use super::*;
use std::{
    fmt,
    path::{
	Path,PathBuf,
    },
};
use lazy_static::lazy_static;

/// Get the program name
pub fn program() -> &'static str
{
    lazy_static!{
	static ref NAME: &'static str = Box::leak(std::env::args().next().unwrap().into_boxed_str());
    }

    &NAME
}

pub fn usage() -> !
{
    println!("rmdupe version {}", env!("CARGO_PKG_VERSION"));
    println!(" by {}", env!("CARGO_PKG_AUTHORS"));
    println!(" (licensed with GNU GPL v3)\n");
    println!("Usage: {} [OPTIONS] [--] <dirs...>", program());
    println!("Usage: {} --rebase [<files>]", program());
    println!("Usage: {} --help", program());
    println!("OPTIONS:");
    println!("  --load -l:\t\tLoad the hashes from `load-file` if possible.");
    println!("  --save -s:\t\tSave the hashes to `save-file` if possible.");
    println!("  --load-file <file>\tSpecify file for `--load`");
    println!("  --save-file <file>\tSpecify file for `--save`");
    println!("  --load-save <file>\tSpecify file for `--save` and `--load`");
    println!("  --delete -d\t\tDelete dupes instead of printing");
    println!("  --verbose -v\t\tPrint verbose info");
    println!("  --debug -V\t\tPrint very verbose info");
    println!("  --error-mode <mode>\tSpecify error handling mode, one of: [IGNORE|WARN|CANCEL|TERMINATE]. Default is `WARN`");
    println!("  --quiet -q\t\tAlias for `--error-mode IGNORE`");
    println!("  --warn -i\t\tAlias for `--error-mode WARN`");
    println!("  --cancel -w\t\tAlias for `--error-mode CANCEL`");
    println!("  --error -W\t\tAlias for `--error-mode TERMINATE`");
    println!("  --recurse <max>|inf\tRecursive mode, give max depth or infinite.");
    #[cfg(feature="threads")]
    println!("  --threads <max>|inf\tMax number of threads to run at once.");
    #[cfg(feature="threads")]
    println!("    -U\t\tUlimited max threads.");
    #[cfg(feature="threads")]
    println!("  --sync -S\t\tRun only one file at a time.");
    println!("  --\t\t\tStop reading args");
    println!("Other:");
    println!("  --help -h:\t\tPrint this message");
    println!("  --rebase:\t\tRebuild hash stores created by `--save`. If no files are provided, use default.");
    #[cfg(feature="threads")]
    println!("Compiled with threading support");
    std::process::exit(1)
}

enum Ensure
{
    None,
    Dir,
    File,
}

impl Default for Ensure
{
    fn default() -> Self {
	Self::None
    }
}

fn validate_path<P>(path: P, ensure: Ensure, must_exist: bool) -> Result<P, Error>
where P: AsRef<Path>
{
    if !must_exist || path.as_ref().exists() {
	if !must_exist && !path.as_ref().exists() {return Ok(path);}
	match ensure {
	    Ensure::File => {
		if !path.as_ref().is_file() {
		    Err(Error::ExpectedFile(path.as_ref().to_owned()))
		} else {
		    Ok(path)
		}
	    },
	    Ensure::Dir => {
		if !path.as_ref().is_dir() {
		    Err(Error::ExpectedDirectory(path.as_ref().to_owned()))
		} else {
		    Ok(path)
		}
	    },
	    _ => Ok(path),
	}
    } else {
	Err(Error::FileNotFound(path.as_ref().to_owned()))
    }
}

/// Try to parse `std::env::args()`
#[inline]
pub fn parse_args() -> Result<Output, Error>
{
    parse(std::env::args().skip(1))
}

#[derive(Debug)]
pub enum Output
{
    Normal(config::Config),
    Help,
    Rebase(config::Rebase),
}

/// Arg parse for rebase
fn parse_rebase<I>(args: I) -> Result<config::Rebase, Error>
where I: IntoIterator<Item=String>
{
    let mut files = Vec::new();

    for file in args.into_iter().map(|path| validate_path(path, Ensure::File, true))
    {
	files.push(file?);
    }

    if files.len() < 1 {
	files.push(validate_path(config::DEFAULT_HASHNAME.to_string(), Ensure::File, false)?.to_owned());
    }

    Ok(config::Rebase{
	save: files.clone(), //TODO: Seperate save+loads
	load: files,

	#[cfg(feature="threads")]
	max_threads: config::MAX_THREADS,
    })
}

/// Try to parse args
pub fn parse<I>(args: I) -> Result<Output, Error>
where I: IntoIterator<Item=String>
{
    let mut args = args.into_iter();
    let mut reading = true;
    
    let mut paths = Vec::new();
    let mut load = Vec::new();
    let mut save = Vec::new();
    let mut delete = false;
    let mut mode_er = error::Mode::Cancel;
    let mut mode_rec = config::RecursionMode::None;
    let mut mode_log = log::Mode::Warn;

    #[cfg(feature="threads")]
    let mut threads = config::MAX_THREADS;
    
    macro_rules! push {
	($arg:expr) => {
	    {
		let arg = $arg;
		paths.push(validate_path(&arg, Ensure::None, true)?.to_owned())
	    }
	};
    }
    let mut one = String::new();
    macro_rules! take_one {
	() => {
	    {
		match args.next() {
		    Some(a) => {one = a; true},
		    _ => false,
		}
	    }
	}
    }
    
    while let Some(arg) = args.next()
    {
	if reading && arg.chars().next().unwrap_or('\0') == '-' {
	    match &arg[..] {
		"--help" => return Ok(Output::Help),
		"--rebase" => return Ok(Output::Rebase(parse_rebase(args)?)),
		
