import { Prisma } from "@toolctrl/db/prisma-browser";

export type AdminSettingsSection = "general" | "authentication" | "analytics" | "cookies";
export type AdminSettingsValidationErrors = Record<string, string[]>;

export type AdminSettingsValidationResult =
  | { ok: true; section: AdminSettingsSection; data: Prisma.AppConfigurationUpdateInput }
  | { ok: false; status: 400; errors: AdminSettingsValidationErrors };

const MAX_SHORT_TEXT_LENGTH = 255;
const MAX_SCRIPT_LENGTH = 20_000;
const MAX_BRANDING_VALUE_LENGTH = 10_000;
const EMAIL_PATTERN = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
// EU-Sterilisation (R-P1a): googleAnalyticsTrackingId aus den Admin-Analytics-Settings entfernt.
const SECRET_FIELD_NAMES = new Set(["headScripts", "bodyScripts"]);

export function parseAdminSettingsForm(section: AdminSettingsSection, form: FormData): AdminSettingsValidationResult {
  const errors: AdminSettingsValidationErrors = {};
  const action = getString(form, "action");
  if (action !== "update") {
    addError(errors, "action", "Invalid action.");
    return invalid(errors);
  }

  switch (section) {
    case "general":
      return parseGeneralSettings(form, errors);
    case "authentication":
      return parseAuthenticationSettings(form, errors);
    case "analytics":
      return parseAnalyticsSettings(form, errors);
    case "cookies":
      return parseCookiesSettings(form, errors);
    default:
      addError(errors, "section", "Invalid settings section.");
      return invalid(errors);
  }
}

export function redactSettingsAuditDetails(section: AdminSettingsSection, input: Prisma.AppConfigurationUpdateInput): string {
  const details = {
    section,
    changedFields: Object.keys(input).sort(),
    values: Object.fromEntries(
      Object.entries(input)
        .sort(([left], [right]) => left.localeCompare(right))
        .map(([field, value]) => [field, redactFieldValue(field, value)])
    ),
  };

  return JSON.stringify(details).slice(0, 4_000);
}

function parseGeneralSettings(form: FormData, errors: AdminSettingsValidationErrors): AdminSettingsValidationResult {
  const name = requireString(form, "name", errors);
  const theme = optionalString(form, "theme", errors);
  const logo = optionalString(form, "logo", errors, MAX_BRANDING_VALUE_LENGTH);
  const logoDarkMode = optionalString(form, "logoDarkMode", errors, MAX_BRANDING_VALUE_LENGTH);
  const icon = optionalString(form, "icon", errors, MAX_BRANDING_VALUE_LENGTH);
  const iconDarkMode = optionalString(form, "iconDarkMode", errors, MAX_BRANDING_VALUE_LENGTH);
  const favicon = optionalString(form, "favicon", errors, MAX_BRANDING_VALUE_LENGTH);
  const headScripts = optionalString(form, "headScripts", errors, MAX_SCRIPT_LENGTH);
  const bodyScripts = optionalString(form, "bodyScripts", errors, MAX_SCRIPT_LENGTH);

  if (Object.keys(errors).length > 0) {
    return invalid(errors);
  }

  return valid("general", {
    name,
    brandingLogo: logo,
    brandingLogoDarkMode: logoDarkMode,
    brandingIcon: icon,
    brandingIconDarkMode: iconDarkMode,
    brandingFavicon: favicon,
    theme,
    headScripts,
    bodyScripts,
  });
}

function parseAuthenticationSettings(form: FormData, errors: AdminSettingsValidationErrors): AdminSettingsValidationResult {
  if (Object.keys(errors).length > 0) {
    return invalid(errors);
  }

  return valid("authentication", {
    authRequireEmailVerification: getBoolean(form, "requireEmailVerification"),
    authRequireOrganization: getBoolean(form, "requireOrganization"),
    authRequireName: getBoolean(form, "requireName"),
    subscriptionRequired: getBoolean(form, "required"),
    subscriptionAllowSubscribeBeforeSignUp: getBoolean(form, "allowSubscribeBeforeSignUp"),
    subscriptionAllowSignUpBeforeSubscribe: getBoolean(form, "allowSignUpBeforeSubscribe"),
  });
}

