Add basic filter implementation

2 files changed, 67 insertions, 25 deletions

diff --git a/config/aerc.conf b/config/aerc.conf
index 5a4317f4..3a891514 100644
--- a/config/aerc.conf
+++ b/config/aerc.conf
@@ -54,32 +54,12 @@ empty-message=(no messages)
 
 [viewer]
 #
-# We can use different programs to display various kinds of email attachments.
-# These programs will have the mail piped into them and are expected to output
-# it ready to display on a terminal (you can include terminal control
-# characters if you like, for colors and such). Emails will be stripped of
-# non-printable characters before being piped into these commands, and will be
-# encoded with UTF-8. These commands are invoked with sh and run
-# non-interactively, and their output is piped into your pager command
-# (interactively). The following environment variables will be set:
+# Specifies the pager to use when displaying emails. Note that some filters
+# may add ANSI codes to add color to rendered emails, so you may want to use a
+# pager which supports ANSI codes.
 #
-# $WIDTH: the width of the terminal window
-# $HEIGHT: the height of the terminal window
-# $MIMETYPE: the email's mimetype
-#
-# You can use * as a wildcard for any subtype of a given mimetype. When
-# displaying a text/* message and no command matches, the message will just be
-# piped directly into your pager (after being stripped of non-printable
-# characters).
-
-# Examples:
-#
-#text/html=w3m -T text/html -cols $WIDTH -dump -o display_image=false -o display_link_number=true
-text/*=fold -sw $WIDTH
-
-#
-# Default: less -r
-pager=less -r
+# Default: less -R
+pager=less -R
 
 #
 # If an email offers several versions (multipart), you can configure which
@@ -89,6 +69,21 @@ pager=less -r
 # Default: text/plain,text/html
 alternatives=text/plain,text/html
 
+[filters]
+#
+# Filters allow you to pipe an email body through a shell command to render
+# certain emails differently, e.g. highlighting them with ANSI escape codes.
+#
+# The first filter which matches the email's mimetype will be used, so order
+# them from most to least specific.
+#
+# You can also match on non-mimetypes, by prefixing with the header to match
+# against (non-case-sensitive) and a colon, e.g. subject:text will match a
+# subject which contains "text". Use header~:regex to match against a regex.
+subject~:PATCH=contrib/hldiff.py
+text/html=w3m -T text/html -cols $(tput cols) -dump -o display_image=false -o display_link_number=true
+text/*=contrib/plaintext.py
+
 [lbinds]
 #
 # Binds are of the form <input keys> = <output keys>
diff --git a/config/config.go b/config/config.go
index e5e332e7..8d460ca6 100644
--- a/config/config.go
+++ b/config/config.go
@@ -22,6 +22,12 @@ type UIConfig struct {
 	EmptyMessage      string   `ini:"empty-message"`
 }
 
+const (
+	FILTER_MIMETYPE = iota
+	FILTER_HEADER
+	FILTER_HEADER_REGEX
+)
+
 type AccountConfig struct {
 	Default string
 	Name    string
@@ -38,10 +44,23 @@ type BindingConfig struct {
 	Terminal    *KeyBindings
 }
 
+type FilterConfig struct {
+	FilterType int
+	Filter     string
+	Command    string
+}
+
+type ViewerConfig struct {
+	Pager        string
+	Alternatives []string
+}
+
 type AercConfig struct {
 	Bindings BindingConfig
 	Ini      *ini.File       `ini:"-"`
 	Accounts []AccountConfig `ini:"-"`
+	Filters  []FilterConfig  `ini:"-"`
+	Viewer   ViewerConfig    `ini:"-"`
 	Ui       UIConfig
 }
 
@@ -135,6 +154,34 @@ func LoadConfig(root *string) (*AercConfig, error) {
 			EmptyMessage:      "(no messages)",
 		},
 	}
+	if filters, err := file.GetSection("filters"); err == nil {
+		// TODO: Parse the filter more finely, e.g. parse the regex
+		for match, cmd := range filters.KeysHash() {
+			filter := FilterConfig{
+				Command: cmd,
+				Filter:  match,
+			}
+			if strings.Contains(match, "~:") {
+				filter.FilterType = FILTER_HEADER_REGEX
+			} else if strings.ContainsRune(match, ':') {
+				filter.FilterType = FILTER_HEADER
+			} else {
+				filter.FilterType = FILTER_MIMETYPE
+			}
+			config.Filters = append(config.Filters, filter)
+		}
+	}
+	if viewer, err := file.GetSection("viewer"); err == nil {
+		if err := viewer.MapTo(&config.Viewer); err != nil {
+			return nil, err
+		}
+		for key, val := range viewer.KeysHash() {
+			switch key {
+			case "alternatives":
+				config.Viewer.Alternatives = strings.Split(val, ",")
+			}
+		}
+	}
 	if ui, err := file.GetSection("ui"); err == nil {
 		if err := ui.MapTo(&config.Ui); err != nil {
 			return nil, err