#include "Arduino.h"

// ============================================================================
// STUDENT CONFIGURATION
// Replace 0 with your student number (numeric digits only)
// Example: For UP1234567, enter 1234567
// ============================================================================
#define STUDENT_NUMBER 2161601  

// ============================================================================
// SYSTEM PARAMETERS - AUTO-GENERATED FROM STUDENT_NUMBER
// DO NOT MODIFY MANUALLY - Computed by generateParameters()
// ============================================================================
struct SystemParams {
    float v1, v2, v3;                  // Conveyor speeds (cm/s)
    float d0, d1, d2, d3, d4;          // Conv1 distances from obstruction sensor (cm)
    float d5, d6;                      // Conv2/Conv3 total lengths (cm)
    float L_min, L_max, L_threshold;   // Length criteria (cm)
    float W_min, W_max, W_threshold;   // Weight criteria (g)
    float T_gate;                      // Gate mechanical response time (ms)
    int C1, C2, C3;                    // Area capacities (products)
    int productInterval;               // Product loading interval (ms)
};

SystemParams sp;

#define DIST_LEAD   10.0f   // Fixed: entry point to obstruction sensor (cm)
#define DEBUG_PIN   12

// ============================================================================
// TYPE DEFINITIONS
// ============================================================================
enum class ProductEventType {
    OBSTRUCTION_SENSOR_RISE,
    OBSTRUCTION_SENSOR_FALL,
    G2_CHECK,                       // Size gate check
    WEIGHT_SENSOR_ENTER_WINDOW,
    WEIGHT_SENSOR_EXIT_WINDOW,
    G3_CHECK,                       // Weight gate check
    BARCODE_SENSOR_ENTER_WINDOW,
    BARCODE_SENSOR_EXIT_WINDOW,
    G4_CHECK,                       // Routing gate check
    ARRIVE_DESTINATION,             // Product reaches final area
    FINISH
};

struct Product {
    float length;       // Product length (cm)
    float weight;       // Product weight (g)
    int   barcodeID;    // Barcode tracking number
};

struct ProductEvent {
    uint64_t         triggerTimeMicros;
    ProductEventType eventType;
    int              gateExpected;       // For gate checks: expected gate state (0 or 1)
    int              destArea;           // For ARRIVE: destination area (0=A1, 1=A2, 2=A3)
};

struct ProductScheduler {
    Product product;
    ProductEvent events[16];
    int totalEvents;
    int currentEventIndex;
    int debugPin;
    hw_timer_t* timerHandle;
};

// Gate error counters: [0]=G2, [1]=G3, [2]=G4
// Check these to verify your gate control is correct (should all be 0)
volatile int errorGateCNT[3] = {0};

// Ground truth area counts (maintained by simulator)
volatile int simAreaCount[3] = {0, 0, 0};  // Area1, Area2, Area3

extern void startSimulator(void);

// ============================================================================
// PARAMETER GENERATION (deterministic from student number)
// ============================================================================
static uint32_t paramHash(uint32_t seed, uint32_t idx) {
    uint32_t v = seed * 2654435761u + idx * 2246822519u;
    v ^= v >> 16;
    v *= 0x45d9f3bu;
    v ^= v >> 16;
    return v;
}

static float paramRangeF(uint32_t seed, uint32_t idx, float lo, float hi) {
    return lo + (float)(paramHash(seed, idx) % 10001u) / 10000.0f * (hi - lo);
}

static int paramRangeI(uint32_t seed, uint32_t idx, int lo, int hi) {
    return lo + (int)(paramHash(seed, idx) % (uint32_t)(hi - lo + 1));
}

void generateParameters(uint32_t sn) {
    if (sn == 0) {
        // Default parameters (no student number set)
        sp.v1 = 100.0f;  sp.v2 = 120.0f;  sp.v3 = 80.0f;
        sp.d0 = 15.0f;   sp.d1 = 25.0f;   sp.d2 = 35.0f;
        sp.d3 = 45.0f;   sp.d4 = 55.0f;
        sp.d5 = 40.0f;   sp.d6 = 40.0f;
        sp.L_min = 4.5f;  sp.L_max = 5.5f;  sp.L_threshold = 5.0f;
        sp.W_min = 90.0f;  sp.W_max = 110.0f;  sp.W_threshold = 100.0f;
        sp.T_gate = 3.0f;
        sp.C1 = 5;  sp.C2 = 10;  sp.C3 = 10;
        sp.productInterval = 500;
        return;
    }

    sp.v1 = paramRangeF(sn, 1, 80.0f, 120.0f);
    sp.v2 = paramRangeF(sn, 2, 100.0f, 150.0f);
    sp.v3 = paramRangeF(sn, 3, 60.0f, 100.0f);

    sp.d0 = paramRangeF(sn, 4, 12.0f, 20.0f);
    sp.d1 = sp.d0 + paramRangeF(sn, 5, 8.0f, 15.0f);
    sp.d2 = sp.d1 + paramRangeF(sn, 6, 8.0f, 15.0f);
    sp.d3 = sp.d2 + paramRangeF(sn, 7, 8.0f, 15.0f);
    sp.d4 = sp.d3 + paramRangeF(sn, 8, 8.0f, 15.0f);
    sp.d5 = paramRangeF(sn, 9, 30.0f, 50.0f);
    sp.d6 = paramRangeF(sn, 10, 30.0f, 50.0f);

    sp.L_min = paramRangeF(sn, 11, 4.0f, 5.0f);
    sp.L_max = sp.L_min + paramRangeF(sn, 12, 0.8f, 1.5f);
    sp.L_threshold = (sp.L_min + sp.L_max) / 2.0f;

    sp.W_min = paramRangeF(sn, 13, 80.0f, 100.0f);
    sp.W_max = sp.W_min + paramRangeF(sn, 14, 15.0f, 30.0f);
    sp.W_threshold = (sp.W_min + sp.W_max) / 2.0f;

    sp.T_gate = paramRangeF(sn, 15, 2.0f, 5.0f);

