move some packages to the "internal" directory

- this makes it impossible to import these packages outside Task
- as a side effect, it makes the root directory cleaner

internal/status/checksum.go

@@ -0,0 +1,83 @@
+package status
+
+import (
+	"crypto/md5"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+// Checksum validades if a task is up to date by calculating its source
+// files checksum
+type Checksum struct {
+	Dir     string
+	Task    string
+	Sources []string
+}
+
+// IsUpToDate implements the Checker interface
+func (c *Checksum) IsUpToDate() (bool, error) {
+	checksumFile := c.checksumFilePath()
+
+	data, _ := ioutil.ReadFile(checksumFile)
+	oldMd5 := strings.TrimSpace(string(data))
+
+	sources, err := glob(c.Dir, c.Sources)
+	if err != nil {
+		return false, err
+	}
+
+	newMd5, err := c.checksum(sources...)
+	if err != nil {
+		return false, nil
+	}
+
+	_ = os.MkdirAll(filepath.Join(c.Dir, ".task"), 0755)
+	if err = ioutil.WriteFile(checksumFile, []byte(newMd5+"\n"), 0644); err != nil {
+		return false, err
+	}
+	return oldMd5 == newMd5, nil
+}
+
+func (c *Checksum) checksum(files ...string) (string, error) {
+	h := md5.New()
+
+	for _, f := range files {
+		f, err := os.Open(f)
+		if err != nil {
+			return "", err
+		}
+		info, err := f.Stat()
+		if err != nil {
+			return "", err
+		}
+		if info.IsDir() {
+			continue
+		}
+		if _, err := io.Copy(h, f); err != nil {
+			return "", err
+		}
+	}
+
+	return fmt.Sprintf("%x", h.Sum(nil)), nil
+}
+
+// OnError implements the Checker interface
+func (c *Checksum) OnError() error {
+	return os.Remove(c.checksumFilePath())
+}
+
+func (c *Checksum) checksumFilePath() string {
+	return filepath.Join(c.Dir, ".task", c.normalizeFilename(c.Task))
+}
+
+var checksumFilenameRegexp = regexp.MustCompile("[^A-z0-9]")
+
+// replaces invalid caracters on filenames with "-"
+func (*Checksum) normalizeFilename(f string) string {
+	return checksumFilenameRegexp.ReplaceAllString(f, "-")
+}

internal/status/checksum_test.go

@@ -0,0 +1,21 @@
+package status
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNormalizeFilename(t *testing.T) {
+	tests := []struct {
+		In, Out string
+	}{
+		{"foobarbaz", "foobarbaz"},
+		{"foo/bar/baz", "foo-bar-baz"},
+		{"foo@bar/baz", "foo-bar-baz"},
+		{"foo1bar2baz3", "foo1bar2baz3"},
+	}
+	for _, test := range tests {
+		assert.Equal(t, test.Out, (&Checksum{}).normalizeFilename(test.In))
+	}
+}

internal/status/glob.go

@@ -0,0 +1,23 @@
+package status
+
+import (
+	"path/filepath"
+	"sort"
+
+	"github.com/mattn/go-zglob"
+)
+
+func glob(dir string, globs []string) (files []string, err error) {
+	for _, g := range globs {
+		if !filepath.IsAbs(g) {
+			g = filepath.Join(dir, g)
+		}
+		f, err := zglob.Glob(g)
+		if err != nil {
+			return nil, err
+		}
+		files = append(files, f...)
+	}
+	sort.Strings(files)
+	return
+}

internal/status/none.go

@@ -0,0 +1,14 @@
+package status
+
+// None is a no-op Checker
+type None struct{}
+
+// IsUpToDate implements the Checker interface
+func (None) IsUpToDate() (bool, error) {
+	return false, nil
+}
+
+// OnError implements the Checker interface
+func (None) OnError() error {
+	return nil
+}

internal/status/status.go

@@ -0,0 +1,13 @@
+package status
+
+var (
+	_ Checker = &Timestamp{}
+	_ Checker = &Checksum{}
+	_ Checker = None{}
+)
+
+// Checker is an interface that checks if the status is up-to-date
+type Checker interface {
+	IsUpToDate() (bool, error)
+	OnError() error
+}

internal/status/timestamp.go

@@ -0,0 +1,85 @@
+package status
+
+import (
+	"os"
+	"time"
+)
+
+// Timestamp checks if any source change compared with the generated files,
+// using file modifications timestamps.
+type Timestamp struct {
+	Dir       string
+	Sources   []string
+	Generates []string
+}
+
+// IsUpToDate implements the Checker interface
+func (t *Timestamp) IsUpToDate() (bool, error) {
+	if len(t.Sources) == 0 || len(t.Generates) == 0 {
+		return false, nil
+	}
+
+	sources, err := glob(t.Dir, t.Sources)
+	if err != nil {
+		return false, nil
+	}
+	generates, err := glob(t.Dir, t.Generates)
+	if err != nil {
+		return false, nil
+	}
+
+	sourcesMaxTime, err := getMaxTime(sources...)
+	if err != nil || sourcesMaxTime.IsZero() {
+		return false, nil
+	}
+
+	generatesMinTime, err := getMinTime(generates...)
+	if err != nil || generatesMinTime.IsZero() {
+		return false, nil
+	}
+
+	return !generatesMinTime.Before(sourcesMaxTime), nil
+}
+
+func getMinTime(files ...string) (time.Time, error) {
+	var t time.Time
+	for _, f := range files {
+		info, err := os.Stat(f)
+		if err != nil {
+			return time.Time{}, err
+		}
+		t = minTime(t, info.ModTime())
+	}
+	return t, nil
+}
+
+func getMaxTime(files ...string) (time.Time, error) {
+	var t time.Time
+	for _, f := range files {
+		info, err := os.Stat(f)
+		if err != nil {
+			return time.Time{}, err
+		}
+		t = maxTime(t, info.ModTime())
+	}
+	return t, nil
+}
+
+func minTime(a, b time.Time) time.Time {
+	if !a.IsZero() && a.Before(b) {
+		return a
+	}
+	return b
+}
+
+func maxTime(a, b time.Time) time.Time {
+	if a.After(b) {
+		return a
+	}
+	return b
+}
+
+// OnError implements the Checker interface
+func (*Timestamp) OnError() error {
+	return nil
+}