/*
 * instance_lite.c — lightweight uTun instance lifecycle for Android
 *
 * Kotlin sends INI config text → parse_config_from_buf →
 * utun_instance_create_from_config → sqlite3_open → utun_instance_init →
 * pthread with uasync_poll loop.
 *
 * Mirrors UtunNode::runLoop() from tools/chatgui/transport/utun_node.cpp:221-372.
 */
#include "instance_lite.h"
#include "utun_instance.h"
#include "config_parser.h"
#include "config_updater.h"
#include "secure_channel.h"
#include "etcp_router.h"
#include "topo_node_sqlite.h"
#include "chat/chat_core.h"
#include "chat/chat_sync.h"
#include "chat/chat_event.h"
#include "u_async.h"
#include "sqlite3.h"
#include "mem.h"
#include "debug_config.h"
#include "../jni_bridge/android_udp_log.h"
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <openssl/evp.h>

#ifdef __ANDROID__
#include <android/log.h>
#define  IL_LOGV(fmt, ...)  __android_log_print(ANDROID_LOG_VERBOSE, "utun-inst", fmt, ##__VA_ARGS__)
#define  IL_LOGI(fmt, ...)  __android_log_print(ANDROID_LOG_INFO,    "utun-inst", fmt, ##__VA_ARGS__)
#define  IL_LOGE(fmt, ...)  __android_log_print(ANDROID_LOG_ERROR,   "utun-inst", fmt, ##__VA_ARGS__)
#else
#define  IL_LOGV(fmt, ...)  fprintf(stderr, fmt "\n", ##__VA_ARGS__)
#define  IL_LOGI(fmt, ...)  fprintf(stderr, fmt "\n", ##__VA_ARGS__)
#define  IL_LOGE(fmt, ...)  fprintf(stderr, fmt "\n", ##__VA_ARGS__)
#endif

/* ── Static state ── */

static struct UASYNC*        g_ua = NULL;
static     struct UTUN_INSTANCE* g_inst = NULL;
static pthread_t             g_thread;
static volatile int          g_running = 0;
static volatile int          g_stop = 0;
static char                  g_db_path[512];
static instance_lite_event_fn g_event_handler = NULL;
static char g_generated_pub[65];
static char g_generated_priv[65];

/* ── Generate X25519 key pair, hex-encode to out buffers ── */

static int generate_x25519_keys(char pub_hex[65], char priv_hex[65]) {
    EVP_PKEY* pkey = NULL;
    EVP_PKEY_CTX* ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_X25519, NULL);
    if (!ctx) return -1;
    if (EVP_PKEY_keygen_init(ctx) <= 0 || EVP_PKEY_generate(ctx, &pkey) <= 0) {
        EVP_PKEY_CTX_free(ctx);
        return -1;
    }
    EVP_PKEY_CTX_free(ctx);
    size_t pkLen = 32, skLen = 32;
    uint8_t pk[32], sk[32];
    EVP_PKEY_get_raw_public_key(pkey, pk, &pkLen);
    EVP_PKEY_get_raw_private_key(pkey, sk, &skLen);
    EVP_PKEY_free(pkey);
    for (int i = 0; i < 32; i++) snprintf(pub_hex + i * 2, 3, "%02x", pk[i]);
    for (int i = 0; i < 32; i++) snprintf(priv_hex + i * 2, 3, "%02x", sk[i]);
    pub_hex[64] = '\0';
    priv_hex[64] = '\0';
    return 0;
}

static void save_keys_to_file(const char* pub, const char* priv) {
    if (!g_db_path[0]) { IL_LOGE("save_keys_to_file: g_db_path is empty, keys not saved to disk"); return; }
    char fname[512];
    snprintf(fname, sizeof(fname), "%s/keys.conf", g_db_path);
    FILE* f = fopen(fname, "w");
    if (!f) { IL_LOGE("cannot write %s: %s", fname, strerror(errno)); return; }
    fchmod(fileno(f), 0600);
    fprintf(f, "public_key=%s\nprivate_key=%s\n", pub, priv);
    fclose(f);
    IL_LOGI("keys saved to %s", fname);
}

