// smallobject_policy_v7.c - Policy Box implementation

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "box/smallobject_policy_v7_box.h"

#ifndef likely
#define likely(x)   __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)
#endif

// ============================================================================
// TLS Policy Snapshot
// ============================================================================

static __thread SmallPolicyV7 g_small_policy_v7;
static __thread int g_small_policy_v7_init = 0;

const SmallPolicyV7* small_policy_v7_snapshot(void) {
    if (unlikely(!g_small_policy_v7_init)) {
        small_policy_v7_init_from_env(&g_small_policy_v7);
        g_small_policy_v7_init = 1;
    }
    return &g_small_policy_v7;
}

// ============================================================================
// ENV Helpers
// ============================================================================

static inline bool env_enabled(const char* name) {
    const char* e = getenv(name);
    return (e && *e && *e != '0');
}

static inline uint32_t env_class_mask(const char* name, uint32_t default_mask) {
    const char* e = getenv(name);
    if (e && *e) {
        return (uint32_t)strtoul(e, NULL, 0);
    }
    return default_mask;
}

// ============================================================================
// Policy Initialization from ENV
// ============================================================================

void small_policy_v7_init_from_env(SmallPolicyV7* policy) {
    if (!policy) return;

    // Default: all classes go to LEGACY
    for (int i = 0; i < 8; i++) {
        policy->route_kind[i] = SMALL_ROUTE_LEGACY;
    }

    // Priority 3: MID_v3 (257-768B, C5-C6 range)
    // ENV: HAKMEM_MID_V3_ENABLED, HAKMEM_MID_V3_CLASSES
    if (env_enabled("HAKMEM_MID_V3_ENABLED")) {
        uint32_t mid_mask = env_class_mask("HAKMEM_MID_V3_CLASSES", 0x60); // C5-C6 default
        for (int i = 0; i < 8; i++) {
            if (mid_mask & (1u << i)) {
                policy->route_kind[i] = SMALL_ROUTE_MID_V3;
            }
        }
    }

    // Priority 2: SmallObject v7 (research box, C6-only for now)
    // ENV: HAKMEM_SMALL_HEAP_V7_ENABLED, HAKMEM_SMALL_HEAP_V7_CLASSES
    if (env_enabled("HAKMEM_SMALL_HEAP_V7_ENABLED")) {
        uint32_t v7_mask = env_class_mask("HAKMEM_SMALL_HEAP_V7_CLASSES", 0x40); // C6 default
        for (int i = 0; i < 8; i++) {
            if (v7_mask & (1u << i)) {
                policy->route_kind[i] = SMALL_ROUTE_V7;
            }
        }
    }

    // Priority 1: ULTRA (highest priority, C4-C7)
    // ENV: HAKMEM_TINY_C7_ULTRA_ENABLED (C7), HAKMEM_TINY_C6_ULTRA_FREE_ENABLED (C6), etc.
    // Note: For now, we check individual ULTRA ENV vars

    // C7 ULTRA (default ON)
    if (env_enabled("HAKMEM_TINY_C7_ULTRA_ENABLED")) {
        policy->route_kind[7] = SMALL_ROUTE_ULTRA;
    }

    // C6 ULTRA (if C6 ULTRA free is enabled, route to ULTRA)
    // Note: This is a free-only optimization, not full ULTRA for C6 yet
    // Keep C6 routing as-is (v7 or MID_v3) for now

    // C4-C5 ULTRA (if enabled via ENV)
    // TODO: Add HAKMEM_TINY_C4_ULTRA_ENABLED / C5 when implemented

    // Debug output (if needed)
    static int g_debug_once = 0;
    if (!g_debug_once) {
        g_debug_once = 1;
        fprintf(stderr, "[POLICY_V7_INIT] Route assignments:\n");
        for (int i = 0; i < 8; i++) {
            fprintf(stderr, "  C%d: %s\n", i, small_route_kind_name(policy->route_kind[i]));
        }
    }
}

// ============================================================================
// Utility
// ============================================================================

const char* small_route_kind_name(SmallRouteKind kind) {
    switch (kind) {
        case SMALL_ROUTE_ULTRA:   return "ULTRA";
        case SMALL_ROUTE_V7:      return "V7";
        case SMALL_ROUTE_MID_V3:  return "MID_V3";
        case SMALL_ROUTE_LEGACY:  return "LEGACY";
        default:                  return "UNKNOWN";
    }
}