/* Copyright (C) 2018  June McEnroe <june@causal.agency>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#define _XOPEN_SOURCE_EXTENDED

#include <assert.h>
#include <curses.h>
#include <err.h>
#include <errno.h>
#include <locale.h>
#include <poll.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sysexits.h>
#include <unistd.h>
#include <wchar.h>

#include "torus.h"
#include "help.h"

#define err(...) do { endwin(); err(__VA_ARGS__); } while(0)
#define errx(...) do { endwin(); errx(__VA_ARGS__); } while (0)

#define DIV_ROUND(a, b) (((a) + (b) / 2) / (b))

#define CTRL(ch) ((ch) ^ 0x40)
enum {
	Esc = 0x1B,
	Del = 0x7F,
};

static uint32_t log2(uint32_t n) {
	assert(n > 0);
	return 32 - __builtin_clz(n) - 1;
}

static void curse(void) {
	setlocale(LC_CTYPE, "");

	initscr();
	start_color();
	if (!has_colors() || COLOR_PAIRS < 64) {
		endwin();
		fprintf(stderr, "Sorry, your terminal doesn't support colors!\n");
		fprintf(stderr, "If you think it should, check TERM.\n");
		exit(EX_CONFIG);
	}
	if (LINES < CellRows || COLS < CellCols) {
		endwin();
		fprintf(
			stderr,
			"Sorry, your terminal is too small!\n"
			"It must be at least %ux%u characters.\n",
			CellCols, CellRows
		);
		exit(EX_CONFIG);
	}

	assume_default_colors(0, 0);
	if (COLORS >= 16) {
		for (short pair = 1; pair < 0x80; ++pair) {
			init_pair(pair, pair & 0x0F, (pair & 0xF0) >> 4);
		}
	} else {
		for (short pair = 1; pair < 0100; ++pair) {
			init_pair(pair, pair & 007, (pair & 070) >> 3);
		}
	}

	color_set(ColorWhite, NULL);
	bool hline = (LINES > CellRows);
	bool vline = (COLS > CellCols);
	if (hline) mvhline(CellRows, 0, 0, CellCols);
	if (vline) mvvline(0, CellCols, 0, CellRows);
	if (hline && vline) mvaddch(CellRows, CellCols, ACS_LRCORNER);
	color_set(0, NULL);

	cbreak();
	noecho();
	keypad(stdscr, true);
	set_escdelay(100);
}

static attr_t colorAttr(uint8_t color) {
	if (COLORS >= 16) return A_NORMAL;
	return (color & ColorBright) ? A_BOLD : A_NORMAL;
}
static short colorPair(uint8_t color) {
	if (COLORS >= 16) return color;
	return (color & 0x70) >> 1 | (color & 0x07);
}

static void drawCell(
	const struct Tile *tile, uint8_t cellX, uint8_t cellY, attr_t attr
) {
	uint8_t color = tile->colors[cellY][cellX];
	uint8_t cell = tile->cells[cellY][cellX];

	cchar_t cch;
	wchar_t wch[] = { CP437[cell], L'\0' };
	setcchar(&cch, wch, attr | colorAttr(color), colorPair(color), NULL);
	mvadd_wch(cellY, cellX, &cch);
}

static void drawTile(const struct Tile *tile) {
	for (uint8_t cellY = 0; cellY < CellRows; ++cellY) {
		for (uint8_t cellX = 0; cellX < CellCols; ++cellX) {
			drawCell(tile, cellX, cellY, A_NORMAL);
		}
	}
}

static int client;

static uint8_t cellX;
static uint8_t cellY;
static struct Tile tile;

static void serverTile(void) {
	ssize_t size = recv(client, &tile, sizeof(tile), 0);
	if (size < 0) err(EX_IOERR, "recv");
	if ((size_t)size < sizeof(tile)) errx(EX_PROTOCOL, "truncated tile");
	drawTile(&tile);
}

static void serverMove(struct ServerMessage msg) {
	cellX = msg.move.cellX;
	cellY = msg.move.cellY;
}