/* ── Ensure valid keys in config, generate if missing ── */

static void ensure_keys(struct utun_config* config) {
    if (strlen(config->global.my_private_key_hex) != 64 ||
        strlen(config->global.my_public_key_hex) != 64) {
        IL_LOGI("config keys missing or invalid, generating new X25519 keypair");
        if (generate_x25519_keys(g_generated_pub, g_generated_priv) == 0) {
            memcpy(config->global.my_public_key_hex, g_generated_pub, 65);
            memcpy(config->global.my_private_key_hex, g_generated_priv, 65);
            IL_LOGI("new keys generated pub=%s", g_generated_pub);
            save_keys_to_file(g_generated_pub, g_generated_priv);
        } else {
            IL_LOGE("key generation failed");
        }
    }
}

/* ── Helper: extract single config value by key ── */

static const char* cfg_get(const char* text, const char* key) {
    size_t klen = strlen(key);
    const char* p = text;
    while (*p) {
        if (strncmp(p, key, klen) == 0 && p[klen] == '=') {
            return p + klen + 1;
        }
        while (*p && *p != '\n') p++;
        if (*p == '\n') p++;
    }
    return NULL;
}

static void cfg_get_val(const char* text, const char* key, char* out, size_t out_sz) {
    const char* v = cfg_get(text, key);
    if (!v) { out[0] = '\0'; return; }
    size_t i = 0;
    while (*v && *v != '\n' && *v != '\r' && i < out_sz - 1)
        out[i++] = *v++;
    out[i] = '\0';
}

/* ── Chat event forward → Kotlin callback ── */

static void chat_event_forward(int type, const uint8_t* data, int len) {
    if (g_event_handler) g_event_handler(type, data, len);
}

static void nodeinfo_event_cb(struct TOPO_GROUP* group, struct TOPO_GROUP_NODE* nq, void* arg) {
    (void)group; (void)arg;
    if (!nq || !g_event_handler) return;
    uint16_t best_rtt = node_best_rtt(nq);
    uint8_t data[12];
    memcpy(data, &nq->node_id, 8);
    data[8] = nq->conn_presence;
    data[9] = nq->conn_up;
    memcpy(data + 10, &best_rtt, 2);
    g_event_handler(CHAT_EVT_NODEINFO_UPDATED, data, sizeof(data));
}

/* ── Thread function ── */

static void* instance_thread(void* arg) {
    char* config_text = (char*)arg;

    struct utun_config* config = parse_config_from_buf(config_text, strlen(config_text), "android");
    u_free(config_text);
    if (!config) { IL_LOGE("parse_config_from_buf failed"); return NULL; }

    g_ua = uasync_create();
    if (!g_ua) { IL_LOGE("uasync_create failed"); free_config(config); return NULL; }

    if (config->global.log_udp_ip[0] && config->global.log_udp_port > 0) {
        udp_log_set_target(config->global.log_udp_ip, config->global.log_udp_port);
        uasync_set_timeout(g_ua, 2000, NULL, udp_trampoline, "udp_log_flush");
    }

    chat_event_set_handler(chat_event_forward);
    ensure_keys(config);

    g_inst = utun_instance_create_from_config(g_ua, config);
    if (!g_inst) {
        IL_LOGE("utun_instance_create_from_config failed");
        uasync_destroy(g_ua, 0);
        g_ua = NULL;
        u_report_unfreed_blocks();
        return NULL;
    }

    IL_LOGI("instance created, node_id=0x%016llx", (unsigned long long)g_inst->node_id);

    /* Open shared SQLite DB */
    if (g_db_path[0] && !g_inst->topo_sqlite_db) {
        char db_file[512];
        snprintf(db_file, sizeof(db_file), "%s/chats.db", g_db_path);
        int rc = sqlite3_open_v2(db_file, &g_inst->topo_sqlite_db,
            SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_FULLMUTEX, NULL);
        if (rc == SQLITE_OK && g_inst->topo_sqlite_db) {
            sqlite3_exec(g_inst->topo_sqlite_db, "PRAGMA journal_mode=WAL", NULL, NULL, NULL);
            sqlite3_exec(g_inst->topo_sqlite_db, "PRAGMA foreign_keys=ON", NULL, NULL, NULL);
            sqlite3_exec(g_inst->topo_sqlite_db, "PRAGMA synchronous=NORMAL", NULL, NULL, NULL);
            sqlite3_exec(g_inst->topo_sqlite_db, "PRAGMA wal_autocheckpoint=10000", NULL, NULL, NULL);
            topo_node_sqlite_init(g_inst->topo_sqlite_db);
            IL_LOGI("SQLite opened %s", db_file);
        } else {
            IL_LOGE("SQLite open failed rc=%d", rc);
            if (g_inst->topo_sqlite_db) { sqlite3_close(g_inst->topo_sqlite_db); g_inst->topo_sqlite_db = NULL; }
        }
    }

