package web

import (
	"fmt"
	"html/template"
	"net/http"

	"inventree/internal/assets"
	"inventree/internal/models"
)

// LabelTemplate describes a sheet of adhesive labels: cell size, grid, and
// page margins, all in inches, used to lay out printable asset tags.
type LabelTemplate struct {
	Key           string
	DisplayName   string
	LabelWidthIn  float64
	LabelHeightIn float64
	Cols          int
	Rows          int
	MarginTopIn   float64
	MarginLeftIn  float64
	ColGapIn      float64
	RowGapIn      float64
	QRSizeIn      float64
	// Approximate is true for templates whose margins/grid aren't from a
	// verified manufacturer spec sheet - print one test page on plain
	// paper and hold it up to a real label sheet before committing a
	// full (often expensive/waterproof) sheet to the printer.
	Approximate bool
}

var labelTemplates = map[string]LabelTemplate{
	"5160": {
		Key: "5160", DisplayName: `Avery 5160 - 1" x 2-5/8" (30/sheet)`,
		LabelWidthIn: 2.625, LabelHeightIn: 1, Cols: 3, Rows: 10,
		MarginTopIn: 0.5, MarginLeftIn: 0.1875, ColGapIn: 0.125, RowGapIn: 0,
		QRSizeIn: 0.85,
	},
	"61526": {
		Key: "61526", DisplayName: `Asset Tag Labels 61526 - 3/4" x 2" (~48/sheet)`,
		LabelWidthIn: 2, LabelHeightIn: 0.75, Cols: 4, Rows: 12,
		MarginTopIn: 1, MarginLeftIn: 0.25, ColGapIn: 0, RowGapIn: 0,
		QRSizeIn: 0.62, Approximate: true,
	},
}

const defaultLabelTemplate = "5160"

func (t LabelTemplate) css() template.CSS {
	return template.CSS(fmt.Sprintf(`
.label-sheet {
  width: 8.5in;
  box-sizing: border-box;
  padding: %.4fin %.4fin;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(%d, %.4fin);
  column-gap: %.4fin;
  row-gap: %.4fin;
  justify-content: center;
}
.label {
  width: %.4fin;
  height: %.4fin;
  box-sizing: border-box;
  padding: 0.06in 0.08in;
  display: flex;
  align-items: center;
  gap: 0.08in;
  overflow: hidden;
  page-break-inside: avoid;
}
.label img { width: %.4fin; height: %.4fin; flex-shrink: 0; }
`,
		t.MarginTopIn, t.MarginLeftIn, t.Cols, t.LabelWidthIn, t.ColGapIn, t.RowGapIn,
		t.LabelWidthIn, t.LabelHeightIn, t.QRSizeIn, t.QRSizeIn))
}

type labelItem struct {
	Asset models.Asset
	// template.URL marks this as pre-vetted safe (it's server-generated,
	// never user input), so html/template's URL filter doesn't replace it
	// with the "#ZgotmplZ" safety placeholder the way it would a plain
	// string containing a data: URI.
	QRData template.URL
}

type labelsPageData struct {
	User         *models.User
	Labels       []labelItem
	SheetCSS     template.CSS
	Templates    map[string]LabelTemplate
	TemplateKeys []string
	Selected     LabelTemplate
	AssetID      string
	FolderID     string
	Recursive    bool
}

// handleLabelsPage renders a print-ready sheet of QR-coded asset labels:
// either a single asset (?asset_id=) or every asset in a folder
// (?folder_id=&recursive=1), or the whole inventory with neither param.
// Each QR code encodes an absolute /scan/<tag> URL so a phone camera (or a
// USB barcode scanner focused on a browser address bar) opens straight to
// that asset.
func (a *App) handleLabelsPage(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	origin := requestOrigin(r)

	tmpl, ok := labelTemplates[r.URL.Query().Get("template")]
	if !ok {
		tmpl = labelTemplates[defaultLabelTemplate]
	}

	var list []models.Asset
	assetIDParam := r.URL.Query().Get("asset_id")
	folderIDParam := r.URL.Query().Get("folder_id")
	recursive := r.URL.Query().Get("recursive") == "1"

	if assetID, err := queryOptionalID(r, "asset_id"); err == nil && assetID != nil {
		asset, err := a.Assets.Get(ctx, *assetID)
		if err != nil {
			writeErr(w, http.StatusNotFound, err.Error())
			return
		}
		list = []models.Asset{*asset}
	} else {
		filter := assets.ListFilter{Page: 1, PageSize: 2000}
		if folderID, err := queryOptionalID(r, "folder_id"); err == nil && folderID != nil {
			filter.FolderID = folderID
			filter.FolderSet = true
			filter.IncludeSub = recursive
		}
		batch, _, err := a.Assets.List(ctx, filter)
		if err != nil {
			writeErr(w, http.StatusInternalServerError, err.Error())
			return
		}
		list = batch
	}

	labels := make([]labelItem, 0, len(list))
	for _, as := range list {
		qr, err := qrDataURI(origin+"/scan/"+as.AssetTag, 220)
		if err != nil {
			writeErr(w, http.StatusInternalServerError, err.Error())
			return
		}
		labels = append(labels, labelItem{Asset: as, QRData: template.URL(qr)})
	}

	a.Render(w, http.StatusOK, "labels", labelsPageData{
		User: currentUser(r), Labels: labels, SheetCSS: tmpl.css(),
		Templates: labelTemplates, TemplateKeys: []string{"5160", "61526"},
		Selected: tmpl, AssetID: assetIDParam, FolderID: folderIDParam, Recursive: recursive,
	})
}