module.exports = function (fork) {
    var types = fork.use(require("../lib/types"));
    var Type = types.Type;
    var def = Type.def;
    var or = Type.or;
    var shared = fork.use(require("../lib/shared"));
    var defaults = shared.defaults;
    var geq = shared.geq;

    // Abstract supertype of all syntactic entities that are allowed to have a
    // .loc field.
    def("Printable")
        .field("loc", or(
            def("SourceLocation"),
            null
        ), defaults["null"], true);

    def("Node")
        .bases("Printable")
        .field("type", String)
        .field("comments", or(
            [def("Comment")],
            null
        ), defaults["null"], true);

    def("SourceLocation")
        .build("start", "end", "source")
        .field("start", def("Position"))
        .field("end", def("Position"))
        .field("source", or(String, null), defaults["null"]);

    def("Position")
        .build("line", "column")
        .field("line", geq(1))
        .field("column", geq(0));

    def("File")
        .bases("Node")
        .build("program", "name")
        .field("program", def("Program"))
        .field("name", or(String, null), defaults["null"]);

    def("Program")
        .bases("Node")
        .build("body")
        .field("body", [def("Statement")]);

    def("Function")
        .bases("Node")
        .field("id", or(def("Identifier"), null), defaults["null"])
        .field("params", [def("Pattern")])
        .field("body", def("BlockStatement"));

    def("Statement").bases("Node");

// The empty .build() here means that an EmptyStatement can be constructed
// (i.e. it's not abstract) but that it needs no arguments.
    def("EmptyStatement").bases("Statement").build();

    def("BlockStatement")
        .bases("Statement")
        .build("body")
        .field("body", [def("Statement")]);

    // TODO Figure out how to silently coerce Expressions to
    // ExpressionStatements where a Statement was expected.
    def("ExpressionStatement")
        .bases("Statement")
        .build("expression")
        .field("expression", def("Expression"));

    def("IfStatement")
        .bases("Statement")
        .build("test", "consequent", "alternate")
        .field("test", def("Expression"))
        .field("consequent", def("Statement"))
        .field("alternate", or(def("Statement"), null), defaults["null"]);

    def("LabeledStatement")
        .bases("Statement")
        .build("label", "body")
        .field("label", def("Identifier"))
        .field("body", def("Statement"));

    def("BreakStatement")
        .bases("Statement")
        .build("label")
        .field("label", or(def("Identifier"), null), defaults["null"]);

    def("ContinueStatement")
        .bases("Statement")
        .build("label")
        .field("label", or(def("Identifier"), null), defaults["null"]);

    def("WithStatement")
        .bases("Statement")
        .build("object", "body")
        .field("object", def("Expression"))
        .field("body", def("Statement"));

    def("SwitchStatement")
        .bases("Statement")
        .build("discriminant", "cases", "lexical")
        .field("discriminant", def("Expression"))
        .field("cases", [def("SwitchCase")])
        .field("lexical", Boolean, defaults["false"]);

    def("ReturnStatement")
        .bases("Statement")
        .build("argument")
        .field("argument", or(def("Expression"), null));

    def("ThrowStatement")
        .bases("Statement")
        .build("argument")
        .field("argument", def("Expression"));

    def("TryStatement")
        .bases("Statement")
        .build("block", "handler", "finalizer")
        .field("block", def("BlockStatement"))
        .field("handler", or(def("CatchClause"), null), function () {
            return this.handlers && this.handlers[0] || null;
        })
        .field("handlers", [def("CatchClause")], function () {
            return this.handler ? [this.handler] : [];
        }, true) // Indicates this field is hidden from eachField iteration.
        .field("guardedHandlers", [def("CatchClause")], defaults.emptyArray)
        .field("finalizer", or(def("BlockStatement"), null), defaults["null"]);

    def("CatchClause")
        .bases("Node")
        .build("param", "guard", "body")
        // https://github.com/tc39/proposal-optional-catch-binding
        .field("param", or(def("Pattern"), null), defaults["null"])
        .field("guard", or(def("Expression"), null), defaults["null"])
        .field("body", def("BlockStatement"));

    def("WhileStatement")
        .bases("Statement")
        .build("test", "body")
        .field("test", def("Expression"))
        .field("body", def("Statement"));

    def("DoWhileStatement")
        .bases("Statement")
        .build("body", "test")
        .field("body", def("Statement"))
        .field("test", def("Expression"));

    def("ForStatement")
        .bases("Statement")
        .build("init", "test", "update", "body")
        .field("init", or(
            def("VariableDeclaration"),
            def("Expression"),
            null))
        .field("test", or(def("Expression"), null))
        .field("update", or(def("Expression"), null))
        .field("body", def("Statement"));

    def("ForInStatement")
        .bases("Statement")
        .build("left", "right", "body")
        .field("left", or(
            def("VariableDeclaration"),
            def("Expression")))
        .field("right", def("Expression"))
        .field("body", def("Statement"));

    def("DebuggerStatement").bases("Statement").build();

    def("Declaration").bases("Statement");

    def("FunctionDeclaration")
        .bases("Function", "Declaration")
        .build("id", "params", "body")
        .field("id", def("Identifier"));

    def("FunctionExpression")
        .bases("Function", "Expression")
        .build("id", "params", "body");

    def("VariableDeclaration")
        .bases("Declaration")
        .build("kind", "declarations")
        .field("kind", or("var", "let", "const"))
        .field("declarations", [def("VariableDeclarator")]);

    def("VariableDeclarator")
        .bases("Node")
        .build("id", "init")
        .field("id", def("Pattern"))
        .field("init", or(def("Expression"), null));