    /* Full init: db_sync, chat_core, chat_sync, init_connections */
    if (utun_instance_init(g_inst) != 0) {
        IL_LOGE("utun_instance_init failed");
        utun_instance_destroy(g_inst);
        g_inst = NULL;
        uasync_destroy(g_ua, 0);
        g_ua = NULL;
        u_report_unfreed_blocks();
        return NULL;
    }

    /* Bind chat sync via etcp_router */
    etcp_router_bind(g_inst, ETCP_RT_ID_CHAT_SYNC, NULL);

    utun_add_nodeinfo_cbk(g_inst, nodeinfo_event_cb, NULL);

    /* Set my_name from config */
    if (g_inst->config->global.name[0]) {
        chat_core_update_my_name(g_inst->config->global.name);
        IL_LOGI("my_name set to '%s'", g_inst->config->global.name);
    }

    IL_LOGI("all init done, entering poll loop");

    /* Notify GUI of current public key (initial generation or existing) */
    if (strlen(config->global.my_public_key_hex) == 64) {
        chat_event_post(CHAT_EVT_KEYS_GENERATED,
                        (const uint8_t*)config->global.my_public_key_hex, 64);
    }

    g_running = 1;
    chat_event_post(CHAT_EVT_SERVICE_STARTED, NULL, 0);

    while (!g_stop) {
        uasync_poll(g_ua, 100);
    }

    IL_LOGI("poll loop exit, cleaning up");

    if (g_inst) {
        utun_instance_destroy(g_inst);
        g_inst = NULL;
    }
    if (g_ua) {
        uasync_destroy(g_ua, 0);
        g_ua = NULL;
    }
    u_report_unfreed_blocks();
    chat_event_post(CHAT_EVT_SERVICE_STOPPED, NULL, 0);
    g_event_handler = NULL;
    pthread_detach(pthread_self());
    IL_LOGI("cleanup complete");
    return NULL;
}

/* ── Public API ── */

int instance_lite_start(const char* config_text) {
    if (!config_text) return -1;
    if (g_inst) return 0;

    debug_config_init();
    debug_set_level(DEBUG_LEVEL_INFO);
    debug_enable_function_name(0);

    cfg_get_val(config_text, "db_path", g_db_path, sizeof(g_db_path));

    char* config_copy = u_strdup(config_text);
    if (!config_copy) return -1;

    g_stop = 0;
    int rc = pthread_create(&g_thread, NULL, instance_thread, config_copy);
    if (rc != 0) {
        u_free(config_copy);
        IL_LOGE("pthread_create failed rc=%d", rc);
        return -1;
    }

    IL_LOGI("started OK");
    return 0;
}

void instance_lite_stop(void) {
    if (!g_inst) return;
    IL_LOGI("stopping...");
    g_stop = 1;
    if (g_ua) uasync_wakeup(g_ua);
    for (int i = 0; i < 500 && g_inst != NULL; i++) usleep(10000);
    if (g_inst) {
        IL_LOGE("stop timeout, force cleanup");
        g_inst = NULL;
        g_ua = NULL;
    }
    g_running = 0;
}

static void restart_trampoline(void* arg) {
    char* config_text = (char*)arg;
    IL_LOGI("restart: begin");

    chat_sync_destroy(g_inst);
    chat_core_destroy(g_inst);

    if (g_inst->topo_sqlite_db) {
        sqlite3_close(g_inst->topo_sqlite_db);
        g_inst->topo_sqlite_db = NULL;
    }

    struct utun_config* new_config = parse_config_from_buf(config_text, strlen(config_text), "android");
    u_free(config_text);
    if (!new_config) {
        IL_LOGE("restart: parse_config failed");
        g_running = 0;
        return;
    }

    free_config(g_inst->config);
    g_inst->config = new_config;

    ensure_keys(new_config);

    uint8_t pk_bin[32];
    for (int i = 0; i < 32; i++) { unsigned int b; sscanf(new_config->global.my_public_key_hex + i * 2, "%2x", &b); pk_bin[i] = (uint8_t)b; }
    g_inst->node_id = sc_derive_node_id_from_pubkey(pk_bin);
    sc_init_local_keys(&g_inst->my_keys, new_config->global.my_public_key_hex, new_config->global.my_private_key_hex);

