//! Editor functionality
use crate::terminal_helpers::*;

use std::cmp::PartialEq;
use std::fs::File;
use std::io;
use std::io::prelude::*;
use std::io::BufReader;
use std::ops::Range;
use std::time::{Duration, Instant};

use self::KeyCode::*;

// ------------------------------------------------------------------------
// Defines
// ------------------------------------------------------------------------

const KILO_TAB_STOP: usize = 4;
const KILO_QUIT_TIMES: u8 = 3;

// ------------------------------------------------------------------------
// Data
// ------------------------------------------------------------------------

// Use an external package's macro to create a memory-safe
// bit flag alternative
bitflags! {
    #[derive(Default)]
    pub struct SyntaxFlags: u32 {
        const HIGHLIGHT_NUMBERS = 0b00000001;
        const HIGHLIGHT_STRINGS = 0b00000010;
    }
}

/// Configuration for language syntax highlighting
#[derive(Clone, Debug, Default, PartialEq)]
pub struct Syntax {
    /// Language name, to be shown in status bar
    file_type: String,

    /// File extensions
    file_match: Vec<&'static str>,

    /// Keywords
    keywords1: Vec<&'static str>,

    /// Type and/or secondary keywords
    keywords2: Vec<&'static str>,

    /// How does a single line comment start?
    singleline_comment_start: String,

    /// How does a multline comment start?
    multiline_comment_start: String,

    /// How does a multiline comment end?
    multiline_comment_end: String,

    /// Options for what to highlight
    flags: SyntaxFlags,
}

/// Syntax highlighting token types
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum Highlight {
    /// No highlighting
    Normal,

    /// Single line comments
    LineComment,

    /// Multiple line comments
    MultiLineComment,

    /// Language keywords
    Keyword1,

    /// Language types/ secondary keywords
    Keyword2,

    /// Single-line strings
    String,

    /// Numbers
    Number,

    /// Search results
    SearchMatch,
}

/// A representation of a line in the editor
#[derive(Clone, Debug, Default)]
pub struct Row {
    /// The 'raw' representation of the original characters
    chars: String,

    /// The display characters for the editor
    render: String,

    /// The highlighting type for each character
    highlight: Vec<Highlight>,

    /// Are we currently highlighting a multi-line comment?
    highlight_comment_start: bool,
}

/// Main structure for the editor
/// `EditorConfig` struct in C version
#[derive(Debug)]
pub struct Editor {
    cursor_x: usize,
    cursor_y: usize,
    render_x: usize,
    col_offset: usize,
    row_offset: usize,
    screen_cols: usize,
    screen_rows: usize,
    rows: Vec<Row>,
    dirty: u64,
    filename: String,
    status_message: String,
    status_message_time: Instant,
    syntax: Option<Syntax>,

    // Properties not present in C version
    output_buffer: String,
    quit_times: u8,
    search_last_match: i32,
    search_direction: i8,
    search_last_line: usize,
    search_last_hightlight: Vec<Highlight>,
}

/// Keycode mapping enum
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum KeyCode<T> {
    Enter,
    Escape,
    Backspace,
    ArrowLeft,
    ArrowRight,
    ArrowUp,
    ArrowDown,
    DeleteKey,
    HomeKey,
    EndKey,
    PageUp,
    PageDown,
    /// Function keys (F1, etc.) T holds the index
    Function(T),
    /// Any other type of character
    OtherKey(T),
}

impl Syntax {
    pub fn new(
        file_type: &str,
        file_match: Vec<&'static str>,
        keywords1: Vec<&'static str>,
        keywords2: Vec<&'static str>,
        single_line_comment_start: &str,
        multi_line_comment_start: &str,
        multi_line_comment_end: &str,
        flags: SyntaxFlags,
    ) -> Self {
        Syntax {
            file_type: file_type.to_owned(),
            file_match,
            keywords1,
            keywords2,
            singleline_comment_start: single_line_comment_start.to_owned(),
            multiline_comment_start: multi_line_comment_start.to_owned(),
            multiline_comment_end: multi_line_comment_end.to_owned(),
            flags,
        }
    }
}

impl Row {
    pub fn new(chars: &str) -> Self {
        let mut instance = Row::default();
        instance.chars = chars.to_owned();

        instance
    }
}

impl KeyCode<char> {
    pub fn unwrap(self) -> char {
        match self {
            self::OtherKey(val) => val,
            _ => panic!("called `KeyCode::unwrap()` on a `None` value"),
        }
    }
}

impl Default for Editor {
    fn default() -> Self {
        Editor {
            cursor_x: 0,
            cursor_y: 0,
            render_x: 0,
            col_offset: 0,
            row_offset: 0,
            screen_cols: 0,
            screen_rows: 0,
            rows: vec![],
            dirty: 0,
            filename: String::new(),
            status_message: String::new(),

            // This is the only reason I had to implement this method
            // manually, instead of it being derived. Apparently an
            // `Instant` struct has no default
            status_message_time: Instant::now(),

            syntax: None,

            output_buffer: String::new(),
            quit_times: KILO_QUIT_TIMES,
            search_last_match: -1,
            search_direction: 1,
            search_last_line: 0,
            search_last_hightlight: vec![],
        }
    }
}

impl Editor {
    // ------------------------------------------------------------------------
    // Init
    // ------------------------------------------------------------------------

    pub fn new() -> Self {
        let mut instance = Self::default();

        let size = instance.get_window_size();

        instance.screen_cols = size.cols as usize;
        instance.screen_rows = (size.rows - 2) as usize;

        instance
    }

    // ------------------------------------------------------------------------
    // Terminal
    // ------------------------------------------------------------------------

