/**
 * =============================================================================
 * QWHPI — Quebec Weekly Housing Price Index
 * Author  : Simon-Pierre Boucher
 * Contact : contact@spboucher.ai
 * File    : web/lib/api.ts
 * Purpose : Typed API client for the QHPI monthly FastAPI service.
 * =============================================================================
 */

export const API_BASE =
  process.env.NEXT_PUBLIC_API_URL ?? "http://localhost:8080";

export interface Observation {
  period: string;
  index: number | null;
  index_smoothed: number;
  representative_value: number | null;
  transactions: number;
  effective_sample_size: number | null;
  monthly_pct: number | null;
  three_month_pct: number | null;
  six_month_pct: number | null;
  yoy_pct: number | null;
  lower_95: number;
  upper_95: number;
  reliability_grade: string;
  shrinkage_weight: number | null;
  is_partial_month: boolean;
}

export interface SeriesResponse {
  geography: string;
  geography_name: string;
  geography_level: string;
  property_type: string;
  model_version: string;
  data_vintage: string;
  total_observations: number;
  observations: Observation[];
}

export interface LatestResponse {
  geography: string;
  geography_name: string;
  property_type: string;
  period: string;
  latest_index: number;
  representative_value: number | null;
  monthly_change: number | null;
  three_month_change: number | null;
  yoy_change: number | null;
  transactions: number;
  reliability: string;
  lower_95: number;
  upper_95: number;
  is_partial_month: boolean;
  data_vintage: string;
}

export interface GeographyNode {
  geography_id: string;
  geography_name: string;
  geography_level: string;
  property_types: string[];
}

export interface MapCell {
  geography_id: string;
  geography_name: string;
  value: number | null;
  reliability_grade: string;
  transactions: number;
}

async function get<T>(path: string): Promise<T> {
  const res = await fetch(`${API_BASE}${path}`, {
    headers: { Accept: "application/json" },
  });
  if (!res.ok) throw new Error(`${res.status} ${res.statusText} — ${path}`);
  return res.json() as Promise<T>;
}

export const fetchSeries = (g: string, t: string) =>
  get<SeriesResponse>(`/v1/index?geography=${g}&type=${t}`);

export const fetchLatest = (g: string, t: string) =>
  get<LatestResponse>(`/v1/index/latest?geography=${g}&type=${t}`);

export const fetchGeographies = () =>
  get<{ published_series: GeographyNode[]; data_vintage: string }>(
    "/v1/geographies",
  );

export const fetchMap = (metric: string, type: string, period?: string) =>
  get<{ metric: string; period: string; cells: MapCell[] }>(
    `/v1/map?metric=${metric}&level=region&type=${type}` +
      (period ? `&period=${period}` : ""),
  );

export const csvUrl = (g: string, t: string) =>
  `${API_BASE}/v1/index?geography=${g}&type=${t}&format=csv`;

export interface SeriesStats {
  geography: string;
  property_type: string;
  period: string;
  index: number;
  representative_value: number | null;
  lower_95: number;
  upper_95: number;
  reliability_grade: string;
  monthly_pct: number | null;
  three_month_pct: number | null;
  six_month_pct: number | null;
  yoy_pct: number | null;
  since_2021_pct: number;
  cagr_pct: number;
  peak_index: number;
  peak_period: string;
  drawdown_pct: number;
  months_since_peak: number;
  at_record_high: boolean;
  volatility_12m_pct: number;
  momentum_3m_ann_pct: number;
  yoy_rank: number | null;
  yoy_rank_of: number;
  volume_12m: number;
  volume_yoy_pct: number | null;
  dollar_volume_12m: number;
  assessment_gap: number | null;
  effective_sample_size: number | null;
  spark: number[];
}

export interface OverviewRow {
  geography_id: string;
  geography_name: string;
  period: string;
  index: number;
  monthly_pct: number | null;
  three_month_pct: number | null;
  six_month_pct: number | null;
  yoy_pct: number | null;
  since_2021_pct: number;
  drawdown_pct: number;
  at_record_high: boolean;
  volume_12m: number;
  representative_value: number | null;
  reliability_grade: string;
  spark: number[];
}

export const fetchStats = (g: string, t: string) =>
  get<SeriesStats>(`/v1/stats?geography=${g}&type=${t}`);

export const fetchOverview = (level: string, t: string) =>
  get<{ period: string; rows: OverviewRow[] }>(
    `/v1/stats/overview?level=${level}&type=${t}`,
  );

export const reportUrl = (specs: string[]) =>
  `${API_BASE}/v1/report?series=${specs.join(",")}`;

export const marketReportUrl = (t: string) =>
  `${API_BASE}/v1/report/market?type=${t}`;