#include <string.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_system.h"
#include "esp_wifi.h"
#include "esp_event.h"
#include "esp_log.h"
#include "nvs_flash.h"
#include "nvs.h"
#include "wifi_manager.h"

static const char *TAG = "WIFI_MANAGER";

// FreeRTOS event group for WiFi events
static EventGroupHandle_t s_wifi_event_group;

// Current WiFi state
static wifi_state_t s_wifi_state = WIFI_STATE_DISCONNECTED;

// Retry counter
static int s_retry_num = 0;

// Event callback
static wifi_event_callback_t s_event_callback = NULL;

// Scan mode flag
static bool s_scan_mode = false;

// NVS namespace
#define NVS_NAMESPACE "wifi_creds"

static void wifi_event_handler(void* arg, esp_event_base_t event_base,
                              int32_t event_id, void* event_data)
{
    if (event_base == WIFI_EVENT) {
        switch (event_id) {
            case WIFI_EVENT_STA_START:
                if (!s_scan_mode) {  // Only connect if not in scan mode
                    esp_wifi_connect();
                    s_wifi_state = WIFI_STATE_CONNECTING;
                    if (s_event_callback) {
                        s_event_callback(s_wifi_state);
                    }
                }
                break;
                
            case WIFI_EVENT_STA_DISCONNECTED:
                if (event_data) {
                    wifi_event_sta_disconnected_t* disconnected = (wifi_event_sta_disconnected_t*) event_data;
                    ESP_LOGE(TAG, "Disconnect reason : %d", disconnected->reason);
                    switch(disconnected->reason) {
                        case WIFI_REASON_AUTH_EXPIRE:
                            ESP_LOGE(TAG, "Authentication expired");
                            break;
                        case WIFI_REASON_AUTH_FAIL:
                            ESP_LOGE(TAG, "Authentication failed");
                            break;
                        case WIFI_REASON_NO_AP_FOUND:
                            ESP_LOGE(TAG, "AP not found - check SSID");
                            break;
                        case WIFI_REASON_HANDSHAKE_TIMEOUT:
                            ESP_LOGE(TAG, "Handshake timeout - check password");
                            break;
                        default:
                            ESP_LOGE(TAG, "Other reason: %d", disconnected->reason);
                    }
                }
                if (s_retry_num < WIFI_MAXIMUM_RETRY) {
                    esp_wifi_connect();
                    s_retry_num++;
                    ESP_LOGI(TAG, "Retry connecting to AP (%d/%d)", s_retry_num, WIFI_MAXIMUM_RETRY);
                } else {
                    xEventGroupSetBits(s_wifi_event_group, WIFI_FAIL_BIT);
                    s_wifi_state = WIFI_STATE_ERROR;
                    ESP_LOGI(TAG, "Failed to connect to AP");
                }
                if (s_event_callback) {
                    s_event_callback(s_wifi_state);
                }
                break;
                
            default:
                break;
        }
    } else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
        ip_event_got_ip_t* event = (ip_event_got_ip_t*) event_data;
        ESP_LOGI(TAG, "Got IP: " IPSTR, IP2STR(&event->ip_info.ip));
        s_retry_num = 0;
        xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
        s_wifi_state = WIFI_STATE_CONNECTED;
        if (s_event_callback) {
            s_event_callback(s_wifi_state);
        }
    }
}

esp_err_t wifi_manager_init(void)
{
    esp_err_t ret = ESP_OK;
    
    // Initialize NVS
    ret = nvs_flash_init();
    if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
        ESP_ERROR_CHECK(nvs_flash_erase());
        ret = nvs_flash_init();
    }
    ESP_ERROR_CHECK(ret);
    
    // Create event group
    s_wifi_event_group = xEventGroupCreate();
    if (s_wifi_event_group == NULL) {
        ESP_LOGE(TAG, "Failed to create event group");
        return ESP_FAIL;
    }
    
    // Initialize TCP/IP stack
    ESP_ERROR_CHECK(esp_netif_init());
    ESP_ERROR_CHECK(esp_event_loop_create_default());
    esp_netif_create_default_wifi_sta();
    
    // Initialize WiFi with default config
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
    
    // Register event handlers
    ESP_ERROR_CHECK(esp_event_handler_instance_register(WIFI_EVENT,
                                                        ESP_EVENT_ANY_ID,
                                                        &wifi_event_handler,
                                                        NULL,
                                                        NULL));
    ESP_ERROR_CHECK(esp_event_handler_instance_register(IP_EVENT,
                                                        IP_EVENT_STA_GOT_IP,
                                                        &wifi_event_handler,
                                                        NULL,
                                                        NULL));
    
