#include "il2cpp-config.h"

#if IL2CPP_GC_BOEHM

#include <stdint.h>
#include "gc_wrapper.h"
#include "GarbageCollector.h"
#include "WriteBarrier.h"
#include "WriteBarrierValidation.h"
#include "os/Mutex.h"
#include "vm/Array.h"
#include "vm/Domain.h"
#include "vm/MetadataCache.h"
#include "vm/Profiler.h"
#include "utils/Il2CppHashMap.h"
#include "utils/HashUtils.h"
#include "il2cpp-object-internals.h"

#include "Baselib.h"
#include "Cpp/ReentrantLock.h"

static bool s_GCInitialized = false;

#if IL2CPP_ENABLE_DEFERRED_GC
static bool s_PendingGC = false;
#endif

static void on_gc_event(GC_EventType eventType);
#if IL2CPP_ENABLE_PROFILER
using il2cpp::vm::Profiler;
static void on_heap_resize(GC_word newSize);
#endif

static GC_push_other_roots_proc default_push_other_roots;
typedef Il2CppHashMap<char*, char*, il2cpp::utils::PassThroughHash<char*> > RootMap;
static RootMap s_Roots;
static void push_other_roots(void);

typedef struct ephemeron_node ephemeron_node;
static ephemeron_node* ephemeron_list;

static void
clear_ephemerons(void);

static GC_ms_entry*
push_ephemerons(GC_ms_entry* mark_stack_ptr, GC_ms_entry* mark_stack_limit);

static unsigned push_roots_proc_index;

static GC_ms_entry*
push_roots(GC_word* addr, GC_ms_entry* mark_stack_ptr, GC_ms_entry* mark_stack_limit, GC_word env);

#if !IL2CPP_ENABLE_WRITE_BARRIER_VALIDATION
#define ELEMENT_CHUNK_SIZE 256
#define VECTOR_PROC_INDEX 6

#define BYTES_PER_WORD (sizeof(GC_word))

#include <gc_vector.h>

GC_ms_entry* GC_gcj_vector_proc(GC_word* addr, GC_ms_entry* mark_stack_ptr,
    GC_ms_entry* mark_stack_limit, GC_word env)
{
    Il2CppArraySize* a = NULL;
    if (env)
    {
        IL2CPP_ASSERT(env == 1);

        a = (Il2CppArraySize*)GC_base(addr);
    }
    else
    {
        IL2CPP_ASSERT(addr == GC_base(addr));

        a = (Il2CppArraySize*)addr;
    }

    if (!a->max_length)
        return mark_stack_ptr;

    il2cpp_array_size_t length = a->max_length;
    Il2CppClass* array_type = a->vtable->klass;
    Il2CppClass* element_type = array_type->element_class;
    GC_descr element_desc = (GC_descr)element_type->gc_desc;

    IL2CPP_ASSERT((element_desc & GC_DS_TAGS) == GC_DS_BITMAP);
    IL2CPP_ASSERT(element_type->byval_arg.valuetype);

    int words_per_element = array_type->element_size / BYTES_PER_WORD;
    GC_word* actual_start = (GC_word*)a->vector;

    /* start at first element or resume from last iteration */
    GC_word* start = env ? addr : actual_start;
    /* end at last element or max chunk size */
    GC_word* actual_end = actual_start + length * words_per_element;

    return GC_gcj_vector_mark_proc(mark_stack_ptr, mark_stack_limit, element_desc, start, actual_end, words_per_element);
}

#endif // !IL2CPP_ENABLE_WRITE_BARRIER_VALIDATION

void
il2cpp::gc::GarbageCollector::Initialize()
{
    if (s_GCInitialized)
        return;

#if IL2CPP_ENABLE_WRITE_BARRIER_VALIDATION
    il2cpp::gc::WriteBarrierValidation::Setup();
#endif
    // This tells the GC that we are not scanning dynamic library data segments and that
    // the GC tracked data structures need ot be manually pushed and marked.
    // Call this before GC_INIT since the initialization logic uses this value.
    GC_set_no_dls(1);