function parseAnalyticsSettings(form: FormData, errors: AdminSettingsValidationErrors): AdminSettingsValidationResult {
  if (Object.keys(errors).length > 0) {
    return invalid(errors);
  }

  return valid("analytics", {
    analyticsEnabled: getBoolean(form, "enabled"),
    analyticsSimpleAnalytics: getBoolean(form, "simpleAnalytics"),
    analyticsPlausibleAnalytics: getBoolean(form, "plausibleAnalytics"),
  });
}

function parseCookiesSettings(form: FormData, errors: AdminSettingsValidationErrors): AdminSettingsValidationResult {
  const enabled = getOptionalBoolean(form, "enabled", errors);
  if (Object.keys(errors).length > 0) {
    return invalid(errors);
  }

  return valid("cookies", {
    cookiesEnabled: enabled,
  });
}

function requireString(form: FormData, field: string, errors: AdminSettingsValidationErrors, maxLength = MAX_SHORT_TEXT_LENGTH) {
  const value = optionalString(form, field, errors, maxLength);
  if (!value) {
    addError(errors, field, "This field is required.");
  }
  return value;
}

function optionalString(form: FormData, field: string, errors: AdminSettingsValidationErrors, maxLength = MAX_SHORT_TEXT_LENGTH) {
  const value = getString(form, field).trim();
  if (value.length > maxLength) {
    addError(errors, field, `Must be ${maxLength} characters or fewer.`);
  }
  if (field.toLowerCase().includes("email") && value && !EMAIL_PATTERN.test(value)) {
    addError(errors, field, "Email address is invalid.");
  }
  return value;
}

function getString(form: FormData, field: string) {
  const value = form.get(field);
  return typeof value === "string" ? value : "";
}

function getBoolean(form: FormData, field: string) {
  const value = form.get(field);
  return value === "on" || value === "true" || value === "1";
}

function getOptionalBoolean(form: FormData, field: string, errors: AdminSettingsValidationErrors) {
  const value = form.get(field);
  if (value === null) {
    return false;
  }
  if (value === "on" || value === "true" || value === "1") {
    return true;
  }
  if (value === "off" || value === "false" || value === "0") {
    return false;
  }
  addError(errors, field, "Boolean value is invalid.");
  return false;
}

function addError(errors: AdminSettingsValidationErrors, field: string, message: string) {
  errors[field] = [...(errors[field] ?? []), message];
}

function invalid(errors: AdminSettingsValidationErrors): AdminSettingsValidationResult {
  return { ok: false, status: 400, errors };
}

function valid(section: AdminSettingsSection, data: Prisma.AppConfigurationUpdateInput): AdminSettingsValidationResult {
  return { ok: true, section, data };
}

function redactFieldValue(field: string, value: unknown) {
  if (typeof value === "boolean") {
    return value;
  }
  if (typeof value === "string") {
    if (SECRET_FIELD_NAMES.has(field) || isSensitiveFieldName(field)) {
      return { redacted: true, length: value.length, source: value ? "provided" : "empty" };
    }
    if (looksLikeUrl(value)) {
      return { redacted: true, source: "url", origin: safeUrlOrigin(value), hasQuery: hasUrlQuery(value) };
    }
    return { redacted: true, length: value.length, source: value ? "provided" : "empty" };
  }
  if (value === null || value === undefined) {
    return { source: "empty" };
  }
  return { redacted: true, source: "complex" };
}

function isSensitiveFieldName(field: string) {
  return /token|password|secret|key|script|tracking|url/i.test(field);
}

function looksLikeUrl(value: string) {
  return /^https?:\/\//i.test(value);
}

function safeUrlOrigin(value: string) {
  try {
    return new URL(value).origin;
  } catch {
    return "invalid-url";
  }
}

function hasUrlQuery(value: string) {
  try {
    return new URL(value).search.length > 0;
  } catch {
    return false;
  }
}