package gitparse

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/go-logr/logr"

	"github.com/trufflesecurity/trufflehog/v3/pkg/common"
	"github.com/trufflesecurity/trufflehog/v3/pkg/context"
)

const (
	// defaultDateFormat is the standard date format for git.
	defaultDateFormat = "Mon Jan 02 15:04:05 2006 -0700"

	// defaultMaxDiffSize is the maximum size for a diff. Larger diffs will be cut off.
	defaultMaxDiffSize = 2 * 1024 * 1024 * 1024 // 2GB

	// defaultMaxCommitSize is the maximum size for a commit. Larger commits will be cut off.
	defaultMaxCommitSize = 2 * 1024 * 1024 * 1024 // 2GB
)

// contentWriter defines a common interface for writing, reading, and managing diff content.
// It abstracts the underlying storage mechanism, allowing flexibility in how content is handled.
// This interface enables the use of different content storage strategies (e.g., in-memory buffer, file-based storage)
// based on performance needs or resource constraints, providing a unified way to interact with different content types.
type contentWriter interface { // Write appends data to the content storage.
	// Write appends data to the content storage.
	Write(ctx context.Context, data []byte) (int, error)
	// ReadCloser provides a reader for accessing stored content.
	ReadCloser() (io.ReadCloser, error)
	// CloseForWriting closes the content storage for writing.
	CloseForWriting() error
	// Len returns the current size of the content.
	Len() int
	// String returns the content as a string or an error if the content cannot be converted to a string.
	String() (string, error)
}

// state represents the current mode of buffer.
type state uint8

const (
	// writeOnly indicates the buffer is in write-only mode.
	writeOnly state = iota
	// readOnly indicates the buffer has been closed and is in read-only mode.
	readOnly
)

// buffer is a wrapper around bytes.Buffer, implementing the contentWriter interface.
// This allows bytes.Buffer to be used wherever a contentWriter is required, ensuring compatibility
// with the contentWriter interface while leveraging the existing implementation of bytes.Buffer.
type buffer struct {
	state state // current state of the buffer (writeOnly or readOnly)
	bytes.Buffer
}

func newBuffer() *buffer { return &buffer{state: writeOnly} }

// Write delegates the writing operation to the underlying bytes.Buffer, ignoring the context.
// The context is included to satisfy the contentWriter interface, allowing for future extensions
// where context handling might be necessary (e.g., for timeouts or cancellation).
func (b *buffer) Write(_ context.Context, data []byte) (int, error) {
	if b.state == readOnly {
		return 0, fmt.Errorf("buffer is in read-only mode")
	}
	return b.Buffer.Write(data)
}

// ReadCloser provides a read-closer for the buffer's content.
// It wraps the buffer's content in a NopCloser to provide a ReadCloser without additional closing behavior,
// as closing a bytes.Buffer is a no-op.
func (b *buffer) ReadCloser() (io.ReadCloser, error) {
	if b.state == writeOnly {
		return nil, fmt.Errorf("buffer is in write-only mode")
	}
	return io.NopCloser(bytes.NewReader(b.Bytes())), nil
}

// CloseForWriting is a no-op for buffer, as there is no resource cleanup needed for bytes.Buffer.
func (b *buffer) CloseForWriting() error {
	b.state = readOnly
	return nil
}

// String returns the buffer's content as a string.
func (b *buffer) String() (string, error) { return b.Buffer.String(), nil }

// Diff contains the information about a file diff in a commit.
// It abstracts the underlying content representation, allowing for flexible handling of diff content.
// The use of contentWriter enables the management of diff data either in memory or on disk,
// based on its size, optimizing resource usage and performance.
type Diff struct {
	PathB         string
	LineStart     int
	contentWriter contentWriter
	IsBinary      bool
}

type diffOption func(*Diff)

// withPathB sets the PathB option.
func withPathB(pathB string) diffOption { return func(d *Diff) { d.PathB = pathB } }

// NewDiff creates a new Diff with a threshold.
func NewDiff(opts ...diffOption) *Diff {
	diff := new(Diff)
	diff.contentWriter = newBuffer()
	for _, opt := range opts {
		opt(diff)
	}

	return diff
}

// Len returns the length of the storage.
func (d *Diff) Len() int { return d.contentWriter.Len() }

