///                          _             _
/// __  _____ _ __ _ __ ___ (_)_ __   __ _| |
/// \ \/ / _ \ '__| '_ ` _ \| | '_ \ / _` | |
///  >  <  __/ |  | | | | | | | | | | (_| | |
/// /_/\_\___|_|  |_| |_| |_|_|_| |_|\__,_|_|
///
/// Copyright (c) 1997 - Ognjen 'xolatile' Milan Robovic
///
/// xolatile@chud.cyou - xerminal - Library containing the full power of VT100 escape sequences or something for TUI programs.
///
/// This program is free software, free as in freedom and as in free beer, you can redistribute it and/or modify it under the terms of the GNU
/// General Public License as published by the Free Software Foundation, either version 3 of the License, or any later version if you wish...
///
/// This program is distributed in the hope that it will be useful, but it is probably not, and without any warranty, without even the implied
/// warranty of merchantability or fitness for a particular purpose, because it is pointless. Please see the GNU (Geenoo) General Public License
/// for more details, if you dare, it is a lot of text that nobody wants to read...

#include <termios.h>
#include <sys/ioctl.h>

#define terminal_format_length (sizeof ("\033[-;3-m-\033[0m") - 1)
#define terminal_revert_length (sizeof ("\033[H")             - 1)
#define terminal_cursor_length (sizeof ("\033[---;---H")      - 1)

typedef struct {
	char * screen;
	uint   screen_width;
	uint   screen_height;

	char format [terminal_format_length + 1];
	char cursor [terminal_cursor_length + 1];

	bool active;
	bool signal [signal_count];

	uint character;

	struct termios * old_terminal;
	struct termios * new_terminal;
} terminal_structure;

static char * terminal_screen_offset (terminal_structure * terminal, uint x, uint y) {
	return (& terminal->screen [terminal_revert_length + terminal_format_length * (y * terminal->screen_width + x) + 2 * y]);
}

static uint terminal_screen_length (terminal_structure * terminal) {
	uint constant = terminal_revert_length + terminal_cursor_length + 1;
	uint variable = terminal_format_length * terminal->screen_height * terminal->screen_width;
	uint new_line = 2 * (terminal->screen_height - 1);

	return (constant + variable + new_line);
}

static void terminal_screen_dimensions (terminal_structure * terminal) {
	struct winsize screen_dimension = { 0 };

	uint old_width  = terminal->screen_width;
	uint old_height = terminal->screen_height;

	int status = ioctl (STDOUT_FILENO, TIOCGWINSZ, & screen_dimension);

	fatal_failure (status == -1, "ioctl: Failed to get dimensions.");

	terminal->screen_width  = screen_dimension.ws_col;
	terminal->screen_height = screen_dimension.ws_row;

	if ((old_width != terminal->screen_width) || (old_height != terminal->screen_height)) {
		if (terminal->screen != null) {
			terminal->screen = deallocate (terminal->screen);
		}

		terminal->screen = allocate (terminal_screen_length (terminal));
	}

	string_copy (& terminal->screen [0], "\033[H");

	for (uint index = 0; index < terminal->screen_height - 1; ++index) {
		string_copy (& terminal->screen [terminal_revert_length + index * terminal_format_length * terminal->screen_width], "\r\n");
	}
}

static char * terminal_format_character (terminal_structure * terminal, char character, int colour, int effect) {
	if (character_is_visible (character) == false) {
		character = ' ';
	}

	colour %= colour_count;
	effect %= effect_count;

	terminal->format [2] = (char) effect + '0';
	terminal->format [5] = (char) colour + '0';
	terminal->format [7] = character;

	return (terminal->format);
}

static terminal_structure * terminal_initialize (void) {
	terminal_structure * terminal = allocate (sizeof (* terminal));

	int status = -1;

	string_copy_limit (terminal->format, "\033[-;3-m-\033[0m", terminal_format_length + 1);
	string_copy_limit (terminal->cursor, "\033[---;---H",      terminal_cursor_length + 1);

