/**
 * @file app_cli.c
 * @brief CLI UART frontend: an independent task receives command lines from
 *        the USART1 RX interrupt queue, handles line editing (backspace,
 *        history, TAB completion, Ctrl+Z) and hands finished lines to the
 *        transport-agnostic CLI core (cli_core.c). Command table and command
 *        handlers live in cli_core.c.
 *
 * Line terminators: "\r\n", "\n\r", "\r" and "\n" are all accepted.
 * Editing: backspace (0x08 / 0x7F) erases the last character.
 */
#include "app_cli.h"
#include "cli_core.h"
#include "bsp_usart.h"
#include "app_tasks.h"

#include <string.h>

#include "FreeRTOS.h"
#include "task.h"

#define CLI_TASK_STACK      1024  /* in words (printf needs more stack) */
#define CLI_TASK_PRIO       3
#define CLI_LINE_BUF_SIZE   64
#define CLI_HISTORY_SIZE    8     /* number of remembered command lines */
#define CLI_PROMPT          "caiic->"

/* Key codes */
#define CLI_KEY_TAB         0x09
#define CLI_KEY_ESC         0x1B
#define CLI_KEY_CTRL_Z      0x1A
#define CLI_KEY_BACKSPACE   0x08
#define CLI_KEY_DEL         0x7F

/**
 * @brief  Frontend-local output: always USART1 DMA TX, independent of the
 *         switchable cli_core output callback (used for prompt/echo/redraw).
 */
static void cli_uart_write(const char* str)
{
    bsp_usart_write_dma((const uint8_t*)str, (uint16_t)strlen(str));
}

/* ------------------------------------------------------------------ */
/* Command history (ring buffer)                                      */
/* ------------------------------------------------------------------ */

static char    s_history[CLI_HISTORY_SIZE][CLI_LINE_BUF_SIZE];
static uint8_t s_histCount = 0;   /* number of valid entries */
static uint8_t s_histHead  = 0;   /* next write position */

/**
 * @brief  Store a command line in the history ring (skips empty lines and
 *         repeats of the most recent entry).
 */
static void cli_history_add(const char* line)
{
    if (line[0] == '\0')
    {
        return;
    }
    if (s_histCount > 0)
    {
        uint8_t last = (s_histHead + CLI_HISTORY_SIZE - 1) % CLI_HISTORY_SIZE;
        if (strcmp(s_history[last], line) == 0)
        {
            return;
        }
    }
    strcpy(s_history[s_histHead], line);
    s_histHead = (s_histHead + 1) % CLI_HISTORY_SIZE;
    if (s_histCount < CLI_HISTORY_SIZE)
    {
        s_histCount++;
    }
}

/**
 * @brief  Get a history entry; nav = 0 is the newest entry.
 */
static const char* cli_history_get(int nav)
{
    int idx = ((int)s_histHead - 1 - nav + CLI_HISTORY_SIZE) % CLI_HISTORY_SIZE;
    return s_history[idx];
}

/* ------------------------------------------------------------------ */
/* Line redraw / tab completion                                       */
/* ------------------------------------------------------------------ */

/**
 * @brief  Redraw the input line: erase `shownLen` chars, print prompt + line.
 * @return new shown length
 */
static uint16_t cli_redraw_line(const char* line, uint16_t shownLen)
{
    uint16_t i;
    uint16_t len = (uint16_t)strlen(line);

    cli_uart_write("\r" CLI_PROMPT);
    for (i = 0; i < shownLen; i++)
    {
        cli_uart_write(" ");
    }
    cli_uart_write("\r" CLI_PROMPT);
    if (len > 0)
    {
        bsp_usart_write_dma((const uint8_t*)line, len);
    }
    return len;
}

/**
 * @brief  Tab completion on the first token of the line.
 *         Single match: complete it and append a space.
 *         Multiple matches: extend to the common prefix, or list candidates.
 */
static uint16_t cli_tab_complete(char* line, uint16_t len)
{
    char     common[CLI_LINE_BUF_SIZE];
    uint16_t commonLen = 0;
    int      matchCount = 0;
    uint32_t i;
    uint32_t count = cli_cmd_count();

    /* Only complete the first token (no space typed yet) */
    if (memchr(line, ' ', len) != NULL)
    {
        return len;
    }
    line[len] = '\0';

    for (i = 0; i < count; i++)
    {
        const char* name = cli_cmd_name(i);
        if (strncmp(name, line, len) == 0)
        {
            if (matchCount == 0)
            {
                strcpy(common, name);
                commonLen = (uint16_t)strlen(common);
            }
            else
            {
                /* shrink common to the shared prefix */
                while (commonLen > len && strncmp(common, name, commonLen) != 0)
                {
                    commonLen--;
                }
                common[commonLen] = '\0';
            }
            matchCount++;
        }
    }

    if (matchCount == 0)
    {
        return len;
    }

    if (matchCount == 1)
    {
        /* complete the command name + one space */
        while (len < CLI_LINE_BUF_SIZE - 1 && len < commonLen)
        {
            bsp_usart_write_dma((const uint8_t*)&common[len], 1);
            line[len] = common[len];
            len++;
        }
        if (len < CLI_LINE_BUF_SIZE - 1)
        {
            line[len] = ' ';
            len++;
            cli_uart_write(" ");
        }
        return len;
    }

