use std::io::{
	Write,
	stdin,
	stdout,
};

/// As a dare to myself, I won't use any error-handling crates.

#[derive (Debug)]
enum GameError {
	IoError,
}

impl From <std::io::Error> for GameError {
	fn from (_: std::io::Error) -> Self {
		Self::IoError
	}
}

type Result <T> = std::result::Result <T, GameError>;

/// Prints a string, naively wrapping at 80-character boundaries
/// This means a period might be wrapped separate from the sentence it ends
/// , and frankly I think that's part of the charm.

fn print (mut s: &str) {
	const COLS: usize = 80;
	
	while s.len () > COLS {
		println! ("{}", &s [0..80]);
		s = &s [80..];
	}
	
	println! ("{}", s);
}

fn print_help () {
	print ("All commands are ASCII and case-insensitive.");
	print ("Commands should start with a verb like LOOK.");
	print ("e.g. `look table`");
	print ("Single-word verbs are better, e.g. prefer `hint` over `give me a hint`");
	print ("When in doubt, try generic verbs like `look` or `use` over specific verbs like `actuate`, `type`, or `consolidate`.");
}

fn print_undetected_item () {
	print ("That ITEM does not exist in this ROOM, or you have not detected it.");
}

fn read_input () -> Result <String> {
	{
		let mut stdout = stdout ();
		stdout.write_all (b"> ")?;
		stdout.flush ()?;
	}
	
	let mut buffer = String::new ();
	stdin ().read_line (&mut buffer)?;
	
	// I don't know why I need the type annotation here, but I do.
	let x: &[_] = &['\r', '\n'];
	let buffer = buffer.trim_end_matches (x).to_string ();
	
	Ok (buffer)
}

#[derive (Debug, PartialEq)]
enum PlayerAction {
	Quit,
	Help,
	Hint,
	Nonsense,
	Wait,
	Look (ItemName),
	LookAround,
}

#[derive (Clone, Copy, Debug, PartialEq)]
enum ItemName {
	Nonsense,
	
	Door,
	EmergencyExit,
	Keypad,
	Note,
	Table,
}

fn item_name_display (x: ItemName) -> &'static str {
	match x {
		Nonsense => "NONSENSE",
		
		Door => "DOOR",
		EmergencyExit => "EMERGENCY EXIT",
		Keypad => "KEYPAD",
		Note => "NOTE",
		Table => "TABLE",
	}
}

fn parse_input (s: &str) -> PlayerAction {
	let s = s.to_lowercase ();
	
	if s == "quit" || s == "quit game" {
		return PlayerAction::Quit;
	}
	
	if s == "look" || s == "look around" {
		return PlayerAction::LookAround;
	}
	
	if let Some (rest) = s.strip_prefix ("look at the ") {
		return PlayerAction::Look (parse_item_name (rest));
	}
	
	if let Some (rest) = s.strip_prefix ("look at ") {
		return PlayerAction::Look (parse_item_name (rest));
	}
	
	if let Some (rest) = s.strip_prefix ("look ") {
		return PlayerAction::Look (parse_item_name (rest));
	}
	
	if let Some (rest) = s.strip_prefix ("examine ") {
		return PlayerAction::Look (parse_item_name (rest));
	}
	
	if s == "do nothing" {
		return PlayerAction::Wait;
	}
	if s == "wait" {
		return PlayerAction::Wait;
	}
	
	if s == "help" {
		return PlayerAction::Help;
	}
	if s == "hint" {
		return PlayerAction::Hint;
	}
	
	PlayerAction::Nonsense
}

fn parse_item_name (s: &str) -> ItemName {
	if s == "door" {
		return ItemName::Door;
	}
	
	if s == "emergency exit" {
		return ItemName::EmergencyExit;
	}
	
	if s == "keypad" {
		return ItemName::Keypad;
	}
	
	if s == "note" {
		return ItemName::Note;
	}
	
	if s == "table" {
		return ItemName::Table;
	}
	
	ItemName::Nonsense
}

#[derive (Default)]
struct StateRoom1 {
	detected_keypad: bool,
	detected_note: bool,
}

