import type { Context, Next } from "hono";
import { deleteCookie, getCookie, setCookie } from "hono/cookie";
import { withIamTenant, findUserByUsernameAnyTenant } from "./iam_db.ts";
import { getPlatformDb } from "./platform_db.ts";
import { config } from "./config.ts";
import { createSession, getSession, revokeSession, revokeAllSessionsForUser } from "./sessions.ts";
import { hashPassword, verifyPassword } from "./crypto.ts";

export type AuthRealm = "app" | "platform";

export type AuthUser = {
  id: number;
  username: string;
  display_name: string;
  company_id: number | null;
  company_code: string | null;
  company_name: string | null;
  company_kind: string | null;
  tenant_id: number | null;
  role_id: number | null;
  role_code: string;
  is_owner: boolean;
  status: string;
  realm: AuthRealm;
  must_change_password: boolean;
};

const COOKIE = "po_session";
const TTL_SECONDS = 60 * 60 * 24 * 7;

const USER_SELECT = `
  SELECT u.id, u.username, u.password_hash, u.display_name, u.company_id, u.tenant_id,
    u.role_id, r.code AS role_code, r.is_system AS role_is_system, r.tenant_id AS role_tenant_id,
    u.status, u.must_change_password, u.email
  FROM users u
  JOIN roles r ON r.id = u.role_id
  WHERE u.id = ?`;

export async function createSessionCookie(
  c: Context,
  userId: number,
  realm: AuthRealm = "app",
  tenantId: number | null = null,
) {
  const id = await createSession(userId, realm, tenantId);
  setCookie(c, COOKIE, id, {
    httpOnly: true,
    path: "/",
    sameSite: "Lax",
    secure: config.cookieSecure,
    maxAge: TTL_SECONDS,
  });
}

export async function clearSession(c: Context) {
  const id = getCookie(c, COOKIE);
  if (id) await revokeSession(id);
  deleteCookie(c, COOKIE, { path: "/" });
}

function isOwnerRole(row: Record<string, unknown>): boolean {
  return row.role_code === "tenant_admin"
    && Boolean(row.role_is_system)
    && row.role_tenant_id == null;
}

function asAppUser(row: Record<string, unknown>): AuthUser {
  return {
    id: Number(row.id),
    username: String(row.username),
    display_name: String(row.display_name),
    company_id: row.company_id == null ? null : Number(row.company_id),
    company_code: (row.company_code as string | null) ?? null,
    company_name: (row.company_name as string | null) ?? null,
    company_kind: (row.company_kind as string | null) ?? null,
    tenant_id: row.tenant_id == null ? null : Number(row.tenant_id),
    role_id: row.role_id == null ? null : Number(row.role_id),
    role_code: String(row.role_code ?? "user"),
    is_owner: isOwnerRole(row),
    status: String(row.status ?? "activo"),
    realm: "app",
    must_change_password: Boolean(row.must_change_password),
  };
}

function asPlatformUser(row: { id: number; username: string; display_name: string }): AuthUser {
  return {
    id: row.id,
    username: row.username,
    display_name: row.display_name,
    company_id: null,
    company_code: null,
    company_name: null,
    company_kind: null,
    tenant_id: null,
    role_id: null,
    role_code: "platform_admin",
    is_owner: true,
    status: "activo",
    realm: "platform",
    must_change_password: false,
  };
}

async function userFromCookie(c: Context): Promise<AuthUser | null> {
  const id = getCookie(c, COOKIE);
  if (!id) return null;
  const session = await getSession(id);
  if (!session) return null;

  if (session.realm === "platform") {
    const pdb = await getPlatformDb();
    const row = await pdb.prepare(
      `SELECT id, username, display_name FROM platform_users
       WHERE id = ? AND status = 'activo'`,
    ).get(session.userId) as { id: number; username: string; display_name: string } | undefined;
    return row ? asPlatformUser(row) : null;
  }

  return await getFreshAppUser(session.userId, session.tenantId);
}

/** Relee un usuario app (iam) fresco de la base y lo enriquece con su
 * empresa (core) -- usado tras login y tras cambiar contraseña. */
export async function getFreshAppUser(userId: number, tenantId: number | null): Promise<AuthUser | null> {
  const row = await withIamTenant(tenantId, async (db) => {
    return await db.prepare(USER_SELECT).get(userId);
  });
  if (!row) return null;
  if (String(row.status ?? "activo") !== "activo") return null;
  const company = await enrichWithCompanyViaCore((row.company_id as number) ?? null);
  return asAppUser({ ...row, ...company });
}

function apiKeyOk(c: Context): boolean {
  if (!config.apiKey) return false;
  const header = c.req.header("x-api-key") ?? "";
  if (header.length !== config.apiKey.length) return false;
  let diff = 0;
  for (let i = 0; i < header.length; i++) diff |= header.charCodeAt(i) ^ config.apiKey.charCodeAt(i);
  return diff === 0;
}

