"""
Unit tests for pipeline state management.

Tests cover state definitions, transition rules, and validation functions.
"""

import pytest

from src.core.states import PipelineState
from src.core.transitions import (
    is_transition_allowed,
    get_allowed_transitions,
    can_pause_from,
    can_resume_to,
    ALLOWED_TRANSITIONS,
)


class TestPipelineState:
    """Test PipelineState enum functionality."""

    def test_all_states_defined(self):
        """Test that all required states are defined."""
        required_states = {
            "IDLE",
            "FINGERPRINTING",
            "CLEANING",
            "TERM_EXTRACTION",
            "TRANSLATING",
            "UPLOADING",
            "PAUSED",
            "COMPLETED",
            "FAILED",
        }
        actual_states = {state.name for state in PipelineState}
        assert actual_states == required_states

    def test_state_values(self):
        """Test that state values are correct."""
        assert PipelineState.IDLE.value == "idle"
        assert PipelineState.FINGERPRINTING.value == "fingerprinting"
        assert PipelineState.CLEANING.value == "cleaning"
        assert PipelineState.TERM_EXTRACTION.value == "term_extraction"
        assert PipelineState.TRANSLATING.value == "translating"
        assert PipelineState.UPLOADING.value == "uploading"
        assert PipelineState.PAUSED.value == "paused"
        assert PipelineState.COMPLETED.value == "completed"
        assert PipelineState.FAILED.value == "failed"

    def test_is_terminal(self):
        """Test terminal state detection."""
        assert PipelineState.COMPLETED.is_terminal() is True
        assert PipelineState.FAILED.is_terminal() is True
        assert PipelineState.IDLE.is_terminal() is False
        assert PipelineState.TRANSLATING.is_terminal() is False

    def test_is_active(self):
        """Test active state detection."""
        active_states = {
            PipelineState.FINGERPRINTING,
            PipelineState.CLEANING,
            PipelineState.TERM_EXTRACTION,
            PipelineState.TRANSLATING,
            PipelineState.UPLOADING,
        }
        for state in active_states:
            assert state.is_active() is True

        inactive_states = {
            PipelineState.IDLE,
            PipelineState.PAUSED,
            PipelineState.COMPLETED,
            PipelineState.FAILED,
        }
        for state in inactive_states:
            assert state.is_active() is False

    def test_can_pause(self):
        """Test states from which pausing is allowed."""
        assert PipelineState.TRANSLATING.can_pause() is True
        assert PipelineState.CLEANING.can_pause() is True
        assert PipelineState.IDLE.can_pause() is False
        assert PipelineState.COMPLETED.can_pause() is False

    def test_can_resume(self):
        """Test states from which resuming is allowed."""
        assert PipelineState.PAUSED.can_resume() is True
        assert PipelineState.IDLE.can_resume() is False
        assert PipelineState.TRANSLATING.can_resume() is False


class TestStateTransitions:
    """Test state transition rules."""

    def test_idle_to_fingerprinting(self):
        """Test IDLE -> FINGERPRINTING transition."""
        assert is_transition_allowed(PipelineState.IDLE, PipelineState.FINGERPRINTING) is True

    def test_idle_to_other_states(self):
        """Test IDLE cannot transition to most states."""
        assert is_transition_allowed(PipelineState.IDLE, PipelineState.COMPLETED) is False
        assert is_transition_allowed(PipelineState.IDLE, PipelineState.TRANSLATING) is False
        assert is_transition_allowed(PipelineState.IDLE, PipelineState.FAILED) is False

    def test_normal_flow(self):
        """Test normal forward flow through the pipeline."""
        flow = [
            (PipelineState.IDLE, PipelineState.FINGERPRINTING),
            (PipelineState.FINGERPRINTING, PipelineState.CLEANING),
            (PipelineState.CLEANING, PipelineState.TERM_EXTRACTION),
            (PipelineState.TERM_EXTRACTION, PipelineState.TRANSLATING),
            (PipelineState.TRANSLATING, PipelineState.UPLOADING),
            (PipelineState.UPLOADING, PipelineState.COMPLETED),
        ]
        for from_state, to_state in flow:
            assert is_transition_allowed(from_state, to_state) is True, \
                f"Failed: {from_state} -> {to_state}"

