// hak_free_api.inc.h — Box: hak_free_at() implementation
// Phase 15: Box Separation - One-way routing (FG → Domain boxes → ExternalGuard)
#ifndef HAK_FREE_API_INC_H
#define HAK_FREE_API_INC_H

#include <sys/mman.h>  // For mincore() in AllocHeader safety check
#include "hakmem_tiny_superslab.h"  // For SUPERSLAB_MAGIC, SuperSlab
#include "../ptr_trace.h"              // Debug: pointer trace immediate dump on libc fallback
#include "../hakmem_trace_master.h"    // Unified trace control (HAKMEM_TRACE + per-feature ENV)
#include "front_gate_v2.h"           // Phase 15: Box FG V2 - 1-byte header classification
#include "external_guard_box.h"      // Phase 15: Box ExternalGuard - mincore (ENV controlled)
#include "fg_tiny_gate_box.h"        // Tiny gate guard box (Superslab check)
#include "tiny_free_gate_box.h"      // Tiny Free Gatekeeper Box (USER→Fast Path 境界)
#include "free_dispatch_stats_box.h" // Phase FREE-DISPATCHER-OPT-1: free dispatcher stats
#include "region_id_v6_box.h"        // Phase MID-V3: RegionIdBox for ownership lookup
#include "mid_hotbox_v3_box.h"       // Phase MID-V3: Mid/Pool HotBox v3 types
#include "mid_hotbox_v3_env_box.h"   // Phase MID-V3: ENV gate for v3

#ifdef HAKMEM_POOL_TLS_PHASE1
#include "../pool_tls.h"
#endif

#include "mid_large_config_box.h"  // Phase 5-Step3: Compile-time config for Mid/Large

// Optional route trace: print first N classification lines when enabled by env
#if !HAKMEM_BUILD_RELEASE
static inline int hak_free_route_trace_on(void) {
    static int g_trace = -1;
    if (__builtin_expect(g_trace == -1, 0)) {
        // Unified trace: HAKMEM_FREE_ROUTE_TRACE or HAKMEM_TRACE=free
        g_trace = hak_trace_check("HAKMEM_FREE_ROUTE_TRACE", "free");
    }
    return g_trace;
}
static inline int* hak_free_route_budget_ptr(void) {
    static int g_budget = 32; // first 32 frees only
    return &g_budget;
}
static inline void hak_free_route_log(const char* tag, void* p) {
    if (!hak_free_route_trace_on()) return;
    int* budget = hak_free_route_budget_ptr();
    if (*budget <= 0) return;
    (*budget)--;
    fprintf(stderr, "[FREE_ROUTE] %s ptr=%p\n", tag, p);
}
#else
static inline void hak_free_route_log(const char* tag, void* p) { (void)tag; (void)p; }
#endif

// Optional: request-trace for invalid-magic cases (first N hits)
static inline int hak_super_reg_reqtrace_on(void) {
    static int g_on = -1;
    if (__builtin_expect(g_on == -1, 0)) {
        // Unified trace: HAKMEM_SUPER_REG_REQTRACE or HAKMEM_TRACE=registry
        g_on = hak_trace_check("HAKMEM_SUPER_REG_REQTRACE", "registry");
    }
    return g_on;
}
static inline int* hak_super_reg_reqtrace_budget_ptr(void) {
    static int g_budget = 16; // trace first 16 occurrences
    return &g_budget;
}
static inline void hak_super_reg_reqtrace_dump(void* ptr) {
    if (!hak_super_reg_reqtrace_on()) return;
    int* b = hak_super_reg_reqtrace_budget_ptr();
    if (*b <= 0) return;
    (*b)--;
    uintptr_t p = (uintptr_t)ptr;
    uintptr_t m20 = ((uintptr_t)1 << 20) - 1;
    uintptr_t m21 = ((uintptr_t)1 << 21) - 1;
    SuperSlab* s20 = (SuperSlab*)(p & ~m20);
    SuperSlab* s21 = (SuperSlab*)(p & ~m21);
    unsigned long long mg20 = 0, mg21 = 0;
    // Best-effort reads (may be unmapped; wrap in volatile access)
    mg20 = (unsigned long long)(s20 ? s20->magic : 0);
    mg21 = (unsigned long long)(s21 ? s21->magic : 0);
    fprintf(stderr,
            "[SUPER_REG_REQTRACE] ptr=%p base1M=%p magic1M=0x%llx base2M=%p magic2M=0x%llx\n",
            ptr, (void*)s20, mg20, (void*)s21, mg21);
}

