package main

import (
	_ "embed"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"regexp"
	"strings"
)

func _main(o opts) error {
	t, err := ioutil.ReadAll(o.In)
	if err != nil {
		return fmt.Errorf("could not read from stdin: %w", err)
	}

	r := regexp.MustCompile(`\(LINK ([^ ]+?) (.+?)\)`)
	mms := r.FindAllSubmatch(t, -1)

	if mms == nil {
		fmt.Fprintf(o.Out, string(t))
		return nil
	}

	output := string(t)

	for _, ms := range mms {
		switch o.Mode {
		case "html":
			output = strings.ReplaceAll(output, string(ms[0]),
				fmt.Sprintf("<a href=\"%s\">%s</a>", string(ms[1]), string(ms[2])))
		case "gopher":
			break
		case "gemini":
			break
		}
	}

	fmt.Fprintf(o.Out, output)

	return nil
}

type opts struct {
	In   io.Reader
	Out  io.Writer
	Mode string
}

func main() {
	// TODO mode flag
	var modeFlag = flag.String("mode", "", "one of html, gopher, gemini.")
	flag.Parse()
	if *modeFlag == "" || (*modeFlag != "html" && *modeFlag != "gopher" && *modeFlag != "gemini") {
		fmt.Fprintln(os.Stderr, "--mode must be specified and one of: html, gopher, gemini")
		os.Exit(1)
	}
	o := opts{
		In:   os.Stdin,
		Out:  os.Stdout,
		Mode: *modeFlag,
	}
	if err := _main(o); err != nil {
		fmt.Fprintln(os.Stderr, err.Error())
		os.Exit(2)
	}
}