import * as fs from "fs";
import * as path from "path";

const REPO_ROOT = process.env.REPO_ROOT || path.resolve(process.cwd(), "..");
const USAGE_LOG = path.join(REPO_ROOT, "apps/palacemonitor", "usage.jsonl");

export interface UsageEntry {
  channel: string;
  model?: string;
  domain?: string;
  duration_ms: number;
  total_cost_usd: number;
  input_tokens: number;
  output_tokens: number;
  cache_read_input_tokens: number;
  cache_creation_input_tokens: number;
  num_turns: number;
}

export function logUsage(entry: UsageEntry): void {
  const now = new Date();
  const date = now.toLocaleDateString("en-CA", { timeZone: "America/Los_Angeles" });
  const time = now.toLocaleTimeString("en-US", {
    timeZone: "America/Los_Angeles",
    hour12: false,
    hour: "2-digit",
    minute: "2-digit",
  });

  const row: Record<string, any> = {
    date,
    time,
    channel: entry.channel,
    model: entry.model || "opus",
    duration_min: Math.round(entry.duration_ms / 60000),
    duration_ms: entry.duration_ms,
    tokens_in: entry.input_tokens + entry.cache_read_input_tokens + entry.cache_creation_input_tokens,
    tokens_out: entry.output_tokens,
    cost_usd: entry.total_cost_usd,
    num_turns: entry.num_turns,
  };
  if (entry.domain) row.domain = entry.domain;

  try {
    fs.appendFileSync(USAGE_LOG, JSON.stringify(row) + "\n");
  } catch (err) {
    console.error("[usage] failed to log:", err);
  }
}

export function extractUsageFromResult(msg: any): Omit<UsageEntry, "channel" | "model" | "domain"> {
  return {
    duration_ms: msg.duration_ms || 0,
    total_cost_usd: msg.total_cost_usd || 0,
    input_tokens: msg.usage?.input_tokens || 0,
    output_tokens: msg.usage?.output_tokens || 0,
    cache_read_input_tokens: msg.usage?.cache_read_input_tokens || 0,
    cache_creation_input_tokens: msg.usage?.cache_creation_input_tokens || 0,
    num_turns: msg.num_turns || 0,
  };
}