use std::collections::HashMap;

fn debug_log_to_file (message: String) {
    use std::fs::OpenOptions;
    use std::io::prelude::*;
    let mut file = OpenOptions::new().append(true).create(true).open("/tmp/mosaic-log.txt").unwrap();
    file.write_all(message.as_bytes()).unwrap();
    file.write_all("\n".as_bytes()).unwrap();
}

pub mod boundary_type {
    pub const TOP_RIGHT: &str = "┐";
    pub const VERTICAL: &str = "│";
    pub const HORIZONTAL: &str = "─";
    pub const TOP_LEFT: &str = "┌";
    pub const BOTTOM_RIGHT: &str = "┘";
    pub const BOTTOM_LEFT: &str = "└";
    pub const VERTICAL_LEFT: &str = "┤";
    pub const VERTICAL_RIGHT: &str = "├";
    pub const HORIZONTAL_DOWN: &str = "┬";
    pub const HORIZONTAL_UP: &str = "┴";
    pub const CROSS: &str = "┼";
}

pub type BoundaryType = &'static str; // easy way to refer to boundary_type above

fn combine_symbols(current_symbol: &str, next_symbol: &str) -> Option<&'static str> {
    match (current_symbol, next_symbol) {
        (boundary_type::TOP_RIGHT, boundary_type::TOP_RIGHT) => Some(boundary_type::TOP_RIGHT), // (┐, ┐) => Some(┐)
        (boundary_type::TOP_RIGHT, boundary_type::VERTICAL) => Some(boundary_type::VERTICAL_LEFT), // (┐, │) => Some(┤)
        (boundary_type::TOP_RIGHT, boundary_type::HORIZONTAL) => Some(boundary_type::HORIZONTAL_DOWN), // (┐, ─) => Some(┬)
        (boundary_type::TOP_RIGHT, boundary_type::TOP_LEFT) => Some(boundary_type::HORIZONTAL_DOWN), // (┐, ┌) => Some(┬)
        (boundary_type::TOP_RIGHT, boundary_type::BOTTOM_RIGHT) => Some(boundary_type::VERTICAL_LEFT), // (┐, ┘) => Some(┤)
        (boundary_type::TOP_RIGHT, boundary_type::BOTTOM_LEFT) => Some(boundary_type::CROSS), // (┐, └) => Some(┼)
        (boundary_type::TOP_RIGHT, boundary_type::VERTICAL_LEFT) => Some(boundary_type::VERTICAL_LEFT), // (┐, ┤) => Some(┤)
        (boundary_type::TOP_RIGHT, boundary_type::VERTICAL_RIGHT) => Some(boundary_type::CROSS), // (┐, ├) => Some(┼)
        (boundary_type::TOP_RIGHT, boundary_type::HORIZONTAL_DOWN) => Some(boundary_type::HORIZONTAL_DOWN), // (┐, ┬) => Some(┬)
        (boundary_type::TOP_RIGHT, boundary_type::HORIZONTAL_UP) => Some(boundary_type::CROSS), // (┐, ┴) => Some(┼)
        (boundary_type::TOP_RIGHT, boundary_type::CROSS) => Some(boundary_type::CROSS), // (┐, ┼) => Some(┼)

        (boundary_type::HORIZONTAL, boundary_type::HORIZONTAL) => Some(boundary_type::HORIZONTAL), // (─, ─) => Some(─)
        (boundary_type::HORIZONTAL, boundary_type::VERTICAL) => Some(boundary_type::CROSS), // (─, │) => Some(┼)
        (boundary_type::HORIZONTAL, boundary_type::TOP_LEFT) => Some(boundary_type::HORIZONTAL_DOWN), // (─, ┌) => Some(┬)
        (boundary_type::HORIZONTAL, boundary_type::BOTTOM_RIGHT) => Some(boundary_type::HORIZONTAL_UP), // (─, ┘) => Some(┴)
        (boundary_type::HORIZONTAL, boundary_type::BOTTOM_LEFT) => Some(boundary_type::HORIZONTAL_UP), // (─, └) => Some(┴)
        (boundary_type::HORIZONTAL, boundary_type::VERTICAL_LEFT) => Some(boundary_type::CROSS), // (─, ┤) => Some(┼)
        (boundary_type::HORIZONTAL, boundary_type::VERTICAL_RIGHT) => Some(boundary_type::CROSS), // (─, ├) => Some(┼)
        (boundary_type::HORIZONTAL, boundary_type::HORIZONTAL_DOWN) => Some(boundary_type::HORIZONTAL_DOWN), // (─, ┬) => Some(┬)
        (boundary_type::HORIZONTAL, boundary_type::HORIZONTAL_UP) => Some(boundary_type::HORIZONTAL_UP), // (─, ┴) => Some(┴)
        (boundary_type::HORIZONTAL, boundary_type::CROSS) => Some(boundary_type::CROSS), // (─, ┼) => Some(┼)

