#include "vtconsole.h"
#include <stdlib.h>
#include <ctype.h>
#define min(a, b) ((a) < (b) ? (a) : (b))


/* --- Constructor/Destructor ----------------------------------------------- */

vtconsole_t *vtconsole(int width, int height, vtc_paint_handler_t on_paint, vtc_cursor_handler_t on_move)
{
    vtconsole_t *vtc = malloc(sizeof(vtconsole_t));

    vtc->width = width;
    vtc->height = height;

    vtc->ansiparser = (vtansi_parser_t){VTSTATE_ESC, {{0, 0}}, 0};
    vtc->attr = VTC_DEFAULT_ATTR;

    vtc->buffer = malloc(width * height * sizeof(vtcell_t));

    vtc->cursor = (vtcursor_t){0, 0};

    vtc->on_paint = on_paint;
    vtc->on_move = on_move;

    vtconsole_clear(vtc, 0, 0, width, height - 1);

    return vtc;
}

void vtconsole_delete(vtconsole_t *vtc)
{
    free(vtc->buffer);
    free(vtc);
}

/* --- Internal methodes ---------------------------------------------------- */

void vtconsole_clear(vtconsole_t *vtc, int fromx, int fromy, int tox, int toy)
{
    for (int i = fromx + fromy * vtc->width; i < tox + toy * vtc->width; i++)
    {
        vtcell_t *cell = &vtc->buffer[i];

        cell->attr = VTC_DEFAULT_ATTR;
        cell->c = ' ';

        if (vtc->on_paint)
        {
            vtc->on_paint(vtc, cell, i % vtc->width, i / vtc->width);
        }
    }
}

void vtconsole_scroll(vtconsole_t *vtc, int lines)
{
    if (lines == 0) return;

    lines = lines > vtc->height ? vtc->height : lines;

    // Scroll the screen by number of $lines.
    for (int i = 0; i < ((vtc->width * vtc->height) - (vtc->width * lines)); i++)
    {
        vtc->buffer[i] = vtc->buffer[i + (vtc->width * lines)];

        if (vtc->on_paint)
        {
            vtc->on_paint(vtc, &vtc->buffer[i], i % vtc->width, i / vtc->width);
        }
    }

    // Clear the last $lines.
    for (int i = ((vtc->width * vtc->height) - (vtc->width * lines)); i < vtc->width * vtc->height; i++)
    {
        vtcell_t *cell = &vtc->buffer[i];
        cell->attr = VTC_DEFAULT_ATTR;
        cell->c = ' ';

        if (vtc->on_paint)
        {
            vtc->on_paint(vtc, &vtc->buffer[i], i % vtc->width, i / vtc->width);
        }
    }

    // Move the cursor up $lines
    if (vtc->cursor.y > 0)
    {
        vtc->cursor.y -= lines;

        if (vtc->cursor.y < 0) vtc->cursor.y = 0;

        if (vtc->on_move)
        {
            vtc->on_move(vtc, &vtc->cursor);
        }
    }
}

// Append a new line
void vtconsole_newline(vtconsole_t *vtc)
{
    vtc->cursor.x = 0;
    vtc->cursor.y++;

    if (vtc->cursor.y == vtc->height)
    {
        vtconsole_scroll(vtc, 1);
    }

    if (vtc->on_move)
    {
        vtc->on_move(vtc, &vtc->cursor);
    }
}

// Append character to the console buffer.
void vtconsole_append(vtconsole_t *vtc, char c)
{
    if (c == '\n')
    {
        vtconsole_newline(vtc);
    }
    else if (c == '\r')
    {
        vtc->cursor.x = 0;

        if (vtc->on_move)
        {
            vtc->on_move(vtc, &vtc->cursor);
        }
    }
    else if (c == '\t')
    {
        int n = 8 - (vtc->cursor.x % 8);

        for (int i = 0; i < n; i++)
        {
            vtconsole_append(vtc, ' ');
        }
    }
    else if (c == '\b')
    {
        if (vtc->cursor.x > 0)
        {
            vtc->cursor.x--;
        }
        else
        {
            vtc->cursor.y--;
            vtc->cursor.x = vtc->width - 1;
        }

        if (vtc->on_move)
        {
            vtc->on_move(vtc, &vtc->cursor);
        }
    }
    else
    {
        if (vtc->cursor.x >= vtc->width)
            vtconsole_newline(vtc);

        vtcell_t *cell = &vtc->buffer[vtc->cursor.x + vtc->cursor.y * vtc->width];
        cell->c = c;
        cell->attr = vtc->attr;

        if (vtc->on_paint)
        {
            vtc->on_paint(vtc, cell, vtc->cursor.x, vtc->cursor.y);
        }

        vtc->cursor.x++;

        if (vtc->on_move)
        {
            vtc->on_move(vtc, &vtc->cursor);
        }
    }
}

