templates: unify data interface

Require that all aerc template data objects implement the same
TemplateData interface.

Implement that interface in two different places:

1) state.TemplateData (renamed/moved from templates.TemplateData).
   This structure (along with all its methods) needs to be decoupled
   from the templates package to break the import cycle with the config
   package. This allows much simpler construction of this object and
   ensure that values are calculated only when requested.

2) config.dummyData (extracted from templates).
   This is only used in the config package to validate user templates.
   Putting it here allows also to break an import cycle.

Use state.TemplateData everywhere (including for account tabs title
rendering).

Signed-off-by: Robin Jarry <robin@jarry.cc>
Reviewed-by: Moritz Poldrack <moritz@poldrack.dev>

3 files changed, 37 insertions, 74 deletions

diff --git a/widgets/account.go b/widgets/account.go
index 85043d1f..3176a2bf 100644
--- a/widgets/account.go
+++ b/widgets/account.go
@@ -13,7 +13,9 @@ import (
 	"git.sr.ht/~rjarry/aerc/lib"
 	"git.sr.ht/~rjarry/aerc/lib/marker"
 	"git.sr.ht/~rjarry/aerc/lib/sort"
+	"git.sr.ht/~rjarry/aerc/lib/state"
 	"git.sr.ht/~rjarry/aerc/lib/statusline"
+	"git.sr.ht/~rjarry/aerc/lib/templates"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
 	"git.sr.ht/~rjarry/aerc/models"
@@ -597,23 +599,14 @@ func (acct *AccountView) Vsplit(n int) error {
 
 // setTitle executes the title template and sets the tab title
 func (acct *AccountView) setTitle() {
-	data := struct {
-		Account string
-		Recent  int
-		Unread  int
-		Exists  int
-		Folder  string
-	}{}
-	data.Account = acct.Name()
-	data.Folder = acct.SelectedDirectory()
-	for _, name := range acct.dirlist.List() {
-		r, u, e := acct.dirlist.GetRUECount(name)
-		data.Recent += r
-		data.Unread += u
-		data.Exists += e
-	}
-	buf := bytes.NewBuffer(nil)
-	err := acct.uiConf.TabTitleAccount.Execute(buf, data)
+	var data state.TemplateData
+
+	data.SetAccount(acct.acct)
+	data.SetFolder(acct.SelectedDirectory())
+	data.SetRUE(acct.dirlist.List(), acct.dirlist.GetRUECount)
+
+	var buf bytes.Buffer
+	err := templates.Render(acct.uiConf.TabTitleAccount, &buf, &data)
 	if err != nil {
 		acct.PushError(err)
 		return
diff --git a/widgets/compose.go b/widgets/compose.go
index 7311de7a..b74e1537 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -23,6 +23,7 @@ import (
 	"git.sr.ht/~rjarry/aerc/config"
 	"git.sr.ht/~rjarry/aerc/lib"
 	"git.sr.ht/~rjarry/aerc/lib/format"
+	"git.sr.ht/~rjarry/aerc/lib/state"
 	"git.sr.ht/~rjarry/aerc/lib/templates"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
@@ -95,21 +96,11 @@ func NewComposer(
 		completer: nil,
 	}
 
-	uiConfig := acct.UiConfig()
-
-	templateData := templates.NewTemplateData(
-		acct.acct.From,
-		acct.acct.Aliases,
-		acct.Name(),
-		acct.Directories().Selected(),
-		uiConfig.MessageViewTimestampFormat,
-		uiConfig.MessageViewThisDayTimeFormat,
-		uiConfig.MessageViewThisWeekTimeFormat,
-		uiConfig.MessageViewThisYearTimeFormat,
-		uiConfig.IconAttachment,
-	)
-	templateData.SetHeaders(h, orig)
-	if err := c.AddTemplate(template, templateData); err != nil {
+	var data state.TemplateData
+	data.SetAccount(acct.acct)
+	data.SetFolder(acct.Directories().Selected())
+	data.SetHeaders(h, orig)
+	if err := c.AddTemplate(template, &data); err != nil {
 		return nil, err
 	}
 	c.AddSignature()
@@ -509,7 +500,7 @@ func (c *Composer) RemovePart(mimetype string) error {
 	return fmt.Errorf("%s part not found", mimetype)
 }
 