#if !IL2CPP_DEVELOPMENT
    // Turn off GC logging and warnings for non-development builds
    GC_set_warn_proc(GC_ignore_warn_proc);
#endif

#if IL2CPP_ENABLE_WRITE_BARRIERS
    GC_enable_incremental();
#if IL2CPP_INCREMENTAL_TIME_SLICE
    GC_set_time_limit(IL2CPP_INCREMENTAL_TIME_SLICE);
#endif
#endif

    push_roots_proc_index = GC_new_proc(push_roots);
    default_push_other_roots = GC_get_push_other_roots();
    GC_set_push_other_roots(push_other_roots);
    GC_set_mark_stack_empty(push_ephemerons);

    GC_set_on_collection_event(&on_gc_event);
#if IL2CPP_ENABLE_PROFILER
    GC_set_on_heap_resize(&on_heap_resize);
#endif

    GC_INIT();
    // Always manually trigger finalizers. This is done by the notifier callback registered
    // below on the majority of platforms. On the Web platform we trigger finalizers if needed
    // in CollectALittle which is called at top of each frame.
    GC_set_finalize_on_demand(1);
#if defined(GC_THREADS)
    GC_set_finalizer_notifier(&il2cpp::gc::GarbageCollector::NotifyFinalizers);
    // We need to call this if we want to manually register threads, i.e. GC_register_my_thread
    #if !IL2CPP_TARGET_JAVASCRIPT
    GC_allow_register_threads();
    #endif
#endif
#ifdef GC_GCJ_SUPPORT
    GC_init_gcj_malloc(0, NULL);
#endif

#if !IL2CPP_ENABLE_WRITE_BARRIER_VALIDATION
    GC_init_gcj_vector(VECTOR_PROC_INDEX, (void*)GC_gcj_vector_proc);
#endif
    s_GCInitialized = true;
}

void il2cpp::gc::GarbageCollector::UninitializeGC()
{
#if IL2CPP_ENABLE_WRITE_BARRIER_VALIDATION
    il2cpp::gc::WriteBarrierValidation::Run();
#endif
    GC_deinit();
#if IL2CPP_ENABLE_RELOAD
    s_GCInitialized = false;
    default_push_other_roots = NULL;
    s_Roots.clear();
#endif
}

int32_t
il2cpp::gc::GarbageCollector::GetCollectionCount(int32_t generation)
{
    return (int32_t)GC_get_gc_no();
}

int32_t
il2cpp::gc::GarbageCollector::GetMaxGeneration()
{
    return 0;
}

void
il2cpp::gc::GarbageCollector::Collect(int maxGeneration)
{
#if IL2CPP_ENABLE_DEFERRED_GC
    if (GC_is_disabled())
        s_PendingGC = true;
#endif
    GC_gcollect();
}

int32_t
il2cpp::gc::GarbageCollector::CollectALittle()
{
#if IL2CPP_ENABLE_DEFERRED_GC
    // This should only be called from Unity at the top of stack
    // with the GC enabled.

    IL2CPP_ASSERT(!GC_is_disabled());
    int32_t ret = 0;
    if (s_PendingGC)
    {
        s_PendingGC = false;
        GC_gcollect();
        ret = 0; // no more work to do
    }
    else
    {
        ret = GC_collect_a_little();
    }

    // Disable the GC to run finalizers, as they may allocate and interact with managed memory.
    GC_disable();
    // this checks and only runs finalizers if there is work to do
    GarbageCollector::WaitForPendingFinalizers();
    GC_enable();
    return ret;
#else
    return GC_collect_a_little();
#endif
}

void
il2cpp::gc::GarbageCollector::StartIncrementalCollection()
{
    GC_start_incremental_collection();
}

#if IL2CPP_ENABLE_WRITE_BARRIERS
void
il2cpp::gc::GarbageCollector::SetWriteBarrier(void **ptr)
{
    GC_END_STUBBORN_CHANGE(ptr);
}