#[derive (Default)]
struct State {
	quitting: bool,
	room_1: StateRoom1,
}

fn room_1 (state: &mut State) -> Result <()> {
	let input = read_input ()?;
	let action = parse_input (&input);
	
	match action {
		PlayerAction::Quit => {
			print ("Bye.");
			state.quitting = true;
		}
		PlayerAction::Help => {
			print_help ();
		},
		PlayerAction::Hint => {
			print ("Hint for this room: Try using the `help` command.");
		},
		PlayerAction::Nonsense => {
			print ("I couldn't understand that. Try `help` or `hint`.");
			print ("`hint` may contain spoilers. `help` will not.");
		},
		PlayerAction::Wait => {
			print ("You wait around a bit. You can hear humming from the electrical lights, and the distant rumble of the building's HVAC system. The room smells faintly of fresh paint. Nothing has changed.");
		},
		PlayerAction::LookAround => {
			print ("You are in a small room. In one corner is a TABLE. Obvious exits are a locked DOOR, and an EMERGENCY EXIT.");
		}
		PlayerAction::Look (item_name) => {
			match item_name {
				ItemName::Nonsense => {
					print_undetected_item ();
				},
				ItemName::Door => {
					print ("You examine the DOOR. It is firmly locked, and you don't have any lock-picking tools. On the DOOR is an electronic KEYPAD.");
					state.room_1.detected_keypad = true;
				},
				ItemName::EmergencyExit => {
					print ("The EMERGENCY EXIT reads, \"Emergency exit. Push bar to open. Alarm will sound. Door will unlock in 15 seconds.\". The EMERGENCY EXIT is period-accurate for an American Wal-Mart c. 2020 C.E.");
				},
				ItemName::Keypad => {
					if state.room_1.detected_keypad {
						print ("The DOOR is locked by an electronic KEYPAD. A soft amber power light indicates that the KEYPAD is likely functional. The KEYPAD buttons are the digits 0-9, Enter, and Clear. Experience tells you that the key code is likely 4 or 5 digits long.");
					}
					else {
						print_undetected_item ();
					}
				},
				ItemName::Note => {
					if state.room_1.detected_note {
						for x in [
							"You pick up the NOTE and read it.",
							"",
							"Welcome to SEROTONIN DEPOSITORY.",
							"As you play, keep in mind:",
							"- LOOKing at ITEMS is not always safe",
							"- TAKEing an item may be bad long-term",
							"- WAITing counts as an action",
							"- LOOKing AROUND is always safe",
							"- Other NOTEs may contain non-truths",
							"The code for this first KEYPAD is 1234.",
							"",
							"    -- Phayle Sayf",
							"",
							"You notice that the NOTE is _not_ period-accurate.",
						].into_iter () {
							print (x);
						}
					}
					else {
						print_undetected_item ();
					}
				},
				ItemName::Table => {
					print ("You look at the TABLE. Your instincts tell you that it is period-accurate. Upon the TABLE sits a NOTE.");
					state.room_1.detected_note = true;
				},
			}
		},
	}
	
	Ok (())
}

fn main () -> Result <()> {
	print ("Welcome to SEROTONIN DEPOSITORY, the only adventure game ever made.");
	print ("");
	print ("You have been consensually kidnapped by a diabolical ADVENTURE GAME ENTHUSIAST and encouraged to solve PUZZLES for their sick PLEASURE. The only winning move is to solve all the PUZZLES.");
	print ("");
	print ("Press ENTER if you dare to begin.");
	
	let input = read_input ()?;
	
	if ! input.is_empty () {
		print ("That was more than just ENTER but OKAY, overachiever.");
	}
	
	print ("");
	
	let mut state = State::default ();
	
	print ("You are in a small room. In one corner is a TABLE.");
	
	while ! state.quitting {
		room_1 (&mut state)?;
	}
	
	Ok (())
}

#[cfg (test)]
mod test {
	#[test]
	fn parse_input () {
		use super::{
			ItemName,
			PlayerAction::*,
		};
		
		for (input, expected) in [
			 ("", Nonsense),
			 ("look at the table", Look (ItemName::Table)),
			 ("look at table", Look (ItemName::Table)),
			 ("look table", Look (ItemName::Table)),
			 ("LOOK TABLE", Look (ItemName::Table)),
			 ("wait", Wait),
			 ("help", Help),
			 ("hint", Hint),
		].into_iter () {
			let actual = super::parse_input (input);
			assert_eq! (actual, expected);
		}
	}
}