#include <stdio.h>

#include "pico/stdlib.h"
#include "pico/multicore.h"
#include "hardware/pio.h"
#include "hardware/uart.h"
#include "hardware/clocks.h"

#include "tusb.h"

#include "iso7816_tx.pio.h"

#define GPIO_SIM_VCC	18		/* pico pin 24 */
#define GPIO_SIM_RST	19		/* pico pin 25 */
#define GPIO_SIM_IO	21		/* pico pin 27 */
#define GPIO_SIM_CLK	20 /* must be at GP20 due to the GPIN0 function; pico pin 26 */

enum cardem_state {
	CST_WAIT_VCC,
	CST_VCC_WAIT_CLK,
	CST_VCC_CLK_WAIT_RST,
	CST_DELAY_BEFORE_ATR,
	CST_IN_ATR,
	CST_WAIT_TPDU_HDR,
	CST_IN_TPDU_HDR,
};

struct cardem_uart_instance {
	enum cardem_state state;
	uint32_t vcc_freq_khz;
	volatile bool vcc_present;
	volatile bool rst_active;

	PIO pio;
	uint sm;
	uint tx_prog_offset;

};

static struct cardem_uart_instance g_cst[1];

const uint8_t g_atr[] = { 0x3B, 0x80, 0x80, 0x81, 0x1F, 0xC7, 0x59 };

static void gpio_callback(uint gpio, uint32_t events)
{
	switch (gpio) {
	case GPIO_SIM_VCC:
		if (events & GPIO_IRQ_EDGE_RISE)
			g_cst[0].vcc_present = true;
#if 1
		if (events & GPIO_IRQ_EDGE_FALL)
			g_cst[0].vcc_present = false;
#endif
		//printf("VCC=%d\n", g_cst[0].vcc_present);
		break;
	case GPIO_SIM_RST:
		if (events & GPIO_IRQ_EDGE_RISE)
			g_cst[0].rst_active = false;
#if 1
		if (events & GPIO_IRQ_EDGE_FALL)
			g_cst[0].rst_active = true;
#endif
		//printf("RST=%d\n", g_cst[0].rst_active);
		break;
	default:
		printf("unhandled GP%u: 0x%x\n", gpio, events);
		break;
	}
}

static void cardem_main_state_chg(struct cardem_uart_instance *cst, enum cardem_state new_st)
{
	//printf("State %u -> %u\n", cst->state, new_st);
	cst->state = new_st;
}

static void cardem_main_loop(struct cardem_uart_instance *cst)
{
	/* global reset on power-off */
	if (cst->state != CST_WAIT_VCC && !cst->vcc_present ) {
		cardem_main_state_chg(cst, CST_WAIT_VCC);
		return;
	}

	switch (cst->state) {
	case CST_WAIT_VCC:
		if (cst->vcc_present)
			cardem_main_state_chg(cst, CST_VCC_WAIT_CLK);
		break;
	case CST_VCC_WAIT_CLK:
		/* determine CLK frequency */
		cst->vcc_freq_khz = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLKSRC_GPIN0);
		if (cst->vcc_freq_khz) {
			//printf("Determined CLK freq: %u kHz\n", cst->vcc_freq_khz);
			cardem_main_state_chg(cst, CST_VCC_CLK_WAIT_RST);
		}
		break;
	case CST_VCC_CLK_WAIT_RST:
#if 1
		if (!cst->rst_active)
			cardem_main_state_chg(cst, CST_DELAY_BEFORE_ATR);
		break;
#endif
	case CST_DELAY_BEFORE_ATR:
		/* FIXME: actually delay */
		if (true) {
			cardem_main_state_chg(cst, CST_IN_ATR);
			/* configure the clock divider for the "correct" baud rate */
			iso7816_tx_program_init(cst->pio, cst->sm, cst->tx_prog_offset, GPIO_SIM_IO,
						(cst->vcc_freq_khz * 1000) / 372);
			/* FIXME: actually start transmission via PIO */
			iso7816_tx_program_puts(cst->pio, cst->sm, g_atr, sizeof(g_atr));
			printf("ATR sent\n");
			cardem_main_state_chg(cst, CST_WAIT_TPDU_HDR);
		}
		break;
	case CST_IN_ATR:
		break;
	case CST_WAIT_TPDU_HDR:
		break;
	case CST_IN_TPDU_HDR:
		break;
	}
}

