package tpl

import (
	"html/template"
	"io/fs"
	"os"
	"path/filepath"
	"sync"
)

// Options for the template
type Options struct {
	BaseDir       string
	BasePath      string
	DynamicReload bool
	FuncMap       template.FuncMap
	Fsys          fs.FS
}

var cache = make(map[string]template.Template)
var cacheMutex = new(sync.RWMutex)

// Load new template
func Load(opts *Options) (*template.Template, error) {
	if !opts.DynamicReload {
		if tpl, ok := getCache(opts.BasePath); ok {
			return &tpl, nil
		}
	}
	tpl, err := readFiles(opts.BasePath, opts)
	if err != nil {
		return nil, err
	}
	if !opts.DynamicReload {
		setCache(opts.BasePath, *tpl)
	}
	return tpl, nil
}

func readFiles(basePath string, opts *Options) (*template.Template, error) {
	var (
		tpl   *template.Template
		err   error
		files []string
	)
	if !opts.DynamicReload {
		if err := fs.WalkDir(opts.Fsys, basePath, func(path string, d fs.DirEntry, err error) error {
			if !d.IsDir() {
				files = append(files, path)
			}
			return nil
		}); err != nil {
			return nil, err
		}
		tpl, err = template.New(opts.BaseDir).
			Funcs(FuncMap()).
			Funcs(opts.FuncMap).
			ParseFS(opts.Fsys, files...)
		if err != nil {
			return nil, err
		}
	} else {
		if err := filepath.Walk(basePath, func(path string, info os.FileInfo, err error) error {
			if !info.IsDir() {
				files = append(files, path)
			}
			return nil
		}); err != nil {
			return nil, err
		}
		tpl, err = template.New(opts.BaseDir).
			Funcs(FuncMap()).
			Funcs(opts.FuncMap).
			ParseFiles(files...)
		if err != nil {
			return nil, err
		}
	}
	return tpl, nil
}