use std::collections::HashSet;
use std::fmt;
use std::fmt::{Formatter, Write};
use std::str::FromStr;

pub const GRID_LENGTH: u8 = 15;
pub const TRAY_LENGTH: u8 = 7;
pub const ALL_LETTERS_BONUS: u32 = 50;

#[derive(Clone, Copy)]
enum Direction {
    Row, Column
}

impl Direction {
    fn invert(&self) -> Self {
        match &self {
            Direction::Row => {Direction::Column}
            Direction::Column => {Direction::Row}
        }
    }
}

#[derive(Clone, Copy, Debug)]
pub struct Coordinates (pub u8, pub u8);

impl Coordinates {
    fn add(&self, direction: Direction, i: i8) -> Option<Self> {
        let proposed = match direction {
            Direction::Column => {(self.0 as i8, self.1 as i8+i)}
            Direction::Row => {(self.0 as i8+i, self.1 as i8)}
        };

        if proposed.0 < 0 || proposed.0 >= GRID_LENGTH as i8 || proposed.1 < 0 || proposed.1 >= GRID_LENGTH as i8 {
            None
        } else{
            Some(Coordinates(proposed.0 as u8, proposed.1 as u8))
        }
    }

    fn increment(&self, direction: Direction) -> Option<Self>{
        self.add(direction, 1)
    }

    fn decrement(&self, direction: Direction) -> Option<Self>{
        self.add(direction, -1)
    }

    fn map_to_index(&self) -> usize {
        (self.0 + GRID_LENGTH*self.1) as usize
    }
}

#[derive(Debug)]
pub struct Letter {
    text: char,
    points: u32,
    ephemeral: bool,
    is_blank: bool,
}

impl Letter {
    pub fn new_fixed(text: char, points: u32) -> Self {
        Letter {
            text,
            points,
            ephemeral: false,
            is_blank: false,
        }
    }
}

#[derive(Debug)]
pub enum CellType {
    Normal,
    DoubleWord,
    DoubleLetter,
    TripleLetter,
    TripleWord,
    Start,
}

#[derive(Debug)]
pub struct Cell {
    pub value: Option<Letter>,
    cell_type: CellType,
    coordinates: Coordinates,
}


pub struct Dictionary {
    words: Vec<String>,
    scores: Vec<f64>,
}

impl Dictionary {
    fn new() -> Self {
        let mut reader = csv::Reader::from_path("resources/dictionary.csv").unwrap();
        let mut words: Vec<String> = Vec::new();
        let mut scores: Vec<f64> = Vec::new();

        for result in reader.records() {
            let record = result.unwrap();
            words.push(record.get(0).unwrap().to_string());
            let score = record.get(1).unwrap();
            scores.push(f64::from_str(score).unwrap());

        }

        Dictionary {
            words,
            scores,
        }
    }

    fn filter_to_sub_dictionary(&self, proportion: f64) -> Self {
        let mut words: Vec<String> = Vec::new();
        let mut scores: Vec<f64> = Vec::new();

        for (word, score) in self.words.iter().zip(self.scores.iter()) {
            if *score >= proportion {
                words.push(word.clone());
                scores.push(*score);
            }
        }

        Dictionary {words, scores}
    }

    fn substring_set(&self) -> HashSet<&str> {
        let mut set = HashSet::new();

        for word in self.words.iter() {
            for j in 0..word.len() {
                for k in (j+1)..(word.len()+1) {
                    set.insert(&word[j..k]);
                }
            }

        }

        set
    }


}


#[derive(Debug)]
pub struct Board {
    cells: Vec<Cell>,
}

struct Word<'a> {
    cells: Vec<&'a Cell>,
    coords: Coordinates,
}

impl Board {
    pub fn new() -> Self {
        let mut cells = Vec::new();


        /// Since the board is symmetrical in both directions for the purposes of our logic we can keep our coordinates in one corner
        ///
        /// # Arguments
        ///
        /// * `x`: A coordinate
        ///
        /// returns: u8 The coordinate mapped onto the lower-half
        fn map_to_corner(x: u8) -> u8 {
            return if x > GRID_LENGTH / 2 {
                GRID_LENGTH - x - 1
            } else {
                x
            }
        }

        for i_orig in 0..GRID_LENGTH {
            let i = map_to_corner(i_orig);
            for j_orig in 0..GRID_LENGTH {
                let j = map_to_corner(j_orig);

                let mut typee = CellType::Normal;