	terminal->old_terminal = allocate (sizeof (* terminal->old_terminal));
	terminal->new_terminal = allocate (sizeof (* terminal->new_terminal));

	terminal_screen_dimensions (terminal);

	status = tcgetattr (STDIN_FILENO, terminal->old_terminal);

	fatal_failure (status == -1, "tcgetattr: Failed to get default attributes.");

	memory_copy (terminal->new_terminal, terminal->old_terminal, sizeof (* terminal->old_terminal));

	terminal->new_terminal->c_cc [VMIN]  = (uchar) 0;
	terminal->new_terminal->c_cc [VTIME] = (uchar) 1;

	terminal->new_terminal->c_iflag &= (uint) ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
	terminal->new_terminal->c_oflag &= (uint) ~(OPOST);
	terminal->new_terminal->c_cflag |= (uint)  (CS8);
	terminal->new_terminal->c_lflag &= (uint) ~(ECHO | ICANON | IEXTEN | ISIG);

	status = tcsetattr (STDIN_FILENO, TCSAFLUSH, terminal->new_terminal);

	fatal_failure (status == -1, "tcsetattr: Failed to set reverse attributes.");

	terminal->active = true;

	show_cursor (false);

	echo_clear ();

	return (terminal);
}

static terminal_structure * terminal_deinitialize (terminal_structure * terminal) {
	int status = tcsetattr (STDIN_FILENO, TCSAFLUSH, terminal->old_terminal);

	fatal_failure (status == -1, "tcsetattr: Failed to set default attributes.");

	terminal->screen       = deallocate (terminal->screen);
	terminal->old_terminal = deallocate (terminal->old_terminal);
	terminal->new_terminal = deallocate (terminal->new_terminal);

	echo_clear ();

	show_cursor (true);

	return (deallocate (terminal));
}

static void terminal_synchronize (terminal_structure * terminal) {
	uint character = 0;

	output (terminal->screen, terminal_screen_length (terminal));

	terminal_screen_dimensions (terminal);

	for (uint index = 0; index < signal_count; ++index) {
		terminal->signal [index] = false;
	}

	input (& character, sizeof (character));

	terminal->character = (uint) character;

	if (character == 0x0000001b) {
		terminal->signal [signal_escape] = true;
	} else if (character == 0x00415b1b) {
		terminal->signal [signal_arrow_up] = true;
	} else if (character == 0x00425b1b) {
		terminal->signal [signal_arrow_down] = true;
	} else if (character == 0x00435b1b) {
		terminal->signal [signal_arrow_right] = true;
	} else if (character == 0x00445b1b) {
		terminal->signal [signal_arrow_left] = true;
	} else if (character == 0x00000020) {
		terminal->signal [signal_space] = true;
	} else if (character == 0x0000007f) {
		terminal->signal [signal_backspace] = true;
	} else if (character == 0x0000000d) {
		terminal->signal [signal_return] = true;
	} else if (character_is_digit ((char) character) == true) {
		terminal->signal [signal_0 + character - '0'] = true;
	} else if (character_is_lowercase ((char) character) == true) {
		terminal->signal [signal_a + character - 'a'] = true;
	} else if (character_is_uppercase ((char) character) == true) {
		terminal->signal [signal_a + character - 'A'] = true;
		terminal->signal [signal_left_shift]  = true;
		terminal->signal [signal_right_shift] = true;
	}
}

static void terminal_render_cursor (terminal_structure * terminal, uint x, uint y) { /* BROKE IT INTENTIONALLY */
	string_copy_limit (terminal->cursor + 2, string_align_left (number_to_string (y % 1000 + 1), 3, '0'), 3);
	string_copy_limit (terminal->cursor + 6, string_align_left (number_to_string (x % 1000 + 1), 3, '0'), 3);

	string_copy_limit (& terminal->screen [terminal_screen_length (terminal) - terminal_cursor_length - 1], terminal->cursor, terminal_cursor_length);
}

