package render

import (
	"context"
	"net/http"

	"github.com/a-h/templ"
	templruntime "github.com/a-h/templ/runtime"

	"git.ma-al.com/goc_marek/ps_shop/internal/assets"
	"git.ma-al.com/goc_marek/ps_shop/internal/viewmodel"
	"git.ma-al.com/goc_marek/ps_shop/templates"
)

func init() {
	// Minimize templ's internal buffering so HTML reaches the client as it is rendered.
	templruntime.DefaultBufferSize = 1
}

type Engine struct {
	assets assets.Manifest
}

func New(manifest assets.Manifest) *Engine {
	return &Engine{assets: manifest}
}

func (e *Engine) Product(w http.ResponseWriter, r *http.Request, data viewmodel.ProductPageData) error {
	startHTMLStream(w)
	component := templates.ProductPage(data, e.assets.CSSPath("app.css"), e.assets.JSPath("app.js"))
	return streamComponent(r.Context(), w, component)
}

func (e *Engine) Category(w http.ResponseWriter, r *http.Request, data viewmodel.CategoryPageData) error {
	startHTMLStream(w)
	component := templates.CategoryPage(data, e.assets.CSSPath("app.css"), e.assets.JSPath("app.js"))
	return streamComponent(r.Context(), w, component)
}

func startHTMLStream(w http.ResponseWriter) {
	if w == nil {
		return
	}
	headers := w.Header()
	if headers.Get("Content-Type") == "" {
		headers.Set("Content-Type", "text/html; charset=utf-8")
	}
	w.WriteHeader(http.StatusOK)
	if flusher, ok := w.(http.Flusher); ok {
		flusher.Flush()
	}
}

func streamComponent(ctx context.Context, w http.ResponseWriter, component templ.Component) error {
	if component == nil {
		return nil
	}
	var buffer templruntime.Buffer
	buffer.Reset(w)
	if err := component.Render(ctx, &buffer); err != nil {
		return err
	}
	return buffer.Flush()
}