#include "ds18b20.h"
#include "ds18b20_config.h"
#include <string.h>

#define OW_SEARCH_ROM 0xF0U
#define OW_MATCH_ROM 0x55U
#define OW_SKIP_ROM 0xCCU
#define DS_CONVERT 0x44U
#define DS_READ_SCRATCHPAD 0xBEU
#define DS_WRITE_SCRATCHPAD 0x4EU
#define DS_COPY_SCRATCHPAD 0x48U
#define DS_RECALL_E2 0xB8U

static int valid_instance(const ds18b20_t *d)
{
    return d && d->ops && d->ops->drive_low && d->ops->release &&
           d->ops->read && d->ops->delay_us && d->roms && d->rom_capacity;
}

static void critical(ds18b20_t *d, int enter)
{
    if (enter && d->ops->critical_enter) d->ops->critical_enter(d->platform_context);
    if (!enter && d->ops->critical_exit) d->ops->critical_exit(d->platform_context);
}

static void write_bit(ds18b20_t *d, uint8_t bit)
{
    critical(d, 1);
    d->ops->drive_low(d->platform_context);
    d->ops->delay_us(d->platform_context, bit ? 6U : 60U);
    d->ops->release(d->platform_context);
    d->ops->delay_us(d->platform_context, bit ? 64U : 10U);
    critical(d, 0);
    if (d->search_active)
        d->ops->delay_us(d->platform_context, DS18B20_SLOT_RECOVERY_EXTRA_US);
}

static uint8_t read_bit(ds18b20_t *d)
{
    uint8_t bit;
    critical(d, 1);
    d->ops->drive_low(d->platform_context);
    d->ops->delay_us(d->platform_context, 3U);
    d->ops->release(d->platform_context);
    d->ops->delay_us(d->platform_context, 10U);
    bit = d->ops->read(d->platform_context) ? 1U : 0U;
    d->ops->delay_us(d->platform_context, 57U);
    critical(d, 0);
    if (d->search_active)
        d->ops->delay_us(d->platform_context, DS18B20_SLOT_RECOVERY_EXTRA_US);
    return bit;
}

static void write_byte(ds18b20_t *d, uint8_t value)
{
    uint8_t i;
    for (i = 0; i < 8U; ++i) { write_bit(d, value & 1U); value >>= 1U; }
}

static uint8_t read_byte(ds18b20_t *d)
{
    uint8_t i, value = 0U;
    for (i = 0; i < 8U; ++i) value |= (uint8_t)(read_bit(d) << i);
    return value;
}

static ds18b20_status_t reset(ds18b20_t *d)
{
    uint8_t level;
    d->ops->drive_low(d->platform_context);
    d->ops->delay_us(d->platform_context, 480U);
    /* Protect release-to-presence sampling from interrupt latency. */
    critical(d, 1);
    d->ops->release(d->platform_context);
    d->ops->delay_us(d->platform_context, 70U);
    level = d->ops->read(d->platform_context);
    critical(d, 0);
    d->ops->delay_us(d->platform_context, 410U);
    return level ? DS18B20_E_NO_DEVICE : DS18B20_OK;
}

static void match(ds18b20_t *d, const uint8_t *rom)
{
    uint8_t i; write_byte(d, OW_MATCH_ROM);
    for (i = 0U; i < 8U; ++i) write_byte(d, rom[i]);
}

uint8_t ds18b20_crc8(const void *data, size_t length)
{
    const uint8_t *p = (const uint8_t *)data; uint8_t crc = 0U;
    while (length--) { uint8_t in = *p++, i; for (i = 0U; i < 8U; ++i) {
        uint8_t mix = (uint8_t)((crc ^ in) & 1U); crc >>= 1U;
        if (mix) crc ^= 0x8CU; in >>= 1U; } }
    return crc;
}

ds18b20_status_t ds18b20_validate_rom(const uint8_t rom[8])
{
    if (!rom) return DS18B20_E_ARGUMENT;
    if (rom[0] != DS18B20_FAMILY_CODE) return DS18B20_E_ROM;
    return ds18b20_crc8(rom, 7U) == rom[7] ? DS18B20_OK : DS18B20_E_CRC;
}

