1 files changed, 44 insertions, 0 deletions
diff --git a/app/headerlayout.go b/app/headerlayout.go
new file mode 100644
index 00000000..d9304dea
--- /dev/null
+++ b/app/headerlayout.go
@@ -0,0 +1,44 @@
+package app
+
+import (
+	"git.sr.ht/~rjarry/aerc/lib/ui"
+	"git.sr.ht/~rjarry/aerc/models"
+)
+
+type HeaderLayout [][]string
+
+type HeaderLayoutFilter struct {
+	layout HeaderLayout
+	keep   func(msg *models.MessageInfo, header string) bool // filter criteria
+}
+
+// forMessage returns a filtered header layout, removing rows whose headers
+// do not appear in the provided message.
+func (filter HeaderLayoutFilter) forMessage(msg *models.MessageInfo) HeaderLayout {
+	result := make(HeaderLayout, 0, len(filter.layout))
+	for _, row := range filter.layout {
+		// To preserve layout alignment, only hide rows if all columns are empty
+		for _, col := range row {
+			if filter.keep(msg, col) {
+				result = append(result, row)
+				break
+			}
+		}
+	}
+	return result
+}
+
+// grid builds a ui grid, populating each cell by calling a callback function
+// with the current header string.
+func (layout HeaderLayout) grid(cb func(string) ui.Drawable) (grid *ui.Grid, height int) {
+	rowCount := len(layout)
+	grid = ui.MakeGrid(rowCount, 1, ui.SIZE_EXACT, ui.SIZE_WEIGHT)
+	for i, cols := range layout {
+		r := ui.MakeGrid(1, len(cols), ui.SIZE_EXACT, ui.SIZE_WEIGHT)
+		for j, col := range cols {
+			r.AddChild(cb(col)).At(0, j)
+		}
+		grid.AddChild(r).At(i, 0)
+	}
+	return grid, rowCount
+}