import fs from "fs";
import path from "path";

export type ReplicateMode = "cloud" | "local";

export type Settings = {
    replicateApiToken: string;
    jigsawApiKey: string;
    modelVersion: string;
    replicateEnabled: boolean;
    replicateMode: ReplicateMode;
    localEndpoint: string;
    adminPasswordHash: string;
};

const DEFAULT_SETTINGS: Settings = {
    replicateApiToken: process.env["REPLICATE_API_TOKEN"] ?? "",
    jigsawApiKey: process.env["JIGSAWSTACK_API_KEY"] ?? "",
    modelVersion: "jigsawstack/text-translate:454df4c49941c05dea05175bd37686d0872c73c1f9366d1c2505db32ade52a89",
    replicateEnabled: false,
    replicateMode: (process.env["REPLICATE_MODE"] as ReplicateMode) ?? "cloud",
    localEndpoint: process.env["LOCAL_MODEL_ENDPOINT"] ?? "http://localhost:5030/predictions",
    adminPasswordHash: process.env["ADMIN_PASSWORD"] ?? "admin"
};

/**
 * Resolve a writable path for settings.json.
 * Priority:
 *   1. SETTINGS_PATH env var (explicit override)
 *   2. <cwd>/data/settings.json  (default, works when data/ is writable)
 *   3. /tmp/lingvai-settings.json (fallback for read-only containers)
 */
function resolveSettingsPath(): string {
    if (process.env["SETTINGS_PATH"]) {
        return process.env["SETTINGS_PATH"];
    }
    const primary = path.join(process.cwd(), "data", "settings.json");
    try {
        const dir = path.dirname(primary);
        fs.mkdirSync(dir, { recursive: true });
        // Test write access by opening with 'a' (append/create without truncating)
        const fd = fs.openSync(primary, "a");
        fs.closeSync(fd);
        return primary;
    } catch {
        return path.join("/tmp", "lingvai-settings.json");
    }
}

// Resolve once at module load so every call uses the same path
const SETTINGS_PATH = resolveSettingsPath();

if (SETTINGS_PATH.startsWith("/tmp")) {
    console.warn(
        `[lingvai] data/settings.json is not writable. ` +
        `Settings will be stored at ${SETTINGS_PATH}. ` +
        `Mount a writable volume at /app/data or set SETTINGS_PATH to persist across restarts.`
    );
}

export function readSettings(): Settings {
    try {
        if (!fs.existsSync(SETTINGS_PATH)) {
            return { ...DEFAULT_SETTINGS };
        }
        const raw = fs.readFileSync(SETTINGS_PATH, "utf-8");
        return { ...DEFAULT_SETTINGS, ...JSON.parse(raw) };
    } catch {
        return { ...DEFAULT_SETTINGS };
    }
}

export function writeSettings(updates: Partial<Settings>): Settings {
    const current = readSettings();
    const next = { ...current, ...updates };
    const dir = path.dirname(SETTINGS_PATH);
    fs.mkdirSync(dir, { recursive: true });
    fs.writeFileSync(SETTINGS_PATH, JSON.stringify(next, null, 2), "utf-8");
    return next;
}