# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2019 Louis-Vincent Boudreault <lv.boudreault95@gmail.com>
#
# 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.

# This module is only used to generate `functional_types.nit`
module functional_gen

# Generates of an array of formal type as strings.
# The size of the array equals the arity of the class.
fun gen_generics(nargs: Int): Array[String]
do
        var args = new Array[String]
        for i in [0..nargs[ do
                args.push("A" + i.to_s)
        end
        return args
end

class RoutineTemplate
        var classkind: String
        var classname: String
        var nb_generics: Int
        var supers: Array[String]
        var has_return: Bool
        var is_redef = false
        var annotation = "is abstract"

        fun callparams: Array[String]
        do
                var generics = gen_generics(nb_generics)
                var params = new Array[String]
                for g in generics do
                        if is_redef then
                                params.push(g.to_lower)
                        else
                                params.push(g.to_lower + ": " + g)
                        end
                end
                return params
        end

        fun classparams: Array[String]
        do
                var res = gen_generics(nb_generics)
                if has_return then res.add("RESULT")
                return res
        end

        redef fun to_s
        do
                var signature = ""
                var callparams = self.callparams
                var classparams = self.classparams

                if callparams.length > 0 then signature = "({callparams.join(",")})"
                if has_return then signature += ": RESULT"
                var classdecl = "{classkind} {classname}"
                if classparams.length > 0 then classdecl += "[{classparams.join(",")}]"
                var superdecls = new Array[String]
                for s in supers do superdecls.add("\tsuper {s}")

                var classdef = new Array[String]
                var redefkw = ""
                if is_redef then redefkw = "redef "
                classdef.add("{classdecl}")
                classdef.add("{superdecls.join("\n")}")
                classdef.add("\t{redefkw}fun call{signature} {annotation}")
                classdef.add("end")
                return classdef.join("\n")
        end
end

# Writes all functional types
fun generate_functypes(n: Int, writer: Writer)
do
        writer.write("""
# This file is part of NIT ( http://www.nitlanguage.org ).
#
# 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.

# This module provides functional type to represents various function forms.
# Function types can hold up to 20 arguments. The type `Fun` is for function
# (input and output) and `Proc` is for procedure (input but no output).
# This file is automatically generated, do not edit it manually.
module functional_types

interface Routine
end
interface Fun
        super Routine
end
interface Proc
        super Routine
end
""")
        var templates = new Array[String]
        var templates2 = new Array[String]
        for i in [0..n[ do
                var t1 = new RoutineTemplate("interface", "Fun{i}", i, ["Fun"], true)
                var t2 = new RoutineTemplate("interface", "Proc{i}", i, ["Proc"], false)
                templates.push(t1.to_s)
                templates.push(t2.to_s)

                # We want routine ref to be at the end of the file
                var t3 = new RoutineTemplate("universal", "FunRef{i}", i, ["Fun{i}{t1.classparams}"], true)
                var procsuper = "Proc{i}"
                if i > 0 then procsuper = "Proc{i}{t2.classparams}"
                var t4 = new RoutineTemplate("universal", "ProcRef{i}", i, [procsuper], false)
                t3.annotation = "is intern"
                t3.is_redef = true
                t4.annotation = "is intern"
                t4.is_redef = true
                templates2.push(t3.to_s)
                templates2.push(t4.to_s)
        end
        templates.add_all(templates2)
        templates.add(
"""
universal RoutineRef
end
""")
        writer.write(templates.join("\n"))
end

var fw = new FileWriter.open("functional_types.nit")
generate_functypes(20, fw)