static void serverPut(struct ServerMessage msg) {
	tile.colors[msg.put.cellY][msg.put.cellX] = msg.put.color;
	tile.cells[msg.put.cellY][msg.put.cellX] = msg.put.cell;
	drawCell(&tile, msg.put.cellX, msg.put.cellY, A_NORMAL);
}

static void serverCursor(struct ServerMessage msg) {
	if (msg.cursor.oldCellX != CursorNone) {
		drawCell(&tile, msg.cursor.oldCellX, msg.cursor.oldCellY, A_NORMAL);
	}
	if (msg.cursor.newCellX != CursorNone) {
		drawCell(&tile, msg.cursor.newCellX, msg.cursor.newCellY, A_REVERSE);
	}
}

static const uint8_t MapX = (CellCols / 2) - (3 * MapCols / 2);
static const uint8_t MapY = (CellRows / 2) - (MapRows / 2);

static const wchar_t MapCells[5] = L" ░▒▓█";
static const uint8_t MapColors[] = {
	ColorBlue, ColorCyan, ColorGreen, ColorYellow, ColorRed,
};

static void serverMap(void) {
	int t = MapY - 1;
	int l = MapX - 1;
	int b = MapY + MapRows;
	int r = MapX + 3 * MapCols;
	color_set(colorPair(ColorWhite), NULL);
	mvhline(t, MapX, ACS_HLINE, 3 * MapCols);
	mvhline(b, MapX, ACS_HLINE, 3 * MapCols);
	mvvline(MapY, l, ACS_VLINE, MapRows);
	mvvline(MapY, r, ACS_VLINE, MapRows);
	mvaddch(t, l, ACS_ULCORNER);
	mvaddch(t, r, ACS_URCORNER);
	mvaddch(b, l, ACS_LLCORNER);
	mvaddch(b, r, ACS_LRCORNER);
	color_set(0, NULL);

	struct Map map;
	ssize_t size = recv(client, &map, sizeof(map), 0);
	if (size < 0) err(EX_IOERR, "recv");
	if ((size_t)size < sizeof(map)) errx(EX_PROTOCOL, "truncated map");

	if (0 == map.max.modifyCount) return;
	if (0 == map.now - map.min.createTime) return;

	for (uint8_t y = 0; y < MapRows; ++y) {
		for (uint8_t x = 0; x < MapCols; ++x) {
			struct Meta meta = map.meta[y][x];

			uint32_t count = 0;
			if (meta.modifyCount && log2(map.max.modifyCount)) {
				count = DIV_ROUND(
					(ARRAY_LEN(MapCells) - 1) * log2(meta.modifyCount),
					log2(map.max.modifyCount)
				);
			}
			uint32_t time = 0;
			if (meta.modifyTime) {
				uint32_t modify = meta.modifyTime - map.min.createTime;
				time = DIV_ROUND(
					(ARRAY_LEN(MapColors) - 1) * modify,
					map.now - map.min.createTime
				);
			}

			wchar_t cell = MapCells[count];
			uint8_t color = MapColors[time];
			wchar_t tile[] = { cell, cell, cell, L'\0' };
			if (y == MapRows / 2 && x == MapCols / 2) tile[1] = L'⌂';
			attr_set(colorAttr(color), colorPair(color), NULL);
			mvaddwstr(MapY + y, MapX + 3 * x, tile);
		}
	}
	attr_set(A_NORMAL, 0, NULL);
}

static void readMessage(void) {
	struct ServerMessage msg;
	ssize_t size = recv(client, &msg, sizeof(msg), 0);
	if (size < 0) err(EX_IOERR, "recv");
	if ((size_t)size < sizeof(msg)) errx(EX_PROTOCOL, "truncated message");

	switch (msg.type) {
		break; case ServerTile:   serverTile();
		break; case ServerMove:   serverMove(msg);
		break; case ServerPut:    serverPut(msg);
		break; case ServerCursor: serverCursor(msg);
		break; case ServerMap:    serverMap();
		break; default: errx(EX_PROTOCOL, "unknown message type %d", msg.type);
	}
	move(cellY, cellX);
}

static void clientMessage(struct ClientMessage msg) {
	ssize_t size = send(client, &msg, sizeof(msg), 0);
	if (size < 0) err(EX_IOERR, "send");
}

