require("./patch");

var estraverse = require("estraverse");
var traverse   = require("./traverse");
var acorn      = require("acorn-6to5");
var path       = require("path");
var util       = require("util");
var fs         = require("fs");
var t          = require("./types");
var _          = require("lodash");

exports.inherits = util.inherits;

exports.canCompile = function (filename, altExts) {
  var exts = altExts || [".js", ".jsx", ".es6"];
  var ext = path.extname(filename);
  return _.contains(exts, ext);
};

exports.resolve = function (loc) {
  try {
    return require.resolve(loc);
  } catch (err) {
    return null;
  }
};

exports.list = function (val) {
  return val ? val.split(",") : [];
};

exports.getUid = function (parent, file) {
  var node;

  if (t.isAssignmentExpression(parent)) {
    node = parent.left;
  } else if (t.isVariableDeclarator(parent)) {
    node = parent.id;
  }

  var id = "ref";

  if (t.isIdentifier(node)) id = node.name;

  return t.identifier(file.generateUid(id));
};

exports.isAbsolute = function (loc) {
  if (!loc) return false;
  if (loc[0] === "/") return true; // unix
  if (loc[1] === ":" && loc[2] === "\\") return true; // windows
  return false;
};

exports.sourceMapToComment = function (map) {
  var json = JSON.stringify(map);
  var base64 = new Buffer(json).toString("base64");
  return "//# sourceMappingURL=data:application/json;base64," + base64;
};

exports.pushMutatorMap = function (mutatorMap, key, kind, method) {
  var alias;

  if (t.isIdentifier(key)) {
    alias = key.name;
    if (method.computed) alias = "computed:" + alias;
  } else if (t.isLiteral(key)) {
    alias = String(key.value);
  } else {
    alias = JSON.stringify(traverse.removeProperties(_.cloneDeep(key)));
  }

  var map;
  if (_.has(mutatorMap, alias)) {
    map = mutatorMap[alias];
  } else {
    map = {};
  }
  mutatorMap[alias] = map;

  map._key = key;
  if (method.computed) {
    map._computed = true;
  }

  map[kind] = method;
};

exports.buildDefineProperties = function (mutatorMap) {
  var objExpr = t.objectExpression([]);

  _.each(mutatorMap, function (map) {
    var mapNode = t.objectExpression([]);

    var propNode = t.property("init", map._key, mapNode, map._computed);

    _.each(map, function (node, key) {
      if (key[0] === "_") return;

      node = _.clone(node);
      if (t.isMethodDefinition(node)) node = node.value;
      mapNode.properties.push(t.property("init", t.identifier(key), node));
    });

    objExpr.properties.push(propNode);
  });

  return objExpr;
};

exports.template = function (name, nodes, keepExpression) {
  var template = exports.templates[name];
  if (!template) throw new ReferenceError("unknown template " + name);

  if (nodes === true) {
    keepExpression = true;
    nodes = null;
  }

  template = _.cloneDeep(template);

  var inherits = false;
  if (nodes) {
    inherits = nodes.inherits;
    delete nodes.inherits;

    if (!_.isEmpty(nodes)) {
      traverse(template, function (node) {
        if (t.isIdentifier(node) && _.has(nodes, node.name)) {
          var newNode = nodes[node.name];
          if (_.isString(newNode)) {
            node.name = newNode;
          } else {
            return newNode;
          }
        }
      });
    }
  }

  var node = template.body[0];

  if (!keepExpression && t.isExpressionStatement(node)) {
    node = node.expression;

    if (t.isParenthesizedExpression(node)) node = node.expression;
  }

  if (inherits) {
    node = t.inherits(node, inherits);
  }

  return node;
};

exports.codeFrame = function (lines, lineNumber, colNumber) {
  colNumber = Math.max(colNumber, 0);

  lines = lines.split("\n");

  var start = Math.max(lineNumber - 3, 0);
  var end   = Math.min(lines.length, lineNumber + 3);
  var width = (end + "").length;

  if (!lineNumber && !colNumber) {
    start = 0;
    end = lines.length;
  }

  return "\n" + lines.slice(start, end).map(function (line, i) {
    var curr = i + start + 1;

    var gutter = curr === lineNumber ? "> " : "  ";

    var sep = curr + exports.repeat(width + 1);
    gutter += sep + "| ";

    var str = gutter + line;

    if (colNumber && curr === lineNumber) {
      str += "\n";
      str += exports.repeat(gutter.length - 2);
      str += "|" + exports.repeat(colNumber) + "^";
    }

    return str;
  }).join("\n");
};

exports.repeat = function (width, cha) {
  cha = cha || " ";
  return new Array(width + 1).join(cha);
};

exports.parse = function (opts, code, callback) {
  try {
    var comments = [];
    var tokens   = [];

    var ast = acorn.parse(code, {
      allowReturnOutsideFunction: true,
      preserveParens:             true,
      ecmaVersion:                Infinity,
      strictMode:                 true,
      onComment:                  comments,
      locations:                  true,
      onToken:                    tokens,
      ranges:                     true
    });

    estraverse.attachComments(ast, comments, tokens);

    ast = t.file(ast, comments, tokens);

    traverse(ast, function (node, parent) {
      node._parent = parent;
    });

    if (callback) {
      return callback(ast);
    } else {
      return ast;
    }
  } catch (err) {
    if (!err._6to5) {
      err._6to5 = true;
      var message = opts.filename + ": " + err.message;

      var loc = err.loc;
      if (loc) {
        var frame = exports.codeFrame(code, loc.line, loc.column);
        message += frame;
      }

      if (err.stack) err.stack = err.stack.replace(err.message, message);
      err.message = message;
    }

    throw err;
  }
};

exports.parseNoProperties = function (loc, code) {
  var ast = exports.parse({ filename: loc }, code).program;
  return traverse.removeProperties(ast);
};

var loadTemplates = function () {
  var templates = {};

  var templatesLoc = __dirname + "/templates";
  if (!fs.existsSync(templatesLoc)) {
    throw new Error("no templates directory - this is most likely the " +
                    "result of a broken `npm publish`. Please report to " +
                    "https://githut.com/6to5/6to5/issues");
  }

  _.each(fs.readdirSync(templatesLoc), function (name) {
    if (name[0] === ".") return;

    var key  = path.basename(name, path.extname(name));
    var loc  = templatesLoc + "/" + name;
    var code = fs.readFileSync(loc, "utf8");

    templates[key] = exports.parseNoProperties(loc, code);
  });

  return templates;
};

try {
  exports.templates = require("../../templates.json");
} catch (err) {
  if (err.code !== "MODULE_NOT_FOUND") throw err;

  Object.defineProperty(exports, "templates", {
    get: function () {
      return exports.templates = loadTemplates();
    }
  });
}