    /// Convert stdin to specific keypresses
    fn read_key(&mut self) -> Option<KeyCode<char>> {
        // --------------------------------------------------------------------
        // Match single character
        // --------------------------------------------------------------------
        let stdin = io::stdin();
        let stdin = stdin.lock();
        let mut br = BufReader::with_capacity(5, stdin);

        let mut first_read = [0; 1];
        match br.read_exact(&mut first_read) {
            Ok(_) => (),
            Err(e) => {
                if e.kind() != io::ErrorKind::UnexpectedEof {
                    let error = format!("{:?}", e);
                    self.set_status_message(&error);
                }
            }
        }
        let first_str = String::from_utf8(first_read.to_vec());
        if first_str.is_err() {
            return None;
        }
        let first_str = first_str.unwrap();

        // Read the first character, if it isn't escape, just return it
        let mut chs = first_str.chars();
        let ch = chs.next();
        match ch {
            Some(ch) => match ch {
                '\0' => return None,
                '\x1b' => (),
                '\x08' => return Some(Backspace),
                '\x7f' => return Some(Backspace),
                '\r' => return Some(Enter),
                _ => return Some(OtherKey(ch)),
            },
            None => return None,
        }

        // --------------------------------------------------------------------
        // Match escape sequence
        // --------------------------------------------------------------------
        let mut seq = [0; 4];
        let mut seq_handle = br.take(4);
        match seq_handle.read(&mut seq) {
            Ok(_) => (),
            Err(e) => {
                if e.kind() != io::ErrorKind::UnexpectedEof {
                    let error = format!("{:?}", e);
                    self.set_status_message(&error);
                }
            }
        }
        let seq_str = String::from_utf8(seq.to_vec());

        // On error, just continue the input loop
        if seq_str.is_err() {
            return None;
        }
        let seq_str = seq_str.unwrap();

        let mut input: Vec<KeyCode<char>> = vec![];

        for ch in seq_str.chars() {
            // Since the fixed array is always filled, there
            // will be null characters. Ignore these.
            if ch == '\0' {
                continue;
            }

            input.push(match ch {
                '\x1b' => Escape,
                _ => OtherKey(ch),
            });
        }

        // Since we matched Escape earlier, if the input is empty,
        // this must be the escape key
        if input.is_empty() {
            return Some(Escape);
        }

        match input.len() {
            4 => {
                // Escape code of the form `^[[NM~`
                if input[3].eq(&OtherKey('~')) {
                    let action = match (input[1].unwrap(), input[2].unwrap()) {
                        ('1', '5') => Function('5'),
                        ('1', '7') => Function('6'),
                        ('1', '8') => Function('7'),
                        ('1', '9') => Function('8'),
                        ('2', '0') => Function('9'),
                        ('2', '1') => Function('X'), // F10
                        ('2', '4') => Function('T'), // F12
                        _ => Escape,
                    };

                    return Some(action);
                }
            }
            3 => {
                // Escape code of the form `^[[N~`
                if input[2].eq(&OtherKey('~')) {
                    let action = match input[1].unwrap() {
                        '1' => HomeKey,
                        '3' => DeleteKey,
                        '4' => EndKey,
                        '5' => PageUp,
                        '6' => PageDown,
                        '7' => HomeKey,
                        '8' => EndKey,
                        _ => Escape,
                    };

                    return Some(action);
                }
            }
            2 => {
                match input[0] {
                    // Escape code of the form `^[[X`
                    OtherKey('[') => {
                        let action = match input[1].unwrap() {
                            'A' => ArrowUp,
                            'B' => ArrowDown,
                            'C' => ArrowRight,
                            'D' => ArrowLeft,
                            'H' => HomeKey,
                            'F' => EndKey,

                            // Eh, just return escape otherwise
                            _ => Escape,
                        };

                        return Some(action);
                    }
                    // Escape code of the form `^[OX`
                    OtherKey('O') => {
                        let action = match input[1].unwrap() {
                            'H' => HomeKey,
                            'F' => EndKey,
                            'P' => Function('1'),
                            'Q' => Function('2'),
                            'R' => Function('3'),
                            'S' => Function('4'),
                            _ => Escape,
                        };

                        return Some(action);
                    }
                    _ => return Some(Escape),
                }
            }
            _ => return Some(input[0]),
        }

        // If the character doesn't match any escape sequences, just
        // pass that character on
        return Some(input[0]);
    }

    fn get_window_size(&mut self) -> TermSize {
        match get_term_size() {
            Some(size) => size,

            // I could have implemented this, but I felt that parsing
            // an escape code from stdin was of minimal value,
            // when the ioctrl method works on any computer I've tried
            None => unimplemented!("The easy way usually works"),
        }
    }

