/**
 * OpenCode Go usage / 限额 解析与展示。
 * 零 pi 依赖的纯业务模块。
 *
 * 实测：GET https://opencode.ai/zen/go/v1/usage
 *   { "usage": {
 *       "rolling": { "status": "ok", "percent": 11, "resetsAt": "..." },
 *       "weekly":  { "status": "ok", "percent": 4,  "resetsAt": "..." },
 *       "monthly": { "status": "ok", "percent": 2,  "resetsAt": "..." }
 *   } }
 * 只返回 percent + resetsAt（不返回美元明细）。
 */

export const OPENCODE_GO_USAGE_URL = "https://opencode.ai/zen/go/v1/usage";
export const OPENCODE_GO_USAGE_TIMEOUT_MS = 10_000;

export type UsageWindowStatus = "ok" | "rate-limited" | "unknown";

export interface UsageWindow {
  /** rolling(5h) / weekly / monthly */
  name: string;
  status: UsageWindowStatus;
  percent?: number;
  resetsAt?: string;
  startAt?: string;
  endAt?: string;
}

export interface UsageResponse {
  windows: UsageWindow[];
}

function isRecord(v: unknown): v is Record<string, unknown> {
  return typeof v === "object" && v !== null;
}

function readString(v: Record<string, unknown>, keys: string[]): string | undefined {
  for (const k of keys) {
    const x = v[k];
    if (typeof x === "string") return x;
  }
  return undefined;
}

function readNumber(v: Record<string, unknown>, keys: string[]): number | undefined {
  for (const k of keys) {
    const x = v[k];
    if (typeof x === "number") return x;
    if (typeof x === "string" && x.trim() !== "" && !isNaN(Number(x))) return Number(x);
  }
  return undefined;
}

export function parseUsageWindow(name: string, value: unknown): UsageWindow | undefined {
  if (!isRecord(value)) return undefined;
  const statusRaw = readString(value, ["status", "state"]);
  const status: UsageWindowStatus =
    statusRaw === "ok" || statusRaw === "active" ? "ok" : statusRaw === "rate-limited" ? "rate-limited" : "unknown";
  return {
    name,
    status,
    ...(readNumber(value, ["percent", "usagePercent", "usage_percent"]) !== undefined
      ? { percent: readNumber(value, ["percent", "usagePercent", "usage_percent"]) }
      : {}),
    ...(readString(value, ["resetsAt", "resetAt", "resets_at", "reset_at"]) !== undefined
      ? { resetsAt: readString(value, ["resetsAt", "resetAt", "resets_at", "reset_at"]) }
      : {}),
    ...(readString(value, ["startAt", "start_at"]) !== undefined ? { startAt: readString(value, ["startAt", "start_at"]) } : {}),
    ...(readString(value, ["endAt", "end_at"]) !== undefined ? { endAt: readString(value, ["endAt", "end_at"]) } : {}),
  };
}

/** 解析 usage 响应，兼容两种形态：{usage:{name:window}} 与 {windows:[...]}。 */
export function parseUsage(value: unknown): UsageResponse | undefined {
  if (!isRecord(value)) return undefined;
  const windows: UsageWindow[] = [];
  if (Array.isArray(value.windows)) {
    for (const w of value.windows) {
      if (!isRecord(w)) continue;
      const name = readString(w, ["name", "window", "period", "label"]) ?? "window";
      const parsed = parseUsageWindow(name, w);
      if (parsed) windows.push(parsed);
    }
    return { windows };
  }
  if (!isRecord(value.usage)) return undefined;
  for (const [name, window] of Object.entries(value.usage)) {
    const parsed = parseUsageWindow(name, window);
    if (parsed) windows.push(parsed);
  }
  return { windows };
}

export interface FetchLike {
  (url: string, init: {
    method: string;
    headers: Record<string, string>;
    signal?: AbortSignal;
  }): Promise<{ ok: boolean; status?: number; json(): Promise<unknown> }>;
}

export interface UsageFetchResult {
  ok: boolean;
  usage?: UsageResponse;
  message?: string;
}

