"""
Error recovery integration tests.

Tests cover:
- Error detection and classification
- Retry mechanisms with backoff
- Circuit breaker pattern
- Graceful degradation
- Partial result preservation
- Transaction rollback
- Resource cleanup on failure
"""

import time
import threading
from datetime import datetime


class TestErrorDetection:
    """Tests for error detection."""

    def test_llm_error_detected(self):
        """LLM errors should be detected and classified."""

        def classify_error(error):
            error_str = str(error).lower()
            if "connection" in error_str:
                return "connection_error"
            if "rate limit" in error_str or "429" in error_str:
                return "rate_limit"
            if "timeout" in error_str:
                return "timeout"
            if "model not found" in error_str or "404" in error_str:
                return "model_not_found"
            return "unknown"

        assert classify_error("Connection refused") == "connection_error"
        assert classify_error("Rate limit exceeded 429") == "rate_limit"
        assert classify_error("Request timeout") == "timeout"
        assert classify_error("Model not found 404") == "model_not_found"

    def test_database_error_detected(self):
        """Database errors should be detected."""

        def is_database_error(error):
            db_indicators = [
                "database",
                "sqlite",
                "sqlalchemy",
                "connection pool",
                "integrity",
                "constraint",
            ]
            error_str = str(error).lower()
            return any(ind in error_str for ind in db_indicators)

        assert is_database_error("SQLAlchemy connection error") is True
        assert is_database_error("Database connection pool exhausted") is True
        assert is_database_error("Network timeout") is False

    def test_transient_vs_permanent_error(self):
        """Should distinguish transient from permanent errors."""

        def is_transient(error):
            transient_indicators = [
                "timeout",
                "rate limit",
                "connection",
                "unavailable",
                "503",
                "429",
                "temporary",
            ]
            error_str = str(error).lower()
            return any(ind in error_str for ind in transient_indicators)

        assert is_transient("Service temporarily unavailable 503") is True
        assert is_transient("Connection timeout") is True
        assert is_transient("Invalid API key") is False
        assert is_transient("Model not found") is False


class TestRetryMechanisms:
    """Tests for retry mechanisms."""

    def test_simple_retry(self):
        """Simple retry should work for transient errors."""
        attempts = []
        max_retries = 3

        def operation_with_retry():
            for attempt in range(max_retries):
                attempts.append(attempt)
                try:
                    if attempt < 2:
                        raise ConnectionError("Transient failure")
                    return "success"
                except ConnectionError:
                    if attempt == max_retries - 1:
                        raise
                    continue

        result = operation_with_retry()
        assert result == "success"
        assert len(attempts) == 3

    def test_exponential_backoff(self):
        """Exponential backoff should increase wait times."""
        base_delay = 0.1
        max_delay = 2.0

        def calculate_delay(attempt, base=base_delay, max_d=max_delay):
            delay = base * (2**attempt)
            return min(delay, max_d)

        delays = [calculate_delay(i) for i in range(5)]

        assert delays[0] == 0.1
        assert delays[1] == 0.2
        assert delays[2] == 0.4
        assert delays[4] <= max_delay

    def test_retry_with_jitter(self):
        """Retry with jitter should add randomness."""
        import random

        def calculate_delay_with_jitter(attempt, base=0.1):
            delay = base * (2**attempt)
            jitter = random.uniform(0, delay * 0.1)  # 10% jitter
            return delay + jitter

        # Multiple calculations should differ
        delays = [calculate_delay_with_jitter(2) for _ in range(10)]
        unique_delays = set(delays)
        assert len(unique_delays) > 1

    def test_retry_budget_enforced(self):
        """Retry budget should be enforced."""
        max_total_retries = 10
        retry_counts = {}

        def attempt_with_budget(operation_id):
            if operation_id not in retry_counts:
                retry_counts[operation_id] = 0

            if retry_counts[operation_id] >= 3:  # Per-operation limit
                return False, "operation_limit"

            total = sum(retry_counts.values())
            if total >= max_total_retries:
                return False, "budget_exceeded"

            retry_counts[operation_id] += 1
            return True, None

        # Exhaust budget
        for op in ["op1", "op2", "op3", "op4"]:
            for _ in range(3):
                attempt_with_budget(op)

        # Budget should be exceeded
        can_retry, reason = attempt_with_budget("op5")
        assert can_retry is False
        assert reason == "budget_exceeded"


class TestCircuitBreaker:
    """Tests for circuit breaker pattern."""

    def test_circuit_opens_after_failures(self):
        """Circuit should open after consecutive failures."""
        circuit = {
            "state": "closed",
            "failures": 0,
            "failure_threshold": 3,
            "last_failure": None,
        }

        def record_failure():
            circuit["failures"] += 1
            circuit["last_failure"] = time.time()
            if circuit["failures"] >= circuit["failure_threshold"]:
                circuit["state"] = "open"

        def record_success():
            circuit["failures"] = 0
            circuit["state"] = "closed"

        def can_execute():
            return circuit["state"] != "open"