    // ------------------------------------------------------------------------
    // Syntax Highlighting
    // ------------------------------------------------------------------------

    fn update_syntax(&mut self, index: usize) {
        let rows = &mut self.rows;
        let prev_row = if index > 0 {
            // I shouldn't have to clone this, but the lifetime is
            // different than the `row` variable above, so it
            // can't be a immutable borrow. It also can't be a
            // mutable borrow, because it would be considered a
            // second mutable borrow...so a clone it is
            Some((&mut rows[index - 1]).clone())
        } else {
            None
        };
        let row = &mut rows[index];

        // Reset the highlighting of the row
        row.highlight = vec![Highlight::Normal; row.render.len()];

        if self.syntax.is_none() {
            return;
        }

        // This is dumb. This lets you get a reference to the item in
        // the option, by turning Option<T> into Option<&T>,
        // which can then be unwrapped.
        let current_syntax = self.syntax.as_ref().unwrap();

        let keywords1 = &current_syntax.keywords1;
        let keywords2 = &current_syntax.keywords2;

        let scs = &current_syntax.singleline_comment_start;
        let mcs = &current_syntax.multiline_comment_start;
        let mce = &current_syntax.multiline_comment_end;

        let mut prev_separator = true;
        let mut in_string = false;
        let mut str_start = '\0';
        let mut in_comment = prev_row.map_or(false, |row| row.highlight_comment_start);

        let mut i = 0;
        let bytes = row.render.clone().into_bytes();
        'outer: while i < row.render.len() {
            let c = bytes[i] as char;
            let prev_highlight = if i > 0 {
                row.highlight[i - 1]
            } else {
                Highlight::Normal
            };

            // Single line comments
            if scs.len() > 0 && !in_string && !in_comment {
                let range = get_slice_range(i as usize, scs.len(), row.render.len());
                if &row.render[range] == scs {
                    // Pretty simple, highlight from the match to the end of the line
                    highlight_range(
                        &mut row.highlight,
                        i as usize..row.render.len(),
                        Highlight::LineComment,
                    );
                    break;
                }
            }

            // Multi-line comments
            if mcs.len() > 0 && mce.len() > 0 && !in_string {
                let mce_slice_range = get_slice_range(i as usize, mce.len(), row.render.len());
                let mcs_slice_range = get_slice_range(i as usize, mcs.len(), row.render.len());
                if in_comment {
                    row.highlight[i as usize] = Highlight::MultiLineComment;

                    // End of a comment
                    if &row.render[mce_slice_range.clone()] == mce {
                        highlight_range(
                            &mut row.highlight,
                            mce_slice_range,
                            Highlight::MultiLineComment,
                        );

                        i += mce.len();
                        in_comment = false;
                        prev_separator = true;
                        continue;
                    } else {
                        i += 1;
                        continue;
                    }
                } else if &row.render[mcs_slice_range.clone()] == mcs {
                    // Start of a multi-line comment
                    highlight_range(
                        &mut row.highlight,
                        mcs_slice_range,
                        Highlight::MultiLineComment,
                    );

                    i += mcs.len();
                    in_comment = true;
                    continue;
                }
            }

            // Strings
            if current_syntax
                .flags
                .contains(SyntaxFlags::HIGHLIGHT_STRINGS)
            {
                if in_string {
                    row.highlight[i as usize] = Highlight::String;
                    // Don't end highlighting for a string on an escaped quote
                    if c == '\\' && i + 1 < row.render.len() {
                        row.highlight[i as usize + 1] = Highlight::String;
                        i += 2;
                        continue;
                    }

                    // End delimiter for the string
                    if c == str_start {
                        in_string = false;
                        str_start = '\0';
                    }
                    i += 1;
                    prev_separator = true;
                    continue;
                } else {
                    if (c == '"' || c == '\'') && prev_separator {
                        in_string = true;
                        str_start = c;
                        row.highlight[i as usize] = Highlight::String;
                        i += 1;
                        continue;
                    }
                }
            }

            // Numbers
            if current_syntax
                .flags
                .contains(SyntaxFlags::HIGHLIGHT_NUMBERS)
            {
                if (c.is_ascii_digit() && (prev_separator || prev_highlight == Highlight::Number))
                    || (c == '.' && prev_highlight == Highlight::Number)
                {
                    row.highlight[i as usize] = Highlight::Number;
                    i += 1;
                    prev_separator = false;
                    continue;
                }
            }

            // Keywords
            if prev_separator {
                for &keyword in keywords1 {
                    let search_range = get_slice_range(i as usize, keyword.len(), row.render.len());

                    let next_char_offset = i as usize + keyword.len() + 1;
                    let is_end_of_line = next_char_offset >= row.render.len();
                    let next_char = if is_end_of_line {
                        '\0'
                    } else {
                        bytes[next_char_offset] as char
                    };

                    if &row.render[search_range.clone()] == keyword && is_separator(next_char) {
                        highlight_range(&mut row.highlight, search_range, Highlight::Keyword1);
                        i += keyword.len();
                    }
                }

                for &keyword in keywords2 {
                    let search_range = get_slice_range(i as usize, keyword.len(), row.render.len());

                    let next_char_offset = i as usize + keyword.len() + 1;
                    let is_end_of_line = next_char_offset >= row.render.len();
                    let next_char = if is_end_of_line {
                        '\0'
                    } else {
                        bytes[next_char_offset] as char
                    };

                    if &row.render[search_range.clone()] == keyword && is_separator(next_char) {
                        highlight_range(&mut row.highlight, search_range, Highlight::Keyword2);
                        i += keyword.len();
                    }
                }
            }

            prev_separator = is_separator(c);
            i += 1;
        }

        let changed = row.highlight_comment_start != in_comment;
        row.highlight_comment_start = in_comment;

