//
// Formatter for stats data.
//
module.exports = (function() {
  'use strict';

  // The blessed lib seems to leak memory when called multiple times,
  //   so use a singleton for blessed.program().
  var blessed = require('blessed');
  var program = null;

  var _ = require('lodash');
  _.str = require('underscore.string');
  _.mixin(_.str.exports());

  function Formatter(template) {
    if (!program) {
      program = blessed.program();
    }

    this.program = program;
    this.maxLines = 0;
    this.compileTemplate(template);
    this.startDraw();
  }

  Formatter.prototype.compileTemplate = function(lines) {
    this.template = lines;
    this.compiledTemplate = _.map(this.template, function(line) {
      return _.template(line);
    });
  };

  Formatter.prototype.startDraw = function() {
    this.lineCount = 0;
  };

  Formatter.prototype.draw = function(data) {
    this.startDraw();
    _.each(this.compiledTemplate, line => {
      this.writeLine(line(data));
    });
    this.endDraw();
  };

  Formatter.prototype.writeLine = function() {
    var str = Array.prototype.slice.call(arguments).join(' ');
    this.clearLine();
    this.program.write(_.truncate(str, this.safeLength() - 1, '…'));
    this.program.newline();
    this.lineCount++;
  };

  Formatter.prototype.endDraw =
  Formatter.prototype.rewind = function() {
    this.maxLines = Math.max(this.maxLines, this.lineCount);
    this.program.up(this.lineCount);
  };

  Formatter.prototype.clearAll = function() {
    for (var i = 0; i < this.maxLines; i++) {
      this.clearLine();
      this.program.newline();
    }
    this.program.up(this.maxLines);
  };

  Formatter.prototype.clearLine = function() {
    this.program.write(_.repeat(' ', this.safeLength()));
    this.program.newline();
    this.program.up(1);
  };

  Formatter.prototype.safeLength = function() {
    // Windows terminal will wrap to the next line if the last column
    //  is written to, so leave one column for a buffer.
    return this.program.cols - 1;
  };

  return Formatter;
})();