package maintenance

import (
	"testing"

	"github.com/seaweedfs/seaweedfs/weed/pb/worker_pb"
)

// Test suite for canScheduleTaskNow() function and related scheduling logic
//
// This test suite ensures that:
// 1. The fallback scheduling logic works correctly when no integration is present
// 2. Task concurrency limits are properly enforced per task type
// 3. Different task types don't interfere with each other's concurrency limits
// 4. Custom policies with higher concurrency limits work correctly
// 5. Edge cases (nil tasks, empty task types) are handled gracefully
// 6. Helper functions (GetRunningTaskCount, canExecuteTaskType, etc.) work correctly
//
// Background: The canScheduleTaskNow() function is critical for task assignment.
// It was previously failing due to an overly restrictive integration scheduler,
// so we implemented a temporary fix that bypasses the integration and uses
// fallback logic based on simple concurrency limits per task type.

func TestCanScheduleTaskNow_FallbackLogic(t *testing.T) {
	// Test the current implementation which uses fallback logic
	mq := &MaintenanceQueue{
		tasks:        make(map[string]*MaintenanceTask),
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
		policy:       nil, // No policy for default behavior
		integration:  nil, // No integration to force fallback
	}

	task := &MaintenanceTask{
		ID:     "test-task-1",
		Type:   MaintenanceTaskType("erasure_coding"),
		Status: TaskStatusPending,
	}

	// Should return true with fallback logic (no running tasks, default max concurrent = 1)
	result := mq.canScheduleTaskNow(task)
	if !result {
		t.Errorf("Expected canScheduleTaskNow to return true with fallback logic, got false")
	}
}

func TestCanScheduleTaskNow_FallbackWithRunningTasks(t *testing.T) {
	// Test fallback logic when there are already running tasks
	mq := &MaintenanceQueue{
		tasks: map[string]*MaintenanceTask{
			"running-task": {
				ID:     "running-task",
				Type:   MaintenanceTaskType("erasure_coding"),
				Status: TaskStatusInProgress,
			},
		},
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
		policy:       nil,
		integration:  nil,
	}

	task := &MaintenanceTask{
		ID:     "test-task-2",
		Type:   MaintenanceTaskType("erasure_coding"),
		Status: TaskStatusPending,
	}

	// Should return false because max concurrent is 1 and we have 1 running task
	result := mq.canScheduleTaskNow(task)
	if result {
		t.Errorf("Expected canScheduleTaskNow to return false when at capacity, got true")
	}
}

func TestCanScheduleTaskNow_DifferentTaskTypes(t *testing.T) {
	// Test that different task types don't interfere with each other
	mq := &MaintenanceQueue{
		tasks: map[string]*MaintenanceTask{
			"running-ec-task": {
				ID:     "running-ec-task",
				Type:   MaintenanceTaskType("erasure_coding"),
				Status: TaskStatusInProgress,
			},
		},
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
		policy:       nil,
		integration:  nil,
	}

	// Test vacuum task when EC task is running
	vacuumTask := &MaintenanceTask{
		ID:     "vacuum-task",
		Type:   MaintenanceTaskType("vacuum"),
		Status: TaskStatusPending,
	}

	// Should return true because vacuum and erasure_coding are different task types
	result := mq.canScheduleTaskNow(vacuumTask)
	if !result {
		t.Errorf("Expected canScheduleTaskNow to return true for different task type, got false")
	}

	// Test another EC task when one is already running
	ecTask := &MaintenanceTask{
		ID:     "ec-task",
		Type:   MaintenanceTaskType("erasure_coding"),
		Status: TaskStatusPending,
	}