    def test_failure_transitions(self):
        """Test transitions to FAILED state."""
        failure_sources = {
            PipelineState.FINGERPRINTING,
            PipelineState.CLEANING,
            PipelineState.TERM_EXTRACTION,
            PipelineState.TRANSLATING,
            PipelineState.UPLOADING,
        }
        for state in failure_sources:
            assert is_transition_allowed(state, PipelineState.FAILED) is True

    def test_pause_to_resume(self):
        """Test PAUSED can resume to active states."""
        assert is_transition_allowed(PipelineState.PAUSED, PipelineState.FINGERPRINTING) is True
        assert is_transition_allowed(PipelineState.PAUSED, PipelineState.TRANSLATING) is True
        assert is_transition_allowed(PipelineState.PAUSED, PipelineState.UPLOADING) is True

    def test_failed_to_idle(self):
        """Test FAILED can reset to IDLE."""
        assert is_transition_allowed(PipelineState.FAILED, PipelineState.IDLE) is True

    def test_completed_to_idle(self):
        """Test COMPLETED can reset to IDLE."""
        assert is_transition_allowed(PipelineState.COMPLETED, PipelineState.IDLE) is True

    def test_invalid_transitions(self):
        """Test some invalid transitions."""
        # Cannot skip states
        assert is_transition_allowed(PipelineState.IDLE, PipelineState.TRANSLATING) is False
        # Cannot go backwards (except via FAILED/COMPLETED -> IDLE)
        assert is_transition_allowed(PipelineState.TRANSLATING, PipelineState.CLEANING) is False
        # Cannot go from COMPLETED to active states directly
        assert is_transition_allowed(PipelineState.COMPLETED, PipelineState.TRANSLATING) is False


class TestTransitionHelpers:
    """Test helper functions for state transitions."""

    def test_get_allowed_transitions(self):
        """Test getting allowed transitions from a state."""
        allowed = get_allowed_transitions(PipelineState.IDLE)
        assert allowed == {PipelineState.FINGERPRINTING}

        allowed = get_allowed_transitions(PipelineState.TRANSLATING)
        assert PipelineState.UPLOADING in allowed
        assert PipelineState.FAILED in allowed
        assert PipelineState.CLEANING not in allowed

    def test_can_pause_from(self):
        """Test can_pause_from helper."""
        assert can_pause_from(PipelineState.TRANSLATING) is True
        assert can_pause_from(PipelineState.UPLOADING) is True
        assert can_pause_from(PipelineState.IDLE) is False
        assert can_pause_from(PipelineState.COMPLETED) is False

    def test_can_resume_to(self):
        """Test can_resume_to helper."""
        assert can_resume_to(PipelineState.TRANSLATING) is True
        assert can_resume_to(PipelineState.CLEANING) is True
        assert can_resume_to(PipelineState.COMPLETED) is False
        assert can_resume_to(PipelineState.FAILED) is False

    def test_allowed_transitions_completeness(self):
        """Test that all states have transition rules defined."""
        all_states = set(PipelineState)
        defined_states = set(ALLOWED_TRANSITIONS.keys())
        assert all_states == defined_states, \
            f"Missing transitions for: {all_states - defined_states}"


class TestTransitionEdgeCases:
    """Test edge cases in state transitions."""

    def test_same_state_transition(self):
        """Test that staying in same state is not a transition."""
        # Transitions to same state should not be explicitly allowed
        # (they're handled as "no transition needed")
        result = is_transition_allowed(PipelineState.IDLE, PipelineState.IDLE)
        # This should be False since we didn't define it
        assert result is False

    def test_all_states_can_reach_terminal(self):
        """Test that all active states can reach a terminal state."""
        active_states = {
            PipelineState.FINGERPRINTING,
            PipelineState.CLEANING,
            PipelineState.TERM_EXTRACTION,
            PipelineState.TRANSLATING,
            PipelineState.UPLOADING,
        }
        for state in active_states:
            # Can reach FAILED
            assert is_transition_allowed(state, PipelineState.FAILED), \
                f"{state} cannot reach FAILED"
            # Can reach COMPLETED via normal flow
            assert state == PipelineState.UPLOADING or \
                   any(is_transition_allowed(state, s) for s in PipelineState), \
                f"{state} cannot progress"