		"--" => reading = false,

		#[cfg(feature="threads")]
		"--threads" if take_one!() => {
		    if one.to_lowercase().trim() == "inf" {
			threads = None;
		    } else {
			threads = Some(one.as_str().parse::<std::num::NonZeroUsize>().or_else(|e| Err(Error::BadNumber(e)))?);
		    }
		},
		#[cfg(feature="threads")]
		"--sync" => threads = Some(unsafe{std::num::NonZeroUsize::new_unchecked(1)}),
		"--load"  => {
		    load.push(validate_path(config::DEFAULT_HASHNAME.to_string(), Ensure::File, false)?.to_owned());
		},
		"--save"  => {
		    save.push(validate_path(config::DEFAULT_HASHNAME.to_string(), Ensure::File, false)?.to_owned());
		},
		"--save-file" if take_one!() => {
		    save.push(validate_path(&one, Ensure::File, false)?.to_owned());
		},
		"--load-file" if take_one!() => {
		    load.push(validate_path(&one, Ensure::Dir, false)?.to_owned());
		},
		"--load-save" if take_one!() => {
		    load.push(validate_path(&one, Ensure::Dir, false)?.to_owned());
		    save.push(validate_path(&one, Ensure::Dir, false)?.to_owned());
		},
		
		"--verbose" => mode_log = log::Mode::Verbose,
		"--debug" => mode_log = log::Mode::Debug,
		"--delete" => delete = true,
		
		"--error" => mode_er = error::Mode::Terminate,
		"--cancel" => mode_er = error::Mode::Cancel,
		"--warn" => mode_er = error::Mode::Warn,
		"--quiet" => mode_er = error::Mode::Ignore,
		"--error-mode" if take_one!() => mode_er = match one.to_lowercase().trim() {
		    "terminate" => error::Mode::Terminate,
		    "cancel" => error::Mode::Cancel,
		    "warn" => error::Mode::Warn,
		    "ignore" => error::Mode::Ignore,
		    _ => return Err(Error::UnknownErrorMode(one)),
		},
		"--recurse" if take_one!() => {
		    if one.to_lowercase().trim() == "inf" {
			mode_rec = config::RecursionMode::All;
		    } else if let Ok(sz) = one.parse::<usize>() {
			mode_rec = if sz == 0 {config::RecursionMode::None} else {config::RecursionMode::N(sz)};
		    } else {
			return Err(Error::Parse(one, "number"));
		    }
		},
		_ if arg.len() > 1 => {
		    // Parse small ones
		    for argchar in arg.chars().skip(1) {
			match argchar {
			    'l' => load.push(validate_path(config::DEFAULT_HASHNAME.to_owned(), Ensure::File, false)?.to_owned()),
			    's' => save.push(validate_path(config::DEFAULT_HASHNAME.to_owned(), Ensure::File, false)?.to_owned()),

			    'd' => delete = true,
			    'v' => mode_log = log::Mode::Verbose,
			    'V' => mode_log = log::Mode::Debug,
			    
			    'W' => mode_er = error::Mode::Terminate,
			    'w' => mode_er = error::Mode::Cancel,
			    'i' => mode_er = error::Mode::Warn,
			    'q' => mode_er = error::Mode::Ignore,

			    'h' => return Ok(Output::Help),
			    
			    #[cfg(feature="threads")]
			    'U' => threads = None,
			    #[cfg(feature="threads")]
			    'S' => threads = Some(unsafe{std::num::NonZeroUsize::new_unchecked(1)}),
			    
			    'r' => mode_rec = config::RecursionMode::All,
			    _ => return Err(Error::UnknownArgChar(argchar)),
			}
		    }
		},
		_ => push!(arg),
	    };
	} else {
	    push!(arg);
	}
    }

    // Remove dupes & keeps ordering
    load.dedup_full();
    save.dedup_full();
    paths.dedup_full();

    if paths.len() < 1 {
	return Err(Error::NoInput);
    }
    
    Ok(Output::Normal(config::Config{
	paths: paths,
	mode: config::Mode{
	    error_mode: mode_er,
	    recursion_mode: mode_rec,
	    operation_mode: if delete { config::OperationMode::Delete } else { config::OperationMode::Print },
	    logging_mode: mode_log,
	},
	save,
	load,
	#[cfg(feature="threads")]
	max_threads: threads,
    }))
}

#[derive(Debug)]
pub enum Error
{
    NoInput,
    Parse(String, &'static str),
    UnknownArg(String),
    UnknownArgChar(char),
    FileNotFound(PathBuf),
    ExpectedFile(PathBuf),
    ExpectedDirectory(PathBuf),
    UnknownErrorMode(String),
    BadNumber(std::num::ParseIntError),
    Unknown,
}

impl std::error::Error for Error{}
impl fmt::Display for Error
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
    {
	write!(f, "failed to parse args: ")?;
	match self {
	    Error::BadNumber(num) => write!(f, "{}", num),
	    Error::NoInput => write!(f, "need at least one input"),
	    Error::Parse(value, typ) => write!(f, "expected a {}, got `{}'", typ, value),
	    Error::UnknownArg(arg) => write!(f, "i don't know how to `{}'", arg),
	    Error::UnknownArgChar(arg) => write!(f, "i don't know how to `-{}'", arg),
	    Error::UnknownErrorMode(error) => write!(f, "unknown error mode `{}'", error),
	    Error::ExpectedDirectory(path) => write!(f, "expected directory, got file: {:?}", path),
	    Error::ExpectedFile(path) => write!(f, "expected file, got directory: {:?}", path),
	    Error::FileNotFound(path) => write!(f, "file not found: {:?}", path),
	    _ => write!(f, "unknown error"),
	}
    }
}