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//! # cansi
//! 
//! [![Build Status](https://travis-ci.com/kurtlawrence/cansi.svg?branch=master)](https://travis-ci.com/kurtlawrence/cansi)
//! [![Latest Version](https://img.shields.io/crates/v/cansi.svg)](https://crates.io/crates/cansi)
//! [![Rust Documentation](https://img.shields.io/badge/api-rustdoc-blue.svg)](https://docs.rs/cansi)
//! [![codecov](https://codecov.io/gh/kurtlawrence/cansi/branch/master/graph/badge.svg)](https://codecov.io/gh/kurtlawrence/cansi)
//! 
//! ## **C**atergorise **ANSI** - ANSI escape code parser and categoriser
//! 
//! See the [rs docs.](https://docs.rs/cansi/)
//! Look at progress and contribute on [github.](https://github.com/kurtlawrence/cansi)
//! 
//! `cansi` will parse text with ANSI escape sequences in it and return a deconstructed text with metadata around the colouring and styling. `cansi` is only concerned with `CSI` sequences, particuarly the `SGR` parameters. `cansi` will not construct escaped text, there are crates such as [`colored`](https://crates.io/crates/colored) that do a great job of colouring and styling text.
//! 
//! ## Example usage
//! 
//! > This example was done using the `colored` crate to help with constructing the escaped text string. It will work with other tools that inject escape sequences into text strings (given they follow [ANSI specification](https://en.wikipedia.org/wiki/ANSI_escape_code)).
//! 
//! ```rust
//! extern crate cansi;
//! extern crate colored;
//! 
//! use cansi::*;
//! use colored::*;
//! use std::io::Write;
//! 
//! let v = &mut Vec::new();
//! write!(
//!   v,
//!   "Hello, {}{}{}{}{}{}",
//!   "w".white().on_red(),
//!   "o".cyan().on_green(),
//!   "r".magenta().on_yellow(),
//!   "l".blue().on_white(),
//!   "d".yellow().on_bright_cyan(),
//!   "!".bright_red().on_bright_yellow(),
//! )
//! .unwrap();
//! 
//! let text = String::from_utf8_lossy(&v);
//! let result = categorise_text(&text); // cansi function
//! 
//! assert_eq!(result.len(), 7); // there should be seven differently styled components
//! 
//! assert_eq!("Hello, world!", &construct_text_no_codes(&result));
//! 
//! // 'Hello, ' is just defaults
//! assert_eq!(
//!   result[0],
//!   CategorisedSlice {
//!     text_as_bytes: b"Hello, ",
//!     fg_colour: Color::White,
//!     bg_colour: Color::Black,
//!     intensity: Intensity::Normal,
//!     italic: false,
//!     underline: false,
//!     blink: false,
//!     reversed: false,
//!     hidden: false,
//!     strikethrough: false
//!   }
//! );
//! 
//! // 'w' is coloured differently
//! assert_eq!(
//!   result[1],
//!   CategorisedSlice {
//!     text_as_bytes: b"w",
//!     fg_colour: Color::White,
//!     bg_colour: Color::Red,
//!     intensity: Intensity::Normal,
//!     italic: false,
//!     underline: false,
//!     blink: false,
//!     reversed: false,
//!     hidden: false,
//!     strikethrough: false
//!   }
//! );
//! ```

#![warn(missing_docs)]

extern crate colored;
extern crate parse_ansi;

#[cfg(test)]
mod tests;

/// Re-export of [colored::Color](https://docs.rs/colored/1.6.1/colored/enum.Color.html).
pub use self::colored::Color;

const SEPARATOR: u8 = b';';

/// Type definition of the collection of `CategorisedSlice`s.
pub type CategorisedSlices<'text> = Vec<CategorisedSlice<'text>>;

/// Constructs a string of the categorised text without the ANSI escape characters.
///
/// # Example
/// ```rust
/// use cansi::*;
/// let categorised = categorise_text("\x1b[30mH\x1b[31me\x1b[32ml\x1b[33ml\x1b[34mo");
/// assert_eq!("Hello", &construct_text_no_codes(&categorised));
/// ```
pub fn construct_text_no_codes(categorised_slices: &CategorisedSlices) -> String {
    String::from_utf8_lossy(
        &categorised_slices
            .iter()
            .flat_map(|r| r.text_as_bytes)
            .map(|x| *x)
            .collect::<Vec<_>>()[..],
    )
    .into_owned()
}