static void clientMove(int8_t dx, int8_t dy) {
	struct ClientMessage msg = {
		.type = ClientMove,
		.move = { .dx = dx, .dy = dy },
	};
	clientMessage(msg);
}

static void clientPut(uint8_t color, uint8_t cell) {
	struct ClientMessage msg = {
		.type = ClientPut,
		.put = { .color = color, .cell = cell },
	};
	clientMessage(msg);
}

static void clientMap(void) {
	struct ClientMessage msg = { .type = ClientMap };
	clientMessage(msg);
}

static void clientTele(uint8_t port) {
	struct ClientMessage msg = { .type = ClientTele, .port = port };
	clientMessage(msg);
}

static struct {
	enum {
		ModeNormal,
		ModeHelp,
		ModeMap,
		ModeDirection,
		ModeInsert,
		ModeReplace,
		ModeDraw,
		ModeLine,
	} mode;
	int8_t delta;
	uint8_t color;
	uint8_t shift;
	uint8_t draw;
} input = {
	.delta = 1,
	.color = ColorWhite,
};

static struct {
	uint8_t color;
	uint8_t cell;
} copy;

static struct {
	int8_t dx;
	int8_t dy;
	uint8_t len;
} insert;

static void modeNormal(void) {
	curs_set(1);
	move(cellY, cellX);
	input.mode = ModeNormal;
}
static void modeHelp(void) {
	curs_set(0);
	drawTile(Help);
	input.mode = ModeHelp;
}
static void modeMap(void) {
	curs_set(0);
	clientMap();
	input.mode = ModeMap;
}
static void modeDirection(void) {
	input.mode = ModeDirection;
}
static void modeInsert(int8_t dx, int8_t dy) {
	insert.dx = dx;
	insert.dy = dy;
	insert.len = 0;
	input.mode = ModeInsert;
}
static void modeReplace(void) {
	input.mode = ModeReplace;
}
static void modeDraw(void) {
	input.draw = 0;
	input.mode = ModeDraw;
}
static void modeLine(void) {
	input.mode = ModeLine;
}

static void colorFg(uint8_t fg) {
	input.color = (input.color & 0x78) | (fg & 0x07);
}
static void colorBg(uint8_t bg) {
	input.color = (input.color & 0x0F) | (bg & 0x07) << 4;
}

static uint8_t colorInvert(uint8_t color) {
	return (color & 0x08)
		| (color & 0x70) >> 4
		| (color & 0x07) << 4;
}

static void cellCopy(void) {
	copy.color = tile.colors[cellY][cellX];
	copy.cell = tile.cells[cellY][cellX];
}

static void cellSwap(int8_t dx, int8_t dy) {
	if ((uint8_t)(cellX + dx) >= CellCols) return;
	if ((uint8_t)(cellY + dy) >= CellRows) return;

	uint8_t aColor = tile.colors[cellY][cellX];
	uint8_t aCell = tile.cells[cellY][cellX];

	uint8_t bColor = tile.colors[cellY + dy][cellX + dx];
	uint8_t bCell = tile.cells[cellY + dy][cellX + dx];

	clientPut(bColor, bCell);
	clientMove(dx, dy);
	clientPut(aColor, aCell);
}

static uint8_t inputCell(wchar_t ch) {
	if (ch == ' ') return ' ';
	if (ch < 0x80) return (uint8_t)ch + input.shift;
	for (size_t i = 0; i < ARRAY_LEN(CP437); ++i) {
		if (ch == CP437[i]) return i;
	}
	return 0;
}

static void inputNormal(bool keyCode, wchar_t ch) {
	if (keyCode) {
		switch (ch) {
			break; case KEY_LEFT:  clientMove(-input.delta,  0);
			break; case KEY_RIGHT: clientMove( input.delta,  0);
			break; case KEY_UP:    clientMove( 0, -input.delta);
			break; case KEY_DOWN:  clientMove( 0,  input.delta);

			break; case KEY_F(1): input.shift = 0x00;
			break; case KEY_F(2): input.shift = 0xC0;
			break; case KEY_F(3): input.shift = 0xA0;
			break; case KEY_F(4): input.shift = 0x70;
			break; case KEY_F(5): input.shift = 0x40;
		}
		return;
	}

