ferro_theme/
loader.rs

1use std::path::Path;
2
3use crate::error::ThemeError;
4use crate::template::ThemeTemplates;
5
6const DEFAULT_THEME_CSS: &str = include_str!("../assets/default.css");
7
8/// A loaded theme: CSS tokens and optional intent template overrides.
9///
10/// Two construction paths:
11/// - [`Theme::default_theme()`] — always available, embedded at compile time.
12/// - [`Theme::from_path()`] — loads from a filesystem directory.
13#[derive(Debug, Clone)]
14pub struct Theme {
15    /// CSS content as plain CSS variable declarations (`:root { ... }`).
16    pub css: String,
17
18    /// Optional intent template overrides; all-`None` means built-in layouts apply.
19    pub templates: ThemeTemplates,
20}
21
22impl Theme {
23    /// Returns the embedded default theme.
24    ///
25    /// The CSS contains plain `:root { ... }` CSS variable declarations for all 23
26    /// semantic token slots (light and dark modes). Safe to inject into a `<style>` tag
27    /// without Tailwind processing.
28    /// Templates are all-`None` — built-in intent layouts apply unchanged.
29    pub fn default_theme() -> Self {
30        Self {
31            css: DEFAULT_THEME_CSS.to_string(),
32            templates: ThemeTemplates::default(),
33        }
34    }
35
36    /// Loads a theme from a directory on the filesystem.
37    ///
38    /// Expects `tokens.css` to exist in the directory.
39    /// `theme.json` is optional — if absent, templates default to empty (`ThemeTemplates::default()`).
40    ///
41    /// # Errors
42    ///
43    /// - [`ThemeError::NotFound`] — directory does not exist.
44    /// - [`ThemeError::Io`] — `tokens.css` cannot be read.
45    /// - [`ThemeError::Json`] — `theme.json` exists but cannot be parsed.
46    pub fn from_path(path: &str) -> Result<Self, ThemeError> {
47        let dir = Path::new(path);
48        if !dir.exists() {
49            return Err(ThemeError::NotFound(path.to_string()));
50        }
51
52        let css_path = dir.join("tokens.css");
53        let css = std::fs::read_to_string(css_path)?;
54
55        let templates_path = dir.join("theme.json");
56        let templates = if templates_path.exists() {
57            let json = std::fs::read_to_string(&templates_path)?;
58            serde_json::from_str(&json)?
59        } else {
60            ThemeTemplates::default()
61        };
62
63        Ok(Self { css, templates })
64    }
65}
66
67#[cfg(test)]
68mod tests {
69    use super::*;
70
71    #[test]
72    fn default_theme_returns_non_empty_css_with_color_primary() {
73        let theme = Theme::default_theme();
74        assert!(!theme.css.is_empty());
75        assert!(theme.css.contains("--color-primary"));
76    }
77
78    #[test]
79    fn default_theme_returns_all_none_templates() {
80        let theme = Theme::default_theme();
81        assert!(theme.templates.browse.is_none());
82        assert!(theme.templates.focus.is_none());
83        assert!(theme.templates.collect.is_none());
84        assert!(theme.templates.process.is_none());
85        assert!(theme.templates.summarize.is_none());
86        assert!(theme.templates.analyze.is_none());
87        assert!(theme.templates.track.is_none());
88    }
89
90    #[test]
91    fn from_path_loads_tokens_css_and_theme_json() {
92        let dir = tempfile::tempdir().unwrap();
93        let css_content = "@theme { --color-primary: oklch(55% 0.2 250); }";
94        let json_content = r#"{"browse": {"display": {"slots": ["title", "fields"]}}}"#;
95        std::fs::write(dir.path().join("tokens.css"), css_content).unwrap();
96        std::fs::write(dir.path().join("theme.json"), json_content).unwrap();
97
98        let theme = Theme::from_path(dir.path().to_str().unwrap()).unwrap();
99        assert_eq!(theme.css, css_content);
100        assert!(theme.templates.browse.is_some());
101        let browse = theme.templates.browse.unwrap();
102        assert_eq!(browse.display.slots, vec!["title", "fields"]);
103    }
104
105    #[test]
106    fn from_path_works_without_theme_json() {
107        let dir = tempfile::tempdir().unwrap();
108        let css_content = "@theme { --color-primary: oklch(55% 0.2 250); }";
109        std::fs::write(dir.path().join("tokens.css"), css_content).unwrap();
110
111        let theme = Theme::from_path(dir.path().to_str().unwrap()).unwrap();
112        assert_eq!(theme.css, css_content);
113        assert!(theme.templates.browse.is_none());
114    }
115
116    #[test]
117    fn from_path_returns_not_found_for_nonexistent_directory() {
118        let result = Theme::from_path("/nonexistent/path/that/does/not/exist");
119        assert!(matches!(result, Err(ThemeError::NotFound(_))));
120    }
121
122    #[test]
123    fn from_path_returns_json_error_for_invalid_theme_json() {
124        let dir = tempfile::tempdir().unwrap();
125        std::fs::write(dir.path().join("tokens.css"), "@theme {}").unwrap();
126        std::fs::write(dir.path().join("theme.json"), "not valid json{{").unwrap();
127
128        let result = Theme::from_path(dir.path().to_str().unwrap());
129        assert!(matches!(result, Err(ThemeError::Json(_))));
130    }
131
132    #[test]
133    fn from_path_returns_io_error_when_tokens_css_missing() {
134        let dir = tempfile::tempdir().unwrap();
135        // Only create theme.json, not tokens.css
136        std::fs::write(dir.path().join("theme.json"), "{}").unwrap();
137
138        let result = Theme::from_path(dir.path().to_str().unwrap());
139        assert!(matches!(result, Err(ThemeError::Io(_))));
140    }
141}
ferro_theme/loader.rs

ferro_theme/
loader.rs