// ReadCloser returns a ReadCloser for the contentWriter.
func (d *Diff) ReadCloser() (io.ReadCloser, error) { return d.contentWriter.ReadCloser() }

// write delegates to the contentWriter.
func (d *Diff) write(ctx context.Context, p []byte) error {
	_, err := d.contentWriter.Write(ctx, p)
	return err
}

// finalize ensures proper closure of resources associated with the Diff.
// handle the final flush in the finalize method, in case there's data remaining in the buffer.
// This method should be called to release resources, especially when writing to a file.
func (d *Diff) finalize() error { return d.contentWriter.CloseForWriting() }

// Commit contains commit header info and diffs.
type Commit struct {
	Hash    string
	Author  string
	Date    time.Time
	Message strings.Builder
	Diffs   []Diff
	Size    int // in bytes
}

// Equal compares the content of two Commits to determine if they are the same.
func (c1 *Commit) Equal(ctx context.Context, c2 *Commit) bool {
	switch {
	case c1.Hash != c2.Hash:
		return false
	case c1.Author != c2.Author:
		return false
	case !c1.Date.Equal(c2.Date):
		return false
	case c1.Message.String() != c2.Message.String():
		return false
	case len(c1.Diffs) != len(c2.Diffs):
		return false
	}

	// isEqualString handles the error-prone String() method calls and compares the results.
	isEqualContentString := func(s1, s2 contentWriter) (bool, error) {
		str1, err := s1.String()
		if err != nil {
			return false, err
		}
		str2, err := s2.String()
		if err != nil {
			return false, err
		}
		return str1 == str2, nil
	}

	for i := range c1.Diffs {
		d1 := c1.Diffs[i]
		d2 := c2.Diffs[i]
		switch {
		case d1.PathB != d2.PathB:
			return false
		case d1.LineStart != d2.LineStart:
			return false
		case d1.IsBinary != d2.IsBinary:
			return false
		default:
			equal, err := isEqualContentString(d1.contentWriter, d2.contentWriter)
			if err != nil || !equal {
				ctx.Logger().Error(err, "failed to compare diff content")
				return false
			}
		}
	}
	return true
}

// Parser sets values used in GitParse.
type Parser struct {
	maxDiffSize   int
	maxCommitSize int
	dateFormat    string
	contentWriter contentWriter
}

type ParseState int

const (
	Initial ParseState = iota
	CommitLine
	MergeLine
	AuthorLine
	DateLine
	MessageStartLine
	MessageLine
	MessageEndLine
	DiffLine
	ModeLine
	IndexLine
	FromFileLine
	ToFileLine
	BinaryFileLine
	HunkLineNumberLine
	HunkContentLine
	ParseFailure
)

func (state ParseState) String() string {
	return [...]string{
		"Initial",
		"CommitLine",
		"MergeLine",
		"AuthorLine",
		"DateLine",
		"MessageStartLine",
		"MessageLine",
		"MessageEndLine",
		"DiffLine",
		"ModeLine",
		"IndexLine",
		"FromFileLine",
		"ToFileLine",
		"BinaryFileLine",
		"HunkLineNumberLine",
		"HunkContentLine",
		"ParseFailure",
	}[state]
}

// WithContentWriter sets the ContentWriter for the Parser.
func WithContentWriter(writer contentWriter) Option {
	return func(parser *Parser) {
		parser.contentWriter = writer
	}
}

// WithMaxDiffSize sets maxDiffSize option. Diffs larger than maxDiffSize will
// be truncated.
func WithMaxDiffSize(maxDiffSize int) Option {
	return func(parser *Parser) {
		parser.maxDiffSize = maxDiffSize
	}
}

// WithMaxCommitSize sets maxCommitSize option. Commits larger than maxCommitSize
// will be put in the commit channel and additional diffs will be added to a
// new commit.
func WithMaxCommitSize(maxCommitSize int) Option {
	return func(parser *Parser) {
		parser.maxCommitSize = maxCommitSize
	}
}

// Option is used for adding options to Config.
type Option func(*Parser)