    // Set WiFi mode to station
    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
    
    // Disable power save mode to ensure WiFi works properly
    ESP_ERROR_CHECK(esp_wifi_set_ps(WIFI_PS_NONE));
    
    // Set WiFi country (important for proper channel scanning)
    wifi_country_t wifi_country = {
        .cc = "US",
        .schan = 1,
        .nchan = 11,
        .max_tx_power = 84,
        .policy = WIFI_COUNTRY_POLICY_AUTO,
    };
    ESP_ERROR_CHECK(esp_wifi_set_country(&wifi_country));
    
    ESP_LOGI(TAG, "WiFi manager initialized");
    return ESP_OK;
}

esp_err_t wifi_manager_start(void)
{
    char ssid[33] = {0};
    char password[65] = {0};
    
    // Try to get credentials from NVS
    if (wifi_manager_get_credentials(ssid, sizeof(ssid), password, sizeof(password)) == ESP_OK) {
        ESP_LOGI(TAG, "Starting WiFi with stored credentials");
        ESP_LOGI(TAG, "Attempting to connect to SSID: '%s'", ssid);
        ESP_LOGI(TAG, "SSID length: %d", strlen(ssid));
        
        // Set scan mode to prevent auto-connect
        s_scan_mode = true;
        
        // Start WiFi for scanning
        ESP_ERROR_CHECK(esp_wifi_start());
        
        // Wait a bit for WiFi to initialize
        vTaskDelay(100 / portTICK_PERIOD_MS);
        
        // Scan for available networks
        ESP_LOGI(TAG, "Starting WiFi scan...");
        wifi_scan_config_t scan_config = {
            .ssid = NULL,
            .bssid = NULL,
            .channel = 0,
            .show_hidden = true,
            .scan_type = WIFI_SCAN_TYPE_ACTIVE,
            .scan_time = {
                .active = {
                    .min = 100,
                    .max = 300,
                },
            },
        };
        
        esp_err_t scan_ret = esp_wifi_scan_start(&scan_config, true);
        if (scan_ret != ESP_OK) {
            ESP_LOGE(TAG, "WiFi scan failed with error: %s", esp_err_to_name(scan_ret));
        } else {
            uint16_t ap_count = 0;
            esp_wifi_scan_get_ap_num(&ap_count);
            ESP_LOGI(TAG, "WiFi scan done! Found %d access points", ap_count);
            
            if (ap_count > 0) {
                wifi_ap_record_t *ap_records = malloc(sizeof(wifi_ap_record_t) * ap_count);
                if (ap_records) {
                    esp_wifi_scan_get_ap_records(&ap_count, ap_records);
                    bool target_found = false;
                    for (int i = 0; i < ap_count && i < 20; i++) {
                        ESP_LOGI(TAG, "  %d. SSID: '%s', RSSI: %d, Channel: %d, Auth: %d", 
                                i + 1, 
                                ap_records[i].ssid, 
                                ap_records[i].rssi, 
                                ap_records[i].primary,
                                ap_records[i].authmode);
                        
                        // Check if our target SSID matches
                        if (strcmp((char*)ap_records[i].ssid, ssid) == 0) {
                            ESP_LOGI(TAG, "  *** Target SSID found! Channel: %d, Auth: %d ***", 
                                    ap_records[i].primary, ap_records[i].authmode);
                            target_found = true;
                        }
                    }
                    
                    if (!target_found) {
                        ESP_LOGW(TAG, "Target SSID '%s' not found in scan results!", ssid);
                    }
                    
                    free(ap_records);
                }
            } else {
                ESP_LOGW(TAG, "No access points found. Possible issues:");
                ESP_LOGW(TAG, "  - WiFi antenna not connected");
                ESP_LOGW(TAG, "  - Wrong country code");
                ESP_LOGW(TAG, "  - Hardware issue");
                ESP_LOGW(TAG, "  - All APs on 5GHz only");
            }
        }
        
        // Clear scan mode
        s_scan_mode = false;
        