                // double word scores are diagonals
                if i == j {
                    typee = CellType::DoubleWord;
                }

                // Triple letters
                if (i % 4 == 1) && j % 4 == 1 && !(i == 1 && j == 1) {
                    typee = CellType::TripleLetter;
                }

                // Double letters
                if (i % 4 == 2) && (j % 4 == 2) && !(
                    i == 2 && j == 2
                ) {
                    typee = CellType::DoubleLetter;
                }
                if (i.min(j) == 0 && i.max(j) == 3) || (i.min(j)==3 && i.max(j) == 7) {
                    typee = CellType::DoubleLetter;
                }

                // Triple word scores
                if (i % 7 == 0) && (j % 7 == 0) {
                    typee = CellType::TripleWord;
                }

                // Start
                if i == 7 && j == 7 {
                    typee = CellType::Start;
                }

                cells.push(Cell {
                    cell_type: typee,
                    value: None,
                    coordinates: Coordinates(i, j),
                })

            }
        }

        Board {cells}
    }

    pub fn get_cell(&self, coordinates: Coordinates) -> Result<&Cell, &str> {
        if coordinates.0 >= GRID_LENGTH || coordinates.1 >= GRID_LENGTH {
            Err("x & y must be within the board's coordinates")
        } else {
            let index = coordinates.map_to_index();
            Ok(self.cells.get(index).unwrap())
        }
    }

    pub fn get_cell_mut(&mut self, coordinates: Coordinates) -> Result<&mut Cell, &str> {
        if coordinates.0 >= GRID_LENGTH || coordinates.1 >= GRID_LENGTH {
            Err("x & y must be within the board's coordinates")
        } else {
            let index = coordinates.map_to_index();
            Ok(self.cells.get_mut(index).unwrap())
        }
    }

    pub fn score_move(&self) -> Result<u32, &str> {
        // We don't assume that the move is valid, so let's first establish that


        // Let's first establish what rows and columns tiles were played in
        let mut rows_played = HashSet::with_capacity(15);
        let mut columns_played = HashSet::with_capacity(15);
        let mut tiles_played = 0;

        for x in 0..GRID_LENGTH {
            for y in 0..GRID_LENGTH {
                let coords = Coordinates(x, y);
                let cell = self.get_cell(coords).unwrap();
                match &cell.value {
                    Some(value) => {
                       if value.ephemeral {
                           rows_played.insert(x);
                           columns_played.insert(y);
                           tiles_played += 1;
                       }
                    }
                    _ => {}
                }
            }
        }

        if rows_played.is_empty() {
            return Err("Tiles need to be played")
        } else if rows_played.len() > 1 && columns_played.len() > 1 {
            return Err("Tiles need to be played on one row or column")
        }

        let direction = if rows_played.len() > 1 {
            Direction::Column
        } else {
            Direction::Row
        };

        let starting_row = *rows_played.iter().min().unwrap();
        let starting_column = *columns_played.iter().min().unwrap();

        let mut starting_coords = Coordinates(starting_row, starting_column);



        // At this point we now know that we're at the start of the word and we have the direction.
        // Now we'll head forward and look for every word that intersects one of the played tiles



        todo!()
    }

    fn find_word(&self, mut start_coords: Coordinates, direction: Direction) -> Option<Word> {
        // let's see how far we can backtrack to the start of the word
        let mut times_moved = 0;
        loop {
            let one_back = start_coords.add(direction, -times_moved);
            match one_back {
                None => { break }
                Some(new_coords) => {
                    let cell = self.get_cell(new_coords).unwrap();
                    if cell.value.is_some(){
                        times_moved += 1;
                    } else {
                        break
                    }
                }
            }
        }

        if times_moved == 0 {
            return None;
        }

        start_coords = start_coords.add(direction, -times_moved + 1).unwrap();

        // since we moved and we know that start_coords has started on a letter, we know we have a word
        // we'll now keep track of the cells that form it
        let mut cells = Vec::with_capacity(GRID_LENGTH as usize);
        cells.push(self.get_cell(start_coords).unwrap());

        loop {
            let position = start_coords.add(direction, cells.len() as i8);
            match position {
                None => {break}
                Some(x) => {
                    let cell = self.get_cell(x).unwrap();
                    match cell.value {
                        None => {break}
                        Some(_) => {
                            cells.push(cell);
                        }
                    }
                }
            }
        }