// NewParser creates a GitParse config from options and sets defaults.
func NewParser(options ...Option) *Parser {
	parser := &Parser{
		dateFormat:    defaultDateFormat,
		maxDiffSize:   defaultMaxDiffSize,
		maxCommitSize: defaultMaxCommitSize,
		contentWriter: newBuffer(),
	}
	for _, option := range options {
		option(parser)
	}
	return parser
}

// RepoPath parses the output of the `git log` command for the `source` path.
func (c *Parser) RepoPath(ctx context.Context, source string, head string, abbreviatedLog bool, excludedGlobs []string, isBare bool) (chan Commit, error) {
	tmpFile, err := ioutil.TempFile("", "example")
	if err != nil {
		return nil, err
	}

	args := []string{"-C", source, "log", "-p", "--full-history", "--date=format:%a %b %d %H:%M:%S %Y %z"}
	if abbreviatedLog {
		args = append(args, "--diff-filter=AM")
	}
	if head != "" {
		args = append(args, head)
	} else {
		args = append(args, "--all")
	}
	for _, glob := range excludedGlobs {
		args = append(args, "--", ".", fmt.Sprintf(":(exclude)%s", glob))
	}

	cmd := exec.Command("git", args...)

	cmd.Stdout = tmpFile

	absPath, err := filepath.Abs(source)
	if err == nil {
		if !isBare {
			cmd.Env = append(cmd.Env, "GIT_DIR="+filepath.Join(absPath, ".git"))
		} else {
			cmd.Env = append(cmd.Env,
				"GIT_DIR="+absPath,
			)
			// We need those variables to handle incoming commits
			// while using trufflehog in pre-receive hooks
			if dir := os.Getenv("GIT_OBJECT_DIRECTORY"); dir != "" {
				cmd.Env = append(cmd.Env, "GIT_OBJECT_DIRECTORY="+dir)
			}
			if dir := os.Getenv("GIT_ALTERNATE_OBJECT_DIRECTORIES"); dir != "" {
				cmd.Env = append(cmd.Env, "GIT_ALTERNATE_OBJECT_DIRECTORIES="+dir)
			}
		}
	}

	return c.executeCommand(ctx, cmd, false)
}

// Staged parses the output of the `git diff` command for the `source` path.
func (c *Parser) Staged(ctx context.Context, source string) (chan Commit, error) {
	// Provide the --cached flag to diff to get the diff of the staged changes.
	args := []string{"-C", source, "diff", "-p", "--cached", "--full-history", "--diff-filter=AM", "--date=format:%a %b %d %H:%M:%S %Y %z"}

	cmd := exec.Command("git", args...)

	absPath, err := filepath.Abs(source)
	if err == nil {
		cmd.Env = append(cmd.Env, fmt.Sprintf("GIT_DIR=%s", filepath.Join(absPath, ".git")))
	}

	return c.executeCommand(ctx, cmd, true)
}

// executeCommand runs an exec.Cmd, reads stdout and stderr, and waits for the Cmd to complete.
func (c *Parser) executeCommand(ctx context.Context, cmd *exec.Cmd, isStaged bool) (chan Commit, error) {
	commitChan := make(chan Commit, 64)

	err := cmd.Run()
	if err != nil {
		return commitChan, err
	}

	go func() {
		tmpFile := cmd.Stdout.(*os.File)
		defer os.Remove(tmpFile.Name())
		tmpFile.Seek(0, 0)
		c.FromReader(ctx, tmpFile, commitChan, isStaged)
		if err := cmd.Wait(); err != nil {
			ctx.Logger().V(2).Info("Error waiting for git command to complete.", "error", err)
		}
	}()

	return commitChan, nil
}

func (c *Parser) FromReader(ctx context.Context, stdOut io.Reader, commitChan chan Commit, isStaged bool) {
	outReader := bufio.NewReader(stdOut)
	var (
		currentCommit *Commit

		totalLogSize int
	)
	var latestState = Initial
	currentDiff := NewDiff()

	defer common.RecoverWithExit(ctx)
	defer close(commitChan)
	for {
		if common.IsDone(ctx) {
			break
		}

		line, err := outReader.ReadBytes([]byte("\n")[0])
		if err != nil && len(line) == 0 {
			break
		}

		switch {
		case isCommitLine(isStaged, latestState, line):
			latestState = CommitLine