        (boundary_type::VERTICAL, boundary_type::VERTICAL) => Some(boundary_type::VERTICAL), // (│, │) => Some(│)
        (boundary_type::VERTICAL, boundary_type::TOP_LEFT) => Some(boundary_type::VERTICAL_RIGHT), // (│, ┌) => Some(├)
        (boundary_type::VERTICAL, boundary_type::BOTTOM_RIGHT) => Some(boundary_type::VERTICAL_LEFT), // (│, ┘) => Some(┤)
        (boundary_type::VERTICAL, boundary_type::BOTTOM_LEFT) => Some(boundary_type::VERTICAL_RIGHT), // (│, └) => Some(├)
        (boundary_type::VERTICAL, boundary_type::VERTICAL_LEFT) => Some(boundary_type::VERTICAL_LEFT), // (│, ┤) => Some(┤)
        (boundary_type::VERTICAL, boundary_type::VERTICAL_RIGHT) => Some(boundary_type::VERTICAL_RIGHT), // (│, ├) => Some(├)
        (boundary_type::VERTICAL, boundary_type::HORIZONTAL_DOWN) => Some(boundary_type::CROSS), // (│, ┬) => Some(┼)
        (boundary_type::VERTICAL, boundary_type::HORIZONTAL_UP) => Some(boundary_type::CROSS), // (│, ┴) => Some(┼)
        (boundary_type::VERTICAL, boundary_type::CROSS) => Some(boundary_type::CROSS), // (│, ┼) => Some(┼)

        (boundary_type::TOP_LEFT, boundary_type::TOP_LEFT) => Some(boundary_type::TOP_LEFT), // (┌, ┌) => Some(┌)
        (boundary_type::TOP_LEFT, boundary_type::BOTTOM_RIGHT) => Some(boundary_type::CROSS), // (┌, ┘) => Some(┼)
        (boundary_type::TOP_LEFT, boundary_type::BOTTOM_LEFT) => Some(boundary_type::VERTICAL_RIGHT), // (┌, └) => Some(├)
        (boundary_type::TOP_LEFT, boundary_type::VERTICAL_LEFT) => Some(boundary_type::CROSS), // (┌, ┤) => Some(┼)
        (boundary_type::TOP_LEFT, boundary_type::VERTICAL_RIGHT) => Some(boundary_type::VERTICAL_RIGHT), // (┌, ├) => Some(├)
        (boundary_type::TOP_LEFT, boundary_type::HORIZONTAL_DOWN) => Some(boundary_type::HORIZONTAL_DOWN), // (┌, ┬) => Some(┬)
        (boundary_type::TOP_LEFT, boundary_type::HORIZONTAL_UP) => Some(boundary_type::CROSS), // (┌, ┴) => Some(┼)
        (boundary_type::TOP_LEFT, boundary_type::CROSS) => Some(boundary_type::CROSS), // (┌, ┼) => Some(┼)

        (boundary_type::BOTTOM_RIGHT, boundary_type::BOTTOM_RIGHT) => Some(boundary_type::BOTTOM_RIGHT), // (┘, ┘) => Some(┘)
        (boundary_type::BOTTOM_RIGHT, boundary_type::BOTTOM_LEFT) => Some(boundary_type::HORIZONTAL_UP), // (┘, └) => Some(┴)
        (boundary_type::BOTTOM_RIGHT, boundary_type::VERTICAL_LEFT) => Some(boundary_type::VERTICAL_LEFT), // (┘, ┤) => Some(┤)
        (boundary_type::BOTTOM_RIGHT, boundary_type::VERTICAL_RIGHT) => Some(boundary_type::CROSS), // (┘, ├) => Some(┼)
        (boundary_type::BOTTOM_RIGHT, boundary_type::HORIZONTAL_DOWN) => Some(boundary_type::CROSS), // (┘, ┬) => Some(┼)
        (boundary_type::BOTTOM_RIGHT, boundary_type::HORIZONTAL_UP) => Some(boundary_type::HORIZONTAL_UP), // (┘, ┴) => Some(┴)
        (boundary_type::BOTTOM_RIGHT, boundary_type::CROSS) => Some(boundary_type::CROSS), // (┘, ┼) => Some(┼)

