"use strict";
var dateFormat = require('./date_format')
, os = require('os')
, eol = os.EOL || '\n'
, util = require('util')
, semver = require('semver')
, replacementRegExp = /%[sdj]/g
, layoutMakers = {
  "messagePassThrough": function() { return messagePassThroughLayout; },
  "basic": function() { return basicLayout; },
  "colored": function() { return colouredLayout; },
  "coloured": function() { return colouredLayout; },
  "pattern": function (config) {
    return patternLayout(config && config.pattern, config && config.tokens);
	},
  "dummy": function() { return dummyLayout; }
}
, colours = {
  ALL: "grey",
  TRACE: "blue",
  DEBUG: "cyan",
  INFO: "green",
  WARN: "yellow",
  ERROR: "red",
  FATAL: "magenta",
  OFF: "grey"
};

function wrapErrorsWithInspect(items) {
  return items.map(function(item) {
    if ((item instanceof Error) && item.stack) {
      return { inspect: function() {
        if (semver.satisfies(process.version, '>=6')) {
          return util.format(item);
        } else {
          return util.format(item) + '\n' + item.stack;
        }
      } };
    } else {
      return item;
    }
  });
}

function formatLogData(logData) {
  var data = logData;
  if (!Array.isArray(data)) {
    var numArgs = arguments.length;
    data = new Array(numArgs);
    for (var i = 0; i < numArgs; i++) {
      data[i] = arguments[i];
    }
  }
  return util.format.apply(util, wrapErrorsWithInspect(data));
}

var styles = {
    //styles
  'bold'      : [1,  22],
  'italic'    : [3,  23],
  'underline' : [4,  24],
  'inverse'   : [7,  27],
  //grayscale
  'white'     : [37, 39],
  'grey'      : [90, 39],
  'black'     : [90, 39],
  //colors
  'blue'      : [34, 39],
  'cyan'      : [36, 39],
  'green'     : [32, 39],
  'magenta'   : [35, 39],
  'red'       : [31, 39],
  'yellow'    : [33, 39]
};

function colorizeStart(style) {
  return style ? '\x1B[' + styles[style][0] + 'm' : '';
}
function colorizeEnd(style) {
  return style ? '\x1B[' + styles[style][1] + 'm' : '';
}
/**
 * Taken from masylum's fork (https://github.com/masylum/log4js-node)
 */
function colorize (str, style) {
  return colorizeStart(style) + str + colorizeEnd(style);
}

function timestampLevelAndCategory(loggingEvent, colour, timezoneOffest) {
  var output = colorize(
    formatLogData(
      '[%s] [%s] %s - '
      , dateFormat.asString(loggingEvent.startTime, timezoneOffest)
      , loggingEvent.level
      , loggingEvent.categoryName
    )
    , colour
  );
  return output;
}

/**
 * BasicLayout is a simple layout for storing the logs. The logs are stored
 * in following format:
 * <pre>
 * [startTime] [logLevel] categoryName - message\n
 * </pre>
 *
 * @author Stephan Strittmatter
 */
function basicLayout (loggingEvent, timezoneOffset) {
  return timestampLevelAndCategory(
    loggingEvent,
    undefined,
    timezoneOffset
  ) + formatLogData(loggingEvent.data);
}

/**
 * colouredLayout - taken from masylum's fork.
 * same as basicLayout, but with colours.
 */
function colouredLayout (loggingEvent, timezoneOffset) {
  return timestampLevelAndCategory(
    loggingEvent,
    colours[loggingEvent.level.toString()],
    timezoneOffset
  ) + formatLogData(loggingEvent.data);
}

function messagePassThroughLayout (loggingEvent) {
  return formatLogData(loggingEvent.data);
}

function dummyLayout(loggingEvent) {
  return loggingEvent.data[0];
}

/**
 * PatternLayout
 * Format for specifiers is %[padding].[truncation][field]{[format]}
 * e.g. %5.10p - left pad the log level by 5 characters, up to a max of 10
 * Fields can be any of:
 *  - %r time in toLocaleTimeString format
 *  - %p log level
 *  - %c log category
 *  - %h hostname
 *  - %m log data
 *  - %d date in various formats
 *  - %% %
 *  - %n newline
 *  - %z pid
 *  - %x{<tokenname>} add dynamic tokens to your log. Tokens are specified in the tokens parameter
 * You can use %[ and %] to define a colored block.
 *
 * Tokens are specified as simple key:value objects.
 * The key represents the token name whereas the value can be a string or function
 * which is called to extract the value to put in the log message. If token is not
 * found, it doesn't replace the field.
 *
 * A sample token would be: { "pid" : function() { return process.pid; } }
 *
 * Takes a pattern string, array of tokens and returns a layout function.
 * @param {String} Log format pattern String
 * @param {object} map object of different tokens
 * @param {number} timezone offset in minutes
 * @return {Function}
 * @author Stephan Strittmatter
 * @author Jan Schmidle
 */
function patternLayout (pattern, tokens, timezoneOffset) {
  // jshint maxstatements:22
  var TTCC_CONVERSION_PATTERN  = "%r %p %c - %m%n";
  var regex = /%(-?[0-9]+)?(\.?[0-9]+)?([\[\]cdhmnprzxy%])(\{([^\}]+)\})?|([^%]+)/;

  pattern = pattern || TTCC_CONVERSION_PATTERN;