#endif

int64_t
il2cpp::gc::GarbageCollector::GetUsedHeapSize(void)
{
    return GC_get_heap_size() - GC_get_free_bytes();
}

int64_t
il2cpp::gc::GarbageCollector::GetAllocatedHeapSize(void)
{
    return GC_get_heap_size();
}

void
il2cpp::gc::GarbageCollector::Disable()
{
    GC_disable();
}

void
il2cpp::gc::GarbageCollector::Enable()
{
    GC_enable();
}

bool
il2cpp::gc::GarbageCollector::IsDisabled()
{
    return GC_is_disabled();
}

static baselib::ReentrantLock s_GCSetModeLock;
static Il2CppGCMode s_CurrentGCMode = IL2CPP_GC_MODE_ENABLED;

void
il2cpp::gc::GarbageCollector::SetMode(Il2CppGCMode mode)
{
    os::FastAutoLock lock(&s_GCSetModeLock);
    switch (mode)
    {
        case IL2CPP_GC_MODE_ENABLED:
            if (s_CurrentGCMode == IL2CPP_GC_MODE_DISABLED)
                GC_enable();
            GC_set_disable_automatic_collection(false);
            break;

        case IL2CPP_GC_MODE_DISABLED:
            if (s_CurrentGCMode != IL2CPP_GC_MODE_DISABLED)
                GC_disable();
            break;

        case IL2CPP_GC_MODE_MANUAL:
            if (s_CurrentGCMode == IL2CPP_GC_MODE_DISABLED)
                GC_enable();
            GC_set_disable_automatic_collection(true);
            break;
    }

    s_CurrentGCMode = mode;
}

void
il2cpp::gc::GarbageCollector::RegisterThread()
{
#if defined(GC_THREADS) && !IL2CPP_TARGET_JAVASCRIPT
    struct GC_stack_base sb;
    int res;

    res = GC_get_stack_base(&sb);
    if (res != GC_SUCCESS)
    {
        /* Can't determine the register stack bounds */
        IL2CPP_ASSERT(false && "GC_get_stack_base () failed, aborting.");
        /* Abort we can't scan the stack, so we can't use the GC */
        abort();
    }
    res = GC_register_my_thread(&sb);
    if ((res != GC_SUCCESS) && (res != GC_DUPLICATE))
    {
        IL2CPP_ASSERT(false && "GC_register_my_thread () failed.");
        /* Abort we can't use the GC on this thread, so we can't run managed code */
        abort();
    }
#endif
}

bool
il2cpp::gc::GarbageCollector::UnregisterThread()
{
#if defined(GC_THREADS) && !IL2CPP_TARGET_JAVASCRIPT
    int res;

    res = GC_unregister_my_thread();
    if (res != GC_SUCCESS)
        IL2CPP_ASSERT(false && "GC_unregister_my_thread () failed.");

    return res == GC_SUCCESS;
#else
    return true;
#endif
}

il2cpp::gc::GarbageCollector::FinalizerCallback il2cpp::gc::GarbageCollector::RegisterFinalizerWithCallback(Il2CppObject* obj, FinalizerCallback callback)
{
    FinalizerCallback oldCallback;
    void* oldData;
    GC_REGISTER_FINALIZER_NO_ORDER((char*)obj, callback, NULL, &oldCallback, &oldData);
    IL2CPP_ASSERT(oldData == NULL);
    return oldCallback;
}

void
il2cpp::gc::GarbageCollector::AddWeakLink(void **link_addr, Il2CppObject *obj, bool track)
{
    /* libgc requires that we use HIDE_POINTER... */
    *link_addr = (void*)GC_HIDE_POINTER(obj);
    // need this since our strings are not real objects
    if (GC_is_heap_ptr(obj))
        GC_GENERAL_REGISTER_DISAPPEARING_LINK(link_addr, obj);
}

void
il2cpp::gc::GarbageCollector::RemoveWeakLink(void **link_addr)
{
    Il2CppObject*  obj = GarbageCollector::GetWeakLink(link_addr);
    if (GC_is_heap_ptr(obj))
        GC_unregister_disappearing_link(link_addr);
    *link_addr = NULL;
}

static void*
RevealLink(void* link_addr)
{
    void **link_a = (void**)link_addr;
    return GC_REVEAL_POINTER(*link_a);
}