	// Should return false because max concurrent for EC is 1 and we have 1 running
	result = mq.canScheduleTaskNow(ecTask)
	if result {
		t.Errorf("Expected canScheduleTaskNow to return false for same task type at capacity, got true")
	}
}

func TestCanScheduleTaskNow_WithIntegration(t *testing.T) {
	// Test with a real MaintenanceIntegration (will use fallback logic in current implementation)
	policy := &MaintenancePolicy{
		TaskPolicies:                 make(map[string]*worker_pb.TaskPolicy),
		GlobalMaxConcurrent:          10,
		DefaultRepeatIntervalSeconds: 24 * 60 * 60, // 24 hours in seconds
		DefaultCheckIntervalSeconds:  60 * 60,      // 1 hour in seconds
	}
	mq := NewMaintenanceQueue(policy)

	// Create a basic integration (this would normally be more complex)
	integration := NewMaintenanceIntegration(mq, policy)
	mq.SetIntegration(integration)

	task := &MaintenanceTask{
		ID:     "test-task-3",
		Type:   MaintenanceTaskType("erasure_coding"),
		Status: TaskStatusPending,
	}

	// With our current implementation (fallback logic), this should return true
	result := mq.canScheduleTaskNow(task)
	if !result {
		t.Errorf("Expected canScheduleTaskNow to return true with fallback logic, got false")
	}
}

func TestGetRunningTaskCount(t *testing.T) {
	// Test the helper function used by fallback logic
	mq := &MaintenanceQueue{
		tasks: map[string]*MaintenanceTask{
			"task1": {
				ID:     "task1",
				Type:   MaintenanceTaskType("erasure_coding"),
				Status: TaskStatusInProgress,
			},
			"task2": {
				ID:     "task2",
				Type:   MaintenanceTaskType("erasure_coding"),
				Status: TaskStatusAssigned,
			},
			"task3": {
				ID:     "task3",
				Type:   MaintenanceTaskType("vacuum"),
				Status: TaskStatusInProgress,
			},
			"task4": {
				ID:     "task4",
				Type:   MaintenanceTaskType("erasure_coding"),
				Status: TaskStatusCompleted,
			},
		},
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
	}

	// Should count 2 running EC tasks (in_progress + assigned)
	ecCount := mq.GetRunningTaskCount(MaintenanceTaskType("erasure_coding"))
	if ecCount != 2 {
		t.Errorf("Expected 2 running EC tasks, got %d", ecCount)
	}

	// Should count 1 running vacuum task
	vacuumCount := mq.GetRunningTaskCount(MaintenanceTaskType("vacuum"))
	if vacuumCount != 1 {
		t.Errorf("Expected 1 running vacuum task, got %d", vacuumCount)
	}

	// Should count 0 running balance tasks
	balanceCount := mq.GetRunningTaskCount(MaintenanceTaskType("balance"))
	if balanceCount != 0 {
		t.Errorf("Expected 0 running balance tasks, got %d", balanceCount)
	}
}

func TestCanExecuteTaskType(t *testing.T) {
	// Test the fallback logic helper function
	mq := &MaintenanceQueue{
		tasks: map[string]*MaintenanceTask{
			"running-task": {
				ID:     "running-task",
				Type:   MaintenanceTaskType("erasure_coding"),
				Status: TaskStatusInProgress,
			},
		},
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
		policy:       nil, // Will use default max concurrent = 1
		integration:  nil,
	}

	// Should return false for EC (1 running, max = 1)
	result := mq.canExecuteTaskType(MaintenanceTaskType("erasure_coding"))
	if result {
		t.Errorf("Expected canExecuteTaskType to return false for EC at capacity, got true")
	}

	// Should return true for vacuum (0 running, max = 1)
	result = mq.canExecuteTaskType(MaintenanceTaskType("vacuum"))
	if !result {
		t.Errorf("Expected canExecuteTaskType to return true for vacuum, got false")
	}
}

func TestGetMaxConcurrentForTaskType_DefaultBehavior(t *testing.T) {
	// Test the default behavior when no policy or integration is set
	mq := &MaintenanceQueue{
		tasks:        make(map[string]*MaintenanceTask),
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
		policy:       nil,
		integration:  nil,
	}

