import { toolRepairExtension, resolveToolRepair, resolveEditFallback } from './tool-repair.js';
import { ttftTokpsExtension } from './ttft-tokps.js';
import { compactionRetryExtension } from './compaction-retry.js';
import { getAgentDir } from '@earendil-works/pi-coding-agent';
import type {
  ExtensionAPI as _ExtensionAPI,
  ExtensionContext,
} from '@earendil-works/pi-coding-agent';
import type { TUI } from '@earendil-works/pi-tui';
import { join, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';
import fs from 'node:fs';
import cwdCommand from './commands/cwd.js';
import newpCommand from './commands/newp.js';
import henyoCommand from './commands/henyo.js';
import { FooterFactory } from './footer.js';
import { readSettingsFile, writeSettingsFile } from './settings-io.js';
import { mergeHenyo } from './henyo-settings.js';
import type { HenyoSettings } from './henyo-settings.js';

const __dirname = dirname(fileURLToPath(import.meta.url));

/** Resolve a path relative to this extension's installed location. */
function extPath(...segments: string[]) {
  return join(__dirname, '..', ...segments);
}

const SKILLS = { plans: 'skills/plans', notes: 'skills/notes' };

const COMMANDS: Record<
  string,
  (pi: _ExtensionAPI, applyFooter: (enabled: boolean) => void) => void
> = {
  cwd: cwdCommand,
  newp: newpCommand,
};

/**
 * Load henyo settings from ~/.pi/agent/settings.json. Never throws.
 * Returns the merged settings in memory (all defaults filled in, user
 * values preferred). When the on-disk `henyo` block is missing keys —
 * first install, or an upgrade that added features — a single write adds
 * the missing keys with their defaults; existing keys and values are never
 * modified (steady state = zero writes).
 */
export function loadHenyoSettings(): HenyoSettings {
  try {
    const settings = readSettingsFile();
    const { henyo, changed } = mergeHenyo(settings.henyo);
    if (changed) {
      writeSettingsFile({ ...settings, henyo });
    }
    return henyo;
  } catch {
    return mergeHenyo(undefined).henyo;
  }
}

/**
 * henyo-pi-core extension entry point.
 *
 * This factory function is called by pi when loading the extension.
 * Return a Promise for async initialization (runs before session_start).
 */
export default function (pi: _ExtensionAPI) {
  // ─── Henyo settings ──────────────────────────────────────────────────
  const henyoSettings = loadHenyoSettings();

  // ─── Tool repair (event hooks only — coexists with tool overrides) ──
  const toolRepairEnabled = resolveToolRepair(henyoSettings);
  if (toolRepairEnabled) {
    toolRepairExtension(pi, {
      enabled: true,
      editFallbackEnabled: resolveEditFallback(henyoSettings),
    });
  }

  // ─── TTFT/TPS working line (config-gated display + opt-in trace) ────
  if (henyoSettings.ttftTokps !== false) {
    ttftTokpsExtension(pi, { traceEnabled: henyoSettings.trace === true });
  }

  // ─── Compaction retry guard (off by default) ──────────────────────────
  // Takes over session_before_compact summary generation: strict plain-text
  // prompt + up to 3 targeted retries; falls back to pi's default compaction.
  if (henyoSettings.compactionRetry === true) {
    compactionRetryExtension(pi);
  }

  // ─── Event subscriptions ───────────────────────────────────────────
  const enabledSkillPaths = Object.entries(SKILLS)
    .filter(([name]) => henyoSettings.skills[name] !== false)
    .map(([, path]) => extPath(path));

  if (enabledSkillPaths.length > 0) {
    pi.on('resources_discover', async (_event, _ctx) => {
      return { skillPaths: enabledSkillPaths };
    });
  }

  let footerTui: TUI | undefined;
  let sessionCtx: ExtensionContext | undefined;

  /**
   * Apply the custom footer (or clear it) on the current session.
   * Used by session_start and by the /henyo footer toggle.
   */
  function applyFooter(enabled: boolean): void {
    const ctx = sessionCtx;
    if (!ctx) return; // no active session yet — nothing to attach to
    if (!ctx.hasUI) return; // non-TUI mode — no footer UI to attach to
    if (enabled) {
      ctx.ui.setFooter((_tui, _theme, footerData) => {
        footerTui = _tui;
        return FooterFactory(_tui, _theme, footerData, ctx, () => pi.getThinkingLevel());
      });
    } else {
      ctx.ui.setFooter(undefined);
    }
  }

  // ─── Lazy init: copy SAMPLE_GLOBAL_AGENTS.md on first session ────
  let agentsMdCopied = false;
  async function ensureAgentsMd() {
    if (agentsMdCopied) return;
    agentsMdCopied = true;
    const src = extPath('SAMPLE_GLOBAL_AGENTS.md');
    const agentDir = getAgentDir();
    const dst = join(agentDir, 'AGENTS.md');
    try {
      if (!fs.existsSync(dst) && fs.existsSync(src)) {
        fs.mkdirSync(agentDir, { recursive: true });
        fs.copyFileSync(src, dst);
      }
    } catch {
      // Silently fail — don't break sessions if copy fails
    }
  }

  pi.on('session_start', async (_event, ctx) => {
    sessionCtx = ctx;
    if (henyoSettings.agentsMd !== false) {
      await ensureAgentsMd();
    }
    // Set the custom footer component
    applyFooter(henyoSettings.footer !== false);
  });

  // Re-render footer when model changes
  pi.on('model_select', () => {
    footerTui?.requestRender();
  });

  // Re-render footer when the thinking level changes (suffix is part of line 1)
  pi.on('thinking_level_select', () => {
    footerTui?.requestRender();
  });

  // Re-render footer when session info changes (e.g. session name prefix)
  pi.on('session_info_changed', () => {
    footerTui?.requestRender();
  });

  // ─── Custom commands ───────────────────────────────────────────────
  // /henyo is always registered — user-facing control; must not be gated
  // behind settings (a gated entry point could be disabled, leaving no TUI
  // path to re-enable it).
  henyoCommand(pi, applyFooter);

  for (const [cmdName, register] of Object.entries(COMMANDS)) {
    if (henyoSettings.commands[cmdName] !== false) {
      register(pi, applyFooter);
    }
  }
}