feat: retrieve a list of diffs for all files that have outstanding changes

diff.go

@@ -0,0 +1,257 @@
+package git
+
+import (
+	"bufio"
+	"strconv"
+	"strings"
+
+	"github.com/purpleclay/chomp"
+	"github.com/purpleclay/gitz/scan"
+)
+
+const (
+	// git diff header delimiter > @@ ... @@
+	hdrDelim = "@@"
+	// prefix for lines added
+	addPrefix = "+"
+	// prefix for lines removed
+	remPrefix = "-"
+)
+
+// DiffOption provides a way for setting specific options during a diff
+// operation. Each supported option can customize the way the diff is
+// executed against the current repository (working directory)
+type DiffOption func(*diffOptions)
+
+type diffOptions struct {
+	DiffPaths []string
+}
+
+// WithDiffPaths allows the diff to be targeted to specific files and
+// folers within the current repository (working directory). Paths to
+// files and folders are relative to the root of the repository. All
+// leading and trailing whitepsace will be trimmed from the file paths,
+// allowing empty paths to be ignored
+func WithDiffPaths(paths ...string) DiffOption {
+	return func(opts *diffOptions) {
+		opts.DiffPaths = trim(paths...)
+	}
+}
+
+// FileDiff represents a snapshot containing all of the changes to
+// a file within a repository (working directory)
+type FileDiff struct {
+	// Path of the file within the repository (working directory)
+	Path string
+
+	// DiffChunk contains all of the identified changes within
+	// the file
+	Chunks []DiffChunk
+}
+
+// DiffChunk represents a snapshot of a single change (chunk) to
+// a file within a repository (working directory)
+type DiffChunk struct {
+	// Added optionally contains details of the text that has
+	// been added to a file as part of the current change
+	Added DiffChange
+
+	// Removed optionally contains details of the text that has
+	// been removed from a file as part of the current change
+	Removed DiffChange
+}
+
+// DiffChange captures details about an individual chunk
+// within a git diff. It contains both the changed text and
+// its exact position (and line count) within the file
+type DiffChange struct {
+	// LineNo is the position within the file where the
+	// change starts
+	LineNo int
+
+	// Count is the number of lines that has changed
+	Count int
+
+	// Change contains the text that has changed
+	Change string
+}
+
+// Diff captures the changes made to files within the current repository (working
+// directory). Options can be provided to customize how the current diff is
+// determined. By default, all diffs (or changes) to files within the repository
+// will be retrieved. The diff is generated using the following git options:
+//
+//	git diff -U0 --no-color
+func (c *Client) Diff(opts ...DiffOption) ([]FileDiff, error) {
+	options := &diffOptions{}
+	for _, opt := range opts {
+		opt(options)
+	}
+
+	var buf strings.Builder
+	buf.WriteString("git diff -U0 --no-color")
+
+	if len(options.DiffPaths) > 0 {
+		buf.WriteString(" -- ")
+		buf.WriteString(strings.Join(options.DiffPaths, " "))
+	}
+
+	out, err := c.exec(buf.String())
+	if err != nil {
+		return nil, err
+	}
+	return parseDiffs(out)
+}
+
+func parseDiffs(log string) ([]FileDiff, error) {
+	var diffs []FileDiff
+
+	scanner := bufio.NewScanner(strings.NewReader(log))
+	scanner.Split(scan.DiffLines())
+
+	for scanner.Scan() {
+		diff, err := parseDiff(scanner.Text())
+		if err != nil {
+			return nil, err
+		}
+
+		diffs = append(diffs, diff)
+	}
+
+	return diffs, nil
+}
+
+func parseDiff(diff string) (FileDiff, error) {
+	rem, path, err := diffPath()(diff)
+	if err != nil {
+		return FileDiff{}, err
+	}
+
+	rem, _, err = chomp.Until(hdrDelim)(rem)
+	if err != nil {
+		return FileDiff{}, err
+	}
+
+	chunks, err := diffChunks(rem)
+	if err != nil {
+		return FileDiff{}, err
+	}
+
+	return FileDiff{
+		Path:   path,
+		Chunks: chunks,
+	}, nil
+}
+
+func diffPath() chomp.Combinator[string] {
+	return func(s string) (string, string, error) {
+		var rem string
+		var err error
+
+		if rem, _, err = chomp.Tag("diff --git ")(s); err != nil {
+			return rem, "", err
+		}
+
+		var path string
+		if rem, path, err = chomp.Until(" ")(rem); err != nil {
+			return rem, "", err
+		}
+		path = path[strings.Index(path, "/")+1:]
+
+		rem, _, err = chomp.Eol()(rem)
+		return rem, path, err
+	}
+}
+
+func diffChunks(in string) ([]DiffChunk, error) {
+	_, chunks, err := chomp.Map(chomp.Many(diffChunk()),
+		func(in []string) []DiffChunk {
+			var diffChunks []DiffChunk
+
+			for i := 0; i+5 < len(in); i += 6 {
+				chunk := DiffChunk{
+					Removed: DiffChange{
+						LineNo: mustInt(in[i]),
+						Count:  mustInt(in[i+1]),
+						Change: in[i+4],
+					},
+					Added: DiffChange{
+						LineNo: mustInt(in[i+2]),
+						Count:  mustInt(in[i+3]),
+						Change: in[i+5],
+					},
+				}
+
+				if chunk.Added.Count == 0 {
+					chunk.Added.Count = 1
+				}
+
+				if chunk.Removed.Count == 0 {
+					chunk.Removed.Count = 1
+				}
+
+				diffChunks = append(diffChunks, chunk)
+			}
+
+			return diffChunks
+		},
+	)(in)
+
+	return chunks, err
+}
+
+func mustInt(in string) int {
+	out, _ := strconv.Atoi(in)
+	return out
+}
+
+func diffChunk() chomp.Combinator[[]string] {
+	return func(s string) (string, []string, error) {
+		var rem string
+		var err error
+
+		var changes []string
+		rem, changes, err = chomp.Delimited(
+			chomp.Tag(hdrDelim+" "),
+			chomp.SepPair(diffChunkHeaderChange(remPrefix), chomp.Tag(" "), diffChunkHeaderChange(addPrefix)),
+			chomp.Eol(),
+		)(s)
+		if err != nil {
+			return rem, nil, err
+		}
+
+		var removed string
+		rem, removed, err = chomp.Map(
+			chomp.ManyN(chomp.Prefixed(chomp.Eol(), chomp.Tag(remPrefix)), 0),
+			func(in []string) string { return strings.Join(in, "\n") },
+		)(rem)
+		if err != nil {
+			return rem, nil, err
+		}
+
+		var added string
+		rem, added, err = chomp.Map(
+			chomp.ManyN(chomp.Prefixed(chomp.Eol(), chomp.Tag(addPrefix)), 0),
+			func(in []string) string { return strings.Join(in, "\n") },
+		)(rem)
+		if err != nil {
+			return rem, nil, err
+		}
+
+		return rem, append(changes, removed, added), nil
+	}
+}
+
+func diffChunkHeaderChange(prefix string) chomp.Combinator[[]string] {
+	return func(s string) (string, []string, error) {
+		rem, _, err := chomp.Tag(prefix)(s)
+		if err != nil {
+			return rem, nil, err
+		}
+
+		return chomp.All(
+			chomp.While(chomp.IsDigit),
+			chomp.Opt(chomp.Prefixed(chomp.While(chomp.IsDigit), chomp.Tag(","))),
+		)(rem)
+	}
+}