/// Parses the text and returns each formatted slice in order.
/// The ANSI escape codes are not included in the text slices.
///
/// Each different text slice is returned in order such that the text without the escape characters can be reconstructed.
/// There is a helper function (`construct_text_no_codes`) on `CategorisedSlices` for this.
pub fn categorise_text(text: &str) -> CategorisedSlices {
    let mut sgr = SGR::default();
    let mut lo = 0;
    let mut slices: Vec<CategorisedSlice> = Vec::new();
    let text = text.as_bytes();
    for m in parse_ansi::parse_bytes(text) {
        // add in the text before CSI with the previous SGR format
        let hi = m.start();
        if hi != lo {
            slices.push(CategorisedSlice {
                text_as_bytes: &text[lo..hi],
                fg_colour: sgr.fg_colour,
                bg_colour: sgr.bg_colour,
                intensity: sgr.intensity.clone(),
                italic: sgr.italic,
                underline: sgr.underline,
                blink: sgr.blink,
                reversed: sgr.reversed,
                hidden: sgr.hidden,
                strikethrough: sgr.strikethrough,
            });
        }

        lo = m.end();
        let mut escape_seq = m.as_bytes().iter().skip(2); // skip the first two (would be ESC *)
        sgr = SGR::default();
        let mut seq = Vec::new();
        // spec at https://en.wikipedia.org/wiki/ANSI_escape_code#Escape_sequences
        while let Some(byte) = escape_seq.next() {
            if byte == &SEPARATOR || (byte >= &b'\x40' && byte <= &b'\x7e') {
                // signals the end of a sequence, need to process what was transferred
                // if seq is empty, this is treated as a default flag
                if seq.len() == 0 {
                    sgr = SGR::default();
                } else {
                    // this map is a bit weird but i didn't want to have to convert to characters just
                    // to make this mapping more simple. so the seq is in bytes and has to map back to utf8
                    // 0-9 characters (effectively 48-57 in decimal notation)
                    match &seq[..] {
                        &[48] => sgr = SGR::default(),                         // 0
                        &[49] => sgr.intensity = Intensity::Bold,              // 1
                        &[50] => sgr.intensity = Intensity::Faint,             // 2
                        &[51] => sgr.italic = true,                            // 3
                        &[52] => sgr.underline = true,                         // 4
                        &[53] => sgr.blink = true,                             // 5
                        &[55] => sgr.reversed = true,                          // 7
                        &[56] => sgr.hidden = true,                            // 8
                        &[57] => sgr.strikethrough = true,                     // 9
                        &[50, 50] => sgr.intensity = Intensity::Normal,        // 22
                        &[50, 51] => sgr.italic = false,                       // 23
                        &[50, 52] => sgr.underline = false,                    // 24
                        &[50, 53] => sgr.blink = false,                        // 25
                        &[50, 55] => sgr.reversed = false,                     // 27
                        &[50, 56] => sgr.hidden = false,                       // 28
                        &[50, 57] => sgr.strikethrough = false,                // 29
                        &[51, 48] => sgr.fg_colour = Color::Black,             // 30
                        &[51, 49] => sgr.fg_colour = Color::Red,               // 31
                        &[51, 50] => sgr.fg_colour = Color::Green,             // 32
                        &[51, 51] => sgr.fg_colour = Color::Yellow,            // 33
                        &[51, 52] => sgr.fg_colour = Color::Blue,              // 34
                        &[51, 53] => sgr.fg_colour = Color::Magenta,           // 35
                        &[51, 54] => sgr.fg_colour = Color::Cyan,              // 36
                        &[51, 55] => sgr.fg_colour = Color::White,             // 37
                        &[52, 48] => sgr.bg_colour = Color::Black,             // 40
                        &[52, 49] => sgr.bg_colour = Color::Red,               // 41
                        &[52, 50] => sgr.bg_colour = Color::Green,             // 42
                        &[52, 51] => sgr.bg_colour = Color::Yellow,            // 43
                        &[52, 52] => sgr.bg_colour = Color::Blue,              // 44
                        &[52, 53] => sgr.bg_colour = Color::Magenta,           // 45
                        &[52, 54] => sgr.bg_colour = Color::Cyan,              // 46
                        &[52, 55] => sgr.bg_colour = Color::White,             // 47
                        &[57, 48] => sgr.fg_colour = Color::BrightBlack,       // 90
                        &[57, 49] => sgr.fg_colour = Color::BrightRed,         // 91
                        &[57, 50] => sgr.fg_colour = Color::BrightGreen,       // 92
                        &[57, 51] => sgr.fg_colour = Color::BrightYellow,      // 93
                        &[57, 52] => sgr.fg_colour = Color::BrightBlue,        // 94
                        &[57, 53] => sgr.fg_colour = Color::BrightMagenta,     // 95
                        &[57, 54] => sgr.fg_colour = Color::BrightCyan,        // 96
                        &[57, 55] => sgr.fg_colour = Color::BrightWhite,       // 97
                        &[49, 48, 48] => sgr.bg_colour = Color::BrightBlack,   // 100
                        &[49, 48, 49] => sgr.bg_colour = Color::BrightRed,     // 101
                        &[49, 48, 50] => sgr.bg_colour = Color::BrightGreen,   // 102
                        &[49, 48, 51] => sgr.bg_colour = Color::BrightYellow,  // 103
                        &[49, 48, 52] => sgr.bg_colour = Color::BrightBlue,    // 104
                        &[49, 48, 53] => sgr.bg_colour = Color::BrightMagenta, // 105
                        &[49, 48, 54] => sgr.bg_colour = Color::BrightCyan,    // 106
                        &[49, 48, 55] => sgr.bg_colour = Color::BrightWhite,   // 107
                        _ => (),
                    }
                }
                seq.clear();
            } else {
                seq.push(*byte); // not a signal to process so just push onto seq
            }
        }
    }

