from __future__ import annotations

import json

import pytest
from fastapi import Response

from app.api.v1 import visualization
from app.services.earth_layer_cache import (
    EarthLayerCachePolicy,
    apply_payload_budget,
    earth_layer_cache,
    format_bbox_key,
    quantize_bbox,
    resolve_layer_payload,
)


class FakeRedis:
    def __init__(self, *, fail: bool = False) -> None:
        self.store: dict[str, str] = {}
        self.fail = fail
        self.lock_claimed = False

    def _maybe_fail(self) -> None:
        if self.fail:
            raise RuntimeError("redis unavailable")

    def get(self, key: str):
        self._maybe_fail()
        return self.store.get(key)

    def set(self, key: str, value: str, nx: bool = False, ex: int | None = None):
        self._maybe_fail()
        if nx and key in self.store:
            return False
        self.store[key] = value
        return True

    def setex(self, key: str, _seconds: int, value: str):
        self._maybe_fail()
        self.store[key] = value
        return True

    def delete(self, *keys: str):
        self._maybe_fail()
        deleted = 0
        for key in keys:
            deleted += 1 if self.store.pop(key, None) is not None else 0
        return deleted

    def scan_iter(self, match: str):
        self._maybe_fail()
        prefix = match.rstrip("*")
        for key in list(self.store):
            if key.startswith(prefix):
                yield key

    def memory_usage(self, key: str):
        value = self.store.get(key, "")
        return len(value.encode("utf-8"))


@pytest.fixture(autouse=True)
def fake_cache_client():
    previous = earth_layer_cache._client
    fake = FakeRedis()
    earth_layer_cache._client = fake
    try:
        yield fake
    finally:
        earth_layer_cache._client = previous


def test_quantized_bbox_key_is_stable_for_small_movements():
    first = format_bbox_key(quantize_bbox((10.01, 59.04, 10.96, 60.02)))
    second = format_bbox_key(quantize_bbox((10.04, 59.01, 10.99, 60.04)))

    assert first == second
    assert first == "10.0,59.0,11.0,60.0"


def test_payload_budget_truncates_features():
    payload = {
        "type": "FeatureCollection",
        "features": [{"id": index} for index in range(5)],
    }
    policy = EarthLayerCachePolicy(60, 120, max_features=2, max_bytes=1024)

    result = apply_payload_budget(payload, policy)

    assert len(result["features"]) == 2
    assert result["diagnostics"]["truncated"] is True
    assert result["diagnostics"]["limit_reason"] == "feature_budget"
    assert result["diagnostics"]["original_feature_count"] == 5


@pytest.mark.asyncio
async def test_resolve_layer_payload_writes_fresh_and_stale(fake_cache_client):
    calls = 0

    async def builder():
        nonlocal calls
        calls += 1
        return {"type": "FeatureCollection", "features": [{"id": "a"}]}

    key = earth_layer_cache.key("satellites", limit="all")
    policy = EarthLayerCachePolicy(60, 120)

    first = await resolve_layer_payload(key=key, policy=policy, builder=builder)
    second = await resolve_layer_payload(key=key, policy=policy, builder=builder)

    assert first.state == "refresh"
    assert second.state == "hit"
    assert calls == 1
    assert key in fake_cache_client.store
    assert f"{key}:stale" in fake_cache_client.store


@pytest.mark.asyncio
async def test_resolve_layer_payload_returns_stale_when_builder_fails(fake_cache_client):
    key = earth_layer_cache.key("bgp-incidents", status="active")
    fake_cache_client.store[f"{key}:stale"] = json.dumps({"type": "FeatureCollection", "features": []})

    async def builder():
        raise RuntimeError("db exploded")

    result = await resolve_layer_payload(
        key=key,
        policy=EarthLayerCachePolicy(60, 120),
        builder=builder,
    )

    assert result.state == "stale"
    assert result.payload["features"] == []


@pytest.mark.asyncio
async def test_resolve_layer_payload_uses_stale_during_lock_contention(fake_cache_client):
    key = earth_layer_cache.key("cables")
    fake_cache_client.store[earth_layer_cache.lock_key(key)] = "1"
    fake_cache_client.store[f"{key}:stale"] = json.dumps(
        {"type": "FeatureCollection", "features": [{"id": "stale-cable"}]}
    )
    calls = 0

    async def builder():
        nonlocal calls
        calls += 1
        return {"type": "FeatureCollection", "features": [{"id": "fresh-cable"}]}

    result = await resolve_layer_payload(
        key=key,
        policy=EarthLayerCachePolicy(60, 120),
        builder=builder,
    )

    assert result.state == "stale"
    assert result.payload["features"][0]["id"] == "stale-cable"
    assert calls == 0


@pytest.mark.asyncio
async def test_resolve_layer_payload_bypasses_redis_failure():
    previous = earth_layer_cache._client
    earth_layer_cache._client = FakeRedis(fail=True)
    try:
        async def builder():
            return {"type": "FeatureCollection", "features": [{"id": "safe"}]}

        result = await resolve_layer_payload(
            key=earth_layer_cache.key("cables"),
            policy=EarthLayerCachePolicy(60, 120),
            builder=builder,
        )

        assert result.state == "bypass"
        assert result.payload["features"][0]["id"] == "safe"
    finally:
        earth_layer_cache._client = previous


@pytest.mark.asyncio
async def test_visualization_endpoint_sets_cache_headers(fake_cache_client, monkeypatch):
    calls = 0

    async def fake_build_satellites_geojson(*, limit, db):
        nonlocal calls
        calls += 1
        return {"type": "FeatureCollection", "features": [{"id": f"sat-{limit}"}], "count": 1}

    monkeypatch.setattr(visualization, "_build_satellites_geojson", fake_build_satellites_geojson)

    first_response = Response()
    first = await visualization.get_satellites_geojson(limit=25, db=object(), response=first_response)
    second_response = Response()
    second = await visualization.get_satellites_geojson(limit=25, db=object(), response=second_response)

    assert first == second
    assert calls == 1
    assert first_response.headers["X-Planet-Cache"] == "refresh"
    assert second_response.headers["X-Planet-Cache"] == "hit"


@pytest.mark.asyncio
async def test_vessel_snapshot_uses_short_cache(fake_cache_client, monkeypatch):
    calls = 0

    async def fake_load_raw_vessel_snapshot_features(db, *, bbox, limit, observed_since):
        nonlocal calls
        calls += 1
        return (
            [
                {
                    "type": "Feature",
                    "geometry": {"type": "Point", "coordinates": [10.1, 59.1]},
                    "properties": {"mmsi": 123, "vessel_type_name": "Cargo"},
                }
            ],
            {"raw_feature_count": 1},
        )

    monkeypatch.setattr(
        visualization,
        "_load_raw_vessel_snapshot_features",
        fake_load_raw_vessel_snapshot_features,
    )

    first_response = Response()
    first = await visualization.build_vessel_snapshot_response(
        object(),
        bbox=(10.01, 59.04, 10.96, 60.02),
        zoom=12,
        type_filter=None,
        limit=1000,
        since_minutes=60,
        response=first_response,
    )
    second_response = Response()
    second = await visualization.build_vessel_snapshot_response(
        object(),
        bbox=(10.04, 59.01, 10.99, 60.04),
        zoom=12,
        type_filter=None,
        limit=1000,
        since_minutes=60,
        response=second_response,
    )

    assert first["count"] == 1
    assert second == first
    assert calls == 1
    assert first_response.headers["X-Planet-Cache"] == "refresh"
    assert second_response.headers["X-Planet-Cache"] == "hit"