ds18b20_status_t ds18b20_init(ds18b20_t *d, const ds18b20_onewire_ops_t *ops,
 void *ctx, uint8_t (*roms)[8], size_t capacity)
{
    if (!d || !ops || !roms || !capacity || !ops->drive_low || !ops->release ||
        !ops->read || !ops->delay_us) return DS18B20_E_ARGUMENT;
    memset(d, 0, sizeof(*d)); d->ops = ops; d->platform_context = ctx;
    d->roms = roms; d->rom_capacity = capacity; ops->release(ctx);
    return DS18B20_OK;
}

static ds18b20_status_t search_next(ds18b20_t *d)
{
    uint8_t bit_no=1U,last_zero=0U,byte_no=0U,mask=1U;
    ds18b20_status_t reset_status;
    if (d->last_device) return DS18B20_OK;
    d->search_diagnostics.last_error_bit = 0U;
    d->search_diagnostics.last_error_pair = 0xFFU;
    reset_status=reset(d);
    if (reset_status != DS18B20_OK) return reset_status;
    write_byte(d, OW_SEARCH_ROM);
    while (byte_no < 8U) {
        uint8_t id=read_bit(d), cmp=read_bit(d), dir;
        d->search_diagnostics.last_error_bit = bit_no;
        d->search_diagnostics.last_error_pair = (uint8_t)((id << 1U) | cmp);
        if (id && cmp) break;
        if (id != cmp) dir=id; else { dir=(bit_no<d->last_discrepancy) ?
          ((d->search_rom[byte_no]&mask)!=0U) : (bit_no==d->last_discrepancy);
          if (!dir) { last_zero=bit_no; if (last_zero<9U) d->last_family_discrepancy=last_zero; } }
        if (dir) d->search_rom[byte_no]|=mask; else d->search_rom[byte_no]&=(uint8_t)~mask;
        write_bit(d,dir); ++bit_no; mask<<=1U; if (!mask) { ++byte_no; mask=1U; }
    }
    if (bit_no < 65U || !d->search_rom[0]) {
        d->last_discrepancy=0; d->last_device=0; return DS18B20_E_IO;
    }
    d->last_discrepancy=last_zero;
    if (!last_zero) d->last_device=1U;
    return DS18B20_E_BUSY;
}

/* Reset only traversal state: the union of validated ROMs survives passes. */
static void search_tree_reset(ds18b20_t *d)
{
    d->last_discrepancy = 0U;
    d->last_family_discrepancy = 0U;
    d->last_device = 0U;
    d->search_retries = 0U;
    memset(d->search_rom, 0, sizeof(d->search_rom));
}

static ds18b20_status_t search_stop(ds18b20_t *d, ds18b20_status_t result)
{
    d->search_active = 0U;
    d->search_result = result;
    return result;
}

static ds18b20_status_t search_pass_finish(ds18b20_t *d, uint8_t complete)
{
    ds18b20_search_diagnostics_t *diag = &d->search_diagnostics;
    ++diag->passes_finished;
    if (complete) ++diag->complete_passes;
    if (diag->passes_finished < DS18B20_SEARCH_PASSES) {
        search_tree_reset(d);
        return DS18B20_E_BUSY;
    }
    /* A completed traversal can recover earlier faults. Without one, retain
     * the partial catalog but report the failure instead of claiming success. */
    if (diag->complete_passes != 0U)
        return search_stop(d, d->rom_count ? DS18B20_OK : DS18B20_E_NO_DEVICE);
    return search_stop(d, diag->last_error);
}

ds18b20_status_t ds18b20_search_begin(ds18b20_t *d)
{
    if (!valid_instance(d)) return DS18B20_E_ARGUMENT;
    if (d->strong_pullup_active) return DS18B20_E_BUSY;
    d->rom_count = 0U;
    search_tree_reset(d);
    memset(&d->search_diagnostics, 0, sizeof(d->search_diagnostics));
    d->search_diagnostics.last_error_pair = 0xFFU;
    d->search_active = 1U;
    d->search_result = DS18B20_E_BUSY;
    return DS18B20_E_BUSY;
}