			// If there is a currentDiff, add it to currentCommit.
			if currentDiff.Len() > 0 || currentDiff.IsBinary {
				// TODO: Consider modifying the diffs field in the Commit struct to be a []*Diff.
				// Otherwise, we end up with this temporal coupling where we have to finalize the diff
				// before we can add it to the commit. I found this out the hard way when I tried to
				// test this.
				if err := currentDiff.finalize(); err != nil {
					ctx.Logger().Error(
						err,
						"failed to finalize diff",
						"commit", currentCommit.Hash,
						"diff", currentDiff.PathB,
						"size", currentDiff.Len(),
						"latest_state", latestState.String(),
					)
				}
				currentCommit.Diffs = append(currentCommit.Diffs, *currentDiff)
				currentCommit.Size += currentDiff.Len()
			}
			// If there is a currentCommit, send it to the channel.
			if currentCommit != nil {
				commitChan <- *currentCommit
				totalLogSize += currentCommit.Size
			}
			// Create a new currentDiff and currentCommit
			currentDiff = NewDiff()
			currentCommit = &Commit{Message: strings.Builder{}}
			// Check that the commit line contains a hash and set it.
			if len(line) >= 47 {
				currentCommit.Hash = string(line[7:47])
			}
		case isMergeLine(isStaged, latestState, line):
			latestState = MergeLine
		case isAuthorLine(isStaged, latestState, line):
			latestState = AuthorLine

			currentCommit.Author = strings.TrimRight(string(line[8:]), "\n")
		case isDateLine(isStaged, latestState, line):
			latestState = DateLine

			date, err := time.Parse(c.dateFormat, strings.TrimSpace(string(line[6:])))
			if err != nil {
				ctx.Logger().V(2).Info("Could not parse date from git stream.", "error", err)
			}
			currentCommit.Date = date
		case isMessageStartLine(isStaged, latestState, line):
			latestState = MessageStartLine
			// NoOp
		case isMessageLine(isStaged, latestState, line):
			latestState = MessageLine

			currentCommit.Message.Write(line[4:]) // Messages are indented with 4 spaces.
		case isMessageEndLine(isStaged, latestState, line):
			latestState = MessageEndLine
			// NoOp
		case isDiffLine(isStaged, latestState, line):
			latestState = DiffLine

			// This should never be nil, but check in case the stdin stream is messed up.
			if currentCommit == nil {
				currentCommit = &Commit{}
			}
			if currentDiff.Len() > 0 || currentDiff.IsBinary {
				if err := currentDiff.finalize(); err != nil {
					ctx.Logger().Error(err,
						"failed to finalize diff",
						"commit", currentCommit.Hash,
						"diff", currentDiff.PathB,
						"size", currentDiff.Len(),
						"latest_state", latestState.String(),
					)
				}
				currentCommit.Diffs = append(currentCommit.Diffs, *currentDiff)
				// If the currentDiff is over 1GB, drop it into the channel so it isn't held in memory waiting for more commits.
				totalSize := 0
				for _, diff := range currentCommit.Diffs {
					totalSize += diff.Len()
				}
				if totalSize > c.maxCommitSize {
					oldCommit := currentCommit
					commitChan <- *currentCommit
					totalLogSize += currentCommit.Size
					currentCommit = &Commit{
						Hash:    currentCommit.Hash,
						Author:  currentCommit.Author,
						Date:    currentCommit.Date,
						Message: strings.Builder{},
						Diffs:   []Diff{},
					}
					// Message needs to be recreated here otherwise writing to it again will result in a panic.
					currentCommit.Message.WriteString(oldCommit.Message.String())
				}
			}
			currentDiff = NewDiff()
		case isModeLine(isStaged, latestState, line):
			latestState = ModeLine
			// NoOp
		case isIndexLine(isStaged, latestState, line):
			latestState = IndexLine
			// NoOp
		case isBinaryLine(isStaged, latestState, line):
			latestState = BinaryFileLine

			currentDiff.PathB = pathFromBinaryLine(line)