    if (new_config->global.log_udp_ip[0] && new_config->global.log_udp_port > 0) {
        udp_log_set_target(new_config->global.log_udp_ip, new_config->global.log_udp_port);
        uasync_set_timeout(g_ua, 2000, NULL, udp_trampoline, "udp_log_flush");
    } else {
        udp_log_stop();
    }

    char db_file[512];
    snprintf(db_file, sizeof(db_file), "%s/chats.db", g_db_path);
    int rc = sqlite3_open_v2(db_file, &g_inst->topo_sqlite_db,
        SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_FULLMUTEX, NULL);
    if (rc == SQLITE_OK && g_inst->topo_sqlite_db) {
        sqlite3_exec(g_inst->topo_sqlite_db, "PRAGMA journal_mode=WAL", NULL, NULL, NULL);
        sqlite3_exec(g_inst->topo_sqlite_db, "PRAGMA foreign_keys=ON", NULL, NULL, NULL);
        sqlite3_exec(g_inst->topo_sqlite_db, "PRAGMA synchronous=NORMAL", NULL, NULL, NULL);
        topo_node_sqlite_init(g_inst->topo_sqlite_db);
        IL_LOGI("restart: SQLite reopened %s", db_file);
    } else {
        IL_LOGE("restart: SQLite reopen failed rc=%d", rc);
        g_running = 0;
        return;
    }

    if (utun_instance_init(g_inst) != 0) {
        IL_LOGE("restart: utun_instance_init failed");
        g_running = 0;
        return;
    }

    if (g_inst->config->global.name[0]) {
        chat_core_update_my_name(g_inst->config->global.name);
        IL_LOGI("restart: my_name set to '%s'", g_inst->config->global.name);
    }

    IL_LOGI("restart: done");
}

void instance_lite_restart(const char* new_config_text) {
    if (!g_ua || !g_inst || !new_config_text) return;
    IL_LOGI("restart: posting to uasync");
    char* copy = u_strdup(new_config_text);
    if (!copy) return;
    uasync_post(g_ua, restart_trampoline, copy);
}

/* ── Health check ping ── */

static volatile int g_ping_id = 0;
static volatile int g_pong_id = 0;

static void ping_trampoline(void* arg) {
    (void)arg;
    g_pong_id = g_ping_id;
}

void instance_lite_ping(void) {
    if (!g_ua || !g_inst) return;
    g_ping_id++;
    uasync_post(g_ua, ping_trampoline, NULL);
}

int instance_lite_is_responsive(void) {
    return (g_pong_id == g_ping_id) ? 1 : 0;
}

int instance_lite_is_running(void) {
    return g_inst != NULL ? 1 : 0;
}

struct UASYNC* instance_lite_get_uasync(void) {
    return g_ua;
}

static void regenerate_trampoline(void* arg) {
    (void)arg;
    if (!g_inst || !g_inst->config) { IL_LOGE("regenerate_keys: instance not running"); return; }
    struct utun_config* config = g_inst->config;
    IL_LOGI("regenerating keys...");
    config->global.my_public_key_hex[0] = '\0';
    config->global.my_private_key_hex[0] = '\0';
    ensure_keys(config);
    if (g_generated_pub[0]) {
        uint8_t pk_bin[32];
        for (int i = 0; i < 32; i++) { unsigned int b; sscanf(g_generated_pub + i * 2, "%2x", &b); pk_bin[i] = (uint8_t)b; }
        g_inst->node_id = sc_derive_node_id_from_pubkey(pk_bin);
        sc_init_local_keys(&g_inst->my_keys, g_generated_pub, g_generated_priv);
        IL_LOGI("keys regenerated, node_id=0x%016llx", (unsigned long long)g_inst->node_id);
        chat_event_post(CHAT_EVT_KEYS_GENERATED, (const uint8_t*)g_generated_pub, 64);
    }
}

void instance_lite_regenerate_keys(void) {
    if (!g_ua || !g_inst) return;
    uasync_post(g_ua, regenerate_trampoline, NULL);
}

void instance_lite_set_event_handler(instance_lite_event_fn handler) {
    g_event_handler = handler;
    if (g_running) chat_event_set_handler(chat_event_forward);
}