"""
Unit tests for Tree-of-Thoughts Agent (TDD Approach - Tests Written First)

Pattern: "Explore Multiple Paths" - Generate, evaluate, select best reasoning path

Test Coverage:
- 15 unit tests total
- Path generation: 4 tests (single, multiple, parallel, errors)
- Path evaluation: 4 tests (scoring, model selection, errors, timeout)
- Path selection: 3 tests (best path, tie-breaking, all fail)
- Execution: 2 tests (best path execution, fallback)
- Configuration: 2 tests (defaults, custom values)

Test Structure (TDD):
1. Write ALL tests first (they should fail)
2. Implement minimal code to make tests pass
3. Refactor if needed
4. Verify all existing tests still pass

Expected test execution time: <1 second per test (Tier 1)
"""

import pytest

# Import agent components (will be implemented after tests)
try:
    from kaizen.agents.specialized.tree_of_thoughts import ToTAgent, ToTAgentConfig
except ImportError:
    pytest.skip("ToT agent not yet implemented", allow_module_level=True)


# ============================================================================
# PATH GENERATION TESTS (4 tests)
# ============================================================================


def test_generate_single_path():
    """Test generation of single reasoning path"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=1,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Simple decision task")

    # Verify single path generated
    assert "paths" in result
    assert isinstance(result["paths"], list)
    assert len(result["paths"]) == 1


def test_generate_multiple_paths():
    """Test generation of multiple reasoning paths"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=5,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Complex decision task")

    # Verify multiple paths generated
    assert "paths" in result
    assert len(result["paths"]) == 5

    # Each path should have structure
    for path in result["paths"]:
        assert isinstance(path, dict)
        assert "reasoning" in path or "steps" in path


def test_parallel_path_generation():
    """Test parallel path generation (when enabled)"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=5,
        parallel_execution=True,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Task requiring parallel paths")

    # Should generate paths (parallel or sequential)
    assert "paths" in result
    assert len(result["paths"]) > 0


def test_path_generation_with_errors():
    """Test path generation error handling"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=3,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Task that may cause errors")

    # Should handle errors gracefully
    assert "paths" in result or "error" in result


# ============================================================================
# PATH EVALUATION TESTS (4 tests)
# ============================================================================


def test_path_evaluation_scoring():
    """Test path evaluation and scoring"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=3,
        evaluation_criteria="quality",
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Decision task")

    # Verify evaluation results
    assert "evaluations" in result
    assert isinstance(result["evaluations"], list)

    # Each evaluation should have score
    for evaluation in result["evaluations"]:
        assert "score" in evaluation
        assert isinstance(evaluation["score"], (int, float))
        assert 0 <= evaluation["score"] <= 1


def test_evaluation_criteria_selection():
    """Test different evaluation criteria"""
    criteria_list = ["quality", "speed", "creativity"]

    for criteria in criteria_list:
        config = ToTAgentConfig(
            llm_provider="mock",
            model="mock-model",
            num_paths=2,
            evaluation_criteria=criteria,
        )
        agent = ToTAgent(config=config)
        result = agent.run(task="Test task")

        # Should have evaluations
        assert "evaluations" in result


def test_evaluation_with_errors():
    """Test evaluation error handling"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=3,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Task with evaluation challenges")

    # Should handle evaluation errors
    assert "evaluations" in result or "error" in result


def test_evaluation_timeout_handling():
    """Test evaluation timeout handling"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=2,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Task requiring evaluation")

    # Should complete evaluation (with timeout protection)
    assert "evaluations" in result


# ============================================================================
# PATH SELECTION TESTS (3 tests)
# ============================================================================


def test_best_path_selection():
    """Test selection of best path based on score"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=5,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Multi-path decision")

    # Verify best path selected
    assert "best_path" in result
    assert isinstance(result["best_path"], dict)
    assert "score" in result["best_path"]

    # Best path should have highest score
    if len(result["evaluations"]) > 1:
        best_score = result["best_path"]["score"]
        all_scores = [eval["score"] for eval in result["evaluations"]]
        assert best_score == max(all_scores)


def test_tie_breaking_equal_scores():
    """Test tie-breaking when multiple paths have equal scores"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=3,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Task with similar paths")

    # Should select a path even with ties
    assert "best_path" in result
    assert isinstance(result["best_path"], dict)


def test_all_paths_fail_fallback():
    """Test fallback when all paths fail"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=3,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Challenging task")

    # Should handle all paths failing
    if "error" in result:
        assert isinstance(result["error"], str)
    else:
        # Should select best available path despite failures
        assert "best_path" in result


# ============================================================================
# EXECUTION TESTS (2 tests)
# ============================================================================


def test_best_path_execution():
    """Test execution of best path"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=3,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Task to execute")

    # Verify execution results
    assert "final_result" in result
    assert isinstance(result["final_result"], str)


def test_execution_error_fallback():
    """Test fallback when best path execution fails"""
    config = ToTAgentConfig(
        llm_provider="mock",
        model="mock-model",
        num_paths=3,
    )
    agent = ToTAgent(config=config)

    result = agent.run(task="Task with execution risk")

    # Should handle execution errors
    assert "final_result" in result or "error" in result


# ============================================================================
# CONFIGURATION TESTS (2 tests)
# ============================================================================


def test_tot_config_defaults():
    """Test ToTAgentConfig default values"""
    config = ToTAgentConfig()

    # Verify default values
    assert config.llm_provider == "openai"
    assert config.model == "gpt-4"
    assert config.temperature == 0.9  # Higher for diversity
    assert config.num_paths == 5
    assert config.max_paths == 20
    assert config.evaluation_criteria == "quality"
    assert config.parallel_execution is True


def test_tot_config_custom_values():
    """Test ToTAgentConfig with custom values"""
    config = ToTAgentConfig(
        llm_provider="anthropic",
        model="claude-3-opus",
        temperature=0.8,
        num_paths=10,
        max_paths=15,
        evaluation_criteria="creativity",
        parallel_execution=False,
    )

    # Verify custom values
    assert config.llm_provider == "anthropic"
    assert config.model == "claude-3-opus"
    assert config.temperature == 0.8
    assert config.num_paths == 10
    assert config.max_paths == 15
    assert config.evaluation_criteria == "creativity"
    assert config.parallel_execution is False
