// +build ignore

package main

import (
	"bytes"
	"fmt"
	"go/parser"
	"go/token"
	"io/ioutil"
	"log"
	"os"
	"sort"

	"github.com/dave/dst"
	"github.com/dave/dst/decorator"
)

func main() {
	var file string
	for _, arg := range os.Args[1:] {
		if arg != "--" {
			file = arg
			break
		}
	}

	if file == "" {
		fmt.Fprintf(os.Stderr, "usage %s <file>\n", os.Args[0])
		os.Exit(1)
	}

	fset := token.NewFileSet()
	f, err := decorator.ParseFile(fset, file, nil, parser.ParseComments)
	must(err)

	for i := 0; i < len(f.Decls); i++ {
		if !isFuncDecl(f.Decls[i]) {
			continue
		}

		j := i
		for j < len(f.Decls) && isFuncDecl(f.Decls[j]) {
			j++
		}

		funcs := f.Decls[i:j]
		sort.Slice(funcs, func(i, j int) bool {
			return funcs[i].(*dst.FuncDecl).Name.Name <
				funcs[j].(*dst.FuncDecl).Name.Name
		})

		i = j
	}

	for _, d := range f.Decls {
		g, ok := d.(*dst.GenDecl)
		if !ok || g.Tok != token.VAR {
			continue
		}

		for _, s := range g.Specs {
			v, ok := s.(*dst.ValueSpec)
			if !ok {
				continue
			}

			for _, vv := range v.Values {
				c, ok := vv.(*dst.CompositeLit)
				if !ok {
					continue
				}

				_, ok = c.Type.(*dst.MapType)
				if !ok {
					continue
				}

				sort.Slice(c.Elts, func(i, j int) bool {
					return c.Elts[i].(*dst.KeyValueExpr).Key.(*dst.Ident).Name <
						c.Elts[j].(*dst.KeyValueExpr).Key.(*dst.Ident).Name
				})
			}
		}
	}

	var buf bytes.Buffer
	must(decorator.Fprint(&buf, f))
	must(ioutil.WriteFile(file, buf.Bytes(), 0644))
}

func isFuncDecl(d dst.Decl) bool {
	_, ok := d.(*dst.FuncDecl)
	return ok
}

func must(err error) {
	if err != nil {
		log.Fatal(err)
	}
}