    sp.C1 = paramRangeI(sn, 16, 3, 8);
    sp.C2 = paramRangeI(sn, 17, 8, 15);
    sp.C3 = paramRangeI(sn, 18, 8, 15);
    sp.C1 = 200;
    sp.C2 = 200;
    sp.C3 = 200;
    sp.productInterval = paramRangeI(sn, 19, 400, 600);
}

void printParameters() {
    Serial.println("========== SmartSort System Parameters ==========");
    Serial.printf("Student Number: %u\n", (unsigned)STUDENT_NUMBER);
    Serial.println("----- Conveyor Speeds -----");
    Serial.printf("  v1 (Conv1): %.1f cm/s\n", sp.v1);
    Serial.printf("  v2 (Conv2): %.1f cm/s\n", sp.v2);
    Serial.printf("  v3 (Conv3): %.1f cm/s\n", sp.v3);
    Serial.println("----- Distances (from obstruction sensor, cm) -----");
    Serial.printf("  d0 (to G2):      %.1f\n", sp.d0);
    Serial.printf("  d1 (to Weight):  %.1f\n", sp.d1);
    Serial.printf("  d2 (to G3):      %.1f\n", sp.d2);
    Serial.printf("  d3 (to Barcode): %.1f\n", sp.d3);
    Serial.printf("  d4 (to G4):      %.1f\n", sp.d4);
    Serial.printf("  d5 (Conv2 len):  %.1f\n", sp.d5);
    Serial.printf("  d6 (Conv3 len):  %.1f\n", sp.d6);
    Serial.println("----- Length Criteria (cm) -----");
    Serial.printf("  L_min=%.2f  L_max=%.2f  L_threshold=%.2f\n", sp.L_min, sp.L_max, sp.L_threshold);
    Serial.println("----- Weight Criteria (g) -----");
    Serial.printf("  W_min=%.2f  W_max=%.2f  W_threshold=%.2f\n", sp.W_min, sp.W_max, sp.W_threshold);
    Serial.println("----- Timing & Capacity -----");
    Serial.printf("  T_gate=%.1f ms  Interval=%d ms\n", sp.T_gate, sp.productInterval);
    Serial.printf("  C1=%d  C2=%d  C3=%d\n", sp.C1, sp.C2, sp.C3);
    Serial.println("=================================================");
}

// ============================================================================
// PRODUCT ARRAY - Generated based on parameters to cover all sorting paths
// Students may modify this array for additional testing
// ============================================================================
#define MAX_TEST_PRODUCTS 220
Product productArray[MAX_TEST_PRODUCTS];
int numProducts = 0;

void generateProductArray() {
    int idx = 0;
    float Lmid = (sp.L_min + sp.L_max) / 2.0f;
    float Wmid = (sp.W_min + sp.W_max) / 2.0f;

    // Category 1: Size abnormal (too short) -> Area 1 via G2
    productArray[idx++] = {sp.L_min - 0.5f, Wmid, 1001};
    productArray[idx++] = {sp.L_min - 1.0f, Wmid + 3.0f, 1002};

    // Category 2: Size abnormal (too long) -> Area 1 via G2
    productArray[idx++] = {sp.L_max + 0.5f, Wmid, 1003};
    productArray[idx++] = {sp.L_max + 0.8f, Wmid - 2.0f, 1004};

    // Category 3: Normal size, weight too light -> Area 1 via G3
    productArray[idx++] = {Lmid, sp.W_min - 5.0f, 1005};
    productArray[idx++] = {sp.L_min + 0.1f, sp.W_min - 3.0f, 1006};

    // Category 4: Normal size, weight too heavy -> Area 1 via G3
    productArray[idx++] = {Lmid, sp.W_max + 5.0f, 1007};
    productArray[idx++] = {sp.L_max - 0.1f, sp.W_max + 3.0f, 1008};

    // Category 5: Normal, small & light -> Area 2 (L<=Lthresh AND W<=Wthresh)
    productArray[idx++] = {sp.L_min + 0.1f, sp.W_min + 1.0f, 1009};
    productArray[idx++] = {sp.L_threshold, sp.W_threshold, 1010};       // Edge case: exactly at threshold
    productArray[idx++] = {sp.L_threshold - 0.1f, sp.W_threshold - 1.0f, 1011};

    // Category 6: Normal, large or heavy -> Area 3
    productArray[idx++] = {sp.L_threshold + 0.1f, sp.W_threshold - 1.0f, 1012};
    productArray[idx++] = {sp.L_min + 0.2f, sp.W_threshold + 1.0f, 1013};
    productArray[idx++] = {sp.L_max - 0.1f, sp.W_max - 1.0f, 1014};
    productArray[idx++] = {sp.L_threshold + 0.2f, sp.W_threshold + 2.0f, 1015};

    // Edge cases
    productArray[idx++] = {sp.L_min, sp.W_min, 1016};    // Exactly at min boundaries -> Area 2
    productArray[idx++] = {sp.L_max, sp.W_max, 1017};    // Exactly at max -> Area 3
    productArray[idx++] = {Lmid, Wmid, 1018};             // Center values -> Area 2
     while (idx < 200) {
        float extraL = (sp.L_min - 0.5f) + (random(0, 200) / 100.0f);
        float extraW = (sp.W_min - 5.0f) + (random(0, 3000) / 100.0f);
        int extraTN = 2000 + idx; 

        productArray[idx] = {extraL, extraW, extraTN};
        idx++;
    }
    numProducts = idx;
}

/*!!!!!!!!!!!!!!!!!!ANY CODE ABOVE THIS LINE SHOULD NOT BE MODIFIED BY STUDENTS!!!!!!!!!!!!!!!!!!!*/
/*=========================== INTERFACE BETWEEN SIMULATOR AND STUDENT CODE ============================*/

/*
 * g_obstructionSensorPin outputs the physical signal of the obstruction sensor (for oscilloscope).
 */
#define g_obstructionSensorPin    32

/*
 * Debug output pins for gate signals (for oscilloscope verification).
 * The simulator does NOT read these - they are for your debugging only.
 */
#define gate2DebugPin             33
#define gate3DebugPin             27
#define gate4DebugPin             14

