feat: Add custom theme files

README.md

@@ -19,6 +19,25 @@ want real colors). Resolved in this order:
 The config file's own location can be changed at build time too, with
 `meson configure -Dconfig_subpath=...`.
 
+### Custom themes
+
+Any `--theme=NAME` (or `DAF_THEME`, or config `theme=`) that isn't
+`dark`/`light`/`mono` is looked up as a file at
+`$XDG_CONFIG_HOME/daf/themes/NAME.conf` (or
+`~/.config/daf/themes/NAME.conf` — directory changeable at build time via
+`meson configure -Dtheme_dir_subpath=...`). It's `key=value` lines, each
+value a 256-color palette index as `fg` or `fg,bg`:
+
+```
+# ~/.config/daf/themes/mytheme.conf
+base=dark          # start from a built-in theme; defaults to dark
+selection=196,231   # override just the roles you want
+```
+
+Unset roles are inherited from `base`. Available roles: `normal`, `gutter`,
+`gutter_current` (the current line's line-number digit), `selection`,
+`search_match`, `status_bar`, `tilde`.
+
 ## Building
 
 Built with [Meson](https://mesonbuild.com/):

meson.build

@@ -14,6 +14,7 @@ add_project_arguments('-D_POSIX_C_SOURCE=200809L', language: 'c')
 add_project_arguments(
   '-DDAF_DEFAULT_THEME="' + get_option('default_theme') + '"',
   '-DDAF_CONFIG_SUBPATH="' + get_option('config_subpath') + '"',
+  '-DDAF_THEME_DIR_SUBPATH="' + get_option('theme_dir_subpath') + '"',
   language: 'c',
 )
 

meson_options.txt

@@ -12,3 +12,10 @@ option(
   value: 'daf/config',
   description: 'Path to the user config file, relative to $XDG_CONFIG_HOME (or $HOME/.config)',
 )
+
+option(
+  'theme_dir_subpath',
+  type: 'string',
+  value: 'daf/themes',
+  description: 'Directory of custom theme files (<name>.conf), relative to $XDG_CONFIG_HOME (or $HOME/.config)',
+)

src/main.c

@@ -37,7 +37,7 @@ static const theme_t *resolve_theme(const char *cli_theme_name)
         name = theme_build_default_name();
     }
 
-    const theme_t *theme = theme_find(name);
+    const theme_t *theme = theme_load(name);
     if (theme == NULL) {
         fprintf(stderr, "daf: unknown theme \"%s\", falling back to \"dark\"\n", name);
         theme = theme_find("dark");

src/theme.c

@@ -4,12 +4,20 @@
 
 #include "theme.h"
 
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
+#include "common.h"
+
 #ifndef DAF_DEFAULT_THEME
 #define DAF_DEFAULT_THEME "dark"
 #endif
 
+#ifndef DAF_THEME_DIR_SUBPATH
+#define DAF_THEME_DIR_SUBPATH "daf/themes"
+#endif
+
 static const theme_t k_theme_dark = {
     .name = "dark",
     .normal = "\x1b[38;5;253;48;5;234m",
@@ -64,3 +72,148 @@ const char *theme_build_default_name(void)
 {
     return DAF_DEFAULT_THEME;
 }
+
+const char *theme_dir_subpath(void)
+{
+    return DAF_THEME_DIR_SUBPATH;
+}
+
+static void build_theme_path(char *out, size_t out_size, const char *name)
+{
+    const char *xdg = getenv("XDG_CONFIG_HOME");
+    if (xdg != NULL && xdg[0] != '\0') {
+        snprintf(out, out_size, "%s/%s/%s.conf", xdg, DAF_THEME_DIR_SUBPATH, name);
+        return;
+    }
+
+    const char *home = getenv("HOME");
+    if (home != NULL && home[0] != '\0') {
+        snprintf(out, out_size, "%s/.config/%s/%s.conf", home, DAF_THEME_DIR_SUBPATH, name);
+        return;
+    }
+
+    out[0] = '\0';
+}
+
+static char *trim(char *s)
+{
+    while (*s == ' ' || *s == '\t') {
+        s++;
+    }
+    size_t len = strlen(s);
+    while (len > 0 &&
+           (s[len - 1] == ' ' || s[len - 1] == '\t' || s[len - 1] == '\n' || s[len - 1] == '\r')) {
+        s[--len] = '\0';
+    }
+    return s;
+}
+
+static char *build_sgr(const char *spec)
+{
+    int fg = -1;
+    int bg = -1;
+    sscanf(spec, "%d,%d", &fg, &bg);
+    if (fg < 0) {
+        return NULL;
+    }
+
+    char buf[64];
+    if (bg >= 0) {
+        snprintf(buf, sizeof(buf), "\x1b[38;5;%d;48;5;%dm", fg, bg);
+    } else {
+        snprintf(buf, sizeof(buf), "\x1b[38;5;%dm", fg);
+    }
+    return xstrdup(buf);
+}
+
+static void apply_role(theme_t *custom, const char *key, char *sgr)
+{
+    if (strcmp(key, "normal") == 0) {
+        custom->normal = sgr;
+    } else if (strcmp(key, "gutter") == 0) {
+        custom->gutter = sgr;
+    } else if (strcmp(key, "gutter_current") == 0) {
+        custom->gutter_current = sgr;
+    } else if (strcmp(key, "selection") == 0) {
+        custom->selection = sgr;
+    } else if (strcmp(key, "search_match") == 0) {
+        custom->search_match = sgr;
+    } else if (strcmp(key, "status_bar") == 0) {
+        custom->status_bar = sgr;
+    } else if (strcmp(key, "tilde") == 0) {
+        custom->tilde = sgr;
+    } else {
+        free(sgr);
+    }
+}
+
+const theme_t *theme_load(const char *name)
+{
+    const theme_t *builtin = theme_find(name);
+    if (builtin != NULL) {
+        return builtin;
+    }
+
+    char path[512];
+    build_theme_path(path, sizeof(path), name);
+    if (path[0] == '\0') {
+        return NULL;
+    }
+
+    FILE *fp = fopen(path, "r");
+    if (fp == NULL) {
+        return NULL;
+    }
+
+    const theme_t *base = &k_theme_dark;
+    char line[256];
+    while (fgets(line, sizeof(line), fp) != NULL) {
+        char *s = trim(line);
+        if (s[0] == '\0' || s[0] == '#') {
+            continue;
+        }
+        char *eq = strchr(s, '=');
+        if (eq == NULL) {
+            continue;
+        }
+        *eq = '\0';
+        char *key = trim(s);
+        char *value = trim(eq + 1);
+        if (strcmp(key, "base") == 0) {
+            const theme_t *found = theme_find(value);
+            if (found != NULL) {
+                base = found;
+            }
+        }
+    }
+
+    theme_t *custom = xmalloc(sizeof(theme_t));
+    *custom = *base;
+    custom->name = xstrdup(name);
+
+    rewind(fp);
+    while (fgets(line, sizeof(line), fp) != NULL) {
+        char *s = trim(line);
+        if (s[0] == '\0' || s[0] == '#') {
+            continue;
+        }
+        char *eq = strchr(s, '=');
+        if (eq == NULL) {
+            continue;
+        }
+        *eq = '\0';
+        char *key = trim(s);
+        char *value = trim(eq + 1);
+        if (strcmp(key, "base") == 0) {
+            continue;
+        }
+
+        char *sgr = build_sgr(value);
+        if (sgr != NULL) {
+            apply_role(custom, key, sgr);
+        }
+    }
+
+    fclose(fp);
+    return custom;
+}

