import { POLICY_CAPS } from "../config/defaults.js";
import { derivedRate, estimateCredits, resolveCatalog, usableUsdCost, type UsdModelCost } from "./price-catalog.js";
import type { Policy, PriceCatalog } from "../types.js";

/** The nominal call the budget governor sizes a spawn against: 8k in, 800 out. */
const NOMINAL_INPUT_TOKENS = 8_000;
const NOMINAL_OUTPUT_TOKENS = 800;

export type PriceCoverageKind = "declared" | "free" | "derived" | "missing";

export interface PriceCoverage {
  model: string;
  kind: PriceCoverageKind;
  creditsPerCall?: number;
  callsPerTask?: number;
}

/**
 * How each declared model gets a price, and what that price buys.
 *
 * The calls-per-task column is the point of this: it is what tells someone with a Sonnet-first
 * roster, at install time, that `balanced` buys them five turns — instead of meeting the number
 * later as a spawn refusal in the middle of a task.
 */
export function priceCoverage(tiers: readonly string[], catalog: PriceCatalog, costOf: (model: string) => UsdModelCost | undefined, policy: Policy): PriceCoverage[] {
  const stopTarget = POLICY_CAPS[policy].internalStopTarget;
  return tiers.map((model): PriceCoverage => {
    const declared = catalog.models[model];
    const cost = declared ? undefined : costOf(model);
    const rate = declared ?? (usableUsdCost(cost) ? derivedRate(cost, catalog.creditsPerUsd) : undefined);
    if (!rate) return { model, kind: "missing" };
    const priced = resolveCatalog(catalog, new Map([[model, rate]]));
    const creditsPerCall = estimateCredits(priced, model, NOMINAL_INPUT_TOKENS, 0, NOMINAL_OUTPUT_TOKENS);
    const kind: PriceCoverageKind = declared ? (creditsPerCall === 0 ? "free" : "declared") : "derived";
    return { model, kind, creditsPerCall, callsPerTask: creditsPerCall > 0 ? Math.floor(stopTarget / creditsPerCall) : undefined };
  });
}

export function formatPriceCoverage(rows: readonly PriceCoverage[], catalog: PriceCatalog, policy: Policy): string[] {
  const failed = rows.some((row) => row.kind === "missing");
  const width = Math.max(0, ...rows.map((row) => row.model.length));
  return [
    `price-catalog-coverage=${failed ? "FAIL" : "PASS"} creditsPerUsd=${catalog.creditsPerUsd ?? "unset"} tiers=${rows.length}`,
    ...rows.map((row) => row.kind === "missing"
      ? `  ${row.model.padEnd(width)}  missing   no usable cost in the catalogue or the Pi model registry — add an entry or drop the tier`
      : `  ${row.model.padEnd(width)}  ${row.kind.padEnd(8)}  ${row.creditsPerCall!.toFixed(2)} credits/call  ${row.callsPerTask === undefined ? "unmetered" : `~${row.callsPerTask} calls at ${policy}`}`),
  ];
}