import type { SQLiteDatabase } from 'expo-sqlite';
import { getSetting, upsertRemoteActivity } from './queries';

export type SyncResult = { synced: number; total: number; fetched?: number; error?: string };

export async function syncFeed(db: SQLiteDatabase): Promise<SyncResult> {
  const instanceUrl = (await getSetting(db, 'instance_url'))?.replace(/\/$/, '');
  const token = await getSetting(db, 'api_token');

  if (!instanceUrl || !token) {
    return { synced: 0, total: 0, error: 'No instance configured — add one in Settings.' };
  }

  let resp: Response;
  try {
    resp = await fetch(`${instanceUrl}/api/feed`, {
      headers: { Authorization: `Bearer ${token}` },
    });
  } catch {
    return { synced: 0, total: 0, error: 'Could not reach instance — check your connection.' };
  }

  if (resp.status === 401) {
    return { synced: 0, total: 0, error: 'Session expired — reconnect in Settings.' };
  }
  if (!resp.ok) {
    return { synced: 0, total: 0, error: `Server error (${resp.status})` };
  }

  const data: { activities?: RemoteSummary[] } = await resp.json();
  const activities = data.activities ?? [];

  const syncMode = (await getSetting(db, 'sync_mode')) ?? 'summaries';

  let synced = 0;
  for (const a of activities) {
    const detailJson = JSON.stringify({
      id: a.id,
      title: a.title ?? a.id,
      sport: a.sport ?? null,
      started_at: a.started_at ?? null,
      distance_m: a.distance_m ?? null,
      moving_time_s: a.moving_time_s ?? null,
      elevation_gain_m: a.elevation_gain_m ?? null,
      avg_speed_kmh: a.avg_speed_kmh ?? null,
      avg_hr_bpm: a.avg_hr_bpm ?? null,
      avg_power_w: a.avg_power_w ?? null,
    });
    const changed = await upsertRemoteActivity(db, a.id, detailJson);
    if (changed) synced++;
  }

  if (syncMode !== 'full') {
    return { synced, total: activities.length };
  }

  // Full mode: fetch geojson + timeseries for any activity missing them
  const headers = { Authorization: `Bearer ${token}` };
  let fetched = 0;
  for (const a of activities) {
    const row = db.getFirstSync<{ g: number; t: number }>(
      'SELECT (geojson IS NOT NULL) as g, (timeseries_json IS NOT NULL) as t FROM activities WHERE id = ?',
      [a.id],
    );
    if (row?.g && row?.t) continue;

    let gj: string | null = null;
    let ts: string | null = null;
    try {
      if (!row?.g) {
        const r = await fetch(`${instanceUrl}/api/activity/${a.id}/geojson`, { headers });
        if (r.ok) gj = await r.text();
      }
      if (!row?.t) {
        const r = await fetch(`${instanceUrl}/api/activity/${a.id}/timeseries`, { headers });
        if (r.ok) ts = await r.text();
      }
    } catch {}

    if (gj !== null || ts !== null) {
      await db.runAsync(
        `UPDATE activities SET
           geojson        = COALESCE(geojson,        ?),
           timeseries_json = COALESCE(timeseries_json, ?)
         WHERE id = ? AND origin = 'remote'`,
        [gj, ts, a.id],
      );
      fetched++;
    }
  }

  return { synced, total: activities.length, fetched };
}

type RemoteSummary = {
  id: string;
  title?: string;
  sport?: string;
  started_at?: string;
  distance_m?: number | null;
  moving_time_s?: number | null;
  elevation_gain_m?: number | null;
  avg_speed_kmh?: number | null;
  avg_hr_bpm?: number | null;
  avg_power_w?: number | null;
};