package ui

import (
	"fmt"
	"image"
	_ "image/gif"
	_ "image/jpeg"
	_ "image/png"
	"os"

	"gioui.org/layout"
	"gioui.org/unit"
	"gioui.org/widget"
	"gioui.org/widget/material"

	"git.wxccs.org/iceking2nd/winauth-go/internal/authenticator"
	"git.wxccs.org/iceking2nd/winauth-go/internal/global"
	"git.wxccs.org/iceking2nd/winauth-go/internal/i18n"
	"git.wxccs.org/iceking2nd/winauth-go/internal/qr"
	"git.wxccs.org/iceking2nd/winauth-go/internal/win32"
)

// scanQRDialog drives the "scan otpauth:// QR code" flow. It offers two
// entry points: read a PNG/JPG file from disk, or grab whatever image
// is currently on the clipboard (Win+Shift+S screenshot landing zone).
// On success the dialog hands the caller a fully built authenticator
// and a default display name derived from the QR's issuer + label.
type scanQRDialog struct {
	pathEd     widget.Editor
	fromFileBt widget.Clickable
	clipBt     widget.Clickable
	cancelBt   widget.Clickable

	errorMsg string
}

func newScanQRDialog() *scanQRDialog {
	d := &scanQRDialog{}
	d.pathEd.SingleLine = true
	return d
}

// Layout follows the same Dialog contract as the per-vendor add
// dialogs: onDone(nil, "") on cancel, onDone(auth, displayName) on
// successful scan + parse.
func (d *scanQRDialog) Layout(
	gtx layout.Context, th *material.Theme,
	onDone func(authenticator.Authenticator, string),
) layout.Dimensions {
	if d.cancelBt.Clicked(gtx) {
		onDone(nil, "")
		return layout.Dimensions{Size: gtx.Constraints.Max}
	}
	if d.fromFileBt.Clicked(gtx) {
		path := d.pathEd.Text()
		if path == "" {
			d.errorMsg = i18n.T("msg_empty_qr_path")
		} else if auth, name, err := decodeFromFile(path); err != nil {
			d.errorMsg = fmt.Sprintf(i18n.T("msg_qr_failed"), err.Error())
			global.Log.WithField("func", "internal.ui.scanQRDialog.fromFile").
				WithError(err).Warn("QR scan from file failed")
		} else {
			onDone(auth, name)
			return layout.Dimensions{Size: gtx.Constraints.Max}
		}
	}
	if d.clipBt.Clicked(gtx) {
		if auth, name, err := decodeFromClipboard(); err != nil {
			d.errorMsg = fmt.Sprintf(i18n.T("msg_qr_failed"), err.Error())
			global.Log.WithField("func", "internal.ui.scanQRDialog.fromClipboard").
				WithError(err).Warn("QR scan from clipboard failed")
		} else {
			onDone(auth, name)
			return layout.Dimensions{Size: gtx.Constraints.Max}
		}
	}

	body := func(gtx layout.Context) layout.Dimensions {
		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
			layout.Rigid(material.Body2(th, i18n.T("qr_intro")).Layout),
			layout.Rigid(layout.Spacer{Height: unit.Dp(8)}.Layout),
			layout.Rigid(labeledEditor(th, i18n.T("label_qr_path"), &d.pathEd, "C:\\...\\code.png")),
			layout.Rigid(func(gtx layout.Context) layout.Dimensions {
				return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
					layout.Rigid(material.Button(th, &d.fromFileBt, i18n.T("btn_qr_from_file")).Layout),
					layout.Rigid(layout.Spacer{Width: unit.Dp(8)}.Layout),
					layout.Rigid(material.Button(th, &d.clipBt, i18n.T("btn_qr_from_clipboard")).Layout),
				)
			}),
			layout.Rigid(errorLabel(th, d.errorMsg)),
		)
	}

	// Use modalCard with only the cancel button (OK is a no-op here
	// because the action buttons live inside the body).
	return modalCardCancel(gtx, th, i18n.T("dialog_scan_qr_title"),
		i18n.T("btn_cancel"), &d.cancelBt, body)
}

// decodeFromFile reads a PNG/JPG/GIF off disk, decodes any QR code in
// it, parses the otpauth URI, then builds the matching authenticator.
func decodeFromFile(path string) (authenticator.Authenticator, string, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, "", err
	}
	defer f.Close()
	img, _, err := image.Decode(f)
	if err != nil {
		return nil, "", fmt.Errorf("decode image: %w", err)
	}
	return decodeAndBuild(img)
}

// decodeFromClipboard pulls the current clipboard image (Snipping Tool
// landing zone) and runs the same pipeline.
func decodeFromClipboard() (authenticator.Authenticator, string, error) {
	img, err := win32.GetClipboardImage()
	if err != nil {
		return nil, "", err
	}
	if img == nil {
		return nil, "", fmt.Errorf("%s", i18n.T("msg_clipboard_no_image"))
	}
	return decodeAndBuild(img)
}

func decodeAndBuild(img image.Image) (authenticator.Authenticator, string, error) {
	text, err := qr.DecodeImage(img)
	if err != nil {
		return nil, "", err
	}
	parsed, err := qr.ParseOtpAuth(text)
	if err != nil {
		return nil, "", err
	}
	auth, err := authenticatorFromOtpAuth(parsed)
	if err != nil {
		return nil, "", err
	}
	return auth, displayNameFromOtpAuth(parsed), nil
}

func authenticatorFromOtpAuth(p *qr.OtpAuth) (authenticator.Authenticator, error) {
	switch p.Type {
	case "totp":
		a := authenticator.NewGoogleAuthenticator()
		if err := a.Enroll(p.SecretBase32); err != nil {
			return nil, err
		}
		if p.Digits > 0 {
			a.CodeDigits = p.Digits
		}
		if p.Period > 0 {
			a.Period = p.Period
		}
		return a, nil
	case "hotp":
		a := authenticator.NewHOTPAuthenticator()
		if err := a.Enroll(p.SecretBase32, p.Counter); err != nil {
			return nil, err
		}
		if p.Digits > 0 {
			a.CodeDigits = p.Digits
		}
		return a, nil
	default:
		return nil, fmt.Errorf("unsupported otpauth type %q", p.Type)
	}
}

func displayNameFromOtpAuth(p *qr.OtpAuth) string {
	if p.Issuer != "" && p.Label != "" {
		return p.Issuer + ": " + p.Label
	}
	if p.Label != "" {
		return p.Label
	}
	if p.Issuer != "" {
		return p.Issuer
	}
	return "QR"
}