// Package view handles WebUI generation for clustvirt. The methods and utilties in this module control what is viewed,
// templates that are loaded, and building those templates. Caching is not considered beyond what is done
// automattically by go (if anything).
package view

import (
	"html/template"
	"io"
	"log"
	"os"
)

// View is responsible for assembling a group of templates, providing
// methods to add data and compose pages in a common way.
type View struct {
	content  string
	template *template.Template
}

var basetemplate *template.Template

// New returns a new instance of the View, expecting the content to be the actual
// content as a template defining "content", in string format.
func New(content string) *View {
	if basetemplate == nil {
		log.Println("Initializing base template")
		basetemplate = template.Must(template.New("").ParseFiles(index, header, footer))
	}
	log.Println("Cloning base template")
	v := &View{template: template.Must(basetemplate.Clone())}
	v.parse(content)

	return v
}

// NewFromFile loads a template from a file
func NewFromFile(file string) (*View, error) {
	b, err := os.ReadFile(file)
	return New(string(b)), err
}

func (v *View) parse(tmpl string) error {
	log.Println("Parsing template contents")
	if _, err := v.template.Parse(tmpl); err != nil {
		return err
	}
	log.Println("Template parsed")
	return nil
}

// Render returns the executed template with data
func (v *View) Render(w io.Writer, data any) error {
	log.Println("Excuting template")
	return v.template.ExecuteTemplate(w, "_index", data)
}