import { readdir, mkdir, stat } from 'node:fs/promises';
import { existsSync } from 'node:fs';
import { config, destOf } from '../config.js';
import { db } from '../db/index.js';
import { parseServerName } from './map-aliases.js';

/**
 * All server folders under SERVERS_ROOT. Used by seedServerRegistry to backfill
 * the servers table for any on-disk server directory that isn't yet tracked.
 */
export async function allServers(): Promise<string[]> {
    let entries;
    try {
        entries = await readdir(config.serversRoot, { withFileTypes: true });
    } catch {
        return [];
    }
    return entries
        .filter((e) => e.isDirectory())
        .map((e) => e.name)
        .sort();
}

/**
 * Match a server name against a list of glob-like patterns (supports `*` and
 * `?` and comma-separated lists).
 */
export function matchServers(all: string[], patterns: string[]): string[] {
    if (patterns.length === 0 || (patterns.length === 1 && patterns[0] === '*')) {
        return [...all];
    }
    const regexes = patterns
        .flatMap((p) => p.split(',').map((s) => s.trim()).filter(Boolean))
        .map((p) => new RegExp('^' + p.replace(/[.+^$()|{}\\]/g, '\\$&').replace(/\*/g, '.*').replace(/\?/g, '.') + '$'));
    return all.filter((name) => regexes.some((r) => r.test(name)));
}

/**
 * Ensure a server has an sp/ destination. Creates it when create=true.
 */
export async function ensureDest(
    server: string,
    create: boolean
): Promise<{ ok: true; path: string } | { ok: false; reason: string }> {
    const dest = destOf(server);
    if (existsSync(dest)) {
        try {
            const s = await stat(dest);
            if (!s.isDirectory()) return { ok: false, reason: 'dest is not a directory' };
        } catch (err) {
            return { ok: false, reason: `stat failed: ${(err as Error).message}` };
        }
        return { ok: true, path: dest };
    }
    if (!create) return { ok: false, reason: 'no sp folder — use create=true' };
    await mkdir(dest, { recursive: true });
    return { ok: true, path: dest };
}

// -- server registry --

export interface ServerRow {
    name: string;
    komodo_type: 'deployment' | 'stack' | 'container';
    komodo_name: string;
    komodo_server: string | null;
    game_port: number | null;
    rcon_host: string | null;
    game: string | null;
    map: string | null;
    last_players: number | null;
    last_checked_at: string | null;
    last_map: string | null;
    last_gametype: string | null;
    last_roster: string | null;
    last_seen_at: string | null;
    last_error: string | null;
    last_reply_snippet: string | null;
    created_at: string;
}

export async function seedServerRegistry(): Promise<number> {
    const rows = await allServers();
    const insert = db().prepare(
        'INSERT OR IGNORE INTO servers (name, komodo_type, komodo_name, game, map) VALUES (?, ?, ?, ?, ?)'
    );
    // Also backfill existing rows where game/map were never set (upgrade path
    // from before name-based auto-derivation existed).
    const backfill = db().prepare(
        'UPDATE servers SET game = COALESCE(game, ?), map = COALESCE(map, ?) WHERE name = ? AND (game IS NULL OR map IS NULL)'
    );
    let n = 0;
    const tx = db().transaction((names: string[]) => {
        for (const name of names) {
            const parsed = parseServerName(name);
            const game = parsed?.game ?? null;
            const map = parsed?.mapCanonical ?? null;
            const res = insert.run(name, 'deployment', name.replace(/_/g, '-'), game, map);
            if (res.changes > 0) {
                n++;
            } else {
                backfill.run(game, map, name);
            }
            if (parsed && !parsed.mapCanonical) {
                console.warn(`[servers] unknown map alias '${parsed.mapAlias}' for ${name} — add to T5_MAP_ALIASES`);
            }
        }
    });
    tx(rows);
    return n;
}

export function getServer(name: string): ServerRow | undefined {
    return db().prepare('SELECT * FROM servers WHERE name = ?').get(name) as ServerRow | undefined;
}

export function listServers(): ServerRow[] {
    return db().prepare('SELECT * FROM servers ORDER BY name').all() as ServerRow[];
}

export function setServerField(
    name: string,
    field: keyof ServerRow,
    value: string | number | null
): void {
    const allowed: Array<keyof ServerRow> = [
        'komodo_type',
        'komodo_name',
        'komodo_server',
        'game_port',
        'rcon_host',
        'game',
        'map',
        'last_players',
        'last_checked_at',
        'last_map',
        'last_gametype',
        'last_roster',
        'last_seen_at',
        'last_error',
        'last_reply_snippet'
    ];
    if (!allowed.includes(field)) throw new Error(`refusing to set ${field}`);
    db().prepare(`UPDATE servers SET ${field} = ? WHERE name = ?`).run(value, name);
}

/**
 * Which target rel_paths on this server are currently held by a running beta?
 * Returns Map<relPath, betaId>. A target held by beta X blocks other betas AND
 * blocks unrelated writes to that same target on that server.
 */
export function heldByBeta(server: string): Map<string, number> {
    const rows = db()
        .prepare(
            `SELECT s.target_rel_path AS target, b.id AS beta_id
             FROM beta_servers bs
             JOIN betas b ON b.id = bs.beta_id
             JOIN scripts s ON s.id = b.script_id
             WHERE bs.server = ? AND b.state = 'running'`
        )
        .all(server) as Array<{ target: string; beta_id: number }>;
    const map = new Map<string, number>();
    for (const r of rows) map.set(r.target, r.beta_id);
    return map;
}

/**
 * Which running beta (if any) owns a specific target rel_path on a server?
 */
export function ownerOf(server: string, target: string): number | null {
    const row = db()
        .prepare(
            `SELECT b.id AS beta_id
             FROM beta_servers bs
             JOIN betas b ON b.id = bs.beta_id
             JOIN scripts s ON s.id = b.script_id
             WHERE bs.server = ? AND s.target_rel_path = ? AND b.state = 'running'
             LIMIT 1`
        )
        .get(server, target) as { beta_id: number } | undefined;
    return row?.beta_id ?? null;
}