"""
Deep behavioral tests for async operation patterns.
Tests queue management, task scheduling, promise patterns,
and concurrent operation logic.
"""

from datetime import datetime, timezone, timedelta
from collections import deque


# --- Queue management patterns ---


class TestQueueManagement:
    """Tests for queue management patterns."""

    def _create_queue(self, max_size=None):
        """Create a queue."""
        return {
            "items": deque(maxlen=max_size),
            "max_size": max_size,
        }

    def _enqueue(self, queue, item):
        """Add item to queue."""
        if queue["max_size"] and len(queue["items"]) >= queue["max_size"]:
            return False
        queue["items"].append(item)
        return True

    def _dequeue(self, queue):
        """Remove and return item from queue."""
        if not queue["items"]:
            return None
        return queue["items"].popleft()

    def _peek(self, queue):
        """View next item without removing."""
        if not queue["items"]:
            return None
        return queue["items"][0]

    def _is_empty(self, queue):
        """Check if queue is empty."""
        return len(queue["items"]) == 0

    def test_enqueue_adds_item(self):
        queue = self._create_queue()
        self._enqueue(queue, "item1")
        assert len(queue["items"]) == 1

    def test_dequeue_removes_item(self):
        queue = self._create_queue()
        self._enqueue(queue, "item1")
        result = self._dequeue(queue)
        assert result == "item1"
        assert self._is_empty(queue)

    def test_fifo_order(self):
        queue = self._create_queue()
        self._enqueue(queue, "first")
        self._enqueue(queue, "second")
        assert self._dequeue(queue) == "first"
        assert self._dequeue(queue) == "second"

    def test_max_size_enforced(self):
        queue = self._create_queue(max_size=2)
        self._enqueue(queue, "1")
        self._enqueue(queue, "2")
        result = self._enqueue(queue, "3")
        assert result is False

    def test_peek_doesnt_remove(self):
        queue = self._create_queue()
        self._enqueue(queue, "item")
        peeked = self._peek(queue)
        assert peeked == "item"
        assert not self._is_empty(queue)


class TestPriorityQueue:
    """Tests for priority queue patterns."""

    def _create_priority_queue(self):
        """Create a priority queue."""
        return {"items": []}

    def _enqueue_priority(self, pq, item, priority):
        """Add item with priority (lower = higher priority)."""
        entry = {"item": item, "priority": priority}
        pq["items"].append(entry)
        pq["items"].sort(key=lambda x: x["priority"])

    def _dequeue_priority(self, pq):
        """Remove and return highest priority item."""
        if not pq["items"]:
            return None
        return pq["items"].pop(0)["item"]

    def test_priority_order(self):
        pq = self._create_priority_queue()
        self._enqueue_priority(pq, "low", 10)
        self._enqueue_priority(pq, "high", 1)
        self._enqueue_priority(pq, "medium", 5)
        assert self._dequeue_priority(pq) == "high"
        assert self._dequeue_priority(pq) == "medium"
        assert self._dequeue_priority(pq) == "low"


# --- Task scheduling patterns ---


class TestTaskScheduling:
    """Tests for task scheduling patterns."""

    def _create_task(self, task_id, execute_at=None, priority=0):
        """Create a scheduled task."""
        return {
            "id": task_id,
            "execute_at": execute_at or datetime.now(timezone.utc),
            "priority": priority,
            "status": "pending",
            "created_at": datetime.now(timezone.utc),
        }

    def _is_due(self, task):
        """Check if task is due for execution."""
        return task["execute_at"] <= datetime.now(timezone.utc)

    def _get_due_tasks(self, tasks):
        """Get all tasks that are due."""
        return [
            t for t in tasks if self._is_due(t) and t["status"] == "pending"
        ]

    def _schedule_task(self, tasks, task_id, delay_seconds):
        """Schedule a new task with delay."""
        execute_at = datetime.now(timezone.utc) + timedelta(
            seconds=delay_seconds
        )
        task = self._create_task(task_id, execute_at)
        tasks.append(task)
        return task

