/**
 * Chat dev logger.
 *
 * A thin namespaced wrapper over `consola` that no-ops in production unless
 * the host app explicitly opts in via `<ChatRoot debug />`. The default
 * detection uses `isDev` from `@djangocfg/ui-core/lib/env` (NODE_ENV).
 *
 * Why a dedicated module: chat is async and event-heavy (bootstrap, transport,
 * SSE chunks, tool calls, regenerate, …). Inline `console.log`s rot fast and
 * leak into prod. A single `getChatLogger()` call gives every layer the same
 * namespaced sub-logger and keeps zero-cost gating in one place.
 *
 * Sub-loggers:
 *   bootstrap  — initial session bootstrap (createSession / loadHistory)
 *   transport  — outbound transport calls + responses
 *   stream     — SSE chunk / tool / message_end events
 *   lifecycle  — sendMessage, regenerate, newSession, edits
 *   tools      — tool_call_start / _delta / _end specifics
 *   error      — caught errors (always emitted as `error` level)
 */
import { consola, type ConsolaInstance } from 'consola';

import { isDev } from '@djangocfg/ui-core/lib';

export type ChatLogScope =
  | 'bootstrap'
  | 'transport'
  | 'stream'
  | 'lifecycle'
  | 'tools'
  | 'error';

export interface ChatLogger {
  bootstrap: ConsolaInstance;
  transport: ConsolaInstance;
  stream: ConsolaInstance;
  lifecycle: ConsolaInstance;
  tools: ConsolaInstance;
  error: ConsolaInstance;
  /** True when this logger is actually emitting (host opted in or NODE_ENV=development). */
  enabled: boolean;
}

const SCOPES: ChatLogScope[] = [
  'bootstrap',
  'transport',
  'stream',
  'lifecycle',
  'tools',
  'error',
];

/** Module-level cache so all hooks/components share the same logger instance per `enabled` mode. */
const cache = new Map<boolean, ChatLogger>();

function buildLogger(enabled: boolean): ChatLogger {
  const root = consola.withTag('chat');
  const subs = Object.fromEntries(
    SCOPES.map((scope) => [scope, root.withTag(scope)]),
  ) as Record<ChatLogScope, ConsolaInstance>;

  if (!enabled) {
    // Silence everything except `error` — surfaced errors should never go
    // missing even if the host didn't opt in to debug logs.
    for (const scope of SCOPES) {
      if (scope === 'error') continue;
      subs[scope].level = -999;
    }
  }

  return { ...subs, enabled };
}

/**
 * Get the chat logger.
 * @param debug Explicit override from the host. `undefined` falls back to `isDev`.
 */
export function getChatLogger(debug?: boolean): ChatLogger {
  const enabled = debug ?? isDev;
  let logger = cache.get(enabled);
  if (!logger) {
    logger = buildLogger(enabled);
    cache.set(enabled, logger);
  }
  return logger;
}