From 32ddef5ca7f20a9aa0e7b80484e59d1653e856e4 Mon Sep 17 00:00:00 2001
From: Ajitem Sahasrabuddhe <ajitem.sahasrabuddhe@perennialsys.com>
Date: Sat, 3 Aug 2019 21:48:48 +0530
Subject: [PATCH] finish generation of flag types for cli package

---
 flaggen/flag_generated.gotpl |   0
 flaggen/main.go              | 147 +++++++++++++++++++++++++++++++++--
 2 files changed, 142 insertions(+), 5 deletions(-)
 create mode 100644 flaggen/flag_generated.gotpl

diff --git a/flaggen/flag_generated.gotpl b/flaggen/flag_generated.gotpl
new file mode 100644
index 0000000..e69de29
diff --git a/flaggen/main.go b/flaggen/main.go
index 02af0d8..cbaba90 100644
--- a/flaggen/main.go
+++ b/flaggen/main.go
@@ -1,28 +1,165 @@
 package main
 
 import (
+	"encoding/json"
 	"github.com/urfave/cli"
 	"log"
 	"os"
+	"text/template"
 )
 
+type CliFlagInfo struct {
+	PackageName string
+	Flags       []FlagType
+}
+
+type FlagType struct {
+	Name           string `json:"name"`
+	Type           string `json:"type"`
+	Value          bool   `json:"value"`
+	Destination    bool   `json:"dest"`
+	Doctail        string `json:"doctail"`
+	ContextDefault string `json:"context_default"`
+	ContextType    string `json:"context_type"`
+	Parser         string `json:"parser"`
+	ParserCast     string `json:"parser_cast"`
+}
+
+var cliFlagTemplate = `// Code generated by fg; DO NOT EDIT.
+
+package {{ .PackageName }}
+
+import (
+	"flag"
+	"strconv"
+	"time"
+)
+{{ range $i, $flag := .Flags }}
+// {{ $flag.Name }}Flag is a flag with type {{ $flag.Type }}{{ $flag.Doctail }}
+type {{ $flag.Name }}Flag struct {
+    Name        string
+    Usage       string
+    EnvVar      string
+    FilePath    string
+    Required    bool
+    Hidden      bool
+    {{- if eq $flag.Value true }}
+	Value		{{ $flag.Type }}
+	{{- end }}
+	{{- if eq $flag.Destination true }}
+	Destination	*{{ $flag.Type }}
+	{{- end }}
+}
+
+// String returns a readable representation of this value
+// (for usage defaults)
+func (f {{ $flag.Name }}Flag) String() string {
+    return FlagStringer(f)
+}
+
+// GetName returns the name of the flag
+func (f {{ $flag.Name }}Flag) GetName() string {
+    return f.Name
+}
+
+// IsRequired returns whether or not the flag is required
+func (f {{ $flag.Name }}Flag) IsRequired() bool {
+    return f.Required
+}
+
+// {{ $flag.Name }} looks up the value of a local {{ $flag.Name }}Flag, returns
+// {{ $flag.ContextDefault }} if not found
+func (c *Context) {{ $flag.Name }}(name string) {{ if ne .ContextType "" }} {{ $flag.ContextType }} {{ else }} {{ $flag.Type }} {{- end }} {
+    return lookup{{ $flag.Name }}(name, c.flagSet)
+}
+
+// Global{{ $flag.Name }} looks up the value of a global {{ $flag.Name }}Flag, returns
+// {{ $flag.ContextDefault }} if not found
+func (c *Context) Global{{ $flag.Name }}(name string) {{ if ne .ContextType "" }} {{ $flag.ContextType }} {{ else }} {{ $flag.Type }} {{- end }} {
+    if fs := lookupGlobalFlagSet(name, c); fs != nil {
+        return lookup{{ $flag.Name }}(name, fs)
+    }
+    return {{ $flag.ContextDefault }}
+}
+
+func lookup{{ $flag.Name }}(name string, set *flag.FlagSet) {{ if ne .ContextType "" }} {{ $flag.ContextType }} {{ else }} {{ $flag.Type }} {{- end }} {
+    f := set.Lookup(name)
+    if f != nil {
+        {{ if ne .Parser "" }}parsed, err := {{ $flag.Parser }}{{ else }}parsed, err := f.Value, error(nil){{ end }}
+        if err != nil {
+            return {{ $flag.ContextDefault }}
+        }
+        {{ if ne .ParserCast "" }}return {{ $flag.ParserCast }}{{ else }}return parsed{{ end }}
+    }
+    return {{ $flag.ContextDefault }}
+}
+{{- end }}`
+
 func main() {
+	var packageName, inputPath, outputPath string
+
 	app := cli.NewApp()
 
-	app.Name = "flaggen"
+	app.Name = "fg"
 	app.Usage = "Generate flag type code!"
+	app.Version = "v0.1.0"
 
 	app.Flags = []cli.Flag{
 		cli.StringFlag{
-			Name:  "package, p",
-			Value: "cli",
-			Usage: "`Name of the package` for which the flag types will be generated",
+			Name:        "package, p",
+			Value:       "cli",
+			Usage:       "`PACKAGE` for which the flag types will be generated",
+			Destination: &packageName,
+		},
+		cli.StringFlag{
+			Name:        "input, i",
+			Usage:       "path to the `INPUT JSON FILE` which defines each type to be generated",
+			Destination: &inputPath,
+		},
+		cli.StringFlag{
+			Name:        "output, o",
+			Usage:       "path to the `OUTPUT GO FILE` which will contain the flag types",
+			Destination: &outputPath,
 		},
 	}
 
+	app.Action = func(c *cli.Context) error {
+		var info CliFlagInfo
+		info.PackageName = packageName
+
+		inFile, err := os.Open(inputPath)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		defer inFile.Close()
+
+		decoder := json.NewDecoder(inFile)
+
+		err = decoder.Decode(&info.Flags)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		tpl := template.Must(template.New("").Parse(cliFlagTemplate))
+
+		outFile, err := os.Create(outputPath)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		defer outFile.Close()
+
+		err = tpl.Execute(outFile, info)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		return nil
+	}
+
 	err := app.Run(os.Args)
 	if err != nil {
 		log.Fatal(err)
 	}
-
 }