    if lo != text.len() {
        slices.push(CategorisedSlice {
            text_as_bytes: &text[lo..text.len()],
            fg_colour: sgr.fg_colour,
            bg_colour: sgr.bg_colour,
            intensity: sgr.intensity.clone(),
            italic: sgr.italic,
            underline: sgr.underline,
            blink: sgr.blink,
            reversed: sgr.reversed,
            hidden: sgr.hidden,
            strikethrough: sgr.strikethrough,
        });
    }

    slices
}

/// Construct an iterator over each new line (`\n` or `\r\n`) and returns the categorised slices within those.
/// `CategorisedSlice`s that include a new line are split with the same style.
///
/// # Example
/// ```rust
/// use colored::*;
/// use cansi::*;
///
/// let s = format!("{}{}\nhow are you\r\ntoday", "hello, ".green(), "world".red());
/// let cat = categorise_text(&s);
/// let mut iter = line_iter(&cat);
///
/// let first = iter.next().unwrap();
/// assert_eq!(first[0].text_as_bytes, b"hello, ");
/// assert_eq!(first[0].fg_colour, Color::Green);
///
/// assert_eq!(first[1].text_as_bytes, b"world");
/// assert_eq!(first[1].fg_colour, Color::Red);
///
/// assert_eq!(&construct_text_no_codes(&iter.next().unwrap()), "how are you");
/// assert_eq!(&construct_text_no_codes(&iter.next().unwrap()), "today");
/// assert_eq!(iter.next(), None);
/// ```
pub fn line_iter<'text, 'iter>(
    categorised_slices: &'iter CategorisedSlices<'text>,
) -> CategorisedLineIterator<'text, 'iter> {
    CategorisedLineIterator {
        slices: categorised_slices,
        idx: 0,
        prev: None,
    }
}

/// An iterator structure for `CategorisedSlices`, iterating over each new line (`\n` or `\r\n`) and returns the categorised slices within those.
/// `CategorisedSlice`s that include a new line are split with the same style.
///
/// # Example
/// ```rust
/// use colored::*;
/// use cansi::*;
///
/// let s = format!("{}{}\nhow are you\r\ntoday", "hello, ".green(), "world".red());
/// let cat = categorise_text(&s);
/// let mut iter = line_iter(&cat);
///
/// let first = iter.next().unwrap();
/// assert_eq!(first[0].text_as_bytes, b"hello, ");
/// assert_eq!(first[0].fg_colour, Color::Green);
///
/// assert_eq!(first[1].text_as_bytes, b"world");
/// assert_eq!(first[1].fg_colour, Color::Red);
///
/// assert_eq!(&construct_text_no_codes(&iter.next().unwrap()), "how are you");
/// assert_eq!(&construct_text_no_codes(&iter.next().unwrap()), "today");
/// assert_eq!(iter.next(), None);
/// ```
pub struct CategorisedLineIterator<'text, 'iter> {
    slices: &'iter CategorisedSlices<'text>,
    idx: usize,
    prev: Option<CategorisedSlice<'text>>,
}
/// The item type of `CategorisedLineIterator`.
///
/// # Note
/// > The type alias is the same as `CategorisedSlices`, so functions such as `construct_text_no_codes` will work.
pub type CategorisedLine<'text> = Vec<CategorisedSlice<'text>>;

impl<'text, 'iter> Iterator for CategorisedLineIterator<'text, 'iter> {
    type Item = CategorisedLine<'text>;
    fn next(&mut self) -> Option<Self::Item> {
        let mut v = Vec::new();

        if let Some(prev) = &self.prev {
            // need to test splitting this, might be more new lines in remainder
            let (first, remainder) = split_on_new_line(prev.text_as_bytes);