  function categoryName(loggingEvent, specifier) {
    var loggerName = loggingEvent.categoryName;
    if (specifier) {
      var precision = parseInt(specifier, 10);
      var loggerNameBits = loggerName.split(".");
      if (precision < loggerNameBits.length) {
        loggerName = loggerNameBits.slice(loggerNameBits.length - precision).join(".");
      }
    }
    return loggerName;
  }

  function formatAsDate(loggingEvent, specifier) {
    var format = dateFormat.ISO8601_FORMAT;
    if (specifier) {
      format = specifier;
      // Pick up special cases
      if (format == "ISO8601") {
        format = dateFormat.ISO8601_FORMAT;
      } else if (format == "ISO8601_WITH_TZ_OFFSET") {
        format = dateFormat.ISO8601_WITH_TZ_OFFSET_FORMAT;
      } else if (format == "ABSOLUTE") {
        format = dateFormat.ABSOLUTETIME_FORMAT;
      } else if (format == "DATE") {
        format = dateFormat.DATETIME_FORMAT;
      }
    }
    // Format the date
    return dateFormat.asString(format, loggingEvent.startTime, timezoneOffset);
  }

  function hostname() {
    return os.hostname().toString();
  }

  function formatMessage(loggingEvent) {
    return formatLogData(loggingEvent.data);
  }

  function endOfLine() {
    return eol;
  }

  function logLevel(loggingEvent) {
    return loggingEvent.level.toString();
  }

  function startTime(loggingEvent) {
    return dateFormat.asString('hh:mm:ss', loggingEvent.startTime, timezoneOffset);
  }

  function startColour(loggingEvent) {
    return colorizeStart(colours[loggingEvent.level.toString()]);
  }

  function endColour(loggingEvent) {
    return colorizeEnd(colours[loggingEvent.level.toString()]);
  }

  function percent() {
    return '%';
  }

  function pid(loggingEvent) {
    if (loggingEvent && loggingEvent.pid) {
      return loggingEvent.pid;
    } else {
      return process.pid;
    }
  }

  function clusterInfo(loggingEvent, specifier) {
    if (loggingEvent.cluster && specifier) {
      return specifier
        .replace('%m', loggingEvent.cluster.master)
        .replace('%w', loggingEvent.cluster.worker)
        .replace('%i', loggingEvent.cluster.workerId);
    } else if (loggingEvent.cluster) {
      return loggingEvent.cluster.worker+'@'+loggingEvent.cluster.master;
    } else {
      return pid();
    }
  }

  function userDefined(loggingEvent, specifier) {
    if (typeof(tokens[specifier]) !== 'undefined') {
      if (typeof(tokens[specifier]) === 'function') {
        return tokens[specifier](loggingEvent);
      } else {
        return tokens[specifier];
      }
    }
    return null;
  }

  var replacers = {
    'c': categoryName,
    'd': formatAsDate,
    'h': hostname,
    'm': formatMessage,
    'n': endOfLine,
    'p': logLevel,
    'r': startTime,
    '[': startColour,
    ']': endColour,
    'y': clusterInfo,
    'z': pid,
    '%': percent,
    'x': userDefined
  };

  function replaceToken(conversionCharacter, loggingEvent, specifier) {
    return replacers[conversionCharacter](loggingEvent, specifier);
  }

  function truncate(truncation, toTruncate) {
    var len;
    if (truncation) {
      len = parseInt(truncation.substr(1), 10);
      return toTruncate.substring(0, len);
    }

    return toTruncate;
  }

  function pad(padding, toPad) {
    var len;
    if (padding) {
      if (padding.charAt(0) == "-") {
        len = parseInt(padding.substr(1), 10);
        // Right pad with spaces
        while (toPad.length < len) {
          toPad += " ";
        }
      } else {
        len = parseInt(padding, 10);
        // Left pad with spaces
        while (toPad.length < len) {
          toPad = " " + toPad;
        }
      }
    }
    return toPad;
  }

  function truncateAndPad(toTruncAndPad, truncation, padding) {
    var replacement = toTruncAndPad;
    replacement = truncate(truncation, replacement);
    replacement = pad(padding, replacement);
    return replacement;
  }

  return function(loggingEvent) {
    var formattedString = "";
    var result;
    var searchString = pattern;

    while ((result = regex.exec(searchString))) {
      var matchedString = result[0];
      var padding = result[1];
      var truncation = result[2];
      var conversionCharacter = result[3];
      var specifier = result[5];
      var text = result[6];

      // Check if the pattern matched was just normal text
      if (text) {
        formattedString += "" + text;
      } else {
        // Create a raw replacement string based on the conversion
        // character and specifier
        var replacement = replaceToken(conversionCharacter, loggingEvent, specifier);
        formattedString += truncateAndPad(replacement, truncation, padding);
      }
      searchString = searchString.substr(result.index + result[0].length);
    }
    return formattedString;
  };

}

module.exports = {
  basicLayout: basicLayout,
  messagePassThroughLayout: messagePassThroughLayout,
  patternLayout: patternLayout,
  colouredLayout: colouredLayout,
  coloredLayout: colouredLayout,
  dummyLayout: dummyLayout,
  addLayout: function(name, serializerGenerator) {
    layoutMakers[name] = serializerGenerator;
  },
  layout: function(name, config) {
    return layoutMakers[name] && layoutMakers[name](config);
  }
};
