/**
 * @file etcp_api.c
 * @brief ETCP API — send/bind/recv dispatch
 */
#include "etcp_api.h"
#include "etcp.h"
#include "pkt_normalizer.h"
#include "utun_instance.h"
#include "../lib/debug_config.h"
#include "../lib/mem.h"
#include <string.h>

#define DEBUG_CATEGORY_ETCP_API DEBUG_CATEGORY_ETCP

static void etcp_cbk_add_to_chain(struct etcp_cbk_entry** head, etcp_cbk_fn fn, void* arg) {
    if (!head || !fn) return;
    struct etcp_cbk_entry* e = u_malloc(sizeof(struct etcp_cbk_entry));
    if (!e) return;
    e->fn = fn; e->arg = arg; e->next = *head;
    *head = e;
}
static void etcp_cbk_remove_from_chain(struct etcp_cbk_entry** head, etcp_cbk_fn fn, void* arg) {
    if (!head || !fn) return;
    struct etcp_cbk_entry** p = head;
    while (*p) {
        if ((*p)->fn == fn && (*p)->arg == arg) {
            struct etcp_cbk_entry* rm = *p;
            *p = rm->next; u_free(rm); return;
        }
        p = &(*p)->next;
    }
}

void etcp_conn_add_init_cbk(struct ETCP_CONN* conn, etcp_cbk_fn fn, void* arg) { if (conn) etcp_cbk_add_to_chain(&conn->init_cbks, fn, arg); }
void etcp_conn_remove_init_cbk(struct ETCP_CONN* conn, etcp_cbk_fn fn, void* arg) { if (conn) etcp_cbk_remove_from_chain(&conn->init_cbks, fn, arg); }
void etcp_conn_add_up_cbk(struct ETCP_CONN* conn, etcp_cbk_fn fn, void* arg) { if (conn) etcp_cbk_add_to_chain(&conn->up_cbks, fn, arg); }
void etcp_conn_remove_up_cbk(struct ETCP_CONN* conn, etcp_cbk_fn fn, void* arg) { if (conn) etcp_cbk_remove_from_chain(&conn->up_cbks, fn, arg); }
void etcp_conn_add_down_cbk(struct ETCP_CONN* conn, etcp_cbk_fn fn, void* arg) { if (conn) etcp_cbk_add_to_chain(&conn->down_cbks, fn, arg); }
void etcp_conn_remove_down_cbk(struct ETCP_CONN* conn, etcp_cbk_fn fn, void* arg) { if (conn) etcp_cbk_remove_from_chain(&conn->down_cbks, fn, arg); }
void etcp_add_new_conn_cbk(struct UTUN_INSTANCE* inst, etcp_cbk_fn fn, void* arg) { if (inst) etcp_cbk_add_to_chain(&inst->new_conn_cbks, fn, arg); }
void etcp_remove_new_conn_cbk(struct UTUN_INSTANCE* inst, etcp_cbk_fn fn, void* arg) { if (inst) etcp_cbk_remove_from_chain(&inst->new_conn_cbks, fn, arg); }

static void etcp_status_cbk_add_chain(struct etcp_status_cbk_entry** head, etcp_conn_status_fn fn, void* arg) {
    if (!head || !fn) return;
    struct etcp_status_cbk_entry* e = u_malloc(sizeof(struct etcp_status_cbk_entry));
    if (!e) return;
    e->fn = fn; e->arg = arg; e->next = *head;
    *head = e;
}
static void etcp_status_cbk_remove_chain(struct etcp_status_cbk_entry** head, etcp_conn_status_fn fn, void* arg) {
    if (!head || !fn) return;
    struct etcp_status_cbk_entry** p = head;
    while (*p) {
        if ((*p)->fn == fn && (*p)->arg == arg) {
            struct etcp_status_cbk_entry* rm = *p;
            *p = rm->next; u_free(rm); return;
        }
        p = &(*p)->next;
    }
}
void etcp_add_conn_status_cbk(struct UTUN_INSTANCE* inst, etcp_conn_status_fn fn, void* arg) { if (inst) etcp_status_cbk_add_chain(&inst->conn_status_cbks, fn, arg); }
void etcp_remove_conn_status_cbk(struct UTUN_INSTANCE* inst, etcp_conn_status_fn fn, void* arg) { if (inst) etcp_status_cbk_remove_chain(&inst->conn_status_cbks, fn, arg); }
void etcp_set_routing_exchange_state(struct ETCP_CONN* conn, uint8_t new_state) {
    if (!conn) return;
    conn->routing_exchange_active = new_state;
    if (new_state >= 3 && conn->bgp_ready_cbk)
        conn->bgp_ready_cbk(conn);
}

int etcp_bind(struct UTUN_INSTANCE* inst, uint8_t id, etcp_recv_fn callback) {
    if (!inst || !callback || (unsigned)id >= ETCP_MAX_BINDINGS) return -1;
    inst->api_bindings.callbacks[id] = callback;
    return 0;
}

int etcp_unbind(struct UTUN_INSTANCE* inst, uint8_t id) {
    if (!inst || (unsigned)id >= ETCP_MAX_BINDINGS) return -1;
    inst->api_bindings.callbacks[id] = NULL;
    return 0;
}

int etcp_send(struct ETCP_CONN* conn, struct ll_entry* entry) {
    if (!conn || !entry || !conn->send_input_q) return -1;
    return queue_data_put(conn->send_input_q, entry);
}

void etcp_int_recv(struct ll_queue* queue, void* arg) {
    struct ETCP_CONN* conn = (struct ETCP_CONN*)arg;
    if (!queue || !conn) return;
    struct ll_entry* e = queue_data_get(queue);
    if (!e) { queue_resume_callback(queue); return; }
    if (!e->dgram || e->len == 0) { queue_dgram_free(e); queue_entry_free(e); queue_resume_callback(queue); return; }
    uint8_t id = e->dgram[0];
    struct UTUN_INSTANCE* inst = conn->instance;
    if (!inst) { queue_dgram_free(e); queue_entry_free(e); queue_resume_callback(queue); return; }
    if (inst->api_bindings.callbacks[id]) {
        DEBUG_TRACE(DEBUG_CATEGORY_DEBUG, "dispatch id=0x%02x conn=%s len=%zu", id, conn->log_name, e->len);
        inst->api_bindings.callbacks[id](conn, e);
    } else if (inst->api_bindings.callbacks[0]) {
        DEBUG_TRACE(DEBUG_CATEGORY_DEBUG, "dispatch id=0x%02x (fallback) conn=%s len=%zu", id, conn->log_name, e->len);
        inst->api_bindings.callbacks[0](conn, e);
    } else { DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "dispatch id=0x%02x NO CB conn=%s len=%zu — DROPPED", id, conn->log_name, e->len); queue_dgram_free(e); queue_entry_free(e); }
    queue_resume_callback(queue);
}