ds18b20_status_t ds18b20_search_step(ds18b20_t *d)
{
    uint8_t previous_rom[8], previous_discrepancy, previous_family;
    ds18b20_search_diagnostics_t previous_diag;
    ds18b20_status_t status;
    if (!valid_instance(d)) return DS18B20_E_ARGUMENT;
    if (!d->search_active) return d->search_result;
    if (d->search_diagnostics.attempts >= DS18B20_SEARCH_MAX_ATTEMPTS) {
        d->search_diagnostics.last_error = DS18B20_E_TIMEOUT;
        d->search_diagnostics.last_error_bit = 0U;
        d->search_diagnostics.last_error_pair = 0xFFU;
        return search_stop(d, DS18B20_E_TIMEOUT);
    }
    /* Snapshot the preceding validated tree path BEFORE touching the wire.
     * A corrupt ROM must never become the path for the following attempt. */
    memcpy(previous_rom, d->search_rom, 8U);
    previous_discrepancy = d->last_discrepancy;
    previous_family = d->last_family_discrepancy;
    previous_diag = d->search_diagnostics;
    ++d->search_diagnostics.attempts;
    status = search_next(d);
    if (status == DS18B20_E_BUSY) {
        /* CRC first: a valid non-DS18B20 family is skipped without corrupting
         * the traversal; a bad family caused by noise still gets retried. */
        status = ds18b20_crc8(d->search_rom, 7U) == d->search_rom[7] ?
                 DS18B20_OK : DS18B20_E_CRC;
        if (status == DS18B20_OK && d->search_rom[0] == DS18B20_FAMILY_CODE)
            status = ds18b20_add_known_rom(d, d->search_rom);
    }
    if (status == DS18B20_OK) {
        /* Keep the last FAILURE location, even when a later retry succeeds. */
        d->search_diagnostics.last_error_bit = previous_diag.last_error_bit;
        d->search_diagnostics.last_error_pair = previous_diag.last_error_pair;
        d->search_retries = 0U;
        return d->last_device ? search_pass_finish(d, 1U) : DS18B20_E_BUSY;
    }
    d->search_diagnostics.last_error = status;
    if (status == DS18B20_E_CAPACITY) return search_stop(d, status);
    if (status == DS18B20_E_CRC) ++d->search_diagnostics.crc_errors;
    else ++d->search_diagnostics.io_errors;
    memcpy(d->search_rom, previous_rom, 8U);
    d->last_discrepancy = previous_discrepancy;
    d->last_family_discrepancy = previous_family;
    d->last_device = 0U;
    if (d->search_retries < DS18B20_SEARCH_RETRIES) {
        ++d->search_retries;
        ++d->search_diagnostics.retries;
        return DS18B20_E_BUSY;
    }
    return search_pass_finish(d, 0U);
}

ds18b20_status_t ds18b20_search(ds18b20_t *d)
{
    ds18b20_status_t status;
    if (!valid_instance(d)) return DS18B20_E_ARGUMENT;
    if (d->strong_pullup_active) return DS18B20_E_BUSY;
    status = ds18b20_search_begin(d);
    while (status == DS18B20_E_BUSY) status = ds18b20_search_step(d);
    return status;
}

ds18b20_status_t ds18b20_add_known_rom(ds18b20_t *d, const uint8_t rom[8])
{
    size_t i;
    ds18b20_status_t status;
    if (!valid_instance(d)) return DS18B20_E_ARGUMENT;
    status = ds18b20_validate_rom(rom);
    if (status != DS18B20_OK) return status;
    for (i = 0U; i < d->rom_count; ++i)
        if (memcmp(d->roms[i], rom, 8U) == 0) return DS18B20_OK;
    if (d->rom_count >= d->rom_capacity) return DS18B20_E_CAPACITY;
    memcpy(d->roms[d->rom_count++], rom, 8U);
    return DS18B20_OK;
}

