implement macros & includes

pkg/mark/macro/macro.go

@@ -0,0 +1,162 @@
+package macro
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+	"strings"
+	"text/template"
+
+	"github.com/kovetskiy/mark/pkg/log"
+	"github.com/kovetskiy/mark/pkg/mark/includes"
+	"github.com/reconquest/karma-go"
+	"gopkg.in/yaml.v2"
+)
+
+var reMacroDirective = regexp.MustCompile(
+	`(?s)<!-- Macro: ([^\n]+)\n\s*Template: (\S+)\n(.*?)-->`,
+)
+
+type Macro struct {
+	Regexp   *regexp.Regexp
+	Template *template.Template
+	Config   map[string]interface{}
+}
+
+func (macro *Macro) Apply(
+	content []byte,
+) ([]byte, error) {
+	var err error
+
+	content = macro.Regexp.ReplaceAllFunc(
+		content,
+		func(match []byte) []byte {
+			config := macro.configure(
+				macro.Config,
+				macro.Regexp.FindSubmatch(match),
+			)
+
+			var buffer bytes.Buffer
+
+			err = macro.Template.Execute(&buffer, config)
+			if err != nil {
+				err = karma.Format(
+					err,
+					"unable to execute macros template",
+				)
+			}
+
+			return buffer.Bytes()
+		},
+	)
+
+	return content, err
+}
+
+func (macro *Macro) configure(node interface{}, groups [][]byte) interface{} {
+	switch node := node.(type) {
+	case map[interface{}]interface{}:
+		for key, value := range node {
+			node[key] = macro.configure(value, groups)
+		}
+
+		return node
+	case map[string]interface{}:
+		for key, value := range node {
+			node[key] = macro.configure(value, groups)
+		}
+
+		return node
+	case []interface{}:
+		for key, value := range node {
+			node[key] = macro.configure(value, groups)
+		}
+
+		return node
+	case string:
+		for i, group := range groups {
+			node = strings.ReplaceAll(
+				node,
+				fmt.Sprintf("${%d}", i),
+				string(group),
+			)
+		}
+
+		return node
+	}
+
+	return node
+}
+
+func LoadMacros(
+	contents []byte,
+	templates *template.Template,
+) ([]Macro, []byte, error) {
+	var err error
+
+	var macros []Macro
+
+	contents = reMacroDirective.ReplaceAllFunc(
+		contents,
+		func(spec []byte) []byte {
+			if err != nil {
+				return spec
+			}
+
+			groups := reMacroDirective.FindSubmatch(spec)
+
+			var (
+				expr, path, config = groups[1], string(groups[2]), groups[3]
+
+				macro Macro
+			)
+
+			_, macro.Template, err = includes.LoadTemplate(path, templates)
+
+			if err != nil {
+				err = karma.Format(err, "unable to load template")
+
+				return nil
+			}
+
+			facts := karma.
+				Describe("template", path).
+				Describe("expr", string(expr))
+
+			macro.Regexp, err = regexp.Compile(string(expr))
+			if err != nil {
+				err = facts.
+					Format(
+						err,
+						"unable to compile macros regexp",
+					)
+
+				return nil
+			}
+
+			err = yaml.Unmarshal(config, &macro.Config)
+			if err != nil {
+				err = facts.
+					Describe("config", string(config)).
+					Format(
+						err,
+						"unable to unmarshal template data config",
+					)
+
+				return nil
+			}
+
+			log.Tracef(
+				facts.Describe("config", macro.Config),
+				"loaded macro %q",
+				expr,
+			)
+
+			macros = append(macros, macro)
+
+			return []byte{}
+		},
+	)
+
+	return macros, contents, err
+}