        // If a multi-line comment is opened or closed,
        // update the next row as well.
        if changed && index + 1 < self.rows.len() {
            self.update_syntax(index + 1);
        }
    }

    fn syntax_to_color(syntax_type: Highlight) -> i32 {
        use Highlight::*;

        match syntax_type {
            Keyword1 => 33,    // Yellow
            Keyword2 => 32,    // Green
            LineComment => 36, // Cyan
            MultiLineComment => 36,
            Normal => 37,
            Number => 31,      // Red
            SearchMatch => 34, // Blue
            String => 35,      // Magenta
        }
    }

    fn select_syntax_highlight(&mut self) {
        if self.filename.is_empty() {
            return;
        }

        let mut parts: Vec<&str> = self.filename.split('.').collect();

        let file_ext = String::from(".")
            + match parts.pop() {
                Some(ext) => ext,
                None => return,
            };

        let languages = &get_syntax_db();

        for language in languages {
            let file_match = language.file_match.clone();
            for ext in file_match {
                if ext == file_ext {
                    self.syntax = Some(language.clone());

                    // Re-highlight file when the type is determined
                    for x in 0..self.rows.len() {
                        self.update_syntax(x);
                    }

                    return;
                }
            }
        }
    }

    // ------------------------------------------------------------------------
    // Input
    // ------------------------------------------------------------------------

    fn prompt(
        &mut self,
        prompt: &str,
        cb: Option<&mut dyn Fn(&mut Self, &str, KeyCode<char>)>,
    ) -> String {
        let mut buffer = String::new();
        let default_cb = &mut Self::_noop_prompt_cb;

        let cb = if cb.is_some() {
            cb.unwrap()
        } else {
            default_cb
        };

        loop {
            self.set_status_message(&format!("{} {}", prompt, buffer));
            self.refresh_screen();

            let char = self.read_key();
            if char.is_some() {
                let char = char.unwrap();
                match char {
                    Backspace => {
                        buffer.pop();
                    }
                    DeleteKey => {
                        buffer.pop();
                    }
                    Escape => {
                        self.set_status_message("");
                        cb(self, &String::from(""), char);
                        return String::from("");
                    }
                    Enter => {
                        if buffer.len() != 0 {
                            self.set_status_message("");
                            cb(self, &buffer, char);
                            return buffer;
                        }
                    }
                    OtherKey(ch) => {
                        if (!ch.is_ascii_control()) && (ch as u8) < 128 {
                            buffer.push(ch);
                            // continue;
                        }
                    }
                    _ => (),
                };

                cb(self, &buffer, char);
            }
        }
    }

    fn _noop_prompt_cb(&mut self, _: &str, _: KeyCode<char>) {}

    fn move_cursor(&mut self, key: &KeyCode<char>) {
        let row = self.rows.get(self.cursor_y);
        match key {
            ArrowLeft => {
                if self.cursor_x != 0 {
                    // Move cursor left
                    self.cursor_x -= 1;
                } else if self.cursor_y > 0 {
                    // Move to the end of the previous line
                    self.cursor_y -= 1;
                    self.cursor_x = self.rows[self.cursor_y].chars.len();
                }
            }
            ArrowRight => {
                if row.is_some() && self.cursor_x < row.unwrap().chars.len() {
                    // Move cursor right
                    self.cursor_x += 1;
                } else if row.is_some() && self.cursor_x == row.unwrap().chars.len() {
                    // Move to start of next line
                    self.cursor_y += 1;
                    self.cursor_x = 0;
                }
            }
            ArrowUp => {
                if self.cursor_y > 0 {
                    self.cursor_y -= 1;
                }
            }
            ArrowDown => {
                if self.cursor_y < self.rows.len() {
                    self.cursor_y += 1;
                }
            }
            _ => (),
        };

        let row = self.rows.get(self.cursor_y);
        let row_len = if row.is_some() {
            row.unwrap().chars.len()
        } else {
            0
        };

        // Snap to end of line when scrolling down
        if self.cursor_x > row_len {
            self.cursor_x = row_len;
        }
    }

    /// Route user input to the appropriate handler method
    pub fn process_keypress(&mut self) -> Option<KeyCode<char>> {
        let key = self.read_key();
        if key.is_some() {
            let char = key.unwrap();

            match char {
                Backspace => self._del_or_backspace(Backspace),
                DeleteKey => self._del_or_backspace(DeleteKey),
                Enter => self.insert_new_line(),
                Escape => (),
                ArrowUp => self.move_cursor(&ArrowUp),
                ArrowDown => self.move_cursor(&ArrowDown),
                ArrowLeft => self.move_cursor(&ArrowLeft),
                ArrowRight => self.move_cursor(&ArrowRight),
                PageUp => self._page_up_or_down(PageUp),
                PageDown => self._page_up_or_down(PageDown),
                HomeKey => {
                    self.cursor_x = 0;
                }
                EndKey => {
                    if self.cursor_y < self.rows.len() {
                        self.cursor_x = self.rows[self.cursor_y].chars.len();
                    }
                }
                Function(_) => (),
                OtherKey(c) => {
                    if c.is_ascii_control() {
                        if c == ctrl_key('f') {
                            self.find();
                        }

