var babylonToEspree = require("./babylon-to-espree");
var assign         = require("lodash.assign");
var pick           = require("lodash.pickby");
var Module         = require("module");
var path           = require("path");
var parse          = require("babylon").parse;
var t              = require("babel-types");
var tt             = require("babylon").tokTypes;
var traverse       = require("babel-traverse").default;

var estraverse;
var hasPatched = false;
var eslintOptions = {};

function createModule(filename) {
  var mod = new Module(filename);
  mod.filename = filename;
  mod.paths = Module._nodeModulePaths(path.dirname(filename));
  return mod;
}

function monkeypatch() {
  if (hasPatched) return;
  hasPatched = true;

  var eslintLoc;
  try {
    // avoid importing a local copy of eslint, try to find a peer dependency
    eslintLoc = Module._resolveFilename("eslint", module.parent);
  } catch (err) {
    try {
      // avoids breaking in jest where module.parent is undefined
      eslintLoc = require.resolve("eslint");
    } catch (err) {
      throw new ReferenceError("couldn't resolve eslint");
    }
  }

  // get modules relative to what eslint will load
  var eslintMod = createModule(eslintLoc);
  var escopeLoc = Module._resolveFilename("escope", eslintMod);
  var escopeMod = createModule(escopeLoc);

  // npm 3: monkeypatch estraverse if it's in escope
  var estraverseRelative = escopeMod;
  try {
    var esrecurseLoc = Module._resolveFilename("esrecurse", eslintMod);
    estraverseRelative = createModule(esrecurseLoc);
  } catch (err) {}

  // contains all the instances of estraverse so we can modify them if necessary
  var estraverses = [];

  // monkeypatch estraverse
  estraverse = estraverseRelative.require("estraverse");
  estraverses.push(estraverse);
  assign(estraverse.VisitorKeys, t.VISITOR_KEYS);

  // monkeypatch estraverse-fb (only for eslint < 2.3.0)
  try {
    var estraverseFb = eslintMod.require("estraverse-fb");
    estraverses.push(estraverseFb);
    assign(estraverseFb.VisitorKeys, t.VISITOR_KEYS);
  } catch (err) {
      // Ignore: ESLint v2.3.0 does not have estraverse-fb
  }

  // ESLint v1.9.0 uses estraverse directly to work around https://github.com/npm/npm/issues/9663
  var estraverseOfEslint = eslintMod.require("estraverse");
  if (estraverseOfEslint !== estraverseFb) {
    estraverses.push(estraverseOfEslint);
    assign(estraverseOfEslint.VisitorKeys, t.VISITOR_KEYS);
  }

  estraverses.forEach(function (estraverse) {
    estraverse.VisitorKeys.MethodDefinition.push("decorators");
    estraverse.VisitorKeys.Property.push("decorators");
  });

  // monkeypatch escope
  var escope  = require(escopeLoc);
  var analyze = escope.analyze;
  escope.analyze = function (ast, opts) {
    opts.ecmaVersion = eslintOptions.ecmaVersion;
    opts.sourceType = eslintOptions.sourceType;
    if (eslintOptions.globalReturn !== undefined) {
      opts.nodejsScope = eslintOptions.globalReturn;
    }

    var results = analyze.call(this, ast, opts);
    return results;
  };

  // monkeypatch escope/referencer
  var referencerLoc;
  try {
    referencerLoc = Module._resolveFilename("./referencer", escopeMod);
  } catch (err) {
    throw new ReferenceError("couldn't resolve escope/referencer");
  }
  var referencerMod = createModule(referencerLoc);
  var referencer = require(referencerLoc);
  if (referencer.__esModule) {
    referencer = referencer.default;
  }

  // reference Definition
  var definitionLoc;
  try {
    definitionLoc = Module._resolveFilename("./definition", referencerMod);
  } catch (err) {
    throw new ReferenceError("couldn't resolve escope/definition");
  }
  var Definition = require(definitionLoc).Definition;

  // if there are decorators, then visit each
  function visitDecorators(node) {
    if (!node.decorators) {
      return;
    }
    for (var i = 0; i < node.decorators.length; i++) {
      if (node.decorators[i].expression) {
        this.visit(node.decorators[i]);
      }
    }
  }

  // iterate through part of t.VISITOR_KEYS
  var visitorKeysMap = pick(t.VISITOR_KEYS, function(k) {
    return t.FLIPPED_ALIAS_KEYS.Flow.concat([
      "ArrayPattern",
      "ClassDeclaration",
      "ClassExpression",
      "FunctionDeclaration",
      "FunctionExpression",
      "Identifier",
      "ObjectPattern",
      "RestElement"
    ]).indexOf(k) === -1;
  });

  var propertyTypes = {
    // loops
    callProperties: { type: "loop", values: ["value"] },
    indexers: { type: "loop", values: ["key", "value"] },
    properties: { type: "loop", values: ["value"] },
    types: { type: "loop" },
    params: { type: "loop" },
    // single property
    argument: { type: "single" },
    elementType: { type: "single" },
    qualification: { type: "single" },
    rest: { type: "single" },
    returnType: { type: "single" },
    // others
    typeAnnotation: { type: "typeAnnotation" },
    typeParameters: { type: "typeParameters" },
    id: { type: "id" }
  };

  function visitTypeAnnotation(node) {
    // get property to check (params, id, etc...)
    var visitorValues = visitorKeysMap[node.type];
    if (!visitorValues) {
      return;
    }

