//! Thin async HTTP client for Apollo's `/api/places/*` and
//! `/api/location/*` endpoints.
//!
//! Apollo (the personal location-history viewer at the sibling repo) owns
//! user-defined Places: `name + lat/lon + radius_m + description (+ optional
//! category)`. We consume them in two places:
//!
//! 1. Automatic enrichment in [`crate::ai::insight_generator`] — the always-on
//!    path that folds the most-specific containing Place into the location
//!    string fed to the LLM.
//! 2. The agentic `get_personal_place_at` tool — lets the LLM ask "what
//!    user-defined place contains this lat/lon" during chat continuation.
//!
//! Apollo also owns the location track itself — cleaned of ghost devices
//! and coarse cell fixes, and current (HA siphon, Garmin), unlike the
//! frozen 2019 Takeout import in our `location_history` table. The
//! insight path's location context (`/api/location/at`) and the
//! `get_location_history` tool (`/api/location/day`) read it from Apollo
//! when configured (ImageApi #177, Apollo #51), falling back to the local
//! table when Apollo is unset or a call fails.
//!
//! Apollo does the haversine. This client is plumbing only — no geometry,
//! no caching at the moment. If insight throughput ever makes per-photo
//! HTTP latency a problem, swap to a small `Mutex<HashMap>` TTL cache here.
//!
//! Configured via `APOLLO_API_BASE_URL`. When unset, the client constructs
//! to a no-op shell: every method returns empty / `None`, the enrichment
//! path silently falls through to the legacy Nominatim-only output, and the
//! tool registration in `insight_generator` reports "integration disabled."

use anyhow::Result;
use reqwest::Client;
use serde::Deserialize;
use std::time::Duration;

// Public fields — `id`, `lat`, `lon` aren't read from the current tool
// output but are part of the wire model and useful for future tool
// extensions / debugging.
#[allow(dead_code)]
#[derive(Debug, Clone, Deserialize)]
pub struct ApolloPlace {
    pub id: i32,
    pub name: String,
    #[serde(default)]
    pub description: String,
    pub lat: f64,
    pub lon: f64,
    pub radius_m: i32,
    #[serde(default)]
    pub category: Option<String>,
}

#[derive(Deserialize)]
struct PlacesResponse {
    places: Vec<ApolloPlace>,
}

/// A kept location sample from Apollo, `offset_s` = sample ts − asked ts.
#[allow(dead_code)]
#[derive(Debug, Clone, Deserialize)]
pub struct LocationSample {
    pub ts: i64,
    pub lat: f64,
    pub lon: f64,
    #[serde(default)]
    pub accuracy: Option<i32>,
    #[serde(default)]
    pub activity: Option<String>,
    pub offset_s: i64,
}

#[allow(dead_code)]
#[derive(Debug, Clone, Deserialize)]
pub struct LocationPlace {
    pub id: i32,
    pub name: String,
    #[serde(default)]
    pub category: Option<String>,
    pub radius_m: i32,
}

/// The Place stay (run of samples inside one Place) covering an instant.
#[allow(dead_code)]
#[derive(Debug, Clone, Deserialize)]
pub struct LocationStay {
    pub place_id: i32,
    #[serde(default)]
    pub name: Option<String>,
    pub t0: i64,
    pub t1: i64,
}

/// `/api/location/at`: where the owner was at an instant. `sample` is
/// `None` when no kept sample lies within `max_gap` — Apollo says "no
/// data" rather than handing back a position from hours away.
#[allow(dead_code)]
#[derive(Debug, Clone, Deserialize)]
pub struct LocationAt {
    pub ts: i64,
    #[serde(default)]
    pub sample: Option<LocationSample>,
    #[serde(default)]
    pub nearest_offset_s: Option<i64>,
    #[serde(default)]
    pub bracketed: bool,
    #[serde(default)]
    pub place: Option<LocationPlace>,
    #[serde(default)]
    pub stay: Option<LocationStay>,
}

/// `/api/location/day`: the owner's timeline for one local day. `text` is
/// Apollo's compact rendering (one "HH:MM–HH:MM at Home" line per stay /
/// dwell / travel / gap), meant to go into a tool result as-is; the
/// structured `items` aren't needed here.
#[allow(dead_code)]
#[derive(Debug, Clone, Deserialize)]
pub struct LocationDay {
    pub tz: String,
    pub points: i64,
    pub km: f64,
    pub text: String,
}

#[derive(Clone)]
pub struct ApolloClient {
    client: Client,
    /// `None` means the integration is disabled — every method returns
    /// empty so the rest of insight generation runs unchanged.
    base_url: Option<String>,
}

impl ApolloClient {
    pub fn new(base_url: Option<String>) -> Self {
        // 5 s timeout: Apollo runs on the LAN. If it doesn't answer in
        // five seconds, treat the call as failed and fall back to the
        // legacy Nominatim path rather than block the whole insight.
        let client = Client::builder()
            .timeout(Duration::from_secs(5))
            .build()
            .expect("reqwest client build");
        Self { client, base_url }
    }