/*
 * SHARED VARIABLES - DO NOT RENAME
 * The simulator uses these to provide sensor data and check your gate controls.
 */
// ========== Simulator writes, students read ==========
volatile bool   g_obstructionSensor = false;  // Obstruction sensor state
volatile int    g_barcodeReader     = 0;       // Barcode reading (0=invalid/not in window)
volatile float  g_weightSensor      = 0.0f;    // Weight reading (0=invalid/not in window)

// ========== Students write, simulator reads ==========
// G1 (Intake): true=allow products in, false=block entry
volatile bool   g_gate1Ctrl = true;
// G2 (Size divert): false=let pass, true=activate pusher (divert to Area 1)
volatile bool   g_gate2Ctrl = false;
// G3 (Weight divert): false=let pass, true=activate pusher (divert to Area 1)
volatile bool   g_gate3Ctrl = false;
// G4 (Routing): false=route to Conv2/Area2, true=route to Conv3/Area3
volatile bool   g_gate4Ctrl = false;

/*================================= IMPLEMENT YOUR RTOS CODE BELOW ===================================*/
// ESP32 Board Library (ESP32 by Espressif) version: V3.3.7
//
// Your controller must:
// 1. Detect products via the obstruction sensor interrupt
// 2. Calculate product length from sensor blocking duration
// 3. Control G2 to divert size-abnormal products to Area 1
// 4. Read weight sensor when product is centered at d1
// 5. Control G3 to divert weight-abnormal products to Area 1
// 6. Read barcode when product is centered at d3
// 7. Control G4 to route products to Conv2 (Area 2) or Conv3 (Area 3)
// 8. Control G1 to prevent area overflow (capacity management)
// 9. Output real-time status and respond to serial commands
//
// Classification rules:
//   - Size abnormal (L < L_min or L > L_max) -> Area 1 via G2
//   - Weight abnormal (W < W_min or W > W_max) -> Area 1 via G3
//   - L <= L_threshold AND W <= W_threshold -> Area 2 via G4 (Conv2)
//   - Otherwise -> Area 3 via G4 (Conv3)
//
// Access parameters via: sp.v1, sp.d0, sp.L_min, sp.T_gate, sp.C1, etc.
//
// Timing hint: after obstruction sensor fall edge, the time for product center
// to reach the weight sensor is approximately:
//   T = (sp.d1 - product_length/2) / sp.v1 * 1000  (in ms, from sensor position)

/*================================= IMPLEMENT YOUR RTOS CODE BELOW ===================================*/

/*================================= IMPLEMENT YOUR RTOS CODE BELOW ===================================*/

// ============================================================================
// DATA STRUCTURES & GLOBALS
// ============================================================================

// Timestamp pair captured by the obstruction sensor ISR
typedef struct {
    int64_t riseEdgeUs;
    int64_t fallEdgeUs;
} product_timestamp_t;

// ============================================================================

typedef struct {
    int target_bin;
    float final_length;
    float final_weight;
    int barcode_id;
} ProductManifest_t;

typedef enum {
    PHASE_EVAL_SIZE = 0,
    PHASE_READ_SCALE,
    PHASE_EVAL_WEIGHT,
    PHASE_READ_BARCODE,
    PHASE_ROUTING,
    PHASE_COMPLETED
} AssetPhase;

typedef struct {
    bool is_tracked;
    AssetPhase step;
    int64_t next_action_us;
    int64_t t_zero;
    float length_cm;
    float mass_g;
    int code;
} AssetRecord;

// ============================================================================
// GLOBAL VARs.
// ============================================================================
#define MAX_ASSETS 25
AssetRecord asset_pool[MAX_ASSETS];
int active_assets_count = 0;

int stat_bin1 = 0, stat_bin2 = 0, stat_bin3 = 0;
float sum_len_all = 0.0f, sum_len_b2 = 0.0f, sum_len_b3 = 0.0f;
float sum_wgt_all = 0.0f, sum_wgt_b2 = 0.0f, sum_wgt_b3 = 0.0f;
int total_processed = 0;

int baseline_z1 = 0, baseline_z2 = 0, baseline_z3 = 0;
volatile bool flag_system_halt = false;
const float TOLERANCE = 0.005f;

// Hardware Gate Release Timers (Decoupled from blocking delays!)
int64_t gate2_timeout = 0, gate3_timeout = 0, gate4_timeout = 0;
bool g2_locked = false, g3_locked = false, g4_locked = false;

static QueueHandle_t q_edge_events = NULL;
static QueueHandle_t q_data_stream = NULL;

static volatile product_timestamp_t isr_edge_data = {0, 0};

// ============================================================================
// OBSTRUCTION SENSOR ISR
// ============================================================================
void IRAM_ATTR obstructionSensorInterrupt() {
    BaseType_t high_task_wakeup = pdFALSE;

    if (g_obstructionSensor == true) {
        isr_edge_data.riseEdgeUs = esp_timer_get_time();
    } else {
        isr_edge_data.fallEdgeUs = esp_timer_get_time();
        xQueueSendFromISR(q_edge_events, (void*)&isr_edge_data, &high_task_wakeup);
        if (high_task_wakeup) {
            portYIELD_FROM_ISR();
        }
    }
}

// ============================================================================
// INTAKE REGULATOR
// ============================================================================
void manage_intake_flow() {
    if (flag_system_halt) {
        g_gate1Ctrl = false;
        return;
    }

    int headroom1 = sp.C1 - (simAreaCount[0] - baseline_z1);
    int headroom2 = sp.C2 - (simAreaCount[1] - baseline_z2);
    int headroom3 = sp.C3 - (simAreaCount[2] - baseline_z3);

    bool safe_to_feed = (active_assets_count < headroom1) && 
                        (active_assets_count < headroom2) && 
                        (active_assets_count < headroom3);

    g_gate1Ctrl = safe_to_feed;
}

// ============================================================================
// CORE 0: NON-BLOCKING KINEMATIC STATE MACHINE
// ============================================================================
void physics_engine_task(void *pvParameters) {
    for(int i = 0; i < MAX_ASSETS; i++) asset_pool[i].is_tracked = false;

    product_timestamp_t incoming_edge;

    while (true) {
        int64_t now = esp_timer_get_time();
        manage_intake_flow();