    // can have multiple properties
    for (var i = 0; i < visitorValues.length; i++) {
      var visitorValue = visitorValues[i];
      var propertyType = propertyTypes[visitorValue];
      var nodeProperty = node[visitorValue];
      // check if property or type is defined
      if (propertyType == null || nodeProperty == null) {
        continue;
      }
      if (propertyType.type === "loop") {
        for (var j = 0; j < nodeProperty.length; j++) {
          if (Array.isArray(propertyType.values)) {
            for (var k = 0; k < propertyType.values.length; k++) {
              checkIdentifierOrVisit.call(this, nodeProperty[j][propertyType.values[k]]);
            }
          } else {
            checkIdentifierOrVisit.call(this, nodeProperty[j]);
          }
        }
      } else if (propertyType.type === "single") {
        checkIdentifierOrVisit.call(this, nodeProperty);
      } else if (propertyType.type === "typeAnnotation") {
        visitTypeAnnotation.call(this, node.typeAnnotation);
      } else if (propertyType.type === "typeParameters") {
        for (var l = 0; l < node.typeParameters.params.length; l++) {
          checkIdentifierOrVisit.call(this, node.typeParameters.params[l]);
        }
      } else if (propertyType.type === "id") {
        if (node.id.type === "Identifier") {
          checkIdentifierOrVisit.call(this, node.id);
        } else {
          visitTypeAnnotation.call(this, node.id);
        }
      }
    }
  }

  function checkIdentifierOrVisit(node) {
    if (node.typeAnnotation) {
      visitTypeAnnotation.call(this, node.typeAnnotation);
    } else if (node.type === "Identifier") {
      this.visit(node);
    } else {
      visitTypeAnnotation.call(this, node);
    }
  }

  function nestTypeParamScope(manager, node) {
    var parentScope = manager.__currentScope;
    var scope = new escope.Scope(manager, "type-parameters", parentScope, node, false);
    manager.__nestScope(scope);
    for (var j = 0; j < node.typeParameters.params.length; j++) {
      var name = node.typeParameters.params[j];
      scope.__define(name, new Definition("TypeParameter", name, name));
    }
    scope.__define = function() {
      return parentScope.__define.apply(parentScope, arguments);
    };
    return scope;
  }

  // visit decorators that are in: ClassDeclaration / ClassExpression
  var visitClass = referencer.prototype.visitClass;
  referencer.prototype.visitClass = function(node) {
    visitDecorators.call(this, node);
    var typeParamScope;
    if (node.typeParameters) {
      typeParamScope = nestTypeParamScope(this.scopeManager, node);
    }
    // visit flow type: ClassImplements
    if (node.implements) {
      for (var i = 0; i < node.implements.length; i++) {
        checkIdentifierOrVisit.call(this, node.implements[i]);
      }
    }
    if (node.superTypeParameters) {
      for (var k = 0; k < node.superTypeParameters.params.length; k++) {
        checkIdentifierOrVisit.call(this, node.superTypeParameters.params[k]);
      }
    }
    visitClass.call(this, node);
    if (typeParamScope) {
      this.close(node);
    }
  };

  // visit decorators that are in: Property / MethodDefinition
  var visitProperty = referencer.prototype.visitProperty;
  referencer.prototype.visitProperty = function(node) {
    if (node.value && node.value.type === "TypeCastExpression") {
      visitTypeAnnotation.call(this, node.value);
    }
    visitDecorators.call(this, node);
    visitProperty.call(this, node);
  };

  // visit ClassProperty as a Property.
  referencer.prototype.ClassProperty = function(node) {
    if (node.typeAnnotation) {
      visitTypeAnnotation.call(this, node.typeAnnotation);
    }
    this.visitProperty(node);
  };

  // visit flow type in FunctionDeclaration, FunctionExpression, ArrowFunctionExpression
  var visitFunction = referencer.prototype.visitFunction;
  referencer.prototype.visitFunction = function(node) {
    var typeParamScope;
    if (node.typeParameters) {
      typeParamScope = nestTypeParamScope(this.scopeManager, node);
    }
    if (node.returnType) {
      checkIdentifierOrVisit.call(this, node.returnType);
    }
    // only visit if function parameters have types
    if (node.params) {
      for (var i = 0; i < node.params.length; i++) {
        var param = node.params[i];
        if (param.typeAnnotation) {
          checkIdentifierOrVisit.call(this, param);
        } else if (t.isAssignmentPattern(param)) {
          if (param.left.typeAnnotation) {
            checkIdentifierOrVisit.call(this, param.left);
          }
        }
      }
    }
    // set ArrayPattern/ObjectPattern visitor keys back to their original. otherwise
    // escope will traverse into them and include the identifiers within as declarations
    estraverses.forEach(function (estraverse) {
      estraverse.VisitorKeys.ObjectPattern = ["properties"];
      estraverse.VisitorKeys.ArrayPattern = ["elements"];
    });
    visitFunction.call(this, node);
    // set them back to normal...
    estraverses.forEach(function (estraverse) {
      estraverse.VisitorKeys.ObjectPattern = t.VISITOR_KEYS.ObjectPattern;
      estraverse.VisitorKeys.ArrayPattern = t.VISITOR_KEYS.ArrayPattern;
    });
    if (typeParamScope) {
      this.close(node);
    }
  };