export async function fetchUsage(
  bearerToken: string | undefined,
  fetchImpl: FetchLike = fetch as unknown as FetchLike,
  timeoutMs = OPENCODE_GO_USAGE_TIMEOUT_MS,
): Promise<UsageFetchResult> {
  if (!bearerToken) return { ok: false, message: "No API key configured." };
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), timeoutMs);
  try {
    const response = await fetchImpl(OPENCODE_GO_USAGE_URL, {
      method: "GET",
      headers: { Accept: "application/json", Authorization: `Bearer ${bearerToken}` },
      signal: controller.signal,
    });
    if (!response.ok) {
      return { ok: false, message: `Usage request failed with HTTP ${response.status ?? "?"}.` };
    }
    const usage = parseUsage(await response.json());
    if (!usage) return { ok: false, message: "Usage response did not match the expected OpenCode Go shape." };
    return { ok: true, usage };
  } catch (err) {
    if ((err as Error)?.name === "AbortError") return { ok: false, message: "Usage request timed out (10s)." };
    return { ok: false, message: "Usage request failed." };
  } finally {
    clearTimeout(timer);
  }
}

/** 判断 usage 里是否有被限流的窗口（配额耗尽信号）。 */
export function hasRateLimitedWindow(usage: UsageResponse): boolean {
  return usage.windows.some((w) => w.status === "rate-limited");
}

export function formatReset(iso?: string): string {
  if (!iso) return "?";
  const t = Date.parse(iso);
  if (isNaN(t)) return iso;
  return new Date(t).toLocaleString("zh-CN", { hour12: false });
}

export function formatUsageWindow(window: UsageWindow): string {
  const parts: string[] = [];
  if (window.percent !== undefined) parts.push(`${Math.round(window.percent)}% used`);
  if (window.status === "rate-limited") parts.push("RATE-LIMITED");
  const reset = window.resetsAt ? `reset ${formatReset(window.resetsAt)}` : window.endAt ? `end ${formatReset(window.endAt)}` : "";
  if (reset) parts.push(reset);
  return `${window.name}: ${parts.join(", ") || "n/a"}`;
}

// ---------------------------------------------------------------------------
// 多窗口进度条渲染（widget / footer 用）
// ---------------------------------------------------------------------------

/** 生成一段长度为 width 的 ASCII 进度条。percent 0-100。 */
export function progressBar(percent: number, width = 10): string {
  const p = Math.max(0, Math.min(100, percent));
  const filled = Math.round((p / 100) * width);
  return "▓".repeat(filled) + "░".repeat(width - filled);
}

export interface WindowBarConf {
  /** 警告阈值：任意窗口 percent >= 该值则标记 ⚠ */
  warnThreshold: number;
  /** reset 前提前量（天）：距 reset 小于等于该值则进入预警 */
  resetWarnDays: number;
}

export const DEFAULT_WINDOW_BAR_CONF: WindowBarConf = { warnThreshold: 80, resetWarnDays: 2 };

/** 进度条状态分级。 */
export type LevelStatus = "ok" | "warn" | "critical" | "limited";

/** 根据 percent 与 reset 时间判定窗口状态（含“提前 resetWarnDays 天警告”）。 */
export function windowStatus(w: UsageWindow | undefined, now: number, conf: WindowBarConf = DEFAULT_WINDOW_BAR_CONF): LevelStatus {
  if (!w) return "ok";
  if (w.status === "rate-limited") return "limited";
  const pct = w.percent ?? 0;
  const resetAt = w.resetsAt;
  let days = Infinity;
  if (resetAt) {
    const t = Date.parse(resetAt);
    if (!isNaN(t)) days = (t - now) / 86_400_000;
  }
  if (days <= 0 || pct >= 95) return "critical";
  if (pct >= conf.warnThreshold || days <= conf.resetWarnDays) return "warn";
  return "ok";
}

/** ANSI 真彩色码（widget/footer 嵌入用）。 */
export const ANSI = {
  ok: "\u001b[38;2;90;200;120m",
  warn: "\u001b[38;2;255;200;60m",
  critical: "\u001b[38;2;255;80;60m",
  limited: "\u001b[38;2;255;40;40m",
  dim: "\u001b[38;2;120;120;130m",
  reset: "\u001b[0m",
};