Il2CppObject*
il2cpp::gc::GarbageCollector::GetWeakLink(void **link_addr)
{
    Il2CppObject *obj = (Il2CppObject*)GC_call_with_alloc_lock(RevealLink, link_addr);
    if (obj == (Il2CppObject*)-1)
        return NULL;
    return obj;
}

void*
il2cpp::gc::GarbageCollector::MakeDescriptorForObject(size_t *bitmap, int numbits)
{
#ifdef GC_GCJ_SUPPORT

    /* It seems there are issues when the bitmap doesn't fit: play it safe */
#define MAX_GC_DESCR_BITS   (IL2CPP_SIZEOF_VOID_P * 8 - GC_DS_TAG_BITS)

    if (numbits >= MAX_GC_DESCR_BITS)
        return GC_NO_DESCRIPTOR;
    else
    {
        GC_descr desc = GC_make_descriptor((GC_bitmap)bitmap, numbits);
        // we should always have a GC_DS_BITMAP descriptor, as we:
        // 1) Always want a precise marker.
        // 2) Can never be GC_DS_LENGTH since we always have an object header
        //    at the beginning of the allocation.
        IL2CPP_ASSERT((desc & GC_DS_TAGS) == GC_DS_BITMAP || (desc & GC_DS_TAGS) == (GC_descr)GC_NO_DESCRIPTOR);
        return (void*)desc;
    }
#else
    return 0;
#endif
}

void* il2cpp::gc::GarbageCollector::MakeEmptyDescriptor()
{
    return GC_NO_DESCRIPTOR;
}

void* il2cpp::gc::GarbageCollector::MakeDescriptorForString()
{
    return GC_NO_DESCRIPTOR;
}

void* il2cpp::gc::GarbageCollector::MakeDescriptorForArray()
{
    return GC_NO_DESCRIPTOR;
}

void il2cpp::gc::GarbageCollector::StopWorld()
{
    // Acquire all the metadata locks before stopping the world
    // This ensures that while the GC is stopped we can safely query
    // internal metadata without worrying about a paused thread holding those locks
    vm::MetadataCache::AcquireMetadataLocks();

    GC_stop_world_external();

    // Some of these locks are not re-entrant so we want to release them here
    // Once all threads are stopped there's no reason to keep these locked
    vm::MetadataCache::ReleaseMetadataLocks();
}

void il2cpp::gc::GarbageCollector::StartWorld()
{
    GC_start_world_external();
}

void*
il2cpp::gc::GarbageCollector::AllocateFixed(size_t size, void *descr)
{
    // Note that we changed the implementation from mono.
    // In our case, we expect that
    // a) This memory will never be moved
    // b) This memory will be scanned for references
    // c) This memory will remain 'alive' until explicitly freed
    // GC_MALLOC_UNCOLLECTABLE fulfills all these requirements
    // It does not accept a descriptor, but there was only one
    // or two places in mono that pass a descriptor to this routine
    // and we can or will support those use cases in a different manner.
    IL2CPP_ASSERT(!descr);

    return GC_MALLOC_UNCOLLECTABLE(size);
}

void
il2cpp::gc::GarbageCollector::FreeFixed(void* addr)
{
    GC_FREE(addr);
}

int32_t
il2cpp::gc::GarbageCollector::InvokeFinalizers()
{
    return (int32_t)GC_invoke_finalizers();
}

bool
il2cpp::gc::GarbageCollector::HasPendingFinalizers()
{
    return GC_should_invoke_finalizers() != 0;
}

int64_t
il2cpp::gc::GarbageCollector::GetMaxTimeSliceNs()
{
    return GC_get_time_limit_ns();
}

void
il2cpp::gc::GarbageCollector::SetMaxTimeSliceNs(int64_t maxTimeSlice)
{
    GC_set_time_limit_ns(maxTimeSlice);
}

bool
il2cpp::gc::GarbageCollector::IsIncremental()
{
    return GC_is_incremental_mode();
}

void on_gc_event(GC_EventType eventType)
{
    if (eventType == GC_EVENT_RECLAIM_START)
    {
        clear_ephemerons();
    }
#if IL2CPP_ENABLE_PROFILER
    Profiler::GCEvent((Il2CppGCEvent)eventType);
#endif
}