        # Record failures
        for _ in range(3):
            record_failure()

        assert circuit["state"] == "open"
        assert can_execute() is False

    def test_circuit_half_open_after_timeout(self):
        """Circuit should become half-open after timeout."""
        circuit = {
            "state": "open",
            "opened_at": time.time() - 35,  # 35 seconds ago
            "timeout": 30,  # 30 second timeout
        }

        def check_state():
            if circuit["state"] == "open":
                if time.time() - circuit["opened_at"] > circuit["timeout"]:
                    circuit["state"] = "half-open"
            return circuit["state"]

        assert check_state() == "half-open"

    def test_circuit_closes_on_success(self):
        """Circuit should close after successful call in half-open."""
        circuit = {"state": "half-open", "failures": 3}

        def record_success():
            if circuit["state"] == "half-open":
                circuit["state"] = "closed"
                circuit["failures"] = 0

        record_success()

        assert circuit["state"] == "closed"
        assert circuit["failures"] == 0


class TestGracefulDegradation:
    """Tests for graceful degradation."""

    def test_fallback_to_cached_data(self):
        """Should fall back to cached data on error."""
        cache = {
            "query_hash": {"result": "cached_result", "timestamp": time.time()}
        }

        def get_result(query_hash, fetch_func):
            try:
                return fetch_func()
            except Exception:
                if query_hash in cache:
                    return cache[query_hash]["result"]
                raise

        def failing_fetch():
            raise ConnectionError("Service unavailable")

        result = get_result("query_hash", failing_fetch)
        assert result == "cached_result"

    def test_reduced_functionality_mode(self):
        """Should operate in reduced functionality mode."""
        services = {
            "llm": {"available": False, "required": True},
            "search": {"available": True, "required": True},
            "cache": {"available": False, "required": False},
        }

        def get_available_mode():
            required_available = all(
                s["available"] for s in services.values() if s["required"]
            )
            if not required_available:
                return "degraded"
            return "full"

        assert get_available_mode() == "degraded"

    def test_alternative_provider_selection(self):
        """Should select alternative provider on failure."""
        providers = [
            {"name": "primary", "available": False},
            {"name": "secondary", "available": True},
            {"name": "tertiary", "available": True},
        ]

        def get_available_provider():
            for provider in providers:
                if provider["available"]:
                    return provider["name"]
            return None

        assert get_available_provider() == "secondary"


class TestPartialResultPreservation:
    """Tests for partial result preservation."""

    def test_partial_results_saved_on_error(self):
        """Partial results should be saved when error occurs."""
        partial_results = []
        error_occurred = None

        def process_with_checkpointing(items):
            nonlocal error_occurred
            for i, item in enumerate(items):
                try:
                    if i == 3:
                        raise Exception("Processing failed")
                    partial_results.append(f"processed_{item}")
                except Exception as e:
                    error_occurred = str(e)
                    break

        process_with_checkpointing(["a", "b", "c", "d", "e"])

        assert len(partial_results) == 3
        assert error_occurred is not None

    def test_checkpoint_restoration(self):
        """Should be able to restore from checkpoint."""
        checkpoint = {
            "last_processed_index": 5,
            "partial_results": ["r0", "r1", "r2", "r3", "r4"],
            "state": {"analysis_complete": True},
        }

        def restore_from_checkpoint(checkpoint):
            return {
                "resume_index": checkpoint["last_processed_index"],
                "results": list(checkpoint["partial_results"]),
                "state": dict(checkpoint["state"]),
            }

        restored = restore_from_checkpoint(checkpoint)

        assert restored["resume_index"] == 5
        assert len(restored["results"]) == 5

    def test_incremental_save(self):
        """Results should be saved incrementally."""
        save_log = []

        def save_result(result_id, data):
            save_log.append(
                {"id": result_id, "data": data, "time": time.time()}
            )

        # Simulate incremental saves during processing
        for i in range(5):
            save_result(f"result_{i}", f"data_{i}")

        assert len(save_log) == 5


class TestTransactionRollback:
    """Tests for transaction rollback."""

    def test_rollback_on_error(self):
        """Transaction should rollback on error."""
        database = {"committed": [], "pending": []}

        def transaction(operations):
            database["pending"] = []
            try:
                for op in operations:
                    if op == "fail":
                        raise Exception("Operation failed")
                    database["pending"].append(op)
                # Commit
                database["committed"].extend(database["pending"])
            except Exception:
                # Rollback
                database["pending"] = []
                raise

        try:
            transaction(["op1", "op2", "fail", "op4"])
        except Exception:
            pass

        assert "op1" not in database["committed"]
        assert len(database["pending"]) == 0

    def test_partial_commit_prevention(self):
        """Should prevent partial commits."""
        state = {"phase1": False, "phase2": False, "phase3": False}

        def atomic_update(updates):
            backup = dict(state)
            try:
                for key, value in updates.items():
                    if key == "phase2" and value:
                        raise Exception("Phase 2 failed")
                    state[key] = value
            except Exception:
                # Restore backup
                state.clear()
                state.update(backup)
                raise

        try:
            atomic_update({"phase1": True, "phase2": True, "phase3": True})
        except Exception:
            pass

        assert state == {"phase1": False, "phase2": False, "phase3": False}


class TestResourceCleanup:
    """Tests for resource cleanup on failure."""

