go-blocks/templates.go

package goblocks

import (
	"bytes"
	"errors"
	"html/template"
	"log/slog"
	"maps"
	"net/http"
	"path/filepath"
	"reflect"
	"strconv"
	"strings"
	"time"
)

type (
	templateCache map[string]*template.Template

	TemplateData struct {
		Data  map[string]any
		Pages Pages
	}

	RenderOptions func(*Render)
	Render        struct {
		EnableCache   bool
		TemplatesPath string
		Functions     template.FuncMap
		TemplateData  TemplateData
		templateCache templateCache
	}
)

func defaultHTMLRender() *Render {
	return &Render{
		EnableCache:   false,
		TemplatesPath: "templates",
		TemplateData:  TemplateData{},
		Functions: template.FuncMap{
			"default": defaultIfEmpty,
			"dict":    Dict,
		},
		templateCache: templateCache{},
	}
}

func NewHTMLRender(opts ...RenderOptions) *Render {
	config := defaultHTMLRender()
	return config.apply(opts...)
}

func (re *Render) apply(opts ...RenderOptions) *Render {
	for _, opt := range opts {
		if opt != nil {
			opt(re)
		}
	}
	return re
}

func defaultIfEmpty(fallback string, value any) string {
	str, ok := value.(string)
	if !ok || strings.TrimSpace(str) == "" {
		return fallback
	}

	return str
}

func cloneFuncMap(src template.FuncMap) template.FuncMap {
	c := make(template.FuncMap)
	maps.Copy(c, src)
	return c
}

func (re *Render) Template(w http.ResponseWriter, layoutName, pageName string, td *TemplateData) error {
	if td == nil {
		td = &TemplateData{}
	}

	tmpl, err := re.loadTemplateWithLayout(layoutName, pageName)
	if err != nil {
		return err
	}

	buf := new(bytes.Buffer)
	if err = tmpl.ExecuteTemplate(buf, strings.TrimSuffix(layoutName, ".gohtml"), td); err != nil {
		return err
	}

	_, err = buf.WriteTo(w)
	return err
}

func (re *Render) RenderComponent(name string, td *TemplateData) (string, error) {
	if td == nil {
		td = &TemplateData{}
	}

	path := filepath.Join(re.TemplatesPath, "components", name)

	files := []string{path}
	matches, err := filepath.Glob(filepath.Join(re.TemplatesPath, "components", "*.gohtml"))
	if err != nil {
		return "", err
	}
	files = append(files, matches...)

	funcs := cloneFuncMap(re.Functions)
	tmpl, err := template.New(name).Funcs(funcs).ParseFiles(files...)
	if err != nil {
		return "", err
	}

	var buf bytes.Buffer
	err = tmpl.ExecuteTemplate(&buf, strings.TrimSuffix(name, ".gohtml"), td)
	return buf.String(), err
}

func (re *Render) loadTemplateWithLayout(layoutName, pageName string) (*template.Template, error) {
	cacheKey := layoutName + "::" + pageName

	if re.EnableCache {
		if tmpl, ok := re.templateCache[cacheKey]; ok {
			return tmpl, nil
		}
	}

	layoutPath := filepath.Join(re.TemplatesPath, "layouts", layoutName)
	pagePath := filepath.Join(re.TemplatesPath, "pages", pageName)

	files := []string{layoutPath, pagePath}
	componentFiles, err := filepath.Glob(filepath.Join(re.TemplatesPath, "components", "*.gohtml"))
	if err != nil {
		return nil, err
	}
	files = append(files, componentFiles...)

	funcs := cloneFuncMap(re.Functions)
	tmpl, err := template.New(layoutName).Funcs(funcs).ParseFiles(files...)
	if err != nil {
		return nil, err
	}

	if re.EnableCache {
		re.templateCache[cacheKey] = tmpl
		slog.Debug("template cached", "key", cacheKey)
	}

	return tmpl, nil
}

// Pages contains pagination info.
type Pages struct {
	// TotalElements indicates the total number of elements available for
	// pagination.
	TotalElements int
	// ElementsPerPage defines the number of elements to display per page in
	// pagination.
	ElementsPerPage int
	// ActualPage represents the current page number in pagination.
	ActualPage int
}

func (p *Pages) PaginationParams(r *http.Request) {
	limit := r.FormValue("limit")
	page := r.FormValue("page")

	if limit == "" {
		if p.ElementsPerPage != 0 {
			limit = strconv.Itoa(p.ElementsPerPage)
		} else {
			limit = "20"
		}
	}

