//! The grid-details view lists several details views side-by-side.

use std::io::{Write, Result as IOResult};

use ansi_term::ANSIStrings;
use term_grid as grid;

use fs::{Dir, File};
use fs::feature::git::GitCache;
use fs::feature::xattr::FileAttributes;
use fs::filter::FileFilter;

use style::Colours;
use output::cell::TextCell;
use output::details::{Options as DetailsOptions, Row as DetailsRow, Render as DetailsRender};
use output::grid::Options as GridOptions;
use output::file_name::FileStyle;
use output::table::{Table, Row as TableRow, Options as TableOptions};
use output::tree::{TreeParams, TreeDepth};


#[derive(Debug)]
pub struct Options {
    pub grid: GridOptions,
    pub details: DetailsOptions,
    pub row_threshold: RowThreshold,
}

/// The grid-details view can be configured to revert to just a details view
/// (with one column) if it wouldn’t produce enough rows of output.
///
/// Doing this makes the resulting output look a bit better: when listing a
/// small directory of four files in four columns, the files just look spaced
/// out and it’s harder to see what’s going on. So it can be enabled just for
/// larger directory listings.
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum RowThreshold {

    /// Only use grid-details view if it would result in at least this many
    /// rows of output.
    MinimumRows(usize),

    /// Use the grid-details view no matter what.
    AlwaysGrid,
}


pub struct Render<'a> {

    /// The directory that’s being rendered here.
    /// We need this to know which columns to put in the output.
    pub dir: Option<&'a Dir>,

    /// The files that have been read from the directory. They should all
    /// hold a reference to it.
    pub files: Vec<File<'a>>,

    /// How to colour various pieces of text.
    pub colours: &'a Colours,

    /// How to format filenames.
    pub style: &'a FileStyle,

    /// The grid part of the grid-details view.
    pub grid: &'a GridOptions,

    /// The details part of the grid-details view.
    pub details: &'a DetailsOptions,

    /// How to filter files after listing a directory. The files in this
    /// render will already have been filtered and sorted, but any directories
    /// that we recurse into will have to have this applied.
    pub filter: &'a FileFilter,

    /// The minimum number of rows that there need to be before grid-details
    /// mode is activated.
    pub row_threshold: RowThreshold,
}

impl<'a> Render<'a> {

    /// Create a temporary Details render that gets used for the columns of
    /// the grid-details render that's being generated.
    ///
    /// This includes an empty files vector because the files get added to
    /// the table in *this* file, not in details: we only want to insert every
    /// *n* files into each column’s table, not all of them.
    pub fn details(&self) -> DetailsRender<'a> {
        DetailsRender {
            dir: self.dir.clone(),
            files: Vec::new(),
            colours: self.colours,
            style: self.style,
            opts: self.details,
            recurse: None,
            filter: self.filter,
        }
    }

    /// Create a Details render for when this grid-details render doesn’t fit
    /// in the terminal (or something has gone wrong) and we have given up.
    pub fn give_up(self) -> DetailsRender<'a> {
        DetailsRender {
            dir: self.dir,
            files: self.files,
            colours: self.colours,
            style: self.style,
            opts: self.details,
            recurse: None,
            filter: &self.filter,
        }
    }

    // This doesn’t take an IgnoreCache even though the details one does
    // because grid-details has no tree view.

    pub fn render<W: Write>(self, git: Option<&GitCache>, w: &mut W) -> IOResult<()> {
        if let Some((grid, width)) = self.find_fitting_grid(git) {
            write!(w, "{}", grid.fit_into_columns(width))
        }
        else {
            self.give_up().render(git, None, w)
        }
    }

    pub fn find_fitting_grid(&self, git: Option<&GitCache>) -> Option<(grid::Grid, grid::Width)> {
        let options = self.details.table.as_ref().expect("Details table options not given!");

        let drender = self.details();

        let (first_table, _) = self.make_table(options, git, &drender);

        let rows = self.files.iter()
                       .map(|file| first_table.row_for_file(file, file_has_xattrs(file)))
                       .collect::<Vec<TableRow>>();

        let file_names = self.files.iter()
                             .map(|file| self.style.for_file(file, self.colours).paint().promote())
                             .collect::<Vec<TextCell>>();

        let mut last_working_table = self.make_grid(1, options, git, &file_names, rows.clone(), &drender);