diff_test.go

@@ -0,0 +1,83 @@
+package git_test
+
+import (
+	"testing"
+
+	git "github.com/purpleclay/gitz"
+	"github.com/purpleclay/gitz/gittest"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDiff(t *testing.T) {
+	gittest.InitRepository(t,
+		gittest.WithCommittedFiles("main.go"),
+		gittest.WithFileContent("main.go", `package main
+
+import "fmt"
+
+func print() {
+	fmt.Println("Hello, World!")
+}
+
+func main() {
+	print()
+}`))
+
+	overwriteFile(t, "main.go", `package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	fmt.Printf("Hello, %s\n" + os.Args[1])
+}`)
+
+	client, _ := git.NewClient()
+	diffs, err := client.Diff()
+	require.NoError(t, err)
+
+	require.Len(t, diffs, 1)
+	assert.Equal(t, "main.go", diffs[0].Path)
+
+	require.Len(t, diffs[0].Chunks, 2)
+	assert.Equal(t, 3, diffs[0].Chunks[0].Added.LineNo)
+	assert.Equal(t, 4, diffs[0].Chunks[0].Added.Count)
+	assert.Equal(t, `import (
+	"fmt"
+	"os"
+)`, diffs[0].Chunks[0].Added.Change)
+
+	assert.Equal(t, 3, diffs[0].Chunks[0].Removed.LineNo)
+	assert.Equal(t, 5, diffs[0].Chunks[0].Removed.Count)
+	assert.Equal(t, `import "fmt"
+
+func print() {
+	fmt.Println("Hello, World!")
+}`, diffs[0].Chunks[0].Removed.Change)
+
+	assert.Equal(t, 9, diffs[0].Chunks[1].Added.LineNo)
+	assert.Equal(t, 1, diffs[0].Chunks[1].Added.Count)
+	assert.Equal(t, `	fmt.Printf("Hello, %s\n" + os.Args[1])`, diffs[0].Chunks[1].Added.Change)
+
+	assert.Equal(t, 10, diffs[0].Chunks[1].Removed.LineNo)
+	assert.Equal(t, 1, diffs[0].Chunks[1].Removed.Count)
+	assert.Equal(t, `	print()`, diffs[0].Chunks[1].Removed.Change)
+}
+
+func TestDiffWithDiffPaths(t *testing.T) {
+	gittest.InitRepository(t,
+		gittest.WithCommittedFiles("file1.txt", "file2.txt"),
+		gittest.WithFileContent("file1.txt", "Hello, World!", "file2.txt", "Goodbye, World!"))
+
+	overwriteFile(t, "file1.txt", "Goodbye, World!")
+	overwriteFile(t, "file2.txt", "Hello, World!")
+
+	client, _ := git.NewClient()
+	diffs, err := client.Diff(git.WithDiffPaths("file1.txt"))
+	require.NoError(t, err)
+
+	assert.Len(t, diffs, 1)
+}

gittest/log.go

@@ -1,25 +1,3 @@
-/*
-Copyright (c) 2023 Purple Clay
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
-*/
-
 package gittest
 
 import (

gittest/log_test.go

@@ -1,25 +1,3 @@
-/*
-Copyright (c) 2023 Purple Clay
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
-*/
-
 package gittest_test
 
 import (