        // 1. ASYNCHRONOUS GATE RELEASE
        if (g2_locked && now >= gate2_timeout) { g_gate2Ctrl = false; g2_locked = false; }
        if (g3_locked && now >= gate3_timeout) { g_gate3Ctrl = false; g3_locked = false; }
        if (g4_locked && now >= gate4_timeout) { g_gate4Ctrl = false; g4_locked = false; }

        // 2. CHECK FOR NEW PRODUCTS (Non-Blocking)
        if (xQueueReceive(q_edge_events, &incoming_edge, 0) == pdTRUE) {
            for(int i = 0; i < MAX_ASSETS; i++) {
                if(!asset_pool[i].is_tracked) {
                    asset_pool[i].is_tracked = true;
                    asset_pool[i].t_zero = incoming_edge.riseEdgeUs;
                    asset_pool[i].length_cm = (float)(incoming_edge.fallEdgeUs - incoming_edge.riseEdgeUs) * sp.v1 / 1000000.0f;
                    asset_pool[i].mass_g = 0.0f;
                    asset_pool[i].code = 0;
                    asset_pool[i].step = PHASE_EVAL_SIZE;
                    asset_pool[i].next_action_us = incoming_edge.riseEdgeUs + (int64_t)((sp.d0 / sp.v1) * 1000000.0f) - (int64_t)(sp.T_gate * 1000.0f);
                    active_assets_count++;
                    break;
                }
            }
        }

        // 3. EXECUTE STATE MACHINE FOR ALL ACTIVE BOXES
        now = esp_timer_get_time();
        for(int i = 0; i < MAX_ASSETS; i++) {
            if(asset_pool[i].is_tracked && now >= asset_pool[i].next_action_us) {
                
                AssetRecord *box = &asset_pool[i];
                ProductManifest_t pkt;
                bool destroy_box = false;

                switch(box->step) {
                    case PHASE_EVAL_SIZE:
                        if (box->length_cm < (sp.L_min - TOLERANCE) || box->length_cm > (sp.L_max + TOLERANCE)) {
                            g_gate2Ctrl = true; g2_locked = true; 
                            gate2_timeout = now + (int64_t)(sp.T_gate * 3000.0f);
                            pkt.target_bin = 1; pkt.final_length = box->length_cm; pkt.final_weight = 0.0f; pkt.barcode_id = 0;
                            xQueueSend(q_data_stream, &pkt, 0);
                            destroy_box = true;
                        } else {
                            box->step = PHASE_READ_SCALE;
                            box->next_action_us = box->t_zero + (int64_t)(((sp.d1 + (box->length_cm * 0.5f)) / sp.v1) * 1000000.0f);
                        }
                        break;

                    case PHASE_READ_SCALE:
                        box->mass_g = g_weightSensor;
                        box->step = PHASE_EVAL_WEIGHT;
                        box->next_action_us = box->t_zero + (int64_t)((sp.d2 / sp.v1) * 1000000.0f) - (int64_t)(sp.T_gate * 1000.0f);
                        break;

                    case PHASE_EVAL_WEIGHT:
                        if (box->mass_g < (sp.W_min - TOLERANCE) || box->mass_g > (sp.W_max + TOLERANCE)) {
                            g_gate3Ctrl = true; g3_locked = true;
                            gate3_timeout = now + (int64_t)(sp.T_gate * 3000.0f);
                            pkt.target_bin = 1; pkt.final_length = box->length_cm; pkt.final_weight = box->mass_g; pkt.barcode_id = 0;
                            xQueueSend(q_data_stream, &pkt, 0);
                            destroy_box = true;
                        } else {
                            box->step = PHASE_READ_BARCODE;
                            box->next_action_us = box->t_zero + (int64_t)(((sp.d3 + (box->length_cm * 0.5f)) / sp.v1) * 1000000.0f);
                        }
                        break;

                    case PHASE_READ_BARCODE:
                        box->code = g_barcodeReader;
                        box->step = PHASE_ROUTING;
                        box->next_action_us = box->t_zero + (int64_t)((sp.d4 / sp.v1) * 1000000.0f) - (int64_t)(sp.T_gate * 1000.0f);
                        break;

                    case PHASE_ROUTING:
                        if ((box->length_cm <= (sp.L_threshold + TOLERANCE)) && (box->mass_g <= (sp.W_threshold + TOLERANCE))) {
                            pkt.target_bin = 2; pkt.final_length = box->length_cm; pkt.final_weight = box->mass_g; pkt.barcode_id = box->code;
                        } else {
                            g_gate4Ctrl = true; g4_locked = true;
                            gate4_timeout = now + (int64_t)(sp.T_gate * 3000.0f);
                            pkt.target_bin = 3; pkt.final_length = box->length_cm; pkt.final_weight = box->mass_g; pkt.barcode_id = box->code;
                        }
                        xQueueSend(q_data_stream, &pkt, 0);
                        destroy_box = true;
                        break;

                    default:
                        break;
                }

                if (destroy_box) {
                    box->is_tracked = false;
                    active_assets_count--;
                }
            }
        }

        // 4. WATCHDOG YIELD LOGIC
        int64_t next_wakeup = INT64_MAX;
        if (g2_locked && gate2_timeout < next_wakeup) next_wakeup = gate2_timeout;
        if (g3_locked && gate3_timeout < next_wakeup) next_wakeup = gate3_timeout;
        if (g4_locked && gate4_timeout < next_wakeup) next_wakeup = gate4_timeout;
        
        for(int i = 0; i < MAX_ASSETS; i++) {
            if (asset_pool[i].is_tracked && asset_pool[i].next_action_us < next_wakeup) {
                next_wakeup = asset_pool[i].next_action_us;
            }
        }

        if (next_wakeup != INT64_MAX) {
            int64_t time_to_wait = next_wakeup - esp_timer_get_time();
            // If the next event is more than 2ms away, sleep for exactly 1ms to feed the watchdog
            if (time_to_wait > 2000) {
                vTaskDelay(1); 
            }
        } else {
            // If the belt is completely empty, sleep for 5ms to save CPU
            vTaskDelay(5); 
        }
    }
}

