import fs from "node:fs";
import path from "node:path";
import { AppSettings, SessionState } from "../shared/types";
import { defaultSettings } from "./constants";
import { logger } from "./logger";

const VALID_PRIMARY_PROVIDERS = new Set(["realdebrid", "megadebrid", "bestdebrid", "alldebrid"]);
const VALID_FALLBACK_PROVIDERS = new Set(["none", "realdebrid", "megadebrid", "bestdebrid", "alldebrid"]);
const VALID_CLEANUP_MODES = new Set(["none", "trash", "delete"]);
const VALID_CONFLICT_MODES = new Set(["overwrite", "skip", "rename", "ask"]);
const VALID_FINISHED_POLICIES = new Set(["never", "immediate", "on_start", "package_done"]);
const VALID_SPEED_MODES = new Set(["global", "per_download"]);

function asText(value: unknown): string {
  return String(value ?? "").trim();
}

function clampNumber(value: unknown, fallback: number, min: number, max: number): number {
  const num = Number(value);
  if (!Number.isFinite(num)) {
    return fallback;
  }
  return Math.max(min, Math.min(max, Math.floor(num)));
}

export function normalizeSettings(settings: AppSettings): AppSettings {
  const defaults = defaultSettings();
  const normalized: AppSettings = {
    ...defaults,
    ...settings,
    token: asText(settings.token),
    megaLogin: asText(settings.megaLogin),
    megaPassword: asText(settings.megaPassword),
    bestToken: asText(settings.bestToken),
    allDebridToken: asText(settings.allDebridToken),
    rememberToken: Boolean(settings.rememberToken),
    autoProviderFallback: Boolean(settings.autoProviderFallback),
    outputDir: asText(settings.outputDir) || defaults.outputDir,
    packageName: asText(settings.packageName),
    autoExtract: Boolean(settings.autoExtract),
    extractDir: asText(settings.extractDir) || defaults.extractDir,
    createExtractSubfolder: Boolean(settings.createExtractSubfolder),
    hybridExtract: Boolean(settings.hybridExtract),
    removeLinkFilesAfterExtract: Boolean(settings.removeLinkFilesAfterExtract),
    removeSamplesAfterExtract: Boolean(settings.removeSamplesAfterExtract),
    enableIntegrityCheck: Boolean(settings.enableIntegrityCheck),
    autoResumeOnStart: Boolean(settings.autoResumeOnStart),
    autoReconnect: Boolean(settings.autoReconnect),
    maxParallel: clampNumber(settings.maxParallel, defaults.maxParallel, 1, 50),
    speedLimitEnabled: Boolean(settings.speedLimitEnabled),
    speedLimitKbps: clampNumber(settings.speedLimitKbps, defaults.speedLimitKbps, 0, 500000),
    reconnectWaitSeconds: clampNumber(settings.reconnectWaitSeconds, defaults.reconnectWaitSeconds, 10, 600),
    autoUpdateCheck: Boolean(settings.autoUpdateCheck),
    updateRepo: asText(settings.updateRepo) || defaults.updateRepo
  };

  if (!VALID_PRIMARY_PROVIDERS.has(normalized.providerPrimary)) {
    normalized.providerPrimary = defaults.providerPrimary;
  }
  if (!VALID_FALLBACK_PROVIDERS.has(normalized.providerSecondary)) {
    normalized.providerSecondary = "none";
  }
  if (!VALID_FALLBACK_PROVIDERS.has(normalized.providerTertiary)) {
    normalized.providerTertiary = "none";
  }
  if (!VALID_CLEANUP_MODES.has(normalized.cleanupMode)) {
    normalized.cleanupMode = defaults.cleanupMode;
  }
  if (!VALID_CONFLICT_MODES.has(normalized.extractConflictMode)) {
    normalized.extractConflictMode = defaults.extractConflictMode;
  }
  if (!VALID_FINISHED_POLICIES.has(normalized.completedCleanupPolicy)) {
    normalized.completedCleanupPolicy = defaults.completedCleanupPolicy;
  }
  if (!VALID_SPEED_MODES.has(normalized.speedLimitMode)) {
    normalized.speedLimitMode = defaults.speedLimitMode;
  }

  return normalized;
}

function sanitizeCredentialPersistence(settings: AppSettings): AppSettings {
  if (settings.rememberToken) {
    return settings;
  }
  return {
    ...settings,
    token: "",
    megaLogin: "",
    megaPassword: "",
    bestToken: "",
    allDebridToken: ""
  };
}

export interface StoragePaths {
  baseDir: string;
  configFile: string;
  sessionFile: string;
}

export function createStoragePaths(baseDir: string): StoragePaths {
  return {
    baseDir,
    configFile: path.join(baseDir, "rd_downloader_config.json"),
    sessionFile: path.join(baseDir, "rd_session_state.json")
  };
}

function ensureBaseDir(baseDir: string): void {
  fs.mkdirSync(baseDir, { recursive: true });
}

export function loadSettings(paths: StoragePaths): AppSettings {
  ensureBaseDir(paths.baseDir);
  if (!fs.existsSync(paths.configFile)) {
    return defaultSettings();
  }
  try {
    const parsed = JSON.parse(fs.readFileSync(paths.configFile, "utf8")) as AppSettings;
    const merged = normalizeSettings({
      ...defaultSettings(),
      ...parsed
    });
    return sanitizeCredentialPersistence(merged);
  } catch (error) {
    logger.error(`Konfiguration konnte nicht geladen werden: ${String(error)}`);
    return defaultSettings();
  }
}

export function saveSettings(paths: StoragePaths, settings: AppSettings): void {
  ensureBaseDir(paths.baseDir);
  const persisted = sanitizeCredentialPersistence(normalizeSettings(settings));
  const payload = JSON.stringify(persisted, null, 2);
  const tempPath = `${paths.configFile}.tmp`;
  fs.writeFileSync(tempPath, payload, "utf8");
  fs.renameSync(tempPath, paths.configFile);
}

export function emptySession(): SessionState {
  return {
    version: 2,
    packageOrder: [],
    packages: {},
    items: {},
    runStartedAt: 0,
    totalDownloadedBytes: 0,
    summaryText: "",
    reconnectUntil: 0,
    reconnectReason: "",
    paused: false,
    running: false,
    updatedAt: Date.now()
  };
}

export function loadSession(paths: StoragePaths): SessionState {
  ensureBaseDir(paths.baseDir);
  if (!fs.existsSync(paths.sessionFile)) {
    return emptySession();
  }
  try {
    const parsed = JSON.parse(fs.readFileSync(paths.sessionFile, "utf8")) as Partial<SessionState>;
    return {
      ...emptySession(),
      ...parsed,
      packages: parsed.packages ?? {},
      items: parsed.items ?? {},
      packageOrder: parsed.packageOrder ?? []
    };
  } catch (error) {
    logger.error(`Session konnte nicht geladen werden: ${String(error)}`);
    return emptySession();
  }
}

export function saveSession(paths: StoragePaths, session: SessionState): void {
  ensureBaseDir(paths.baseDir);
  const payload = JSON.stringify({ ...session, updatedAt: Date.now() }, null, 2);
  const tempPath = `${paths.sessionFile}.tmp`;
  fs.writeFileSync(tempPath, payload, "utf8");
  fs.renameSync(tempPath, paths.sessionFile);
}