// SPDX-License-Identifier: Unlicense

package main

import (
	"bytes"
	_ "embed"
	"errors"
	"flag"
	"fmt"
	"go/format"
	"os"
	"strconv"
	"text/template"
)

//go:embed bind.go.tmpl
var bind string

//go:embed seq.go.tmpl
var seq string

var bindTmpl, seqTmpl *template.Template

func main() {
	err := run()
	if err != nil {
		fmt.Fprint(os.Stderr, err)
		os.Exit(1)
	}
}

func run() error {
	bindPath := flag.String("bindpath", "", "bind file path")
	seqPath := flag.String("seqpath", "", "seq file path")
	maxBindLen := flag.Int("max", 0, "max bind length")
	pkg := flag.String("pkg", "", "output package")
	flag.Parse()

	if *bindPath == "" {
		return errors.New("bindpath required")
	}
	if *seqPath == "" {
		return errors.New("seqpath required")
	}
	if *maxBindLen == 0 {
		return errors.New("maxbind required")
	}
	if *pkg == "" {
		return errors.New("pkg required")
	}

	bindTmpl = template.Must(template.New("bind").Parse(bind))
	seqTmpl = template.Must(template.New("seq").Parse(seq))

	data := File{
		Package: *pkg,
		Counter: Counter(*maxBindLen),
	}
	err := genCodeFile(*bindPath, bindTmpl, data)
	if err != nil {
		return err
	}
	return genCodeFile(*seqPath, seqTmpl, data)
}

func genCodeFile(path string, tmpl *template.Template, data any) error {
	var buf bytes.Buffer
	err := tmpl.Execute(&buf, data)
	if err != nil {
		return err
	}
	src, err := format.Source(buf.Bytes())
	if err != nil {
		return err
	}
	return os.WriteFile(path, src, 0777)
}

type File struct {
	Package string
	Counter
}

// func (f File) Funcs() []Func {
// 	counters := f.Max.Count()
// 	funcs := make([]Func, len(counters))
// 	for i, counter := range counters {
// 		funcs[i] = Func{
// 			Max:    f.Max,
// 			Length: counter,
// 		}
// 	}
// 	return funcs
// }

type Func struct {
	Max    Counter
	Length Counter
}

type Counter int

func (c Counter) String() string {
	if c == 1 {
		return ""
	}
	return strconv.Itoa(int(c))
}

func (c Counter) Int() int {
	return int(c)
}

func (c Counter) Next() Counter {
	return c + 1
}

func (c Counter) Prev() Counter {
	return c - 1
}

func (c Counter) Count() []Counter {
	a := make([]Counter, c)
	for i := range a {
		a[i] = Counter(i + 1)
	}
	return a
}