feat: Add color themes

README.md

@@ -4,9 +4,20 @@
 
 Daf (Hebrew `דף` — "sheet/page") is a simple console text editor written in C.
 
-## Planned Features
+## Themes
 
-Theming, and similar features are planned for future versions.
+Three built-in 256-color themes: `dark` (default), `light`, and `mono` (the
+original reverse-video/underline look, for terminals or tastes that don't
+want real colors). Resolved in this order:
+
+1. `--theme=NAME` on the command line
+2. the `DAF_THEME` environment variable
+3. `theme=NAME` in the config file (`$XDG_CONFIG_HOME/daf/config`, or
+   `~/.config/daf/config`) — `#` starts a comment
+4. the build-time default (`meson configure -Ddefault_theme=NAME`)
+
+The config file's own location can be changed at build time too, with
+`meson configure -Dconfig_subpath=...`.
 
 ## Building
 

meson.build

@@ -11,6 +11,11 @@ project(
 )
 
 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') + '"',
+  language: 'c',
+)
 
 subdir('src')
 subdir('tests')

meson_options.txt

@@ -0,0 +1,14 @@
+option(
+  'default_theme',
+  type: 'combo',
+  choices: ['dark', 'light', 'mono'],
+  value: 'dark',
+  description: 'Theme used when nothing else (flag, env var, config file) picks one',
+)
+
+option(
+  'config_subpath',
+  type: 'string',
+  value: 'daf/config',
+  description: 'Path to the user config file, relative to $XDG_CONFIG_HOME (or $HOME/.config)',
+)

src/config.c

@@ -0,0 +1,89 @@
+/* SPDX-FileCopyrightText: AnmiTaliDev <anmitalidev@nuros.org>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifndef DAF_CONFIG_SUBPATH
+#define DAF_CONFIG_SUBPATH "daf/config"
+#endif
+
+static void build_config_path(char *out, size_t out_size)
+{
+    const char *xdg = getenv("XDG_CONFIG_HOME");
+    if (xdg != NULL && xdg[0] != '\0') {
+        snprintf(out, out_size, "%s/%s", xdg, DAF_CONFIG_SUBPATH);
+        return;
+    }
+
+    const char *home = getenv("HOME");
+    if (home != NULL && home[0] != '\0') {
+        snprintf(out, out_size, "%s/.config/%s", home, DAF_CONFIG_SUBPATH);
+        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 void apply_line(daf_config_t *out, char *line)
+{
+    char *s = trim(line);
+    if (s[0] == '\0' || s[0] == '#') {
+        return;
+    }
+
+    char *eq = strchr(s, '=');
+    if (eq == NULL) {
+        return;
+    }
+    *eq = '\0';
+    char *key = trim(s);
+    char *value = trim(eq + 1);
+
+    if (strcmp(key, "theme") == 0) {
+        snprintf(out->theme_name, sizeof(out->theme_name), "%s", value);
+    }
+}
+
+void config_load(daf_config_t *out)
+{
+    char path[512];
+    build_config_path(path, sizeof(path));
+    if (path[0] == '\0') {
+        return;
+    }
+
+    FILE *fp = fopen(path, "r");
+    if (fp == NULL) {
+        return;
+    }
+
+    char line[256];
+    while (fgets(line, sizeof(line), fp) != NULL) {
+        apply_line(out, line);
+    }
+
+    fclose(fp);
+}
+
+const char *config_subpath(void)
+{
+    return DAF_CONFIG_SUBPATH;
+}

src/config.h

@@ -0,0 +1,21 @@
+/* SPDX-FileCopyrightText: AnmiTaliDev <anmitalidev@nuros.org>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#ifndef DAF_CONFIG_H
+#define DAF_CONFIG_H
+
+typedef struct {
+    char theme_name[64]; /* empty if the config file didn't set one */
+} daf_config_t;
+
+/* Reads the user config file (key=value lines, '#' comments) if it exists.
+ * `out` must be zero-initialized by the caller; a missing file, or one that
+ * doesn't set a given key, simply leaves the matching field untouched. */
+void config_load(daf_config_t *out);
+
+/* Path to the config file, relative to $XDG_CONFIG_HOME (or $HOME/.config),
+ * baked in at build time via `meson configure -Dconfig_subpath=...`. */
+const char *config_subpath(void);
+
+#endif /* DAF_CONFIG_H */

