use crate::config::*;
use crate::corpus::*;
use crate::output::*;
use rand::prelude::*;
use std::fmt;

#[derive(Copy, Clone)]
pub struct Prelayout {
    standard_columns: [[char; 3]; 6],
    index_columns: [[char; 6]; 2],
}

impl Prelayout {
    pub fn get_standard_column(&self, index: usize) -> &[char; 3] {
        &self.standard_columns[index]
    }

    pub fn get_index_column(&self, index: usize) -> &[char; 6] {
        &self.index_columns[index]
    }

    pub fn new_random_from<R: RngCore>(pl: &Prelayout, rng: &mut R) -> Prelayout {
        let mut standard_columns = pl.standard_columns.clone();
        let mut index_columns = pl.index_columns.clone();

        let mut count = rng.gen_range(1..NUM_KEYS);
        while count > 0 {
            let source_index: bool = rng.gen();
            let target_index: bool = rng.gen();

            let saved;
            let target_col: usize;
            let target_idx: usize;
            if target_index {
                target_col = rng.gen_range(0..2);
                target_idx = rng.gen_range(0..6);
                saved = index_columns[target_col][target_idx];
            } else {
                target_col = rng.gen_range(0..6);
                target_idx = rng.gen_range(0..3);
                saved = standard_columns[target_col][target_idx];
            }

            let source_col: usize;
            let source_idx: usize;
            if source_index {
                source_col = rng.gen_range(0..2);
                source_idx = rng.gen_range(0..6);
                if target_index {
                    index_columns[target_col][target_idx] = index_columns[source_col][source_idx];
                } else {
                    standard_columns[target_col][target_idx] =
                        index_columns[source_col][source_idx];
                }
                index_columns[source_col][source_idx] = saved;
            } else {
                source_col = rng.gen_range(0..6);
                source_idx = rng.gen_range(0..3);
                if target_index {
                    index_columns[target_col][target_idx] =
                        standard_columns[source_col][source_idx];
                } else {
                    standard_columns[target_col][target_idx] =
                        standard_columns[source_col][source_idx];
                }
                standard_columns[source_col][source_idx] = saved;
            }
            count -= 1;
        }
        Prelayout {
            standard_columns,
            index_columns,
        }
    }

    fn from_char_array(ca: &[char; NUM_KEYS]) -> Prelayout {
        let mut standard_columns = [['x'; 3]; 6];
        let mut index_columns = [['x'; 6]; 2];

        for i in 0..6 {
            let ind = if i < 3 { i } else { i + 4 };
            for j in 0..3 {
                standard_columns[i][j] = ca[ind + j * ROW_LENGTH];
            }
        }

        for j in 0..3 {
            index_columns[0][j] = ca[3 + j * ROW_LENGTH];
            index_columns[1][j] = ca[6 + j * ROW_LENGTH];
            index_columns[0][j + 3] = ca[4 + j * ROW_LENGTH];
            index_columns[1][j + 3] = ca[5 + j * ROW_LENGTH];
        }

        Prelayout {
            standard_columns,
            index_columns,
        }
    }
}

#[derive(Copy, Clone)]
pub struct Layout {
    keys: [char; NUM_KEYS],
}

impl Layout {
    pub fn as_prelayout(&self) -> Prelayout {
        Prelayout::from_char_array(&self.keys)
    }

    pub fn from_prelayout(pl: &Prelayout, corpus: &Corpus) -> Layout {
        fn weight_function<const N: usize, const M: usize>(
            columns: &[[char; N]; M],
            corpus: &Corpus,
        ) -> Vec<(Vec<char>, u32)> {
            let mut result = columns
                .iter()
                .map(|col| {
                    let mut weight = 0;
                    let mut wcol: Vec<(char, u32)> = col
                        .iter()
                        .map(|&c| {
                            let w = corpus.get_character_count(c);
                            weight += w;
                            (c, w)
                        })
                        .collect();
                    wcol.sort_by(|(_, l), (_, r)| r.cmp(l));
                    wcol.swap(0, 1);
                    if N == 6 {
                        wcol.swap(3, 4);
                    }
                    (wcol.into_iter().map(|(k, _)| k).collect(), weight)
                })
                .collect::<Vec<(Vec<char>, u32)>>();
            result.sort_by(|(_, l), (_, r)| r.cmp(l));
            result
        }

        let mut balance: i64 = 0;
        let mut left_col: usize = 0;
        let mut right_col: usize = 9;
        let mut keys = ['x'; NUM_KEYS];

        let mut w_standard_columns = weight_function(&pl.standard_columns, corpus);
        while let Some((col, weight)) = w_standard_columns.pop() {
            let left: bool = ((balance >= 0) && (left_col <= 2)) || (right_col <= 6);
            let ind = if left { left_col } else { right_col };
            for i in 0..3 {
                keys[ind + i * ROW_LENGTH] = col[i];
            }
            if left {
                left_col += 1;
            } else {
                right_col -= 1;
            }
            balance += if left {
                -(weight as i64)
            } else {
                weight as i64
            };
        }

        let w_index_columns = weight_function(&pl.index_columns, corpus);
        let (left_ind, right_ind) = if balance >= 0 { (0, 1) } else { (1, 0) };
        for j in 0..3 {
            keys[3 + j * ROW_LENGTH] = w_index_columns[left_ind].0[j];
            keys[6 + j * ROW_LENGTH] = w_index_columns[right_ind].0[j];
            keys[4 + j * ROW_LENGTH] = w_index_columns[left_ind].0[j + 3];
            keys[5 + j * ROW_LENGTH] = w_index_columns[right_ind].0[j + 3];
        }

        Layout { keys }
    }

    pub fn get_keys(&self) -> &[char] {
        &self.keys
    }

    fn char_array_to_layout(keys: [char; NUM_KEYS]) -> Layout {
        return Layout { keys };
    }

    pub fn get_key(&self, index: usize) -> char {
        self.keys[index]
    }

    pub fn from_verbose(inp: &str) -> Option<Layout> {
        let mut layout: [char; NUM_KEYS] = ['x'; NUM_KEYS];

        let mut k: usize = 0;
        for c in inp.chars() {
            let valid = (c.is_uppercase() && c.is_alphabetic())
                || c == '.'
                || c == '/'
                || c == ','
                || c == '\'';
            if valid {
                layout[k] = c;
                k += 1;
            }
            if k > NUM_KEYS {
                return None;
            }
        }

        return Some(Layout::char_array_to_layout(layout));
    }
}

impl fmt::Display for Layout {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        formatter.write_str(&format_block_output(self.keys.into_iter()))
    }
}