#ifndef HAKMEM_TINY_PHASE6_BOX_REFACTOR
__attribute__((always_inline))
inline
#endif
void hak_free_at(void* ptr, size_t size, hak_callsite_t site) {
    // Phase FREE-DISPATCHER-OPT-1: Total call counter (at function entry)
    FREE_DISPATCH_STAT_INC(total_calls);

#if HAKMEM_DEBUG_TIMING
    HKM_TIME_START(t0);
#endif
    static _Atomic int g_hak_free_at_trace = 0;
    if (atomic_fetch_add_explicit(&g_hak_free_at_trace, 1, memory_order_relaxed) < 128) {
        HAK_TRACE("[hak_free_at_enter]\n");
    }
    (void)site; (void)size;
    int fg_misclass = 0;  // Set when FG said Tiny but registry rejects
    // Optional lightweight trace of early free calls (first few only)
#if !HAKMEM_BUILD_RELEASE
    static int free_trace_en = -1; static _Atomic int free_trace_count = 0;
    if (__builtin_expect(free_trace_en == -1, 0)) {
        // Unified trace: HAKMEM_FREE_WRAP_TRACE or HAKMEM_TRACE=free
        free_trace_en = hak_trace_check("HAKMEM_FREE_WRAP_TRACE", "free");
    }
    if (free_trace_en) {
        int n = atomic_fetch_add(&free_trace_count, 1);
        if (n < 8) {
            fprintf(stderr, "[FREE_WRAP_ENTER] ptr=%p\n", ptr);
        }
    }
#endif
    // Bench-only ultra-short path: try header-based tiny fast free first
    // Enable with: HAKMEM_BENCH_FAST_FRONT=1
    {
        static int g_bench_fast_front = -1;
        if (__builtin_expect(g_bench_fast_front == -1, 0)) {
            const char* e = getenv("HAKMEM_BENCH_FAST_FRONT");
            g_bench_fast_front = (e && *e && *e != '0') ? 1 : 0;
        }
#if HAKMEM_TINY_HEADER_CLASSIDX
        if (__builtin_expect(g_bench_fast_front && ptr != NULL, 0)) {
            if (__builtin_expect(tiny_free_gate_try_fast(ptr), 1)) {
#if HAKMEM_DEBUG_TIMING
                HKM_TIME_END(HKM_CAT_HAK_FREE, t0);
#endif
                return;
            }
        }
#endif
    }

    if (!ptr) {
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_END(HKM_CAT_HAK_FREE, t0);
#endif
        return;
    }

    // ========== Phase 15: Box FG V2 Classification ==========
    // One-way routing: FG → Domain boxes → ExternalGuard
    // Box FG V2: Ultra-fast 1-byte header classification (no mincore, no registry)
    fg_classification_t fg = fg_classify_domain(ptr);
    hak_free_route_log(fg_domain_name(fg.domain), ptr);

    // Fail-Fast: Tiny判定は Superslab 登録が必須。無ければ MIDCAND に戻す（箱化）。
    fg_tiny_gate_result_t fg_guard = fg_tiny_gate(ptr, fg);
    fg = fg_guard.fg;
    fg_misclass = fg_guard.misclassified;

    // Phase FREE-DISPATCHER-OPT-1: Domain classification counters
    if (__builtin_expect(free_dispatch_stats_enabled(), 0)) {
        switch (fg.domain) {
            case FG_DOMAIN_TINY:
                g_free_dispatch_stats.domain_tiny++;
                break;
            case FG_DOMAIN_MIDCAND:
            case FG_DOMAIN_POOL:
                g_free_dispatch_stats.domain_mid++;
                break;
            case FG_DOMAIN_EXTERNAL:
                g_free_dispatch_stats.domain_large++;
                break;
        }
    }