size_t ds18b20_count(const ds18b20_t *d) { return valid_instance(d) ? d->rom_count : 0U; }
const uint8_t *ds18b20_rom(const ds18b20_t *d,size_t i) { return valid_instance(d)&&i<d->rom_count?d->roms[i]:NULL; }

ds18b20_status_t ds18b20_start_all(ds18b20_t *d)
{ if(!valid_instance(d))return DS18B20_E_ARGUMENT; if(reset(d))return DS18B20_E_NO_DEVICE; write_byte(d,OW_SKIP_ROM);write_byte(d,DS_CONVERT);return DS18B20_OK; }
ds18b20_status_t ds18b20_start(ds18b20_t *d,const uint8_t *rom)
{ ds18b20_status_t s;if(!valid_instance(d)||!rom)return DS18B20_E_ARGUMENT;if(ds18b20_validate_rom(rom))return DS18B20_E_ROM;s=reset(d);if(s)return s;match(d,rom);write_byte(d,DS_CONVERT);return DS18B20_OK; }
ds18b20_status_t ds18b20_conversion_ready(ds18b20_t *d)
{ if(!valid_instance(d))return DS18B20_E_ARGUMENT;return read_bit(d)?DS18B20_OK:DS18B20_E_BUSY; }
ds18b20_status_t ds18b20_wait(ds18b20_t *d,uint32_t timeout)
{ uint32_t start;if(!valid_instance(d)||!d->ops->tick_ms)return DS18B20_E_ARGUMENT;start=d->ops->tick_ms(d->platform_context);while(!read_bit(d))if((uint32_t)(d->ops->tick_ms(d->platform_context)-start)>timeout)return DS18B20_E_TIMEOUT;return DS18B20_OK; }
ds18b20_status_t ds18b20_read_scratchpad(ds18b20_t *d,const uint8_t *rom,uint8_t *sp)
{ uint8_t i;ds18b20_status_t s;if(!valid_instance(d)||!rom||!sp)return DS18B20_E_ARGUMENT;if(ds18b20_validate_rom(rom))return DS18B20_E_ROM;s=reset(d);if(s)return s;match(d,rom);write_byte(d,DS_READ_SCRATCHPAD);for(i=0;i<9U;++i)sp[i]=read_byte(d);return ds18b20_crc8(sp,8U)==sp[8]?DS18B20_OK:DS18B20_E_CRC; }
ds18b20_status_t ds18b20_decode_temperature(const uint8_t *sp,float *out)
{ int16_t raw;uint8_t cfg;if(!sp||!out)return DS18B20_E_ARGUMENT;if(ds18b20_crc8(sp,8U)!=sp[8])return DS18B20_E_CRC;cfg=sp[4]&0x60U;raw=(int16_t)((uint16_t)sp[0]|((uint16_t)sp[1]<<8));if(cfg==0)raw&=(int16_t)~7;else if(cfg==0x20)raw&=(int16_t)~3;else if(cfg==0x40)raw&=(int16_t)~1;else if(cfg!=0x60)return DS18B20_E_IO;*out=(float)raw/16.0f;return DS18B20_OK; }

static ds18b20_status_t write_config(ds18b20_t *d,const uint8_t *rom,uint8_t th,uint8_t tl,uint8_t cfg)
{
    uint8_t chunk;
    ds18b20_status_t s=ds18b20_write_scratchpad(d,rom,th,tl,cfg);
    if(s)return s;s=ds18b20_copy_scratchpad_start(d,rom,0U);if(s)return s;
    /* TIM1 counter is 16-bit: at 72 ticks/us a single 10 ms wait can never
     * satisfy the port comparison. Short chunks preserve wrap-safe timing. */
    for(chunk=0U;chunk<100U;++chunk)d->ops->delay_us(d->platform_context,100U);
    return ds18b20_copy_scratchpad_finish(d,0U);
}
ds18b20_status_t ds18b20_set_resolution(ds18b20_t *d,const uint8_t *rom,uint8_t bits)
{ uint8_t sp[9],cfg;ds18b20_status_t s;if(bits<9U||bits>12U)return DS18B20_E_ARGUMENT;s=ds18b20_read_scratchpad(d,rom,sp);if(s)return s;cfg=(uint8_t)(0x1FU|((bits-9U)<<5));return write_config(d,rom,sp[2],sp[3],cfg); }
ds18b20_status_t ds18b20_write_user_bytes(ds18b20_t *d,const uint8_t *rom,int16_t b12,int16_t b34,uint8_t mask)
{ uint8_t sp[9];ds18b20_status_t s=ds18b20_read_scratchpad(d,rom,sp);(void)b34;if(s)return s;if(mask&1U)sp[2]=(uint8_t)b12;if(mask&2U)sp[3]=(uint8_t)(b12>>8);/* DS18B20 физически позволяет записать только TH/TL/config; байты 6/7 read-only. */return write_config(d,rom,sp[2],sp[3],sp[4]); }