                        if c == ctrl_key('q') {
                            if self.dirty > 0 && self.quit_times > 0 {
                                self.set_status_message(&format!("WARNING!!! File has unsaved changes. Press Ctrl-Q {} more times to quit.", self.quit_times));
                                self.quit_times -= 1;
                                return Some(OtherKey('\0'));
                            }
                            print!("\x1b[2J");
                            print!("\x1b[H");
                            // Break out of the input loop
                            return None;
                        }

                        if c == ctrl_key('s') {
                            // Save success/error message handled by save method
                            match self.save() {
                                Ok(_) => (),
                                Err(_) => (),
                            }
                        }

                        if c == ctrl_key('h') {
                            self._del_or_backspace(Backspace);
                        }
                    } else {
                        self.insert_char(c);
                    }
                }
            };

            self.quit_times = KILO_QUIT_TIMES;

            return key;
        }

        // Continue the main input loop
        Some(OtherKey('\0'))
    }

    fn _del_or_backspace(&mut self, key: KeyCode<char>) {
        if key == DeleteKey {
            self.move_cursor(&ArrowRight);
        }
        self.delete_char();
    }

    fn _page_up_or_down(&mut self, key: KeyCode<char>) {
        let mut times = self.screen_rows;

        // Update the cursor position
        match key {
            PageUp => {
                self.cursor_y = self.row_offset;
            }
            PageDown => {
                self.cursor_y = self.row_offset + self.screen_rows - 1;
                if self.cursor_y > self.rows.len() {
                    self.cursor_y = self.rows.len();
                }
            }
            _ => (),
        }

        // Scroll the file up or down
        while times > 1 {
            times -= 1;
            self.move_cursor(match key {
                PageUp => &ArrowUp,
                PageDown => &ArrowDown,
                _ => &OtherKey('\0'),
            })
        }
    }

    // ------------------------------------------------------------------------
    // Output
    // ------------------------------------------------------------------------

    /// Equivalent of the abAppend function
    /// in the original tutorial, just appends
    /// to the `output_buffer` String in the
    /// editor struct.
    fn append_out(&mut self, str: &str) {
        self.output_buffer.push_str(str);
    }

    fn append_out_char(&mut self, ch: char) {
        self.output_buffer.push(ch);
    }

    fn scroll(&mut self) {
        self.render_x = 0;
        if self.cursor_y < self.rows.len() {
            self.render_x = self.row_cx_to_rx(self.cursor_y, self.cursor_x);
        }

        // Vertical scrolling
        if self.cursor_y < self.row_offset {
            self.row_offset = self.cursor_y;
        }
        if self.cursor_y >= self.row_offset + self.screen_rows {
            self.row_offset = self.cursor_y - self.screen_rows + 1;
        }

        // Horizontal scrolling
        if self.render_x < self.col_offset {
            self.col_offset = self.render_x;
        }
        if self.render_x >= self.col_offset + self.screen_cols {
            self.col_offset = self.render_x - self.screen_cols + 1;
        }
    }

    fn draw_rows(&mut self) {
        for y in 0..self.screen_rows {
            let file_row = y + self.row_offset;
            if file_row >= self.rows.len() {
                if self.rows.is_empty() && y == (self.screen_rows / 3) {
                    let mut welcome = format!(
                        "Oxidized Kilo editor -- version {}",
                        env!("CARGO_PKG_VERSION")
                    );
                    if welcome.len() > self.screen_cols {
                        welcome.truncate(self.screen_cols)
                    }

                    // Center welcome message
                    let mut padding = (self.screen_cols - welcome.len()) / 2;
                    if padding > 0 {
                        self.append_out_char('~');
                        padding -= 1;
                    }
                    for _ in 0..padding {
                        self.append_out_char(' ');
                    }

                    self.append_out(&welcome);
                } else {
                    self.append_out_char('~');
                }
            } else {
                let output = self.rows[file_row].render.clone();
                let mut current_color: i32 = -1;

                for (x, ch) in output.char_indices() {
                    if ch.is_ascii_control() {
                        // Display unprintable characters in inverted colors
                        let sym = if ch as u8 <= 26 {
                            ('@' as u8 + ch as u8) as char
                        } else {
                            '?'
                        };

                        self.append_out("\x1b[7m");
                        self.append_out_char(sym);
                        self.append_out("\x1b[m");
                        if current_color != -1 {
                            let code = format!("\x1b[{}m", current_color);
                            self.append_out(&code);
                        }
                    } else if self.rows[file_row].highlight[x] == Highlight::Normal {
                        if current_color != -1 {
                            self.append_out("\x1b[39m");
                            current_color = -1;
                        }
                        self.append_out_char(ch);
                    } else {
                        let color = Self::syntax_to_color(self.rows[file_row].highlight[x]);
                        if color != current_color {
                            current_color = color;
                            let code = format!("\x1b[{}m", color);
                            self.append_out(&code);
                        }
                        self.append_out_char(ch);
                    }
                }
                self.append_out("\x1b[39m");
            }