static void terminal_render_character (terminal_structure * terminal, char character, uint colour, uint effect, uint x, uint y) {
	if ((x >= terminal->screen_width) || (y >= terminal->screen_height)) {
		return;
	}

	string_copy_limit (terminal_screen_offset (terminal, x, y), terminal_format_character (terminal, character, colour, effect), terminal_format_length);
}

static void terminal_render_toggle (terminal_structure * terminal, bool toggle, uint x, uint y) {
	char marker = (toggle == true) ? '+'          : '-';
	char colour = (toggle == true) ? colour_green : colour_red;

	terminal_render_character (terminal, '[',    colour_grey, effect_bold, x + 0, y);
	terminal_render_character (terminal, marker, colour,      effect_bold, x + 1, y);
	terminal_render_character (terminal, ']',    colour_grey, effect_bold, x + 2, y);
}

static void terminal_render_fill_bar (terminal_structure * terminal, uint value, uint limit, char character, uint colour, uint effect, uint x, uint y) {
	terminal_render_character (terminal, '[', colour_grey, effect_bold, x,             y);
	terminal_render_character (terminal, ']', colour_grey, effect_bold, x + limit + 1, y);

	for (uint index = 0; index < limit; ++index) {
		terminal_render_character (terminal, (index < value) ? character : ' ', colour, effect, x + index + 1, y);
	}
}

static void terminal_render_string (terminal_structure * terminal, char * string, uint colour, uint effect, uint x, uint y) {
	for (uint index = 0; string [index] != '\0'; ++index) {
		terminal_render_character (terminal, string [index], colour, effect, x + index, y);
	}
}

static void terminal_render_number (terminal_structure * terminal, int number, uint colour, uint effect, uint x, uint y) {
	terminal_render_string (terminal, number_to_string (number), colour, effect, x, y);
}

static void terminal_render_string_crop (terminal_structure * terminal, char * string, uint colour, uint effect, uint x, uint y, uint crop) {
	for (uint index = 0; (string [index] != '\0') && (index < crop); ++index) {
		terminal_render_character (terminal, string [index], colour, effect, x + index, y);
	}
}

static void terminal_render_number_crop (terminal_structure * terminal, int number, uint colour, uint effect, uint x, uint y, uint crop) {
	terminal_render_string_crop (terminal, number_to_string (number), colour, effect, x, y, crop);
}

static void terminal_render_vertical_line (terminal_structure * terminal, char character, uint colour, uint effect, uint x, uint y, uint height) {
	for (uint offset = 0; offset != height; ++offset) {
		terminal_render_character (terminal, character, colour, effect, x, y + offset);
	}
}

static void terminal_render_horizontal_line (terminal_structure * terminal, char character, uint colour, uint effect, uint x, uint y, uint width) {
	for (uint offset = 0; offset != width; ++offset) {
		terminal_render_character (terminal, character, colour, effect, x + offset, y);
	}
}

static void terminal_render_rectangle_line (terminal_structure * terminal, char character, uint colour, uint effect, uint x, uint y, uint width, uint height) {
	terminal_render_vertical_line   (terminal, character, colour, effect, x + 0,         y + 0,          height + 0);
	terminal_render_vertical_line   (terminal, character, colour, effect, x + width - 1, y + 0,          height + 0);
	terminal_render_horizontal_line (terminal, character, colour, effect, x + 1,         y + 0,          width  - 1);
	terminal_render_horizontal_line (terminal, character, colour, effect, x + 1,         y + height - 1, width  - 1);
}

static void terminal_render_rectangle_fill (terminal_structure * terminal, char character, uint colour, uint effect, uint x, uint y, uint width, uint height) {
	for (uint offset_y = 0; offset_y != height; ++offset_y) {
		for (uint offset_x = 0; offset_x != width; ++offset_x) {
			terminal_render_character (terminal, character, colour, effect, x + offset_x, y + offset_y);
		}
	}
}

