use super::Cmd;
use clap::{Arg, ArgAction, ArgGroup, ArgMatches, Command, ValueHint};
use std::{
    error::Error,
    fmt,
    fs::{self, File, Metadata},
    io,
    path::PathBuf,
    str::FromStr,
};

#[derive(Debug, Default)]
pub struct Rm;

impl Cmd for Rm {
    fn cli(&self) -> clap::Command {
        Command::new("rm")
            .about("remove files or directories")
            .author("Nathan Fisher")
            .version(env!("CARGO_PKG_VERSION"))
            .args([
                Arg::new("fullnag")
                    .short('i')
                    .help("prompt before every removal")
                    .action(ArgAction::SetTrue),
                Arg::new("softnag")
                    .short('I')
                    .help(
                        "prompt once before removing more than three files, or \
                        when removing recursively;\nless  intrusive than -i, while \
                        still giving protection against most mistakes",
                    )
                    .next_line_help(true)
                    .action(ArgAction::SetTrue),
                Arg::new("interactive")
                    .long("interactive")
                    .help("when to prompt")
                    .value_parser(["never", "once", "always"])
                    .value_name("WHEN")
                    .num_args(0..=1)
                    .require_equals(true)
                    .default_missing_value("always"),
                Arg::new("force")
                    .short('f')
                    .long("force")
                    .help("ignore nonexistent files and arguments, never prompt")
                    .action(ArgAction::SetTrue),
                Arg::new("recursive")
                    .short('r')
                    .long("recursive")
                    .visible_short_alias('R')
                    .help("remove directories and their contents recursively")
                    .action(ArgAction::SetTrue),
                Arg::new("verbose")
                    .short('v')
                    .long("verbose")
                    .help("explain what is being done")
                    .action(ArgAction::SetTrue),
                Arg::new("file")
                    .value_name("FILE")
                    .value_hint(ValueHint::AnyPath)
                    .num_args(1..)
                    .required(true),
            ])
            .group(
                ArgGroup::new("nag")
                    .args(["fullnag", "softnag", "interactive", "force"])
                    .required(false)
                    .multiple(false),
            )
    }

    fn run(&self, matches: Option<&clap::ArgMatches>) -> Result<(), Box<dyn std::error::Error>> {
        let Some(matches) = matches else {
            return Err(Box::new(io::Error::new(io::ErrorKind::Other, "no input")));
        };
        let mut actions = AllActions::from(matches);
        let proceed = match actions.prompt {
            When::Always => true,
            When::Once => {
                if actions.items.len() > 2 {
                    let res = actions.prompt();
                    if res {
                        actions.prompt = When::Never;
                    }
                    res
                } else {
                    true
                }
            }
            _ => true,
        };
        if proceed {
            for act in actions.items {
                if let Err(e) = act.apply() {
                    if !act.force {
                        return Err(e.into());
                    }
                }
            }
        }
        Ok(())
    }

    fn path(&self) -> Option<crate::Path> {
        Some(crate::Path::Bin)
    }
}

#[derive(Clone, Copy, PartialEq)]
enum When {
    Never,
    Once,
    Always,
}

impl Default for When {
    fn default() -> Self {
        Self::Once
    }
}

#[derive(Debug)]
pub struct ParseWhenError;

impl fmt::Display for ParseWhenError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{self:?}")
    }
}

impl FromStr for When {
    type Err = ParseWhenError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "never" => Ok(Self::Never),
            "once" => Ok(Self::Once),
            "always" => Ok(Self::Always),
            _ => Err(ParseWhenError),
        }
    }
}

enum Filetype {
    File,
    Dir,
    Symlink,
}

impl From<Metadata> for Filetype {
    fn from(meta: Metadata) -> Self {
        let ft = meta.file_type();
        if ft.is_dir() {
            Self::Dir
        } else if ft.is_symlink() {
            Self::Symlink
        } else {
            Self::File
        }
    }
}

impl fmt::Display for Filetype {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "{}",
            match self {
                Self::File => "file",
                Self::Symlink => "symlink",
                Self::Dir => "directory",
            }
        )
    }
}

