use anyhow::{Context, Result};
use clap::{Parser, Subcommand};
use std::{path::Path, process::exit};

mod app_state;
mod embedded;
mod exercise;
mod init;
mod list;
mod progress_bar;
mod run;
mod watch;

use self::{
    app_state::AppState,
    exercise::InfoFile,
    init::init,
    list::list,
    run::run,
    watch::{watch, WatchExit},
};

/// Rustlings is a collection of small exercises to get you used to writing and reading Rust code
#[derive(Parser)]
#[command(version)]
struct Args {
    #[command(subcommand)]
    command: Option<Subcommands>,
}

#[derive(Subcommand)]
enum Subcommands {
    /// Initialize Rustlings
    Init,
    /// Run a single exercise. Runs the next pending exercise if the exercise name is not specified.
    Run {
        /// The name of the exercise
        name: Option<String>,
    },
    /// Reset a single exercise
    Reset {
        /// The name of the exercise
        name: String,
    },
    /// Return a hint for the given exercise
    Hint {
        /// The name of the exercise
        name: String,
    },
}

fn main() -> Result<()> {
    let args = Args::parse();

    which::which("cargo").context(CARGO_NOT_FOUND_ERR)?;

    let mut info_file = InfoFile::parse()?;
    info_file.exercises.shrink_to_fit();
    let exercises = info_file.exercises;

    if matches!(args.command, Some(Subcommands::Init)) {
        init(&exercises).context("Initialization failed")?;

        println!("{POST_INIT_MSG}");
        return Ok(());
    } else if !Path::new("exercises").is_dir() {
        println!("{PRE_INIT_MSG}");
        exit(1);
    }

    let mut app_state = AppState::new(exercises);

    match args.command {
        None => loop {
            match watch(&mut app_state)? {
                WatchExit::Shutdown => break,
                // It is much easier to exit the watch mode, launch the list mode and then restart
                // the watch mode instead of trying to pause the watch threads and correct the
                // watch state.
                WatchExit::List => list(&mut app_state)?,
            }
        },
        // `Init` is handled above.
        Some(Subcommands::Init) => (),
        Some(Subcommands::Run { name }) => {
            if let Some(name) = name {
                app_state.set_current_exercise_by_name(&name)?;
            }
            run(&mut app_state)?;
        }
        Some(Subcommands::Reset { name }) => {
            app_state.set_current_exercise_by_name(&name)?;
            app_state.set_pending(app_state.current_exercise_ind())?;
            let exercise = app_state.current_exercise();
            exercise.reset()?;
            println!("The exercise {exercise} has been reset!");
        }
        Some(Subcommands::Hint { name }) => {
            app_state.set_current_exercise_by_name(&name)?;
            println!("{}", app_state.current_exercise().hint);
        }
    }

    Ok(())
}

const CARGO_NOT_FOUND_ERR: &str = "Failed to find `cargo`.
Did you already install Rust?
Try running `cargo --version` to diagnose the problem.";

const PRE_INIT_MSG: &str = r"
       welcome to...
                 _   _ _
  _ __ _   _ ___| |_| (_)_ __   __ _ ___
 | '__| | | / __| __| | | '_ \ / _` / __|
 | |  | |_| \__ \ |_| | | | | | (_| \__ \
 |_|   \__,_|___/\__|_|_|_| |_|\__, |___/
                               |___/

The `exercises` directory wasn't found in the current directory.
If you are just starting with Rustlings, run the command `rustlings init` to initialize it.";

const POST_INIT_MSG: &str = "
Done initialization!

Run `cd rustlings` to go into the generated directory.
Then run `rustlings` for further instructions on getting started.";

const FENISH_LINE: &str = "+----------------------------------------------------+
|          You made it to the Fe-nish line!          |
+--------------------------  ------------------------+
                           \\/\x1b[31m
     ▒▒          ▒▒▒▒▒▒▒▒      ▒▒▒▒▒▒▒▒          ▒▒
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           ▒▒  ▒▒                      ▒▒  ▒▒\x1b[0m";