    switch (fg.domain) {
        case FG_DOMAIN_TINY: {
            // Phase FREE-FRONT-V3-2: v3 snapshot routing (optional, default OFF)
            // Optimized: No tiny_route_for_class() calls, no redundant ENV checks
#if HAKMEM_TINY_HEADER_CLASSIDX
            {
                // Check if v3 snapshot routing is enabled (cached)
                static int g_v3_enabled = -1;
                if (__builtin_expect(g_v3_enabled == -1, 0)) {
                    // For now, v3 snapshot routing is DISABLED by default (experimental)
                    // Phase v3-2 infrastructure is ready but not yet integrated
                    g_v3_enabled = 0;  // TODO: Enable when ready: free_front_v3_enabled() ? 1 : 0;
                }

                // Note: v3 snapshot path currently disabled (Phase v3-2 infrastructure only)
                // When enabled, it would consolidate free routing logic and remove redundant
                // ENV checks from the hot path. For now, use legacy routing below.
                (void)g_v3_enabled;  // Suppress unused variable warning
            }
#endif

            // Legacy path (default when v3 is OFF)
            // Fast path: Tiny (C0-C7) with 1-byte header (0xa0 | class_idx)
#if HAKMEM_TINY_HEADER_CLASSIDX
            if (__builtin_expect(tiny_free_gate_try_fast(ptr), 1)) {
#if !HAKMEM_BUILD_RELEASE
                hak_free_v2_track_fast();
#endif
                goto done;
            }
#if !HAKMEM_BUILD_RELEASE
            hak_free_v2_track_slow();
#endif
#endif
            hak_tiny_free(ptr);
            goto done;
        }

#ifdef HAKMEM_POOL_TLS_PHASE1
        case FG_DOMAIN_POOL: {
            // Pool TLS: 8KB-52KB allocations with 1-byte header (0xb0 | class_idx)
            pool_free(ptr);
            goto done;
        }
#endif

        case FG_DOMAIN_POOL:
        case FG_DOMAIN_MIDCAND:
        case FG_DOMAIN_EXTERNAL:
            // Fall through to registry lookup + AllocHeader dispatch
            break;
    }

    // ========== Slow Path: 16-byte AllocHeader Dispatch ==========
    // Handle Mid/Large allocations (malloc/mmap/Pool/L25)
    // Note: All Tiny allocations (C0-C7) already handled by Front Gate above

    // ========== Mid/L25/Tiny Registry Lookup (Headerless) ==========
    // MIDCAND: Could be Mid/Large/C7, needs registry lookup

    // Phase FREE-DISPATCH-SSOT: Single Source of Truth for region lookup
    // ENV: HAKMEM_FREE_DISPATCH_SSOT (default: 0 for backward compat, 1 for optimized)
    // Problem: Old code did region_id_lookup TWICE in MID-V3 path (once inside mid_hot_v3_free, once after)
    // Fix: Do lookup ONCE at top, dispatch based on kind
    static int g_free_dispatch_ssot = -1;
    if (__builtin_expect(g_free_dispatch_ssot == -1, 0)) {
        const char* env = getenv("HAKMEM_FREE_DISPATCH_SSOT");
        g_free_dispatch_ssot = (env && *env == '1') ? 1 : 0;
    }

    if (g_free_dispatch_ssot && __builtin_expect(mid_v3_enabled(), 0)) {
        // SSOT=1: Single lookup, then dispatch
        extern RegionLookupV6 region_id_lookup_cached_v6(void* ptr);
        RegionLookupV6 lk = region_id_lookup_cached_v6(ptr);

        if (lk.kind == REGION_KIND_MID_V3) {
            // Owned by MID-V3: call free handler directly (no internal lookup)
            // Note: We pass the pre-looked-up info implicitly via TLS cache
            mid_hot_v3_free(ptr);

            if (mid_v3_debug_enabled()) {
                static _Atomic int free_log_count = 0;
                if (atomic_fetch_add(&free_log_count, 1) < 10) {
                    fprintf(stderr, "[MID_V3] Free SSOT: ptr=%p\n", ptr);
                }
            }
            goto done;
        }
        // Not MID-V3: fall through to other dispatch paths below
    } else if (__builtin_expect(mid_v3_enabled(), 0)) {
        // SSOT=0: Legacy double-lookup path (for A/B comparison)
        // RegionIdBox lookup to check if v3 owns this pointer
        // mid_hot_v3_free() will check internally and return early if not owned
        mid_hot_v3_free(ptr);

