"""System metrics collection using psutil."""

import socket
import time
from dataclasses import dataclass, field

import psutil


@dataclass
class MetricPoint:
    """A single metric data point."""

    metric_type: str
    value: float
    labels: dict[str, str] = field(default_factory=dict)


@dataclass
class MetricsBatch:
    """A batch of metrics from a single collection cycle."""

    machine_id: str
    hostname: str
    timestamp_ms: int
    metrics: list[MetricPoint]


class MetricsCollector:
    """Collects system metrics using psutil."""

    def __init__(
        self,
        machine_id: str,
        collect_cpu: bool = True,
        collect_memory: bool = True,
        collect_disk: bool = True,
        collect_network: bool = True,
        collect_load: bool = True,
    ):
        self.machine_id = machine_id
        self.hostname = socket.gethostname()

        self.collect_cpu = collect_cpu
        self.collect_memory = collect_memory
        self.collect_disk = collect_disk
        self.collect_network = collect_network
        self.collect_load = collect_load

        # Track previous network counters for rate calculation
        self._prev_net_io: psutil._common.snetio | None = None
        self._prev_net_time: float | None = None

    def collect(self) -> MetricsBatch:
        """Collect all enabled metrics and return as a batch."""
        metrics: list[MetricPoint] = []

        if self.collect_cpu:
            metrics.extend(self._collect_cpu())

        if self.collect_memory:
            metrics.extend(self._collect_memory())

        if self.collect_disk:
            metrics.extend(self._collect_disk())

        if self.collect_network:
            metrics.extend(self._collect_network())

        if self.collect_load:
            metrics.extend(self._collect_load())

        return MetricsBatch(
            machine_id=self.machine_id,
            hostname=self.hostname,
            timestamp_ms=int(time.time() * 1000),
            metrics=metrics,
        )

    def _collect_cpu(self) -> list[MetricPoint]:
        """Collect CPU metrics."""
        metrics = []

        # Overall CPU percent
        cpu_percent = psutil.cpu_percent(interval=None)
        metrics.append(
            MetricPoint(
                metric_type="CPU_PERCENT",
                value=cpu_percent,
            )
        )

        # Per-core CPU percent
        per_cpu = psutil.cpu_percent(interval=None, percpu=True)
        for i, pct in enumerate(per_cpu):
            metrics.append(
                MetricPoint(
                    metric_type="CPU_PERCENT_PER_CORE",
                    value=pct,
                    labels={"core": str(i)},
                )
            )

        return metrics

    def _collect_memory(self) -> list[MetricPoint]:
        """Collect memory metrics."""
        mem = psutil.virtual_memory()

        return [
            MetricPoint(metric_type="MEMORY_PERCENT", value=mem.percent),
            MetricPoint(metric_type="MEMORY_USED_BYTES", value=float(mem.used)),
            MetricPoint(
                metric_type="MEMORY_AVAILABLE_BYTES", value=float(mem.available)
            ),
        ]

    def _collect_disk(self) -> list[MetricPoint]:
        """Collect disk metrics."""
        metrics = []

        # Disk usage for root partition
        try:
            disk = psutil.disk_usage("/")
            metrics.append(
                MetricPoint(
                    metric_type="DISK_PERCENT",
                    value=disk.percent,
                    labels={"mount": "/"},
                )
            )
            metrics.append(
                MetricPoint(
                    metric_type="DISK_USED_BYTES",
                    value=float(disk.used),
                    labels={"mount": "/"},
                )
            )
        except (PermissionError, FileNotFoundError):
            pass

        # Disk I/O rates
        try:
            io = psutil.disk_io_counters()
            if io:
                metrics.append(
                    MetricPoint(
                        metric_type="DISK_READ_BYTES_SEC",
                        value=float(
                            io.read_bytes
                        ),  # Will be converted to rate by aggregator
                    )
                )
                metrics.append(
                    MetricPoint(
                        metric_type="DISK_WRITE_BYTES_SEC",
                        value=float(io.write_bytes),
                    )
                )
        except (PermissionError, AttributeError):
            pass

        return metrics

    def _collect_network(self) -> list[MetricPoint]:
        """Collect network metrics with rate calculation."""
        metrics = []

        try:
            net_io = psutil.net_io_counters()
            current_time = time.time()

            if self._prev_net_io is not None and self._prev_net_time is not None:
                time_delta = current_time - self._prev_net_time
                if time_delta > 0:
                    bytes_sent_rate = (
                        net_io.bytes_sent - self._prev_net_io.bytes_sent
                    ) / time_delta
                    bytes_recv_rate = (
                        net_io.bytes_recv - self._prev_net_io.bytes_recv
                    ) / time_delta

                    metrics.append(
                        MetricPoint(
                            metric_type="NETWORK_SENT_BYTES_SEC",
                            value=bytes_sent_rate,
                        )
                    )
                    metrics.append(
                        MetricPoint(
                            metric_type="NETWORK_RECV_BYTES_SEC",
                            value=bytes_recv_rate,
                        )
                    )

            self._prev_net_io = net_io
            self._prev_net_time = current_time

            # Connection count
            connections = len(psutil.net_connections(kind="inet"))
            metrics.append(
                MetricPoint(
                    metric_type="NETWORK_CONNECTIONS",
                    value=float(connections),
                )
            )
        except (PermissionError, psutil.AccessDenied):
            pass

        return metrics

    def _collect_load(self) -> list[MetricPoint]:
        """Collect load average metrics (Unix only)."""
        metrics = []

        try:
            load1, load5, load15 = psutil.getloadavg()
            metrics.append(MetricPoint(metric_type="LOAD_AVG_1M", value=load1))
            metrics.append(MetricPoint(metric_type="LOAD_AVG_5M", value=load5))
            metrics.append(MetricPoint(metric_type="LOAD_AVG_15M", value=load15))
        except (AttributeError, OSError):
            # Windows doesn't have getloadavg
            pass

        # Process count
        metrics.append(
            MetricPoint(
                metric_type="PROCESS_COUNT",
                value=float(len(psutil.pids())),
            )
        )

        return metrics