)) / float64(controllers.BlockSize))
+			record = int64(nextTotalBlocks) / int64(recordSize)
+			block = int64(nextTotalBlocks) - (record * int64(recordSize))
+
+			if block > int64(recordSize) {
+				record++
+				block = 0
+			}
+		}
+	} else {
+		// Seek to record
+		if err := controllers.SeekToRecordOnTape(f, int32(record)); err != nil {
+			return []*tar.Header{}, err
+		}
+
+		// Seek to block
+		br := bufio.NewReaderSize(f, controllers.BlockSize*recordSize)
+		if _, err := br.Read(make([]byte, block*controllers.BlockSize)); err != nil {
+			return []*tar.Header{}, err
+		}
+
+		record := int64(record)
+		block := int64(block)
+
+		curr := int64((recordSize * controllers.BlockSize * int(record)) + (int(block) * controllers.BlockSize))
+		counter := &counters.CounterReader{Reader: br, BytesRead: int(curr)}
+
+		tr := tar.NewReader(counter)
+		for {
+			hdr, err := tr.Next()
+			if err != nil {
+				if err == io.EOF {
+					if err := controllers.GoToNextFileOnTape(f); err != nil {
+						// EOD
+
+						break
+					}
+
+					record, err = controllers.GetCurrentRecordFromTape(f)
+					if err != nil {
+						return []*tar.Header{}, err
+					}
+					block = 0
+
+					br = bufio.NewReaderSize(f, controllers.BlockSize*recordSize)
+					curr := int64(int64(recordSize) * controllers.BlockSize * record)
+					counter := &counters.CounterReader{Reader: br, BytesRead: int(curr)}
+					tr = tar.NewReader(counter)
+
+					continue
+				} else {
+					return []*tar.Header{}, err
+				}
+			}
+
+			if err := encryption.DecryptHeader(hdr, pipes.Encryption, crypto.Identity); err != nil {
+				return []*tar.Header{}, err
+			}
+
+			if err := signature.VerifyHeader(hdr, isRegular, pipes.Signature, crypto.Recipient); err != nil {
+				return []*tar.Header{}, err
+			}
+
+			if record == 0 && block == 0 {
+				if err := formatting.PrintCSV(formatting.TARHeaderCSV); err != nil {
+					return []*tar.Header{}, err
+				}
+			}
+
+			if err := formatting.PrintCSV(formatting.GetTARHeaderAsCSV(record, block, hdr)); err != nil {
+				return []*tar.Header{}, err
+			}
+
+			headers = append(headers, hdr)
+
+			if _, err := io.Copy(ioutil.Discard, tr); err != nil {
+				return []*tar.Header{}, err
+			}
+
+			currAndSize := int64(counter.BytesRead)
+
+			nextTotalBlocks := math.Ceil(float64(curr+(currAndSize-curr)) / float64(controllers.BlockSize))
+			record = int64(nextTotalBlocks) / int64(recordSize)
+			block = int64(nextTotalBlocks) - (record * int64(recordSize))
+
+			if block > int64(recordSize) {
+				record++
+				block = 0
+			}
+		}
+	}
+
+	return headers, nil
 }