//! This module implements and describes common TTY methods & traits
use std::io::{self, Write};
use unicode_segmentation::UnicodeSegmentation;
use unicode_width::UnicodeWidthStr;

use config::{ColorMode, Config};
use consts::KeyPress;
use line_buffer::LineBuffer;
use Result;

/// Terminal state
pub trait RawMode: Sized {
    /// Disable RAW mode for the terminal.
    fn disable_raw_mode(&self) -> Result<()>;
}

/// Translate bytes read from stdin to keys.
pub trait RawReader {
    /// Blocking read of key pressed.
    fn next_key(&mut self, single_esc_abort: bool) -> Result<KeyPress>;
    /// For CTRL-V support
    #[cfg(unix)]
    fn next_char(&mut self) -> Result<char>;
}

#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
pub struct Position {
    pub col: usize,
    pub row: usize,
}

/// Display prompt, line and cursor in terminal output
pub trait Renderer {
    fn move_cursor(&mut self, old: Position, new: Position) -> Result<()>;

    /// Display prompt, line and cursor in terminal output
    fn refresh_line(
        &mut self,
        prompt: &str,
        prompt_size: Position,
        line: &LineBuffer,
        hint: Option<String>,
        current_row: usize,
        old_rows: usize,
    ) -> Result<(Position, Position)>;

    /// Calculate the number of columns and rows used to display `s` on a
    /// `cols` width terminal
    /// starting at `orig`.
    fn calculate_position(&self, s: &str, orig: Position) -> Position;

    fn write_and_flush(&mut self, buf: &[u8]) -> Result<()>;

    /// Beep, used for completion when there is nothing to complete or when all
    /// the choices were already shown.
    fn beep(&mut self) -> Result<()> {
        // TODO bell-style
        try!(io::stderr().write_all(b"\x07"));
        try!(io::stderr().flush());
        Ok(())
    }

    /// Clear the screen. Used to handle ctrl+l
    fn clear_screen(&mut self) -> Result<()>;

    /// Check if a SIGWINCH signal has been received
    fn sigwinch(&self) -> bool;
    /// Update the number of columns/rows in the current terminal.
    fn update_size(&mut self);
    /// Get the number of columns in the current terminal.
    fn get_columns(&self) -> usize;
    /// Get the number of rows in the current terminal.
    fn get_rows(&self) -> usize;
}

impl<'a, R: Renderer + ?Sized> Renderer for &'a mut R {
    fn move_cursor(&mut self, old: Position, new: Position) -> Result<()> {
        (**self).move_cursor(old, new)
    }
    fn refresh_line(
        &mut self,
        prompt: &str,
        prompt_size: Position,
        line: &LineBuffer,
        hint: Option<String>,
        current_row: usize,
        old_rows: usize,
    ) -> Result<(Position, Position)> {
        (**self).refresh_line(prompt, prompt_size, line, hint, current_row, old_rows)
    }
    fn calculate_position(&self, s: &str, orig: Position) -> Position {
        (**self).calculate_position(s, orig)
    }
    fn write_and_flush(&mut self, buf: &[u8]) -> Result<()> {
        (**self).write_and_flush(buf)
    }
    fn beep(&mut self) -> Result<()> {
        (**self).beep()
    }
    fn clear_screen(&mut self) -> Result<()> {
        (**self).clear_screen()
    }
    fn sigwinch(&self) -> bool {
        (**self).sigwinch()
    }
    fn update_size(&mut self) {
        (**self).update_size()
    }
    fn get_columns(&self) -> usize {
        (**self).get_columns()
    }
    fn get_rows(&self) -> usize {
        (**self).get_rows()
    }
}

/// Terminal contract
pub trait Term {
    type Reader: RawReader; // rl_instream
    type Writer: Renderer; // rl_outstream
    type Mode: RawMode;

    fn new(color_mode: ColorMode) -> Self;
    /// Check if current terminal can provide a rich line-editing user
    /// interface.
    fn is_unsupported(&self) -> bool;
    /// check if stdin is connected to a terminal.
    fn is_stdin_tty(&self) -> bool;
    /// Check if output supports colors.
    fn colors_enabled(&self) -> bool;
    /// Enable RAW mode for the terminal.
    fn enable_raw_mode(&mut self) -> Result<Self::Mode>;
    /// Create a RAW reader
    fn create_reader(&self, config: &Config) -> Result<Self::Reader>;
    /// Create a writer
    fn create_writer(&self) -> Self::Writer;
}

fn truncate(text: &str, col: usize, max_col: usize) -> &str {
    let mut col = col;
    let mut esc_seq = 0;
    let mut end = text.len();
    for (i, s) in text.grapheme_indices(true) {
        col += width(s, &mut esc_seq);
        if col > max_col {
            end = i;
            break;
        }
    }
    &text[..end]
}

fn width(s: &str, esc_seq: &mut u8) -> usize {
    if *esc_seq == 1 {
        if s == "[" {
            // CSI
            *esc_seq = 2;
        } else {
            // two-character sequence
            *esc_seq = 0;
        }
        0
    } else if *esc_seq == 2 {
        if s == ";" || (s.as_bytes()[0] >= b'0' && s.as_bytes()[0] <= b'9') {
        /*} else if s == "m" {
            // last
            *esc_seq = 0;*/
        } else {
            // not supported
            *esc_seq = 0;
        }
        0
    } else if s == "\x1b" {
        *esc_seq = 1;
        0
    } else if s == "\n" {
        0
    } else {
        s.width()
    }
}

// If on Windows platform import Windows TTY module
// and re-export into mod.rs scope
#[cfg(all(windows, not(test)))]
mod windows;
#[cfg(all(windows, not(test)))]
pub use self::windows::*;

// If on Unix platform import Unix TTY module
// and re-export into mod.rs scope
#[cfg(all(unix, not(test)))]
mod unix;
#[cfg(all(unix, not(test)))]
pub use self::unix::*;

#[cfg(test)]
mod test;
#[cfg(test)]
pub use self::test::*;