/** 包一层 ANSI 颜色（若带 color 标记）。 */
export function paint(text: string, status: LevelStatus, colored: boolean): string {
  if (!colored) return text;
  return `${ANSI[status]}${text}${ANSI.reset}`;
}

/** 一个 key 的三行进度条（rolling / weekly / monthly）。返回 string[]，每行一条。 */
export function keyWindowBars(
  keyName: string,
  windows: UsageWindow[],
  opts?: { active?: boolean; conf?: WindowBarConf; colored?: boolean; now?: number },
): string[] {
  const { active = false, conf = DEFAULT_WINDOW_BAR_CONF, colored = false, now = Date.now() } = opts ?? {};
  const byName = new Map<string, UsageWindow>();
  for (const w of windows) {
    const stem = (w.name || "").toLowerCase();
    if (stem.includes("roll")) byName.set("rolling", w);
    else if (stem.includes("week")) byName.set("weekly", w);
    else if (stem.includes("month")) byName.set("monthly", w);
    else byName.set(w.name, w);
  }
  const limited = windows.some((w) => w.status === "rate-limited");
  const title = paint(
    `${active ? "★" : "·"} ${keyName}${active ? " (active)" : ""}${limited ? " ⛔LIMITED" : ""}`,
    limited ? "limited" : "ok",
    colored,
  );
  return [
    title,
    windowBarRow("R", "5h", byName.get("rolling"), conf, colored, now),
    windowBarRow("W", "wk", byName.get("weekly"), conf, colored, now),
    windowBarRow("M", "mo", byName.get("monthly"), conf, colored, now),
  ];
}

function windowBarRow(label: string, shortName: string, w: UsageWindow | undefined, conf: WindowBarConf, colored: boolean, now: number): string {
  if (!w) return `${label} ${shortName}   n/a`;
  const pct = w.percent ?? 0;
  const status = windowStatus(w, now, conf);
  const mark = status !== "ok" ? " ⚠" : "";
  const pulse = w.status === "rate-limited" ? " [LIMITED]" : "";
  const reset = w.resetsAt ? formatResetShort(w.resetsAt) : w.endAt ? formatResetShort(w.endAt) : "--";
  const body = `${label} ${shortName} ${progressBar(pct)} ${String(Math.round(pct)).padStart(3)}%${mark}${pulse} reset ${reset}`;
  return paint(body, status, colored);
}

/** 紧凑时间：今天只显示 HH:MM，否则 MM-DD。 */
export function formatResetShort(iso?: string): string {
  if (!iso) return "--";
  const t = Date.parse(iso);
  if (isNaN(t)) return "--";
  const d = new Date(t);
  const now = new Date();
  if (d.toDateString() === now.toDateString()) {
    return d.toLocaleTimeString("zh-CN", { hour: "2-digit", minute: "2-digit", hour12: false });
  }
  return `${String(d.getMonth() + 1).padStart(2, "0")}-${String(d.getDate()).padStart(2, "0")}`;
}

/** footer 单行紧凑摘要：仅当前活跃 key 的 monthly 百分比。支持变色。 */
export function footerSummary(keyName: string, windows: UsageWindow[], opts?: { conf?: WindowBarConf; colored?: boolean; now?: number }): string {
  const { conf = DEFAULT_WINDOW_BAR_CONF, colored = false, now = Date.now() } = opts ?? {};
  const m = windows.find((w) => (w.name || "").toLowerCase().includes("month"));
  const pct = m?.percent ?? 0;
  const status = windows.length ? windowStatus(m, now, conf) : "ok";
  const days = m?.resetsAt ? Math.floor((Date.parse(m.resetsAt) - now) / 86_400_000) : Infinity;
  const countdown = Number.isFinite(days) && days <= conf.resetWarnDays ? ` ⏳${Math.max(0, Math.round(days))}d` : "";
  const body = `ocgo ${keyName} M${Math.round(pct)}%${countdown}${status !== "ok" ? " ⚠" : ""}`;
  return paint(body, status, colored);
}