import { db } from '../db/index.js';
import type { GameTelemetry, ServerTiming } from '../../telemetry.js';
import { MIN_RECORDED_ROUND } from '../../match-history.js';
import { recordLeaderboardTelemetry } from './leaderboard-ingest.js';
import { latestGameSubmission } from './status-evidence.js';

export function listTelemetry(): GameTelemetry[] {
    const rows = db().prepare(`SELECT t.payload FROM server_telemetry t JOIN servers s ON s.name = t.server
        WHERE s.destroyed_at IS NULL AND t.payload IS NOT NULL`).all() as Array<{ payload: string }>;
    return rows.map(row => JSON.parse(row.payload) as GameTelemetry);
}

export function saveTelemetry(report: GameTelemetry): GameTelemetry {
    // Keep callers outside the HTTP route atomic too.
    const handle = db();
    return handle.transaction(() => {
        const row = handle.prepare('SELECT payload FROM server_telemetry WHERE server = ?').get(report.server) as { payload: string | null } | undefined;
        const previous: GameTelemetry | undefined = row?.payload ? JSON.parse(row.payload) : undefined;
        recordLeaderboardTelemetry(handle, report);
        // Record each occupancy transition at receipt, before a heartbeat can
        // replace game_start or an empty report between status polls.
        const after = latestGameSubmission(report.server);
        if (!after || Date.parse(report.receivedAt) > Date.parse(after)) {
            if (report.players.length > 0) {
                handle.prepare('UPDATE servers SET active_since = COALESCE(active_since, ?), inactive_since = NULL WHERE name = ?')
                    .run(report.receivedAt, report.server);
                if (report.event === 'game_start') {
                    handle.prepare('UPDATE servers SET game_started_at = ?, game_ended_at = NULL WHERE name = ?').run(report.receivedAt, report.server);
                } else if (report.event === 'game_end') {
                    handle.prepare('UPDATE servers SET game_ended_at = ? WHERE name = ?').run(report.receivedAt, report.server);
                }
            } else {
                handle.prepare(`UPDATE servers SET active_since = NULL, inactive_since = COALESCE(inactive_since, ?),
                    game_started_at = NULL, game_ended_at = NULL WHERE name = ?`).run(report.receivedAt, report.server);
            }
        }
        const serverTiming = handle.prepare(`SELECT active_since AS activeSince, inactive_since AS inactiveSince,
            game_started_at AS gameStartedAt, game_ended_at AS gameEndedAt FROM servers WHERE name = ?`).get(report.server) as ServerTiming;
        const match = handle.prepare('SELECT id FROM leaderboard_matches WHERE server = ? ORDER BY id DESC LIMIT 1').get(report.server) as { id: number };
        const sameMatch = previous?.timing?.matchId === match.id;
        // A gap beyond the normal heartbeat window cannot establish continuity.
        const continuous = previous && Date.parse(report.receivedAt) - Date.parse(previous.receivedAt) <= 120_000;
        report = { ...report, timing: { matchId: match.id, server: serverTiming, players: Object.fromEntries(report.players.map(player => {
            const prior = continuous ? previous?.timing?.players[player.guid] : undefined;
            return [player.guid, {
                serverJoinedAt: prior?.serverJoinedAt ?? report.receivedAt,
                matchJoinedAt: sameMatch && prior ? prior.matchJoinedAt : report.receivedAt,
                roundStarted: sameMatch && prior ? prior.roundStarted : report.event === 'game_start' ? 1 : report.round
            }];
        })) } };
        handle.prepare(`INSERT INTO server_telemetry (server, round, players, received_at, payload)
            VALUES (?, ?, ?, ?, ?) ON CONFLICT(server) DO UPDATE SET
            round = excluded.round, players = excluded.players, received_at = excluded.received_at, payload = excluded.payload`)
            .run(report.server, report.event === 'game_start' ? 0 : report.round, report.players.length, report.receivedAt, JSON.stringify(report));
        if (report.event === 'game_end') {
            // Legacy betas also take match completion directly from the script.
            if (report.round >= MIN_RECORDED_ROUND) handle.prepare(`UPDATE beta_servers SET match_seen_at = ? WHERE server = ? AND server_deleted_at IS NULL AND stage = 'awaiting-match'
                AND healthy_at <= ? AND beta_id IN (SELECT id FROM betas WHERE state = 'running')`)
                .run(report.receivedAt, report.server, report.receivedAt);
        }
        return report;
    })();
}