			// Don't do anything if the file is deleted. (pathA has file path, pathB is /dev/null)
			if currentDiff.PathB != "" {
				currentDiff.IsBinary = true
			}
		case isFromFileLine(isStaged, latestState, line):
			latestState = FromFileLine
			// NoOp
		case isToFileLine(isStaged, latestState, line):
			latestState = ToFileLine

			// TODO: Is this fix still required?
			currentDiff.PathB = strings.TrimRight(strings.TrimRight(string(line[6:]), "\n"), "\t") // Trim the newline and tab characters. https://github.com/trufflesecurity/trufflehog/issues/1060
		case isHunkLineNumberLine(isStaged, latestState, line):
			latestState = HunkLineNumberLine

			if currentDiff.Len() > 0 || currentDiff.IsBinary {
				if err := currentDiff.finalize(); err != nil {
					ctx.Logger().Error(
						err,
						"failed to finalize diff",
						"commit", currentCommit.Hash,
						"diff", currentDiff.PathB,
						"size", currentDiff.Len(),
						"latest_state", latestState.String(),
					)
				}
				currentCommit.Diffs = append(currentCommit.Diffs, *currentDiff)
			}
			currentDiff = NewDiff(withPathB(currentDiff.PathB))

			words := bytes.Split(line, []byte(" "))
			if len(words) >= 3 {
				startSlice := bytes.Split(words[2], []byte(","))
				lineStart, err := strconv.Atoi(string(startSlice[0]))
				if err == nil {
					currentDiff.LineStart = lineStart
				}
			}
		case isHunkContextLine(isStaged, latestState, line):
			if latestState != HunkContentLine {
				latestState = HunkContentLine
			}
			// TODO: Why do we care about this? It creates empty lines in the diff. If there are no plusLines, it's just newlines.
			if err := currentDiff.write(ctx, []byte("\n")); err != nil {
				ctx.Logger().Error(err, "failed to write to diff")
			}
		case isHunkPlusLine(isStaged, latestState, line):
			if latestState != HunkContentLine {
				latestState = HunkContentLine
			}

			if err := currentDiff.write(ctx, line[1:]); err != nil {
				ctx.Logger().Error(err, "failed to write to diff")
			}
			// NoOp. We only care about additions.
		case isHunkMinusLine(isStaged, latestState, line),
			isHunkNewlineWarningLine(isStaged, latestState, line),
			isHunkEmptyLine(isStaged, latestState, line):
			if latestState != HunkContentLine {
				latestState = HunkContentLine
			}
			// NoOp
		case isCommitSeparatorLine(isStaged, latestState, line):
			// NoOp
		default:
			// Skip ahead until we find the next diff or commit.
			if latestState == ParseFailure {
				continue
			}

			// Here be dragons...
			// Build an informative error message.
			err := fmt.Errorf(`invalid line "%s" after state "%s"`, line, latestState)
			var logger logr.Logger
			if currentCommit != nil && currentCommit.Hash != "" {
				logger = ctx.Logger().WithValues("commit", currentCommit.Hash)
			} else {
				logger = ctx.Logger()
			}
			logger.Error(err, "failed to parse Git input. Recovering at the latest commit or diff...")

			latestState = ParseFailure
		}

		if currentDiff.Len() > c.maxDiffSize {
			ctx.Logger().V(2).Info(fmt.Sprintf(
				"Diff for %s exceeded MaxDiffSize(%d)", currentDiff.PathB, c.maxDiffSize,
			))
			break
		}
	}
	cleanupParse(ctx, currentCommit, currentDiff, commitChan, &totalLogSize)

	ctx.Logger().V(2).Info("finished parsing git log.", "total_log_size", totalLogSize)
}

func isMergeLine(isStaged bool, latestState ParseState, line []byte) bool {
	if isStaged || latestState != CommitLine {
		return false
	}
	if len(line) > 6 && bytes.Equal(line[:6], []byte("Merge:")) {
		return true
	}
	return false
}

// commit 7a95bbf0199e280a0e42dbb1d1a3f56cdd0f6e05
func isCommitLine(isStaged bool, latestState ParseState, line []byte) bool {
	if isStaged || !(latestState == Initial ||
		latestState == MessageStartLine ||
		latestState == MessageEndLine ||
		latestState == ModeLine ||
		latestState == IndexLine ||
		latestState == BinaryFileLine ||
		latestState == ToFileLine ||
		latestState == HunkContentLine ||
		latestState == ParseFailure) {
		return false
	}

	if len(line) > 7 && bytes.Equal(line[:7], []byte("commit ")) {
		return true
	}
	return false
}

