Add pkg/util/dirtree

Update dir_tree tool to use it
Update filepicker bubble to use it

pkg/util/dirtree/render.go

@@ -0,0 +1,82 @@
+package dirtree
+
+import "strings"
+
+// FlattenTree returns []*Node consistent with each node's `Expanded` state
+func FlattenTree(node *Node, expandAll bool) []*Node {
+	lines := make([]*Node, 0)
+	var flatten func(n *Node)
+	flatten = func(node *Node) {
+		lines = append(lines, node)
+		if node.isDir && (node.Expanded || expandAll) {
+			for _, child := range node.children {
+				flatten(child)
+			}
+		}
+	}
+	flatten(node)
+	return lines
+}
+
+type TreeFormat struct {
+	Space    string
+	Span     string
+	Node     string
+	NodeLast string
+}
+
+var (
+	Standard = TreeFormat{
+		Space:    "    ",
+		Span:     "│   ",
+		Node:     "├── ",
+		NodeLast: "└── ",
+	}
+	Compact = TreeFormat{
+		Space:    "  ",
+		Span:     "│ ",
+		Node:     "├ ",
+		NodeLast: "└ ",
+	}
+)
+
+func RenderNodes(displayNodes []*Node, format TreeFormat, cursor int, renderNode func(*Node) string) string {
+	var sb strings.Builder
+	levelIsLast := make(map[int]bool)
+	for i, node := range displayNodes {
+		// Cursor indicator
+		if cursor >= 0 {
+			if i == cursor {
+				sb.WriteString("> ")
+			} else {
+				sb.WriteString("  ")
+			}
+		}
+
+		// Tree structure
+		if node.depth > 0 {
+			for d := 1; d < node.depth; d++ {
+				if levelIsLast[d] {
+					sb.WriteString(format.Space)
+				} else {
+					sb.WriteString(format.Span)
+				}
+			}
+
+			// Find if this node is the last among its siblings
+			isLast := node.parent.children[len(node.parent.children)-1] == node
+			levelIsLast[node.depth] = isLast
+
+			if isLast {
+				sb.WriteString(format.NodeLast)
+			} else {
+				sb.WriteString(format.Node)
+			}
+		}
+
+		// Render the node
+		sb.WriteString(renderNode(node))
+		sb.WriteString("\n")
+	}
+	return sb.String()
+}