        Some(Word {
            cells,
            coords: start_coords,
        })
    }


}

impl fmt::Display for Board {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {

        let mut str = String::new();

        let normal = "\x1b[48;5;174m\x1b[38;5;0m";
        let triple_word = "\x1b[48;5;196m\x1b[38;5;0m";
        let double_word = "\x1b[48;5;204m\x1b[38;5;0m";
        let triple_letter = "\x1b[48;5;21m\x1b[38;5;15m";
        let double_letter = "\x1b[48;5;51m\x1b[38;5;0m";
        str.write_char('\n').unwrap();

        for x in 0..GRID_LENGTH {
            for y in 0..GRID_LENGTH {
                let coords = Coordinates(x, y);

                let cell = self.get_cell(coords).unwrap();

                let color = match cell.cell_type {
                    CellType::Normal => {normal}
                    CellType::DoubleWord => {double_word}
                    CellType::DoubleLetter => {double_letter}
                    CellType::TripleLetter => {triple_letter}
                    CellType::TripleWord => {triple_word}
                    CellType::Start => {double_word}
                };

                let content = match &cell.value {
                    None => {' '}
                    Some(letter) => {letter.text}
                };


                str.write_str(color).unwrap();
                str.write_char(content).unwrap();


            }
            str.write_str("\x1b[0m\n").unwrap();
        }

        write!(f, "{}", str)

    }
}



#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_cell_types() {
        let board = Board::new();

        assert!(matches!(board.get_cell(Coordinates(0, 0)).unwrap().cell_type, CellType::TripleWord));
        assert!(matches!(board.get_cell(Coordinates(1, 0)).unwrap().cell_type, CellType::Normal));
        assert!(matches!(board.get_cell(Coordinates(0, 1)).unwrap().cell_type, CellType::Normal));
        assert!(matches!(board.get_cell(Coordinates(1, 1)).unwrap().cell_type, CellType::DoubleWord));

        assert!(matches!(board.get_cell(Coordinates(13, 13)).unwrap().cell_type, CellType::DoubleWord));
        assert!(matches!(board.get_cell(Coordinates(14, 14)).unwrap().cell_type, CellType::TripleWord));
        assert!(matches!(board.get_cell(Coordinates(11, 14)).unwrap().cell_type, CellType::DoubleLetter));

        assert!(matches!(board.get_cell(Coordinates(7, 7)).unwrap().cell_type, CellType::Start));
        assert!(matches!(board.get_cell(Coordinates(8, 6)).unwrap().cell_type, CellType::DoubleLetter));
        assert!(matches!(board.get_cell(Coordinates(5, 9)).unwrap().cell_type, CellType::TripleLetter));
    }

    #[test]
    fn test_word_finding() {
        let mut board = Board::new();

        board.get_cell_mut(Coordinates(8, 6)).unwrap().value = Some(Letter::new_fixed('J', 0));
        board.get_cell_mut(Coordinates(8, 7)).unwrap().value = Some(Letter::new_fixed('O', 0));
        board.get_cell_mut(Coordinates(8, 8)).unwrap().value = Some(Letter::new_fixed( 'E', 0));
        board.get_cell_mut(Coordinates(8, 9)).unwrap().value = Some(Letter::new_fixed( 'L', 0));

        board.get_cell_mut(Coordinates(0, 0)).unwrap().value = Some(Letter::new_fixed('I', 0));
        board.get_cell_mut(Coordinates(1, 0)).unwrap().value = Some(Letter::new_fixed('S', 0));

        board.get_cell_mut(Coordinates(3, 0)).unwrap().value = Some(Letter::new_fixed('C', 0));
        board.get_cell_mut(Coordinates(4, 0)).unwrap().value = Some(Letter::new_fixed('O', 0));
        board.get_cell_mut(Coordinates(5, 0)).unwrap().value = Some(Letter::new_fixed('O', 0));
        board.get_cell_mut(Coordinates(6, 0)).unwrap().value = Some(Letter::new_fixed('L', 0));