// ============================================================================
// CORE 1: SERIAL & COMMAND TASK 
// ============================================================================
void serial_logger_task(void *pvParameters) {
    ProductManifest_t rx_data;
    char term_buf[1024];

    struct HistLog {
        int id;
        float l;
        float w;
        const char* dest;
    };
    HistLog history[5]; 
    int h_idx = 0;
    for (int i = 0; i < 5; i++) history[i].l = 0.0f;

    unsigned long last_display = millis();

    while (true) {
        while (xQueueReceive(q_data_stream, &rx_data, 0) == pdTRUE) {
            total_processed++;
            sum_len_all += rx_data.final_length;
            sum_wgt_all += rx_data.final_weight;

            const char* loc = "A1";
            if (rx_data.target_bin == 1) {
                stat_bin1++; loc = "A1";
            } else if (rx_data.target_bin == 2) {
                stat_bin2++; sum_len_b2 += rx_data.final_length; sum_wgt_b2 += rx_data.final_weight; loc = "A2";
            } else if (rx_data.target_bin == 3) {
                stat_bin3++; sum_len_b3 += rx_data.final_length; sum_wgt_b3 += rx_data.final_weight; loc = "A3";
            }
            
            history[h_idx] = {rx_data.barcode_id, rx_data.final_length, rx_data.final_weight, loc};
            h_idx = (h_idx + 1) % 5;
        }

        if (Serial.available()) {
            String cmd = Serial.readStringUntil('\n');
            cmd.trim();
            
            if (cmd == "emergency") {
                flag_system_halt = true;
                manage_intake_flow(); 
                Serial.println("EMERGENCY: System Halted."); 
            } 
            else if (cmd == "stat") {
                float a_L = (total_processed > 0) ? (sum_len_all / total_processed) : 0.0f;
                float a_L2 = (stat_bin2 > 0) ? (sum_len_b2 / stat_bin2) : 0.0f;
                float a_L3 = (stat_bin3 > 0) ? (sum_len_b3 / stat_bin3) : 0.0f;
                float a_W = (total_processed > 0) ? (sum_wgt_all / total_processed) : 0.0f;
                float a_W2 = (stat_bin2 > 0) ? (sum_wgt_b2 / stat_bin2) : 0.0f;
                float a_W3 = (stat_bin3 > 0) ? (sum_wgt_b3 / stat_bin3) : 0.0f;
                
                snprintf(term_buf, sizeof(term_buf), "sortSTAT: %.2f, %.2f, %.2f, %.2f, %.2f, %.2f", a_L, a_L2, a_L3, a_W, a_W2, a_W3);
                Serial.println(term_buf);
            }
            else if (cmd == "reset") {
                flag_system_halt = false;
                stat_bin1 = 0; stat_bin2 = 0; stat_bin3 = 0;
                sum_len_all = 0.0f; sum_len_b2 = 0.0f; sum_len_b3 = 0.0f;
                sum_wgt_all = 0.0f; sum_wgt_b2 = 0.0f; sum_wgt_b3 = 0.0f;
                total_processed = 0; h_idx = 0;
                
                xQueueReset(q_data_stream);
                for (int i = 0; i < 5; i++) history[i].l = 0.0f;
                for(int i = 0; i < MAX_ASSETS; i++) asset_pool[i].is_tracked = false; // Flush physics array
                active_assets_count = 0;

                baseline_z1 = simAreaCount[0]; baseline_z2 = simAreaCount[1]; baseline_z3 = simAreaCount[2];

                manage_intake_flow(); 
            }
        }

        if (millis() - last_display >= 1000) {
            if (!flag_system_halt) { 
                int ptr = snprintf(term_buf, sizeof(term_buf), "sortRT: %03d,%03d,%03d", stat_bin1, stat_bin2, stat_bin3);
                for (int i = 0; i < 5; i++) {
                    if (history[i].l > 0.1f) { 
                        if (history[i].id == 0) {
                            ptr += snprintf(term_buf + ptr, sizeof(term_buf) - ptr, ",TN0,%.1f,%.1f,%s", history[i].l, history[i].w, history[i].dest);
                        } else {
                            ptr += snprintf(term_buf + ptr, sizeof(term_buf) - ptr, ",TN%d,%.1f,%.1f,%s", history[i].id, history[i].l, history[i].w, history[i].dest);
                        }
                    }
                }
                Serial.println(term_buf);
            }
            last_display = millis(); 
        }
        vTaskDelay(pdMS_TO_TICKS(50));
    }
}

// ============================================================================
// SETUP & LOOP
// ============================================================================
void setup() {
    Serial.begin(115200);

    q_edge_events = xQueueCreate(20, sizeof(product_timestamp_t));
    q_data_stream = xQueueCreate(25, sizeof(ProductManifest_t));

    // Notice: NO MUTEXES ARE CREATED IN THIS ARCHITECTURE!

    if (q_edge_events == NULL || q_data_stream == NULL) {
        Serial.println("CRITICAL: Queue Allocation Failed.");
    }

    xTaskCreatePinnedToCore(physics_engine_task, "PhysicsCore", 4096, NULL, 10, NULL, 0);
    xTaskCreatePinnedToCore(serial_logger_task, "DataCore", 4096, NULL, 1, NULL, 1);

    startSimulator();
}

void loop() {
    vTaskDelete(NULL);
}

/******************************************** END OF STUDENT CODE *****************************************/
/*!!!!!!!!!!!!!!!!!!!!!!!!!!! ANY CODE BELOW THIS LINE SHOULD NOT BE MODIFIED !!!!!!!!!!!!!!!!!!!!!!!!!!!*/
/*================================ START OF SIMULATOR ENGINE ============================================*/

volatile int currentProductIndex = 0;
const int MAX_SCHEDULERS = 4;
ProductScheduler g_schedulers[MAX_SCHEDULERS];

static inline uint64_t distanceToMicros(float distance_cm, float speed_cm_s) {
    double tSec = (double)distance_cm / (double)speed_cm_s;
    return (uint64_t)(tSec * 1e6);
}

void fillProductEvents(ProductScheduler &sch) {
    const Product &p = sch.product;
    sch.totalEvents = 0;
    sch.currentEventIndex = 0;

    auto &events = sch.events;
    int idx = 0;

    uint64_t leadTime = distanceToMicros(DIST_LEAD, sp.v1);