-func (c *Composer) AddTemplate(template string, data interface{}) error {
+func (c *Composer) AddTemplate(template string, data models.TemplateData) error {
 	if template == "" {
 		return nil
 	}
@@ -1551,37 +1542,24 @@ func (c *Composer) setTitle() {
 	if c.Tab == nil {
 		return
 	}
-	data := struct {
-		Account      string
-		Subject      string
-		To           []*mail.Address
-		From         []*mail.Address
-		Cc           []*mail.Address
-		Bcc          []*mail.Address
-		OriginalFrom []*mail.Address
-	}{}
-	data.Account = c.acct.Name()
+
+	var data state.TemplateData
+
+	header := c.header.Copy()
 	// Get subject direct from the textinput
 	subject, ok := c.editors["subject"]
 	if ok {
-		data.Subject = subject.input.String()
-	}
-	if data.Subject == "" {
-		data.Subject = "New Email"
+		header.SetSubject(subject.input.String())
 	}
-	// Get address fields from header, which gets updated on focus lost of
-	// any headerEditor field
-	data.From, _ = c.header.AddressList("from")
-	data.To, _ = c.header.AddressList("to")
-	data.Cc, _ = c.header.AddressList("cc")
-	data.Bcc, _ = c.header.AddressList("bcc")
-
-	if c.parent != nil && c.parent.RFC822Headers != nil {
-		data.OriginalFrom, _ = c.parent.RFC822Headers.AddressList("from")
+	if header.Get("subject") == "" {
+		header.SetSubject("New Email")
 	}
+	data.SetAccount(c.acctConfig)
+	data.SetFolder(c.acct.SelectedDirectory())
+	data.SetHeaders(&header, c.parent)
 
-	buf := bytes.NewBuffer(nil)
-	err := c.acct.UiConfig().TabTitleComposer.Execute(buf, data)
+	var buf bytes.Buffer
+	err := templates.Render(c.acct.UiConfig().TabTitleComposer, &buf, &data)
 	if err != nil {
 		c.acct.PushError(err)
 		return
diff --git a/widgets/msglist.go b/widgets/msglist.go
index 85072d1e..4b2bf721 100644
--- a/widgets/msglist.go
+++ b/widgets/msglist.go
@@ -11,7 +11,7 @@ import (
 	"git.sr.ht/~rjarry/aerc/config"
 	"git.sr.ht/~rjarry/aerc/lib"
 	"git.sr.ht/~rjarry/aerc/lib/iterator"
-	"git.sr.ht/~rjarry/aerc/lib/templates"
+	"git.sr.ht/~rjarry/aerc/lib/state"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
 	"git.sr.ht/~rjarry/aerc/models"
@@ -87,19 +87,11 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 		return
 	}
 
-	data := templates.NewTemplateData(
-		acct.acct.From,
-		acct.acct.Aliases,
-		acct.Name(),
-		acct.Directories().Selected(),
-		uiConfig.TimestampFormat,
-		uiConfig.ThisDayTimeFormat,
-		uiConfig.ThisWeekTimeFormat,
-		uiConfig.ThisYearTimeFormat,
-		uiConfig.IconAttachment,
-	)
-
 	var needsHeaders []uint32
+	var data state.TemplateData
+
+	data.SetAccount(acct.acct)
+	data.SetFolder(acct.Directories().Selected())
 
 	customDraw := func(t *ui.Table, r int, c *ui.Context) bool {
 		row := &t.Rows[r]
@@ -175,7 +167,7 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 				lastSubject = baseSubject
 				prevThread = thread
 
-				if addMessage(store, thread.Uid, &table, data, uiConfig) {
+				if addMessage(store, thread.Uid, &table, &data, uiConfig) {
 					break threadLoop
 				}
 			}
@@ -187,7 +179,7 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 				continue
 			}
 			uid := iter.Value().(uint32)
-			if addMessage(store, uid, &table, data, uiConfig) {
+			if addMessage(store, uid, &table, &data, uiConfig) {
 				break
 			}
 		}
@@ -220,7 +212,7 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 
 func addMessage(
 	store *lib.MessageStore, uid uint32,
-	table *ui.Table, data *templates.TemplateData,
+	table *ui.Table, data *state.TemplateData,
 	uiConfig *config.UIConfig,
 ) bool {
 	msg := store.Messages[uid]