#include "signal_analysis.h"
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "esp_timer.h"
#include <string.h>
#include <stdlib.h>

#define MAX_CHANNELS 165
#define MAX_HISTORY 100

// Channel utilization tracking
static channel_data_t channel_stats[MAX_CHANNELS];
static SemaphoreHandle_t signal_mutex = NULL;

// RSSI history tracking (per BSSID)
typedef struct {
    uint8_t bssid[6];
    int8_t rssi_history[MAX_HISTORY];
    uint32_t timestamps[MAX_HISTORY];
    int head;
    int count;
} rssi_tracker_t;

static rssi_tracker_t rssi_trackers[10];
static int tracker_count = 0;

void signal_update_packet(uint8_t channel, int8_t rssi) {
    if (channel == 0 || channel > MAX_CHANNELS) {
        return;
    }
    
    if (signal_mutex == NULL) {
        signal_mutex = xSemaphoreCreateMutex();
        if (signal_mutex == NULL) {
            return;
        }
    }
    
    if (xSemaphoreTake(signal_mutex, portMAX_DELAY) != pdTRUE) {
        return;
    }
    
    channel_data_t *ch = &channel_stats[channel - 1];
    ch->channel = channel;
    ch->packet_count++;
    ch->rssi = (ch->rssi + rssi) / 2; // Average RSSI
    ch->timestamp = (uint32_t)(esp_timer_get_time() / 1000000ULL);
    
    xSemaphoreGive(signal_mutex);
}

int signal_get_channel_utilization(channel_data_t *data, int max_channels) {
    if (signal_mutex == NULL || data == NULL) {
        return 0;
    }
    
    if (xSemaphoreTake(signal_mutex, portMAX_DELAY) != pdTRUE) {
        return 0;
    }
    
    int count = 0;
    for (int i = 0; i < MAX_CHANNELS && count < max_channels; i++) {
        if (channel_stats[i].packet_count > 0) {
            data[count++] = channel_stats[i];
        }
    }
    
    xSemaphoreGive(signal_mutex);
    return count;
}

int signal_get_rssi_history(uint8_t *bssid, int8_t *rssi_history, uint32_t *timestamps, int max_samples) {
    if (signal_mutex == NULL || bssid == NULL || rssi_history == NULL || timestamps == NULL) {
        return 0;
    }
    
    if (xSemaphoreTake(signal_mutex, portMAX_DELAY) != pdTRUE) {
        return 0;
    }
    
    // Find tracker for this BSSID
    rssi_tracker_t *tracker = NULL;
    for (int i = 0; i < tracker_count; i++) {
        if (memcmp(rssi_trackers[i].bssid, bssid, 6) == 0) {
            tracker = &rssi_trackers[i];
            break;
        }
    }
    
    if (!tracker) {
        xSemaphoreGive(signal_mutex);
        return 0;
    }
    
    int samples = (tracker->count < max_samples) ? tracker->count : max_samples;
    for (int i = 0; i < samples; i++) {
        int idx = (tracker->head - tracker->count + i + MAX_HISTORY) % MAX_HISTORY;
        rssi_history[i] = tracker->rssi_history[idx];
        timestamps[i] = tracker->timestamps[idx];
    }
    
    xSemaphoreGive(signal_mutex);
    return samples;
}