	// Should return default value of 1
	maxConcurrent := mq.getMaxConcurrentForTaskType(MaintenanceTaskType("erasure_coding"))
	if maxConcurrent != 1 {
		t.Errorf("Expected default max concurrent to be 1, got %d", maxConcurrent)
	}

	maxConcurrent = mq.getMaxConcurrentForTaskType(MaintenanceTaskType("vacuum"))
	if maxConcurrent != 1 {
		t.Errorf("Expected default max concurrent to be 1, got %d", maxConcurrent)
	}
}

// Test edge cases and error conditions
func TestCanScheduleTaskNow_NilTask(t *testing.T) {
	mq := &MaintenanceQueue{
		tasks:        make(map[string]*MaintenanceTask),
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
		policy:       nil,
		integration:  nil,
	}

	// This should panic with a nil task, so we expect and catch the panic
	defer func() {
		if r := recover(); r == nil {
			t.Errorf("Expected canScheduleTaskNow to panic with nil task, but it didn't")
		}
	}()

	// This should panic
	mq.canScheduleTaskNow(nil)
}

func TestCanScheduleTaskNow_EmptyTaskType(t *testing.T) {
	mq := &MaintenanceQueue{
		tasks:        make(map[string]*MaintenanceTask),
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
		policy:       nil,
		integration:  nil,
	}

	task := &MaintenanceTask{
		ID:     "empty-type-task",
		Type:   MaintenanceTaskType(""), // Empty task type
		Status: TaskStatusPending,
	}

	// Should handle empty task type gracefully
	result := mq.canScheduleTaskNow(task)
	if !result {
		t.Errorf("Expected canScheduleTaskNow to handle empty task type, got false")
	}
}

func TestCanScheduleTaskNow_WithPolicy(t *testing.T) {
	// Test with a policy that allows higher concurrency
	policy := &MaintenancePolicy{
		TaskPolicies: map[string]*worker_pb.TaskPolicy{
			string(MaintenanceTaskType("erasure_coding")): {
				Enabled:               true,
				MaxConcurrent:         3,
				RepeatIntervalSeconds: 60 * 60, // 1 hour
				CheckIntervalSeconds:  60 * 60, // 1 hour
			},
			string(MaintenanceTaskType("vacuum")): {
				Enabled:               true,
				MaxConcurrent:         2,
				RepeatIntervalSeconds: 60 * 60, // 1 hour
				CheckIntervalSeconds:  60 * 60, // 1 hour
			},
		},
		GlobalMaxConcurrent:          10,
		DefaultRepeatIntervalSeconds: 24 * 60 * 60, // 24 hours in seconds
		DefaultCheckIntervalSeconds:  60 * 60,      // 1 hour in seconds
	}

	mq := &MaintenanceQueue{
		tasks: map[string]*MaintenanceTask{
			"running-task-1": {
				ID:     "running-task-1",
				Type:   MaintenanceTaskType("erasure_coding"),
				Status: TaskStatusInProgress,
			},
			"running-task-2": {
				ID:     "running-task-2",
				Type:   MaintenanceTaskType("erasure_coding"),
				Status: TaskStatusAssigned,
			},
		},
		pendingTasks: []*MaintenanceTask{},
		workers:      make(map[string]*MaintenanceWorker),
		policy:       policy,
		integration:  nil,
	}

	task := &MaintenanceTask{
		ID:     "test-task-policy",
		Type:   MaintenanceTaskType("erasure_coding"),
		Status: TaskStatusPending,
	}

	// Should return true because we have 2 running EC tasks but max is 3
	result := mq.canScheduleTaskNow(task)
	if !result {
		t.Errorf("Expected canScheduleTaskNow to return true with policy allowing 3 concurrent, got false")
	}

	// Add one more running task to reach the limit
	mq.tasks["running-task-3"] = &MaintenanceTask{
		ID:     "running-task-3",
		Type:   MaintenanceTaskType("erasure_coding"),
		Status: TaskStatusInProgress,
	}

	// Should return false because we now have 3 running EC tasks (at limit)
	result = mq.canScheduleTaskNow(task)
	if result {
		t.Errorf("Expected canScheduleTaskNow to return false when at policy limit, got true")
	}
}