config: use reflection to map ini keys to struct fields

The default ini.Section.MapTo() function only handles basic types.
Implement a more complete mapping solution that allows:

* parsing templates, regexps, email addresses
* defining a custom parsing method via the `parse:"MethodName"` tag
* defining default values via the `default:"value"` tag
* parsing rune values with the `type:"rune"` tag

The field name must be specified in the `ini:"field-name"` tag as it was
before. It is no longer optional.

The `delim:"<separator>"` tag remains but can only be used to parse
string arrays.

It is now possible to override default values with "zero" values. For
example:

	[ui]
	dirlist-delay = 0

Will override the default "200ms" value. Also:

	[statusline]
	status-columns =

Will override the default "left<*,center>=,right>*" value.

Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Tim Culverhouse <tim@timculverhouse.com>

1 files changed, 14 insertions, 40 deletions

diff --git a/config/compose.go b/config/compose.go
index 14a3087b..70533453 100644
--- a/config/compose.go
+++ b/config/compose.go
@@ -1,7 +1,6 @@
 package config
 
 import (
-	"fmt"
 	"regexp"
 
 	"git.sr.ht/~rjarry/aerc/log"
@@ -10,54 +9,29 @@ import (
 
 type ComposeConfig struct {
 	Editor              string         `ini:"editor"`
-	HeaderLayout        [][]string     `ini:"-"`
+	HeaderLayout        [][]string     `ini:"header-layout" parse:"ParseLayout" default:"To|From,Subject"`
 	AddressBookCmd      string         `ini:"address-book-cmd"`
-	ReplyToSelf         bool           `ini:"reply-to-self"`
-	NoAttachmentWarning *regexp.Regexp `ini:"-"`
+	ReplyToSelf         bool           `ini:"reply-to-self" default:"true"`
+	NoAttachmentWarning *regexp.Regexp `ini:"no-attachment-warning" parse:"ParseNoAttachmentWarning"`
 	FilePickerCmd       string         `ini:"file-picker-cmd"`
 	FormatFlowed        bool           `ini:"format-flowed"`
 }
 
-func defaultComposeConfig() *ComposeConfig {
-	return &ComposeConfig{
-		HeaderLayout: [][]string{
-			{"To", "From"},
-			{"Subject"},
-		},
-		ReplyToSelf: true,
-	}
-}
-
-var Compose = defaultComposeConfig()
+var Compose = new(ComposeConfig)
 
 func parseCompose(file *ini.File) error {
-	compose, err := file.GetSection("compose")
-	if err != nil {
-		goto end
-	}
-
-	if err := compose.MapTo(&Compose); err != nil {
+	if err := MapToStruct(file.Section("compose"), Compose, true); err != nil {
 		return err
 	}
-	for key, val := range compose.KeysHash() {
-		if key == "header-layout" {
-			Compose.HeaderLayout = parseLayout(val)
-		}
-
-		if key == "no-attachment-warning" && len(val) > 0 {
-			re, err := regexp.Compile("(?im)" + val)
-			if err != nil {
-				return fmt.Errorf(
-					"Invalid no-attachment-warning '%s': %w",
-					val, err,
-				)
-			}
-
-			Compose.NoAttachmentWarning = re
-		}
-	}
-
-end:
 	log.Debugf("aerc.conf: [compose] %#v", Compose)
 	return nil
 }
+
+func (c *ComposeConfig) ParseLayout(sec *ini.Section, key *ini.Key) ([][]string, error) {
+	layout := parseLayout(key.String())
+	return layout, nil
+}
+
+func (c *ComposeConfig) ParseNoAttachmentWarning(sec *ini.Section, key *ini.Key) (*regexp.Regexp, error) {
+	return regexp.Compile(`(?im)` + key.String())
+}