[cmd] Add gotmpl to generate code using template

- mainly after https://github.com/benbjohnson/tmpl use go/format
- used by gommon log dyweb/gommon#17 to
generate different log level
- follow go's generated code standard, add special header
- comment out usage of `go.rice` in `Ayi install`

.ayi.yml

@@ -4,8 +4,9 @@ dep-install:
     - go get github.com/mitchellh/gox
     - glide install
 install:
-    - go build -o Ayi 
-    - rice append -i github.com/dyweb/Ayi/app/web --exec Ayi
+    - go build -o Ayi
+# disable it for now
+#    - rice append -i github.com/dyweb/Ayi/app/web --exec Ayi
     - sh -c "mv Ayi $GOPATH/bin/Ayi"
 test:
     - go install

cmd/gotmpl.go

@@ -0,0 +1,82 @@
+package cmd
+
+import (
+	"github.com/spf13/cobra"
+	"encoding/json"
+	"io/ioutil"
+	"html/template"
+	"bytes"
+	"strings"
+	"go/format"
+	"fmt"
+)
+
+// generate go file using go's built in template, port from https://github.com/benbjohnson/tmpl
+
+var gotmplData string
+var gotmplDataPath string
+
+var gotmplCmd = &cobra.Command{
+	Use:   "gotmpl",
+	Short: "generate go file using text/template",
+	Long:  "generate go file using text/template",
+	Run: func(cmd *cobra.Command, args []string) {
+		log.Info("go tmpl!")
+		if len(args) < 1 {
+			log.Fatal("must provide template file path i.e. logger_gen.go.tmpl")
+		}
+		src := args[0]
+		dst := strings.TrimSuffix(src, ".tmpl")
+		if src == dst || !strings.HasSuffix(dst, ".go") {
+			log.Fatal("only template for go code is supported")
+		}
+		// parse data
+		var data interface{}
+		if gotmplDataPath != "" {
+			json.Unmarshal(mustRead(gotmplDataPath), &data)
+		} else if gotmplData != "" {
+			json.Unmarshal([]byte(gotmplData), &data)
+		} else {
+			log.Fatal("no data specified")
+		}
+		log.Debugf("data %v", data)
+		// load template
+		source := mustRead(src)
+		// render template
+		tmpl, err := template.New("main").Parse(string(source))
+		if err != nil {
+			log.Fatalf("invalid template %s %v", src, err)
+		}
+		var buf bytes.Buffer
+		// standard header, as suggested by https://github.com/golang/go/issues/13560#issuecomment-288457920
+		buf.WriteString(fmt.Sprintf("// Code generated by Ayi gotmpl from %s DO NOT EDIT.\n", src))
+		if err := tmpl.Execute(&buf, data); err != nil {
+			log.Fatalf("can't render template %v", err)
+		}
+		formatted, err := format.Source(buf.Bytes())
+		if err != nil {
+			log.Fatalf("can't format code %v", err)
+		}
+		// stat -c %a pkg.go
+		if err := ioutil.WriteFile(dst, formatted, 644); err != nil {
+			log.Fatalf("can't write generated code to %s %v", dst, err)
+		}
+	},
+}
+
+func mustRead(p string) []byte {
+	if b, err := ioutil.ReadFile(p); err != nil {
+		log.Fatalf("can't read %s %v", p, err)
+		return nil
+	} else {
+		return b
+	}
+}
+
+func init() {
+	RootCmd.AddCommand(gotmplCmd)
+
+	gotmplCmd.Flags().StringVar(&gotmplData, "data", "", "data in json")
+	gotmplCmd.Flags().StringVar(&gotmplDataPath, "datap", "", "data (json) file path")
+
+}