// A simple, vga textmode console ready to use before tty init
#include "type.h"
#include "stdio.h"
#include "const.h"
#include "protect.h"
#include "string.h"
#include "fs.h"
#include "proc.h"
#include "tty.h"
#include "console.h"
#include "global.h"
#include "keyboard.h"
#include "proto.h"
#include "x86.h"

#define INDEX(row, col) ((row)*SCR_WIDTH + (col))

static char logbuf[CON_MAX_LOGBUF];
static s_console con = {
	.row = 0,
	.col = 0,
	.buf = logbuf,
	.buf_head = 0,
	.buf_tail = 0
};

static inline void vga_put_raw(u32 pos, u16 dat)
{
	u16 *pch = (u16 *)K_PHY2LIN(V_MEM_BASE) + pos;
	*pch = dat;
}

// simple scroll, just abandon those scrolled up
static void scroll()
{
	u16* video_mem = (u16 *)K_PHY2LIN(V_MEM_BASE);
	for (int i = 0; i < SCR_HEIGHT - 1; ++ i) {
		for (int j = 0; j < SCR_WIDTH; ++ j) {
			video_mem[INDEX(i, j)] = video_mem[INDEX(i+1, j)];
		}
	}
	for (int j = 0; j < SCR_WIDTH; ++ j) {
		video_mem[INDEX(SCR_HEIGHT-1, j)] = BLANK;
	}
}

static void set_cursor(unsigned int position)
{
	outb(CRTC_ADDR_REG, CURSOR_H);
	outb(CRTC_DATA_REG, (position >> 8) & 0xFF);
	outb(CRTC_ADDR_REG, CURSOR_L);
	outb(CRTC_DATA_REG, position & 0xFF);
}

void simpleconsole_init()
{
	con.row = 0;
	con.col = 0;
	con.buf = logbuf;
	con.buf_head = 0;
	con.buf_tail = 0;
}

static void do_console_write(char ch)
{
	con.buf[con.buf_tail] = ch;
	con.buf_tail = NEXT(con.buf_tail, CON_MAX_LOGBUF);
	if (con.buf_head == con.buf_tail) con.buf_head = NEXT(con.buf_head, CON_MAX_LOGBUF);

	switch (ch)
	{
	case '\n':
		con.row ++;
		con.col = 0;
		if (con.row >= SCR_HEIGHT) {
			scroll();
			con.row --;
		}
		break;
	case '\r':
		con.col = 0;
		break;
	case '\b':
		if (con.col == 0) {
			if (con.row) con.row --;
			con.col = SCR_WIDTH - 1;
		}
		else {
			con.col --;
		}
		break;
	default:
		vga_put_raw(INDEX(con.row, con.col), MAKE_CELL(DEFAULT_CHAR_COLOR, ch));
		con.col ++;
		if (con.col >= SCR_WIDTH) {
			con.col = 0;
			con.row ++;
		}

		if (con.row >= SCR_HEIGHT) {
			scroll();
			con.row --;
		}
		break;
	}
}

void simpleconsole_write(char* buf, int nr)
{
	while (nr --) {
		do_console_write(*buf ++);
	}
	set_cursor(INDEX(con.row, con.col));
}

void simpleconsole_transfer(void (*write)(char ch))
{
	int i = con.buf_head;
	while (i != con.buf_tail) {
		write(con.buf[i]);
		i = NEXT(i, CON_MAX_LOGBUF);
	}
}

void simpleconsole_setcur(int row, int col) {
	con.row = max(0, min(row, SCR_HEIGHT-1));
	con.col = max(0, min(row, SCR_WIDTH-1));
	set_cursor(INDEX(con.row, con.col));
}