    def test_cleanup_on_exception(self):
        """Resources should be cleaned up on exception."""
        resources = {"allocated": [], "cleaned": []}

        def allocate(name):
            resources["allocated"].append(name)
            return name

        def cleanup(name):
            if name in resources["allocated"]:
                resources["allocated"].remove(name)
                resources["cleaned"].append(name)

        def operation_with_cleanup():
            r1 = allocate("resource1")
            r2 = allocate("resource2")
            try:
                raise Exception("Operation failed")
            finally:
                cleanup(r1)
                cleanup(r2)

        try:
            operation_with_cleanup()
        except Exception:
            pass

        assert len(resources["allocated"]) == 0
        assert len(resources["cleaned"]) == 2

    def test_context_manager_cleanup(self):
        """Context managers should ensure cleanup."""

        class Resource:
            instances = []
            cleaned = []

            def __init__(self, name):
                self.name = name
                Resource.instances.append(name)

            def __enter__(self):
                return self

            def __exit__(self, exc_type, exc_val, exc_tb):
                Resource.instances.remove(self.name)
                Resource.cleaned.append(self.name)
                return False  # Don't suppress exception

        try:
            with Resource("r1"):
                with Resource("r2"):
                    raise Exception("Error")
        except Exception:
            pass

        assert len(Resource.instances) == 0
        assert len(Resource.cleaned) == 2

    def test_thread_cleanup_on_failure(self):
        """Threads should be cleaned up on failure."""
        threads_started = []
        threads_stopped = []
        stop_event = threading.Event()

        def worker(name):
            threads_started.append(name)
            while not stop_event.is_set():
                time.sleep(0.01)
            threads_stopped.append(name)

        threads = []
        for i in range(3):
            t = threading.Thread(target=worker, args=(f"worker_{i}",))
            t.start()
            threads.append(t)

        # Simulate failure - signal stop
        stop_event.set()

        for t in threads:
            t.join(timeout=1)

        assert len(threads_stopped) == 3


class TestErrorReporting:
    """Tests for error reporting."""

    def test_error_context_captured(self):
        """Error context should be captured."""

        def capture_error_context(error, context):
            return {
                "error_type": type(error).__name__,
                "error_message": str(error),
                "timestamp": datetime.now().isoformat(),
                "context": context,
            }

        error = ValueError("Invalid input")
        report = capture_error_context(
            error, {"phase": "analysis", "query": "test query"}
        )

        assert report["error_type"] == "ValueError"
        assert "context" in report
        assert report["context"]["phase"] == "analysis"

    def test_error_chain_preserved(self):
        """Error chain should be preserved."""

        def inner_operation():
            raise ValueError("Inner error")

        def outer_operation():
            try:
                inner_operation()
            except ValueError as e:
                raise RuntimeError("Outer error") from e

        try:
            outer_operation()
        except RuntimeError as e:
            assert e.__cause__ is not None
            assert "Inner error" in str(e.__cause__)


class TestRecoveryStrategies:
    """Tests for recovery strategies."""

    def test_automatic_recovery_attempt(self):
        """Should attempt automatic recovery."""
        recovery_attempts = []

        def attempt_recovery(error_type):
            recovery_attempts.append(error_type)
            recovery_actions = {
                "connection_error": "reconnect",
                "rate_limit": "wait_and_retry",
                "timeout": "increase_timeout",
            }
            return recovery_actions.get(error_type, "manual_intervention")

        action = attempt_recovery("connection_error")
        assert action == "reconnect"
        assert len(recovery_attempts) == 1

    def test_recovery_escalation(self):
        """Recovery should escalate if initial attempts fail."""
        escalation_levels = []

        def recover_with_escalation(error, max_levels=3):
            for level in range(max_levels):
                escalation_levels.append(level)
                if level == 2:  # Succeed on level 2
                    return True
            return False

        success = recover_with_escalation(Exception("test"))
        assert success is True
        assert escalation_levels == [0, 1, 2]

    def test_recovery_timeout(self):
        """Recovery should timeout if taking too long."""
        start_time = time.time()
        max_recovery_time = 0.1

        def recover_with_timeout():
            while time.time() - start_time < max_recovery_time:
                time.sleep(0.02)
                # Simulate recovery attempt
                if time.time() - start_time > max_recovery_time / 2:
                    return True  # Recovered in time
            return False  # Timed out

        result = recover_with_timeout()
        assert result is True
