import pytest
from models import Ticket
from dag_engine import TrackDAG, ExecutionEngine

def test_execution_engine_basic_flow():
    # Setup tickets with dependencies
    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")
    t2 = Ticket(id="T2", description="Task 2", status="todo", assigned_to="worker", depends_on=["T1"])
    t3 = Ticket(id="T3", description="Task 3", status="todo", assigned_to="worker", depends_on=["T1"])
    t4 = Ticket(id="T4", description="Task 4", status="todo", assigned_to="worker", depends_on=["T2", "T3"])

    dag = TrackDAG([t1, t2, t3, t4])
    engine = ExecutionEngine(dag)

    # Tick 1: Only T1 should be ready
    ready = engine.tick()
    assert len(ready) == 1
    assert ready[0].id == "T1"

    # Complete T1
    engine.update_task_status("T1", "completed")

    # Tick 2: T2 and T3 should be ready
    ready = engine.tick()
    assert len(ready) == 2
    ids = {t.id for t in ready}
    assert ids == {"T2", "T3"}

    # Complete T2
    engine.update_task_status("T2", "completed")

    # Tick 3: Only T3 should be ready (T4 depends on T2 AND T3)
    ready = engine.tick()
    assert len(ready) == 1
    assert ready[0].id == "T3"

    # Complete T3
    engine.update_task_status("T3", "completed")

    # Tick 4: T4 should be ready
    ready = engine.tick()
    assert len(ready) == 1
    assert ready[0].id == "T4"

    # Complete T4
    engine.update_task_status("T4", "completed")

    # Tick 5: Nothing ready
    ready = engine.tick()
    assert len(ready) == 0

def test_execution_engine_update_nonexistent_task():
    dag = TrackDAG([])
    engine = ExecutionEngine(dag)
    # Should not raise error, or handle gracefully
    engine.update_task_status("NONEXISTENT", "completed")

def test_execution_engine_status_persistence():
    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")
    dag = TrackDAG([t1])
    engine = ExecutionEngine(dag)
    
    engine.update_task_status("T1", "in_progress")
    assert t1.status == "in_progress"
    
    ready = engine.tick()
    assert len(ready) == 0 # Only 'todo' tasks should be returned by tick() if they are ready

def test_execution_engine_auto_queue():
    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")
    t2 = Ticket(id="T2", description="Task 2", status="todo", assigned_to="worker", depends_on=["T1"])
    
    dag = TrackDAG([t1, t2])
    engine = ExecutionEngine(dag, auto_queue=True)
    
    # Tick 1: T1 is ready and should be automatically marked as 'in_progress'
    ready = engine.tick()
    assert len(ready) == 1
    assert ready[0].id == "T1"
    assert t1.status == "in_progress"
    
    # Tick 2: T1 is in_progress, so T2 is NOT ready yet (T1 must be 'completed')
    ready = engine.tick()
    assert len(ready) == 0
    assert t2.status == "todo"
    
    # Complete T1
    engine.update_task_status("T1", "completed")
    
    # Tick 3: T2 is now ready and should be automatically marked as 'in_progress'
    ready = engine.tick()
    assert len(ready) == 1
    assert ready[0].id == "T2"
    assert t2.status == "in_progress"

def test_execution_engine_step_mode():
    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker", step_mode=True)
    
    dag = TrackDAG([t1])
    engine = ExecutionEngine(dag, auto_queue=True)
    
    # Tick 1: T1 is ready, but step_mode=True, so it should NOT be automatically marked as 'in_progress'
    ready = engine.tick()
    assert len(ready) == 1
    assert ready[0].id == "T1"
    assert t1.status == "todo"
    
    # Manual approval
    engine.approve_task("T1")
    assert t1.status == "in_progress"
    
    # Tick 2: T1 is already in_progress, should not be returned by tick() (it's not 'ready'/todo)
    ready = engine.tick()
    assert len(ready) == 0

def test_execution_engine_approve_task():
    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")
    dag = TrackDAG([t1])
    engine = ExecutionEngine(dag, auto_queue=False)
    
    # Should be able to approve even if auto_queue is False
    engine.approve_task("T1")
    assert t1.status == "in_progress"