            self.append_out("\x1b[K");
            self.append_out("\r\n");
        }
    }

    fn draw_status_bar(&mut self) {
        self.append_out("\x1b[7m");

        let filename = if self.filename.is_empty() {
            "[No Name]"
        } else {
            &self.filename
        };

        let modified = if self.dirty > 0 { "(modified}" } else { "" };

        let mut left_message = format!("{:.80} - {} lines {}", filename, self.rows.len(), modified);
        let file_type = match &self.syntax {
            Some(s) => &s.file_type,
            None => "no ft",
        };
        let right_message = format!("{} | {}/{}", file_type, self.cursor_y + 1, self.rows.len());
        let mut len = left_message.len();
        if len > self.screen_cols {
            len = self.screen_cols;
            left_message.truncate(len);
        }
        self.append_out(&left_message);

        for x in len..self.screen_cols {
            if self.screen_cols - x == right_message.len() {
                self.append_out(&right_message);
                break;
            }
            self.append_out(" ");
        }
        self.append_out("\x1b[m");
        self.append_out("\r\n");
    }

    fn draw_message_bar(&mut self) {
        self.append_out("\x1b[K");

        let mut message = self.status_message.clone();
        let message_len = message.len();
        if message_len > self.screen_cols {
            message.truncate(self.screen_cols);
        }

        let five_seconds = Duration::from_secs(5);
        if message_len > 0 && self.status_message_time.elapsed() < five_seconds {
            self.append_out(&message);
        }
    }

    pub fn refresh_screen(&mut self) {
        self.scroll();
        self.output_buffer.clear();

        //  Hide cursor, reposition cursor
        self.append_out("\x1b[?25l");
        self.append_out("\x1b[H");

        self.draw_rows();
        self.draw_status_bar();
        self.draw_message_bar();

        // Move cursor to state position
        let y = self.cursor_y - self.row_offset + 1;
        let x = self.render_x - self.col_offset + 1;
        let cursor_code = format!("\x1b[{y};{x}H", y = y, x = x);
        self.append_out(&cursor_code);

        // Show cursor
        self.append_out("\x1b[?25h");

        let stdout = io::stdout();
        let mut handle = stdout.lock();

        // If you can't write to stdout, you might as well just panic
        handle.write_all(&self.output_buffer.as_bytes()).unwrap();
    }

    /// Set the status bar message
    ///
    /// To avoid creating a macro that would just forward to
    /// the `format!` macro, this method only accepts a pre-formatted
    /// string.
    ///
    /// # Example
    ///
    /// ```no-run
    /// # use rs-kilo::editor::Editor;
    /// # let editor = Editor::new();
    /// let message = format!("{} is {}", key, status);
    /// editor.set_status_message(&message);
    /// ```
    pub fn set_status_message(&mut self, message: &str) {
        self.status_message = message.to_owned();
        self.status_message_time = Instant::now();
    }

    // ------------------------------------------------------------------------
    // Row Operations
    // ------------------------------------------------------------------------

    fn row_cx_to_rx(&mut self, index: usize, cx: usize) -> usize {
        let mut rx: usize = 0;
        let mut i: usize = 0;

        for char in self.rows[index].chars.chars() {
            if char == '\t' {
                rx += (KILO_TAB_STOP - 1) - (rx % KILO_TAB_STOP);
            } else {
                rx += 1;
            }

            if i > cx {
                return rx;
            }

            i += 1;
        }

        rx
    }

    fn row_rx_to_cx(&mut self, index: usize, rx: usize) -> usize {
        let mut current_rx: usize = 0;
        let mut cx: usize = 0;

        for char in self.rows[index].chars.chars() {
            if char == '\t' {
                current_rx += (KILO_TAB_STOP - 1) - (current_rx % KILO_TAB_STOP);
            } else {
                current_rx += 1;
            }

            if current_rx > rx {
                return cx;
            }

            cx += 1;
        }

        cx
    }

    /// Convert file characters to their display equivalents
    fn update_row(&mut self, index: usize) {
        let row = &mut self.rows[index];
        let str = row.chars.clone();

        // Cheat at rendering tabs as spaces
        let str = str.replace('\t', "    ");
        row.render = str;

        // Syntax highlighting
        self.update_syntax(index);
    }

    fn insert_row(&mut self, at: usize, content: &str) {
        if at > self.rows.len() {
            return;
        }

        let row = Row::new(content);

        self.rows.insert(at, row);
        self.update_row(at);

        self.dirty += 1;
    }

    fn delete_row(&mut self, row_index: usize) {
        if row_index > self.rows.len() {
            return;
        }

        self.rows.remove(row_index);

        self.dirty += 1;
    }

    fn row_insert_char(&mut self, row_index: usize, char_index: usize, ch: char) {
        let mut at = char_index;
        let row = &mut self.rows[row_index];

        if at > row.chars.len() {
            at = row.chars.len();
        }

        row.chars.insert(at, ch);

        self.update_row(row_index);

        self.dirty += 1;
    }

    fn row_append_string(&mut self, row_index: usize, strng: &str) {
        let row = &mut self.rows[row_index];
        row.chars += strng;

        self.update_row(row_index);

        self.dirty += 1;
    }

    fn row_delete_char(&mut self, row_index: usize, char_index: usize) {
        let row = &mut self.rows[row_index];
        if char_index >= row.chars.len() {
            return;
        }

        row.chars.remove(char_index);
        self.update_row(row_index);

        self.dirty += 1;
    }

    // ------------------------------------------------------------------------
    // Editor Operations
    // ------------------------------------------------------------------------

    fn insert_char(&mut self, ch: char) {
        if self.cursor_y == self.rows.len() {
            self.insert_row(self.rows.len(), "");
        }

        self.row_insert_char(self.cursor_y, self.cursor_x, ch);
        self.cursor_x += 1;
    }

    fn insert_new_line(&mut self) {
        if self.cursor_x == 0 {
            self.insert_row(self.cursor_y, "");
        } else {
            // Clone the contents of the current row
            let row = &mut self.rows[self.cursor_y];
            let row_chars = row.chars.clone();