    def test_task_creation(self):
        task = self._create_task("task-1")
        assert task["id"] == "task-1"
        assert task["status"] == "pending"

    def test_is_due_immediate(self):
        task = self._create_task("task-1")
        assert self._is_due(task) is True

    def test_is_due_future(self):
        future = datetime.now(timezone.utc) + timedelta(hours=1)
        task = self._create_task("task-1", execute_at=future)
        assert self._is_due(task) is False

    def test_get_due_tasks(self):
        now = datetime.now(timezone.utc)
        past = now - timedelta(hours=1)
        future = now + timedelta(hours=1)
        tasks = [
            self._create_task("1", execute_at=past),
            self._create_task("2", execute_at=future),
            self._create_task("3", execute_at=past),
        ]
        due = self._get_due_tasks(tasks)
        assert len(due) == 2


class TestRecurringTasks:
    """Tests for recurring task patterns."""

    def _create_recurring_task(self, task_id, interval_seconds):
        """Create a recurring task."""
        return {
            "id": task_id,
            "interval_seconds": interval_seconds,
            "last_run": None,
            "next_run": datetime.now(timezone.utc),
            "run_count": 0,
        }

    def _calculate_next_run(self, task):
        """Calculate next run time."""
        return datetime.now(timezone.utc) + timedelta(
            seconds=task["interval_seconds"]
        )

    def _mark_executed(self, task):
        """Mark task as executed and schedule next run."""
        task["last_run"] = datetime.now(timezone.utc)
        task["next_run"] = self._calculate_next_run(task)
        task["run_count"] += 1
        return task

    def _is_overdue(self, task, threshold_seconds=60):
        """Check if task is significantly overdue."""
        if not task["next_run"]:
            return False
        overdue_by = (
            datetime.now(timezone.utc) - task["next_run"]
        ).total_seconds()
        return overdue_by > threshold_seconds

    def test_recurring_task_creation(self):
        task = self._create_recurring_task("task-1", interval_seconds=3600)
        assert task["interval_seconds"] == 3600
        assert task["run_count"] == 0

    def test_mark_executed_updates_count(self):
        task = self._create_recurring_task("task-1", interval_seconds=60)
        self._mark_executed(task)
        assert task["run_count"] == 1
        assert task["last_run"] is not None


# --- Job status patterns ---


class TestJobStatus:
    """Tests for job status management patterns."""

    def _create_job(self, job_id):
        """Create a job."""
        return {
            "id": job_id,
            "status": "pending",
            "progress": 0,
            "result": None,
            "error": None,
            "started_at": None,
            "completed_at": None,
        }

    def _start_job(self, job):
        """Start a job."""
        job["status"] = "running"
        job["started_at"] = datetime.now(timezone.utc)
        return job

    def _complete_job(self, job, result):
        """Complete a job successfully."""
        job["status"] = "completed"
        job["result"] = result
        job["progress"] = 100
        job["completed_at"] = datetime.now(timezone.utc)
        return job

    def _fail_job(self, job, error):
        """Fail a job."""
        job["status"] = "failed"
        job["error"] = error
        job["completed_at"] = datetime.now(timezone.utc)
        return job

    def _update_progress(self, job, progress):
        """Update job progress."""
        job["progress"] = min(100, max(0, progress))
        return job

    def test_job_starts_pending(self):
        job = self._create_job("job-1")
        assert job["status"] == "pending"

    def test_start_job(self):
        job = self._create_job("job-1")
        self._start_job(job)
        assert job["status"] == "running"
        assert job["started_at"] is not None

    def test_complete_job(self):
        job = self._create_job("job-1")
        self._start_job(job)
        self._complete_job(job, {"data": "result"})
        assert job["status"] == "completed"
        assert job["result"] == {"data": "result"}

    def test_fail_job(self):
        job = self._create_job("job-1")
        self._start_job(job)
        self._fail_job(job, "Something went wrong")
        assert job["status"] == "failed"
        assert job["error"] == "Something went wrong"


# --- Promise/Future patterns ---


class TestPromisePatterns:
    """Tests for promise/future patterns."""