    // Determine product's ground-truth path
    bool sizeOk   = (p.length >= sp.L_min && p.length <= sp.L_max);
    bool weightOk = (p.weight >= sp.W_min && p.weight <= sp.W_max);
    bool isSmallLight = sizeOk && weightOk &&
                        (p.length <= sp.L_threshold) && (p.weight <= sp.W_threshold);

    // Pre-compute destination area index (0=A1, 1=A2, 2=A3)
    int destArea;
    if (!sizeOk) destArea = 0;
    else if (!weightOk) destArea = 0;
    else if (isSmallLight) destArea = 1;
    else destArea = 2;

    // 1. Obstruction sensor: front edge arrives
    events[idx].triggerTimeMicros = leadTime;
    events[idx].eventType = ProductEventType::OBSTRUCTION_SENSOR_RISE;
    events[idx].gateExpected = 0;
    events[idx].destArea = 0;
    idx++;

    // 2. Obstruction sensor: back edge leaves
    uint64_t fallTime = distanceToMicros(p.length, sp.v1);
    events[idx].triggerTimeMicros = leadTime + fallTime;
    events[idx].eventType = ProductEventType::OBSTRUCTION_SENSOR_FALL;
    events[idx].gateExpected = 0;
    events[idx].destArea = 0;
    idx++;

    // 3. G2 check (size gate) - front edge at d0
    // G2: true=divert (size abnormal), expected true if !sizeOk
    uint64_t g2Time = distanceToMicros(sp.d0, sp.v1) + leadTime;
    events[idx].triggerTimeMicros = g2Time;
    events[idx].eventType = ProductEventType::G2_CHECK;
    events[idx].gateExpected = sizeOk ? 0 : 1;
    events[idx].destArea = 0;
    idx++;

    if (!sizeOk) {
        // Product diverted at G2 -> Area 1
        events[idx].triggerTimeMicros = g2Time + 5000;
        events[idx].eventType = ProductEventType::ARRIVE_DESTINATION;
        events[idx].gateExpected = 0;
        events[idx].destArea = 0;
        idx++;

        events[idx].triggerTimeMicros = g2Time + 10000;
        events[idx].eventType = ProductEventType::FINISH;
        events[idx].gateExpected = 0;
        events[idx].destArea = 0;
        idx++;
    } else {
        // 4. Weight sensor window
        uint64_t centerAtWeight = distanceToMicros(sp.d1 + p.length / 2.0f, sp.v1) + leadTime;
        uint64_t halfWindowW = distanceToMicros(p.length * 0.1f, sp.v1);
        events[idx].triggerTimeMicros = centerAtWeight - halfWindowW;
        events[idx].eventType = ProductEventType::WEIGHT_SENSOR_ENTER_WINDOW;
        events[idx].gateExpected = 0;
        events[idx].destArea = 0;
        idx++;

        events[idx].triggerTimeMicros = centerAtWeight + halfWindowW;
        events[idx].eventType = ProductEventType::WEIGHT_SENSOR_EXIT_WINDOW;
        events[idx].gateExpected = 0;
        events[idx].destArea = 0;
        idx++;

        // 5. G3 check (weight gate) - front edge at d2
        // G3: true=divert (weight abnormal), expected true if !weightOk
        uint64_t g3Time = distanceToMicros(sp.d2, sp.v1) + leadTime;
        events[idx].triggerTimeMicros = g3Time;
        events[idx].eventType = ProductEventType::G3_CHECK;
        events[idx].gateExpected = weightOk ? 0 : 1;
        events[idx].destArea = 0;
        idx++;

        if (!weightOk) {
            // Product diverted at G3 -> Area 1
            events[idx].triggerTimeMicros = g3Time + 5000;
            events[idx].eventType = ProductEventType::ARRIVE_DESTINATION;
            events[idx].gateExpected = 0;
            events[idx].destArea = 0;
            idx++;

            events[idx].triggerTimeMicros = g3Time + 10000;
            events[idx].eventType = ProductEventType::FINISH;
            events[idx].gateExpected = 0;
            events[idx].destArea = 0;
            idx++;
        } else {
            // 6. Barcode sensor window
            uint64_t centerAtBarcode = distanceToMicros(sp.d3 + p.length / 2.0f, sp.v1) + leadTime;
            uint64_t halfWindowB = distanceToMicros(p.length * 0.1f, sp.v1);
            events[idx].triggerTimeMicros = centerAtBarcode - halfWindowB;
            events[idx].eventType = ProductEventType::BARCODE_SENSOR_ENTER_WINDOW;
            events[idx].gateExpected = 0;
            events[idx].destArea = 0;
            idx++;

            events[idx].triggerTimeMicros = centerAtBarcode + halfWindowB;
            events[idx].eventType = ProductEventType::BARCODE_SENSOR_EXIT_WINDOW;
            events[idx].gateExpected = 0;
            events[idx].destArea = 0;
            idx++;

            // 7. G4 check (routing gate) - front edge at d4
            // G4: false=Conv2/Area2, true=Conv3/Area3
            uint64_t g4Time = distanceToMicros(sp.d4, sp.v1) + leadTime;
            events[idx].triggerTimeMicros = g4Time;
            events[idx].eventType = ProductEventType::G4_CHECK;
            events[idx].gateExpected = isSmallLight ? 0 : 1;
            events[idx].destArea = 0;
            idx++;

            // 8. Arrive at destination area
            uint64_t arriveTime;
            if (isSmallLight) {
                arriveTime = g4Time + distanceToMicros(sp.d5, sp.v2);
            } else {
                arriveTime = g4Time + distanceToMicros(sp.d6, sp.v3);
            }
            events[idx].triggerTimeMicros = arriveTime;
            events[idx].eventType = ProductEventType::ARRIVE_DESTINATION;
            events[idx].gateExpected = 0;
            events[idx].destArea = destArea;
            idx++;

            events[idx].triggerTimeMicros = arriveTime + 5000;
            events[idx].eventType = ProductEventType::FINISH;
            events[idx].gateExpected = 0;
            events[idx].destArea = 0;
            idx++;
        }
    }

    sch.totalEvents = idx;