	if page == "" || page == "0" {
		if p.ActualPage != 0 {
			page = strconv.Itoa(p.ActualPage)
		} else {
			page = "1"
		}
	}

	limitInt, _ := strconv.Atoi(limit)
	pageInt, _ := strconv.Atoi(page)
	offset := (pageInt - 1) * limitInt
	currentPage := offset/limitInt + 1

	p.ElementsPerPage = limitInt
	p.ActualPage = currentPage
}

func (p Pages) PaginateArray(elements any) any {
	itemsValue := reflect.ValueOf(elements)

	if p.ActualPage < 1 {
		p.ActualPage = 1
	}

	if p.ActualPage > p.TotalPages() {
		p.ActualPage = p.TotalPages()
	}

	startIndex := (p.ActualPage - 1) * p.ElementsPerPage
	endIndex := startIndex + p.ElementsPerPage

	return itemsValue.Slice(startIndex, endIndex).Interface()
}

func (p Pages) CurrentPage() int {
	return p.ActualPage
}

func (p Pages) TotalPages() int {
	return (p.TotalElements + p.ElementsPerPage - 1) / p.ElementsPerPage
}

func (p Pages) IsFirst() bool {
	return p.ActualPage == 1
}

func (p Pages) IsLast() bool {
	return p.ActualPage == p.TotalPages()
}

func (p Pages) HasPrevious() bool {
	return p.ActualPage > 1
}

func (p Pages) HasNext() bool {
	return p.ActualPage < p.TotalPages()
}

func (p Pages) Previous() int {
	if p.ActualPage > p.TotalPages() {
		return p.TotalPages()
	}
	return p.ActualPage - 1
}

func (p Pages) Next() int {
	if p.ActualPage < 1 {
		return 1
	}
	return p.ActualPage + 1
}

func (p Pages) GoToPage(page int) int {
	if page < 1 {
		page = 1
	} else if page > p.TotalPages() {
		page = p.TotalPages()
	}
	return page
}

func (p Pages) First() int {
	return p.GoToPage(1)
}

func (p Pages) Last() int {
	return p.GoToPage(p.TotalPages())
}

// Page contiene la información de una página. Utilizado para la barra de
// paginación que suelen mostrarse en la parte inferior de una lista o tabla.

// Page represents a single page in pagination, including its number and active
// state. Useful for pagination bar.
type Page struct {
	// Number is the numeric identifier of the page in pagination.
	Number int
	// Active indicates if the page is the currently selected page.
	Active bool
}

func (p Page) NumberOfPage() int {
	return p.Number
}

func (p Page) IsActive() bool {
	return p.Active
}

// PageRange generates a slice of Page instances representing a range of pages
// to be displayed in a pagination bar.
func (p Pages) PageRange(maxPagesToShow int) []Page {
	var pages []Page
	totalPages := p.TotalPages()

	startPage := p.ActualPage - (maxPagesToShow / 2)
	endPage := p.ActualPage + (maxPagesToShow / 2)

	if startPage < 1 {
		startPage = 1
		endPage = maxPagesToShow
	}

	if endPage > totalPages {
		endPage = totalPages
		startPage = totalPages - maxPagesToShow + 1
		if startPage < 1 {
			startPage = 1
		}
	}

	for i := startPage; i <= endPage; i++ {
		pages = append(pages, Page{
			Number: i,
			Active: i == p.ActualPage,
		})
	}

	return pages
}

func Dict(values ...any) (map[string]any, error) {
	if len(values)%2 != 0 {
		return nil, errors.New("invalid dict call")
	}
	dict := make(map[string]any, len(values)/2)
	for i := 0; i < len(values); i += 2 {
		key, ok := values[i].(string)
		if !ok {
			return nil, errors.New("dict keys must be strings")
		}
		dict[key] = values[i+1]
	}
	return dict, nil
}

func FormatDateSpanish(date time.Time) string {
	months := []string{"enero", "febrero", "marzo", "abril", "mayo", "junio", "julio", "agosto", "septiembre", "octubre", "noviembre", "diciembre"}
	days := []string{"domingo", "lunes", "martes", "miércoles", "jueves", "viernes", "sábado"}

	dayName := days[date.Weekday()]
	day := date.Day()
	month := months[date.Month()-1]
	year := date.Year()

	return dayName + ", " + strconv.Itoa(day) + " de " + month + " de " + strconv.Itoa(year)
}