/**
 * JSONL session store under BRIDGE_SWARM_STORAGE/agent/sessions/.
 */

const path = require('bare-path');
const fs = require('bare-fs');
const { ensureAgentRoot, ensureDir, sanitizeId } = require('../capabilities/paths.js');

function sessionsRoot() {
  return ensureDir(path.join(ensureAgentRoot(), 'sessions'));
}

function sessionDir(id) {
  return ensureDir(path.join(sessionsRoot(), sanitizeId(id)));
}

function readJsonl(file) {
  try {
    const raw = fs.readFileSync(file, 'utf8');
    return raw
      .split('\n')
      .map((l) => l.trim())
      .filter(Boolean)
      .map((l) => {
        try {
          return JSON.parse(l);
        } catch (_) {
          return null;
        }
      })
      .filter(Boolean);
  } catch (_) {
    return [];
  }
}

function appendJsonl(file, obj) {
  fs.appendFileSync(file, JSON.stringify(obj) + '\n');
}

function makeId() {
  return 'sess_' + Date.now().toString(36) + '_' + Math.random().toString(36).slice(2, 10);
}

function create(meta) {
  const id = meta.sessionId || makeId();
  const dir = sessionDir(id);
  const summary = {
    id,
    origin: meta.origin || '',
    cwd: meta.cwd || '',
    model: meta.model || '',
    title: meta.title || 'New session',
    hostWorkspace: meta.hostWorkspace !== false,
    workspace: meta.workspace || meta.cwd || '',
    builtinTools: meta.builtinTools,
    createdAt: Date.now(),
    updatedAt: Date.now(),
    plan: [],
    planMode: meta.planMode || { state: 'inactive', planPath: 'plan.md', reminderCount: 0 },
    goal: meta.goal || null,
  };
  fs.writeFileSync(path.join(dir, 'summary.json'), JSON.stringify(summary, null, 2));
  fs.writeFileSync(path.join(dir, 'chat_history.jsonl'), '');
  return summary;
}

function load(id) {
  const dir = sessionDir(id);
  let summary;
  try {
    summary = JSON.parse(fs.readFileSync(path.join(dir, 'summary.json'), 'utf8'));
  } catch (_) {
    throw new Error('session not found: ' + id);
  }
  summary.history = readJsonl(path.join(dir, 'chat_history.jsonl'));
  summary.updates = readJsonl(path.join(dir, 'updates.jsonl'));
  return summary;
}

function saveSummary(summary) {
  summary.updatedAt = Date.now();
  const copy = Object.assign({}, summary);
  delete copy.history;
  delete copy.updates;
  fs.writeFileSync(path.join(sessionDir(summary.id), 'summary.json'), JSON.stringify(copy, null, 2));
}

function appendHistory(id, msg) {
  appendJsonl(path.join(sessionDir(id), 'chat_history.jsonl'), Object.assign({ ts: Date.now() }, msg));
}

function appendUpdate(id, update) {
  appendJsonl(path.join(sessionDir(id), 'updates.jsonl'), Object.assign({ ts: Date.now() }, update));
}

function replaceHistory(id, history) {
  const file = path.join(sessionDir(id), 'chat_history.jsonl');
  const body = (history || []).map((m) => JSON.stringify(m)).join('\n');
  fs.writeFileSync(file, body ? body + '\n' : '');
}

function planFile(id) {
  return path.join(sessionDir(id), 'plan.md');
}

function readPlan(id) {
  try {
    return fs.readFileSync(planFile(id), 'utf8');
  } catch (_) {
    return '';
  }
}

function writePlan(id, text) {
  const file = planFile(id);
  fs.writeFileSync(file, String(text != null ? text : ''));
  return file;
}

function list() {
  const root = sessionsRoot();
  let names = [];
  try {
    names = fs.readdirSync(root);
  } catch (_) {
    return [];
  }
  const out = [];
  for (const name of names) {
    try {
      const summary = JSON.parse(fs.readFileSync(path.join(root, name, 'summary.json'), 'utf8'));
      out.push(summary);
    } catch (_) {}
  }
  out.sort((a, b) => (b.updatedAt || 0) - (a.updatedAt || 0));
  return out;
}

module.exports = {
  create,
  load,
  saveSummary,
  appendHistory,
  appendUpdate,
  replaceHistory,
  sessionDir,
  planFile,
  readPlan,
  writePlan,
  list,
  makeId,
};