// stolen from gofiber/template but simpler
package render

import (
	"fmt"
	"io"
	"io/fs"
	"path/filepath"
	"strings"

	"github.com/mailgun/raymond/v2"
)

var Renderer *renderer

func Render(out io.Writer, name string, bind map[string]any) error {
	return Renderer.Render(out, name, bind)
}

type renderer struct {
	templates map[string]*raymond.Template
}

const ext = ".hbs"

func Initialize(views fs.FS) {
	r := new(renderer)
	r.templates = make(map[string]*raymond.Template)
	r.registerHelpers()
	fs.WalkDir(views, ".", func(path string, d fs.DirEntry, err error) error {
		if err != nil || d.IsDir() {
			return err
		}
		name, hasExt := strings.CutSuffix(path, ext)
		if !hasExt {
			return nil
		}
		path = filepath.ToSlash(path)
		file, err := views.Open(path)
		if err != nil {
			return err
		}
		defer file.Close()
		buf, err := io.ReadAll(file)
		if err != nil {
			return err
		}
		tmpl, err := raymond.Parse(string(buf))
		if err != nil {
			return err
		}
		r.templates[name] = tmpl
		return nil
	})
	for j := range r.templates {
		for n, template := range r.templates {
			r.templates[j].RegisterPartialTemplate(n, template)
		}
	}
	Renderer = r
}

func (r *renderer) Render(out io.Writer, name string, bind map[string]any) error {
	tmpl := r.templates[name]
	if tmpl == nil {
		return fmt.Errorf("render: template %s does not exist", name)
	}
	parsed, err := tmpl.Exec(bind)
	if err != nil {
		return fmt.Errorf("render: %w", err)
	}
	if _, err = out.Write([]byte(parsed)); err != nil {
		return fmt.Errorf("render: %w", err)
	}
	return err
}