/**
 * @file Automatic pricing for Claude models the dashboard has seen but has no
 * rate row of its own for. Every model id in `token_usage` is reduced to its
 * family (a `-YYYYMMDD` snapshot suffix dropped); a family with no
 * `<family>%` row is looked up in LiteLLM's public price list and INSERTED —
 * never updated, so a rate the user edited in Settings always wins. "Its own
 * row" is the test, not "some row matches": Opus 5.5 was silently priced as
 * Opus 5 by the broader `claude-opus-5%` pattern.
 *
 * The list is fetched only when something is missing, at most once per
 * CACHE_MS. Off with AGENTHUB_PRICING_SYNC=0|false|off.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const PRICE_LIST_URL =
  "https://raw.githubusercontent.com/BerriAI/litellm/main/model_prices_and_context_window.json";
const CHECK_MS = 15 * 60_000;
const CACHE_MS = 24 * 60 * 60_000;
/** A per-MTok rate above this is a parse error, not a price. */
const MAX_PER_MTOK = 1000;

let cached = null; // { at, list }

/** `claude-opus-5-5-20260101` → `claude-opus-5-5`; null for anything else. */
function familyOf(model) {
  if (typeof model !== "string") return null;
  const fam = model.replace(/-\d{8}$/, "");
  return /^claude-[a-z0-9-]+$/.test(fam) ? fam : null;
}

/** `claude-opus-5-5` → `Claude Opus 5.5`. */
function displayName(fam) {
  const [, ...parts] = fam.split("-");
  const words = [];
  const nums = [];
  for (const p of parts) (/^\d+$/.test(p) ? nums : words).push(p);
  const name = words.map((w) => w[0].toUpperCase() + w.slice(1)).join(" ");
  return `Claude ${name}${nums.length ? " " + nums.join(".") : ""}`;
}

/** One LiteLLM entry → a model_pricing row, or null when it is not usable. */
function toRow(fam, e) {
  if (!e || e.litellm_provider !== "anthropic") return null;
  const per = (v) => (typeof v === "number" ? v * 1e6 : NaN);
  const input = per(e.input_cost_per_token);
  const output = per(e.output_cost_per_token);
  // Anthropic's published multipliers stand in for a field the list omits.
  const read = per(e.cache_read_input_token_cost ?? e.input_cost_per_token * 0.1);
  const w5m = per(e.cache_creation_input_token_cost ?? e.input_cost_per_token * 1.25);
  const w1h = per(e.cache_creation_input_token_cost_above_1hr ?? e.input_cost_per_token * 2);
  const rates = [input, output, read, w5m, w1h];
  if (!rates.every((r) => Number.isFinite(r) && r >= 0 && r <= MAX_PER_MTOK)) return null;
  if (input === 0 && output === 0) return null;
  const fast = e.supports_fast_mode ? Number(e.provider_specific_entry?.fast) : 0;
  const fastOk = Number.isFinite(fast) && fast > 0 && fast <= 10;
  // Rounded: 0.000004 * 1e6 is 3.9999999999999996, which Settings would show.
  const r = (n) => Math.round(n * 1e6) / 1e6;
  return {
    pattern: `${fam}%`,
    name: displayName(fam),
    input: r(input),
    output: r(output),
    read: r(read),
    w5m: r(w5m),
    w1h: r(w1h),
    fastIn: fastOk ? r(input * fast) : 0,
    fastOut: fastOk ? r(output * fast) : 0,
  };
}

/** Families used in token_usage that have no `<family>%` row of their own. */
function missingFamilies(db) {
  const have = new Set(
    db
      .prepare("SELECT model_pattern FROM model_pricing")
      .all()
      .map((r) => r.model_pattern)
  );
  const out = new Set();
  for (const { model } of db.prepare("SELECT DISTINCT model FROM token_usage").all()) {
    const fam = familyOf(model);
    if (fam && !have.has(`${fam}%`)) out.add(fam);
  }
  return [...out];
}

async function defaultFetch() {
  const res = await fetch(PRICE_LIST_URL, { signal: AbortSignal.timeout(20_000) });
  if (!res.ok) throw new Error(`price list HTTP ${res.status}`);
  return res.json();
}

/**
 * One pass. Returns the patterns inserted. Never throws: pricing is a display
 * concern and a failed fetch must not reach the server's startup path.
 */
async function syncPricing(db, { fetchList = defaultFetch, now = Date.now() } = {}) {
  try {
    const missing = missingFamilies(db);
    if (missing.length === 0) return [];
    if (!cached || now - cached.at > CACHE_MS) cached = { at: now, list: await fetchList() };
    const insert = db.prepare(
      `INSERT OR IGNORE INTO model_pricing (model_pattern, display_name, input_per_mtok,
         output_per_mtok, cache_read_per_mtok, cache_write_per_mtok, cache_write_1h_per_mtok,
         fast_input_per_mtok, fast_output_per_mtok) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)`
    );
    const added = [];
    for (const fam of missing) {
      const row = toRow(fam, cached.list?.[fam]);
      if (!row) continue;
      const { changes } = insert.run(
        row.pattern,
        row.name,
        row.input,
        row.output,
        row.read,
        row.w5m,
        row.w1h,
        row.fastIn,
        row.fastOut
      );
      if (changes) added.push(row.pattern);
    }
    if (added.length) console.log(`[pricing] added rates for ${added.join(", ")}`);
    return added;
  } catch (err) {
    console.warn("[pricing] sync failed:", err.message);
    return [];
  }
}

function startPricingSync(db) {
  if (/^(0|false|off)$/i.test(process.env.AGENTHUB_PRICING_SYNC || "")) return;
  void syncPricing(db);
  setInterval(() => void syncPricing(db), CHECK_MS).unref();
}

function _resetCache() {
  cached = null;
}

module.exports = { syncPricing, startPricingSync, familyOf, displayName, toRow, _resetCache };