	switch (ch) {
		break; case CTRL('L'): clearok(curscr, true);

		break; case Esc: modeNormal(); input.shift = 0;
		break; case 'q': endwin(); exit(EX_OK);

		break; case 'Q': clientTele(input.color % ARRAY_LEN(Ports));

		break; case '\\': input.delta = (input.delta == 1 ? 4 : 1);

		break; case 'h': clientMove(-input.delta,  0);
		break; case 'l': clientMove( input.delta,  0);
		break; case 'k': clientMove( 0, -input.delta);
		break; case 'j': clientMove( 0,  input.delta);
		break; case 'y': clientMove(-input.delta, -input.delta);
		break; case 'u': clientMove( input.delta, -input.delta);
		break; case 'b': clientMove(-input.delta,  input.delta);
		break; case 'n': clientMove( input.delta,  input.delta);

		break; case '0': colorFg(ColorBlack);
		break; case '1': colorFg(ColorRed);
		break; case '2': colorFg(ColorGreen);
		break; case '3': colorFg(ColorYellow);
		break; case '4': colorFg(ColorBlue);
		break; case '5': colorFg(ColorMagenta);
		break; case '6': colorFg(ColorCyan);
		break; case '7': colorFg(ColorWhite);

		break; case ')': colorBg(ColorBlack);
		break; case '!': colorBg(ColorRed);
		break; case '@': colorBg(ColorGreen);
		break; case '#': colorBg(ColorYellow);
		break; case '$': colorBg(ColorBlue);
		break; case '%': colorBg(ColorMagenta);
		break; case '^': colorBg(ColorCyan);
		break; case '&': colorBg(ColorWhite);

		break; case '8': input.color ^= ColorBright;
		break; case '9': input.color = colorInvert(input.color);
		break; case '`': input.color = tile.colors[cellY][cellX];

		break; case 'H': cellSwap(-1,  0);
		break; case 'L': cellSwap( 1,  0);
		break; case 'K': cellSwap( 0, -1);
		break; case 'J': cellSwap( 0,  1);
		break; case 'Y': cellSwap(-1, -1);
		break; case 'U': cellSwap( 1, -1);
		break; case 'B': cellSwap(-1,  1);
		break; case 'N': cellSwap( 1,  1);

		break; case 's': cellCopy();
		break; case 'x': cellCopy(); clientPut(copy.color, ' ');
		break; case 'p': clientPut(copy.color, copy.cell);

		break; case '~': {
			cellCopy();
			clientPut(input.color, tile.cells[cellY][cellX]);
			clientMove(1, 0);
		}
		break; case '*': {
			clientPut(
				tile.colors[cellY][cellX] ^ ColorBright,
				tile.cells[cellY][cellX]
			);
			clientMove(1, 0);
		}
		break; case '(': {
			clientPut(
				colorInvert(tile.colors[cellY][cellX]),
				tile.cells[cellY][cellX]
			);
			clientMove(1, 0);
		}

		break; case CTRL('A'): {
			clientPut(tile.colors[cellY][cellX], tile.cells[cellY][cellX] + 1);
		}
		break; case CTRL('X'): {
			clientPut(tile.colors[cellY][cellX], tile.cells[cellY][cellX] - 1);
		}

		break; case '?': modeHelp();
		break; case 'm': modeMap();
		break; case 'I': modeDirection();
		break; case 'i': modeInsert(1, 0);
		break; case 'a': modeInsert(1, 0); clientMove(1, 0);
		break; case 'r': modeReplace(); cellCopy();
		break; case 'R': modeDraw();
		break; case '.': modeLine();
	}
}

static void inputHelp(bool keyCode, wchar_t ch) {
	(void)keyCode;
	(void)ch;
	if (tileMeta(&tile).createTime) drawTile(&tile);
	modeNormal();
}

static void inputMap(bool keyCode, wchar_t ch) {
	(void)keyCode;
	(void)ch;
	drawTile(&tile);
	modeNormal();
}