    def _create_promise(self):
        """Create a promise."""
        return {
            "state": "pending",
            "value": None,
            "error": None,
            "callbacks": [],
        }

    def _resolve(self, promise, value):
        """Resolve promise with value."""
        if promise["state"] != "pending":
            return False
        promise["state"] = "fulfilled"
        promise["value"] = value
        return True

    def _reject(self, promise, error):
        """Reject promise with error."""
        if promise["state"] != "pending":
            return False
        promise["state"] = "rejected"
        promise["error"] = error
        return True

    def _is_settled(self, promise):
        """Check if promise is settled."""
        return promise["state"] != "pending"

    def test_promise_starts_pending(self):
        promise = self._create_promise()
        assert promise["state"] == "pending"

    def test_resolve_promise(self):
        promise = self._create_promise()
        self._resolve(promise, "result")
        assert promise["state"] == "fulfilled"
        assert promise["value"] == "result"

    def test_reject_promise(self):
        promise = self._create_promise()
        self._reject(promise, "error")
        assert promise["state"] == "rejected"
        assert promise["error"] == "error"

    def test_cannot_resolve_twice(self):
        promise = self._create_promise()
        self._resolve(promise, "first")
        result = self._resolve(promise, "second")
        assert result is False
        assert promise["value"] == "first"


# --- Batch processing patterns ---


class TestBatchProcessing:
    """Tests for batch processing patterns."""

    def _create_batch(self, items, batch_size):
        """Split items into batches."""
        return [
            items[i : i + batch_size] for i in range(0, len(items), batch_size)
        ]

    def _process_batch(self, batch, processor):
        """Process a batch of items."""
        results = []
        errors = []
        for item in batch:
            try:
                result = processor(item)
                results.append({"item": item, "result": result})
            except Exception as e:
                errors.append({"item": item, "error": str(e)})
        return {"results": results, "errors": errors}

    def _get_batch_stats(self, batches_results):
        """Get statistics from batch processing."""
        total_success = sum(len(br["results"]) for br in batches_results)
        total_errors = sum(len(br["errors"]) for br in batches_results)
        return {"success": total_success, "errors": total_errors}

    def test_create_batches(self):
        items = list(range(10))
        batches = self._create_batch(items, 3)
        assert len(batches) == 4
        assert batches[0] == [0, 1, 2]

    def test_process_batch_success(self):
        batch = [1, 2, 3]
        result = self._process_batch(batch, lambda x: x * 2)
        assert len(result["results"]) == 3
        assert len(result["errors"]) == 0

    def test_process_batch_with_errors(self):
        batch = [1, 0, 2]

        def processor(x):
            return 10 / x

        result = self._process_batch(batch, processor)
        assert len(result["errors"]) == 1


# --- Retry patterns ---


class TestRetryPatterns:
    """Tests for retry patterns."""

    def _should_retry(self, attempt, max_attempts, error_type=None):
        """Determine if should retry."""
        if attempt >= max_attempts:
            return False
        retryable_errors = ["timeout", "connection", "temporary"]
        if error_type and error_type not in retryable_errors:
            return False
        return True

    def _calculate_delay(self, attempt, base_delay=1.0, strategy="exponential"):
        """Calculate retry delay."""
        if strategy == "constant":
            return base_delay
        if strategy == "linear":
            return base_delay * (attempt + 1)
        if strategy == "exponential":
            return base_delay * (2**attempt)
        return base_delay

    def _create_retry_context(self, max_attempts=3, base_delay=1.0):
        """Create retry context."""
        return {
            "max_attempts": max_attempts,
            "base_delay": base_delay,
            "current_attempt": 0,
            "errors": [],
        }

    def test_should_retry_within_limit(self):
        assert self._should_retry(0, 3) is True
        assert self._should_retry(2, 3) is True

    def test_should_not_retry_at_limit(self):
        assert self._should_retry(3, 3) is False

    def test_exponential_delay(self):
        assert self._calculate_delay(0, 1.0) == 1.0
        assert self._calculate_delay(1, 1.0) == 2.0
        assert self._calculate_delay(2, 1.0) == 4.0

    def test_linear_delay(self):
        assert self._calculate_delay(0, 1.0, "linear") == 1.0
        assert self._calculate_delay(1, 1.0, "linear") == 2.0