  // visit flow type in VariableDeclaration
  var variableDeclaration = referencer.prototype.VariableDeclaration;
  referencer.prototype.VariableDeclaration = function(node) {
    if (node.declarations) {
      for (var i = 0; i < node.declarations.length; i++) {
        var id = node.declarations[i].id;
        var typeAnnotation = id.typeAnnotation;
        if (typeAnnotation) {
          checkIdentifierOrVisit.call(this, typeAnnotation);
        }
      }
    }
    variableDeclaration.call(this, node);
  };

  function createScopeVariable (node, name) {
    this.currentScope().variableScope.__define(name,
      new Definition(
        "Variable",
        name,
        node,
        null,
        null,
        null
      )
    );
  }

  referencer.prototype.TypeAlias = function(node) {
    createScopeVariable.call(this, node, node.id);
    var typeParamScope;
    if (node.typeParameters) {
      typeParamScope = nestTypeParamScope(this.scopeManager, node);
    }
    if (node.right) {
      visitTypeAnnotation.call(this, node.right);
    }
    if (typeParamScope) {
      this.close(node);
    }
  };

  referencer.prototype.DeclareModule =
  referencer.prototype.DeclareFunction =
  referencer.prototype.DeclareVariable =
  referencer.prototype.DeclareClass = function(node) {
    if (node.id) {
      createScopeVariable.call(this, node, node.id);
    }

    var typeParamScope;
    if (node.typeParameters) {
      typeParamScope = nestTypeParamScope(this.scopeManager, node);
    }
    if (typeParamScope) {
      this.close(node);
    }
  };
}

exports.parse = function (code, options) {
  options = options || {};
  eslintOptions.ecmaVersion = options.ecmaVersion = options.ecmaVersion || 6;
  eslintOptions.sourceType = options.sourceType = options.sourceType || "module";
  eslintOptions.allowImportExportEverywhere = options.allowImportExportEverywhere = options.allowImportExportEverywhere || false;
  if (options.sourceType === "module") {
    eslintOptions.globalReturn = false;
  } else {
    delete eslintOptions.globalReturn;
  }

  try {
    monkeypatch();
  } catch (err) {
    console.error(err.stack);
    process.exit(1);
  }

  return exports.parseNoPatch(code, options);
}

exports.parseNoPatch = function (code, options) {
  var opts = {
    sourceType: options.sourceType,
    allowImportExportEverywhere: options.allowImportExportEverywhere, // consistent with espree
    allowReturnOutsideFunction: true,
    allowSuperOutsideMethod: true,
    plugins: [
        "flow",
        "jsx",
        "asyncFunctions",
        "asyncGenerators",
        "classConstructorCall",
        "classProperties",
        "decorators",
        "doExpressions",
        "exponentiationOperator",
        "exportExtensions",
        "functionBind",
        "functionSent",
        "objectRestSpread",
        "trailingFunctionCommas"
    ]
  };

  var ast;
  try {
    ast = parse(code, opts);
  } catch (err) {
    if (err instanceof SyntaxError) {
      err.lineNumber = err.loc.line;
      err.column = err.loc.column + 1;

      // remove trailing "(LINE:COLUMN)" acorn message and add in esprima syntax error message start
      err.message = "Line " + err.lineNumber + ": " + err.message.replace(/ \((\d+):(\d+)\)$/, "");
    }

    throw err;
  }

  // remove EOF token, eslint doesn't use this for anything and it interferes with some rules
  // see https://github.com/babel/babel-eslint/issues/2 for more info
  // todo: find a more elegant way to do this
  ast.tokens.pop();

  // convert tokens
  ast.tokens = babylonToEspree.toTokens(ast.tokens, tt, code);

  // add comments
  babylonToEspree.convertComments(ast.comments);

  // transform esprima and acorn divergent nodes
  babylonToEspree.toAST(ast, traverse, code);

  // ast.program.tokens = ast.tokens;
  // ast.program.comments = ast.comments;
  // ast = ast.program;

  // remove File
  ast.type = "Program";
  ast.sourceType = ast.program.sourceType;
  ast.directives = ast.program.directives;
  ast.body = ast.program.body;
  delete ast.program;
  delete ast._paths;

  babylonToEspree.attachComments(ast, ast.comments, ast.tokens);

  return ast;
}