// Moves the cursor to row n, column m. The values are 1-based,
void vtconsole_csi_cup(vtconsole_t *vtc, vtansi_arg_t *stack, int count)
{
    if (count == 1 && stack[0].empty)
    {
        vtc->cursor.x = 0;
        vtc->cursor.y = 0;
    }
    else if (count == 2)
    {
        if (stack[0].empty)
        {
            vtc->cursor.y = 0;
        }
        else
        {
            vtc->cursor.y = min(stack[0].value - 1, vtc->height - 1);
        }

        if (stack[1].empty)
        {
            vtc->cursor.y = 0;
        }
        else
        {
            vtc->cursor.x = min(stack[1].value - 1, vtc->width - 1);
        }
    }

    if (vtc->on_move)
    {
        vtc->on_move(vtc, &vtc->cursor);
    }
}

// Clears part of the screen.
void vtconsole_csi_ed(vtconsole_t *vtc, vtansi_arg_t *stack, int count)
{
    (void)(count);

    vtcursor_t cursor = vtc->cursor;

    if (stack[0].empty)
    {
        vtconsole_clear(vtc, cursor.x, cursor.y, vtc->width, vtc->height - 1);
    }
    else
    {
        int attr = stack[0].value;

        if (attr == 0)
            vtconsole_clear(vtc, cursor.x, cursor.y, vtc->width, vtc->height - 1);
        else if (attr == 1)
            vtconsole_clear(vtc, 0, 0, cursor.x, cursor.y);
        else if (attr == 2)
            vtconsole_clear(vtc, 0, 0, vtc->width, vtc->height - 1);
    }
}

// Erases part of the line.
void vtconsole_csi_el(vtconsole_t *vtc, vtansi_arg_t *stack, int count)
{
    (void)(count);

    vtcursor_t cursor = vtc->cursor;

    if (stack[0].empty)
    {
        vtconsole_clear(vtc, cursor.x, cursor.y, vtc->width, cursor.y);
    }
    else
    {
        int attr = stack[0].value;

        if (attr == 0)
            vtconsole_clear(vtc, cursor.x, cursor.y, vtc->width, cursor.y);
        else if (attr == 1)
            vtconsole_clear(vtc, 0, cursor.y, cursor.x, cursor.y);
        else if (attr == 2)
            vtconsole_clear(vtc, 0, cursor.y, vtc->width, cursor.y);
    }
}

// Sets the appearance of the following characters
void vtconsole_csi_sgr(vtconsole_t *vtc, vtansi_arg_t *stack, int count)
{
    for (int i = 0; i < count; i++)
    {
        if (stack[i].empty || stack[i].value == 0)
        {
            vtc->attr = VTC_DEFAULT_ATTR;
        }
        else
        {
            int attr = stack[i].value;

            if (attr == 1) // Increased intensity
            {
                vtc->attr.bright = true;
            }
            else if (attr >= 30 && attr <= 37) // Set foreground color
            {
                vtc->attr.fg = attr - 30;
            }
            else if (attr >= 40 && attr <= 47) // Set background color
            {
                vtc->attr.bg = attr - 40;
            }
        }
    }
}

// Process ANSI escape sequences and append character to the console buffer.
void vtconsole_process(vtconsole_t *vtc, char c)
{
    vtansi_parser_t *parser = &vtc->ansiparser;

    switch (parser->state)
    {
    case VTSTATE_ESC:
        if (c == '\033')
        {
            parser->state = VTSTATE_BRACKET;

            parser->index = 0;

            parser->stack[parser->index].value = 0;
            parser->stack[parser->index].empty = true;
        }
        else
        {
            parser->state = VTSTATE_ESC;
            vtconsole_append(vtc, c);
        }
        break;

    case VTSTATE_BRACKET:
        if (c == '[')
        {
            parser->state = VTSTATE_ATTR;
        }
        else
        {
            parser->state = VTSTATE_ESC;
            vtconsole_append(vtc, c);
        }
        break;
    case VTSTATE_ATTR:
        if (isdigit(c))
        {
            parser->stack[parser->index].value *= 10;
            parser->stack[parser->index].value += (c - '0');
            parser->stack[parser->index].empty = false;
        }
        else
        {
            if ((parser->index) < VTC_ANSI_PARSER_STACK_SIZE)
            {
                parser->index++;
            }

            parser->stack[parser->index].value = 0;
            parser->stack[parser->index].empty = true;

            parser->state = VTSTATE_ENDVAL;
        }
        break;
    default:
        break;
    }

    if (parser->state == VTSTATE_ENDVAL)
    {
        if (c == ';')
        {
            parser->state = VTSTATE_ATTR;
        }
        else
        {
            switch (c)
            {
            case 'A':
                /* Cursor up P1 rows */
                break;
            case 'B':
                /* Cursor down P1 rows */
                break;

            case 'C':
                /* Cursor right P1 columns */
                break;
            case 'D':
                /* Cursor left P1 columns */
                break;

            case 'E':
                /* Cursor to first column of line P1 rows down from current */
                break;
            case 'F':
                /* Cursor to first column of line P1 rows up from current */
                break;

            case 'G':
                /* Cursor to column P1 */
                break;
            case 'd':
                /* Cursor left P1 columns */
                break;

            case 'H':
                vtconsole_csi_cup(vtc, parser->stack, parser->index);
                break;
            case 'J':
                vtconsole_csi_ed(vtc, parser->stack, parser->index);
                break;
            case 'K':
                vtconsole_csi_el(vtc, parser->stack, parser->index);
                break;
            case 'm':
                vtconsole_csi_sgr(vtc, parser->stack, parser->index);
                break;
            }

            parser->state = VTSTATE_ESC;
        }
    }
}

/* --- Methodes ------------------------------------------------------------- */

void vtconsole_putchar(vtconsole_t *vtc, char c)
{
    vtconsole_process(vtc, c);
}

void vtconsole_write(vtconsole_t *vtc, const char *buffer, unsigned int size)
{
    for (unsigned int i = 0; i < size; i++)
    {
        vtconsole_process(vtc, buffer[i]);
    }
}