        (boundary_type::BOTTOM_LEFT, boundary_type::BOTTOM_LEFT) => Some(boundary_type::BOTTOM_LEFT), // (└, └) => Some(└)
        (boundary_type::BOTTOM_LEFT, boundary_type::VERTICAL_LEFT) => Some(boundary_type::CROSS), // (└, ┤) => Some(┼)
        (boundary_type::BOTTOM_LEFT, boundary_type::VERTICAL_RIGHT) => Some(boundary_type::VERTICAL_RIGHT), // (└, ├) => Some(├)
        (boundary_type::BOTTOM_LEFT, boundary_type::HORIZONTAL_DOWN) => Some(boundary_type::CROSS), // (└, ┬) => Some(┼)
        (boundary_type::BOTTOM_LEFT, boundary_type::HORIZONTAL_UP) => Some(boundary_type::HORIZONTAL_UP), // (└, ┴) => Some(┴)
        (boundary_type::BOTTOM_LEFT, boundary_type::CROSS) => Some(boundary_type::CROSS), // (└, ┼) => Some(┼)

        (boundary_type::VERTICAL_LEFT, boundary_type::VERTICAL_LEFT) => Some(boundary_type::VERTICAL_LEFT), // (┤, ┤) => Some(┤)
        (boundary_type::VERTICAL_LEFT, boundary_type::VERTICAL_RIGHT) => Some(boundary_type::CROSS), // (┤, ├) => Some(┼)
        (boundary_type::VERTICAL_LEFT, boundary_type::HORIZONTAL_DOWN) => Some(boundary_type::CROSS), // (┤, ┬) => Some(┼)
        (boundary_type::VERTICAL_LEFT, boundary_type::HORIZONTAL_UP) => Some(boundary_type::HORIZONTAL_UP), // (┤, ┴) => Some(┼)
        (boundary_type::VERTICAL_LEFT, boundary_type::CROSS) => Some(boundary_type::CROSS), // (┤, ┼) => Some(┼)

        (boundary_type::VERTICAL_RIGHT, boundary_type::VERTICAL_RIGHT) => {
            Some(boundary_type::VERTICAL_RIGHT)
        } // (├, ├) => Some(├)
        (boundary_type::VERTICAL_RIGHT, boundary_type::HORIZONTAL_DOWN) => Some(boundary_type::CROSS), // (├, ┬) => Some(┼)
        (boundary_type::VERTICAL_RIGHT, boundary_type::HORIZONTAL_UP) => Some(boundary_type::CROSS), // (├, ┴) => Some(┼)
        (boundary_type::VERTICAL_RIGHT, boundary_type::CROSS) => Some(boundary_type::CROSS), // (├, ┼) => Some(┼)

        (boundary_type::HORIZONTAL_DOWN, boundary_type::HORIZONTAL_DOWN) => {
            Some(boundary_type::HORIZONTAL_DOWN)
        } // (┬, ┬) => Some(┬)
        (boundary_type::HORIZONTAL_DOWN, boundary_type::HORIZONTAL_UP) => Some(boundary_type::CROSS), // (┬, ┴) => Some(┼)
        (boundary_type::HORIZONTAL_DOWN, boundary_type::CROSS) => Some(boundary_type::CROSS), // (┬, ┼) => Some(┼)

        (boundary_type::HORIZONTAL_UP, boundary_type::HORIZONTAL_UP) => Some(boundary_type::HORIZONTAL_UP), // (┴, ┴) => Some(┴)
        (boundary_type::HORIZONTAL_UP, boundary_type::CROSS) => Some(boundary_type::CROSS), // (┴, ┼) => Some(┼)

        (boundary_type::CROSS, boundary_type::CROSS) => Some(boundary_type::CROSS), // (┼, ┼) => Some(┼)

        (_, _) => None,
    }
}

fn find_next_symbol(first_symbol: &str, second_symbol: &str) -> Option<&'static str> {
    if let Some(symbol) = combine_symbols(first_symbol, second_symbol) {
        Some(symbol)
    } else {
        combine_symbols(second_symbol, first_symbol)
    }
}