        // Configure for connection
        wifi_config_t wifi_config = {
            .sta = {
                .threshold.authmode = WIFI_AUTH_OPEN,  // Accept any auth
                .sae_pwe_h2e = WPA3_SAE_PWE_BOTH,
            },
        };
        
        strlcpy((char*)wifi_config.sta.ssid, ssid, sizeof(wifi_config.sta.ssid));
        strlcpy((char*)wifi_config.sta.password, password, sizeof(wifi_config.sta.password));
        
        ESP_LOGI(TAG, "Setting WiFi configuration...");
        ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));
        
        // Now trigger connection
        ESP_LOGI(TAG, "Connecting to WiFi...");
        esp_wifi_connect();
        
        // Wait for connection
        EventBits_t bits = xEventGroupWaitBits(s_wifi_event_group,
                                              WIFI_CONNECTED_BIT | WIFI_FAIL_BIT,
                                              pdFALSE,
                                              pdFALSE,
                                              30000 / portTICK_PERIOD_MS);  // 30 second timeout
        
        if (bits & WIFI_CONNECTED_BIT) {
            ESP_LOGI(TAG, "Connected to AP");
            return ESP_OK;
        } else if (bits & WIFI_FAIL_BIT) {
            ESP_LOGE(TAG, "Failed to connect to AP after retries");
            return ESP_FAIL;
        } else {
            ESP_LOGE(TAG, "WiFi connection timeout");
            return ESP_ERR_TIMEOUT;
        }
    } else {
        ESP_LOGE(TAG, "No WiFi credentials found");
        return ESP_ERR_NOT_FOUND;
    }
}

esp_err_t wifi_manager_stop(void)
{
    esp_err_t ret = esp_wifi_stop();
    if (ret == ESP_OK) {
        s_wifi_state = WIFI_STATE_DISCONNECTED;
        s_retry_num = 0;
        xEventGroupClearBits(s_wifi_event_group, WIFI_CONNECTED_BIT | WIFI_FAIL_BIT);
        ESP_LOGI(TAG, "WiFi stopped");
    }
    return ret;
}

bool wifi_manager_is_connected(void)
{
    return s_wifi_state == WIFI_STATE_CONNECTED;
}

wifi_state_t wifi_manager_get_state(void)
{
    return s_wifi_state;
}

void wifi_manager_register_callback(wifi_event_callback_t callback)
{
    s_event_callback = callback;
}

esp_err_t wifi_manager_set_credentials(const char* ssid, const char* password)
{
    nvs_handle_t nvs_handle;
    esp_err_t ret;
    
    ret = nvs_open(NVS_NAMESPACE, NVS_READWRITE, &nvs_handle);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "Failed to open NVS namespace");
        return ret;
    }
    
    ret = nvs_set_str(nvs_handle, "ssid", ssid);
    if (ret != ESP_OK) {
        nvs_close(nvs_handle);
        return ret;
    }
    
    ret = nvs_set_str(nvs_handle, "password", password);
    if (ret != ESP_OK) {
        nvs_close(nvs_handle);
        return ret;
    }
    
    ret = nvs_commit(nvs_handle);
    nvs_close(nvs_handle);
    
    if (ret == ESP_OK) {
        ESP_LOGI(TAG, "WiFi credentials saved");
    }
    
    return ret;
}

esp_err_t wifi_manager_get_credentials(char* ssid, size_t ssid_len, char* password, size_t pass_len)
{
    nvs_handle_t nvs_handle;
    esp_err_t ret;
    
    ret = nvs_open(NVS_NAMESPACE, NVS_READONLY, &nvs_handle);
    if (ret != ESP_OK) {
        return ret;
    }
    
    ret = nvs_get_str(nvs_handle, "ssid", ssid, &ssid_len);
    if (ret != ESP_OK) {
        nvs_close(nvs_handle);
        return ret;
    }
    
    ret = nvs_get_str(nvs_handle, "password", password, &pass_len);
    nvs_close(nvs_handle);
    
    return ret;
}

esp_err_t wifi_manager_clear_credentials(void)
{
    nvs_handle_t nvs_handle;
    esp_err_t ret;
    
    ret = nvs_open(NVS_NAMESPACE, NVS_READWRITE, &nvs_handle);
    if (ret != ESP_OK) {
        return ret;
    }
    
    nvs_erase_key(nvs_handle, "ssid");
    nvs_erase_key(nvs_handle, "password");
    ret = nvs_commit(nvs_handle);
    nvs_close(nvs_handle);
    
    if (ret == ESP_OK) {
        ESP_LOGI(TAG, "WiFi credentials cleared");
    }
    
    return ret;
}