main.go

/*
Unindents selected source code.

`a+` and `a-` use your indentation settings to indent or unindent
your selection in acme using either tabs or spaces depending on
what is configured. To use these commands, write `|a+` or `|a-` to
the scratch area in your acme window, select the text you want to
indent, and then middle click on `|a+` to indent or `|a-` to unindent
your selection. These commands are also used by `nynetab` for
indenting/unindenting text depending on the provided flags.
*/
package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strconv"

	"github.com/dnjp/nyne"
)

func main() {
	filename := os.Getenv("samfile")
	if filename == "" {
		filename = os.Getenv("%")
	}
	if filename == "" {
		fmt.Fprintf(os.Stderr, "$samfile and $%% are empty. are you sure you're in acme?")
		os.Exit(1)
	}

	ft, _ := nyne.FindFiletype(nyne.Filename(filename))
	tw := ft.Tabwidth
	te := ft.Tabexpand
	if tw == 0 {
		tab := os.Getenv("tabstop")
		if tab == "" {
			tw = 8
		} else {
			ntw, err := strconv.Atoi(tab)
			if err != nil {
				panic(fmt.Errorf("invalid $tabstop: %v", err))
			}
			tw = ntw
		}
	}

	tab := nyne.Tab(tw, te)
	var i, indentidx, lastnl, indentc, nlc int
	lastnl = -1
	buf := make([]byte, 0)
	reader := bufio.NewReader(os.Stdin)
	for {
		b, err := reader.ReadByte()
		if err != nil && err == io.EOF {
			break
		}
		if b == '\n' {
			nlc++
			lastnl = i
		}
		inindent := b == tab[indentidx]
		if i == 0 && inindent || ((i > 0 && i-1 == lastnl) && inindent) {
			indentidx++
			if indentidx == len(tab) {
				buf = make([]byte, 0)
				indentidx = 0
				indentc++
			}
			buf = append(buf, b)
			i++
			continue
		} else if indentidx > 0 || len(buf) > 0 {
			buf = make([]byte, 0)
			indentidx = 0
		}
		fmt.Fprintf(os.Stdout, "%c", b)
		i++
	}
}