#[derive(PartialEq, Eq, Hash, Debug)]
pub struct Coordinates {
    x: usize,
    y: usize,
}

impl Coordinates {
    pub fn new(x: usize, y: usize) -> Self {
        Coordinates {x, y}
    }
}

pub trait Rect {
    fn x(&self) -> usize;
    fn y(&self) -> usize;
    fn rows(&self) -> usize;
    fn columns(&self) -> usize;
    fn right_boundary_x_coords (&self) -> usize {
        self.x() + self.columns()
    }
    fn bottom_boundary_y_coords (&self) -> usize {
        self.y() + self.rows()
    }
}

pub struct Boundaries {
    columns: usize,
    rows: usize,
    boundary_characters: HashMap<Coordinates, BoundaryType>,
}

impl Boundaries {
    pub fn new(columns: u16, rows: u16) -> Self {
        let columns = columns as usize;
        let rows = rows as usize;
        Boundaries {
            columns,
            rows,
            boundary_characters: HashMap::new(),
        }
    }
    pub fn add_rect(&mut self, rect: &dyn Rect) {
        if self.rect_right_boundary_is_before_screen_edge(rect) {
            // let boundary_x_coords = self.rect_right_boundary_x_coords(rect);
            let boundary_x_coords = rect.right_boundary_x_coords();
            let first_row_coordinates = self.rect_right_boundary_row_start(rect);
            let last_row_coordinates = self.rect_right_boundary_row_end(rect);
            for row in first_row_coordinates..last_row_coordinates {
                let coordinates = Coordinates::new(boundary_x_coords, row);
                let symbol_to_add = if row == first_row_coordinates && row != 0 {
                    boundary_type::TOP_RIGHT
                } else if row == last_row_coordinates - 1 && row != self.rows - 1 {
                    boundary_type::BOTTOM_RIGHT
                } else {
                    boundary_type::VERTICAL
                };
                let next_symbol = self.boundary_characters.get(&coordinates)
                    .and_then(|current_symbol| find_next_symbol(current_symbol, symbol_to_add))
                    .unwrap_or(symbol_to_add);
                self.boundary_characters.insert(coordinates, next_symbol);
            }
        }
        if self.rect_bottom_boundary_is_before_screen_edge(rect) {
            let boundary_y_coords = rect.bottom_boundary_y_coords();
            let first_col_coordinates = self.rect_bottom_boundary_col_start(rect);
            let last_col_coordinates = self.rect_bottom_boundary_col_end(rect);
            for col in first_col_coordinates..last_col_coordinates {
                let coordinates = Coordinates::new(col, boundary_y_coords);
                let symbol_to_add = if col == first_col_coordinates && col != 0 {
                    boundary_type::BOTTOM_LEFT
                } else if col == last_col_coordinates - 1 && col != self.columns - 1 {
                    boundary_type::BOTTOM_RIGHT
                } else {
                    boundary_type::HORIZONTAL
                };
                let next_symbol = self.boundary_characters.get(&coordinates)
                    .and_then(|current_symbol| find_next_symbol(current_symbol, symbol_to_add))
                    .unwrap_or(symbol_to_add);
                self.boundary_characters.insert(coordinates, next_symbol);
            }
        }
    }
    pub fn vte_output (&self) -> String {
        let mut vte_output = String::new();
        for (coordinates, boundary_character) in &self.boundary_characters {
            vte_output.push_str(&format!("\u{1b}[{};{}H\u{1b}[m{}", coordinates.y + 1, coordinates.x + 1, boundary_character)); // goto row/col + boundary character
        }
        vte_output
    }
    fn rect_right_boundary_is_before_screen_edge (&self, rect: &dyn Rect) -> bool {
        rect.x() + rect.columns() < self.columns
    }
    fn rect_bottom_boundary_is_before_screen_edge(&self, rect: &dyn Rect) -> bool {
        rect.y() + rect.rows() < self.rows
    }
    fn rect_right_boundary_row_start(&self, rect: &dyn Rect) -> usize {
        if rect.y() == 0 { 0 } else { rect.y() - 1 }
    }
    fn rect_right_boundary_row_end(&self, rect: &dyn Rect) -> usize {
        let rect_bottom_row = rect.y() + rect.rows();
        // we do this because unless we're on the screen edge, we'd like to go one extra row to
        // connect to whatever boundary is beneath us
        if rect_bottom_row == self.rows { rect_bottom_row } else { rect_bottom_row + 1 }
    }
    fn rect_bottom_boundary_col_start(&self, rect: &dyn Rect) -> usize {
        if rect.x() == 0 { 0 } else { rect.x() - 1 }
    }
    fn rect_bottom_boundary_col_end(&self, rect: &dyn Rect) -> usize {
        let rect_right_col = rect.x() + rect.columns();
        // we do this because unless we're on the screen edge, we'd like to go one extra column to
        // connect to whatever boundary is right of us
        if rect_right_col == self.columns { rect_right_col } else { rect_right_col + 1 }
    }
}