// Dancing Droids
// Copyright (C) 2020  Martin HART, Volodymyr PATUTA, Stephane Elias BENABDESLAM
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.

use clap::{App, Arg};
use std::collections::HashMap;
use std::fs;
use std::io;

mod robot;
mod world;

/// Check if the robot is in the map.
fn check_map(r: &robot::Robot, w: &world::World) -> Result<(), String> {
    if (r.p.x, r.p.y) < (0, 0) || (r.p.x, r.p.y) > (w.x, w.y) {
        Err(format!("The robot {} is off map", r.id))
    } else {
        Ok(())
    }
}

/// Check if the robot collide with another one at the given position.
fn check_collisions(
    r: &robot::Robot,
    w: &world::World,
    h: &HashMap<&robot::Position, &u32>,
) -> Result<(), String> {
    match h.get(&r.p) {
        Some(&x) => Err(format!(
            "The robot id: {} collided with robot id: {} in position: ({};{}) !",
            &r.id, x, &r.p.x, &r.p.y
        )),
        None => Ok(()),
    }
}

/// Parse the config file, generate the world and robot pool.
fn parse_config(conf: String, pool: &mut Vec<robot::Robot>) -> Result<world::World, &'static str> {
    let mut lines = conf.lines();
    // The first line of the config file should be the World.
    let raw_line: &str = match lines.next() {
        Some(raw) => raw,
        None => return Err("Could not read the first line of the config file !"),
    };
    let mut tokens = raw_line.split_whitespace();
    let token1 = match tokens.next() {
        Some(raw) => raw,
        None => return Err("Could not read the first token of the first line !"),
    };
    let token2 = match tokens.next() {
        Some(raw) => raw,
        None => return Err("Could not read the second token of the first line !"),
    };
    let x: i32 = match token1.parse::<i32>() {
        Ok(x) => x,
        Err(_) => return Err("Could not convert token one from the first string to i32"),
    };
    let y: i32 = match token2.parse::<i32>() {
        Ok(x) => x,
        Err(_) => return Err("Could not convert token two from the first string to i32"),
    };
    loop {
        // This line should be empty.
        let empty_line = match lines.next() {
            None => break,
            Some(x) => x,
        };
        if !empty_line.is_empty() {
            return Err("This line should be empty !");
        }
        let raw_setup = match lines.next() {
            None => return Err("This line should be the config !"),
            Some(raw) => raw,
        };
        if raw_setup.is_empty() {
            return Err("This line should not be empty !");
        }
        let raw_inst = match lines.next() {
            None => return Err("This line should be the instruction !"),
            Some(raw) => raw,
        };
        if raw_inst.is_empty() {
            return Err("Thi line should not be empty !");
        }
        println!("{}", raw_setup);
        println!("{}", raw_inst);
    }
    Ok(world::World { x, y })
}

/// Retrieve the content of a file and return it as a string.
fn open_file(filename: &str) -> io::Result<String> {
    let content = fs::read_to_string(filename)?;
    Ok(content)
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // We handle CLI flags here.
    let matches = App::new("DancingDroids")
        .version("0.1.0")
        .about("When droids dance togethers")
        .arg(
            Arg::with_name("file")
                .short("f")
                .long("file")
                .takes_value(true)
                .help("Configuration file"),
        )
        .get_matches();

    let raw_conf = open_file(matches.value_of("file").unwrap_or("two_robots.txt"))?;

    let mut robot_pool: Vec<robot::Robot> = Vec::new();
    let world: world::World = parse_config(raw_conf, &mut robot_pool)?;

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_open_file() {
        assert!(open_file("two_robots.txt").is_ok());
        assert!(open_file("test_unexisting_file.extension").is_err());
    }

    #[test]
    fn test_check_map() {
        let mut r = robot::Robot::new(
            0,
            robot::Orientation::N,
            robot::Position { x: 2, y: 3 },
            vec!['F'],
        );
        let w = world::World { x: 10, y: 10 };

        assert!(check_map(&r, &w).is_ok());
    }

    #[test]
    #[should_panic]
    fn test_check_map_fail() {
        let mut r = robot::Robot::new(
            0,
            robot::Orientation::N,
            robot::Position { x: 2, y: 3 },
            vec!['F'],
        );
        let w = world::World { x: 1, y: 1 };

        assert!(check_map(&r, &w).is_ok());
    }

    #[test]
    #[should_panic]
    fn test_check_collisions() {
        let mut r = robot::Robot::new(
            0,
            robot::Orientation::N,
            robot::Position { x: 2, y: 3 },
            vec!['F'],
        );
        let w = world::World { x: 10, y: 10 };

        let mut h: HashMap<&robot::Position, &u32> = HashMap::new();
        h.insert(&robot::Position { x: 2, y: 3 }, &1);
        assert!(check_collisions(&r, &w, &h).is_ok());
    }
}