[bug#57963] [PATCH v3] home: fontutils: Support user's fontconfig.

[Taiju HIGASHI <higashi@taiju.info>]

* gnu/home/services/fontutils.scm (add-fontconfig-config-file): Support user's
fontconfig.
---
 gnu/home/services/fontutils.scm | 103 ++++++++++++++++++++++++++++++--
 1 file changed, 97 insertions(+), 6 deletions(-)

diff --git a/gnu/home/services/fontutils.scm b/gnu/home/services/fontutils.scm
index 6062eaed6a..b02f43a4fc 100644
--- a/gnu/home/services/fontutils.scm
+++ b/gnu/home/services/fontutils.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2021 Andrew Tropin <andrew@trop.in>
 ;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
+;;; Copyright © 2022 Taiju HIGASHI <higashi@taiju.info>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -20,9 +21,16 @@
 (define-module (gnu home services fontutils)
   #:use-module (gnu home services)
   #:use-module (gnu packages fontutils)
+  #:use-module (gnu services configuration)
   #:use-module (guix gexp)
+  #:use-module (guix records)
+  #:use-module (srfi srfi-1)
+  #:use-module (sxml simple)
+  #:use-module (ice-9 match)
 
-  #:export (home-fontconfig-service-type))
+  #:export (home-fontconfig-service-type
+            home-fontconfig-configuration
+            default-font))
 
 ;;; Commentary:
 ;;;
@@ -33,15 +41,96 @@ (define-module (gnu home services fontutils)
 ;;;
 ;;; Code:
 
-(define (add-fontconfig-config-file he-symlink-path)
+(define-record-type* <default-font> default-font
+  make-default-font
+  default-font?
+  (serif default-font-serif (default ""))
+  (sans-serif defalut-font-sans-serif (default ""))
+  (monospace default-font-monospace (default "")))
+
+(define (sxml->xmlstring sxml)
+  (if (null? sxml)
+      ""
+      (call-with-output-string
+        (lambda (port)
+          (sxml->xml sxml port)
+          (newline port)))))
+
+(define font-directories? list?)
+
+(define (serialize-font-directories field-name value)
+  (sxml->xmlstring
+   (append
+       '((dir "~/.guix-home/profile/share/fonts"))
+       (map
+        (lambda (path)
+          `(dir ,path))
+        value))))
+
+(define extra-config-list? list?)
+
+(define (serialize-extra-config-list field-name value)
+  (sxml->xmlstring
+   (map (match-lambda
+          ((? pair? sxml) sxml)
+          ((? string? xml) (xml->sxml xml))
+          (_ (error "extra-config value must be xml string or sxml list.")))
+        value)))
+
+(define (serialize-default-font field-name value)
+  (match value
+    (($ <default-font> serif sans-serif monospace)
+     (sxml->xmlstring
+      (fold (lambda (pair sxml)
+              (if (string-null? (cdr pair))
+                  sxml
+                  (append sxml
+                      `((alias
+                         (family ,(car pair))
+                         (prefer
+                          (family ,(cdr pair))))))))
+            '()
+            `((serif . ,serif)
+              (sans-serif . ,sans-serif)
+              (monospace . ,monospace)))))))
+
+(define-configuration home-fontconfig-configuration
+  (font-directories
+   (font-directories '())
+   "The directory list that provides fonts.")
+  (preferred-default-font
+   (default-font (default-font))
+   "The preffered default fonts for serif, sans-serif, and monospace.")
+  (extra-config
+   (extra-config-list '())
+   "Extra configuration values to append to the fonts.conf."))
+
+(define (home-fontconfig-extend original-config extend-configs)
+  (home-fontconfig-configuration
+   (inherit original-config)
+   (font-directories
+    (append
+        (home-fontconfig-configuration-font-directories original-config)
+        (append-map home-fontconfig-configuration-font-directories extend-configs)))
+   (preferred-default-font
+    (home-fontconfig-configuration-preferred-default-font
+     (if (null? extend-configs)
+         original-config
+         (last extend-configs))))
+   (extra-config
+    (append
+        (home-fontconfig-configuration-extra-config original-config)
+        (append-map home-fontconfig-configuration-extra-config extend-configs)))))
+
+(define (add-fontconfig-config-file user-config)
   `(("fontconfig/fonts.conf"
      ,(mixed-text-file
        "fonts.conf"
        "<?xml version='1.0'?>
 <!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
-<fontconfig>
-  <dir>~/.guix-home/profile/share/fonts</dir>
-</fontconfig>"))))
+<fontconfig>\n"
+       (serialize-configuration user-config home-fontconfig-configuration-fields)
+       "</fontconfig>\n"))))
 
 (define (regenerate-font-cache-gexp _)
   `(("profile/share/fonts"
@@ -49,6 +138,8 @@ (define (regenerate-font-cache-gexp _)
 
 (define home-fontconfig-service-type
   (service-type (name 'home-fontconfig)
+                (compose identity)
+                (extend home-fontconfig-extend)
                 (extensions
                  (list (service-extension
                         home-xdg-configuration-files-service-type
@@ -59,7 +150,7 @@ (define home-fontconfig-service-type
                        (service-extension
                         home-profile-service-type
                         (const (list fontconfig)))))
-                (default-value #f)
+                (default-value (home-fontconfig-configuration))
                 (description
                  "Provides configuration file for fontconfig and make
 fc-* utilities aware of font packages installed in Guix Home's profile.")))
-- 
2.37.3