import fs from 'node:fs';
import path from 'node:path';
import Database from 'better-sqlite3';

export function openDb(sqlitePath) {
  const dir = path.dirname(sqlitePath);
  fs.mkdirSync(dir, { recursive: true });
  const db = new Database(sqlitePath);
  db.pragma('journal_mode = WAL');
  db.pragma('synchronous = NORMAL');
  db.pragma('foreign_keys = ON');
  migrate(db);
  return db;
}

function migrate(db) {
  db.exec(`
    CREATE TABLE IF NOT EXISTS chat_log (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      request_id TEXT NOT NULL UNIQUE,
      chat_id TEXT,
      ts_request INTEGER NOT NULL,
      ts_first_token INTEGER,
      ts_done INTEGER,
      model TEXT NOT NULL,
      messages_json TEXT NOT NULL,
      user_text TEXT,
      assistant_text TEXT,
      prompt_tokens INTEGER,
      completion_tokens INTEGER,
      total_tokens INTEGER,
      status TEXT NOT NULL,
      error TEXT,
      ip TEXT,
      user_agent TEXT
    );

    CREATE INDEX IF NOT EXISTS idx_chat_log_ts_request ON chat_log(ts_request DESC);
    CREATE INDEX IF NOT EXISTS idx_chat_log_chat_ts ON chat_log(chat_id, ts_request DESC);
    CREATE INDEX IF NOT EXISTS idx_chat_log_model_ts ON chat_log(model, ts_request DESC);
    CREATE INDEX IF NOT EXISTS idx_chat_log_status_ts ON chat_log(status, ts_request DESC);
  `);

  // FTS5 (prompt+answer search)
  // content_rowid = chat_log.id
  db.exec(`
    CREATE VIRTUAL TABLE IF NOT EXISTS chat_log_fts USING fts5(
      user_text,
      assistant_text,
      content='chat_log',
      content_rowid='id'
    );
  `);

  db.exec(`
    CREATE TRIGGER IF NOT EXISTS chat_log_ai AFTER INSERT ON chat_log BEGIN
      INSERT INTO chat_log_fts(rowid, user_text, assistant_text)
      VALUES (new.id, coalesce(new.user_text,''), coalesce(new.assistant_text,''));
    END;
    CREATE TRIGGER IF NOT EXISTS chat_log_ad AFTER DELETE ON chat_log BEGIN
      INSERT INTO chat_log_fts(chat_log_fts, rowid, user_text, assistant_text)
      VALUES('delete', old.id, old.user_text, old.assistant_text);
    END;
    CREATE TRIGGER IF NOT EXISTS chat_log_au AFTER UPDATE ON chat_log BEGIN
      INSERT INTO chat_log_fts(chat_log_fts, rowid, user_text, assistant_text)
      VALUES('delete', old.id, old.user_text, old.assistant_text);
      INSERT INTO chat_log_fts(rowid, user_text, assistant_text)
      VALUES (new.id, coalesce(new.user_text,''), coalesce(new.assistant_text,''));
    END;
  `);
}

export function prepareQueries(db) {
  const insertStart = db.prepare(`
    INSERT INTO chat_log (
      request_id, chat_id, ts_request, model, messages_json, user_text,
      status, ip, user_agent
    ) VALUES (
      @request_id, @chat_id, @ts_request, @model, @messages_json, @user_text,
      @status, @ip, @user_agent
    )
  `);

  const markFirstToken = db.prepare(`
    UPDATE chat_log
      SET ts_first_token = coalesce(ts_first_token, @ts_first_token)
      WHERE request_id = @request_id
  `);

  const finish = db.prepare(`
    UPDATE chat_log
      SET
        ts_done = @ts_done,
        assistant_text = @assistant_text,
        prompt_tokens = @prompt_tokens,
        completion_tokens = @completion_tokens,
        total_tokens = @total_tokens,
        status = @status,
        error = @error
      WHERE request_id = @request_id
  `);

  const getByRequestId = db.prepare(`
    SELECT * FROM chat_log WHERE request_id = ?
  `);

  return {
    insertStart,
    markFirstToken,
    finish,
    getByRequestId,
  };
}