package tree

import (
	"sort"
	"strings"

	"dirmd/internal/walker"
)

type Node struct {
	Name     string
	IsDir    bool
	Children map[string]*Node
}

func Build(entries []walker.Entry) *Node {
	root := &Node{IsDir: true, Children: make(map[string]*Node)}

	for _, e := range entries {
		parts := strings.Split(e.RelPath, "/")
		cur := root

		for i, part := range parts {
			isLeaf := i == len(parts)-1
			if _, ok := cur.Children[part]; !ok {
				cur.Children[part] = &Node{Name: part, IsDir: !isLeaf, Children: make(map[string]*Node)}
			}
			cur = cur.Children[part]
		}
	}

	return root
}

func Render(root *Node, rootName string) string {
	var sb strings.Builder
	sb.WriteString(rootName)
	sb.WriteString("/\n")
	renderNode(&sb, root, "")
	return sb.String()
}

func renderNode(sb *strings.Builder, node *Node, prefix string) {
	keys := make([]string, 0, len(node.Children))
	for k := range node.Children {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	for i, key := range keys {
		child := node.Children[key]
		isLast := i == len(keys)-1

		if isLast {
			sb.WriteString(prefix + "└── ")
		} else {
			sb.WriteString(prefix + "├── ")
		}

		sb.WriteString(child.Name)
		if child.IsDir {
			sb.WriteString("/")
		}
		sb.WriteString("\n")

		if child.IsDir {
			newPrefix := prefix
			if isLast {
				newPrefix += "    "
			} else {
				newPrefix += "│   "
			}
			renderNode(sb, child, newPrefix)
		}
	}
}