view.rs

use std::env::var_os;

use output::Colours;
use output::{View, Mode, grid, details};
use output::table::{TimeTypes, Environment, SizeFormat, Options as TableOptions};
use output::file_name::{Classify, FileStyle};
use output::time::TimeFormat;

use options::{flags, Misfire};
use options::parser::Matches;

use fs::feature::xattr;
use info::filetype::FileExtensions;


impl View {

    /// Determine which view to use and all of that view’s arguments.
    pub fn deduce(matches: &Matches) -> Result<View, Misfire> {
        let mode = Mode::deduce(matches)?;
        let colours = Colours::deduce(matches)?;
        let style = FileStyle::deduce(matches);
        Ok(View { mode, colours, style })
    }
}


impl Mode {

    /// Determine the mode from the command-line arguments.
    pub fn deduce(matches: &Matches) -> Result<Mode, Misfire> {
        use options::misfire::Misfire::*;

        let long = || {
            if matches.has(&flags::ACROSS) && !matches.has(&flags::GRID) {
                Err(Useless(&flags::ACROSS, true, &flags::LONG))
            }
            else if matches.has(&flags::ONE_LINE) {
                Err(Useless(&flags::ONE_LINE, true, &flags::LONG))
            }
            else {
                Ok(details::Options {
                    table: Some(TableOptions::deduce(matches)?),
                    header: matches.has(&flags::HEADER),
                    xattr: xattr::ENABLED && matches.has(&flags::EXTENDED),
                })
            }
        };

        let long_options_scan = || {
            for option in &[ &flags::BINARY, &flags::BYTES, &flags::INODE, &flags::LINKS,
                             &flags::HEADER, &flags::BLOCKS, &flags::TIME, &flags::GROUP ] {
                if matches.has(option) {
                    return Err(Useless(*option, false, &flags::LONG));
                }
            }

            if cfg!(feature="git") && matches.has(&flags::GIT) {
                Err(Useless(&flags::GIT, false, &flags::LONG))
            }
            else if matches.has(&flags::LEVEL) && !matches.has(&flags::RECURSE) && !matches.has(&flags::TREE) {
                Err(Useless2(&flags::LEVEL, &flags::RECURSE, &flags::TREE))
            }
            else if xattr::ENABLED && matches.has(&flags::EXTENDED) {
                Err(Useless(&flags::EXTENDED, false, &flags::LONG))
            }
            else {
                Ok(())
            }
        };

        let other_options_scan = || {
            if let Some(width) = TerminalWidth::deduce()?.width() {
                if matches.has(&flags::ONE_LINE) {
                    if matches.has(&flags::ACROSS) {
                        Err(Useless(&flags::ACROSS, true, &flags::ONE_LINE))
                    }
                    else {
                        Ok(Mode::Lines)
                    }
                }
                else if matches.has(&flags::TREE) {
                    let details = details::Options {
                        table: None,
                        header: false,
                        xattr: false,
                    };

                    Ok(Mode::Details(details))
                }
                else {
                    let grid = grid::Options {
                        across: matches.has(&flags::ACROSS),
                        console_width: width,
                    };

                    Ok(Mode::Grid(grid))
                }
            }
            else {
                // If the terminal width couldn’t be matched for some reason, such
                // as the program’s stdout being connected to a file, then
                // fallback to the lines view.

                if matches.has(&flags::TREE) {
                    let details = details::Options {
                        table: None,
                        header: false,
                        xattr: false,
                    };

                    Ok(Mode::Details(details))
                }
                else {
                    Ok(Mode::Lines)
                }
            }
        };

        if matches.has(&flags::LONG) {
            let details = long()?;
            if matches.has(&flags::GRID) {
                match other_options_scan()? {
                    Mode::Grid(grid)  => return Ok(Mode::GridDetails(grid, details)),
                    others            => return Ok(others),
                };
            }
            else {
                return Ok(Mode::Details(details));
            }
        }

        long_options_scan()?;

        other_options_scan()
    }
}


/// The width of the terminal requested by the user.
#[derive(PartialEq, Debug)]
enum TerminalWidth {