src/theme.h

@@ -19,6 +19,10 @@ typedef struct {
 
 const theme_t *theme_find(const char *name);
 
+const theme_t *theme_load(const char *name);
+
 const char *theme_build_default_name(void);
 
+const char *theme_dir_subpath(void);
+
 #endif /* DAF_THEME_H */

tests/test_theme.c

@@ -3,11 +3,23 @@
  */
 
 #include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
 #include "theme.h"
 
-int main(void)
+static void write_file(const char *path, const char *content)
+{
+    FILE *fp = fopen(path, "w");
+    assert(fp != NULL);
+    fputs(content, fp);
+    fclose(fp);
+}
+
+static void test_builtin_themes(void)
 {
     const theme_t *dark = theme_find("dark");
     assert(dark != NULL);
@@ -28,6 +40,80 @@ int main(void)
 
     const char *default_name = theme_build_default_name();
     assert(theme_find(default_name) != NULL);
+}
+
+static void test_load_prefers_builtin(void)
+{
+    assert(theme_load("dark") == theme_find("dark"));
+}
+
+static void test_load_missing_returns_null(void)
+{
+    setenv("XDG_CONFIG_HOME", "/tmp/daf_theme_test_does_not_exist", 1);
+    assert(theme_load("no-such-custom-theme") == NULL);
+}
+
+static const char *setup_theme_dir(void)
+{
+    static char base[256];
+    snprintf(base, sizeof(base), "/tmp/daf_theme_test_%d", (int)getpid());
+    mkdir(base, 0700);
+
+    char subpath_copy[256];
+    snprintf(subpath_copy, sizeof(subpath_copy), "%s", theme_dir_subpath());
+
+    char path[600];
+    snprintf(path, sizeof(path), "%s", base);
 
+    char *segment = strtok(subpath_copy, "/");
+    while (segment != NULL) {
+        size_t len = strlen(path);
+        snprintf(path + len, sizeof(path) - len, "/%s", segment);
+        mkdir(path, 0700);
+        segment = strtok(NULL, "/");
+    }
+
+    setenv("XDG_CONFIG_HOME", base, 1);
+    return base;
+}
+
+static void test_load_custom_theme_with_base(void)
+{
+    const char *base = setup_theme_dir();
+    char path[700];
+    snprintf(path, sizeof(path), "%s/%s/mytheme.conf", base, theme_dir_subpath());
+    write_file(path, "# custom theme\nbase=light\nselection=196,231\n");
+
+    const theme_t *custom = theme_load("mytheme");
+    assert(custom != NULL);
+    assert(strcmp(custom->name, "mytheme") == 0);
+    assert(strcmp(custom->selection, "\x1b[38;5;196;48;5;231m") == 0);
+    /* Roles not overridden inherit from the requested base (light). */
+    const theme_t *light = theme_find("light");
+    assert(strcmp(custom->normal, light->normal) == 0);
+    assert(strcmp(custom->status_bar, light->status_bar) == 0);
+}
+
+static void test_load_custom_theme_defaults_to_dark_base(void)
+{
+    const char *base = setup_theme_dir();
+    char path[700];
+    snprintf(path, sizeof(path), "%s/%s/nobase.conf", base, theme_dir_subpath());
+    write_file(path, "tilde=250\n");
+
+    const theme_t *custom = theme_load("nobase");
+    assert(custom != NULL);
+    assert(strcmp(custom->tilde, "\x1b[38;5;250m") == 0);
+    const theme_t *dark = theme_find("dark");
+    assert(strcmp(custom->normal, dark->normal) == 0);
+}
+
+int main(void)
+{
+    test_builtin_themes();
+    test_load_prefers_builtin();
+    test_load_missing_returns_null();
+    test_load_custom_theme_with_base();
+    test_load_custom_theme_defaults_to_dark_base();
     return 0;
 }