"""Unit tests for reconciler timeout and failure safeguards."""

from __future__ import annotations

from dataclasses import dataclass

from nix_builder_autoscaler.config import AppConfig, AwsConfig, CapacityConfig
from nix_builder_autoscaler.metrics import MetricsRegistry
from nix_builder_autoscaler.models import SlotState
from nix_builder_autoscaler.providers.clock import FakeClock
from nix_builder_autoscaler.providers.haproxy import SlotHealth
from nix_builder_autoscaler.reconciler import Reconciler
from nix_builder_autoscaler.state_db import StateDB


@dataclass
class _Instance:
    state: str
    slot_id: str
    tailscale_ip: str | None = None


class _RuntimeStub:
    def __init__(self) -> None:
        self.instances: dict[str, _Instance] = {}
        self.terminate_calls: list[str] = []

    def list_managed_instances(self) -> list[dict]:
        return [
            {
                "instance_id": iid,
                "state": inst.state,
                "slot_id": inst.slot_id,
            }
            for iid, inst in self.instances.items()
            if inst.state != "terminated"
        ]

    def describe_instance(self, instance_id: str) -> dict:
        inst = self.instances.get(instance_id)
        if inst is None:
            return {"state": "terminated", "tailscale_ip": None, "launch_time": None}
        return {"state": inst.state, "tailscale_ip": inst.tailscale_ip, "launch_time": None}

    def terminate_instance(self, instance_id: str) -> None:
        self.terminate_calls.append(instance_id)
        if instance_id in self.instances:
            self.instances[instance_id].state = "terminated"


class _HAProxyStub:
    def __init__(self, health: dict[str, SlotHealth] | None = None) -> None:
        self.health = health or {}

    def set_slot_addr(self, slot_id: str, ip: str, port: int = 22) -> None:  # noqa: ARG002
        return

    def enable_slot(self, slot_id: str) -> None:  # noqa: ARG002
        return

    def disable_slot(self, slot_id: str) -> None:  # noqa: ARG002
        return

    def read_slot_health(self) -> dict[str, SlotHealth]:
        return self.health


def _make_env(
    *,
    launch_timeout=300,
    boot_timeout=300,
    binding_timeout=180,
    terminating_timeout=300,
    termination_cooldown=0,
):
    clock = FakeClock()
    db = StateDB(":memory:", clock=clock)
    db.init_schema()
    db.init_slots("slot", 1, "x86_64-linux", "all")

    runtime = _RuntimeStub()
    haproxy = _HAProxyStub()
    config = AppConfig(
        capacity=CapacityConfig(
            launch_timeout_seconds=launch_timeout,
            boot_timeout_seconds=boot_timeout,
            binding_timeout_seconds=binding_timeout,
            terminating_timeout_seconds=terminating_timeout,
            termination_cooldown_seconds=termination_cooldown,
        ),
        aws=AwsConfig(region="us-east-1"),
    )
    metrics = MetricsRegistry()
    reconciler = Reconciler(db, runtime, haproxy, config, clock, metrics)
    return db, runtime, reconciler, clock


def test_launching_timeout_moves_slot_to_terminating() -> None:
    db, runtime, reconciler, clock = _make_env(launch_timeout=10)
    runtime.instances["i-1"] = _Instance(state="pending", slot_id="slot001")
    db.update_slot_state("slot001", SlotState.LAUNCHING, instance_id="i-1")

    clock.advance(11)
    reconciler.tick()

    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.TERMINATING.value
    assert runtime.terminate_calls == ["i-1"]


def test_launching_stopped_state_begins_termination() -> None:
    db, runtime, reconciler, _ = _make_env()
    runtime.instances["i-1"] = _Instance(state="stopped", slot_id="slot001")
    db.update_slot_state("slot001", SlotState.LAUNCHING, instance_id="i-1")

    reconciler.tick()

    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.TERMINATING.value
    assert runtime.terminate_calls == ["i-1"]


def test_booting_timeout_moves_slot_to_terminating() -> None:
    db, runtime, reconciler, clock = _make_env(boot_timeout=15)
    runtime.instances["i-2"] = _Instance(state="running", slot_id="slot001", tailscale_ip=None)
    db.update_slot_state("slot001", SlotState.BOOTING, instance_id="i-2")

    clock.advance(16)
    reconciler.tick()

    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.TERMINATING.value
    assert runtime.terminate_calls == ["i-2"]


def test_binding_timeout_moves_slot_to_terminating() -> None:
    db, runtime, reconciler, clock = _make_env(binding_timeout=8)
    runtime.instances["i-3"] = _Instance(
        state="running",
        slot_id="slot001",
        tailscale_ip="100.64.0.3",
    )
    db.update_slot_state(
        "slot001",
        SlotState.BINDING,
        instance_id="i-3",
        instance_ip="100.64.0.3",
    )

    clock.advance(9)
    reconciler.tick()

    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.TERMINATING.value
    assert runtime.terminate_calls == ["i-3"]


def test_binding_stopped_state_begins_termination() -> None:
    db, runtime, reconciler, _ = _make_env()
    runtime.instances["i-4"] = _Instance(
        state="stopping",
        slot_id="slot001",
        tailscale_ip="100.64.0.4",
    )
    db.update_slot_state(
        "slot001",
        SlotState.BINDING,
        instance_id="i-4",
        instance_ip="100.64.0.4",
    )

    reconciler.tick()

    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.TERMINATING.value
    assert runtime.terminate_calls == ["i-4"]


def test_terminating_timeout_reissues_terminate_with_pacing() -> None:
    db, runtime, reconciler, clock = _make_env(terminating_timeout=5)
    runtime.instances["i-5"] = _Instance(state="shutting-down", slot_id="slot001")
    db.update_slot_state("slot001", SlotState.TERMINATING, instance_id="i-5")

    clock.advance(6)
    reconciler.tick()

    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.TERMINATING.value
    assert runtime.terminate_calls == ["i-5"]

    # Immediate next tick should not retry yet because last_state_change was refreshed.
    reconciler.tick()
    assert runtime.terminate_calls == ["i-5"]


def test_termination_cooldown_spaces_terminations() -> None:
    db, runtime, reconciler, clock = _make_env(termination_cooldown=30)
    runtime.instances["i-6"] = _Instance(state="running", slot_id="slot001")
    db.update_slot_state("slot001", SlotState.DRAINING, instance_id="i-6", lease_count=0)

    reconciler.tick()
    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.TERMINATING.value
    assert runtime.terminate_calls == ["i-6"]

    # New draining cycle before cooldown expires should not terminate yet.
    runtime.instances["i-7"] = _Instance(state="running", slot_id="slot001")
    db.update_slot_state("slot001", SlotState.DRAINING, instance_id="i-7", lease_count=0)
    clock.advance(10)
    reconciler.tick()

    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.DRAINING.value
    assert runtime.terminate_calls == ["i-6"]

    # After cooldown, termination proceeds.
    clock.advance(21)
    reconciler.tick()
    slot = db.get_slot("slot001")
    assert slot is not None
    assert slot["state"] == SlotState.TERMINATING.value
    assert runtime.terminate_calls == ["i-6", "i-7"]