#include <string.h>

#include "wm_include.h"

#include "drivers/nl_led.h"

#define SM_ADDR_CURRENT 0xC0u
#define SM_ADDR_WY      0xC5u
#define SM_CHANNEL_WY   0x80u /* channel select bit 7: 0 = RGB, 1 = WY */
#define SM_CHANNEL_STBY 0x20u /* standby bit 5: powers the outputs down */

extern void delay_us(unsigned int us); /* provided by libwlan.a */

static uint8_t s_clk, s_dat, s_current;
static uint8_t s_last[NL_CH_COUNT];
static bool s_have_last;

static void pin(uint8_t p, int v)
{
    tls_gpio_write((enum tls_io_name)p, (u8)v);
}

static void bus_start(void)
{
    pin(s_clk, 1); pin(s_dat, 1); delay_us(1);
    pin(s_dat, 0); delay_us(1);
    pin(s_clk, 0); delay_us(1);
}

static void bus_stop(void)
{
    pin(s_clk, 0); pin(s_dat, 0); delay_us(1);
    pin(s_clk, 1); delay_us(1);
    pin(s_dat, 1); delay_us(1);
}

static void write_byte(uint8_t b)
{
    for (uint8_t m = 0x80; m; m >>= 1) {
        pin(s_dat, (b & m) ? 1 : 0); delay_us(1);
        pin(s_clk, 1); delay_us(1);
        pin(s_clk, 0); delay_us(1);
    }
    /* ack clock; the SM2135EH does not drive an ack */
    pin(s_dat, 0); delay_us(1);
    pin(s_clk, 1); delay_us(1);
    pin(s_clk, 0); pin(s_dat, 0);
}

static void sm_send(const uint8_t *d, int n)
{
    bus_start();
    for (int i = 0; i < n; i++)
        write_byte(d[i]);
    bus_stop();
}

void nl_sm2135eh_init(const nl_board_t *board)
{
    uint8_t off[NL_CH_COUNT] = {0};
    s_clk = board->sm_clk_pin;
    s_dat = board->sm_dat_pin;
    s_current = board->sm_current;
    s_have_last = false;
    tls_gpio_cfg((enum tls_io_name)s_clk, WM_GPIO_DIR_OUTPUT, WM_GPIO_ATTR_PULLHIGH);
    tls_gpio_cfg((enum tls_io_name)s_dat, WM_GPIO_DIR_OUTPUT, WM_GPIO_ATTR_PULLHIGH);
    nl_sm2135eh_set(off);
}

void nl_sm2135eh_set(const uint8_t ch[NL_CH_COUNT])
{
    bool white = ch[NL_CH_CW] || ch[NL_CH_WW];

    if (s_have_last && memcmp(ch, s_last, NL_CH_COUNT) == 0)
        return;
    memcpy(s_last, ch, NL_CH_COUNT);
    s_have_last = true;

    if (!white) {
        /* All channels dark: put the driver into standby instead of just writing zero duty.
           Without bit 5 the chip stays active and leaks enough current to keep the lamp
           faintly glowing - measured on a migrated GU10 RGB, 2026-09-13. The old QConnex
           firmware had this logic but left it commented out (qcl_lamp.c), which is why the
           behaviour was inherited. Lamps driven straight from PWM pins (G95, the CW variants)
           are unaffected. Turning back on writes 0x00 or SM_CHANNEL_WY here and clears it. */
        bool dark = !ch[NL_CH_R] && !ch[NL_CH_G] && !ch[NL_CH_B];
        uint8_t chan = dark ? SM_CHANNEL_STBY : 0x00u;
        uint8_t d[6] = {SM_ADDR_CURRENT, s_current, chan, ch[NL_CH_B], ch[NL_CH_G], ch[NL_CH_R]};
        sm_send(d, 6);
        /* The WY data registers are cleared here too, even though this is the RGB branch:
           the chip keeps whatever white value was last written, and a direct white -> colour
           change never passes through the all-dark frame above. The stale white then bleeds
           through as soon as the colour dims - the same defect as the colour -> white case
           below (fixed in 00d5a4c, 2026-09-13), just mirrored: that fix made the WY branch
           also write the (always-zero) RGB registers, this makes the RGB branch also write
           the (always-zero) WY registers. Both directions had it; only one was caught first. */
        uint8_t w[3] = {SM_ADDR_WY, 0, 0};
        sm_send(w, 3);
    } else {
        /* The RGB data registers are written along with the channel select, even though they
           are always zero here: the chip keeps whatever colour was last written, and a direct
           colour -> white change never passes through the all-dark frame above. The stale
           colour then bleeds through as soon as the white dims - visible as a coloured
           fade-out on a migrated GU10 RGB, 2026-09-13. */
        uint8_t h[6] = {SM_ADDR_CURRENT, s_current, SM_CHANNEL_WY,
                        ch[NL_CH_B], ch[NL_CH_G], ch[NL_CH_R]};
        uint8_t d[3] = {SM_ADDR_WY, ch[NL_CH_WW], ch[NL_CH_CW]};
        sm_send(h, 6);
        sm_send(d, 3);
    }
}