// Package html renders an internal.AggregatorWriter as a complete,
// standalone HTML document built around the same table fragment produced by
// table.Printer.RenderHTML. The document includes the Bootstrap 5.3
// stylesheet via CDN and embeds the raw table fragment without HTML-escaping
// it so the result opens directly in a browser.
package html

import (
	_ "embed"
	"fmt"
	"html/template"
	"io"
	"time"

	"github.com/nmoniz/any2anexoj/internal"
	"github.com/nmoniz/any2anexoj/internal/writing/table"
)

// translator is the contract the HTML writer relies on for localized
// document text such as the page title. *writing.Localizer satisfies it.
type translator interface {
	Translate(key string, count int, values map[string]any) string
}

// bootstrapCSSURL is the jsDelivr CDN URL for Bootstrap 5.3.3.
const bootstrapCSSURL = "https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css"

// bootstrapIntegrity is the official SRI hash for Bootstrap 5.3.3 css.
const bootstrapIntegrity = "sha384-QWTKZyjpPEjISv5WaRU9OFeRpok6YctnYmDr5pNlyT2bRjXh0JMhjY6hW+ALEwIH"

// Writer writes a complete HTML document for an AggregatorWriter.
type Writer struct {
	output     io.Writer
	printer    *table.Printer
	translator translator
	lang       string
}

// NewWriter builds a Writer that writes a complete HTML document to
// w. The printer is used purely as a source for the raw <table> fragment via
// RenderHTML; this writer never invokes Render or any method that writes to
// printer's own io.Writer. The document title is looked up from the
// "report_title" translation via tr, so callers never pass a pre-baked title.
func NewWriter(w io.Writer, printer *table.Printer, tr translator, lang string) *Writer {
	return &Writer{
		output:     w,
		printer:    printer,
		translator: tr,
		lang:       lang,
	}
}

//go:embed document.tmpl
var documentTemplateBody string

// documentTemplate renders the full HTML page from document.tmpl. The table
// fragment is typed as template.HTML so the template engine emits it
// verbatim without escaping the angle brackets in the <table> markup.
var documentTemplate = template.Must(template.New("html").Parse(documentTemplateBody))

// Render writes a complete standalone HTML document for aw to the configured
// output. The same Writer may be reused; each call rebuilds the table
// fragment from aw so the rendered <tr> count reflects aw's current items and
// no rows are duplicated across invocations.
func (hw *Writer) Render(aw *internal.AggregatorWriter) error {
	if hw.printer == nil {
		return fmt.Errorf("html: nil printer")
	}
	fragment := hw.printer.RenderHTML(aw)
	title := hw.translator.Translate("report_title", 1, nil)
	data := struct {
		Lang          string
		Title         string
		CSSURL        string
		Integrity     string
		TableFragment template.HTML
		GeneratedAt   string
	}{
		Lang:          hw.lang,
		Title:         title,
		CSSURL:        bootstrapCSSURL,
		Integrity:     bootstrapIntegrity,
		TableFragment: template.HTML(fragment),
		GeneratedAt:   time.Now().UTC().Format(time.RFC3339),
	}
	if err := documentTemplate.Execute(hw.output, data); err != nil {
		return fmt.Errorf("render html document: %w", err)
	}
	return nil
}