/*
 * meli - ui crate.
 *
 * Copyright 2017-2018 Manos Pitsidianakis
 *
 * This file is part of meli.
 *
 * meli is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * meli is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with meli. If not, see <http://www.gnu.org/licenses/>.
 */

use super::*;

//use melib::mailbox::backends::BackendOp;

const MAX_COLS: usize = 500;

/// A list of all mail (`Envelope`s) in a `Mailbox`. On `\n` it opens the `Envelope` content in a
/// `ThreadView`.
#[derive(Debug)]
pub struct CompactListing {
    /// (x, y, z): x is accounts, y is folders, z is index inside a folder.
    cursor_pos: (usize, usize, usize),
    new_cursor_pos: (usize, usize, usize),
    length: usize,
    sort: (SortField, SortOrder),
    subsort: (SortField, SortOrder),
    /// Cache current view.
    content: CellBuffer,
    /// If we must redraw on next redraw event
    dirty: bool,
    /// If `self.view` exists or not.
    unfocused: bool,
    view: Option<ThreadView>,
}

impl Default for CompactListing {
    fn default() -> Self {
        Self::new()
    }
}

impl fmt::Display for CompactListing {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "mail")
    }
}

impl CompactListing {
    /// Helper function to format entry strings for CompactListing */
    /* TODO: Make this configurable */
    fn make_entry_string(e: &Envelope, len: usize, idx: usize) -> String {
        if len > 1 {
            format!(
                "{}    {}    {:.85} ({})",
                idx,
                &CompactListing::format_date(e),
                e.subject(),
                len
            )
        } else {
            format!(
                "{}    {}    {:.85}",
                idx,
                &CompactListing::format_date(e),
                e.subject(),
            )
        }
    }

    pub fn new() -> Self {
        let content = CellBuffer::new(0, 0, Cell::with_char(' '));
        CompactListing {
            cursor_pos: (0, 1, 0),
            new_cursor_pos: (0, 0, 0),
            length: 0,
            sort: (Default::default(), Default::default()),
            subsort: (Default::default(), Default::default()),
            content,
            dirty: true,
            unfocused: false,
            view: None,
        }
    }
    /// Fill the `self.content` `CellBuffer` with the contents of the account folder the user has
    /// chosen.
    fn refresh_mailbox(&mut self, context: &mut Context) {
        self.dirty = true;
        self.cursor_pos.2 = 0;
        self.new_cursor_pos.2 = 0;
        self.cursor_pos.1 = self.new_cursor_pos.1;
        self.cursor_pos.0 = self.new_cursor_pos.0;

        // Inform State that we changed the current folder view.
        context.replies.push_back(UIEvent {
            id: 0,
            event_type: UIEventType::RefreshMailbox((self.cursor_pos.0, self.cursor_pos.1)),
        });
        // Get mailbox as a reference.
        //
        loop {
            // TODO: Show progress visually
            if context.accounts[self.cursor_pos.0]
                .status(self.cursor_pos.1)
                .is_ok()
            {
                break;
            }
        }
        let mailbox = &context.accounts[self.cursor_pos.0][self.cursor_pos.1]
            .as_ref()
            .unwrap();

        self.length = mailbox.threads.root_len();
        self.content = CellBuffer::new(MAX_COLS, self.length + 1, Cell::with_char(' '));
        if self.length == 0 {
            write_string_to_grid(
                &format!("Folder `{}` is empty.", mailbox.folder.name()),
                &mut self.content,
                Color::Default,
                Color::Default,
                ((0, 0), (MAX_COLS - 1, 0)),
                true,
            );
            return;
        }
        let threads = &mailbox.threads;
        threads.sort_by(self.sort, self.subsort, &mailbox.collection);
        for (idx, (t, len, has_unseen)) in threads.root_set_iter().enumerate() {
            let container = &threads.containers()[t];
            let i = if let Some(i) = container.message() {
                i
            } else {
                threads.containers()[container.first_child().unwrap()]
                    .message()
                    .unwrap()
            };
            let root_envelope: &Envelope = &mailbox.collection[i];
            let fg_color = if has_unseen {
                Color::Byte(0)
            } else {
                Color::Default
            };
            let bg_color = if has_unseen {
                Color::Byte(251)
            } else if idx % 2 == 0 {
                Color::Byte(236)
            } else {
                Color::Default
            };
            let (x, _) = write_string_to_grid(
                &CompactListing::make_entry_string(root_envelope, len, idx),
                &mut self.content,
                fg_color,
                bg_color,
                ((0, idx), (MAX_COLS - 1, idx)),
                false,
            );

            for x in x..MAX_COLS {
                self.content[(x, idx)].set_ch(' ');
                self.content[(x, idx)].set_bg(bg_color);
            }
        }
    }

