package taskwarrior

import (
	"testing"
)

func TestBuildTaskTree_EmptyList(t *testing.T) {
	tasks := Tasks{}
	tree := BuildTaskTree(tasks)

	if tree == nil {
		t.Fatal("Expected tree to be non-nil")
	}

	if len(tree.Nodes) != 0 {
		t.Errorf("Expected 0 nodes, got %d", len(tree.Nodes))
	}

	if len(tree.Roots) != 0 {
		t.Errorf("Expected 0 roots, got %d", len(tree.Roots))
	}

	if len(tree.FlatList) != 0 {
		t.Errorf("Expected 0 items in flat list, got %d", len(tree.FlatList))
	}
}

func TestBuildTaskTree_NoParents(t *testing.T) {
	tasks := Tasks{
		{Uuid: "task1", Description: "Task 1", Status: "pending"},
		{Uuid: "task2", Description: "Task 2", Status: "pending"},
		{Uuid: "task3", Description: "Task 3", Status: "completed"},
	}

	tree := BuildTaskTree(tasks)

	if len(tree.Nodes) != 3 {
		t.Errorf("Expected 3 nodes, got %d", len(tree.Nodes))
	}

	if len(tree.Roots) != 3 {
		t.Errorf("Expected 3 roots (all tasks have no parent), got %d", len(tree.Roots))
	}

	if len(tree.FlatList) != 3 {
		t.Errorf("Expected 3 items in flat list, got %d", len(tree.FlatList))
	}

	// All tasks should have depth 0
	for i, node := range tree.FlatList {
		if node.Depth != 0 {
			t.Errorf("Task %d expected depth 0, got %d", i, node.Depth)
		}
		if node.HasChildren() {
			t.Errorf("Task %d should not have children", i)
		}
	}
}

func TestBuildTaskTree_SimpleParentChild(t *testing.T) {
	tasks := Tasks{
		{Uuid: "parent1", Description: "Parent Task", Status: "pending"},
		{
			Uuid:        "child1",
			Description: "Child Task 1",
			Status:      "pending",
			Udas:        map[string]any{"parenttask": "parent1"},
		},
		{
			Uuid:        "child2",
			Description: "Child Task 2",
			Status:      "completed",
			Udas:        map[string]any{"parenttask": "parent1"},
		},
	}

	tree := BuildTaskTree(tasks)

	if len(tree.Nodes) != 3 {
		t.Fatalf("Expected 3 nodes, got %d", len(tree.Nodes))
	}

	if len(tree.Roots) != 1 {
		t.Fatalf("Expected 1 root, got %d", len(tree.Roots))
	}

	// Check root is the parent
	root := tree.Roots[0]
	if root.Task.Uuid != "parent1" {
		t.Errorf("Expected root to be parent1, got %s", root.Task.Uuid)
	}

	// Check parent has 2 children
	if len(root.Children) != 2 {
		t.Fatalf("Expected parent to have 2 children, got %d", len(root.Children))
	}

	// Check children status
	completed, total := root.GetChildrenStatus()
	if total != 2 {
		t.Errorf("Expected total children = 2, got %d", total)
	}
	if completed != 1 {
		t.Errorf("Expected completed children = 1, got %d", completed)
	}

	// Check flat list order (parent first, then children)
	if len(tree.FlatList) != 3 {
		t.Fatalf("Expected 3 items in flat list, got %d", len(tree.FlatList))
	}

	if tree.FlatList[0].Task.Uuid != "parent1" {
		t.Errorf("Expected first item to be parent, got %s", tree.FlatList[0].Task.Uuid)
	}

	if tree.FlatList[0].Depth != 0 {
		t.Errorf("Expected parent depth = 0, got %d", tree.FlatList[0].Depth)
	}

	// Children should be at depth 1
	for i := 1; i < 3; i++ {
		if tree.FlatList[i].Depth != 1 {
			t.Errorf("Expected child %d depth = 1, got %d", i, tree.FlatList[i].Depth)
		}
		if tree.FlatList[i].Parent == nil {
			t.Errorf("Child %d should have a parent", i)
		} else if tree.FlatList[i].Parent.Task.Uuid != "parent1" {
			t.Errorf("Child %d parent should be parent1, got %s", i, tree.FlatList[i].Parent.Task.Uuid)
		}
	}
}

func TestBuildTaskTree_MultiLevel(t *testing.T) {
	tasks := Tasks{
		{Uuid: "grandparent", Description: "Grandparent", Status: "pending"},
		{
			Uuid:        "parent1",
			Description: "Parent 1",
			Status:      "pending",
			Udas:        map[string]any{"parenttask": "grandparent"},
		},
		{
			Uuid:        "parent2",
			Description: "Parent 2",
			Status:      "pending",
			Udas:        map[string]any{"parenttask": "grandparent"},
		},
		{
			Uuid:        "child1",
			Description: "Child 1",
			Status:      "pending",
			Udas:        map[string]any{"parenttask": "parent1"},
		},
		{
			Uuid:        "grandchild1",
			Description: "Grandchild 1",
			Status:      "completed",
			Udas:        map[string]any{"parenttask": "child1"},
		},
	}

	tree := BuildTaskTree(tasks)

	if len(tree.Nodes) != 5 {
		t.Fatalf("Expected 5 nodes, got %d", len(tree.Nodes))
	}

	if len(tree.Roots) != 1 {
		t.Fatalf("Expected 1 root, got %d", len(tree.Roots))
	}

