import fs from 'fs';
import path from 'path';
import { isObject } from './coerce';
import { normalizeUpdateSourceConfig, type UpdateSourceConfig } from './update-source';

export interface RuntimeConfig {
    updateSource?: UpdateSourceConfig;
    webuiPort?: number;
    /** When true, every newly-discovered QQ process gets auto-injected by
     * the HookManager. Also overridable at runtime via SNOWLUMA_HOOK_AUTOLOAD.
     * Defaults to false; the Docker image flips it on in supervisord.conf. */
    hookAutoLoad?: boolean;
    /** WebUI listener bind address. '127.0.0.1' = localhost-only (default),
     * '0.0.0.0' = all IPv4 interfaces. Listener-level: change needs a restart. */
    webuiHost?: string;
    /** WebUI TLS. Cert/key live in config/cert.pem + config/key.pem; this
     * only flips serving on/off. Listener-level: change needs a restart. */
    webuiTls?: { enabled?: boolean };
    /** Raw trust-proxy directive (same domain as SNOWLUMA_WEBUI_TRUST_PROXY),
     * consumed by the WebUI's client-ip resolver. '' = trust nobody. */
    trustProxy?: string;
    /** Aggregate cap for every managed file below the log root. */
    logMaxTotalMb?: number;
    /** Calendar-day retention. Zero disables date-based deletion. */
    logRetainDays?: number;
    /** Duplicate UIN-scoped lines into logs/<uin>/ in addition to the shared log. */
    logPerUin?: boolean;
}

const CONFIG_DIR = 'config';
const RUNTIME_CONFIG_PATH = path.join(CONFIG_DIR, 'runtime.json');

const DEFAULT_WEBUI_PORT = 5099;
const DEFAULT_WEBUI_HOST = '127.0.0.1';
export const DEFAULT_LOG_MAX_TOTAL_MB = 1024;
export const DEFAULT_LOG_RETAIN_DAYS = 7;
export const DEFAULT_LOG_PER_UIN = false;
export const MAX_LOG_TOTAL_MB = Math.floor(Number.MAX_SAFE_INTEGER / (1024 * 1024));
export const MAX_LOG_RETAIN_DAYS = Math.floor(Number.MAX_SAFE_INTEGER / (24 * 60 * 60 * 1000));

/**
 * Pure on-disk-object → typed config normalization (defaults + validation,
 * no fs / no env). Exported for testing; `loadRuntimeConfig` wraps it.
 */
export function normalizeRuntimeConfig(parsed: unknown): RuntimeConfig {
    const obj = isObject(parsed) ? parsed : {};
    return {
        ...(obj.updateSource === undefined
            ? {}
            : { updateSource: normalizeUpdateSourceConfig(obj.updateSource) }),
        webuiPort: normalizePort(obj.webuiPort ?? DEFAULT_WEBUI_PORT, DEFAULT_WEBUI_PORT),
        hookAutoLoad: normalizeBool(obj.hookAutoLoad, false),
        webuiHost: normalizeHost(obj.webuiHost),
        webuiTls: {
            enabled: isObject(obj.webuiTls) ? normalizeBool(obj.webuiTls.enabled, false) : false,
        },
        trustProxy: typeof obj.trustProxy === 'string' ? obj.trustProxy : '',
        logMaxTotalMb: normalizeRequiredInteger(
            obj.logMaxTotalMb,
            DEFAULT_LOG_MAX_TOTAL_MB,
            1,
            MAX_LOG_TOTAL_MB,
            'logMaxTotalMb',
        ),
        logRetainDays: normalizeRequiredInteger(
            obj.logRetainDays,
            DEFAULT_LOG_RETAIN_DAYS,
            0,
            MAX_LOG_RETAIN_DAYS,
            'logRetainDays',
        ),
        logPerUin: normalizeRequiredBool(obj.logPerUin, DEFAULT_LOG_PER_UIN, 'logPerUin'),
    };
}

/**
 * Pure SNOWLUMA_* env → override patch (no fs). Env wins over runtime.json
 * (a trusted launcher like SnowLumaDesktop pins these per-launch without
 * rewriting the file). Absent vars produce no key.
 */
export function resolveRuntimeEnvOverrides(env: NodeJS.ProcessEnv): Partial<RuntimeConfig> {
    const out: Partial<RuntimeConfig> = {};

    const port = parsePortString(env.SNOWLUMA_WEBUI_PORT);

    if (port !== undefined) {
        out.webuiPort = port;
    }

    const host = env.SNOWLUMA_WEBUI_HOST;

    if (typeof host === 'string' && host.trim()) {
        out.webuiHost = host.trim();
    }