src/editor.c

@@ -209,6 +209,10 @@ void editor_init(editor_t *ed, int screen_rows, int screen_cols)
     ed->screen_cols = screen_cols;
     ed->mode = MODE_EDIT;
     ed->filetype = "Plain Text";
+    ed->theme = theme_find(theme_build_default_name());
+    if (ed->theme == NULL) {
+        ed->theme = theme_find("dark");
+    }
     editor_set_status(ed, "daf %s  |  Ctrl-S save  Ctrl-Q quit  Ctrl-F find  Ctrl-G go to line", DAF_VERSION);
 }
 

src/editor.h

@@ -10,6 +10,7 @@
 
 #include "buffer.h"
 #include "search.h"
+#include "theme.h"
 
 typedef enum {
     MODE_EDIT,
@@ -61,6 +62,7 @@ typedef struct {
 
     char status_msg[256];
     const char *filetype;
+    const theme_t *theme;
 
     edit_record_t *undo_stack;
     size_t undo_count;

src/main.c

@@ -4,26 +4,65 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
+#include "config.h"
 #include "editor.h"
 #include "input.h"
 #include "render.h"
 #include "terminal.h"
+#include "theme.h"
 
 static int text_rows_for(int terminal_rows)
 {
     int text_rows = terminal_rows - 2;
     return text_rows < 1 ? 1 : text_rows;
 }
 
+static const theme_t *resolve_theme(const char *cli_theme_name)
+{
+    daf_config_t config;
+    memset(&config, 0, sizeof(config));
+    config_load(&config);
+
+    const char *name = cli_theme_name;
+    if (name == NULL) {
+        name = getenv("DAF_THEME");
+    }
+    if (name == NULL && config.theme_name[0] != '\0') {
+        name = config.theme_name;
+    }
+    if (name == NULL) {
+        name = theme_build_default_name();
+    }
+
+    const theme_t *theme = theme_find(name);
+    if (theme == NULL) {
+        fprintf(stderr, "daf: unknown theme \"%s\", falling back to \"dark\"\n", name);
+        theme = theme_find("dark");
+    }
+    return theme;
+}
+
 int main(int argc, char **argv)
 {
-    if (argc > 2) {
-        fprintf(stderr, "usage: daf [file]\n");
-        return EXIT_FAILURE;
+    const char *cli_theme_name = NULL;
+    const char *filename = NULL;
+
+    for (int i = 1; i < argc; i++) {
+        if (strncmp(argv[i], "--theme=", 8) == 0) {
+            cli_theme_name = argv[i] + 8;
+        } else if (filename == NULL) {
+            filename = argv[i];
+        } else {
+            fprintf(stderr, "usage: daf [--theme=name] [file]\n");
+            return EXIT_FAILURE;
+        }
     }
 
+    const theme_t *theme = resolve_theme(cli_theme_name);
+
     terminal_enable_raw_mode();
 
     int rows;
@@ -35,9 +74,10 @@ int main(int argc, char **argv)
 
     editor_t ed;
     editor_init(&ed, text_rows_for(rows), cols);
+    ed.theme = theme;
 
-    if (argc == 2) {
-        editor_open(&ed, argv[1]);
+    if (filename != NULL) {
+        editor_open(&ed, filename);
     }
 
     while (!ed.should_quit) {

src/meson.build

@@ -3,6 +3,8 @@ daf_lib_sources = files(
   'terminal.c',
   'encoding.c',
   'filetype.c',
+  'theme.c',
+  'config.c',
   'buffer.c',
   'search.c',
   'render.c',