package main

import (
	"fmt"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"

	"github.com/VeraeLLC/PrintToVeraeTimeStamp/internal/job"
	"github.com/VeraeLLC/PrintToVeraeTimeStamp/internal/settings"
	"github.com/VeraeLLC/PrintToVeraeTimeStamp/internal/vlog"
)

// saveNameFromTitle turns a print-job title into a file name for the Save As
// dialog: path and extension dropped, app prefixes ("Microsoft Word - ")
// removed, characters invalid in file names replaced; empty titles fall back
// to "Printed YYYY-MM-DD HHMMSS".
func saveNameFromTitle(title string, now time.Time) string {
	t := strings.TrimSpace(title)
	for _, p := range []string{"Microsoft Word - ", "Microsoft Excel - ", "Microsoft PowerPoint - "} {
		t = strings.TrimPrefix(t, p)
	}
	t = path.Base(strings.ReplaceAll(t, `\`, "/")) // slash-only: "a:b" is not a drive here
	if ext := filepath.Ext(t); ext != "" && len(ext) <= 6 && !strings.ContainsAny(ext, " ") {
		t = strings.TrimSuffix(t, ext)
	}
	t = strings.Map(func(r rune) rune {
		if r < 32 || strings.ContainsRune(`<>:"/\|?*`, r) {
			return '-'
		}
		return r
	}, t)
	if rs := []rune(t); len(rs) > 120 {
		t = string(rs[:120])
	}
	t = strings.TrimRight(strings.TrimSpace(t), ".")
	if t == "" || t == "." || t == "-" {
		t = "Printed " + now.Format("2006-01-02 150405")
	}
	return t + ".pdf"
}

// saveStartDir: last folder used in the dialog, else the configured output
// folder, else Documents/Verae Timestamps (created so the dialog opens there).
func saveStartDir(outDir string) string {
	for _, d := range []string{settings.LastSaveDir(), outDir} {
		if d == "" {
			continue
		}
		if st, err := os.Stat(d); err == nil && st.IsDir() {
			return d
		}
	}
	d, err := job.DefaultOutDir()
	if err != nil {
		h, _ := os.UserHomeDir()
		return h
	}
	_ = os.MkdirAll(d, 0o755)
	return d
}

// askSaveTarget shows the native Save As dialog for a print job. It returns
// (path, true) when the user picked a file, ("", false) when they cancelled,
// and ("", true) when no dialog could be shown (the job is then stamped into
// the default folder as before, so a print is never lost to a dialog error).
func askSaveTarget(lj vlog.Job, title, outDir string) (string, bool) {
	name := saveNameFromTitle(title, time.Now())
	dir := saveStartDir(outDir)
	lj.Printf("saveas: prompting (default name %q, folder %q)", name, dir)
	p, ok, err := nativeSaveDialog(name, dir)
	if err != nil {
		lj.Errorf("saveas: dialog unavailable (%v); saving to default folder", err)
		return "", true
	}
	if !ok {
		return "", false
	}
	p = ensurePDFExt(p)
	_ = settings.SetLastSaveDir(filepath.Dir(p))
	lj.Printf("saveas: user chose %q", p)
	return p, true
}

// ensurePDFExt adds ".pdf" when the user typed a name without it. The dialog
// only confirmed replacing the name as typed, so if "<name>.pdf" exists we
// pick "<name>-2.pdf" etc. instead of overwriting it.
func ensurePDFExt(p string) string {
	if strings.EqualFold(filepath.Ext(p), ".pdf") {
		return p
	}
	base := p
	p = base + ".pdf"
	for i := 2; i < 1000; i++ {
		if _, err := os.Stat(p); os.IsNotExist(err) {
			break
		}
		p = fmt.Sprintf("%s-%d.pdf", base, i)
	}
	return p
}