        // Check if v3 actually owned it by doing a quick verification
        // For safety, check ownership explicitly before continuing
        // This prevents double-free if v3 handled it
        extern RegionLookupV6 region_id_lookup_v6(void* ptr);
        RegionLookupV6 lk = region_id_lookup_v6(ptr);
        if (lk.kind == REGION_KIND_MID_V3) {
            if (mid_v3_debug_enabled()) {
                static _Atomic int free_log_count = 0;
                if (atomic_fetch_add(&free_log_count, 1) < 10) {
                    fprintf(stderr, "[MID_V3] Free: ptr=%p\n", ptr);
                }
            }
            goto done;
        }
    }

    {
        extern int hak_pool_mid_lookup(void* ptr, size_t* out_size);
        extern void hak_pool_free_fast(void* ptr, uintptr_t site_id);
        size_t mid_sz = 0;
        if (hak_pool_mid_lookup(ptr, &mid_sz)) {
            hak_free_route_log("mid_hit", ptr);
            hak_pool_free_fast(ptr, (uintptr_t)site);
            goto done;
        }
    }
    {
        extern int hak_l25_lookup(void* ptr, size_t* out_size);
        extern void hak_l25_pool_free_fast(void* ptr, uintptr_t site_id);
        size_t l25_sz = 0;
        if (hak_l25_lookup(ptr, &l25_sz)) {
            hak_free_route_log("l25_hit", ptr);
            hkm_ace_stat_large_free();
            hak_l25_pool_free_fast(ptr, (uintptr_t)site);
            goto done;
        }
    }
    // PHASE 15: C7 (1KB headerless) registry lookup
    // Box FG V2 cannot classify C7 (no header), so use registry
    {
        SuperSlab* ss = hak_super_lookup(ptr);
        if (ss && ss->magic == SUPERSLAB_MAGIC) {
            hak_free_route_log("tiny_c7_registry", ptr);
            hak_tiny_free(ptr);
            goto done;
        }
    }

    // Raw header dispatch（mmap/malloc/BigCacheなど）
    {
        void* raw = (char*)ptr - HEADER_SIZE;

        // Phase 3 (2025-11-29): mincore() completely removed
        //
        // History:
        // - Phase 9: Originally used mincore() syscall to verify memory accessibility
        // - 2025-11-14: Added DISABLE_MINCORE flag for performance (+10.3% improvement)
        // - Phase 1b/2: Registry-based validation provides sufficient safety
        // - Phase 3: Dead code removal - mincore no longer needed
        //
        // Safety: Trust internal metadata (registry/headers/FrontGate classification)
        // - SuperSlab registry validates all Tiny allocations (Phase 1b/2)
        // - Headers validate Mid/Large allocations
        // - FrontGate classifier routes external allocations correctly
        int is_mapped = 1;

        if (!is_mapped) {
            // Memory not accessible, ptr likely has no header
            hak_free_route_log("unmapped_header_fallback", ptr);
            // Always punt to libc; never route unmapped/unknown pointers to Tiny
            extern void __libc_free(void*);
            ptr_trace_dump_now("free_api_libc_invalid_hdr");
            __libc_free(ptr);
            goto done;
        }

        // Safe to dereference header now
        AllocHeader* hdr = (AllocHeader*)raw;
        if (hdr->magic != HAKMEM_MAGIC) {
            // CRITICAL FIX (2025-11-07): Invalid magic could mean:
            // 1. Tiny allocation where SuperSlab lookup failed (NO header exists)
            // 2. Libc allocation from mixed environment
            // 3. Double-free or corrupted pointer

            if (g_invalid_free_log) fprintf(stderr, "[hakmem] ERROR: Invalid magic 0x%X (expected 0x%X)\n", hdr->magic, HAKMEM_MAGIC);

            // One-shot request-trace to help diagnose SS registry lookups
            hak_super_reg_reqtrace_dump(ptr);

