/**
 * earth-now.co
 * Author:  Simon-Pierre Boucher
 * Contact: contact@spboucher.ai
 * File:    apps/web/lib/api.ts
 * Purpose: Typed fetchers + MetricSummary type mirroring the apps/api REST contract (/v1/metrics, /v1/models, /v1/rt/quakes)
 */

import type { CounterModel } from "@earth-now/counter";

export type Locale = "fr" | "en";

export interface LocalizedText {
  fr: string;
  en: string;
}

export type MetricDomain =
  | "population"
  | "climate"
  | "emissions"
  | "forest"
  | "ocean"
  | "energy"
  | "society"
  | "health"
  | "economy"
  | "tech"
  | "realtime"
  | "space";

export type MetricKind = "stock" | "cumulative" | "event" | "derived";

export type ModelLevel = 0 | 1 | 2 | "rt" | "derived";

export type DerivedOp =
  | "linear-combination"
  | "window"
  | "rate-of"
  | "depletion-countdown";

export interface MetricSource {
  id: string;
  name: string;
  url: string;
  license: string;
  cadence: string;
}

export interface MetricDisplay {
  decimals: number;
  sigFigs?: number;
  scale?: number;
  unit: LocalizedText;
}

export interface DerivedSpec {
  op: DerivedOp;
  inputs: Array<{ id: string; weight: number }>;
  constant?: number;
  window?: "today" | "ytd" | "session";
}

export interface MetricSummary {
  id: string;
  name: LocalizedText;
  domain: MetricDomain;
  priority: string;
  kind: MetricKind;
  level: ModelLevel;
  model: string;
  unit: string;
  sources: MetricSource[];
  display: MetricDisplay;
  windows: string[];
  derived?: DerivedSpec;
  uncertaintyFraction?: number;
  editorialNote?: LocalizedText;
  stale: boolean;
  modelVersion?: string;
  observedAt?: string;
}

export interface ModelsResponse {
  models: Record<string, CounterModel>;
  generatedAt: string;
}

export interface QuakesResponse {
  count24h: number;
  lastMajor: { mag: number; place: string; timeIso: string } | null;
  fetchedAt: string;
}

/**
 * API base URL. Client-side: NEXT_PUBLIC_API_URL (inlined at build time).
 * Server-side: API_URL takes precedence, then NEXT_PUBLIC_API_URL.
 */
export function apiBase(): string {
  if (typeof window === "undefined") {
    return (
      process.env.API_URL ?? process.env.NEXT_PUBLIC_API_URL ?? "http://localhost:4000"
    );
  }
  return process.env.NEXT_PUBLIC_API_URL ?? "http://localhost:4000";
}

async function getJson<T>(path: string): Promise<T> {
  const res = await fetch(`${apiBase()}${path}`, { cache: "no-store" });
  if (!res.ok) throw new Error(`API ${path} responded ${res.status}`);
  return (await res.json()) as T;
}

export async function fetchMetrics(): Promise<MetricSummary[]> {
  return getJson<MetricSummary[]>("/v1/metrics");
}

export async function fetchModels(): Promise<ModelsResponse> {
  return getJson<ModelsResponse>("/v1/models");
}

export async function fetchQuakes(): Promise<QuakesResponse> {
  return getJson<QuakesResponse>("/v1/rt/quakes");
}

/** SSE stream URL — subscribed with EventSource in the client dashboard. */
export function sseStreamUrl(): string {
  return `${apiBase()}/sse/stream`;
}