static void inputDirection(bool keyCode, wchar_t ch) {
	if (keyCode) return;
	switch (ch) {
		break; case Esc: modeNormal();
		break; case 'h': modeInsert(-1,  0);
		break; case 'l': modeInsert( 1,  0);
		break; case 'k': modeInsert( 0, -1);
		break; case 'j': modeInsert( 0,  1);
		break; case 'y': modeInsert(-1, -1);
		break; case 'u': modeInsert( 1, -1);
		break; case 'b': modeInsert(-1,  1);
		break; case 'n': modeInsert( 1,  1);
	}
}

static void inputInsert(bool keyCode, wchar_t ch) {
	if (keyCode) {
		if (ch == KEY_BACKSPACE) {
			ch = '\b';
		} else {
			inputNormal(keyCode, ch);
			return;
		}
	}
	switch (ch) {
		break; case Esc: {
			clientMove(-insert.dx, -insert.dy);
			modeNormal();
		}
		break; case '\b': case Del: {
			clientMove(-insert.dx, -insert.dy);
			clientPut(input.color, ' ');
			insert.len--;
		}
		break; case '\n': {
			clientMove(insert.dy, insert.dx);
			clientMove(insert.len * -insert.dx, insert.len * -insert.dy);
			insert.len = 0;
		}
		break; default: {
			uint8_t cell = inputCell(ch);
			if (!cell) break;
			clientPut(input.color, cell);
			clientMove(insert.dx, insert.dy);
			insert.len++;
		}
	}
}

static void inputReplace(bool keyCode, wchar_t ch) {
	if (keyCode) {
		inputNormal(keyCode, ch);
		return;
	}
	if (ch != Esc) {
		uint8_t cell = inputCell(ch);
		if (!cell) return;
		clientPut(tile.colors[cellY][cellX], cell);
	}
	modeNormal();
}

static void inputDraw(bool keyCode, wchar_t ch) {
	if (!keyCode && ch == Esc) {
		modeNormal();
		return;
	}
	if (input.draw) {
		inputNormal(keyCode, ch);
	} else {
		if (keyCode) {
			inputNormal(keyCode, ch);
			return;
		}
		input.draw = inputCell(ch);
	}
	clientPut(input.color, input.draw);
}

static uint8_t lineCell(uint8_t cell, int8_t dx, int8_t dy) {
	if (dx < 0) {
		switch (CP437[cell]) {
			default:   return inputCell(L'→');
			case L'←': return inputCell(L'─'); case L'─': return 0;
			case L'↑': return inputCell(L'┐'); case L'┐': return 0;
			case L'↓': return inputCell(L'┘'); case L'┘': return 0;
			case L'│': return inputCell(L'┤'); case L'┤': return 0;
			case L'└': return inputCell(L'┴'); case L'┴': return 0;
			case L'┌': return inputCell(L'┬'); case L'┬': return 0;
			case L'├': return inputCell(L'┼'); case L'┼': return 0;
		}
	} else if (dx > 0) {
		switch (CP437[cell]) {
			default:   return inputCell(L'←');
			case L'→': return inputCell(L'─'); case L'─': return 0;
			case L'↑': return inputCell(L'┌'); case L'┌': return 0;
			case L'↓': return inputCell(L'└'); case L'└': return 0;
			case L'│': return inputCell(L'├'); case L'├': return 0;
			case L'┘': return inputCell(L'┴'); case L'┴': return 0;
			case L'┐': return inputCell(L'┬'); case L'┬': return 0;
			case L'┤': return inputCell(L'┼'); case L'┼': return 0;
		}
	} else if (dy < 0) {
		switch (CP437[cell]) {
			default:   return inputCell(L'↓');
			case L'↑': return inputCell(L'│'); case L'│': return 0;
			case L'←': return inputCell(L'└'); case L'└': return 0;
			case L'→': return inputCell(L'┘'); case L'┘': return 0;
			case L'─': return inputCell(L'┴'); case L'┴': return 0;
			case L'┌': return inputCell(L'├'); case L'├': return 0;
			case L'┐': return inputCell(L'┤'); case L'┤': return 0;
			case L'┬': return inputCell(L'┼'); case L'┼': return 0;
		}
	} else if (dy > 0) {
		switch (CP437[cell]) {
			default:   return inputCell(L'↑');
			case L'↓': return inputCell(L'│'); case L'│': return 0;
			case L'←': return inputCell(L'┌'); case L'┌': return 0;
			case L'→': return inputCell(L'┐'); case L'┐': return 0;
			case L'─': return inputCell(L'┬'); case L'┬': return 0;
			case L'└': return inputCell(L'├'); case L'├': return 0;
			case L'┘': return inputCell(L'┤'); case L'┤': return 0;
			case L'┴': return inputCell(L'┼'); case L'┼': return 0;
		}
	}
	return 0;
}