export async function requireAuth(c: Context, next: Next) {
  if (apiKeyOk(c)) {
    const tenantHeader = c.req.header("x-tenant-id") ?? "";
    const tenantId = Number(tenantHeader);
    if (!tenantHeader || !Number.isInteger(tenantId) || tenantId <= 0) {
      return c.json({ error: "X-API-Key requiere X-Tenant-Id" }, 400);
    }
    c.set("user", {
      id: 0,
      username: "api",
      display_name: "API Key",
      company_id: null,
      company_code: null,
      company_name: null,
      company_kind: null,
      tenant_id: tenantId,
      role_id: null,
      role_code: "api_key",
      is_owner: false,
      status: "activo",
      realm: "app",
      must_change_password: false,
    } satisfies AuthUser);
    await next();
    return;
  }
  const user = await userFromCookie(c);
  if (!user) return c.json({ error: "No autenticado" }, 401);
  c.set("user", user);
  await next();
}

export async function requirePlatformAdmin(c: Context, next: Next) {
  const user = await userFromCookie(c);
  if (!user) return c.json({ error: "No autenticado" }, 401);
  if (user.realm !== "platform" || user.role_code !== "platform_admin") {
    return c.json({ error: "Solo administradores SaaS" }, 403);
  }
  c.set("user", user);
  await next();
}

export function tenantScope(user: AuthUser): number | null {
  if (user.realm === "platform") return null;
  return user.tenant_id;
}

export async function login(username: string, password: string): Promise<AuthUser | null> {
  const user = username.trim();
  const pass = password.trim();
  if (!user || !pass) return null;

  const appRow = await findUserByUsernameAnyTenant(user);
  if (appRow && await verifyPassword(pass, appRow.password_hash as string)) {
    if (String(appRow.status ?? "activo") !== "activo") {
      throw Object.assign(new Error("Usuario dado de baja"), { code: "USER_INACTIVE" });
    }
    const authUser = await withIamTenant(
      appRow.tenant_id == null ? null : Number(appRow.tenant_id),
      async () => {
        const company = await enrichWithCompanyViaCore(Number(appRow.company_id) || null);
        return asAppUser({ ...appRow, ...company });
      },
    );
    const pdb = await getPlatformDb();
    const { tenantAccessBlocked } = await import("./saas.ts");
    const blocked = await tenantAccessBlocked(pdb, authUser.tenant_id);
    if (blocked) {
      throw Object.assign(new Error(blocked), { code: "TENANT_BLOCKED" });
    }
    return authUser;
  }

  const pdb = await getPlatformDb();
  const plat = await pdb.prepare(
    `SELECT id, username, display_name, password_hash FROM platform_users
     WHERE username = ? AND status = 'activo'`,
  ).get(user) as
    | { id: number; username: string; display_name: string; password_hash: string }
    | undefined;
  if (plat && await verifyPassword(pass, plat.password_hash)) {
    return asPlatformUser(plat);
  }
  return null;
}

/** company_id de iam.users es una referencia lógica a core.companies(id)
 * (sin FK -- esquemas aislados). Esta función vive en auth.ts para no
 * crear un import cruzado iam<->core; usa la conexión core con el rol de
 * runtime normal (companies no está sujeta a RLS por-fila salvo por
 * tenant_id, así que basta con conocer el tenant ya resuelto). */
async function enrichWithCompanyViaCore(companyId: number | null) {
  if (companyId == null) return { company_code: null, company_name: null, company_kind: null };
  const { getCoreDb } = await import("./db.ts");
  const db = await getCoreDb();
  const row = await db.prepare("SELECT code, name, kind FROM companies WHERE id = ?").get(
    companyId,
  );
  return {
    company_code: (row?.code as string) ?? null,
    company_name: (row?.name as string) ?? null,
    company_kind: (row?.kind as string) ?? null,
  };
}

export async function changePassword(
  userId: number,
  tenantId: number | null,
  currentPassword: string,
  newPassword: string,
): Promise<{ error?: string }> {
  const next = (newPassword ?? "").trim();
  if (next.length < 8) return { error: "La nueva contraseña debe tener al menos 8 caracteres" };
  return await withIamTenant(tenantId, async (db) => {
    const row = await db.prepare("SELECT password_hash FROM users WHERE id = ?").get(userId) as
      | { password_hash: string }
      | undefined;
    if (!row) return { error: "Usuario no encontrado" };
    if (!await verifyPassword(currentPassword, row.password_hash)) {
      return { error: "Contraseña actual incorrecta" };
    }
    const hash = await hashPassword(next);
    await db.prepare(
      "UPDATE users SET password_hash = ?, must_change_password = false WHERE id = ?",
    ).run(hash, userId);
    await revokeAllSessionsForUser(userId, "app");
    return {};
  });
}