import { cookies } from "next/headers";

export const SESSION_COOKIE_NAME = "popiart_session";

type ApiEnvelope<T> = {
  ok: boolean;
  data?: T;
  error?: {
    code?: string;
    message?: string;
    details?: unknown;
  };
};

export type PopiartUser = {
  id: string;
  email: string;
  name: string;
  scopes?: string[];
};

export type LoginResponse = {
  key: string;
  token: string;
  user: PopiartUser;
};

export type AuthSessionView = {
  user: PopiartUser;
  session_key?: string;
  upstream_key_masked?: string;
};

export type Skill = {
  id: string;
  name: string;
  description: string;
  tags: string[];
  version: string;
  model_type: string;
  route_key?: string;
  estimated_duration_s: number;
};

export type SkillListResponse = {
  items: Skill[];
  total: number;
  limit: number;
  offset: number;
};

export type BudgetSummary = {
  period: {
    start: string;
    end: string;
  };
  used: {
    tokens: number;
    cost_usd: number;
  };
  limit: {
    monthly_tokens: number;
    monthly_cost_usd: number;
  };
  remaining: {
    tokens: number;
    cost_usd: number;
  };
};

export type BudgetUsageRow = {
  dimension: string;
  tokens_used: number;
  cost_usd: number;
  job_count: number;
};

export type BudgetUsage = {
  rows: BudgetUsageRow[];
  total: {
    tokens_used: number;
    cost_usd: number;
    job_count: number;
  };
};

export class PopiartApiError extends Error {
  status: number;
  code?: string;
  details?: unknown;

  constructor(status: number, message: string, code?: string, details?: unknown) {
    super(message);
    this.name = "PopiartApiError";
    this.status = status;
    this.code = code;
    this.details = details;
  }
}

function stripTrailingSlash(value: string) {
  return value.replace(/\/+$/, "");
}

export function getPopiartEndpoint() {
  const configured =
    process.env.POPIART_ENDPOINT ??
    process.env.POPIART_SERVER_URL ??
    "http://127.0.0.1:8080/v1";
  return stripTrailingSlash(configured);
}

export function buildPopiartUrl(pathname: string) {
  const path = pathname.startsWith("/") ? pathname : `/${pathname}`;
  return `${getPopiartEndpoint()}${path}`;
}

async function readEnvelope<T>(response: Response) {
  try {
    return (await response.json()) as ApiEnvelope<T>;
  } catch {
    return null;
  }
}

export async function popiartFetchEnvelope<T>(pathname: string, init: RequestInit = {}) {
  const response = await fetch(buildPopiartUrl(pathname), {
    ...init,
    cache: "no-store",
  });
  const payload = await readEnvelope<T>(response);
  return { response, payload };
}

export async function popiartRequest<T>(
  pathname: string,
  options: {
    method?: string;
    body?: BodyInit | object;
    headers?: HeadersInit;
    token?: string;
  } = {},
) {
  const headers = new Headers(options.headers);
  let body: BodyInit | undefined;

  if (options.token) {
    headers.set("Authorization", `Bearer ${options.token}`);
  }

  if (options.body instanceof FormData || typeof options.body === "string") {
    body = options.body;
  } else if (options.body !== undefined) {
    headers.set("Content-Type", "application/json");
    body = JSON.stringify(options.body);
  }

  const { response, payload } = await popiartFetchEnvelope<T>(pathname, {
    method: options.method ?? (body ? "POST" : "GET"),
    headers,
    body,
  });

  if (!response.ok || !payload?.ok) {
    throw new PopiartApiError(
      response.status,
      payload?.error?.message ?? `Request failed with status ${response.status}`,
      payload?.error?.code,
      payload?.error?.details,
    );
  }

  return payload.data as T;
}

export async function getSessionToken() {
  const cookieStore = await cookies();
  return cookieStore.get(SESSION_COOKIE_NAME)?.value ?? null;
}

export async function getViewerSession() {
  const token = await getSessionToken();
  if (!token) {
    return null;
  }
  try {
    return await popiartRequest<AuthSessionView>("/auth/me", { token });
  } catch (error) {
    if (error instanceof PopiartApiError && error.status === 401) {
      return null;
    }
    throw error;
  }
}

export async function getSkillsCatalog(search?: string) {
  const token = await getSessionToken();
  if (!token) {
    return null;
  }
  const query = new URLSearchParams();
  query.set("limit", "100");
  if (search) {
    query.set("search", search);
  }
  return popiartRequest<SkillListResponse>(`/skills?${query.toString()}`, { token });
}

export async function getBudgetSummary() {
  const token = await getSessionToken();
  if (!token) {
    return null;
  }
  return popiartRequest<BudgetSummary>("/budget", { token });
}

export async function getBudgetUsage() {
  const token = await getSessionToken();
  if (!token) {
    return null;
  }
  return popiartRequest<BudgetUsage>("/budget/usage", { token });
}