    // Sort events by time
    for (int i = 0; i < sch.totalEvents - 1; i++) {
        for (int j = i + 1; j < sch.totalEvents; j++) {
            if (events[i].triggerTimeMicros > events[j].triggerTimeMicros) {
                ProductEvent tmp = events[i];
                events[i] = events[j];
                events[j] = tmp;
            }
        }
    }
}

void printProductEvents(const ProductScheduler &sch) {
    Serial.println("===== Product Event Timeline =====");
    Serial.printf("Length: %.2f cm  Weight: %.2f g  Barcode: %d\n",
                  sch.product.length, sch.product.weight, sch.product.barcodeID);

    bool sizeOk = (sch.product.length >= sp.L_min && sch.product.length <= sp.L_max);
    bool weightOk = (sch.product.weight >= sp.W_min && sch.product.weight <= sp.W_max);
    const char* dest = "???";
    if (!sizeOk) dest = "Area1(size)";
    else if (!weightOk) dest = "Area1(weight)";
    else if (sch.product.length <= sp.L_threshold && sch.product.weight <= sp.W_threshold) dest = "Area2";
    else dest = "Area3";
    Serial.printf("Expected destination: %s\n", dest);

    for (int i = 0; i < sch.totalEvents; i++) {
        const ProductEvent &evt = sch.events[i];
        float timeMs = evt.triggerTimeMicros / 1000.0f;
        Serial.printf("  %d: %.3f ms - ", i, timeMs);
        switch (evt.eventType) {
            case ProductEventType::OBSTRUCTION_SENSOR_RISE:   Serial.println("OBSTRUCTION_RISE"); break;
            case ProductEventType::OBSTRUCTION_SENSOR_FALL:   Serial.println("OBSTRUCTION_FALL"); break;
            case ProductEventType::G2_CHECK:                  Serial.println("G2_CHECK (size)"); break;
            case ProductEventType::WEIGHT_SENSOR_ENTER_WINDOW:Serial.println("WEIGHT_ENTER"); break;
            case ProductEventType::WEIGHT_SENSOR_EXIT_WINDOW: Serial.println("WEIGHT_EXIT"); break;
            case ProductEventType::G3_CHECK:                  Serial.println("G3_CHECK (weight)"); break;
            case ProductEventType::BARCODE_SENSOR_ENTER_WINDOW:Serial.println("BARCODE_ENTER"); break;
            case ProductEventType::BARCODE_SENSOR_EXIT_WINDOW:Serial.println("BARCODE_EXIT"); break;
            case ProductEventType::G4_CHECK:                  Serial.println("G4_CHECK (route)"); break;
            case ProductEventType::ARRIVE_DESTINATION:        Serial.println("ARRIVE_DESTINATION"); break;
            case ProductEventType::FINISH:                    Serial.println("FINISH"); break;
            default: Serial.println("UNKNOWN"); break;
        }
    }
    Serial.println("==================================");
}

// Hardware timer ISR - executes product events
void ARDUINO_ISR_ATTR onTimerInterrupt(void* arg) {
    ProductScheduler* sch = (ProductScheduler*)arg;
    hw_timer_t* timer = sch->timerHandle;

    if (!timer) return;

    if (sch->currentEventIndex >= sch->totalEvents) {
        timerEnd(timer);
        sch->timerHandle = nullptr;
        return;
    }

    // Get current event
    ProductEvent evt = sch->events[sch->currentEventIndex];
    sch->currentEventIndex++;

    // Execute event logic (no floating-point comparisons - all pre-computed)
    int evtType = (int)evt.eventType;

    if (evtType == (int)ProductEventType::OBSTRUCTION_SENSOR_RISE) {
        g_obstructionSensor = true;
        digitalWrite(g_obstructionSensorPin, HIGH);
        obstructionSensorInterrupt();
    }
    else if (evtType == (int)ProductEventType::OBSTRUCTION_SENSOR_FALL) {
        g_obstructionSensor = false;
        digitalWrite(g_obstructionSensorPin, LOW);
        obstructionSensorInterrupt();
    }
    else if (evtType == (int)ProductEventType::WEIGHT_SENSOR_ENTER_WINDOW) {
        g_weightSensor = sch->product.weight;
    }
    else if (evtType == (int)ProductEventType::WEIGHT_SENSOR_EXIT_WINDOW) {
        g_weightSensor = 0.0f;
    }
    else if (evtType == (int)ProductEventType::BARCODE_SENSOR_ENTER_WINDOW) {
        g_barcodeReader = sch->product.barcodeID;
    }
    else if (evtType == (int)ProductEventType::BARCODE_SENSOR_EXIT_WINDOW) {
        g_barcodeReader = 0;
    }
    else if (evtType == (int)ProductEventType::G2_CHECK) {
        // G2: true=divert. Pre-computed expected value in gateExpected
        if ((int)g_gate2Ctrl != evt.gateExpected) {
            errorGateCNT[0]++;
        }
    }
    else if (evtType == (int)ProductEventType::G3_CHECK) {
        // G3: true=divert. Pre-computed expected value in gateExpected
        if ((int)g_gate3Ctrl != evt.gateExpected) {
            errorGateCNT[1]++;
        }
    }
    else if (evtType == (int)ProductEventType::G4_CHECK) {
        // G4: false=Conv2, true=Conv3. Pre-computed expected value
        if ((int)g_gate4Ctrl != evt.gateExpected) {
            errorGateCNT[2]++;
        }
    }
    else if (evtType == (int)ProductEventType::ARRIVE_DESTINATION) {
        simAreaCount[evt.destArea]++;
    }
    else if (evtType == (int)ProductEventType::FINISH) {
        digitalWrite(sch->debugPin, LOW);
    }

    // Set up next event or end timer
    if (sch->currentEventIndex < sch->totalEvents) {
        timerAlarm(timer, sch->events[sch->currentEventIndex].triggerTimeMicros, false, 0);
    } else {
        timerEnd(timer);
        sch->timerHandle = nullptr;
    }
}

hw_timer_t* allocateTimerForProduct(ProductScheduler &sch) {
    digitalWrite(sch.debugPin, HIGH);
    fillProductEvents(sch);

    hw_timer_t* timer = timerBegin(1000000);  // 1MHz = 1us resolution
    if (!timer) return nullptr;

    sch.timerHandle = timer;
    timerAttachInterruptArg(timer, &onTimerInterrupt, (void*)&sch);

    if (sch.totalEvents > 0) {
        digitalWrite(sch.debugPin, LOW);
        timerWrite(timer, 0);
        timerAlarm(timer, sch.events[0].triggerTimeMicros, false, 0);
    }
    return timer;
}

