session.ts

// Uses Node.js 22+ built-in sqlite — no native compilation, no npm package required
import { DatabaseSync } from "node:sqlite";
import { createHash } from "node:crypto";
import { mkdirSync, existsSync, readFileSync } from "node:fs";
import { join } from "node:path";
import { Config } from "./config.js";
import { runMigrations } from "./migrations.js";
import { projectHash as scopedProjectHash } from "./store.js";

export type EventType = "file_write" | "file_edit" | "task_complete" | "error" | "fetch" | "session_ended";

export interface SessionEvent {
  event_type: EventType;
  file_path?: string;
  task_name?: string;
  error_type?: string;
  created_at?: string;
  // SECURITY: No content/output fields — we never store file contents or command output
}

function getEventLogPath(projectPath: string): string {
  const hash = scopedProjectHash(projectPath);
  return join(Config.DB_DIR, `${hash}.events.jsonl`);
}

function dbPath(projectPath: string): string {
  const hash = scopedProjectHash(projectPath);
  return join(Config.DB_DIR, `${hash}.db`);
}

function openDb(projectPath: string): DatabaseSync {
  mkdirSync(Config.DB_DIR, { recursive: true });
  const db = new DatabaseSync(dbPath(projectPath));

  // WAL mode for concurrent multi-agent access + busy wait instead of immediate fail
  db.exec("PRAGMA journal_mode = WAL");
  db.exec("PRAGMA busy_timeout = 5000");

  db.exec(`
    CREATE TABLE IF NOT EXISTS sessions (
      id           INTEGER PRIMARY KEY AUTOINCREMENT,
      project_hash TEXT    NOT NULL,
      created_at   TEXT    NOT NULL,
      last_active  TEXT    NOT NULL
    );

    CREATE TABLE IF NOT EXISTS events (
      id          INTEGER PRIMARY KEY AUTOINCREMENT,
      session_id  INTEGER NOT NULL,
      event_type  TEXT    NOT NULL,
      file_path   TEXT,
      task_name   TEXT,
      error_type  TEXT,
      created_at  TEXT    NOT NULL,
      FOREIGN KEY(session_id) REFERENCES sessions(id)
    );
  `);

  // Apply all pending schema migrations
  runMigrations(db);

  return db;
}



export function getRecentEvents(projectPath: string, limit = 50): SessionEvent[] {
  // Read from the JSONL event log written by hooks (posttooluse.mjs, stop.mjs).
  // Hooks write minimal metadata events; this is the source of truth for zc_recall_context().
  const logPath = getEventLogPath(projectPath);
  if (!existsSync(logPath)) return [];

  try {
    const lines = readFileSync(logPath, "utf8").split("\n").filter(Boolean);
    return lines
      .slice(-limit)
      .reverse()
      .map((line) => {
        try { return JSON.parse(line) as SessionEvent; }
        catch { return null; }
      })
      .filter((e): e is SessionEvent => e !== null);
  } catch {
    return [];
  }
}