            // push first slice on -- only if not empty
            // if first.len() == 0 it is because there is a sequence of new lines
            v.push(prev.clone_style(first));

            if let Some(remainder) = remainder {
                // there is a remainder, which means that a new line was hit
                self.prev = Some(prev.clone_style(remainder));
                return Some(v); // exit early
            }

            self.prev = None; // consumed prev
        }

        while let Some(slice) = self.slices.get(self.idx) {
            self.idx += 1; // increment to next slice, always happens as well split this slice.

            let (first, remainder) = split_on_new_line(slice.text_as_bytes);

            // push first slice on -- only if not empty
            if first.len() > 0 || v.len() == 0 {
                v.push(slice.clone_style(first));
            }

            if let Some(remainder) = remainder {
                // there is a remainder, which means that a new line was hit
                self.prev = Some(slice.clone_style(remainder));
                break; // exit looping
            }
        }

        if v.len() == 0 && self.idx >= self.slices.len() {
            None // stop iterating if no slices were met and the index is above the slices len
        } else {
            Some(v)
        }
    }
}

/// Splits on the first instance of `\r\n` or `\n` bytes.
/// Returns the first split slice, and the remainder slice if there is a split and items afterwards.
/// Will not return an empty remainder slice. Can return empty first slice (say `"\nHello"`);
fn split_on_new_line(txt_slice: &[u8]) -> (&[u8], Option<&[u8]>) {
    let mut split = txt_slice.splitn(2, |byte| byte == &b'\n'); // split on new line byte

    let first = split.next().expect("should be one I guess?"); // get the first return

    let first = if let Some(last) = first.last() {
        if last == &b'\r' {
            first.split_last().expect("there are elements").1
        } else {
            first
        }
    } else {
        first
    };

    match split.next() {
        Some(r) => {
            if r.len() > 0 {
                (first, Some(r))
            } else {
                (first, None)
            }
        }
        None => (first, None),
    }
}

/// Data structure that holds information about colouring and styling of a text slice.
#[derive(Debug, PartialEq, Clone)]
pub struct CategorisedSlice<'text> {
    /// The text slice as a byte array.
    ///
    /// # Note
    /// Once the crate [`parse-ansi`](https://crates.io/crates/parse-ansi) moves to [`regex`](https://crates.io/crates/regex) crate `1.1.0` it will be possible to return a string slice (`&str`).
    pub text_as_bytes: &'text [u8],
    /// The foreground (or text) colour.
    pub fg_colour: Color,
    /// The background colour.
    pub bg_colour: Color,
    /// The emphasis state (bold, faint, normal).
    pub intensity: Intensity,
    /// Italicised.
    pub italic: bool,
    /// Underlined.
    pub underline: bool,
    /// Slow blink text.
    pub blink: bool,
    /// Inverted colours. See [https://en.wikipedia.org/wiki/Reverse_video](https://en.wikipedia.org/wiki/Reverse_video).
    pub reversed: bool,
    /// Invisible text.
    pub hidden: bool,
    /// Struck-through.
    pub strikethrough: bool,
}

impl<'text> CategorisedSlice<'text> {
    fn clone_style(&self, txt_slice: &'text [u8]) -> Self {
        let mut c = self.clone();
        c.text_as_bytes = txt_slice;
        c
    }

    #[cfg(test)]
    fn default_style(txt_slice: &'text [u8]) -> Self {
        let sgr = SGR::default();
        CategorisedSlice {
            text_as_bytes: txt_slice,
            fg_colour: sgr.fg_colour,
            bg_colour: sgr.bg_colour,
            intensity: sgr.intensity.clone(),
            italic: sgr.italic,
            underline: sgr.underline,
            blink: sgr.blink,
            reversed: sgr.reversed,
            hidden: sgr.hidden,
            strikethrough: sgr.strikethrough,
        }
    }
}

/// The formatting components `SGR (Select Graphic Rendition)`.
/// [spec](https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters)
struct SGR {
    fg_colour: Color,
    bg_colour: Color,
    intensity: Intensity,
    italic: bool,
    underline: bool,
    blink: bool,
    reversed: bool,
    hidden: bool,
    strikethrough: bool,
}

/// The emphasis (bold, faint) states.
#[derive(Debug, Clone, PartialEq)]
pub enum Intensity {
    /// Normal intensity (no emphasis).
    Normal,
    /// Bold.
    Bold,
    /// Faint.
    Faint,
}

impl Default for SGR {
    fn default() -> Self {
        SGR {
            fg_colour: Color::White,
            bg_colour: Color::Black,
            intensity: Intensity::Normal,
            italic: false,
            underline: false,
            blink: false,
            reversed: false,
            hidden: false,
            strikethrough: false,
        }
    }
}