package web

import (
	"errors"
	"fmt"
	"html/template"
	"strings"

	"tug/internal/transport/web/text"
)

type Ident string

const identMarker = "{ident}"

var errNoMarker = errors.New("catalog sentence has no identifier marker")

func identHTML(v Ident) template.HTML {
	return template.HTML(`<code class="ident">` + template.HTMLEscapeString(string(v)) + `</code>`)
}

func interpolate(sentence string, v Ident) (template.HTML, error) {
	before, after, ok := strings.Cut(sentence, identMarker)
	if !ok || strings.Contains(after, identMarker) {
		return "", errNoMarker
	}
	return template.HTML(template.HTMLEscapeString(before)) + identHTML(v) + template.HTML(template.HTMLEscapeString(after)), nil
}

func lookup(k text.Key) (string, error) {
	s, ok := text.Lookup(k)
	if !ok {
		return "", fmt.Errorf("unknown catalog key %q", k)
	}
	return s, nil
}

func translate(k text.Key, v Ident) (template.HTML, error) {
	s, err := lookup(k)
	if err != nil {
		return "", err
	}
	out, err := interpolate(s, v)
	if err != nil {
		return "", fmt.Errorf("%w: %q", err, k)
	}
	return out, nil
}

func translateText(k text.Key, v Ident) (string, error) {
	s, err := lookup(k)
	if err != nil {
		return "", err
	}
	before, after, ok := strings.Cut(s, identMarker)
	if !ok || strings.Contains(after, identMarker) {
		return "", fmt.Errorf("%w: %q", errNoMarker, k)
	}
	return before + string(v) + after, nil
}

func funcs() template.FuncMap {
	return template.FuncMap{
		"t":   lookup,
		"tr":  translate,
		"trt": translateText,
		"id":  identHTML,
	}
}