    /// The user requested this specific number of columns.
    Set(usize),

    /// The terminal was found to have this number of columns.
    Terminal(usize),

    /// The user didn’t request any particular terminal width.
    Unset,
}

impl TerminalWidth {

    /// Determine a requested terminal width from the command-line arguments.
    ///
    /// Returns an error if a requested width doesn’t parse to an integer.
    fn deduce() -> Result<TerminalWidth, Misfire> {
        if let Some(columns) = var_os("COLUMNS").and_then(|s| s.into_string().ok()) {
            match columns.parse() {
                Ok(width)  => Ok(TerminalWidth::Set(width)),
                Err(e)     => Err(Misfire::FailedParse(e)),
            }
        }
        else if let Some(width) = *TERM_WIDTH {
            Ok(TerminalWidth::Terminal(width))
        }
        else {
            Ok(TerminalWidth::Unset)
        }
    }

    fn width(&self) -> Option<usize> {
        match *self {
            TerminalWidth::Set(width)       |
            TerminalWidth::Terminal(width)  => Some(width),
            TerminalWidth::Unset            => None,
        }
    }
}


impl TableOptions {
    fn deduce(matches: &Matches) -> Result<Self, Misfire> {
        Ok(TableOptions {
            env:         Environment::load_all(),
            time_format: TimeFormat::deduce(matches)?,
            size_format: SizeFormat::deduce(matches)?,
            time_types:  TimeTypes::deduce(matches)?,
            inode:  matches.has(&flags::INODE),
            links:  matches.has(&flags::LINKS),
            blocks: matches.has(&flags::BLOCKS),
            group:  matches.has(&flags::GROUP),
            git:    cfg!(feature="git") && matches.has(&flags::GIT),
        })
    }
}


impl SizeFormat {

    /// Determine which file size to use in the file size column based on
    /// the user’s options.
    ///
    /// The default mode is to use the decimal prefixes, as they are the
    /// most commonly-understood, and don’t involve trying to parse large
    /// strings of digits in your head. Changing the format to anything else
    /// involves the `--binary` or `--bytes` flags, and these conflict with
    /// each other.
    fn deduce(matches: &Matches) -> Result<SizeFormat, Misfire> {
        let binary = matches.has(&flags::BINARY);
        let bytes  = matches.has(&flags::BYTES);

        match (binary, bytes) {
            (true,  true )  => Err(Misfire::Conflict(&flags::BINARY, &flags::BYTES)),
            (true,  false)  => Ok(SizeFormat::BinaryBytes),
            (false, true )  => Ok(SizeFormat::JustBytes),
            (false, false)  => Ok(SizeFormat::DecimalBytes),
        }
    }
}


impl TimeFormat {

    /// Determine how time should be formatted in timestamp columns.
    fn deduce(matches: &Matches) -> Result<TimeFormat, Misfire> {
        pub use output::time::{DefaultFormat, ISOFormat};
        const STYLES: &[&str] = &["default", "long-iso", "full-iso", "iso"];

        let word = match matches.get(&flags::TIME_STYLE) {
            Some(w) => w,
            None    => return Ok(TimeFormat::DefaultFormat(DefaultFormat::new())),
        };

        if word == "default" {
            Ok(TimeFormat::DefaultFormat(DefaultFormat::new()))
        }
        else if word == "iso" {
            Ok(TimeFormat::ISOFormat(ISOFormat::new()))
        }
        else if word == "long-iso" {
            Ok(TimeFormat::LongISO)
        }
        else if word == "full-iso" {
            Ok(TimeFormat::FullISO)
        }
        else {
            Err(Misfire::bad_argument(&flags::TIME_STYLE, word, STYLES))
        }
    }
}


static TIMES: &[&str] = &["modified", "accessed", "created"];

