// Suivi d'usage et budgets : plafonds quotidiens/mensuels par utilisateur + budget global,
// appliqués côté serveur AVANT chaque appel de modèle.

import { get, getSetting, run } from "./db/index.ts";

export type BudgetConfig = {
  dailyPerUserUSD: number;
  monthlyPerUserUSD: number;
  monthlyGlobalUSD: number;
  dailyRequestsPerUser: number;
};

export const DEFAULT_BUDGETS: BudgetConfig = {
  dailyPerUserUSD: 1.5,
  monthlyPerUserUSD: 15,
  monthlyGlobalUSD: 200,
  dailyRequestsPerUser: 200,
};

export function getBudgets(): BudgetConfig {
  return { ...DEFAULT_BUDGETS, ...getSetting<Partial<BudgetConfig>>("budgets", {}) };
}

export function checkBudget(userId: number): { ok: boolean; reason?: string } {
  const b = getBudgets();
  const day = get<{ c: number; n: number }>(
    "SELECT COALESCE(SUM(cost),0) as c, COUNT(*) as n FROM usage_log WHERE user_id = ? AND created_at >= datetime('now','start of day')",
    userId
  );
  if ((day?.n ?? 0) >= b.dailyRequestsPerUser)
    return { ok: false, reason: "Limite quotidienne de requêtes atteinte. Réessayez demain." };
  if ((day?.c ?? 0) >= b.dailyPerUserUSD)
    return { ok: false, reason: "Budget quotidien atteint. Réessayez demain ou choisissez un modèle économique." };
  const month = get<{ c: number }>(
    "SELECT COALESCE(SUM(cost),0) as c FROM usage_log WHERE user_id = ? AND created_at >= datetime('now','start of month')",
    userId
  );
  if ((month?.c ?? 0) >= b.monthlyPerUserUSD) return { ok: false, reason: "Budget mensuel personnel atteint." };
  const global = get<{ c: number }>(
    "SELECT COALESCE(SUM(cost),0) as c FROM usage_log WHERE created_at >= datetime('now','start of month')"
  );
  if ((global?.c ?? 0) >= b.monthlyGlobalUSD)
    return { ok: false, reason: "Budget global de la plateforme atteint ce mois-ci. Contactez le professeur." };
  return { ok: true };
}

export function logUsage(opts: {
  userId: number;
  model: string;
  kind?: string;
  tokensIn: number;
  tokensOut: number;
  cost: number;
  latencyMs: number;
  ok?: boolean;
  error?: string;
}) {
  run(
    "INSERT INTO usage_log (user_id, model, kind, tokens_in, tokens_out, cost, latency_ms, ok, error) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)",
    opts.userId, opts.model, opts.kind ?? "chat", opts.tokensIn, opts.tokensOut, opts.cost, opts.latencyMs, opts.ok === false ? 0 : 1, opts.error ?? null
  );
}

export function logActivity(userId: number, kind: string, courseCode?: string | null, durationS = 0, meta: unknown = {}) {
  run(
    "INSERT INTO activity_log (user_id, kind, course_code, duration_s, meta) VALUES (?, ?, ?, ?, ?)",
    userId, kind, courseCode ?? null, durationS, JSON.stringify(meta)
  );
}