git-get/pkg/print/tree.go

package print

import (
	"git-get/pkg/repo"
	"path/filepath"
	"strings"

	"github.com/xlab/treeprint"
)

type SimpleTreePrinter struct{}

type SmartTreePrinter struct {
	// length is the size (number of chars) of the currently processed line.
	// It's used to correctly indent the lines with branches status.
	length int
}

func (p *SmartTreePrinter) Print(root string, repos []*repo.Repo) string {
	tree := BuildTree(root, repos)

	return p.PrintSmartTree(tree)
}

func (p *SimpleTreePrinter) Print(root string, repos []*repo.Repo) string {
	tree := BuildTree(root, repos)

	tp := treeprint.New()
	tp.SetValue(root)

	p.PrintSimpleTree(tree, tp)

	return tp.String()
}

// Node represents a node (ie. path fragment) in a repos tree.
type Node struct {
	val      string
	depth    int // depth is a nesting depth used when rendering a smart tree, not a depth level of a tree node.
	parent   *Node
	children []*Node
	repo     *repo.Repo
}

// Root creates a new root of a tree
func Root(val string) *Node {
	root := &Node{
		val: val,
	}
	return root
}

// Add adds a child node
func (n *Node) Add(val string) *Node {
	if n.children == nil {
		n.children = make([]*Node, 0)
	}

	child := &Node{
		val:    val,
		parent: n,
	}
	n.children = append(n.children, child)
	return child
}

// GetChild finds a node with val inside this node's children (only 1 level deep).
// Returns pointer to found child or nil if node doesn't have any children or doesn't have a child with sought value.
func (n *Node) GetChild(val string) *Node {
	if n.children == nil {
		return nil
	}

	for _, child := range n.children {
		if child.val == val {
			return child
		}
	}

	return nil
}

// BuildTree builds a directory tree of paths to repositories.
// Each node represents a directory in the repo path.
// Each leaf (final node) contains a pointer to the repo.
func BuildTree(root string, repos []*repo.Repo) *Node {
	tree := Root(root)

	for _, r := range repos {
		path := strings.TrimPrefix(r.Path, root)
		path = strings.Trim(path, string(filepath.Separator))
		subs := strings.Split(path, string(filepath.Separator))

		// For each path fragment, start at the root of the tree
		// and check if the fragment exist among the children of the node.
		// If not, add it to node's children and move to next fragment.
		// If it does, just move to the next fragment.
		node := tree
		for i, sub := range subs {
			child := node.GetChild(sub)
			if child == nil {
				node = node.Add(sub)

				// If that's the last fragment, it's a tree leaf and needs a *Repo attached.
				if i == len(subs)-1 {
					node.repo = r
				}

				continue
			}
			node = child
		}
	}
	return tree
}

// PrintSmartTree returns a string representation of repos tree.
// It's "smart" because it automatically folds branches which only have a single child and indents branches with many children.
//
// It recursively traverses the tree and prints its nodes.
// If a node contains multiple children, they are be printed in new lines and indented.
// If a node contains only a single child, it is printed in the same line using path separator.
// For better readability the first level (repos hosts) is not indented.
//
// Example:
// Following paths:
//   /repos/github.com/user/repo1
//   /repos/github.com/user/repo2
//   /repos/github.com/another/repo
//
// will render a tree:
//   /repos/
//   github.com/
//       user/
//           repo1
//           repo2
//       another/repo
//
func (p *SmartTreePrinter) PrintSmartTree(node *Node) string {
	if node.children == nil {
		// If node is a leaf, print repo name and its status and finish processing this node.
		value := node.val

		// TODO: Ugly
		// If this is called from tests the repo will be nil and we should return just the name without the status.
		if node.repo.Repository == nil {
			return value
		}

		value += " " + printWorktreeStatus(node.repo)

		// Print the status of each branch on a new line, indented to match the position of the current branch name.
		indent := "\n" + strings.Repeat(" ", p.length+len(node.val))
		for _, branch := range node.repo.Status.Branches {
			// Don't print the status of the current branch. It was already printed above.
			if branch.Name == node.repo.Status.CurrentBranch {
				continue
			}

			value += indent + printBranchStatus(branch)
		}

		return value
	}

	val := node.val + string(filepath.Separator)

	shift := ""
	if node.parent == nil {
		// If node is a root, print its children on a new line without indentation.
		shift = "\n"
	} else if len(node.children) == 1 {
		// If node has only a single child, print it on the same line as its parent.
		// Setting node's depth to the same as parent's ensures that its children will be indented only once even if
		// node's path has multiple levels above.
		node.depth = node.parent.depth

		p.length += len(val)
	} else {
		// If node has multiple children, print each of them on a new line
		// and indent them once relative to the parent
		node.depth = node.parent.depth + 1
		shift = "\n" + strings.Repeat("    ", node.depth)
		p.length = 0
	}

	for _, child := range node.children {
		p.length += len(shift)
		val += shift + p.PrintSmartTree(child)
		p.length = 0
	}

	return val
}

func (p *SimpleTreePrinter) PrintSimpleTree(node *Node, tp treeprint.Tree) {
	if node.children == nil {
		tp.SetValue(node.val + " " + printWorktreeStatus(node.repo))

		for _, branch := range node.repo.Status.Branches {
			// Don't print the status of the current branch. It was already printed above.
			if branch.Name == node.repo.Status.CurrentBranch {
				continue
			}
			tp.AddNode(printBranchStatus(branch))
		}

	}

	for _, child := range node.children {
		branch := tp.AddBranch(child.val)
		p.PrintSimpleTree(child, branch)
	}
}