/* 五路输出电压的换算与设定。与硬件无关，宿主机与 ESP32-S3 上编的是同一份。 */
#include "rail.h"

#include <assert.h>
#include <stddef.h>

#include "dac63204.h"
#include "phonerail.h"

/* 五路数与 DAC 侧的映射表必须是同一个数 —— 分家的那天就是错一路的那天。 */
_Static_assert(PHONERAIL_RAIL_COUNT == DAC63204_RAIL_COUNT, "五路数对不上");

bool rail_mv_in_range(int mv)
{
    return mv >= RAIL_MV_MIN && mv <= RAIL_MV_MAX;
}

uint16_t rail_mv_to_code(int mv)
{
    assert(rail_mv_in_range(mv)); /* 越界要在 rail_set_mv() 里被拒掉，不该走到这儿 */

    /* code = (Vout0 − Vout) / 486416 µV × 4096，四舍五入。
       **减法在这里**：Vout 越低，差越大，码越大 —— 反向关系只此一处。 */
    int64_t diff_uv = (int64_t)RAIL_VOUT0_UV - (int64_t)mv * 1000;
    int64_t code = (diff_uv * DAC63204_CODE_SPAN + RAIL_DAC_SPAN_UV / 2) / RAIL_DAC_SPAN_UV;

    if (code < 0) {
        code = 0;
    }
    if (code > DAC63204_CODE_MAX) {
        code = DAC63204_CODE_MAX;
    }
    return (uint16_t)code;
}

int rail_code_to_mv(uint16_t code)
{
    int64_t drop_uv = ((int64_t)code * RAIL_DAC_SPAN_UV + DAC63204_CODE_SPAN / 2)
                      / DAC63204_CODE_SPAN;
    int64_t uv = (int64_t)RAIL_VOUT0_UV - drop_uv;
    return (int)((uv + 500) / 1000);
}

int32_t rail_code_to_vd_uv(uint16_t code)
{
    return dac63204_code_to_uv(code);
}

hal_err_t rail_volt_init(void)
{
    const uint16_t safe = rail_mv_to_code(RAIL_MV_SAFE);

    for (int i = 0; i < DAC63204_COUNT; i++) {
        uint8_t addr = dac63204_all_addr[i];
        hal_err_t err = dac63204_probe(addr);
        if (err != HAL_OK) {
            return err;
        }
        /* init 自己就把用到的通道写成 safe 了（上电之前写，见 dac63204_init 的 ③）。 */
        err = dac63204_init(addr, safe);
        if (err != HAL_OK) {
            return err;
        }
    }
    return HAL_OK;
}

hal_err_t rail_set_mv(int rail, int mv)
{
    if (rail < 1 || rail > PHONERAIL_RAIL_COUNT) {
        return HAL_ERR_ARG;
    }
    if (!rail_mv_in_range(mv)) {
        return HAL_ERR_ARG; /* SR-13。TODO(A11)：这里要记一条事件 */
    }
    return dac63204_write_code(dac63204_rail_addr(rail), dac63204_rail_ch(rail),
                               rail_mv_to_code(mv));
}

hal_err_t rail_get_mv(int rail, int *mv)
{
    if (rail < 1 || rail > PHONERAIL_RAIL_COUNT || mv == NULL) {
        return HAL_ERR_ARG;
    }
    uint16_t code = 0;
    hal_err_t err = dac63204_read_code(dac63204_rail_addr(rail), dac63204_rail_ch(rail), &code);
    if (err != HAL_OK) {
        return err;
    }
    *mv = rail_code_to_mv(code);
    return HAL_OK;
}