static void terminal_render_background (terminal_structure * terminal, char character, uint colour, uint effect) {
	for (uint y = 0; y != terminal->screen_height; ++y) {
		for (uint x = 0; x != terminal->screen_width; ++x) {
			terminal_render_character (terminal, character, colour, effect, x, y);
		}
	}
}

static void terminal_render_format (terminal_structure * terminal, char * format, uint x, uint y, ...) {
	va_list list;

	uint offset_x = 0;
	uint offset_y = 0;

	colour_enumeration colour = colour_white;
	effect_enumeration effect = effect_normal;

	va_start (list, format);

	for (; * format != character_null; ++format) {
		switch (* format) {
			case ('\t'): {
				offset_x += 8;
			} break;
			case ('\n'): {
				offset_x *= 0;
				offset_y += 1;
			} break;
			case ('\r'): {
				offset_x *= 0;
			} break;
			case ('%'): {
				++format;
				switch (* format) {
					case ('%'): {
						terminal_render_character (terminal, '%', colour, effect, x + offset_x, y + offset_y);
						++offset_x;
					} break;
					case ('i'): {
						char * number = number_to_string (va_arg (list, int));
						terminal_render_string (terminal, number, colour, effect, x + offset_x, y + offset_y);
						offset_x += string_length (number);
					} break;
					case ('t'): {
						bool toggle = (bool) va_arg (list, int);
						terminal_render_toggle (terminal, toggle, x + offset_x, y + offset_y);
						offset_x += 3;
					} break;
					case ('b'): {
						bool boolean = (bool) va_arg (list, int);
						terminal_render_string (terminal, (boolean == true) ? "true" : "false", colour, effect, x + offset_x, y + offset_y);
						offset_x += (boolean == true) ? 4 : 5;
					} break;
					case ('c'): {
						char character = (char) va_arg (list, int);
						terminal_render_character (terminal, character, colour, effect, x + offset_x, y + offset_y);
						++offset_x;
					} break;
					case ('s'): {
						char * string = va_arg (list, char *);
						terminal_render_string (terminal, string, colour, effect, x + offset_x, y + offset_y);
						offset_x += string_length (string);
					} break;
					default: {
						terminal_render_character (terminal, '?', colour, effect, x + offset_x, y + offset_y);
						++offset_x;
					} break;
				}
			} break;
			case ('/'): {
				++format;
				switch (* format) {
					case ('/'): {
						terminal_render_character (terminal, '/', colour, effect, x + offset_x, y + offset_y);
						++offset_x;
					} break;
					case ('A'): effect = effect_normal;         break;
					case ('B'): effect = effect_bold;           break;
					case ('C'): effect = effect_italic;         break;
					case ('D'): effect = effect_undefined_code; break;
					case ('E'): effect = effect_underline;      break;
					case ('F'): effect = effect_blink;          break;
					case ('G'): effect = effect_reverse;        break;
					case ('H'): effect = effect_invisible_text; break;
					case ('0'): colour = colour_grey;           break;
					case ('1'): colour = colour_red;            break;
					case ('2'): colour = colour_green;          break;
					case ('3'): colour = colour_yellow;         break;
					case ('4'): colour = colour_blue;           break;
					case ('5'): colour = colour_pink;           break;
					case ('6'): colour = colour_cyan;           break;
					case ('7'): colour = colour_white;          break;
					case ('-'): {
						colour = colour_white;
						effect = effect_normal;
					} break;
					default: {
						terminal_render_character (terminal, '?', colour, effect, x + offset_x, y + offset_y);
						++offset_x;
					} break;
				}
			} break;
			default: {
				terminal_render_character (terminal, * format, colour, effect, x + offset_x, y + offset_y);
				++offset_x;
			} break;
		}
	}

	va_end (list);
}

#undef terminal_format_length
#undef terminal_revert_length
#undef terminal_cursor_length