// Author: Bill Rich <bill.rich@trufflesec.com>
func isAuthorLine(isStaged bool, latestState ParseState, line []byte) bool {
	if isStaged || !(latestState == CommitLine || latestState == MergeLine) {
		return false
	}
	if len(line) > 8 && bytes.Equal(line[:7], []byte("Author:")) {
		return true
	}
	return false
}

// Date:   Tue Aug 10 15:20:40 2021 +0100
func isDateLine(isStaged bool, latestState ParseState, line []byte) bool {
	if isStaged || latestState != AuthorLine {
		return false
	}
	if len(line) > 7 && bytes.Equal(line[:5], []byte("Date:")) {
		return true
	}
	return false
}

// Line directly after Date with only a newline.
func isMessageStartLine(isStaged bool, latestState ParseState, line []byte) bool {
	if isStaged || latestState != DateLine {
		return false
	}
	// TODO: Improve the implementation of this and isMessageEndLine
	if len(strings.TrimRight(string(line[:]), "\r\n")) == 0 {
		return true
	}
	return false
}

// Line that starts with 4 spaces
func isMessageLine(isStaged bool, latestState ParseState, line []byte) bool {
	if isStaged || !(latestState == MessageStartLine || latestState == MessageLine) {
		return false
	}
	if len(line) > 4 && bytes.Equal(line[:4], []byte("    ")) {
		return true
	}
	return false
}

// Line directly after MessageLine with only a newline.
func isMessageEndLine(isStaged bool, latestState ParseState, line []byte) bool {
	if isStaged || latestState != MessageLine {
		return false
	}
	if len(strings.TrimRight(string(line[:]), "\r\n")) == 0 {
		return true
	}
	return false
}

// diff --git a/internal/addrs/move_endpoint_module.go b/internal/addrs/move_endpoint_module.go
func isDiffLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == MessageStartLine || // Empty commit messages can go from MessageStart->Diff
		latestState == MessageEndLine ||
		latestState == BinaryFileLine ||
		latestState == IndexLine ||
		latestState == HunkContentLine ||
		latestState == ParseFailure) {
		if latestState == Initial && !isStaged {
			return false
		}
	}
	if len(line) > 11 && bytes.Equal(line[:11], []byte("diff --git ")) {
		return true
	}
	return false
}

// old mode 100644
// new mode 100755
// new file mode 100644
// similarity index 100%
// rename from old.txt
// rename to new.txt
// deleted file mode 100644
func isModeLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == DiffLine || latestState == ModeLine) {
		return false
	}
	// This could probably be better written.
	if (len(line) > 17 && bytes.Equal(line[:17], []byte("deleted file mode"))) ||
		(len(line) > 16 && bytes.Equal(line[:16], []byte("similarity index"))) ||
		(len(line) > 13 && bytes.Equal(line[:13], []byte("new file mode"))) ||
		(len(line) > 11 && bytes.Equal(line[:11], []byte("rename from"))) ||
		(len(line) > 9 && bytes.Equal(line[:9], []byte("rename to"))) ||
		(len(line) > 8 && bytes.Equal(line[:8], []byte("old mode"))) ||
		(len(line) > 8 && bytes.Equal(line[:8], []byte("new mode"))) {
		return true
	}
	return false
}

// index 1ed6fbee1..aea1e643a 100644
// index 00000000..e69de29b
func isIndexLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == DiffLine || latestState == ModeLine) {
		return false
	}
	if len(line) > 6 && bytes.Equal(line[:6], []byte("index ")) {
		return true
	}
	return false
}

// Binary files /dev/null and b/plugin.sig differ
func isBinaryLine(isStaged bool, latestState ParseState, line []byte) bool {
	if latestState != IndexLine {
		return false
	}
	if len(line) > 7 && bytes.Equal(line[:6], []byte("Binary")) {
		return true
	}
	return false
}