    // Present-but-"0"/"off" is a deliberate override (trust nobody), distinct
    // from "absent" — so gate on key presence, not truthiness.
    const tp = env.SNOWLUMA_WEBUI_TRUST_PROXY;

    if (typeof tp === 'string') {
        out.trustProxy = tp;
    }

    const logMaxTotalMb = parseRequiredIntegerEnv(
        env.SNOWLUMA_LOG_MAX_TOTAL_MB,
        1,
        MAX_LOG_TOTAL_MB,
        'SNOWLUMA_LOG_MAX_TOTAL_MB',
    );

    if (logMaxTotalMb !== undefined) {
        out.logMaxTotalMb = logMaxTotalMb;
    }

    const logRetainDays = parseRequiredIntegerEnv(
        env.SNOWLUMA_LOG_RETAIN_DAYS,
        0,
        MAX_LOG_RETAIN_DAYS,
        'SNOWLUMA_LOG_RETAIN_DAYS',
    );

    if (logRetainDays !== undefined) {
        out.logRetainDays = logRetainDays;
    }

    const logPerUin = parseRequiredBoolEnv(env.SNOWLUMA_LOG_PER_UIN, 'SNOWLUMA_LOG_PER_UIN');

    if (logPerUin !== undefined) {
        out.logPerUin = logPerUin;
    }

    const webuiTls = parseRequiredBoolEnv(env.SNOWLUMA_WEBUI_TLS, 'SNOWLUMA_WEBUI_TLS');

    if (webuiTls !== undefined) {
        out.webuiTls = { enabled: webuiTls };
    }

    return out;
}

export function loadRuntimeConfig(): RuntimeConfig {
    fs.mkdirSync(CONFIG_DIR, { recursive: true });

    const parsed = tryLoadRuntimeConfig();
    const normalized = normalizeRuntimeConfig(parsed ?? {});

    // Persist when the file is absent or when normalization changed/backfilled
    // anything (e.g. an older runtime.json lacking webuiHost/webuiTls).
    if (parsed === null || !sameRuntimeConfig(parsed, normalized)) {
        saveRuntimeConfig(normalized);
    }

    // Env overrides apply in-memory only — never written back to disk.
    return { ...normalized, ...resolveRuntimeEnvOverrides(process.env) };
}

/**
 * Read the persisted config (normalized, no env overrides, no write). For the
 * settings panel's GET — shows what's actually saved/editable on disk.
 */
export function readRuntimeConfig(): RuntimeConfig {
    return normalizeRuntimeConfig(tryLoadRuntimeConfig() ?? {});
}

/**
 * Persist a partial update. Merges onto the ON-DISK config (not the env-merged
 * runtime view) so an env override (e.g. SNOWLUMA_WEBUI_PORT) is never baked
 * into runtime.json. Returns the new persisted config (without env overrides).
 */
export function updateRuntimeConfig(patch: Partial<RuntimeConfig>): RuntimeConfig {
    fs.mkdirSync(CONFIG_DIR, { recursive: true });
    const onDisk = normalizeRuntimeConfig(tryLoadRuntimeConfig() ?? {});
    const next = normalizeRuntimeConfig({ ...onDisk, ...patch });
    saveRuntimeConfig(next);
    return next;
}

function tryLoadRuntimeConfig(): Record<string, unknown> | null {
    if (!fs.existsSync(RUNTIME_CONFIG_PATH)) {
        return null;
    }

    try {
        const parsed = JSON.parse(fs.readFileSync(RUNTIME_CONFIG_PATH, 'utf8')) as unknown;
        return isObject(parsed) ? parsed : null;
    } catch {
        return null;
    }
}

function saveRuntimeConfig(config: RuntimeConfig): void {
    const temporaryPath = `${RUNTIME_CONFIG_PATH}.tmp-${String(process.pid)}`;

    try {
        fs.writeFileSync(temporaryPath, JSON.stringify(config, null, 2), 'utf8');
        fs.renameSync(temporaryPath, RUNTIME_CONFIG_PATH);
    } catch (error) {
        try {
            fs.unlinkSync(temporaryPath);
        } catch (cleanupError) {
            if (!isErrnoCode(cleanupError, 'ENOENT')) {
                throw new AggregateError(
                    [error, cleanupError],
                    'failed to persist runtime config and remove its temporary file',
                );
            }
        }