        // If we can’t fit everything in a grid 100 columns wide, then
        // something has gone seriously awry
        for column_count in 2..100 {
            let grid = self.make_grid(column_count, options, git, &file_names, rows.clone(), &drender);

            let the_grid_fits = {
                let d = grid.fit_into_columns(column_count);
                d.is_complete() && d.width() <= self.grid.console_width
            };

            if the_grid_fits {
                last_working_table = grid;
            }
            else {
                // If we’ve figured out how many columns can fit in the user’s
                // terminal, and it turns out there aren’t enough rows to
                // make it worthwhile, then just resort to the lines view.
                if let RowThreshold::MinimumRows(thresh) = self.row_threshold {
                    if last_working_table.fit_into_columns(column_count - 1).row_count() < thresh {
                        return None;
                    }
                }

                return Some((last_working_table, column_count - 1));
            }
        }

        None
    }

    fn make_table<'t>(&'a self, options: &'a TableOptions, mut git: Option<&'a GitCache>, drender: &DetailsRender) -> (Table<'a>, Vec<DetailsRow>) {
        match (git, self.dir) {
            (Some(g), Some(d))  => if !g.has_anything_for(&d.path) { git = None },
            (Some(g), None)     => if !self.files.iter().any(|f| g.has_anything_for(&f.path)) { git = None },
            (None,    _)        => {/* Keep Git how it is */},
        }

        let mut table = Table::new(options, git, self.colours);
        let mut rows = Vec::new();

        if self.details.header {
            let row = table.header_row();
            table.add_widths(&row);
            rows.push(drender.render_header(row));
        }

        (table, rows)
    }

    fn make_grid(&'a self, column_count: usize, options: &'a TableOptions, git: Option<&GitCache>, file_names: &[TextCell], rows: Vec<TableRow>, drender: &DetailsRender) -> grid::Grid {

        let mut tables = Vec::new();
        for _ in 0 .. column_count {
            tables.push(self.make_table(options, git, drender));
        }

        let mut num_cells = rows.len();
        if self.details.header {
            num_cells += column_count;
        }

        let original_height = divide_rounding_up(rows.len(), column_count);
        let height = divide_rounding_up(num_cells, column_count);

        for (i, (file_name, row)) in file_names.iter().zip(rows.into_iter()).enumerate() {
            let index = if self.grid.across {
                    i % column_count
                }
                else {
                    i / original_height
                };

            let (ref mut table, ref mut rows) = tables[index];
            table.add_widths(&row);
            let details_row = drender.render_file(row, file_name.clone(), TreeParams::new(TreeDepth::root(), false));
            rows.push(details_row);
        }

        let columns: Vec<_> = tables.into_iter().map(|(table, details_rows)| {
            drender.iterate_with_table(table, details_rows).collect::<Vec<_>>()
        }).collect();

        let direction = if self.grid.across { grid::Direction::LeftToRight }
                                       else { grid::Direction::TopToBottom };

        let mut grid = grid::Grid::new(grid::GridOptions {
            direction:  direction,
            filling:    grid::Filling::Spaces(4),
        });

        if self.grid.across {
            for row in 0 .. height {
                for column in &columns {
                    if row < column.len() {
                        let cell = grid::Cell {
                            contents: ANSIStrings(&column[row].contents).to_string(),
                            width:    *column[row].width,
                        };

                        grid.add(cell);
                    }
                }
            }
        }
        else {
            for column in &columns {
                for cell in column.iter() {
                    let cell = grid::Cell {
                        contents: ANSIStrings(&cell.contents).to_string(),
                        width:    *cell.width,
                    };

                    grid.add(cell);
                }
            }
        }

        grid
    }
}


fn divide_rounding_up(a: usize, b: usize) -> usize {
    let mut result = a / b;
    if a % b != 0 { result += 1; }
    result
}


fn file_has_xattrs(file: &File) -> bool {
    match file.path.attributes() {
        Ok(attrs) => !attrs.is_empty(),
        Err(_) => false,
    }
}