/**
 * Copyright 2013 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*global exports:true*/

/**
 * State represents the given parser state. It has a local and global parts.
 * Global contains parser position, source, etc. Local contains scope based
 * properties, like current class name. State should contain all the info
 * required for transformation. It's the only mandatory object that is being
 * passed to every function in transform chain.
 *
 * @param  {String} source
 * @param  {Object} transformOptions
 * @return {Object}
 */
function createState(source, transformOptions) {
  return {
    /**
     * Name of the super class variable
     * @type {String}
     */
    superVar: '',
    /**
     * Name of the enclosing class scope
     * @type {String}
     */
    scopeName: '',
    /**
     * Global state (not affected by updateState)
     * @type {Object}
     */
    g: {
      /**
       * A set of general options that transformations can consider while doing
       * a transformation:
       *
       * - minify
       *   Specifies that transformation steps should do their best to minify
       *   the output source when possible. This is useful for places where
       *   minification optimizations are possible with higher-level context
       *   info than what jsxmin can provide.
       *
       *   For example, the ES6 class transform will minify munged private
       *   variables if this flag is set.
       */
      opts: transformOptions,
      /**
       * Current position in the source code
       * @type {Number}
       */
      position: 0,
      /**
       * Buffer containing the result
       * @type {String}
       */
      buffer: '',
      /**
       * Indentation offset (only negative offset is supported now)
       * @type {Number}
       */
      indentBy: 0,
      /**
       * Source that is being transformed
       * @type {String}
       */
      source: source,

      /**
       * Cached parsed docblock (see getDocblock)
       * @type {object}
       */
      docblock: null,

      /**
       * Whether the thing was used
       * @type {Boolean}
       */
      tagNamespaceUsed: false,

      /**
       * If using bolt xjs transformation
       * @type {Boolean}
       */
      isBolt: undefined,

      /**
       * Whether to record source map (expensive) or not
       * @type {SourceMapGenerator|null}
       */
      sourceMap: null,

      /**
       * Filename of the file being processed. Will be returned as a source
       * attribute in the source map
       */
      sourceMapFilename: 'source.js',

      /**
       * Only when source map is used: last line in the source for which
       * source map was generated
       * @type {Number}
       */
      sourceLine: 1,

      /**
       * Only when source map is used: last line in the buffer for which
       * source map was generated
       * @type {Number}
       */
      bufferLine: 1,

      /**
       * The top-level Program AST for the original file.
       */
      originalProgramAST: null,

      sourceColumn: 0,
      bufferColumn: 0
    }
  };
}

/**
 * Updates a copy of a given state with "update" and returns an updated state.
 *
 * @param  {Object} state
 * @param  {Object} update
 * @return {Object}
 */
function updateState(state, update) {
  return {
    g: state.g,
    superVar: update.superVar || state.superVar,
    scopeName: update.scopeName || state.scopeName
  };
}

/**
 * Given a state fill the resulting buffer from the original source up to
 * the end
 * @param  {Number} end
 * @param  {Object} state
 * @param {Function?} contentTransformer Optional callback to transform newly
 * added content.
 */
function catchup(end, state, contentTransformer) {
  if (end < state.g.position) {
    // cannot move backwards
    return;
  }
  var source = state.g.source.substring(state.g.position, end);
  var transformed = updateIndent(source, state);
  if (state.g.sourceMap && transformed) {
    // record where we are
    state.g.sourceMap.addMapping({
      generated: { line: state.g.bufferLine, column: state.g.bufferColumn },
      original: { line: state.g.sourceLine, column: state.g.sourceColumn },
      source: state.g.sourceMapFilename
    });

