/**
 * libasos.c
 * مكتبة المستخدم ASOS - التنفيذ
 * ASOS Userspace Library - Implementation
 *
 * Userspace wrapper around ASOS syscall 450.
 * Handles intent construction, trust nonce generation,
 * and result parsing.
 *
 * Author: Ahmad Ali Parr
 * License: Sovereign Source
 */

#include "libasos.h"
#include "../kernel-module/intent_schema.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <sys/syscall.h>

/* Syscall number (custom) */
#define __NR_submit_system_intent 450

/* ═══════════════════════════════════════════════════════════════
 * Intent Handle | معالج النية
 * ═══════════════════════════════════════════════════════════════ */

struct asos_intent {
    struct SystemIntent raw;  /* Kernel structure */
    void *payload_copy;       /* Owned payload buffer */
};

struct asos_result {
    struct IntentResult raw;  /* Kernel result structure */
};

/* ═══════════════════════════════════════════════════════════════
 * Trust Nonce Generation | توليد nonce الثقة
 * ═══════════════════════════════════════════════════════════════ */

/**
 * generate_trust_nonce - Generate Blake3 trust nonce
 * @intent: Intent structure (partially filled)
 * @nonce_out: Output buffer (32 bytes)
 *
 * For Phase 4, this is a simplified hash. Phase 5 will use
 * proper Blake3 library (libblake3).
 */
static void generate_trust_nonce(const struct SystemIntent *intent,
                                  uint8_t *nonce_out)
{
    /* Simple hash for Phase 4: XOR of intent fields
     * Phase 5 will replace with real Blake3 implementation
     */
    uint32_t hash = 0;
    hash ^= intent->intent_type;
    hash ^= intent->priority;
    hash ^= (uint32_t)(intent->timestamp_ns & 0xFFFFFFFF);
    hash ^= (uint32_t)(intent->timestamp_ns >> 32);

    /* Hash goal_schema bytes */
    for (size_t i = 0; i < strlen(intent->goal_schema); i++) {
        hash ^= intent->goal_schema[i] << ((i % 4) * 8);
    }

    /* Fill nonce buffer with hash pattern */
    for (int i = 0; i < 32; i++) {
        nonce_out[i] = (hash >> ((i % 4) * 8)) & 0xFF;
    }
}

/* ═══════════════════════════════════════════════════════════════
 * Intent Builder | بناء النوايا
 * ═══════════════════════════════════════════════════════════════ */

asos_intent_t *asos_intent_new(asos_intent_type_t type,
                                asos_priority_t priority)
{
    asos_intent_t *intent = calloc(1, sizeof(asos_intent_t));
    if (!intent)
        return NULL;

    intent->raw.intent_type = (uint32_t)type;
    intent->raw.priority = (uint32_t)priority;
    intent->raw.flags = 0;
    intent->raw.payload_len = 0;
    intent->raw.payload_data = NULL;
    intent->payload_copy = NULL;

    /* Timestamp (monotonic clock) */
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC, &ts);
    intent->raw.timestamp_ns = (uint64_t)ts.tv_sec * 1000000000ULL +
                               (uint64_t)ts.tv_nsec;

    return intent;
}

int asos_intent_set_goal(asos_intent_t *intent, const char *goal)
{
    if (!intent || !goal)
        return -1;

    size_t len = strlen(goal);
    if (len >= MAX_GOAL_SCHEMA)
        return -1;

    strncpy(intent->raw.goal_schema, goal, MAX_GOAL_SCHEMA - 1);
    intent->raw.goal_schema[MAX_GOAL_SCHEMA - 1] = '\0';

    return 0;
}

int asos_intent_set_payload(asos_intent_t *intent,
                             const void *data, size_t len)
{
    if (!intent || !data || len > MAX_INTENT_PAYLOAD)
        return -1;