    // TODO Are all Expressions really Patterns?
    def("Expression").bases("Node", "Pattern");

    def("ThisExpression").bases("Expression").build();

    def("ArrayExpression")
        .bases("Expression")
        .build("elements")
        .field("elements", [or(def("Expression"), null)]);

    def("ObjectExpression")
        .bases("Expression")
        .build("properties")
        .field("properties", [def("Property")]);

    // TODO Not in the Mozilla Parser API, but used by Esprima.
    def("Property")
        .bases("Node") // Want to be able to visit Property Nodes.
        .build("kind", "key", "value")
        .field("kind", or("init", "get", "set"))
        .field("key", or(def("Literal"), def("Identifier")))
        .field("value", def("Expression"));

    def("SequenceExpression")
        .bases("Expression")
        .build("expressions")
        .field("expressions", [def("Expression")]);

    var UnaryOperator = or(
        "-", "+", "!", "~",
        "typeof", "void", "delete");

    def("UnaryExpression")
        .bases("Expression")
        .build("operator", "argument", "prefix")
        .field("operator", UnaryOperator)
        .field("argument", def("Expression"))
        // Esprima doesn't bother with this field, presumably because it's
        // always true for unary operators.
        .field("prefix", Boolean, defaults["true"]);

    var BinaryOperator = or(
        "==", "!=", "===", "!==",
        "<", "<=", ">", ">=",
        "<<", ">>", ">>>",
        "+", "-", "*", "/", "%", "**",
        "&", // TODO Missing from the Parser API.
        "|", "^", "in",
        "instanceof", "..");

    def("BinaryExpression")
        .bases("Expression")
        .build("operator", "left", "right")
        .field("operator", BinaryOperator)
        .field("left", def("Expression"))
        .field("right", def("Expression"));

    var AssignmentOperator = or(
        "=", "+=", "-=", "*=", "/=", "%=",
        "<<=", ">>=", ">>>=",
        "|=", "^=", "&=");

    def("AssignmentExpression")
        .bases("Expression")
        .build("operator", "left", "right")
        .field("operator", AssignmentOperator)
        .field("left", def("Pattern"))
        .field("right", def("Expression"));

    var UpdateOperator = or("++", "--");

    def("UpdateExpression")
        .bases("Expression")
        .build("operator", "argument", "prefix")
        .field("operator", UpdateOperator)
        .field("argument", def("Expression"))
        .field("prefix", Boolean);

    var LogicalOperator = or("||", "&&");

    def("LogicalExpression")
        .bases("Expression")
        .build("operator", "left", "right")
        .field("operator", LogicalOperator)
        .field("left", def("Expression"))
        .field("right", def("Expression"));

    def("ConditionalExpression")
        .bases("Expression")
        .build("test", "consequent", "alternate")
        .field("test", def("Expression"))
        .field("consequent", def("Expression"))
        .field("alternate", def("Expression"));

    def("NewExpression")
        .bases("Expression")
        .build("callee", "arguments")
        .field("callee", def("Expression"))
        // The Mozilla Parser API gives this type as [or(def("Expression"),
        // null)], but null values don't really make sense at the call site.
        // TODO Report this nonsense.
        .field("arguments", [def("Expression")]);

    def("CallExpression")
        .bases("Expression")
        .build("callee", "arguments")
        .field("callee", def("Expression"))
        // See comment for NewExpression above.
        .field("arguments", [def("Expression")]);

    def("MemberExpression")
        .bases("Expression")
        .build("object", "property", "computed")
        .field("object", def("Expression"))
        .field("property", or(def("Identifier"), def("Expression")))
        .field("computed", Boolean, function () {
            var type = this.property.type;
            if (type === 'Literal' ||
                type === 'MemberExpression' ||
                type === 'BinaryExpression') {
                return true;
            }
            return false;
        });

    def("Pattern").bases("Node");

    def("SwitchCase")
        .bases("Node")
        .build("test", "consequent")
        .field("test", or(def("Expression"), null))
        .field("consequent", [def("Statement")]);

    def("Identifier")
        // But aren't Expressions and Patterns already Nodes? TODO Report this.
        .bases("Node", "Expression", "Pattern")
        .build("name")
        .field("name", String)
        .field("optional", Boolean, defaults["false"]);

    def("Literal")
        // But aren't Expressions already Nodes? TODO Report this.
        .bases("Node", "Expression")
        .build("value")
        .field("value", or(String, Boolean, null, Number, RegExp))
        .field("regex", or({
            pattern: String,
            flags: String
        }, null), function () {
            if (this.value instanceof RegExp) {
                var flags = "";

                if (this.value.ignoreCase) flags += "i";
                if (this.value.multiline) flags += "m";
                if (this.value.global) flags += "g";

                return {
                    pattern: this.value.source,
                    flags: flags
                };
            }

            return null;
        });

    // Abstract (non-buildable) comment supertype. Not a Node.
    def("Comment")
        .bases("Printable")
        .field("value", String)
        // A .leading comment comes before the node, whereas a .trailing
        // comment comes after it. These two fields should not both be true,
        // but they might both be false when the comment falls inside a node
        // and the node has no children for the comment to lead or trail,
        // e.g. { /*dangling*/ }.
        .field("leading", Boolean, defaults["true"])
        .field("trailing", Boolean, defaults["false"]);
};
