/* Lab 5 - Software State Machines 
   Combination Lock System 
   Personal Combination: 110, 3, 71 */

#include "stm32f1xx.h"
#include <stdint.h>

// Personal Combination Numbers
#define Num1 110 
#define Num2 3   
#define Num3 71  

// Pin Bitmasks
#define LED1_PIN     (1U << 5)  // PB5
#define LED2_PIN     (1U << 6)  // PB6
#define LED3_PIN     (1U << 7)  // PB7
#define PASS_PIN     (1U << 8)  // PB8
#define FAIL_PIN     (1U << 9)  // PB9
#define LOCKIN_PIN   (1U << 0)  // PB0
#define RESTART_PIN  (1U << 1)  // PB1

#define ALL_LEDS (LED1_PIN | LED2_PIN | LED3_PIN | PASS_PIN | FAIL_PIN)

// Function Prototypes
void gpio_init(void);
void usart_init(void);
void set_leds(uint32_t mask);
uint8_t read_switches(void);
void uart_print(const char* str);
void print_status(const char* state_name, uint8_t sw, uint8_t expected);

// State Definitions
typedef enum { Check1, Check2, Check3, Pass, Fail } State_t;

int main(void) {
    gpio_init();
    usart_init();

    State_t state = Check1;
    uint8_t sw;

    while (1) {
        // Global Restart Check
        if (!(GPIOB->IDR & RESTART_PIN)) {
            state = Check1;
            while (!(GPIOB->IDR & RESTART_PIN)); // Wait for release
        }

        switch (state) {
            case Check1:
                set_leds(0); 
                if (!(GPIOB->IDR & LOCKIN_PIN)) {
                    sw = read_switches();
                    print_status("Check1", sw, Num1);
                    if (sw == Num1) state = Check2;
                    else state = Fail;
                    while (!(GPIOB->IDR & LOCKIN_PIN)); 
                }
                break;

            case Check2:
                set_leds(LED1_PIN);
                if (!(GPIOB->IDR & LOCKIN_PIN)) {
                    sw = read_switches();
                    print_status("Check2", sw, Num2);
                    if (sw == Num2) state = Check3;
                    else state = Fail;
                    while (!(GPIOB->IDR & LOCKIN_PIN));
                }
                break;

            case Check3:
                set_leds(LED1_PIN | LED2_PIN);
                if (!(GPIOB->IDR & LOCKIN_PIN)) {
                    sw = read_switches();
                    print_status("Check3", sw, Num3);
                    if (sw == Num3) state = Pass;
                    else state = Fail;
                    while (!(GPIOB->IDR & LOCKIN_PIN));
                }
                break;

            case Pass:
                set_leds(LED1_PIN | LED2_PIN | LED3_PIN | PASS_PIN);
                break;

            case Fail:
                set_leds(FAIL_PIN);
                break;
        }
    }
}

void set_leds(uint32_t mask) {
    GPIOB->ODR &= ~ALL_LEDS;
    GPIOB->ODR |= (mask & ALL_LEDS);
    GPIOB->ODR |= (LOCKIN_PIN | RESTART_PIN);
}

uint8_t read_switches(void) {
    // FIXED: Added ~ to invert logic because your hardware reads 255 when OFF
    return (uint8_t)(~(GPIOA->IDR) & 0xFF);
}

void gpio_init(void) {
    RCC->APB2ENR |= (RCC_APB2ENR_IOPAEN | RCC_APB2ENR_IOPBEN);
    GPIOA->CRL = 0x44444444; // Input Floating
    GPIOB->CRL = 0x22288888; // PB0, PB1 Input Pull-up; PB5, PB6, PB7 Output
    GPIOB->CRH = (GPIOB->CRH & 0xFFFFFF00) | 0x22; // PB8, PB9 Output
    GPIOB->ODR |= (LOCKIN_PIN | RESTART_PIN);
}

void usart_init(void) {
    RCC->APB2ENR |= RCC_APB2ENR_USART1EN | RCC_APB2ENR_IOPAEN;
    GPIOA->CRH = (GPIOA->CRH & ~GPIO_CRH_CNF9) | GPIO_CRH_CNF9_1;
    GPIOA->CRH = (GPIOA->CRH & ~GPIO_CRH_MODE9) | GPIO_CRH_MODE9_0 | GPIO_CRH_MODE9_1;
    USART1->BRR = 0x341; 
    USART1->CR1 = USART_CR1_UE | USART_CR1_TE;
}

void uart_write(int ch) {
    while (!(USART1->SR & USART_SR_TXE));
    USART1->DR = (ch & 0xFF);
}

void uart_print(const char* str) {
    while (*str) uart_write(*str++);
}

void print_status(const char* state_name, uint8_t sw, uint8_t expected) {
    uart_print("\r\n[");
    uart_print(state_name);
    uart_print("] Sw: ");
    
    char buf[4];
    int i = 0;
    uint8_t temp = sw;
    if (temp == 0) buf[i++] = '0';
    else {
        if (temp >= 100) { buf[i++] = (temp / 100) + '0'; temp %= 100; }
        if (temp >= 10 || i > 0) { buf[i++] = (temp / 10) + '0'; temp %= 10; }
        buf[i++] = temp + '0';
    }
    buf[i] = '\0';
    uart_print(buf);

    uart_print(" | Expected: ");
    
    i = 0;
    temp = expected;
    if (temp == 0) buf[i++] = '0';
    else {
        if (temp >= 100) { buf[i++] = (temp / 100) + '0'; temp %= 100; }
        if (temp >= 10 || i > 0) { buf[i++] = (temp / 10) + '0'; temp %= 10; }
        buf[i++] = temp + '0';
    }
    buf[i] = '\0';
    uart_print(buf);
    uart_print("\r\n");
}