# --- Concurrency control patterns ---


class TestConcurrencyControl:
    """Tests for concurrency control patterns."""

    def _create_semaphore(self, max_concurrent):
        """Create a semaphore."""
        return {
            "max_concurrent": max_concurrent,
            "current": 0,
        }

    def _acquire(self, semaphore):
        """Acquire semaphore slot."""
        if semaphore["current"] >= semaphore["max_concurrent"]:
            return False
        semaphore["current"] += 1
        return True

    def _release(self, semaphore):
        """Release semaphore slot."""
        if semaphore["current"] > 0:
            semaphore["current"] -= 1
            return True
        return False

    def _get_available(self, semaphore):
        """Get available slots."""
        return semaphore["max_concurrent"] - semaphore["current"]

    def test_acquire_within_limit(self):
        sem = self._create_semaphore(3)
        assert self._acquire(sem) is True
        assert sem["current"] == 1

    def test_acquire_at_limit(self):
        sem = self._create_semaphore(1)
        self._acquire(sem)
        assert self._acquire(sem) is False

    def test_release_allows_acquire(self):
        sem = self._create_semaphore(1)
        self._acquire(sem)
        self._release(sem)
        assert self._acquire(sem) is True

    def test_available_slots(self):
        sem = self._create_semaphore(5)
        self._acquire(sem)
        self._acquire(sem)
        assert self._get_available(sem) == 3


# --- Timeout patterns ---


class TestTimeoutPatterns:
    """Tests for timeout handling patterns."""

    def _create_timeout_context(self, timeout_seconds):
        """Create timeout context."""
        return {
            "timeout_seconds": timeout_seconds,
            "started_at": datetime.now(timezone.utc),
            "timed_out": False,
        }

    def _is_timed_out(self, context):
        """Check if operation has timed out."""
        elapsed = (
            datetime.now(timezone.utc) - context["started_at"]
        ).total_seconds()
        return elapsed > context["timeout_seconds"]

    def _get_remaining_time(self, context):
        """Get remaining time before timeout."""
        elapsed = (
            datetime.now(timezone.utc) - context["started_at"]
        ).total_seconds()
        remaining = context["timeout_seconds"] - elapsed
        return max(0, remaining)

    def test_not_timed_out_immediately(self):
        context = self._create_timeout_context(60)
        assert self._is_timed_out(context) is False

    def test_remaining_time(self):
        context = self._create_timeout_context(60)
        remaining = self._get_remaining_time(context)
        assert 59 < remaining <= 60


# --- Work distribution patterns ---


class TestWorkDistribution:
    """Tests for work distribution patterns."""

    def _round_robin(self, workers, task_index):
        """Distribute task using round robin."""
        return workers[task_index % len(workers)]

    def _least_loaded(self, workers_with_load):
        """Select worker with least load."""
        return min(workers_with_load, key=lambda w: w["load"])

    def _weighted_random(self, workers_with_weights):
        """Select worker by weight (simplified - returns highest weight)."""
        return max(workers_with_weights, key=lambda w: w["weight"])

    def test_round_robin(self):
        workers = ["w1", "w2", "w3"]
        assert self._round_robin(workers, 0) == "w1"
        assert self._round_robin(workers, 1) == "w2"
        assert self._round_robin(workers, 3) == "w1"

    def test_least_loaded(self):
        workers = [
            {"id": "w1", "load": 10},
            {"id": "w2", "load": 5},
            {"id": "w3", "load": 8},
        ]
        selected = self._least_loaded(workers)
        assert selected["id"] == "w2"

    def test_weighted(self):
        workers = [
            {"id": "w1", "weight": 1},
            {"id": "w2", "weight": 3},
            {"id": "w3", "weight": 2},
        ]
        selected = self._weighted_random(workers)
        assert selected["id"] == "w2"