    if (commonLen > len)
    {
        /* extend to the common prefix */
        while (len < CLI_LINE_BUF_SIZE - 1 && len < commonLen)
        {
            bsp_usart_write_dma((const uint8_t*)&common[len], 1);
            line[len] = common[len];
            len++;
        }
    }
    else
    {
        /* ambiguous: list the candidates and redraw */
        cli_uart_write("\r\n");
        for (i = 0; i < count; i++)
        {
            const char* name = cli_cmd_name(i);
            if (strncmp(name, line, len) == 0)
            {
                cli_uart_write(name);
                cli_uart_write("  ");
            }
        }
        cli_uart_write("\r\n");
        cli_redraw_line(line, len);
    }
    return len;
}

/**
 * @brief  CLI task: receive bytes, edit the line, dispatch on terminator.
 *         Extra keys: Ctrl+Z turns off active log printing, TAB completes
 *         the command name, UP/DOWN arrows walk the command history.
 */
static void CliTask(void* argument)
{
    static char line[CLI_LINE_BUF_SIZE];
    uint16_t len       = 0;
    uint16_t shownLen  = 0;   /* chars currently displayed after the prompt */
    uint8_t  swallow   = 0;   /* complementary terminator to swallow once */
    uint8_t  escState  = 0;   /* 0=normal, 1=got ESC, 2=got ESC '[' */
    int      histNav   = -1;  /* -1 = editing, 0.. = history entry (0=newest) */
    uint8_t  ch;
    (void)argument;

    cli_uart_write("\r\nCLI ready. Type 'help' for commands.\r\n" CLI_PROMPT);

    for (;;)
    {
        if (bsp_usart_read_byte(&ch, BSP_USART_WAIT_FOREVER) == 0)
        {
            continue;
        }

        /* Swallow the second half of a "\r\n" / "\n\r" pair */
        if (swallow != 0)
        {
            uint8_t exp = swallow;
            swallow = 0;
            if (ch == exp)
            {
                continue;
            }
        }

        /* Escape sequences (arrow keys: ESC '[' 'A'/'B') */
        if (escState == 1)
        {
            escState = (ch == '[') ? 2 : 0;
            continue;
        }
        if (escState == 2)
        {
            escState = 0;
            if (ch == 'A')          /* UP: older history entry */
            {
                if (histNav + 1 < (int)s_histCount)
                {
                    histNav++;
                    strcpy(line, cli_history_get(histNav));
                    shownLen = cli_redraw_line(line, shownLen);
                    len = (uint16_t)strlen(line);
                }
            }
            else if (ch == 'B')     /* DOWN: newer entry / back to empty line */
            {
                if (histNav >= 0)
                {
                    histNav--;
                    if (histNav >= 0)
                    {
                        strcpy(line, cli_history_get(histNav));
                    }
                    else
                    {
                        line[0] = '\0';
                    }
                    shownLen = cli_redraw_line(line, shownLen);
                    len = (uint16_t)strlen(line);
                }
            }
            /* other escape sequences are ignored */
            continue;
        }
        if (ch == CLI_KEY_ESC)
        {
            escState = 1;
            continue;
        }

        if (ch == CLI_KEY_CTRL_Z)
        {
            /* Ctrl+Z: turn off active log printing */
            AppTasks_SetLogEnabled(0);
            cli_uart_write("\r\n[log off]\r\n");
            shownLen = cli_redraw_line(line, len);
            continue;
        }

        if (ch == CLI_KEY_TAB)
        {
            bsp_usart_tx_lock();
            len = cli_tab_complete(line, len);
            shownLen = len;
            bsp_usart_tx_unlock();
            continue;
        }

        if (ch == '\r' || ch == '\n')
        {
            /* Any of "\r", "\n", "\r\n", "\n\r" terminates the line */
            swallow = (ch == '\r') ? (uint8_t)'\n' : (uint8_t)'\r';

            bsp_usart_tx_lock();
            cli_uart_write("\r\n");
            line[len] = '\0';
            cli_history_add(line);   /* copy before dispatch tokenizes in place */
            cli_set_output(NULL);    /* UART frontend: default output */
            (void)cli_exec_line(line);
            cli_uart_write(CLI_PROMPT);
            bsp_usart_tx_unlock();

            len      = 0;
            shownLen = 0;
            histNav  = -1;
        }
        else if (ch == CLI_KEY_BACKSPACE || ch == CLI_KEY_DEL)
        {
            if (len > 0)
            {
                len--;
                cli_uart_write("\b \b");
                shownLen = len;
            }
        }
        else if (ch >= 0x20 && ch < 0x7F)
        {
            if (len < CLI_LINE_BUF_SIZE - 1)
            {
                line[len++] = (char)ch;
                bsp_usart_write_dma(&ch, 1);   /* echo */
                shownLen = len;
            }
            else
            {
                cli_uart_write("\a");               /* line full: bell */
            }
        }
        /* other control characters are ignored */
    }
}

/**
 * @brief  Create the CLI task.
 */
void AppCli_Init(void)
{
    xTaskCreate(CliTask, "CLI", CLI_TASK_STACK, NULL, CLI_TASK_PRIO, NULL);
}