    /// Convenience for callers that need to know whether to register the
    /// `get_personal_place_at` tool (or to short-circuit enrichment).
    pub fn is_enabled(&self) -> bool {
        self.base_url.is_some()
    }

    /// Server-side haversine: returns places whose radius contains
    /// (lat, lon), already sorted smallest-radius-first by Apollo. The
    /// caller can take `[0]` for the most-specific match (matches
    /// Apollo's `primaryPlaceFor` rule on the frontend, so the carousel
    /// badge and the LLM prompt always agree).
    pub async fn places_containing(&self, lat: f64, lon: f64) -> Vec<ApolloPlace> {
        let Some(base) = self.base_url.as_deref() else {
            return Vec::new();
        };
        match self.fetch_places_containing(base, lat, lon).await {
            Ok(places) => places,
            Err(err) => {
                log::warn!("apollo_client: places_containing({lat:.4}, {lon:.4}) failed: {err}");
                Vec::new()
            }
        }
    }

    /// Where the owner was at `ts` (real UTC seconds). `None` when the
    /// integration is disabled or the call fails — callers fall back to
    /// the local table; `Some` with `sample: None` means Apollo answered
    /// "no data within `max_gap`", which callers should respect.
    pub async fn location_at(&self, ts: i64, max_gap: i64) -> Option<LocationAt> {
        let base = self.base_url.as_deref()?;
        let url = format!("{}/api/location/at", base.trim_end_matches('/'));
        let result: Result<LocationAt> = async {
            Ok(self
                .client
                .get(&url)
                .query(&[("ts", ts), ("max_gap", max_gap)])
                .send()
                .await?
                .error_for_status()?
                .json()
                .await?)
        }
        .await;
        result
            .map_err(|err| log::warn!("apollo_client: location_at({ts}) failed: {err}"))
            .ok()
    }

    /// The owner's timeline for `date` (YYYY-MM-DD) as a local day in
    /// `tz` (IANA). `None` when disabled or the call fails.
    pub async fn location_day(&self, date: &str, tz: &str) -> Option<LocationDay> {
        let base = self.base_url.as_deref()?;
        let url = format!("{}/api/location/day", base.trim_end_matches('/'));
        let result: Result<LocationDay> = async {
            Ok(self
                .client
                .get(&url)
                .query(&[("date", date), ("tz", tz)])
                .send()
                .await?
                .error_for_status()?
                .json()
                .await?)
        }
        .await;
        result
            .map_err(|err| log::warn!("apollo_client: location_day({date}, {tz}) failed: {err}"))
            .ok()
    }

    async fn fetch_places_containing(
        &self,
        base: &str,
        lat: f64,
        lon: f64,
    ) -> Result<Vec<ApolloPlace>> {
        let url = format!("{}/api/places/contains", base.trim_end_matches('/'));
        let resp = self
            .client
            .get(&url)
            .query(&[("lat", lat), ("lon", lon)])
            .send()
            .await?
            .error_for_status()?;
        let body: PlacesResponse = resp.json().await?;
        Ok(body.places)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn location_at_parses_hit_and_miss() {
        let hit: LocationAt = serde_json::from_str(
            r#"{"ts": 100, "max_gap": 1800,
                "sample": {"ts": 120, "lat": 41.46, "lon": -81.93, "accuracy": 19, "activity": "STILL", "offset_s": 20},
                "nearest_offset_s": 20, "bracketed": true,
                "place": {"id": 7, "name": "Work", "category": null, "radius_m": 250},
                "stay": {"place_id": 7, "name": "Work", "t0": 50, "t1": 900}}"#,
        )
        .unwrap();
        assert_eq!(hit.sample.unwrap().offset_s, 20);
        assert_eq!(hit.place.unwrap().name, "Work");
        assert_eq!(hit.stay.unwrap().t1, 900);

        let miss: LocationAt = serde_json::from_str(
            r#"{"ts": 100, "max_gap": 1800, "sample": null, "nearest_offset_s": -7200,
                "bracketed": false, "place": null, "stay": null}"#,
        )
        .unwrap();
        assert!(miss.sample.is_none());
        assert_eq!(miss.nearest_offset_s, Some(-7200));
    }

    #[test]
    fn location_day_ignores_items() {
        let day: LocationDay = serde_json::from_str(
            r#"{"start": 0, "end": 86400, "tz": "America/New_York",
                "items": [{"kind": "gap", "t0": 0, "t1": 1}], "points": 3, "km": 1.5,
                "text": "00:00–23:59 at Home"}"#,
        )
        .unwrap();
        assert_eq!(day.text, "00:00–23:59 at Home");
        assert_eq!(day.points, 3);
    }

    #[tokio::test]
    async fn disabled_client_returns_none() {
        let c = ApolloClient::new(None);
        assert!(c.location_at(0, 1800).await.is_none());
        assert!(c.location_day("2016-01-01", "UTC").await.is_none());
    }
}