        board.get_cell_mut(Coordinates(9, 8)).unwrap().value = Some(Letter::new_fixed( 'G', 0));
        board.get_cell_mut(Coordinates(10, 8)).unwrap().value = Some(Letter::new_fixed( 'G', 0));

        fn word_to_text(word: Word) -> String {
            let mut text = String::with_capacity(word.cells.len());
            for cell in word.cells {
                text.push(cell.value.as_ref().unwrap().text);
            }

            text
        }

        for x in vec![6, 7, 8, 9] {
            println!("x is {}", x);
            let first_word = board.find_word(Coordinates(8, x), Direction::Column);
            match first_word {
                None => {panic!("Expected to find word JOEL")}
                Some(x) => {
                    assert_eq!(x.coords.0, 8);
                    assert_eq!(x.coords.1, 6);

                    assert_eq!(word_to_text(x), "JOEL");

                }
            }
        }

        let single_letter_word = board.find_word(Coordinates(8, 9), Direction::Row);
        match single_letter_word {
            None => {panic!("Expected to find letter L")}
            Some(x) => {
                assert_eq!(x.coords.0, 8);
                assert_eq!(x.coords.1, 9);

                assert_eq!(word_to_text(x), "L");
            }
        }

        for x in vec![0, 1] {
            println!("x is {}", x);
            let word = board.find_word(Coordinates(x, 0), Direction::Row);
            match word {
                None => {panic!("Expected to find word IS")}
                Some(x) => {
                    assert_eq!(x.coords.0, 0);
                    assert_eq!(x.coords.1, 0);

                    assert_eq!(word_to_text(x), "IS");

                }
            }
        }

        for x in vec![3, 4, 5, 6] {
            println!("x is {}", x);
            let word = board.find_word(Coordinates(x, 0), Direction::Row);
            match word {
                None => {panic!("Expected to find word COOL")}
                Some(x) => {
                    assert_eq!(x.coords.0, 3);
                    assert_eq!(x.coords.1, 0);

                    assert_eq!(word_to_text(x), "COOL");

                }
            }
        }

        let no_word = board.find_word(Coordinates(2, 0), Direction::Row);
        assert!(no_word.is_none());

        let word = board.find_word(Coordinates(10, 8), Direction::Row);
        match word {
            None => {panic!("Expected to find word EGG")}
            Some(x) => {
                assert_eq!(x.coords.0, 8);
                assert_eq!(x.coords.1, 8);

                assert_eq!(word_to_text(x), "EGG");

            }
        }



    }

    #[test]
    fn test_dictionary() {
        let dictionary = Dictionary::new();

        assert_eq!(dictionary.words.len(), dictionary.scores.len());
        assert_eq!(dictionary.words.len(), 279429);

        assert_eq!(dictionary.words.get(0).unwrap(), "AA");
        assert_eq!(dictionary.words.get(9).unwrap(), "AARDVARK");

        assert!((dictionary.scores.get(9).unwrap() - 0.5798372).abs() < 0.0001)

    }

    #[test]
    fn test_dictionary_sets() {
        let dictionary = Dictionary {
            words: vec!["JOEL".to_string(), "JOHN".to_string(), "XYZ".to_string()],
            scores: vec![0.7, 0.5, 0.1],
        };

        let dictionary = dictionary.filter_to_sub_dictionary(0.3);
        assert_eq!(dictionary.words.len(), 2);
        assert_eq!(dictionary.words.get(0).unwrap(), "JOEL");
        assert_eq!(dictionary.words.get(1).unwrap(), "JOHN");

        let set = dictionary.substring_set();

        assert!(set.contains("J"));
        assert!(set.contains("O"));
        assert!(set.contains("E"));
        assert!(set.contains("L"));
        assert!(set.contains("H"));
        assert!(set.contains("N"));

        assert!(set.contains("JO"));
        assert!(set.contains("OE"));
        assert!(set.contains("EL"));
        assert!(set.contains("OH"));
        assert!(set.contains("HN"));

        assert!(set.contains("JOE"));
        assert!(set.contains("OEL"));
        assert!(set.contains("JOH"));
        assert!(set.contains("OHN"));


        assert!(!set.contains("XY"));
        assert!(!set.contains("JH"));
        assert!(!set.contains("JE"));

    }
}