#if IL2CPP_ENABLE_PROFILER

void on_heap_resize(GC_word newSize)
{
    Profiler::GCHeapResize((int64_t)newSize);
}

#endif // IL2CPP_ENABLE_PROFILER

typedef struct
{
    void* user_data;
    il2cpp::gc::GarbageCollector::HeapSectionCallback callback;
} HeapSectionExecutionContext;

static void HeapSectionAdaptor(void* userData, GC_PTR chunk_start, GC_PTR chunk_end, GC_heap_section_type type)
{
    HeapSectionExecutionContext* ctx = (HeapSectionExecutionContext*)userData;
    ctx->callback(ctx->user_data, chunk_start, chunk_end);
}

void il2cpp::gc::GarbageCollector::ForEachHeapSection(void* user_data, HeapSectionCallback callback)
{
    HeapSectionExecutionContext ctx {user_data, callback};
    GC_foreach_heap_section(&ctx, HeapSectionAdaptor);
}

static void HeapSectionCountIncrementer(void* userData, GC_PTR start, GC_PTR end, GC_heap_section_type type)
{
    size_t* countPtr = (size_t*)userData;
    (*countPtr)++;
}

size_t il2cpp::gc::GarbageCollector::GetSectionCount()
{
    size_t counter = 0;
    GC_foreach_heap_section(&counter, HeapSectionCountIncrementer);
    return counter;
}

void* il2cpp::gc::GarbageCollector::CallWithAllocLockHeld(GCCallWithAllocLockCallback callback, void* user_data)
{
    return GC_call_with_alloc_lock(callback, user_data);
}

typedef struct
{
    char *start;
    char *end;
} RootData;


static void*
register_root(void* arg)
{
    RootData* root_data = (RootData*)arg;
    s_Roots.insert(std::make_pair(root_data->start, root_data->end));
    return NULL;
}

void il2cpp::gc::GarbageCollector::RegisterRoot(char *start, size_t size)
{
    RootData root_data;
    root_data.start = start;
    /* Boehm root processing requires one byte past end of region to be scanned */
    root_data.end = start + size + 1;
    CallWithAllocLockHeld(register_root, &root_data);
}

static void*
deregister_root(void* arg)
{
    s_Roots.erase((char*)arg);
    return NULL;
}

void il2cpp::gc::GarbageCollector::UnregisterRoot(char* start)
{
    GC_call_with_alloc_lock(deregister_root, start);
}

static GC_ms_entry*
push_roots(GC_word* addr, GC_ms_entry* mark_stack_ptr, GC_ms_entry* mark_stack_limit, GC_word env)
{
    auto size = s_Roots.size();

    GC_word capacity = (GC_word)(mark_stack_limit - mark_stack_ptr) - 1;
    GC_word start_index = (GC_word)(intptr_t)addr;
    GC_word remaining = size - start_index;
    GC_word skip = start_index;

    /* if we have more items than capacity, push remaining immediately. This allows pushed
     * items to be processed on top of stack before we process remainder. If we push remainder
     * at top, we have no mark stack space.
     */
    if (remaining > capacity)
    {
        capacity--;
        mark_stack_ptr = GC_custom_push_proc(GC_MAKE_PROC(push_roots_proc_index, (start_index + capacity)), (void*)(start_index + capacity), mark_stack_ptr, mark_stack_limit);
    }

    for (RootMap::const_iterator iter = s_Roots.begin(); iter != s_Roots.end() && capacity > 0; ++iter)
    {
        if (skip)
        {
            skip--;
            continue;
        }

        mark_stack_ptr = GC_custom_push_range(iter->first, iter->second, mark_stack_ptr, mark_stack_limit);

        capacity--;
    }
    return mark_stack_ptr;
}

static void
push_other_roots(void)
{
    if (push_roots_proc_index)
        GC_push_proc(GC_MAKE_PROC(push_roots_proc_index, 0), NULL);