    /* Allocate payload copy */
    if (intent->payload_copy)
        free(intent->payload_copy);

    intent->payload_copy = malloc(len);
    if (!intent->payload_copy)
        return -1;

    memcpy(intent->payload_copy, data, len);
    intent->raw.payload_data = intent->payload_copy;
    intent->raw.payload_len = (uint32_t)len;

    return 0;
}

void asos_intent_free(asos_intent_t *intent)
{
    if (!intent)
        return;

    if (intent->payload_copy)
        free(intent->payload_copy);

    free(intent);
}

/* ═══════════════════════════════════════════════════════════════
 * Intent Submission | تقديم النوايا
 * ═══════════════════════════════════════════════════════════════ */

asos_result_t *asos_submit_intent(asos_intent_t *intent)
{
    if (!intent)
        return NULL;

    /* Generate trust nonce */
    generate_trust_nonce(&intent->raw, intent->raw.trust_nonce);

    /* Invoke syscall 450 */
    long ret = syscall(__NR_submit_system_intent, &intent->raw);
    if (ret < 0) {
        fprintf(stderr, "asos_submit_intent: syscall failed, errno=%ld\n", ret);
        return NULL;
    }

    /* TODO Phase 4: Wait for result from ring buffer
     *
     * For now, create stub result (kernel doesn't implement result yet)
     */
    asos_result_t *result = calloc(1, sizeof(asos_result_t));
    if (!result)
        return NULL;

    result->raw.status = 0;  /* Success stub */
    result->raw.kar_action = intent->raw.intent_type;
    result->raw.resource_handle = 0;
    result->raw.bytes_transferred = intent->raw.payload_len;
    result->raw.execution_time_ns = 1000000;  /* 1ms stub */
    result->raw.kar_agent_id = 0;

    /* Stub WORM seal */
    memcpy(result->raw.worm_seal, intent->raw.trust_nonce, TRUST_NONCE_SIZE);

    return result;
}

int asos_submit_intent_async(asos_intent_t *intent,
                              asos_callback_t callback,
                              void *user_data)
{
    /* TODO Phase 4: Implement async submission with pthread */
    (void)intent;
    (void)callback;
    (void)user_data;
    return -1;  /* Not implemented yet */
}

/* ═══════════════════════════════════════════════════════════════
 * Result Inspection | فحص النتائج
 * ═══════════════════════════════════════════════════════════════ */

int asos_result_status(const asos_result_t *result)
{
    if (!result)
        return ASOS_EINVALID_INTENT;
    return result->raw.status;
}

size_t asos_result_bytes_transferred(const asos_result_t *result)
{
    if (!result)
        return 0;
    return result->raw.bytes_transferred;
}

uint64_t asos_result_execution_time_ns(const asos_result_t *result)
{
    if (!result)
        return 0;
    return result->raw.execution_time_ns;
}

int asos_result_worm_seal(const asos_result_t *result, uint8_t *seal_out)
{
    if (!result || !seal_out)
        return -1;

    memcpy(seal_out, result->raw.worm_seal, TRUST_NONCE_SIZE);
    return 0;
}

void asos_result_free(asos_result_t *result)
{
    if (result)
        free(result);
}

/* ═══════════════════════════════════════════════════════════════
 * Error Strings | سلاسل الأخطاء
 * ═══════════════════════════════════════════════════════════════ */

const char *asos_strerror(int errnum)
{
    switch (errnum) {
        case ASOS_EINVALID_INTENT:
            return "Invalid intent structure";
        case ASOS_ETRUST_NONCE_FAIL:
            return "Trust nonce validation failed";
        case ASOS_EKAR_POLICY_REJECT:
            return "Policy engine rejected intent";
        case ASOS_EKAR_NO_AGENT:
            return "No suitable agent available";
        case ASOS_EKAR_TIMEOUT:
            return "Intent processing timeout";
        case ASOS_EWORM_SEAL_FAIL:
            return "Failed to generate WORM seal";
        default:
            return "Unknown error";
    }
}

/* ═══════════════════════════════════════════════════════════════
 * Library Init/Cleanup | تهيئة/تنظيف المكتبة
 * ═══════════════════════════════════════════════════════════════ */

int asos_init(void)
{
    /* TODO: Initialize any global state (e.g., ring buffer mmap) */
    return 0;
}

void asos_cleanup(void)
{
    /* TODO: Cleanup global state */
}