implement macros & includes

pkg/mark/includes/templates.go

@@ -0,0 +1,155 @@
+package includes
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"text/template"
+
+	"gopkg.in/yaml.v2"
+
+	"github.com/kovetskiy/mark/pkg/log"
+	"github.com/reconquest/karma-go"
+)
+
+var (
+	reIncludeDirective = regexp.MustCompile(`(?s)<!-- Include: (\S+)(.*?)-->`)
+)
+
+func LoadTemplate(
+	path string,
+	templates *template.Template,
+) (string, *template.Template, error) {
+	var (
+		name  = strings.TrimSuffix(path, filepath.Ext(path))
+		facts = karma.Describe("name", name)
+	)
+
+	if template := templates.Lookup(name); template != nil {
+		return name, template, nil
+	}
+
+	var body []byte
+
+	body, err := ioutil.ReadFile(path)
+	if err != nil {
+		err = facts.Format(
+			err,
+			"unable to read template file",
+		)
+
+		return name, nil, err
+	}
+
+	templates, err = templates.New(name).Parse(string(body))
+	if err != nil {
+		err = facts.Format(
+			err,
+			"unable to parse template",
+		)
+
+		return name, nil, err
+	}
+
+	return name, templates, nil
+}
+
+func ProcessIncludes(
+	contents []byte,
+	templates *template.Template,
+) (*template.Template, []byte, bool, error) {
+	vardump := func(
+		facts *karma.Context,
+		data map[string]interface{},
+	) *karma.Context {
+		for key, value := range data {
+			key = "var " + key
+			facts = facts.Describe(
+				key,
+				strings.ReplaceAll(
+					fmt.Sprint(value),
+					"\n",
+					"\n"+strings.Repeat(" ", len(key)+2),
+				),
+			)
+		}
+
+		return facts
+	}
+
+	var (
+		recurse bool
+		err     error
+	)
+
+	contents = reIncludeDirective.ReplaceAllFunc(
+		contents,
+		func(spec []byte) []byte {
+			if err != nil {
+				return nil
+			}
+
+			groups := reIncludeDirective.FindSubmatch(spec)
+
+			var (
+				path, config = string(groups[1]), groups[2]
+				data         = map[string]interface{}{}
+
+				facts = karma.Describe("path", path)
+			)
+
+			err = yaml.Unmarshal(config, &data)
+			if err != nil {
+				err = facts.
+					Describe("config", string(config)).
+					Format(
+						err,
+						"unable to unmarshal template data config",
+					)
+
+				return nil
+			}
+
+			log.Tracef(vardump(facts, data), "including template %q", path)
+
+			var name string
+
+			name, templates, err = LoadTemplate(path, templates)
+			if err != nil {
+				err = facts.Format(err, "unable to load template")
+
+				return nil
+			}
+
+			facts = facts.Describe("name", name)
+
+			template := templates.Lookup(string(name))
+			if template == nil {
+				err = facts.Reason("template not found")
+
+				return nil
+			}
+
+			var buffer bytes.Buffer
+
+			err = template.Execute(&buffer, data)
+			if err != nil {
+				err = vardump(facts, data).Format(
+					err,
+					"unable to execute template",
+				)
+
+				return nil
+			}
+
+			recurse = true
+
+			return buffer.Bytes()
+		},
+	)
+
+	return templates, contents, recurse, err
+}