fn backup_file_path(file_path: &std::path::Path) -> Result<std::path::PathBuf, ask_dracula::Error>
{
	let file_name = file_path.file_name()
		.ok_or(ask_dracula::Error::new_not_a_file(file_path.to_owned()))?;

	let mut i = 0;

	loop
	{
		i += 1;

		let backup_file_name = format!("{}.{}~", file_name.to_string_lossy(), i);
		let backup_file_path = file_path.with_file_name(backup_file_name);

		if !backup_file_path.exists()
		{
			return Ok(backup_file_path);
		}
	}
}

fn find_conjecture<'a, 'input>(project: &'a ask_dracula::Project<'input>) -> Option<&'a ask_dracula::project::Statement<'input>>
{
	for block in &project.blocks
	{
		if let ask_dracula::project::Block::Statement(ref statement) = block
		{
			if statement.kind == ask_dracula::project::StatementKind::Lemma
				|| statement.kind == ask_dracula::project::StatementKind::Conjecture
			{
				return Some(statement)
			}
		}
	}

	None
}

fn find_conjecture_mut<'a, 'input>(project: &'a mut ask_dracula::Project<'input>) -> Option<&'a mut ask_dracula::project::Statement<'input>>
{
	for block in &mut project.blocks
	{
		if let ask_dracula::project::Block::Statement(ref mut statement) = block
		{
			if statement.kind == ask_dracula::project::StatementKind::Lemma
				|| statement.kind == ask_dracula::project::StatementKind::Conjecture
			{
				return Some(statement)
			}
		}
	}

	None
}

enum ProofResult
{
	ProofNotFound,
	Refutation,
	Satisfiable,
}

fn run_vampire<I, S>(input: &str, arguments: Option<I>)
	-> Result<ProofResult, ask_dracula::Error>
	where I: IntoIterator<Item = S>, S: AsRef<std::ffi::OsStr>
{
	let mut vampire = std::process::Command::new("vampire");

	let vampire = match arguments
	{
		Some(arguments) => vampire.args(arguments),
		None => &mut vampire,
	};

	//eprintln!("{}", input);

	let mut vampire = vampire
		.stdin(std::process::Stdio::piped())
		.stdout(std::process::Stdio::piped())
		.stderr(std::process::Stdio::piped())
		.spawn()
		.map_err(|error| ask_dracula::Error::new_run_vampire(error))?;

	{
		use std::io::Write;

		let vampire_stdin = vampire.stdin.as_mut().unwrap();
		vampire_stdin.write_all(input.as_bytes())
			.map_err(|error| ask_dracula::Error::new_run_vampire(error))?;
	}

	let output = vampire.wait_with_output()
		.map_err(|error| ask_dracula::Error::new_run_vampire(error))?;

	let stdout = std::str::from_utf8(&output.stdout)
		.map_err(|error| ask_dracula::Error::new_run_vampire(error))?;

	let stderr = std::str::from_utf8(&output.stderr)
		.map_err(|error| ask_dracula::Error::new_run_vampire(error))?;

	if !output.status.success()
	{
		let proof_not_found_regex = regex::Regex::new(r"% \(\d+\)Proof not found in time").unwrap();

		if proof_not_found_regex.is_match(stdout)
		{
			return Ok(ProofResult::ProofNotFound);
		}

		return Err(ask_dracula::Error::new_run_vampire(
			format!("Vampire returned unsuccessful exit code ({})\n\n======== stdout ========\n{}\n\n======== stderr ========\n{}", output.status, std::str::from_utf8(&output.stdout).unwrap_or("(not valid UTF-8)").trim(), std::str::from_utf8(&output.stderr).unwrap_or("(not valid UTF-8)").trim())));
	}

	let refutation_regex = regex::Regex::new(r"% \(\d+\)Termination reason: Refutation").unwrap();

	if refutation_regex.is_match(stdout)
	{
		return Ok(ProofResult::Refutation);
	}

	Err(ask_dracula::Error::new_interpret_vampire_output(stdout.to_string(), stderr.to_string()))
}

fn main() -> Result<(), Box<dyn std::error::Error>>
{
	let matches = clap::App::new("Ask Dracula: Using Vampire as an interactive theorem prover")
		.arg(clap::Arg::with_name("file").takes_value(true).required(true))
		.arg(clap::Arg::with_name("vampire_arguments").multiple(true))
		.after_help("example: ask_dracula <project file> -- --mode casc --cores 8")
		.get_matches();

	let file = matches.value_of("file").unwrap().to_string();
	let file_path = std::path::Path::new(&file);

	let file_content = std::fs::read_to_string(&file_path)?;
	let (_, mut project) = ask_dracula::parse::project(&file_content)
		.map_err(|_| "couldn’t parse input file")?;

	let conjecture = find_conjecture(&project);

	let vampire_result = match conjecture
	{
		None =>
		{
			eprintln!("no lemma or conjecture found, nothing to do");
			return Ok(());
		},
		Some(ref conjecture) =>
		{
			eprintln!("verifying conjecture: {}", conjecture.formula);

			let tptp_content = format!("{}", ask_dracula::format_tptp::display_project_with_conjecture_tptp(&project, conjecture));

			run_vampire(&tptp_content, matches.values_of("vampire_arguments").map(|value| value))?
		},
	};

	let conjecture = find_conjecture_mut(&mut project).unwrap();

	match vampire_result
	{
		ProofResult::ProofNotFound =>
		{
			println!("proof not found");
			Ok(())
		},
		ProofResult::Refutation =>
		{
			println!("conjecture proven");

			conjecture.kind = ask_dracula::project::StatementKind::Axiom;
			let replace_statement_kind_regex = regex::Regex::new(r"(conjecture|lemma)").unwrap();
			let new_text = replace_statement_kind_regex.replace(conjecture.original_text, "axiom");
			conjecture.original_text = &new_text;

			let backup_file_path = backup_file_path(file_path)?;

			// Make backup of old file
			std::fs::rename(file_path, backup_file_path)
				.map_err(|error| ask_dracula::Error::new_write_file(file_path.to_owned(), error))?;

			// Write updated version of the file
			let file_content = format!("{}", project);
			std::fs::write(file_path, &file_content)
				.map_err(|error| ask_dracula::Error::new_write_file(file_path.to_owned(), error))?;

			Ok(())
		},
		ProofResult::Satisfiable =>
		{
			println!("conjecture disproven");
			Ok(())
		},
	}
}