/** @file DX1Collector.cpp
 *
 *  @author Roland Conybeare, Dec 2025
 **/

#include "Allocator.hpp"
#include "arena/IAllocator_DArena.hpp"
#include "gc/DX1Collector.hpp"
#include "gc/generation.hpp"
#include <xo/facet/obj.hpp>
#include <cassert>
#include <cstdint>

namespace xo {
    using xo::mm::AAllocator;
    using xo::facet::with_facet;

    namespace mm {
#ifdef NOT_USING
        constexpr std::uint64_t
        CollectorConfig::gen_mult() const {
            return 1ul << arena_config_.header_size_bits_;
        }
#endif

        constexpr std::uint64_t
        CollectorConfig::gen_shift() const {
            return arena_config_.header_size_bits_;
        }

        constexpr std::uint64_t
        CollectorConfig::gen_mask_unshifted() const {
            return (1ul << gen_bits_) - 1;
        }

        constexpr std::uint64_t
        CollectorConfig::gen_mask_shifted() const {
            return gen_mask_unshifted() << arena_config_.header_size_bits_;
        }

#ifdef NOT_USING
        constexpr std::uint64_t
        CollectorConfig::tseq_mult() const {
            return 1ul << (gen_bits_ + arena_config_.header_size_bits_);
        }
#endif

        constexpr std::uint64_t
        CollectorConfig::tseq_shift() const {
            return gen_bits_ + arena_config_.header_size_bits_;
        }

        constexpr std::uint64_t
        CollectorConfig::tseq_mask_unshifted() const {
            return (1ul << tseq_bits_) - 1;
        }

        constexpr std::uint64_t
        CollectorConfig::tseq_mask_shifted() const {
            return tseq_mask_unshifted() << (gen_bits_ + arena_config_.header_size_bits_);
        }

        // ----- GCRunState -----

        GCRunState::GCRunState(generation gc_upto)
            : gc_upto_{gc_upto}
        {}

        GCRunState
        GCRunState::gc_not_running()
        {
            return GCRunState(generation(0));
        }

        GCRunState
        GCRunState::gc_upto(generation g)
        {
            return GCRunState(generation(g + 1));
        }

        // ----- DX1Collector -----

        using size_type = xo::mm::DX1Collector::size_type;

        DX1Collector::DX1Collector(const CollectorConfig & cfg) : config_{cfg}
        {
            assert(config_.arena_config_.header_size_bits_ + config_.gen_bits_ + config_.tseq_bits_ <= 64);

            for (uint32_t igen = 0, ngen = cfg.n_generation_; igen < ngen; ++igen) {
                space_storage_[0][igen] = DArena::map(cfg.arena_config_);
                space_storage_[1][igen] = DArena::map(cfg.arena_config_);

                space_[role::to_space()][igen] = &space_storage_[0][igen];
                space_[role::from_space()][igen] = &space_storage_[1][igen];
            }

            for (uint32_t igen = cfg.n_generation_; igen < c_max_generation; ++igen) {
                space_[role::to_space()][igen] = nullptr;
                space_[role::from_space()][igen] = nullptr;
            }
        }

        bool
        DX1Collector::contains(role r, const void * addr) const noexcept
        {
            for (generation gi{0}; gi < config_.n_generation_; ++gi) {
                const DArena * arena = get_space(r, gi);

                if (arena->contains(addr))
                    return true;
            }

            return false;
        }

        AllocatorError
        DX1Collector::last_error() const noexcept
        {
            // TODO:
            // need to adjust here if runtime errors
            // encountered during gc.

            return get_space(role::to_space(), generation::nursery())->last_error_;
        }

        namespace {
            size_type
            accumulate_total_aux(const DX1Collector & d,
                                 size_t (DArena::* get_stat_fn)() const) noexcept
            {
                size_t z = 0;

                for (role ri : role::all()) {
                    for (generation gj{0}; gj < d.config_.n_generation_; ++gj) {
                        const DArena * arena = d.get_space(ri, gj);

                        assert(arena);

                        z += (arena->*get_stat_fn)();
                    }
                }

                return z;
            }
        }

        size_type
        DX1Collector::reserved_total() const noexcept
        {
            return accumulate_total_aux(*this, &DArena::reserved);
        }

        size_type
        DX1Collector::size_total() const noexcept
        {
            return committed_total();
        }

        size_type
        DX1Collector::committed_total() const noexcept
        {
            return accumulate_total_aux(*this, &DArena::committed);
        }

        size_type
        DX1Collector::available_total() const noexcept
        {
            return accumulate_total_aux(*this, &DArena::available);
        }

        size_type
        DX1Collector::allocated_total() const noexcept
        {
            return accumulate_total_aux(*this, &DArena::allocated);
        }

        size_type
        DX1Collector::header2size(header_type hdr) const noexcept
        {
            uint32_t z = (hdr & config_.arena_config_.header_size_mask_);

            return z;
        }

        generation
        DX1Collector::header2gen(header_type hdr) const noexcept
        {
            uint32_t g = (hdr & config_.gen_mask_shifted()) >> config_.gen_shift();

            assert(g < c_max_generation);

            return generation(g);
        }

        uint32_t
        DX1Collector::header2tseq(header_type hdr) const noexcept
        {
            uint32_t tseq = (hdr & config_.tseq_mask_shifted()) >> config_.tseq_shift();

            return tseq;
        }

        bool
        DX1Collector::is_forwarding_header(header_type hdr) const noexcept
        {
            /** all 1 bits to flag forwarding pointer **/
            return header2tseq(hdr) == config_.tseq_mask_shifted();
        }

        auto
        DX1Collector::alloc(size_type z) noexcept -> value_type
        {
            return with_facet<AAllocator>::mkobj(new_space()).alloc(z);
        }

        auto
        DX1Collector::super_alloc(size_type z) noexcept -> value_type {
            return with_facet<AAllocator>::mkobj(new_space()).super_alloc(z);
        }

        auto
        DX1Collector::sub_alloc(size_type z, bool complete) noexcept -> value_type {
            return with_facet<AAllocator>::mkobj(new_space()).sub_alloc(z, complete);
        }

        bool
        DX1Collector::expand(size_type z) noexcept
        {
            if (with_facet<AAllocator>::mkobj(to_space(generation{0})).expand(z))
                return with_facet<AAllocator>::mkobj(from_space(generation{0})).expand(z);

            return false;
        }

        void
        DX1Collector::reverse_roles(generation g) noexcept {
            assert(g < config_.n_generation_);

            std::swap(space_[0][g], space_[1][g]);
        }

        void
        DX1Collector::clear() noexcept {
            for (role ri : role::all()) {
                for (generation gj{0}; gj < config_.n_generation_; ++gj) {
                    DArena * arena = this->get_space(ri, gj);

                    assert(arena);

                    arena->clear();
                }
            }
        }
    } /*namespace mm*/
} /*namespace xo*/

/* end DX1Collector.cpp */