    // record line breaks in transformed source
    var sourceLines = source.split('\n');
    var transformedLines = transformed.split('\n');
    // Add line break mappings between last known mapping and the end of the
    // added piece. So for the code piece
    //  (foo, bar);
    // > var x = 2;
    // > var b = 3;
    //   var c =
    // only add lines marked with ">": 2, 3.
    for (var i = 1; i < sourceLines.length - 1; i++) {
      state.g.sourceMap.addMapping({
        generated: { line: state.g.bufferLine, column: 0 },
        original: { line: state.g.sourceLine, column: 0 },
        source: state.g.sourceMapFilename
      });
      state.g.sourceLine++;
      state.g.bufferLine++;
    }
    // offset for the last piece
    if (sourceLines.length > 1) {
      state.g.sourceLine++;
      state.g.bufferLine++;
      state.g.sourceColumn = 0;
      state.g.bufferColumn = 0;
    }
    state.g.sourceColumn += sourceLines[sourceLines.length - 1].length;
    state.g.bufferColumn +=
      transformedLines[transformedLines.length - 1].length;
  }
  state.g.buffer +=
    contentTransformer ? contentTransformer(transformed) : transformed;
  state.g.position = end;
}

/**
 * Applies `catchup` but passing in a function that removes any non-whitespace
 * characters.
 */
var re = /(\S)/g;
function stripNonWhite(value) {
  return value.replace(re, function() {
    return '';
  });
}
/**
 * Catches up as `catchup` but turns each non-white character into a space.
 */
function catchupWhiteSpace(end, state) {
  catchup(end, state, stripNonWhite);
}

/**
 * Same as catchup but does not touch the buffer
 * @param  {Number} end
 * @param  {Object} state
 */
function move(end, state) {
  // move the internal cursors
  if (state.g.sourceMap) {
    if (end < state.g.position) {
      state.g.position = 0;
      state.g.sourceLine = 1;
      state.g.sourceColumn = 0;
    }

    var source = state.g.source.substring(state.g.position, end);
    var sourceLines = source.split('\n');
    if (sourceLines.length > 1) {
      state.g.sourceLine += sourceLines.length - 1;
      state.g.sourceColumn = 0;
    }
    state.g.sourceColumn += sourceLines[sourceLines.length - 1].length;
  }
  state.g.position = end;
}

/**
 * Appends a string of text to the buffer
 * @param  {String} string
 * @param  {Object} state
 */
function append(string, state) {
  if (state.g.sourceMap && string) {
    state.g.sourceMap.addMapping({
      generated: { line: state.g.bufferLine, column: state.g.bufferColumn },
      original: { line: state.g.sourceLine, column: state.g.sourceColumn },
      source: state.g.sourceMapFilename
    });
    var transformedLines = string.split('\n');
    if (transformedLines.length > 1) {
      state.g.bufferLine += transformedLines.length - 1;
      state.g.bufferColumn = 0;
    }
    state.g.bufferColumn +=
      transformedLines[transformedLines.length - 1].length;
  }
  state.g.buffer += string;
}

/**
 * Update indent using state.indentBy property. Indent is measured in
 * double spaces. Updates a single line only.
 *
 * @param  {String} str
 * @param  {Object} state
 * @return {String}
 */
function updateIndent(str, state) {
  for (var i = 0; i < -state.g.indentBy; i++) {
    str = str.replace(/(^|\n)( {2}|\t)/g, '$1');
  }
  return str;
}

/**
 * Calculates indent from the beginning of the line until "start" or the first
 * character before start.
 * @example
 *   "  foo.bar()"
 *         ^
 *       start
 *   indent will be 2
 *
 * @param  {Number} start
 * @param  {Object} state
 * @return {Number}
 */
function indentBefore(start, state) {
  var end = start;
  start = start - 1;

  while (start > 0 && state.g.source[start] != '\n') {
    if (!state.g.source[start].match(/[ \t]/)) {
      end = start;
    }
    start--;
  }
  return state.g.source.substring(start + 1, end);
}

function getDocblock(state) {
  if (!state.g.docblock) {
    var docblock = require('./docblock');
    state.g.docblock =
      docblock.parseAsObject(docblock.extract(state.g.source));
  }
  return state.g.docblock;
}

exports.catchup = catchup;
exports.catchupWhiteSpace = catchupWhiteSpace;
exports.append = append;
exports.move = move;
exports.updateIndent = updateIndent;
exports.indentBefore = indentBefore;
exports.updateState = updateState;
exports.createState = createState;
exports.getDocblock = getDocblock;