#include "includes.h"
#include "SEGGER_RTT.h"
#include <stdarg.h>

#if APP_LOG_ENABLE

static char     s_slots[APP_LOG_SLOT_COUNT][APP_LOG_SLOT_SIZE];
static uint16_t s_head;
static uint16_t s_count;
static uint32_t s_overflow;
static uint32_t s_boot_count;
static char     s_ui_page[16] = "boot";
static char     s_debug_level = 'D';
static char     s_cmd_buf[48];
static uint8_t  s_cmd_len;

static uint32_t app_log_ms(void)
{
    return (uint32_t)(rt_tick_get() * 1000U / RT_TICK_PER_SECOND);
}

static void app_log_slot_store(const char *line)
{
    uint16_t idx = s_head;

    strncpy(s_slots[idx], line, APP_LOG_SLOT_SIZE - 1U);
    s_slots[idx][APP_LOG_SLOT_SIZE - 1U] = '\0';
    s_head = (uint16_t)((s_head + 1U) % APP_LOG_SLOT_COUNT);
    if (s_count < APP_LOG_SLOT_COUNT) {
        s_count++;
    } else {
        s_overflow++;
    }
}

void app_log_set_ui_page(const char *name)
{
    if (name == NULL) {
        return;
    }
    strncpy(s_ui_page, name, sizeof(s_ui_page) - 1U);
    s_ui_page[sizeof(s_ui_page) - 1U] = '\0';
}

void app_log_write(char level, const char *cat, const char *fmt, ...)
{
    char line[APP_LOG_SLOT_SIZE];
    va_list ap;
    int n;

    if (level == 'D' && s_debug_level != 'D') {
        return;
    }

    n = snprintf(line, sizeof(line), "[%05u][%c][%-4s] ",
                 (unsigned)app_log_ms(), level, cat);
    if (n < 0) {
        return;
    }
    if ((size_t)n >= sizeof(line)) {
        n = (int)sizeof(line) - 1;
    }

    va_start(ap, fmt);
    vsnprintf(line + n, sizeof(line) - (size_t)n, fmt, ap);
    va_end(ap);

    app_log_slot_store(line);
    SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, line);
    SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, "\n");
}

static void app_log_dump_ram(void)
{
    uint16_t start;
    uint16_t i;

    SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, "LOG_DUMP_BEGIN\n");
    {
        char meta[APP_LOG_SLOT_SIZE];
        snprintf(meta, sizeof(meta),
                 "meta boot=%u lines=%u overflow=%u ui=%s",
                 (unsigned)s_boot_count,
                 (unsigned)s_count,
                 (unsigned)s_overflow,
                 s_ui_page);
        SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, meta);
        SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, "\n");
    }

    if (s_count == 0U) {
        SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, "LOG_DUMP_END\n");
        return;
    }

    start = (s_count < APP_LOG_SLOT_COUNT)
            ? 0U
            : s_head;
    for (i = 0; i < s_count; i++) {
        uint16_t idx = (uint16_t)((start + i) % APP_LOG_SLOT_COUNT);
        SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, s_slots[idx]);
        SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, "\n");
    }
    SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, "LOG_DUMP_END\n");
}

static void app_log_clear_ram(void)
{
    s_head = 0U;
    s_count = 0U;
    s_overflow = 0U;
    memset(s_slots, 0, sizeof(s_slots));
    LOG_I("LOG", "ram cleared");
}

static void app_log_print_status(void)
{
    char line[APP_LOG_SLOT_SIZE];

    snprintf(line, sizeof(line),
             "LOG_STATUS boot=%u lines=%u overflow=%u level=%c ui=%s tick=%u",
             (unsigned)s_boot_count,
             (unsigned)s_count,
             (unsigned)s_overflow,
             s_debug_level,
             s_ui_page,
             (unsigned)app_log_ms());
    SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, line);
    SEGGER_RTT_WriteString(APP_LOG_RTT_CHANNEL, "\n");
}

uint8_t app_log_try_command(const char *cmd)
{
    if (cmd == NULL || cmd[0] == '\0') {
        return 0U;
    }

    if (strncmp(cmd, "log dump", 8) == 0) {
        app_log_dump_ram();
        return 1U;
    }
    if (strncmp(cmd, "log clear", 9) == 0) {
        app_log_clear_ram();
        return 1U;
    }
    if (strncmp(cmd, "log status", 10) == 0) {
        app_log_print_status();
        return 1U;
    }
    if (strncmp(cmd, "log level ", 10) == 0 && cmd[10] != '\0') {
        s_debug_level = cmd[10];
        LOG_I("LOG", "level set %c", s_debug_level);
        return 1U;
    }
    return 0U;
}

static void app_log_feed_char(char c)
{
    if (c == '\r' || c == '\n' || c == '\0') {
        if (s_cmd_len > 0U) {
            s_cmd_buf[s_cmd_len] = '\0';
            (void)app_log_try_command(s_cmd_buf);
        }
        s_cmd_len = 0U;
        s_cmd_buf[0] = '\0';
        return;
    }

    if (s_cmd_len + 1U >= sizeof(s_cmd_buf)) {
        s_cmd_len = 0U;
    }
    s_cmd_buf[s_cmd_len++] = c;
    s_cmd_buf[s_cmd_len] = '\0';
}

void app_log_poll(void)
{
    char rx[16];
    unsigned read_len;
    unsigned i;

    read_len = SEGGER_RTT_Read(APP_LOG_RTT_CHANNEL, rx, sizeof(rx));
    if (read_len == 0U) {
        return;
    }

    for (i = 0; i < read_len; i++) {
        app_log_feed_char(rx[i]);
    }
}

void app_log_init(void)
{
    s_boot_count++;
    LOG_I("BOOT", "app_log init boot=%u", (unsigned)s_boot_count);
}

#else

void app_log_init(void) {}
void app_log_write(char level, const char *cat, const char *fmt, ...) { (void)level; (void)cat; (void)fmt; }
void app_log_poll(void) {}
uint8_t app_log_try_command(const char *cmd) { (void)cmd; return 0U; }
void app_log_set_ui_page(const char *name) { (void)name; }

#endif /* APP_LOG_ENABLE */