static void inputLine(bool keyCode, wchar_t ch) {
	int8_t dx = 0;
	int8_t dy = 0;
	if (keyCode) {
		switch (ch) {
			break; case KEY_LEFT:  dx = -1;
			break; case KEY_RIGHT: dx =  1;
			break; case KEY_UP:    dy = -1;
			break; case KEY_DOWN:  dy =  1;
			break; default: return;
		}
	} else {
		switch (ch) {
			break; case Esc: case '.': modeNormal(); return;
			break; case 'h': dx = -1;
			break; case 'l': dx =  1;
			break; case 'k': dy = -1;
			break; case 'j': dy =  1;
			break; default: return;
		}
	}

	uint8_t leave = lineCell(tile.cells[cellY][cellX], dx, dy);
	uint8_t enter = lineCell(tile.cells[cellY + dy][cellX + dx], -dx, -dy);

	if (leave) clientPut(input.color, leave);

	if ((uint8_t)(cellX + dx) >= CellCols) return;
	if ((uint8_t)(cellY + dy) >= CellRows) return;
	clientMove(dx, dy);

	if (enter) clientPut(input.color, enter);
}

static void readInput(void) {
	wint_t ch;
	bool keyCode = (KEY_CODE_YES == get_wch(&ch));
	switch (input.mode) {
		break; case ModeNormal:    inputNormal(keyCode, ch);
		break; case ModeHelp:      inputHelp(keyCode, ch);
		break; case ModeMap:       inputMap(keyCode, ch);
		break; case ModeDirection: inputDirection(keyCode, ch);
		break; case ModeInsert:    inputInsert(keyCode, ch);
		break; case ModeReplace:   inputReplace(keyCode, ch);
		break; case ModeDraw:      inputDraw(keyCode, ch);
		break; case ModeLine:      inputLine(keyCode, ch);
	}
}

int main(int argc, char *argv[]) {
	int error;
	const char *sockPath = DefaultSockPath;
	int opt;
	while (0 < (opt = getopt(argc, argv, "hs:"))) {
		switch (opt) {
			break; case 'h': {
				fwrite(HelpData, sizeof(HelpData), 1, stdout);
				return EX_OK;
			}
			break; case 's': sockPath = optarg;
			break; default:  return EX_USAGE;
		}
	}

	curse();

#ifdef __OpenBSD__
	error = pledge("stdio tty unix", NULL);
	if (error) err(EX_OSERR, "pledge");
#endif

	modeHelp();
	readInput();

	client = socket(PF_LOCAL, SOCK_STREAM, 0);
	if (client < 0) err(EX_OSERR, "socket");

	struct sockaddr_un addr = { .sun_family = AF_LOCAL };
	snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", sockPath);
	error = connect(client, (struct sockaddr *)&addr, SUN_LEN(&addr));
	if (error) err(EX_NOINPUT, "%s", sockPath);

#ifdef __OpenBSD__
	error = pledge("stdio tty", NULL);
	if (error) err(EX_OSERR, "pledge");
#endif

	struct pollfd fds[2] = {
		{ .fd = STDIN_FILENO, .events = POLLIN },
		{ .fd = client, .events = POLLIN },
	};
	for (;;) {
		int nfds = poll(fds, 2, -1);
		if (nfds < 0 && errno == EINTR) continue;
		if (nfds < 0) err(EX_IOERR, "poll");

		if (fds[0].revents) readInput();
		if (fds[1].revents) readMessage();

		refresh();
	}
}