ds18b20_status_t ds18b20_write_scratchpad(ds18b20_t *d,const uint8_t *rom,
 uint8_t th,uint8_t tl,uint8_t cfg)
{
    ds18b20_status_t s;
    if(!valid_instance(d)||!rom)return DS18B20_E_ARGUMENT;
    s=ds18b20_validate_rom(rom);if(s)return s;
    s=reset(d);if(s)return s;match(d,rom);write_byte(d,DS_WRITE_SCRATCHPAD);
    write_byte(d,th);write_byte(d,tl);write_byte(d,cfg);return DS18B20_OK;
}

ds18b20_status_t ds18b20_copy_scratchpad_start(ds18b20_t *d,const uint8_t *rom,
 uint8_t parasite)
{
    ds18b20_status_t s;
    if(!valid_instance(d)||!rom)return DS18B20_E_ARGUMENT;
    if(parasite && !d->ops->strong_pullup)return DS18B20_E_POWER;
    s=ds18b20_validate_rom(rom);if(s)return s;
    s=reset(d);if(s)return s;match(d,rom);write_byte(d,DS_COPY_SCRATCHPAD);
    /* The pull-up must be asserted immediately after the command slot. */
    if(parasite){d->ops->strong_pullup(d->platform_context,1U);
        d->strong_pullup_active=1U;}
    return DS18B20_OK;
}

ds18b20_status_t ds18b20_copy_scratchpad_finish(ds18b20_t *d,uint8_t parasite)
{
    if(!valid_instance(d))return DS18B20_E_ARGUMENT;
    if(parasite){if(!d->ops->strong_pullup)return DS18B20_E_POWER;
        if(d->strong_pullup_active){d->ops->strong_pullup(d->platform_context,0U);
            d->strong_pullup_active=0U;}}
    d->ops->release(d->platform_context);return DS18B20_OK;
}

ds18b20_status_t ds18b20_recall_e2(ds18b20_t *d,const uint8_t *rom)
{
    ds18b20_status_t s;if(!valid_instance(d)||!rom)return DS18B20_E_ARGUMENT;
    s=ds18b20_validate_rom(rom);if(s)return s;s=reset(d);if(s)return s;
    match(d,rom);write_byte(d,DS_RECALL_E2);return DS18B20_OK;
}

ds18b20_status_t ds18b20_recall_ready(ds18b20_t *d)
{if(!valid_instance(d))return DS18B20_E_ARGUMENT;return read_bit(d)?DS18B20_OK:DS18B20_E_BUSY;}

void ds18b20_recover_bus(ds18b20_t *d)
{
    if(!valid_instance(d))return;
    if(d->strong_pullup_active&&d->ops->strong_pullup){
        d->ops->strong_pullup(d->platform_context,0U);d->strong_pullup_active=0U;}
    d->ops->release(d->platform_context);
}

uint8_t ds18b20_search_retry_due(const ds18b20_t *d,uint8_t conversion_active,
 uint32_t now,uint32_t last,uint32_t period)
{
    if(!valid_instance(d)||d->rom_count!=0U||conversion_active||period==0U)return 0U;
    /* Unsigned subtraction keeps the retry correct across HAL tick rollover. */
    return ((uint32_t)(now-last)>=period)?1U:0U;
}