    GC_push_all(&ephemeron_list, &ephemeron_list + 1);
    if (default_push_other_roots)
        default_push_other_roots();
}

struct ephemeron_node
{
    ephemeron_node* next;
    void* ephemeron_array_weak_link;
};


static void*
ephemeron_array_add(void* arg)
{
    ephemeron_node* item = (ephemeron_node*)arg;
    ephemeron_node* current = ephemeron_list;
    il2cpp::gc::WriteBarrier::GenericStore(&item->next, current);
    ephemeron_list = item;

    return NULL;
}

struct Ephemeron
{
    Il2CppObject* key;
    Il2CppObject* value;
};

static void
clear_ephemerons(void)
{
    ephemeron_node* prev_node = NULL;
    ephemeron_node* current_node = NULL;

    /* iterate all registered Ephemeron[] */
    for (current_node = ephemeron_list; current_node; current_node = current_node->next)
    {
        Ephemeron* current_ephemeron, * array_end;
        Il2CppObject* tombstone = NULL;
        /* reveal weak link value*/
        Il2CppArray* array = (Il2CppArray*)GC_REVEAL_POINTER(current_node->ephemeron_array_weak_link);

        /* remove unmarked (non-reachable) arrays from the list */
        if (!GC_is_marked(array))
        {
            if (prev_node == NULL)
                il2cpp::gc::WriteBarrier::GenericStore(&ephemeron_list, current_node->next);
            else
                il2cpp::gc::WriteBarrier::GenericStore(&prev_node->next, current_node->next);
            continue;
        }

        prev_node = current_node;

        current_ephemeron = il2cpp_array_addr(array, Ephemeron, 0);
        array_end = current_ephemeron + array->max_length;
        tombstone = il2cpp::vm::Domain::GetCurrent()->ephemeron_tombstone;

        for (; current_ephemeron < array_end; ++current_ephemeron)
        {
            /* skip a null or tombstone (empty) key */
            if (!current_ephemeron->key || current_ephemeron->key == tombstone)
                continue;

            /* If the key is not marked, then set it to the tombstone and the value to NULL. */
            if (!GC_is_marked(current_ephemeron->key))
            {
                il2cpp::gc::WriteBarrier::GenericStore(&current_ephemeron->key, tombstone);
                current_ephemeron->value = NULL;
            }
        }
    }
}

static GC_ms_entry*
push_ephemerons(GC_ms_entry* mark_stack_ptr, GC_ms_entry* mark_stack_limit)
{
    ephemeron_node* prev_node = NULL;
    ephemeron_node* current_node = NULL;

    /* iterate all registered Ephemeron[] */
    for (current_node = ephemeron_list; current_node; current_node = current_node->next)
    {
        Ephemeron* current_ephemeron, * array_end;
        Il2CppObject* tombstone = NULL;
        /* reveal weak link value*/
        Il2CppArray* array = (Il2CppArray*)GC_REVEAL_POINTER(current_node->ephemeron_array_weak_link);

        /* unreferenced array */
        if (!GC_is_marked(array))
        {
            continue;
        }

        prev_node = current_node;

        current_ephemeron = il2cpp_array_addr(array, Ephemeron, 0);
        array_end = current_ephemeron + array->max_length;
        tombstone = il2cpp::vm::Domain::GetCurrent()->ephemeron_tombstone;

        for (; current_ephemeron < array_end; ++current_ephemeron)
        {
            /* skip a null or tombstone (empty) key */
            if (!current_ephemeron->key || current_ephemeron->key == tombstone)
                continue;

            /* If the key is not marked, then don't mark value. */
            if (!GC_is_marked(current_ephemeron->key))
                continue;

            if (current_ephemeron->value)
            {
                mark_stack_ptr = GC_mark_and_push((void*)current_ephemeron->value, mark_stack_ptr, mark_stack_limit, (void**)&current_ephemeron->value);
            }
        }
    }

    return mark_stack_ptr;
}

bool il2cpp::gc::GarbageCollector::EphemeronArrayAdd(Il2CppObject* obj)
{
    ephemeron_node* item = (ephemeron_node*)GC_MALLOC(sizeof(ephemeron_node));
    memset(item, 0, sizeof(ephemeron_node));

    AddWeakLink(&item->ephemeron_array_weak_link, obj, false);

    GC_call_with_alloc_lock(ephemeron_array_add, item);
    return true;
}

#endif
