var sys = require('sys');

function Sqlite(path) {
  var conn = process.createChildProcess("sqlite3", ['-batch', '-header', '-nullvalue', "\r", '-separator', "\t", path]),
      queue = [], dequeued = 0,
      callback, want_close = false;

  function parse(string) {
    var raw, headers;
    // Parse the output into cells.  newline for row, tab for field, and
    // carriage return for null values.
    raw = string.split("\n").map(function (row) {
      return row.split("\t").map(function (item) {
        return item === "\r" ? null : item;
      });
    });

    // pop off the always trailing empty row
    raw.pop();

    // Strip off the first row, it's the column names
    headers = raw.shift();

    // Merge the rest into an array of json objects
    return raw.map(function (row) {
      var data = {};
      headers.map(function (name, index) {
        data[name] = row[index];
      });
      return data;
    });
  }

  function cycle(string) {
    // debug(queue.length);
    var next;

    // When we get data, call the callback and clear everything.
    if (string) {
      callback(string);
      callback = null;
    }

    // If the queue is empty, we're done
    if (queue.length === 0) {
      if (want_close) {
        conn.close();
      }
      return;
    }

    // If no query is active, insert another
    if (!callback) {

      // Use a delayed shift queue instead of shifting every time.
      next = queue[dequeued];
      dequeued += 1;
      if (dequeued * 2 > queue.length) {
        queue = queue.slice(dequeued);
        dequeued = 0;
      }

      callback = next[1];
      conn.write(next[0]);
    }
  }

  conn.addListener("output", cycle);

  conn.addListener("error", function (data) {
    if (data) {
      sys.puts('<span style="color:red">');
      sys.puts("ERROR: " + sys.inspect(data));
      sys.puts('<span style="color:red">');
    }
  });

  this.query = function (sql, cb) {
    queue.push([sql + ";\n", function (string) {
      cb(parse(string));
    }]);
    cycle();
  };

  this.command = function (command) {
    queue.push(["." + command + "\n", sys.puts]);
    cycle();
  };

  this.close = function () {
    want_close = true;
    cycle();
  };

}


var db = new Sqlite('test.db');
// db.command('schema');
for (var i = 0; i < 100000; i += 1) {
  db.query("SELECT * from reservations LIMIT 2", function () {});
}

db.close();