// Get the b/ file path. Ignoring the edge case of files having `and /b` in the name for simplicity.
func pathFromBinaryLine(line []byte) string {
	logger := context.Background().Logger()
	sbytes := bytes.Split(line, []byte(" and b/"))
	if len(sbytes) != 2 {
		logger.V(2).Info("Expected binary line to be in 'Binary files a/fileA and b/fileB differ' format.", "got", line)
		return ""
	}
	bRaw := sbytes[1]
	return string(bRaw[:len(bRaw)-8]) // drop the "b/" and " differ\n"
}

// --- a/internal/addrs/move_endpoint_module.go
// --- /dev/null
func isFromFileLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == IndexLine || latestState == ModeLine) {
		return false
	}
	if len(line) >= 6 && bytes.Equal(line[:4], []byte("--- ")) {
		return true
	}
	return false
}

// +++ b/internal/addrs/move_endpoint_module.go
func isToFileLine(isStaged bool, latestState ParseState, line []byte) bool {
	if latestState != FromFileLine {
		return false
	}
	if len(line) >= 6 && bytes.Equal(line[:4], []byte("+++ ")) {
		return true
	}
	return false
}

// @@ -298 +298 @@ func maxRetryErrorHandler(resp *http.Response, err error, numTries int)
func isHunkLineNumberLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == ToFileLine || latestState == HunkContentLine) {
		return false
	}
	if len(line) >= 8 && bytes.Equal(line[:2], []byte("@@")) {
		return true
	}
	return false
}

// fmt.Println("ok")
// (There's a space before `fmt` that gets removed by the formatter.)
func isHunkContextLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == HunkLineNumberLine || latestState == HunkContentLine) {
		return false
	}
	if len(line) >= 1 && bytes.Equal(line[:1], []byte(" ")) {
		return true
	}
	return false
}

// +fmt.Println("ok")
func isHunkPlusLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == HunkLineNumberLine || latestState == HunkContentLine) {
		return false
	}
	if len(line) >= 1 && bytes.Equal(line[:1], []byte("+")) {
		return true
	}
	return false
}

// -fmt.Println("ok")
func isHunkMinusLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == HunkLineNumberLine || latestState == HunkContentLine) {
		return false
	}
	if len(line) >= 1 && bytes.Equal(line[:1], []byte("-")) {
		return true
	}
	return false
}

// \ No newline at end of file
func isHunkNewlineWarningLine(isStaged bool, latestState ParseState, line []byte) bool {
	if latestState != HunkContentLine {
		return false
	}
	if len(line) >= 27 && bytes.Equal(line[:27], []byte("\\ No newline at end of file")) {
		return true
	}
	return false
}

// Newline after hunk, or an empty line, e.g.
// +}
//
// commit 00920984e3435057f09cee5468850f7546dfa637 (tag: v3.42.0)
func isHunkEmptyLine(isStaged bool, latestState ParseState, line []byte) bool {
	if !(latestState == HunkLineNumberLine || latestState == HunkContentLine) {
		return false
	}
	// TODO: Can this also be `\n\r`?
	if len(line) == 1 && bytes.Equal(line[:1], []byte("\n")) {
		return true
	}
	return false
}

func isCommitSeparatorLine(isStaged bool, latestState ParseState, line []byte) bool {
	if (latestState == ModeLine || latestState == IndexLine || latestState == BinaryFileLine || latestState == ToFileLine) &&
		len(line) == 1 && bytes.Equal(line[:1], []byte("\n")) {
		return true
	}
	return false
}

func cleanupParse(ctx context.Context, currentCommit *Commit, currentDiff *Diff, commitChan chan Commit, totalLogSize *int) {
	if err := currentDiff.finalize(); err != nil {
		ctx.Logger().Error(err, "failed to finalize diff")
		return
	}
	// Ignore empty or binary diffs (this condition may be redundant).
	if currentDiff != nil && (currentDiff.Len() > 0 || currentDiff.IsBinary) {
		currentCommit.Diffs = append(currentCommit.Diffs, *currentDiff)
	}
	if currentCommit != nil {
		commitChan <- *currentCommit
		if totalLogSize != nil {
			*totalLogSize += currentCommit.Size
		}
	}
}