struct Action {
    path: String,
    prompt: When,
    force: bool,
    recursive: bool,
    verbose: bool,
}

impl Action {
    fn apply(&self) -> Result<(), Box<dyn Error>> {
        let ft = if self.prompt == When::Always {
            match self.prompt() {
                Ok(Some(ft)) => ft,
                Ok(None) => return Ok(()),
                Err(e) => {
                    if !self.force {
                        return Err(e.into());
                    } else {
                        return Ok(());
                    }
                }
            }
        } else {
            match File::open(&self.path)
                .and_then(|fd| fd.metadata())
                .and_then(|meta| Ok(Filetype::from(meta)))
            {
                Ok(ft) => ft,
                Err(e) => {
                    if !self.force {
                        return Err(e.into());
                    } else {
                        return Ok(());
                    }
                }
            }
        };
        match ft {
            Filetype::File | Filetype::Symlink => {
                fs::remove_file(&self.path)?;
                if self.verbose {
                    println!("removed '{}'", &self.path);
                }
            }
            Filetype::Dir => {
                if self.recursive {
                    match fs::read_dir(&self.path) {
                        Ok(items) => {
                            for entry in items {
                                let act = Action {
                                    path: entry?.path().to_string_lossy().to_string(),
                                    prompt: self.prompt,
                                    force: self.force,
                                    recursive: self.recursive,
                                    verbose: self.verbose,
                                };
                                act.apply()?;
                            }
                        }
                        Err(e) => {
                            if !self.force {
                                return Err(e.into());
                            }
                        }
                    }
                    fs::remove_dir(&self.path)?;
                    if self.verbose {
                        println!("removed directory '{}'", &self.path);
                    }
                } else if !self.force {
                    let msg = format!("cannot remove '{}': is a directory", &self.path);
                    return Err(Box::new(io::Error::new(io::ErrorKind::Other, msg)));
                }
            }
        }
        Ok(())
    }

    fn prompt(&self) -> Result<Option<Filetype>, Box<dyn Error>> {
        let path = PathBuf::from(&self.path);
        let ft: Filetype = if path.is_dir() {
            if self.recursive {
                return Ok(Some(Filetype::Dir));
            } else {
                return Ok(None);
            }
        } else {
            File::open(path)
                .and_then(|fd| fd.metadata())
                .and_then(|meta| Ok(Filetype::from(meta)))?
        };
        print!("rm: remove {ft} '{}'? ", &self.path);
        let mut reply = String::new();
        let stdin = io::stdin();
        let _read = stdin.read_line(&mut reply);
        match reply.as_str() {
            "y" | "Y" | "yes" | "Yes" => Ok(Some(ft)),
            _ => Ok(None),
        }
    }
}

struct AllActions {
    items: Vec<Action>,
    prompt: When,
}

impl From<&ArgMatches> for AllActions {
    fn from(matches: &ArgMatches) -> Self {
        let force = matches.get_flag("force");
        let prompt = if force {
            When::Never
        } else if matches.get_flag("fullnag") {
            When::Always
        } else if matches.get_flag("softnag") {
            When::Once
        } else {
            match matches.get_one::<String>("interactive") {
                Some(w) => w.parse().unwrap_or_default(),
                None => When::default(),
            }
        };
        let mut items: Vec<Action> = vec![];
        if let Some(files) = matches.get_many::<String>("file") {
            for f in files {
                items.push(Action {
                    path: f.to_owned(),
                    prompt,
                    force,
                    recursive: matches.get_flag("recursive"),
                    verbose: matches.get_flag("verbose"),
                });
            }
        }
        AllActions { items, prompt }
    }
}

impl AllActions {
    fn prompt(&self) -> bool {
        let len = self.items.len();
        if len > 3 {
            print!("rm: remove {len} arguments? ");
        }
        let mut reply = String::new();
        let stdin = io::stdin();
        let _read = stdin.read_line(&mut reply);
        match reply.as_str() {
            "y" | "Y" | "yes" | "Yes" => true,
            _ => false,
        }
    }
}