/**
 * Browser-side BFF client for the sādhana streak (/sadhna-streak).
 *
 * Mirrors lib/social.ts: same `/api/v1` base, same `credentials: "include"`
 * so the auth cookie rides along, same envelope unwrapping. Kept in its
 * own module so the streak feature doesn't bloat the social client.
 */

const BFF_BASE = process.env.NEXT_PUBLIC_BFF_URL || "http://localhost:8080";

export class SadhnaError extends Error {
  constructor(
    public status: number,
    message: string,
  ) {
    super(message);
    this.name = "SadhnaError";
  }
}

type Envelope<T> = {
  success: boolean;
  data?: T;
  error?: { code: number; message: string };
};

async function call<T>(path: string, init?: RequestInit): Promise<T> {
  const res = await fetch(`${BFF_BASE}/api/v1${path}`, {
    credentials: "include",
    headers: { "Content-Type": "application/json", ...(init?.headers ?? {}) },
    ...init,
  });
  if (res.status === 204) return undefined as T;
  const body = (await res.json().catch(() => ({}))) as Envelope<T>;
  if (!res.ok || body.success === false) {
    throw new SadhnaError(res.status, body.error?.message || res.statusText);
  }
  return (body.data ?? (undefined as unknown as T)) as T;
}

// ─── Types ───────────────────────────────────────────────────────────────

/** Plant growth stage, mirrors the BFF's stageFor(). */
export type SadhnaStage =
  | "dead"
  | "sprout"
  | "seedling"
  | "sapling"
  | "young"
  | "mature";

/** One cell of the 7-day streak strip. */
export type SadhnaDay = {
  date: string; // YYYY-MM-DD (UTC)
  chant_done: boolean;
  quote_done: boolean;
  completed: boolean;
};

/**
 * One fold of the sādhana creeper — a single day the vine has wound around
 * its pole. The vine grows a fresh fold for each day of the current streak
 * (oldest first); the final fold may be today, still in progress (the
 * growing tip). `rounds`/`posts` annotate what was offered that day.
 */
export type VineDay = {
  date: string; // YYYY-MM-DD (UTC)
  rounds: number;
  posts: number;
  completed: boolean;
  in_progress: boolean;
};

export type SadhnaDashboard = {
  // Today's two disciplines.
  target_rounds: number;
  rounds_completed: number;
  chant_done: boolean;
  quote_done: boolean;
  today_completed: boolean;
  // Streak counters.
  current_streak: number;
  longest_streak: number;
  // Plant state (growth 0–100).
  growth: number;
  stage: SadhnaStage;
  alive: boolean;
  // Trailing 7 days, oldest first.
  week: SadhnaDay[];
  // The creeper: one fold per day of the current streak (oldest first),
  // plus an in-progress fold for an unfinished today. Capped server-side;
  // current_streak holds the true length.
  vine_days: VineDay[];
  // Rewards. `next_reward_date` is the projected UTC date (YYYY-MM-DD) of the
  // next gift if the streak continues. `pending_reward` is a freshly earned
  // gift to celebrate now (null when there's nothing to show).
  next_reward_date: string | null;
  pending_reward: SadhnaRewardGrant | null;
};

/** A gift item in the streak-reward catalog. */
export type SadhnaReward = {
  id: string;
  key: string;
  name: string;
  meaning: string;
  image_url: string;
  active: boolean;
  sort: number;
};

/** A reward earned at a streak milestone (a multiple of 7 days). */
export type SadhnaRewardGrant = {
  milestone: number;
  granted_at: string;
  reward: SadhnaReward;
};

// ─── API ───────────────────────────────────────────────────────────────

export const sadhna = {
  /** Today's progress + streak + plant state. */
  dashboard: () => call<SadhnaDashboard>("/sadhna/dashboard"),

  /** Per-day state for an inclusive UTC date range (YYYY-MM-DD), for the
   *  calendar's week/month views. Range is bounded to a year server-side. */
  history: (from: string, to: string) =>
    call<SadhnaDay[]>(
      `/sadhna/history?from=${encodeURIComponent(from)}&to=${encodeURIComponent(to)}`,
    ),

  /** Save today's chanting round count; returns the recomputed dashboard. */
  saveChant: (roundsCompleted: number) =>
    call<SadhnaDashboard>("/sadhna/chant", {
      method: "POST",
      body: JSON.stringify({ rounds_completed: roundsCompleted }),
    }),

  /** The user's collected gifts (newest first) + giftable catalog size. */
  rewards: () =>
    call<{ collected: SadhnaRewardGrant[]; total: number }>("/sadhna/rewards"),

  /** Acknowledge pending celebrations after showing the confetti. */
  ackRewards: () => call<void>("/sadhna/rewards/ack", { method: "POST" }),

  // Reminder prefs moved to the notification matrix —
  // see `notifications.prefs()` in lib/social.ts.

  /** Report the browser's IANA timezone so reminders fire at local time. */
  setTimezone: (timezone: string) =>
    call<void>("/sadhna/timezone", {
      method: "POST",
      body: JSON.stringify({ timezone }),
    }),
};