            // Truncate the original row up to the cursor
            row.chars.truncate(self.cursor_x);

            // Create the new row as a slice of the contents of the old
            // row, from the cursor to the end of the line
            let slice = &row_chars[self.cursor_x..];
            self.insert_row(self.cursor_y + 1, slice);

            self.update_row(self.cursor_y);
        }

        self.cursor_y += 1;
        self.cursor_x = 0;
    }

    fn delete_char(&mut self) {
        if self.cursor_y == self.rows.len() {
            return;
        }

        if self.cursor_x == 0 && self.cursor_y == 0 {
            return;
        }

        if self.cursor_x > 0 {
            self.row_delete_char(self.cursor_y, self.cursor_x - 1);
            self.cursor_x -= 1;
        } else {
            // When deleting the first character in the row, collapse that row into the previous one
            self.cursor_x = self.rows[self.cursor_y - 1].chars.len();
            self.row_append_string(self.cursor_y - 1, &self.rows[self.cursor_y].chars.clone());
            self.delete_row(self.cursor_y);

            self.cursor_y -= 1;
        }
    }

    // ------------------------------------------------------------------------
    // File I/O
    // ------------------------------------------------------------------------

    fn rows_to_string(&mut self) -> String {
        let mut output = String::new();

        for row in &self.rows {
            // When the file is opened, newlines are stripped
            // make sure to add them back when saving!
            output += &row.chars;
            output.push('\n');
        }

        output
    }

    /// Open a file for display
    pub fn open(&mut self, filename: &str) -> io::Result<()> {
        self.filename = filename.to_owned();

        self.select_syntax_highlight();

        let file = File::open(&self.filename)?;
        let buf_reader = BufReader::new(file);

        let lines = buf_reader.lines().map(|l| clean_unwrap(l));

        for line in lines {
            self.insert_row(self.rows.len(), &line);
        }

        self.dirty = 0;

        Ok(())
    }

    fn save(&mut self) -> io::Result<()> {
        if self.filename.len() == 0 {
            self.filename = self.prompt("Save as (ESC to cancel):", None);
            if self.filename.len() == 0 {
                self.set_status_message("Save aborted");
                return Ok(());
            }

            self.select_syntax_highlight();
        }

        let mut file = File::create(&self.filename)?;
        let data = &mut self.rows_to_string();

        let res = file.write_all(data.as_bytes());

        match res {
            Ok(()) => {
                self.dirty = 0;

                self.set_status_message(&format!("{} bytes written to disk", data.len()));
            }
            Err(e) => self.set_status_message(&format!("Failed to save: {:?}", e)),
        };

        file.sync_all()?;

        Ok(())
    }

    // ------------------------------------------------------------------------
    // Find
    // ------------------------------------------------------------------------

    fn find_callback(&mut self, query: &str, key: KeyCode<char>) {
        if !self.search_last_hightlight.is_empty() {
            self.rows[self.search_last_line].highlight = self.search_last_hightlight.clone();
            self.search_last_hightlight.clear();
        }

        if key == Enter || key == Escape {
            self.search_last_match = -1;
            self.search_direction = 1;
            return;
        } else if key == ArrowRight || key == ArrowDown {
            self.search_direction = 1;
        } else if key == ArrowLeft || key == ArrowUp {
            self.search_direction = -1;
        } else {
            self.search_last_match = -1;
            self.search_direction = 1;
        }

        if self.search_last_match == -1 {
            self.search_direction = 1;
        }

        if query.is_empty() {
            return;
        }

        let mut current = self.search_last_match;
        for x in 0..self.rows.len() {
            current += self.search_direction as i32;

            if current == -1 {
                current = self.rows.len() as i32 - 1;
            } else if current == self.rows.len() as i32 {
                current = 0;
            }

            match self.rows[current as usize].render.find(query) {
                None => (),
                Some(start) => {
                    self.search_last_match = current;
                    self.cursor_y = current as usize;
                    self.cursor_x = self.row_rx_to_cx(x, start);
                    self.row_offset = self.rows.len();

                    self.search_last_line = current as usize;
                    self.search_last_hightlight = self.rows[current as usize].highlight.clone();