            // Fail-fast diagnostics: never hand bad headers to Tiny or libc silently
            SuperSlab* ss_diag = hak_super_lookup(ptr);
            int slab_diag = ss_diag ? slab_index_for(ss_diag, ptr) : -1;
            fprintf(stderr,
                    "[INVALID_MAGIC_FREE] ptr=%p magic=0x%X mode=%d ss=%p slab=%d\n",
                    ptr, hdr->magic, g_invalid_free_mode, (void*)ss_diag, slab_diag);
            tiny_guard_on_invalid(ptr, hdr->magic);

            // If this pointer was a misclassified Tiny header miss, punt to libc to avoid corrupting TLS
            if (fg_misclass) {
                fprintf(stderr, "[FREE_MISCLASS_SKIP] ptr=%p hdr=0x%x (ignored to avoid corruption)\n",
                        ptr, hdr->magic);
                goto done;  // leak-safe skip: not our allocation
            }

            // Never route invalid headers into Tiny; fail-fast by default
            if (g_invalid_free_mode) {
                static int leak_warn = 0;
                if (!leak_warn) {
                    fprintf(stderr, "[hakmem] WARNING: Skipping free of invalid pointer %p (may leak memory)\n", ptr);
                    leak_warn = 1;
                }
                abort();
            } else {
                ptr_trace_dump_now("free_api_invalid_magic_failfast");
                abort();
            }
        }
        // Phase 5-Step3: Use Mid/Large Config Box (compile-time constant in PGO mode)
        if (MID_LARGE_BIGCACHE_ENABLED && hdr->class_bytes >= 2097152) {
            if (hak_bigcache_put(ptr, hdr->size, hdr->alloc_site)) goto done;
        }
        {
            static int g_bc_l25_en_free = -1; if (g_bc_l25_en_free == -1) { const char* e = getenv("HAKMEM_BIGCACHE_L25"); g_bc_l25_en_free = (e && atoi(e) != 0) ? 1 : 0; }
            if (g_bc_l25_en_free && MID_LARGE_BIGCACHE_ENABLED && hdr->size >= 524288 && hdr->size < 2097152) {
                if (hak_bigcache_put(ptr, hdr->size, hdr->alloc_site)) goto done;
            }
        }
        switch (hdr->method) {
            case ALLOC_METHOD_POOL: if (HAK_ENABLED_ALLOC(HAKMEM_FEATURE_POOL)) { hkm_ace_stat_mid_free(); hak_pool_free(ptr, hdr->size, hdr->alloc_site); goto done; } break;
            case ALLOC_METHOD_L25_POOL: hkm_ace_stat_large_free(); hak_l25_pool_free(ptr, hdr->size, hdr->alloc_site); goto done;
            case ALLOC_METHOD_MALLOC:
                // CRITICAL FIX: raw was allocated with __libc_malloc, so free with __libc_free
                // Using free(raw) would go through wrapper → infinite recursion
                hak_free_route_log("malloc_hdr", ptr);
                extern void __libc_free(void*);
                ptr_trace_dump_now("free_api_libc_malloc_hdr");
                fprintf(stderr, "[FREE_LIBC_HDR] raw=%p user=%p size=%zu method=%d magic=0x%X\n",
                        raw, ptr, hdr->size, (int)hdr->method, hdr->magic);
                __libc_free(raw);
                break;
            case ALLOC_METHOD_MMAP:
#ifdef __linux__
                if (HAK_ENABLED_MEMORY(HAKMEM_FEATURE_BATCH_MADVISE) && hdr->size >= BATCH_MIN_SIZE) { hak_batch_add(raw, hdr->size); goto done; }
                if (hkm_whale_put(raw, hdr->size) != 0) { hkm_sys_munmap(raw, hdr->size); }
#else
                // CRITICAL FIX: Same as ALLOC_METHOD_MALLOC
                extern void __libc_free(void*);
                ptr_trace_dump_now("free_api_libc_mmap_other");
                __libc_free(raw);
#endif
                break;
            default: HAKMEM_LOG("ERROR: Unknown allocation method: %d\n", hdr->method); break;
        }
    }

done:
#if HAKMEM_DEBUG_TIMING
    HKM_TIME_END(HKM_CAT_HAK_FREE, t0);
#endif
    return;
}

#endif // HAK_FREE_API_INC_H