templates: change fields as lazy functions

No need to pre-render fields that are not necessarily accessed in
templates. Change fields to functions that are evaluated only when
required.

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

10 files changed, 79 insertions, 50 deletions

diff --git a/commands/account/compose.go b/commands/account/compose.go
index fb37b231..5695bb7d 100644
--- a/commands/account/compose.go
+++ b/commands/account/compose.go
@@ -13,7 +13,6 @@ import (
 	"git.sr.ht/~rjarry/aerc/config"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
-	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/widgets"
 	"git.sr.ht/~sircmpwn/getopt"
 )
@@ -55,7 +54,7 @@ func (Compose) Execute(aerc *widgets.Aerc, args []string) error {
 
 	composer, err := widgets.NewComposer(aerc, acct,
 		acct.AccountConfig(), acct.Worker(),
-		template, &headers, models.OriginalMail{})
+		template, &headers, nil)
 	if err != nil {
 		return err
 	}
diff --git a/commands/account/recover.go b/commands/account/recover.go
index 8ce878ee..cef0720f 100644
--- a/commands/account/recover.go
+++ b/commands/account/recover.go
@@ -10,7 +10,6 @@ import (
 	"git.sr.ht/~rjarry/aerc/commands"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
-	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/widgets"
 	"git.sr.ht/~sircmpwn/getopt"
 )
@@ -103,7 +102,7 @@ func (Recover) Execute(aerc *widgets.Aerc, args []string) error {
 
 	composer, err := widgets.NewComposer(aerc, acct,
 		acct.AccountConfig(), acct.Worker(),
-		"", nil, models.OriginalMail{})
+		"", nil, nil)
 	if err != nil {
 		return err
 	}
diff --git a/commands/msg/forward.go b/commands/msg/forward.go
index 9a4f3d41..90c32ec2 100644
--- a/commands/msg/forward.go
+++ b/commands/msg/forward.go
@@ -101,7 +101,7 @@ func (forward) Execute(aerc *widgets.Aerc, args []string) error {
 
 	addTab := func() (*widgets.Composer, error) {
 		composer, err := widgets.NewComposer(aerc, acct,
-			acct.AccountConfig(), acct.Worker(), template, h, original)
+			acct.AccountConfig(), acct.Worker(), template, h, &original)
 		if err != nil {
 			aerc.PushError("Error: " + err.Error())
 			return nil, err
diff --git a/commands/msg/invite.go b/commands/msg/invite.go
index ef28b91c..1528abea 100644
--- a/commands/msg/invite.go
+++ b/commands/msg/invite.go
@@ -139,7 +139,7 @@ func (invite) Execute(aerc *widgets.Aerc, args []string) error {
 
 	addTab := func(cr *calendar.Reply) error {
 		composer, err := widgets.NewComposer(aerc, acct,
-			acct.AccountConfig(), acct.Worker(), "", h, original)
+			acct.AccountConfig(), acct.Worker(), "", h, &original)
 		if err != nil {
 			aerc.PushError("Error: " + err.Error())
 			return err
diff --git a/commands/msg/recall.go b/commands/msg/recall.go
index f106e8bd..2ef468e0 100644
--- a/commands/msg/recall.go
+++ b/commands/msg/recall.go
@@ -74,7 +74,7 @@ func (Recall) Execute(aerc *widgets.Aerc, args []string) error {
 
 	composer, err := widgets.NewComposer(aerc, acct,
 		acct.AccountConfig(), acct.Worker(), "", msgInfo.RFC822Headers,
-		models.OriginalMail{})
+		nil)
 	if err != nil {
 		return errors.Wrap(err, "Cannot open a new composer")
 	}
diff --git a/commands/msg/reply.go b/commands/msg/reply.go
index 795158ca..f8cde644 100644
--- a/commands/msg/reply.go
+++ b/commands/msg/reply.go
@@ -175,7 +175,8 @@ func (reply) Execute(aerc *widgets.Aerc, args []string) error {
 	mv, _ := aerc.SelectedTabContent().(*widgets.MessageViewer)
 	addTab := func() error {
 		composer, err := widgets.NewComposer(aerc, acct,
-			acct.AccountConfig(), acct.Worker(), template, h, original)
+			acct.AccountConfig(), acct.Worker(), template, h,
+			&original)
 		if err != nil {
 			aerc.PushError("Error: " + err.Error())
 			return err
diff --git a/commands/msg/unsubscribe.go b/commands/msg/unsubscribe.go
index a334e827..66797660 100644
--- a/commands/msg/unsubscribe.go
+++ b/commands/msg/unsubscribe.go
@@ -11,7 +11,6 @@ import (
 	"git.sr.ht/~rjarry/aerc/lib"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
-	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/widgets"
 	"github.com/emersion/go-message/mail"
 )
@@ -155,7 +154,7 @@ func unsubscribeMailto(aerc *widgets.Aerc, u *url.URL) error {
 		acct.Worker(),
 		"",
 		h,
-		models.OriginalMail{},
+		nil,
 	)
 	if err != nil {
 		return err
diff --git a/lib/templates/data.go b/lib/templates/data.go
index 5b351816..8637aa7f 100644
--- a/lib/templates/data.go
+++ b/lib/templates/data.go
@@ -8,51 +8,83 @@ import (
 )
 
 type TemplateData struct {
-	To      []*mail.Address
-	Cc      []*mail.Address
-	Bcc     []*mail.Address
-	From    []*mail.Address
-	Date    time.Time
-	Subject string
+	msg *mail.Header
 	// Only available when replying with a quote
-	OriginalText     string
-	OriginalFrom     []*mail.Address
-	OriginalDate     time.Time
-	OriginalMIMEType string
+	parent *models.OriginalMail
 }
 