                    // Highlight matching search result
                    let len = start + query.len();
                    highlight_range(
                        &mut self.rows[current as usize].highlight,
                        start..len,
                        Highlight::SearchMatch,
                    );

                    break;
                }
            }
        }
    }

    fn find(&mut self) {
        let saved_cx = self.cursor_x;
        let saved_cy = self.cursor_y;
        let saved_coloff = self.col_offset;
        let saved_rowoff = self.row_offset;

        let query = self.prompt(
            "Search (Use ESC/Arrows/Enter):",
            Some(&mut Self::find_callback),
        );

        if query.is_empty() {
            self.cursor_x = saved_cx;
            self.cursor_y = saved_cy;
            self.col_offset = saved_coloff;
            self.row_offset = saved_rowoff;
        }
    }
}

// ------------------------------------------------------------------------
// Functions
// ------------------------------------------------------------------------

/// Get the language highlighting config
fn get_syntax_db() -> Vec<Syntax> {
    vec![
        Syntax::new(
            "c",
            vec![".c", ".h", ".cpp"],
            vec![
                "continue", "typedef", "switch", "return", "static", "while", "break", "struct",
                "union", "class", "else", "enum", "for", "case", "if",
            ],
            vec![
                "#include", "unsigned", "#define", "#ifndef", "double", "signed", "#endif",
                "#ifdef", "float", "#error", "#undef", "long", "char", "int", "void", "#if",
            ],
            "//",
            "/*",
            "*/",
            SyntaxFlags::HIGHLIGHT_NUMBERS | SyntaxFlags::HIGHLIGHT_STRINGS,
        ),
        Syntax::new(
            "rust",
            vec![".rs"],
            vec![
                "continue", "return", "static", "struct", "unsafe", "break", "const", "crate",
                "extern", "match", "super", "trait", "where", "else", "enum", "false", "impl",
                "loop", "move", "self", "type", "while", "for", "let", "mod", "pub", "ref", "true",
                "use", "mut", "as", "fn", "if", "in",
            ],
            vec![
                "DoubleEndedIterator",
                "ExactSizeIterator",
                "IntoIterator",
                "PartialOrd",
                "PartialEq",
                "Iterator",
                "ToString",
                "Default",
                "ToOwned",
                "Extend",
                "FnOnce",
                "Option",
                "String",
                "AsMut",
                "AsRef",
                "Clone",
                "Debug",
                "FnMut",
                "Sized",
                "Unpin",
                "array",
                "isize",
                "usize",
                "&str",
                "Copy",
                "Drop",
                "From",
                "Into",
                "None",
                "Self",
                "Send",
                "Some",
                "Sync",
                "Sync",
                "bool",
                "char",
                "i128",
                "u128",
                "Box",
                "Err",
                "Ord",
                "Vec",
                "dyn",
                "f32",
                "f64",
                "i16",
                "i32",
                "i64",
                "str",
                "u16",
                "u32",
                "u64",
                "Eq",
                "Fn",
                "Ok",
                "i8",
                "u8",
            ],
            "//",
            "/*",
            "*/",
            SyntaxFlags::HIGHLIGHT_NUMBERS | SyntaxFlags::HIGHLIGHT_STRINGS,
        ),
    ]
}

/// Convert Ctrl+letter chords to their
/// ASCII table equivalents
pub fn ctrl_key(c: char) -> char {
    let key = c as u8;

    if !c.is_ascii() {
        panic!("CTRL_KEY only accepts ASCII characters");
    }

    // Intentionally "overflow" u8 to wrap around to the
    // beginning of the ASCII table. Ctrl+a is 1, Ctrl+b is 2, etc.
    (key & 0x1f) as char
}

/// Determine whether a character is one which separates tokens
/// in the language to highlight
fn is_separator(input_char: char) -> bool {
    if input_char.is_ascii_whitespace() || input_char == '\0' {
        return true;
    }

    let separator_chars = ",.()+-/*=~%<>[];";

    for ch in separator_chars.chars() {
        if input_char == ch {
            return true;
        }
    }

    false
}

/// Get a range for a slice of a string or vector, checking the length of the
/// string or vector to prevent panics on invalid access.
///
/// If `start` to `start + search_len`, is within the size of the search target (`haystack_len`)
/// that range is returned. Otherwise, the range is from `start` to `haystack_len`.
fn get_slice_range(start: usize, needle_len: usize, haystack_len: usize) -> Range<usize> {
    let search_len = start + needle_len;
    if search_len >= haystack_len {
        start..haystack_len
    } else {
        start..search_len
    }
}

/// Set the highlighting type for the specified range
/// Kind of similar to the C memset calls
fn highlight_range(vec: &mut Vec<Highlight>, range: Range<usize>, value: Highlight) {
    for x in range {
        vec[x] = value;
    }
}

/// Do the equivalent of a Result::unwrap, but cleanup terminal output
/// first, so it doesn't destroy console output afterwards.
fn clean_unwrap<O, E>(res: Result<O, E>) -> O
where
    E: std::fmt::Debug,
{
    match res {
        Ok(value) => value,
        Err(e) => {
            disable_raw_mode();
            println!("\r\n");
            panic!("{:?}", e);
        }
    }
}

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

    #[test]
    fn select_syntax_highlight_selects_language() {
        let langs = get_syntax_db();
        let mut editor = Editor::new();
        editor.filename = String::from("foo.c");

        editor.select_syntax_highlight();

        assert_eq!(editor.syntax.as_ref(), Some(&langs[0]));
    }

    #[test]
    fn is_separator_works() {
        assert_eq!(is_separator(' '), true);
        assert_eq!(is_separator('_'), false);
    }
}