//! Rust-Wrapper for youtube-dl
//!
//! # Example
//!
//! ```no_run
//! use ytd_rs::{YoutubeDL, Arg};
//! use std::path::PathBuf;
//! use std::error::Error;
//! fn main() -> Result<(), Box<dyn Error>> {
//!     // youtube-dl arguments quietly run process and to format the output
//!     // one doesn't take any input and is an option, the other takes the desired output format as input
//!     let args = vec![Arg::new("--quiet"), Arg::new_with_arg("--output", "%(title).90s.%(ext)s")];
//!     let link = "https://www.youtube.com/watch?v=uTO0KnDsVH0";
//!     let path = PathBuf::from("./path/to/download/directory");
//!     let ytd = YoutubeDL::new(&path, args, link)?;
//!
//!     // start download
//!     let download = ytd.download()?;
//!
//!     // check what the result is and print out the path to the download or the error
//!     println!("Your download: {}", download.output_dir().to_string_lossy());
//!     Ok(())
//! }
//! ```

use error::YoutubeDLError;
use std::{
    fmt,
    process::{Output, Stdio},
};
use std::{
    fmt::{Display, Formatter},
    fs::{canonicalize, create_dir_all},
    path::PathBuf,
};
use std::{path::Path, process::Command};

pub mod error;
type Result<T> = std::result::Result<T, YoutubeDLError>;

const YOUTUBE_DL_COMMAND: &str = if cfg!(feature = "youtube-dlc") {
    "youtube-dlc"
} else if cfg!(feature = "yt-dlp") {
    "yt-dlp"
} else {
    "youtube-dl"
};

/// A structure that represents an argument of a youtube-dl command.
///
/// There are two different kinds of Arg:
/// - Option with no other input
/// - Argument with input
///
/// # Example
///
/// ```
/// use ytd_rs::Arg;
/// // youtube-dl option to embed metadata into the file
/// // doesn't take any input
/// let simple_arg = Arg::new("--add-metadata");
///
/// // youtube-dl cookies argument that takes a path to
/// // cookie file
/// let input_arg = Arg::new_with_arg("--cookie", "/path/to/cookie");
/// ```
#[derive(Clone, Debug)]
pub struct Arg {
    arg: String,
    input: Option<String>,
}

impl Arg {
    pub fn new(argument: &str) -> Arg {
        Arg {
            arg: argument.to_string(),
            input: None,
        }
    }

    pub fn new_with_arg(argument: &str, input: &str) -> Arg {
        Arg {
            arg: argument.to_string(),
            input: Option::from(input.to_string()),
        }
    }
}

impl Display for Arg {
    fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
        match &self.input {
            Some(input) => write!(fmt, "{} {}", self.arg, input),
            None => write!(fmt, "{}", self.arg),
        }
    }
}

/// Structure that represents a youtube-dl task.
///
/// Every task needs a download location, a list of ['Arg'] that can be empty
/// and a ['link'] to the desired source.
#[derive(Clone, Debug)]
pub struct YoutubeDL {
    path: PathBuf,
    links: Vec<String>,
    args: Vec<Arg>,
}

///
/// This is the result of a [`YoutubeDL`].
///
/// It contains the information about the exit status, the output and the directory it was executed
/// in.
///
#[derive(Debug, Clone)]
pub struct YoutubeDLResult {
    path: PathBuf,
    output: String,
}

impl YoutubeDLResult {
    /// creates a new YoutubeDLResult
    fn new(path: &PathBuf) -> YoutubeDLResult {
        YoutubeDLResult {
            path: path.clone(),
            output: String::new(),
        }
    }

    /// get the output of the youtube-dl process
    pub fn output(&self) -> &str {
        &self.output
    }

    /// get the directory where youtube-dl was executed
    pub fn output_dir(&self) -> &PathBuf {
        &self.path
    }
}

impl YoutubeDL {
    /// Creates a new YoutubeDL job to be executed.
    /// It takes a path where youtube-dl should be executed, a vec! of [`Arg`] that can be empty
    /// and finally a link that can be `""` if no video should be downloaded
    ///
    /// The path gets canonicalized and the directory gets created by the constructor
    pub fn new_multiple_links(
        dl_path: &PathBuf,
        args: Vec<Arg>,
        links: Vec<String>,
    ) -> Result<YoutubeDL> {
        // create path
        let path = Path::new(dl_path);

        // check if it already exists
        if !path.exists() {
            // if not create
            create_dir_all(&path)?;
        }

        // return error if no directory
        if !path.is_dir() {
            return Err(YoutubeDLError::IOError(std::io::Error::new(
                std::io::ErrorKind::Other,
                "path is not a directory",
            )));
        }

        // absolute path
        let path = canonicalize(dl_path)?;
        Ok(YoutubeDL { path, links, args })
    }

    pub fn new(dl_path: &PathBuf, args: Vec<Arg>, link: &str) -> Result<YoutubeDL> {
        YoutubeDL::new_multiple_links(dl_path, args, vec![link.to_string()])
    }

    /// Starts the download and returns when finished the result as [`YoutubeDLResult`].
    pub fn download(&self) -> Result<YoutubeDLResult> {
        let output = self.spawn_youtube_dl()?;
        let mut result = YoutubeDLResult::new(&self.path);

        if !output.status.success() {
            return Err(YoutubeDLError::Failure(String::from_utf8(output.stderr)?));
        }
        result.output = String::from_utf8(output.stdout)?;

        Ok(result)
    }

    fn spawn_youtube_dl(&self) -> Result<Output> {
        let mut cmd = Command::new(YOUTUBE_DL_COMMAND);
        cmd.current_dir(&self.path)
            .env("LC_ALL", "en_US.UTF-8")
            .stdout(Stdio::piped())
            .stderr(Stdio::piped());

        for arg in self.args.iter() {
            match &arg.input {
                Some(input) => cmd.arg(&arg.arg).arg(input),
                None => cmd.arg(&arg.arg),
            };
        }

        for link in self.links.iter() {
            cmd.arg(&link);
        }

        let pr = cmd.spawn()?;
        Ok(pr.wait_with_output()?)
    }
}

#[cfg(test)]
mod tests {
    use crate::{Arg, YoutubeDL};
    use regex::Regex;
    use std::{env, error::Error};

    #[test]
    fn version() -> Result<(), Box<dyn Error>> {
        let current_dir = env::current_dir()?;
        let ytd = YoutubeDL::new(
            &current_dir,
            // get youtube-dl version
            vec![Arg::new("--version")],
            // we don't need a link to print version
            "",
        )?;

        let regex = Regex::new(r"\d{4}\.\d{2}\.\d{2}")?;
        let output = ytd.download()?;

        // check output
        // fails if youtube-dl is not installed
        assert!(regex.is_match(output.output()));
        Ok(())
    }
}