impl TimeTypes {

    /// Determine which of a file’s time fields should be displayed for it
    /// based on the user’s options.
    ///
    /// There are two separate ways to pick which fields to show: with a
    /// flag (such as `--modified`) or with a parameter (such as
    /// `--time=modified`). An error is signaled if both ways are used.
    ///
    /// It’s valid to show more than one column by passing in more than one
    /// option, but passing *no* options means that the user just wants to
    /// see the default set.
    fn deduce(matches: &Matches) -> Result<TimeTypes, Misfire> {
        let possible_word = matches.get(&flags::TIME);
        let modified = matches.has(&flags::MODIFIED);
        let created  = matches.has(&flags::CREATED);
        let accessed = matches.has(&flags::ACCESSED);

        if let Some(word) = possible_word {
            if modified {
                Err(Misfire::Useless(&flags::MODIFIED, true, &flags::TIME))
            }
            else if created {
                Err(Misfire::Useless(&flags::CREATED, true, &flags::TIME))
            }
            else if accessed {
                Err(Misfire::Useless(&flags::ACCESSED, true, &flags::TIME))
            }
            else if word == "mod" || word == "modified" {
                Ok(TimeTypes { accessed: false, modified: true,  created: false })
            }
            else if word == "acc" || word == "accessed" {
                Ok(TimeTypes { accessed: true,  modified: false, created: false })
            }
            else if word == "cr" || word == "created" {
                Ok(TimeTypes { accessed: false, modified: false, created: true  })
            }
            else {
                Err(Misfire::bad_argument(&flags::TIME, word, TIMES))
            }
        }
        else if modified || created || accessed {
            Ok(TimeTypes { accessed, modified, created })
        }
        else {
            Ok(TimeTypes::default())
        }
    }
}


/// Under what circumstances we should display coloured, rather than plain,
/// output to the terminal.
///
/// By default, we want to display the colours when stdout can display them.
/// Turning them on when output is going to, say, a pipe, would make programs
/// such as `grep` or `more` not work properly. So the `Automatic` mode does
/// this check and only displays colours when they can be truly appreciated.
#[derive(PartialEq, Debug)]
enum TerminalColours {

    /// Display them even when output isn’t going to a terminal.
    Always,

    /// Display them when output is going to a terminal, but not otherwise.
    Automatic,

    /// Never display them, even when output is going to a terminal.
    Never,
}

impl Default for TerminalColours {
    fn default() -> TerminalColours {
        TerminalColours::Automatic
    }
}

impl TerminalColours {

    /// Determine which terminal colour conditions to use.
    fn deduce(matches: &Matches) -> Result<TerminalColours, Misfire> {
        const COLOURS: &[&str] = &["always", "auto", "never"];

        let word = match matches.get(&flags::COLOR).or_else(|| matches.get(&flags::COLOUR)) {
            Some(w) => w,
            None    => return Ok(TerminalColours::default()),
        };

        if word == "always" {
            Ok(TerminalColours::Always)
        }
        else if word == "auto" || word == "automatic" {
            Ok(TerminalColours::Automatic)
        }
        else if word == "never" {
            Ok(TerminalColours::Never)
        }
        else {
            Err(Misfire::bad_argument(&flags::COLOR, word, COLOURS))
        }
    }
}


impl Colours {
    fn deduce(matches: &Matches) -> Result<Colours, Misfire> {
        use self::TerminalColours::*;

        let tc = TerminalColours::deduce(matches)?;
        if tc == Always || (tc == Automatic && TERM_WIDTH.is_some()) {
            let scale = matches.has(&flags::COLOR_SCALE) || matches.has(&flags::COLOUR_SCALE);
            Ok(Colours::colourful(scale))
        }
        else {
            Ok(Colours::plain())
        }
    }
}



impl FileStyle {
    fn deduce(matches: &Matches) -> FileStyle {
        let classify = Classify::deduce(matches);
        let exts = FileExtensions;
        FileStyle { classify, exts }
    }
}

impl Classify {
    fn deduce(matches: &Matches) -> Classify {
        if matches.has(&flags::CLASSIFY) { Classify::AddFileIndicators }
                                    else { Classify::JustFilenames }
    }
}


// Gets, then caches, the width of the terminal that exa is running in.
// This gets used multiple times above, with no real guarantee of order,
// so it’s easier to just cache it the first time it runs.
lazy_static! {
    static ref TERM_WIDTH: Option<usize> = {
        use term::dimensions;
        dimensions().map(|t| t.0)
    };
}