static void cardem_inst_init(struct cardem_uart_instance *cst)
{
	cst->state = CST_WAIT_VCC;
	cst->vcc_freq_khz = 0;
	cst->vcc_present = false;
	cst->rst_active = false;
	cst->pio = pio0;
	cst->sm = 0;
	cst->tx_prog_offset = pio_add_program(cst->pio, &iso7816_tx_program);
}

static void measure_freqs(void) {
    uint f_pll_sys = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_PLL_SYS_CLKSRC_PRIMARY);
    uint f_pll_usb = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_PLL_USB_CLKSRC_PRIMARY);
    uint f_rosc = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_ROSC_CLKSRC);
    uint f_clk_sys = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_SYS);
    uint f_clk_peri = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_PERI);
    uint f_clk_usb = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_USB);
    uint f_clk_adc = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_ADC);
    uint f_clk_rtc = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_CLK_RTC);

    printf("pll_sys  = %dkHz\n", f_pll_sys);
    printf("pll_usb  = %dkHz\n", f_pll_usb);
    printf("rosc     = %dkHz\n", f_rosc);
    printf("clk_sys  = %dkHz\n", f_clk_sys);
    printf("clk_peri = %dkHz\n", f_clk_peri);
    printf("clk_usb  = %dkHz\n", f_clk_usb);
    printf("clk_adc  = %dkHz\n", f_clk_adc);
    printf("clk_rtc  = %dkHz\n", f_clk_rtc);

    // Can't measure clk_ref / xosc as it is the ref
}

int main()
{
	gpio_debug_pins_init();
#if 1
	//stdio_init_all();
	stdio_usb_init();

	while (!tud_cdc_connected()) {
		printf(".");
		sleep_ms(500);
	}
#else
	/* 115200 bps on GP0/GP1 of RP2040 (at least on pico) */
	setup_default_uart();
#endif
	printf("Starting ISO7816 cardem playground\n");

	measure_freqs();

	cardem_inst_init(&g_cst[0]);

	gpio_set_irq_callback(gpio_callback);
	irq_set_enabled(IO_IRQ_BANK0, true);

	/* GP20 (CLK) as external clock input GPIN0 */
	gpio_set_function(GPIO_SIM_CLK, GPIO_FUNC_GPCK);
	gpio_pull_down(GPIO_SIM_CLK);

	/* GPIO_SIM_VCC as input; edge-triggered interrupts */
	gpio_init(GPIO_SIM_VCC);
	gpio_set_dir(GPIO_SIM_VCC, false);
	gpio_set_slew_rate(GPIO_SIM_VCC, GPIO_SLEW_RATE_SLOW);
	gpio_pull_down(GPIO_SIM_VCC);
	gpio_set_input_enabled(GPIO_SIM_VCC, true);
	gpio_set_irq_enabled(GPIO_SIM_VCC, GPIO_IRQ_EDGE_RISE | GPIO_IRQ_EDGE_FALL, true);

	/* GPIO_SIM_RST as input; edge-triggered interrupts */
	gpio_init(GPIO_SIM_RST);
	gpio_set_dir(GPIO_SIM_RST, false);
	gpio_set_slew_rate(GPIO_SIM_RST, GPIO_SLEW_RATE_SLOW);
	gpio_pull_up(GPIO_SIM_RST);
	gpio_set_input_enabled(GPIO_SIM_RST, true);
	gpio_set_irq_enabled(GPIO_SIM_RST, GPIO_IRQ_EDGE_RISE | GPIO_IRQ_EDGE_FALL, true);

	gpio_pull_up(GPIO_SIM_IO);
	gpio_pull_up(GPIO_SIM_IO);
	gpio_set_function(GPIO_SIM_IO, GPIO_FUNC_PIO0);


	printf("Entering main loop\n");
	while (true) {
		cardem_main_loop(&g_cst[0]);
	}

}