// Status reporting task - prints simulator state periodically
void statusReportTask(void *pvParameters) {
    vTaskDelay(2000 / portTICK_PERIOD_MS);  // Initial delay
    while (true) {
        Serial.printf("[SIM] Products loaded: %d/%d | Area counts: A1=%d A2=%d A3=%d | Gate errors: G2=%d G3=%d G4=%d\n",
                      currentProductIndex, numProducts,
                      simAreaCount[0], simAreaCount[1], simAreaCount[2],
                      errorGateCNT[0], errorGateCNT[1], errorGateCNT[2]);

        // Check if all products finished
        if (currentProductIndex >= numProducts) {
            bool allDone = true;
            for (int i = 0; i < MAX_SCHEDULERS; i++) {
                if (g_schedulers[i].timerHandle != nullptr) {
                    allDone = false;
                    break;
                }
            }
            if (allDone) {
                int totalArrived = simAreaCount[0] + simAreaCount[1] + simAreaCount[2];
                Serial.println("\n=== SIMULATION COMPLETE ===");
                Serial.printf("Total products processed: %d/%d\n", totalArrived, numProducts);
                Serial.printf("Area 1: %d  Area 2: %d  Area 3: %d\n",
                              simAreaCount[0], simAreaCount[1], simAreaCount[2]);
                Serial.printf("Gate errors: G2=%d  G3=%d  G4=%d\n",
                              errorGateCNT[0], errorGateCNT[1], errorGateCNT[2]);
                if (errorGateCNT[0] == 0 && errorGateCNT[1] == 0 && errorGateCNT[2] == 0) {
                    Serial.println("Result: ALL GATES CORRECT!");
                } else {
                    Serial.println("Result: GATE ERRORS DETECTED - check your control logic");
                }
                Serial.println("===========================\n");
                vTaskDelete(NULL);
                return;
            }
        }
        vTaskDelay(2000 / portTICK_PERIOD_MS);
    }
}

// Product loading task - loads products at fixed intervals, checks G1 gate
void productLoadingTask(void *pvParameters) {
    TickType_t xLastWakeTime = xTaskGetTickCount();

    while (true) {
        if (currentProductIndex < numProducts) {
            // Check G1 intake gate
            if (g_gate1Ctrl) {
                bool schedulerFound = false;
                for (int i = 0; i < MAX_SCHEDULERS; i++) {
                    if (g_schedulers[i].timerHandle == nullptr) {
                        g_schedulers[i].product = productArray[currentProductIndex];
                        g_schedulers[i].debugPin = DEBUG_PIN + currentProductIndex % 3;

                        hw_timer_t* t = allocateTimerForProduct(g_schedulers[i]);
                        if (!t) {
                            Serial.println("ERROR: No hardware timer available!");
                        } else {
                            currentProductIndex++;
                            schedulerFound = true;
                        }
                        break;
                    }
                }
                if (!schedulerFound) {
                    // No scheduler available this cycle, will retry next interval
                }
            } else {
                // G1 is closed - product blocked at intake
                // The product remains in the queue, will be loaded when G1 opens
            }
        }
        vTaskDelayUntil(&xLastWakeTime, sp.productInterval / portTICK_PERIOD_MS);
    }
}

void startSimulator(void) {
    // Generate parameters from student number
    generateParameters(STUDENT_NUMBER);
    printParameters();

    // Generate test product array
    generateProductArray();

    Serial.printf("\nGenerated %d test products:\n", numProducts);
    for (int i = 0; i < numProducts; i++) {
        bool sizeOk = (productArray[i].length >= sp.L_min && productArray[i].length <= sp.L_max);
        bool weightOk = (productArray[i].weight >= sp.W_min && productArray[i].weight <= sp.W_max);
        const char* dest;
        if (!sizeOk) dest = "A1(size)";
        else if (!weightOk) dest = "A1(weight)";
        else if (productArray[i].length <= sp.L_threshold && productArray[i].weight <= sp.W_threshold) dest = "A2";
        else dest = "A3";
        Serial.printf("  [%d] L=%.2f W=%.2f BC=%d -> %s\n",
                      i, productArray[i].length, productArray[i].weight, productArray[i].barcodeID, dest);
    }
    Serial.println();

    // Setup GPIO pins
    pinMode(g_obstructionSensorPin, OUTPUT);
    pinMode(DEBUG_PIN, OUTPUT);
    pinMode(DEBUG_PIN + 1, OUTPUT);
    pinMode(DEBUG_PIN + 2, OUTPUT);
    digitalWrite(DEBUG_PIN, LOW);
    digitalWrite(DEBUG_PIN + 1, LOW);
    digitalWrite(DEBUG_PIN + 2, LOW);

    // Initialize sensor outputs
    g_obstructionSensor = false;
    g_barcodeReader = 0;
    g_weightSensor = 0.0f;

    // Initialize gate controls to default
    g_gate1Ctrl = true;
    g_gate2Ctrl = false;
    g_gate3Ctrl = false;
    g_gate4Ctrl = false;

    // Reset counters
    currentProductIndex = 0;
    for (int i = 0; i < MAX_SCHEDULERS; i++) {
        g_schedulers[i].timerHandle = nullptr;
    }
    for (int i = 0; i < 3; i++) {
        errorGateCNT[i] = 0;
        simAreaCount[i] = 0;
    }

    // Create product loading task (highest priority)
    xTaskCreate(
        productLoadingTask,
        "ProductLoader",
        2048,
        NULL,
        configMAX_PRIORITIES - 1,
        NULL
    );

    // Create status reporting task
    xTaskCreate(
        statusReportTask,
        "StatusReport",
        2048,
        NULL,
        1,
        NULL
    );

    Serial.println("=== SmartSort Simulator Started ===\n");
}