import { readSettingsFile } from './settings-io.js';

/** The `henyo` block of ~/.pi/agent/settings.json (always fully merged). */
export interface HenyoSettings {
  /** Standalone tool repair (event hooks only) + coaching + prompt guideline. */
  toolRepair: boolean;
  footer: boolean;
  agentsMd: boolean;
  /** Live TTFT/TPS working line during assistant streaming. */
  ttftTokps: boolean;
  /** ttft-tokps JSONL debug trace, off by default. */
  trace: boolean;
  /**
   * Fuzzy/nearest-match edit fallback (tool-repair layer): rewrites
   * whitespace-drifted `edits[].oldText` to file-exact bytes before execution
   * and enriches content-mismatch errors with nearest-match candidates /
   * occurrence line numbers. Event hooks only — built-in `edit` untouched.
   */
  editFallback: boolean;
  /**
   * Compaction summary retry guard: takes over summary generation on
   * `session_before_compact` with a strict plain-text prompt + up to 3
   * targeted retries; off by default.
   */
  compactionRetry: boolean;
  skills: Record<string, boolean>;
  commands: Record<string, boolean>;
}

export const DEFAULTS: HenyoSettings = {
  toolRepair: true,
  footer: true,
  agentsMd: true,
  ttftTokps: true,
  trace: false,
  editFallback: true,
  compactionRetry: false,
  skills: { plans: true, notes: true },
  commands: { cwd: true, newp: true },
};

export function isPlainObject(value: unknown): value is Record<string, any> {
  return value !== null && typeof value === 'object' && !Array.isArray(value);
}

/**
 * Merge the on-disk `henyo` block over DEFAULTS (nested `skills`/`commands`
 * merged key-by-key so a partial user block never hides default siblings).
 * Returns a fresh copy of the merged settings (module-level DEFAULTS is
 * never exposed or mutated) and whether the input was missing any of the
 * 13 known keys (`toolRepair`, `footer`, `agentsMd`,
 * `ttftTokps`, `trace`, `editFallback`, `compactionRetry`, skills×2,
 * commands×2) — values are never a write trigger.
 */
export function mergeHenyo(user: unknown): { henyo: HenyoSettings; changed: boolean } {
  const henyo: HenyoSettings = { ...DEFAULTS };
  if (!isPlainObject(user)) {
    henyo.skills = { ...DEFAULTS.skills };
    henyo.commands = { ...DEFAULTS.commands };
    return { henyo, changed: true };
  }
  const h = user as Partial<HenyoSettings>;
  henyo.toolRepair = h.toolRepair ?? DEFAULTS.toolRepair;
  henyo.footer = h.footer ?? DEFAULTS.footer;
  henyo.agentsMd = h.agentsMd ?? DEFAULTS.agentsMd;
  henyo.ttftTokps = h.ttftTokps ?? DEFAULTS.ttftTokps;
  henyo.trace = h.trace ?? DEFAULTS.trace;
  henyo.editFallback = h.editFallback ?? DEFAULTS.editFallback;
  henyo.compactionRetry = h.compactionRetry ?? DEFAULTS.compactionRetry;
  const userSkills = isPlainObject(h.skills) ? h.skills : {};
  const userCommands = isPlainObject(h.commands) ? h.commands : {};
  henyo.skills = { ...DEFAULTS.skills, ...userSkills };
  henyo.commands = { ...DEFAULTS.commands, ...userCommands };
  const knownKeys: (keyof HenyoSettings)[] = [
    'toolRepair',
    'footer',
    'agentsMd',
    'ttftTokps',
    'trace',
    'editFallback',
    'compactionRetry',
    'skills',
    'commands',
  ];
  const changed =
    knownKeys.some((key) => !(key in h)) ||
    Object.keys(DEFAULTS.skills).some((key) => !(key in userSkills)) ||
    Object.keys(DEFAULTS.commands).some((key) => !(key in userCommands));
  return { henyo, changed };
}

/**
 * Effective henyo settings (merged with defaults, user values preferred).
 * Read-only: never writes the settings file (use loadHenyoSettings from
 * index.ts for the fill-on-first-load behavior).
 */
export function getEffectiveHenyoSettings(): HenyoSettings {
  return mergeHenyo(readSettingsFile().henyo).henyo;
}