	// Find nodes by UUID
	grandparentNode := tree.Nodes["grandparent"]
	parent1Node := tree.Nodes["parent1"]
	child1Node := tree.Nodes["child1"]
	grandchildNode := tree.Nodes["grandchild1"]

	// Check depths
	if grandparentNode.Depth != 0 {
		t.Errorf("Expected grandparent depth = 0, got %d", grandparentNode.Depth)
	}
	if parent1Node.Depth != 1 {
		t.Errorf("Expected parent1 depth = 1, got %d", parent1Node.Depth)
	}
	if child1Node.Depth != 2 {
		t.Errorf("Expected child1 depth = 2, got %d", child1Node.Depth)
	}
	if grandchildNode.Depth != 3 {
		t.Errorf("Expected grandchild depth = 3, got %d", grandchildNode.Depth)
	}

	// Check parent-child relationships
	if len(grandparentNode.Children) != 2 {
		t.Errorf("Expected grandparent to have 2 children, got %d", len(grandparentNode.Children))
	}

	if len(parent1Node.Children) != 1 {
		t.Errorf("Expected parent1 to have 1 child, got %d", len(parent1Node.Children))
	}

	if len(child1Node.Children) != 1 {
		t.Errorf("Expected child1 to have 1 child, got %d", len(child1Node.Children))
	}

	if grandchildNode.HasChildren() {
		t.Error("Expected grandchild to have no children")
	}

	// Check flat list maintains tree order
	if len(tree.FlatList) != 5 {
		t.Fatalf("Expected 5 items in flat list, got %d", len(tree.FlatList))
	}

	// Grandparent should be first
	if tree.FlatList[0].Task.Uuid != "grandparent" {
		t.Errorf("Expected first item to be grandparent, got %s", tree.FlatList[0].Task.Uuid)
	}
}

func TestBuildTaskTree_OrphanedTask(t *testing.T) {
	tasks := Tasks{
		{Uuid: "task1", Description: "Normal Task", Status: "pending"},
		{
			Uuid:        "orphan",
			Description: "Orphaned Task",
			Status:      "pending",
			Udas:        map[string]any{"parenttask": "nonexistent"},
		},
	}

	tree := BuildTaskTree(tasks)

	if len(tree.Nodes) != 2 {
		t.Fatalf("Expected 2 nodes, got %d", len(tree.Nodes))
	}

	// Orphaned task should be treated as root
	if len(tree.Roots) != 2 {
		t.Errorf("Expected 2 roots (orphan should be treated as root), got %d", len(tree.Roots))
	}

	// Both should have depth 0
	for _, node := range tree.FlatList {
		if node.Depth != 0 {
			t.Errorf("Expected all tasks to have depth 0, got %d for %s", node.Depth, node.Task.Description)
		}
	}
}

func TestTaskNode_GetChildrenStatus(t *testing.T) {
	tests := []struct {
		name      string
		children  []*TaskNode
		wantComp  int
		wantTotal int
	}{
		{
			name:      "no children",
			children:  []*TaskNode{},
			wantComp:  0,
			wantTotal: 0,
		},
		{
			name: "all pending",
			children: []*TaskNode{
				{Task: &Task{Status: "pending"}},
				{Task: &Task{Status: "pending"}},
			},
			wantComp:  0,
			wantTotal: 2,
		},
		{
			name: "all completed",
			children: []*TaskNode{
				{Task: &Task{Status: "completed"}},
				{Task: &Task{Status: "completed"}},
				{Task: &Task{Status: "completed"}},
			},
			wantComp:  3,
			wantTotal: 3,
		},
		{
			name: "mixed status",
			children: []*TaskNode{
				{Task: &Task{Status: "completed"}},
				{Task: &Task{Status: "pending"}},
				{Task: &Task{Status: "completed"}},
				{Task: &Task{Status: "pending"}},
				{Task: &Task{Status: "completed"}},
			},
			wantComp:  3,
			wantTotal: 5,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			node := &TaskNode{
				Task:     &Task{},
				Children: tt.children,
			}

			gotComp, gotTotal := node.GetChildrenStatus()

			if gotComp != tt.wantComp {
				t.Errorf("GetChildrenStatus() completed = %d, want %d", gotComp, tt.wantComp)
			}
			if gotTotal != tt.wantTotal {
				t.Errorf("GetChildrenStatus() total = %d, want %d", gotTotal, tt.wantTotal)
			}
		})
	}
}

func TestTaskNode_HasChildren(t *testing.T) {
	tests := []struct {
		name     string
		children []*TaskNode
		want     bool
	}{
		{
			name:     "no children",
			children: []*TaskNode{},
			want:     false,
		},
		{
			name:     "has children",
			children: []*TaskNode{{Task: &Task{}}},
			want:     true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			node := &TaskNode{
				Task:     &Task{},
				Children: tt.children,
			}

			if got := node.HasChildren(); got != tt.want {
				t.Errorf("HasChildren() = %v, want %v", got, tt.want)
			}
		})
	}
}