forgejo/models/theme/theme_meta.go

package theme

import (
	"bufio"
	"errors"
	"fmt"
	"io"
	"strings"

	"forgejo.org/modules/assetfs"
)

// The Theme struct represents the metadata of a theme. Most fields are allowed to be null / blank.
type Theme struct {
	// ID is the theme id, e.g., forgejo-dark
	ID          string
	// Name is the theme's readable name, e.g., Forgejo. Note that the scheme is excluded in favor of the Scheme property.
	Name        string
	// Family is the theme's family, e.g. Catppuccin.
	Family      string
	// Author is the theme's author. It may be an invididual, a group, or an entity.
	Author      string
	// Url is the URL to the theme's website, e.g. https://forgejo.org.
	Url         string
	// Description is the theme's short description.
	Description string
	// Scheme is the theme's color scheme. It must be either: dark, light, or auto.
	Scheme      string
	// Recommended means the theme is guaranteed to be bug-free, usually a first-party theme.
	Recommended    bool
}

// loadThemeMeta loads theme metadata from a file in a layered FS.
//
// Theme ID is expected to be prefilled. The metadata will be assigned to the passed `theme` object.
func loadThemeMeta(assetFs *assetfs.LayeredFS, filename string, theme *Theme) error {
	file, err := assetFs.Open("assets/css/" + filename)

	if err != nil {
		return fmt.Errorf("failed to open file: %w", err)
	}

	defer file.Close()

	kv, err := scanThemeForKeyValueMetaMap(file, theme.ID) // ID is expected to be prefilled

	if err != nil {
		return fmt.Errorf("error scanning theme for meta: %w", err)
	}

	theme.Name = kv["name"]
	theme.Family = kv["family"]
	theme.Author = kv["author"]
	theme.Url = kv["url"]
	theme.Description = kv["description"]
	theme.Scheme = strings.ToLower(kv["scheme"])
	theme.Recommended = kv["recommended"] == "yes"

	return nil
}

// scanThemeForKeyValueMetaMap finds raw key-value metadata in an open file.
func scanThemeForKeyValueMetaMap(file io.Reader, id string) (map[string]string, error) {
	var kv = make(map[string]string)

	scanner := bufio.NewScanner(file)
	ok := false

	// webpack adds headers
	for scanner.Scan() {
		if strings.TrimSpace(scanner.Text()) == "/* theme "+id {
			ok = true
			break
		}
	}

	if !ok {
		return nil, errors.New("theme has no meta")
	}

	for scanner.Scan() {
		line := scanner.Text()

		parts := strings.Fields(line)

		if len(parts) == 0 {
			continue
		}

		key := strings.ToLower(parts[0])

		if key == "*/" {
			break
		}

		if len(parts) == 1 {
			kv[key] = "yes"
		} else {
			kv[key] = strings.Join(parts[1:], " ")
		}
	}

	if err := scanner.Err(); err != nil {
		return nil, fmt.Errorf("scanner error: %w", err)
	}

	return kv, nil
}