package main

import (
	"bytes"
	"flag"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"

	"9fans.net/go/acme"
	"github.com/akedrou/textdiff"
)

var (
	fl_lang    = flag.String("l", "C", "Language")
	fl_verbose = flag.Bool("v", false, "Verbosity on")

	pos_rx = regexp.MustCompile(`.* orig line is ([\d]+), orig col is ([\d]+)`)
	lin_rx = regexp.MustCompile(`.* orig line is ([\d]+)`)
	grb_rx = regexp.MustCompile(`stdin:([\d]+) Garbage in col ([\d]+)`)
)

func main() {
	flag.Parse()

	samfile := os.Getenv("samfile")
	id := os.Getenv("winid")
	if "" == id {
		log.Fatalf("no $winid set, not running in acme?")
	}

	wid, e := strconv.Atoi(id)
	if e != nil {
		log.Fatalf("couldn't parse $winid: %s\n", e)
	}

	win, e := acme.Open(wid, nil)
	if e != nil {
		log.Fatalf("couldn't open acme window id %d: %s\n", wid, e)
	}

	body, e := win.ReadAll("body")
	if e != nil {
		log.Fatalf("couldn't read body of window id %d: %s\n", wid, e)
	}

	args := []string{"--replace", "--no-backup", "-l", *fl_lang}
	stderr := &bytes.Buffer{}
	stdout := &bytes.Buffer{}

	cmd := exec.Command("uncrustify", args...)
	cmd.Stdin = bytes.NewBuffer(body)
	cmd.Stdout = stdout
	cmd.Stderr = stderr

	samfile = filepath.Base(samfile)

	if e = cmd.Run(); e != nil {
		if _, ok := e.(*exec.ExitError); ok {
			str := stderr.String()
			str += "\n" + stdout.String()
			if len(samfile) != 0 {
				str = strings.ReplaceAll(str, "stdin, open_line is ", samfile+":")
				str = pos_rx.ReplaceAllString(str, fmt.Sprintf("%s:$1:#$2", samfile))
				str = lin_rx.ReplaceAllString(str, fmt.Sprintf("%s:$1", samfile))
				str = grb_rx.ReplaceAllString(str, fmt.Sprintf("%s:$1:#$2", samfile))
			}
			log.Fatal("error: " + str)
		}
		log.Fatalf("error: %s\n", e)
		return
	}

	after := stdout.String()
	before := string(body)
	edits := textdiff.Strings(before, after)
	textdiff.SortEdits(edits)

	// We have to calculate the rune position from the byte position.
	rcount := 0
	sidx, eidx := 0, 0
	for p := range before {
		for i := range edits[sidx:] {
			if edits[sidx+i].Start == p {
				edits[sidx+i].Start = rcount
				sidx += i
				break
			}
		}
		for i := range edits[eidx:] {
			if edits[i+eidx].End == p {
				edits[i+eidx].End = rcount
				eidx += i
				break
			}
		}
		rcount++
		if eidx == len(edits) {
			break
		}
	}

	if len(edits) > 0 {
		if *fl_verbose {
			log.Printf("Applying %d diffs:\n%s\n", len(edits), pretty(edits, samfile))
		}
		win.Write("ctl", []byte("mark"))
		win.Write("ctl", []byte("nomark"))
	}

	for i := len(edits) - 1; i >= 0; i-- {
		edit := edits[i]

		addr := fmt.Sprintf("#%d,#%d", edit.Start, edit.End)
		e = win.Addr(addr)
		if e != nil {
			log.Fatalf("error writing %q to acme/%d/addr: %s\n", addr, wid, e)
		}
		win.Write("data", []byte(edit.New))
	}
}

func pretty(e []textdiff.Edit, p string) string {
	b := &bytes.Buffer{}
	for _, e := range e {
		fmt.Fprintf(b, "%s:#%d,#%d: »%s«\n", p, e.Start, e.End, e.New)
	}
	return b.String()
}