-func ParseTemplateData(h *mail.Header, original models.OriginalMail) TemplateData {
-	// we ignore errors as this shouldn't fail the sending / replying even if
-	// something is wrong with the message we reply to
-	to, _ := h.AddressList("to")
-	cc, _ := h.AddressList("cc")
-	bcc, _ := h.AddressList("bcc")
-	from, _ := h.AddressList("from")
-	subject, err := h.Text("subject")
+func NewTemplateData(
+	msg *mail.Header, parent *models.OriginalMail,
+) *TemplateData {
+	return &TemplateData{
+		msg:    msg,
+		parent: parent,
+	}
+}
+
+func (d *TemplateData) To() []*mail.Address {
+	to, _ := d.msg.AddressList("to")
+	return to
+}
+
+func (d *TemplateData) Cc() []*mail.Address {
+	to, _ := d.msg.AddressList("cc")
+	return to
+}
+
+func (d *TemplateData) Bcc() []*mail.Address {
+	to, _ := d.msg.AddressList("bcc")
+	return to
+}
+
+func (d *TemplateData) From() []*mail.Address {
+	to, _ := d.msg.AddressList("from")
+	return to
+}
+
+func (d *TemplateData) Date() time.Time {
+	return time.Now()
+}
+
+func (d *TemplateData) Subject() string {
+	subject, err := d.msg.Text("subject")
 	if err != nil {
-		subject = h.Get("subject")
+		subject = d.msg.Get("subject")
+	}
+	return subject
+}
+
+func (d *TemplateData) OriginalText() string {
+	if d.parent == nil {
+		return ""
 	}
+	return d.parent.Text
+}
 
-	td := TemplateData{
-		To:               to,
-		Cc:               cc,
-		Bcc:              bcc,
-		From:             from,
-		Date:             time.Now(),
-		Subject:          subject,
-		OriginalText:     original.Text,
-		OriginalDate:     original.Date,
-		OriginalMIMEType: original.MIMEType,
+func (d *TemplateData) OriginalDate() time.Time {
+	if d.parent == nil {
+		return time.Time{}
 	}
-	if original.RFC822Headers != nil {
-		origFrom, _ := original.RFC822Headers.AddressList("from")
-		td.OriginalFrom = origFrom
+	return d.parent.Date
+}
+
+func (d *TemplateData) OriginalFrom() []*mail.Address {
+	if d.parent == nil || d.parent.RFC822Headers == nil {
+		return nil
+	}
+	from, _ := d.parent.RFC822Headers.AddressList("from")
+	return from
+}
+
+func (d *TemplateData) OriginalMIMEType() string {
+	if d.parent == nil {
+		return ""
 	}
-	return td
+	return d.parent.MIMEType
 }
 
 // DummyData provides dummy data to test template validity
-func DummyData() interface{} {
+func DummyData() *TemplateData {
 	from := &mail.Address{
 		Name:    "John Doe",
 		Address: "john@example.com",
@@ -76,5 +108,5 @@ func DummyData() interface{} {
 		MIMEType:      "text/plain",
 		RFC822Headers: oh,
 	}
-	return ParseTemplateData(h, original)
+	return NewTemplateData(h, &original)
 }
diff --git a/widgets/aerc.go b/widgets/aerc.go
index f6e5c1ff..eb904ea0 100644
--- a/widgets/aerc.go
+++ b/widgets/aerc.go
@@ -20,7 +20,6 @@ import (
 	"git.sr.ht/~rjarry/aerc/lib/crypto"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
-	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/worker/types"
 )
 
@@ -710,7 +709,7 @@ func (aerc *Aerc) Mailto(addr *url.URL) error {
 	}
 
 	composer, err := NewComposer(aerc, acct,
-		acct.AccountConfig(), acct.Worker(), "", h, models.OriginalMail{})
+		acct.AccountConfig(), acct.Worker(), "", h, nil)
 	if err != nil {
 		return nil
 	}
diff --git a/widgets/compose.go b/widgets/compose.go
index 782e7538..c59fa8ef 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -33,7 +33,7 @@ type Composer struct {
 	sync.Mutex
 	editors map[string]*headerEditor // indexes in lower case (from / cc / bcc)
 	header  *mail.Header
-	parent  models.OriginalMail // parent of current message, only set if reply
+	parent  *models.OriginalMail // parent of current message, only set if reply
 
 	acctConfig *config.AccountConfig
 	acct       *AccountView
@@ -68,7 +68,7 @@ type Composer struct {
 func NewComposer(
 	aerc *Aerc, acct *AccountView, acctConfig *config.AccountConfig,
 	worker *types.Worker, template string,
-	h *mail.Header, orig models.OriginalMail,
+	h *mail.Header, orig *models.OriginalMail,
 ) (*Composer, error) {
 	if h == nil {
 		h = new(mail.Header)
@@ -93,7 +93,7 @@ func NewComposer(
 		completer: nil,
 	}
 
-	templateData := templates.ParseTemplateData(h, orig)
+	templateData := templates.NewTemplateData(h, orig)
 	if err := c.AddTemplate(template, templateData); err != nil {
 		return nil, err
 	}