// tiny_c6_inline_slots_ifl.c - Phase 91: C6 Intrusive LIFO Inline Slots Implementation
//
// Goal: TLS variable definition, ENV refresh, overflow handler
// Scope: Per-thread LIFO state, initialization, drain to unified_cache

#include <stdlib.h>
#include <stdio.h>
#include "box/tiny_c6_inline_slots_ifl_env_box.h"
#include "box/tiny_c6_inline_slots_ifl_tls_box.h"
#include "box/tiny_unified_lifo_box.h"

// ============================================================================
// Global State (set by refresh function)
// ============================================================================

uint8_t g_tiny_c6_inline_slots_ifl_enabled = 0;
uint8_t g_tiny_c6_inline_slots_ifl_strict = 0;

// ============================================================================
// TLS Variable Definition
// ============================================================================

// TLS instance (one per thread)
// Zero-initialized by default (head=NULL, count=0, enabled=0)
__thread struct TinyC6InlineSlotsIFL g_tiny_c6_inline_slots_ifl = {
    .head = NULL,
    .count = 0,
    .enabled = 0,
};

// ============================================================================
// ENV Refresh (called from bench_profile.h::refresh_all_env_caches)
// ============================================================================

void tiny_c6_inline_slots_ifl_refresh_from_env(void) {
    // 1. Read master ENV gate
    const char* env_val = getenv("HAKMEM_TINY_C6_INLINE_SLOTS_IFL");
    int requested = (env_val && *env_val && *env_val != '0') ? 1 : 0;

    if (!requested) {
        g_tiny_c6_inline_slots_ifl_enabled = 0;
        return;
    }

    // 2. Fail-fast: LARSON_FIX incompatible
    //    Intrusive LIFO uses next pointer in freed object header,
    //    cannot coexist with owner_tid validation in header
    const char* larson_env = getenv("HAKMEM_TINY_LARSON_FIX");
    int larson_fix_enabled = (larson_env && *larson_env && *larson_env != '0') ? 1 : 0;

    if (larson_fix_enabled) {
#if !HAKMEM_BUILD_RELEASE
        fprintf(stderr, "[C6-IFL] FAIL-FAST: HAKMEM_TINY_LARSON_FIX=1 incompatible with intrusive LIFO, disabling\n");
        fflush(stderr);
#endif
        g_tiny_c6_inline_slots_ifl_enabled = 0;
        g_tiny_c6_inline_slots_ifl_strict = 1;
        return;
    }

    // 3. Read strict mode (diagnostic, not enforced)
    const char* strict_env = getenv("HAKMEM_TINY_C6_IFL_STRICT");
    g_tiny_c6_inline_slots_ifl_strict = (strict_env && *strict_env && *strict_env != '0') ? 1 : 0;

    // 4. Enable IFL for this thread
    g_tiny_c6_inline_slots_ifl_enabled = 1;
    g_tiny_c6_inline_slots_ifl.enabled = 1;

#if !HAKMEM_BUILD_RELEASE
    fprintf(stderr, "[C6-IFL] Initialized: enabled=1, strict=%d\n",
            g_tiny_c6_inline_slots_ifl_strict);
    fflush(stderr);
#endif
}

// ============================================================================
// Overflow Handler: Drain LIFO to Unified Cache
// ============================================================================

void tiny_c6_inline_slots_ifl_drain_to_unified(void) {
    // Drain all entries from LIFO head to unified_cache
    // Called when count > 128 (overflow condition)

    while (g_tiny_c6_inline_slots_ifl.count > 0) {
        void* ptr = tiny_c6_inline_slots_ifl_pop_fast();
        if (ptr == NULL) {
            break;  // Should not happen if count tracking is correct
        }

        // Push to unified_cache LIFO for C6
        int success = unified_cache_try_push_lifo(6, ptr);
        if (!success) {
            // Unified cache is full; this should be rare
            // For now, we leak the pointer (FIXME: proper fallback)
#if !HAKMEM_BUILD_RELEASE
            fprintf(stderr, "[C6-IFL-DRAIN] WARNING: unified_cache full, dropping pointer %p\n", ptr);
            fflush(stderr);
#endif
        }
    }
}