/*
MIT License
Copyright (c) 2017 Boris Barboris
*/

module daii;

import std.experimental.allocator.mallocator: Mallocator;

static import daii.unique;
static import daii.refcounted;
static import daii.closure;
import daii.utils;

template AllocationContext(Allocator = Mallocator, bool Atomic = true)
    if (isAllocator!Allocator)
{
    alias Unique = daii.unique.AllocationContext!(Allocator, Atomic).Unique;

    alias RefCounted = daii.refcounted.AllocationContext!(Allocator, Atomic).RefCounted;

    alias Delegate = daii.closure.AllocationContext!(Allocator, Atomic).Delegate;

    alias autodlg = daii.closure.AllocationContext!(Allocator, Atomic).autodlg;
}

// main for unittests to run
void main(){}



/*    Examples     */
unittest
{
    // Create a shortcut to allocation context:
    alias MallocCtx = AllocationContext!(Mallocator, true);
    // MyCtx will contain primitives, that use static malloc and atomic operations
    // where applicable. Currently, Atomic option is only used in reference counter
    // decrement\increment of RefCounted struct.

    // Create some aliases up to your taste
    alias Unique = MallocCtx.Unique;
    alias RefCounted = MallocCtx.RefCounted;
    alias Delegate = MallocCtx.Delegate;
    alias autodlg = MallocCtx.autodlg;

    // Unique
    {
        static int ades = 0;
        class A { ~this() { ades++; } }
        static int bdes = 0;
        class B: A
        {
            this(int x_init) { x = x_init; }
            int x;
            ~this(){ bdes++; }
        }
        {
            Unique!A aq = Unique!A.make();
            {
                Unique!A bq = Unique!B.make(5);  // supports upcasting
                // Unique is not a proxy for the resource,
                // access underlying object by .v property.
                B val = cast(B) bq.v;
                assert(val.x == 5);
                val.x = 4;
                assert(val.x == 4);
            }   // bq destroyed
            assert(bdes == 1);  // instance of B was destroyed
            assert(ades == 1);  // A's destructor called as well obviously
            Unique!A cq = aq.move;  // use move to transfer ownership
            assert(!aq.valid);  // aq no longer holds value
            void consume(Unique!A ptr)
            {
                assert(ptr.valid);
            }   // ptr destroyed
            consume(cq.move);   // use move to transfer ownership
            assert(ades == 2);  // consume destroyed the resource held in cq
            assert(bdes == 1);
            assert(!cq.valid);
        }
    }
    {
        auto uptr = Unique!int.make(5);
        // you can convert uniqueptr to refcounted, but not vice versa
        RefCounted!int rcptr = uptr.toRefCounted();
        assert(!uptr.valid);
        assert(rcptr.v == 5);
    }

    // RefCounted
    {
        static int adec = 0;
        class C { ~this() { adec++; } }
        static int bdec = 0;
        class D: C { ~this() { bdec++; }}
        {
            RefCounted!C ag = RefCounted!C.make();
            {
                RefCounted!C aq = ag;   // copy constructor is not disabled
                assert(aq.valid && ag.valid);
                {
                    RefCounted!C bq = RefCounted!D.make();  // upcast OK
                }   // bq destroyed
                assert(adec == 1);
                assert(bdec == 1);
            }   // aq out of scope, but it's resource is not destroyed
            // ag still holds the valid pointer
            assert(ag.valid);
            assert(adec == 1);
            assert(bdec == 1);
        } // ag is the last owner, destructor called on A's instance
        assert(adec == 2);
        assert(bdec == 1);
    }