#[cfg(test)]
mod test {
    use super::*;
    use std::ffi::OsString;
    use options::flags;

    pub fn os(input: &'static str) -> OsString {
        let mut os = OsString::new();
        os.push(input);
        os
    }

    macro_rules! test {
        ($name:ident: $type:ident <- $inputs:expr => $result:expr) => {
            #[test]
            fn $name() {
                use options::parser::{Args, Arg};
                use std::ffi::OsString;

                static TEST_ARGS: &[&Arg] = &[ &flags::BINARY, &flags::BYTES,
                                               &flags::TIME, &flags::MODIFIED, &flags::CREATED, &flags::ACCESSED ];

                let bits = $inputs.as_ref().into_iter().map(|&o| os(o)).collect::<Vec<OsString>>();
                let results = Args(TEST_ARGS).parse(bits.iter());
                assert_eq!($type::deduce(results.as_ref().unwrap()), $result);
            }
        };
    }


    mod size_formats {
        use super::*;

        test!(empty:   SizeFormat <- []                       => Ok(SizeFormat::DecimalBytes));
        test!(binary:  SizeFormat <- ["--binary"]             => Ok(SizeFormat::BinaryBytes));
        test!(bytes:   SizeFormat <- ["--bytes"]              => Ok(SizeFormat::JustBytes));
        test!(both:    SizeFormat <- ["--binary", "--bytes"]  => Err(Misfire::Conflict(&flags::BINARY, &flags::BYTES)));
    }


    mod time_types {
        use super::*;

        // Default behaviour
        test!(empty:     TimeTypes <- []                      => Ok(TimeTypes::default()));
        test!(modified:  TimeTypes <- ["--modified"]          => Ok(TimeTypes { accessed: false,  modified: true,   created: false }));
        test!(m:         TimeTypes <- ["-m"]                  => Ok(TimeTypes { accessed: false,  modified: true,   created: false }));
        test!(time_mod:  TimeTypes <- ["--time=modified"]     => Ok(TimeTypes { accessed: false,  modified: true,   created: false }));
        test!(time_m:    TimeTypes <- ["-tmod"]               => Ok(TimeTypes { accessed: false,  modified: true,   created: false }));

        test!(acc:       TimeTypes <- ["--accessed"]          => Ok(TimeTypes { accessed: true,   modified: false,  created: false }));
        test!(a:         TimeTypes <- ["-u"]                  => Ok(TimeTypes { accessed: true,   modified: false,  created: false }));
        test!(time_acc:  TimeTypes <- ["--time", "accessed"]  => Ok(TimeTypes { accessed: true,   modified: false,  created: false }));
        test!(time_a:    TimeTypes <- ["-t", "acc"]           => Ok(TimeTypes { accessed: true,   modified: false,  created: false }));

        test!(cr:        TimeTypes <- ["--created"]           => Ok(TimeTypes { accessed: false,  modified: false,  created: true  }));
        test!(c:         TimeTypes <- ["-U"]                  => Ok(TimeTypes { accessed: false,  modified: false,  created: true  }));
        test!(time_cr:   TimeTypes <- ["--time=created"]      => Ok(TimeTypes { accessed: false,  modified: false,  created: true  }));
        test!(time_c:    TimeTypes <- ["-tcr"]                => Ok(TimeTypes { accessed: false,  modified: false,  created: true  }));

        // Multiples
        test!(time_uu:    TimeTypes <- ["-uU"]                => Ok(TimeTypes { accessed: true,   modified: false,  created: true  }));

        // Overriding
        test!(time_mc:    TimeTypes <- ["-tcr", "-tmod"]      => Ok(TimeTypes { accessed: false,  modified: true,   created: false }));

        // Errors
        test!(time_tea:  TimeTypes <- ["--time=tea"]  => Err(Misfire::bad_argument(&flags::TIME, &os("tea"), super::TIMES)));
        test!(time_ea:   TimeTypes <- ["-tea"]        => Err(Misfire::bad_argument(&flags::TIME, &os("ea"), super::TIMES)));
    }
}