        throw error;
    }
}

/** True when the raw on-disk object already matches the normalized config
 *  on every known field (so we can skip a needless rewrite). */
function sameRuntimeConfig(parsed: Record<string, unknown>, n: RuntimeConfig): boolean {
    const parsedTls = isObject(parsed.webuiTls) ? parsed.webuiTls.enabled : undefined;
    return (
        parsed.webuiPort === n.webuiPort &&
        parsed.hookAutoLoad === n.hookAutoLoad &&
        parsed.webuiHost === n.webuiHost &&
        parsedTls === n.webuiTls?.enabled &&
        parsed.trustProxy === n.trustProxy &&
        parsed.logMaxTotalMb === n.logMaxTotalMb &&
        parsed.logRetainDays === n.logRetainDays &&
        parsed.logPerUin === n.logPerUin &&
        JSON.stringify(parsed.updateSource) === JSON.stringify(n.updateSource)
    );
}

function parsePortString(raw: unknown): number | undefined {
    if (typeof raw !== 'string' || !raw.trim()) {
        return undefined;
    }

    const n = Number(raw.trim());

    if (!Number.isFinite(n)) {
        return undefined;
    }

    const port = Math.trunc(n);

    if (port <= 0 || port > 65535) {
        return undefined;
    }

    return port;
}

function normalizeHost(value: unknown): string {
    if (typeof value === 'string' && value.trim()) {
        return value.trim();
    }

    return DEFAULT_WEBUI_HOST;
}

function normalizePort(value: unknown, fallback: number): number {
    if (typeof value === 'number' && Number.isFinite(value)) {
        const n = Math.trunc(value);

        if (n > 0 && n <= 65535) {
            return n;
        }

        return fallback;
    }

    if (typeof value === 'string' && value.trim()) {
        const n = Number(value);

        if (Number.isFinite(n)) {
            const port = Math.trunc(n);

            if (port > 0 && port <= 65535) {
                return port;
            }
        }
    }

    return fallback;
}

function normalizeRequiredInteger(
    value: unknown,
    fallback: number,
    min: number,
    max: number,
    field: string,
): number {
    if (value === undefined) {
        return fallback;
    }

    const n = typeof value === 'string' && value.trim() ? Number(value.trim()) : value;

    if (typeof n === 'number' && Number.isSafeInteger(n) && n >= min && n <= max) {
        return n;
    }

    throw new RangeError(`${field} must be an integer in ${String(min)}..${String(max)}`);
}

function normalizeRequiredBool(value: unknown, fallback: boolean, field: string): boolean {
    if (value === undefined) {
        return fallback;
    }

    const parsed = parseBoolValue(value);

    if (parsed !== undefined) {
        return parsed;
    }

    throw new TypeError(`${field} must be a boolean`);
}

function normalizeBool(value: unknown, fallback: boolean): boolean {
    if (typeof value === 'boolean') {
        return value;
    }

    if (typeof value === 'number') {
        return value !== 0;
    }

    if (typeof value === 'string') {
        const v = value.trim().toLowerCase();

        if (v === 'true' || v === '1' || v === 'yes' || v === 'on') {
            return true;
        }

        if (v === 'false' || v === '0' || v === 'no' || v === 'off' || v === '') {
            return false;
        }
    }

    return fallback;
}

function parseRequiredIntegerEnv(
    raw: unknown,
    min: number,
    max: number,
    field: string,
): number | undefined {
    if (typeof raw !== 'string' || !raw.trim()) {
        return undefined;
    }

    const n = Number(raw.trim());

    if (Number.isSafeInteger(n) && n >= min && n <= max) {
        return n;
    }

    throw new RangeError(`${field} must be an integer in ${String(min)}..${String(max)}`);
}

function parseRequiredBoolEnv(raw: unknown, field: string): boolean | undefined {
    if (typeof raw !== 'string' || !raw.trim()) {
        return undefined;
    }

    const parsed = parseBoolValue(raw);

    if (parsed !== undefined) {
        return parsed;
    }

    throw new TypeError(`${field} must be a boolean`);
}

function parseBoolValue(raw: unknown): boolean | undefined {
    if (typeof raw === 'boolean') {
        return raw;
    }

    if (raw === 1) {
        return true;
    }

    if (raw === 0) {
        return false;
    }

    if (typeof raw !== 'string') {
        return undefined;
    }

    const value = raw.trim().toLowerCase();

    if (value === 'true' || value === '1' || value === 'yes' || value === 'on') {
        return true;
    }

    if (value === 'false' || value === '0' || value === 'no' || value === 'off') {
        return false;
    }

    return undefined;
}

function isErrnoCode(error: unknown, code: string): boolean {
    return error instanceof Error && 'code' in error && error.code === code;
}