    // Delegate
    {
        // case1
        {
            int sum = 0;
            int[] arr = [3, 5, 1, 9, 4];
            // Delegate!(T1, T2, T3 ...) is a struct, that overloads opCall with signature
            // T1 opCall(T2 p1, T3 p2 ...).First template parameter is the return type.
            // Use `void` if it's a procedure.
            void map(int[] arr, Delegate!(void, int) dlg)
            {
                for (int i = 0; i < arr.length; i++)
                    dlg(arr[i]);
            }
            // autodlg function deduces delegate type from it's arguments.
            // It's first argument is allocator instance. Since we use allocation
            // context with static allocator (Mallocator.instance), we don't
            // need to pass it here.
            // It's second argument is function pointer.
            // The rest arguments are captured variables. Here, `sum` is captured
            // by pointer.
            // `sum` is bound to `s` function parameter. `x` is taken from
            // the opCall of resulting Delegate.
            // You are not limited to one captured parameter.
            auto dlg = autodlg((int x, int* s) { *s += x; }, &sum);
            map(arr, dlg);
            assert(sum == 22);
        }
        // case2
        {
            static int counter = 0;
            // This call to autodlg constructs eponymous closure, that holds
            // one int field. `int` type is deduced from `0`, not from `ref int ctr`.
            // Function gets the reference `ref int ctr` to said
            // int field of the closure.
            Delegate!(void) dlg = autodlg((ref int ctr) { ctr++; counter = ctr; }, 0);
            dlg();
            dlg();
            assert(counter == 2);
            // Internally dlg holds a reference-counted instance of abstract
            // class Closure. Body of this eponymous derived class contains the
            // int field.
            void consumeDlg(Delegate!(void) d) { d(); }    // the same closure
            consumeDlg(dlg);
            assert(counter == 3);
            // OpEquals is overloaded to compare closure identity
            auto dlg2 = dlg;
            assert(dlg2 == dlg);
        }
        // case3
        {
            import std.algorithm.comparison: equal;
            import std.container.array: Array;

            static string global_str;
            class EventGenerator
            {
                Array!(Delegate!(void, string)) handlers;
                void raise(string s)
                {
                    foreach (dlg; handlers)
                        dlg(s);
                }
            }
            class EventReciever
            {
                string mystr;
                this(string custom_str) { mystr = custom_str; }
                void recieve(string evt)
                {
                    global_str ~= mystr;
                    global_str ~= evt;
                }
                ~this()
                {
                    global_str ~= "D";
                }
            }
            {
                auto gen = RefCounted!EventGenerator.make;
                {
                    auto rec1 = RefCounted!EventReciever.make("Fizz");
                    auto rec2 = RefCounted!EventReciever.make("Buzz");
                    gen.v.handlers ~= autodlg(
                        (string s, typeof(rec1) rc){rc.v.recieve(s);}, rec1);
                    gen.v.handlers ~= autodlg(
                        (string s, typeof(rec2) rc){rc.v.recieve(s);}, rec2);
                }   // EventRecievers are still referenced from get.v.handlers array
                gen.v.raise("K");
                assert(equal(global_str, "FizzKBuzzK"));
            }
            // gen destroyed, array destructor destroys all closured.
            // no more references to EventRecievers, their destructors run.
            assert(equal(global_str, "FizzKBuzzKDD"));
        }
        // case 4
        {
            int x, y;
            float z = 0.0f;
            // autodlg is variadic, you can capture as many variables
            // as you need.
            Delegate!(float, float, float) ddlg =
                autodlg(
                    (float a, float b, int x, int y, float z) => a + b + x + y + z,
                    x, y, z);
            assert(ddlg(1.0f, 2.0f) == 3.0f);
        }
    }

    // If you want to use instantiated allocator:
    import std.experimental.allocator.showcase;
    alias AllocType = StackFront!(4096, Mallocator);
    AllocType allocator;
    // Note the AllocType*. Pointer to structure AllocType is used as
    // allocator, not the structure itself.
    alias StackFrontCtx = AllocationContext!(AllocType*, true);

    // Construct primitives like this:
    auto unq = StackFrontCtx.Unique!(int).make(&allocator, 5);
    assert(unq.v == 5);
    auto rcp = StackFrontCtx.RefCounted!(int).make(&allocator, 5);
    assert(rcp.v == 5);
    auto ddlg = StackFrontCtx.autodlg(&allocator, (int* x) { *x = 4; });
    int k = 0;
    ddlg(&k);
    assert(k == 4);
}