/*!
 * Stylus - SourceMapper
 * Copyright (c) Automattic <developer.wordpress.com>
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

var Compiler = require('./compiler')
  , SourceMapGenerator = require('source-map').SourceMapGenerator
  , basename = require('path').basename
  , extname = require('path').extname
  , dirname = require('path').dirname
  , join = require('path').join
  , relative = require('path').relative
  , sep = require('path').sep
  , fs = require('fs');

/**
 * Initialize a new `SourceMapper` generator with the given `root` Node
 * and the following `options`.
 *
 * @param {Node} root
 * @api public
 */

var SourceMapper = module.exports = function SourceMapper(root, options){
  options = options || {};
  this.column = 1;
  this.lineno = 1;
  this.contents = {};
  this.filename = options.filename;
  this.dest = options.dest;

  var sourcemap = options.sourcemap;
  this.basePath = sourcemap.basePath || '.';
  this.inline = sourcemap.inline;
  this.comment = sourcemap.comment;
  if (extname(this.dest) === '.css') {
    this.basename = basename(this.dest);
  } else {
    this.basename = basename(this.filename, extname(this.filename)) + '.css';
  }
  this.utf8 = false;

  this.map = new SourceMapGenerator({
    file: this.basename,
    sourceRoot: sourcemap.sourceRoot || null
  });
  Compiler.call(this, root, options);
};

/**
 * Inherit from `Compiler.prototype`.
 */

SourceMapper.prototype.__proto__ = Compiler.prototype;

/**
 * Generate and write source map.
 *
 * @return {String}
 * @api private
 */

var compile = Compiler.prototype.compile;
SourceMapper.prototype.compile = function(){
  var css = compile.call(this)
    , out = this.basename + '.map'
    , url = this.normalizePath(this.dest
      ? join(this.dest, out)
      : join(dirname(this.filename), out))
    , map;

  if (this.inline) {
    map = this.map.toString();
    url = 'data:application/json;'
      + (this.utf8 ?  'charset=utf-8;' : '') + 'base64,'
      + new Buffer(map).toString('base64');
  }
  if (this.inline || false !== this.comment)
    css += '/*# sourceMappingURL=' + url + ' */';
  return css;
};

/**
 * Add mapping information.
 *
 * @param {String} str
 * @param {Node} node
 * @return {String}
 * @api private
 */

SourceMapper.prototype.out = function(str, node){
  if (node && node.lineno) {
    var filename = this.normalizePath(node.filename);

    this.map.addMapping({
      original: {
        line: node.lineno,
        column: node.column - 1
      },
      generated: {
        line: this.lineno,
        column: this.column - 1
      },
      source: filename
    });

    if (this.inline && !this.contents[filename]) {
      this.map.setSourceContent(filename, fs.readFileSync(node.filename, 'utf-8'));
      this.contents[filename] = true;
    }
  }

  this.move(str);
  return str;
};

/**
 * Move current line and column position.
 *
 * @param {String} str
 * @api private
 */

SourceMapper.prototype.move = function(str){
  var lines = str.match(/\n/g)
    , idx = str.lastIndexOf('\n');

  if (lines) this.lineno += lines.length;
  this.column = ~idx
    ? str.length - idx
    : this.column + str.length;
};

/**
 * Normalize the given `path`.
 *
 * @param {String} path
 * @return {String}
 * @api private
 */

SourceMapper.prototype.normalizePath = function(path){
  path = relative(this.dest || this.basePath, path);
  if ('\\' == sep) {
    path = path.replace(/^[a-z]:\\/i, '/')
      .replace(/\\/g, '/');
  }
  return path;
};

/**
 * Visit Literal.
 */

var literal = Compiler.prototype.visitLiteral;
SourceMapper.prototype.visitLiteral = function(lit){
  var val = literal.call(this, lit)
    , filename = this.normalizePath(lit.filename)
    , indentsRe = /^\s+/
    , lines = val.split('\n');

  // add mappings for multiline literals
  if (lines.length > 1) {
    lines.forEach(function(line, i) {
      var indents = line.match(indentsRe)
        , column = indents && indents[0]
            ? indents[0].length
            : 0;

      if (lit.css) column += 2;

      this.map.addMapping({
        original: {
          line: lit.lineno + i,
          column: column
        },
        generated: {
          line: this.lineno + i,
          column: 0
        },
        source: filename
      });
    }, this);
  }
  return val;
};

/**
 * Visit Charset.
 */

var charset = Compiler.prototype.visitCharset;
SourceMapper.prototype.visitCharset = function(node){
  this.utf8 = ('utf-8' == node.val.string.toLowerCase());
  return charset.call(this, node);
};