    fn highlight_line(&self, grid: &mut CellBuffer, area: Area, idx: usize, context: &Context) {
        if idx == self.cursor_pos.2 {
            let mailbox = &context.accounts[self.cursor_pos.0][self.cursor_pos.1]
                .as_ref()
                .unwrap();
            let threads = &mailbox.threads;
            let container = threads.root_set()[idx];
            let container = &threads.containers()[container];
            let i = if let Some(i) = container.message() {
                i
            } else {
                threads.containers()[container.first_child().unwrap()]
                    .message()
                    .unwrap()
            };
            let root_envelope: &Envelope = &mailbox.collection[i];
            let fg_color = if !root_envelope.is_seen() {
                Color::Byte(0)
            } else {
                Color::Default
            };
            let bg_color = if self.cursor_pos.2 == idx {
                Color::Byte(246)
            } else if !root_envelope.is_seen() {
                Color::Byte(251)
            } else if idx % 2 == 0 {
                Color::Byte(236)
            } else {
                Color::Default
            };
            change_colors(grid, area, fg_color, bg_color);
            return;
        }

        let (width, height) = self.content.size();
        copy_area(
            grid,
            &self.content,
            area,
            ((0, idx), (width - 1, height - 1)),
        );
    }

    /// Draw the list of `Envelope`s.
    fn draw_list(&mut self, grid: &mut CellBuffer, area: Area, context: &mut Context) {
        if self.cursor_pos.1 != self.new_cursor_pos.1 {
            self.refresh_mailbox(context);
        }
        let upper_left = upper_left!(area);
        let bottom_right = bottom_right!(area);
        if self.length == 0 {
            clear_area(grid, area);
            copy_area(grid, &self.content, area, ((0, 0), (MAX_COLS - 1, 0)));
            context.dirty_areas.push_back(area);
            return;
        }
        let rows = get_y(bottom_right) - get_y(upper_left) + 1;
        let prev_page_no = (self.cursor_pos.2).wrapping_div(rows);
        let page_no = (self.new_cursor_pos.2).wrapping_div(rows);

        let top_idx = page_no * rows;

        /* If cursor position has changed, remove the highlight from the previous position and
         * apply it in the new one. */
        if self.cursor_pos.2 != self.new_cursor_pos.2 && prev_page_no == page_no {
            let old_cursor_pos = self.cursor_pos;
            self.cursor_pos = self.new_cursor_pos;
            for idx in &[old_cursor_pos.2, self.new_cursor_pos.2] {
                if *idx >= self.length {
                    continue; //bounds check
                }
                let new_area = (
                    set_y(upper_left, get_y(upper_left) + (*idx % rows)),
                    set_y(bottom_right, get_y(upper_left) + (*idx % rows)),
                );
                self.highlight_line(grid, new_area, *idx, context);
                context.dirty_areas.push_back(new_area);
            }
            return;
        } else if self.cursor_pos != self.new_cursor_pos {
            self.cursor_pos = self.new_cursor_pos;
        }

        /* Page_no has changed, so draw new page */
        copy_area(
            grid,
            &self.content,
            area,
            ((0, top_idx), (MAX_COLS - 1, self.length)),
        );
        self.highlight_line(
            grid,
            (
                set_y(upper_left, get_y(upper_left) + (self.cursor_pos.2 % rows)),
                set_y(bottom_right, get_y(upper_left) + (self.cursor_pos.2 % rows)),
            ),
            self.cursor_pos.2,
            context,
        );
        context.dirty_areas.push_back(area);
    }

    fn format_date(envelope: &Envelope) -> String {
        let d = std::time::UNIX_EPOCH + std::time::Duration::from_secs(envelope.date());
        let now: std::time::Duration = std::time::SystemTime::now().duration_since(d).unwrap();
        match now.as_secs() {
            n if n < 10 * 60 * 60 => format!("{} hours ago{}", n / (60 * 60), " ".repeat(8)),
            n if n < 24 * 60 * 60 => format!("{} hours ago{}", n / (60 * 60), " ".repeat(7)),
            n if n < 4 * 24 * 60 * 60 => {
                format!("{} days ago{}", n / (24 * 60 * 60), " ".repeat(9))
            }
            _ => envelope.datetime().format("%Y-%m-%d %H:%M:%S").to_string(),
        }
    }
}

impl Component for CompactListing {
    fn draw(&mut self, grid: &mut CellBuffer, area: Area, context: &mut Context) {
        if !self.unfocused {
            if !self.is_dirty() {
                return;
            }
            self.dirty = false;
            /* Draw the entire list */
            self.draw_list(grid, area, context);
        } else {
            if self.length == 0 && self.dirty {
                clear_area(grid, area);
                context.dirty_areas.push_back(area);
                return;
            }

            /* Render the mail body in a pager */
            if !self.dirty {
                if let Some(v) = self.view.as_mut() {
                    v.draw(grid, area, context);
                }
                return;
            }
            self.view = Some(ThreadView::new(self.cursor_pos, None, context));
            self.view.as_mut().unwrap().draw(grid, area, context);
            self.dirty = false;
        }
    }
    fn process_event(&mut self, event: &UIEvent, context: &mut Context) -> bool {
        if let Some(ref mut v) = self.view {
            if v.process_event(event, context) {
                return true;
            }
        }
        match event.event_type {
            UIEventType::Input(Key::Up) => {
                if self.cursor_pos.2 > 0 {
                    self.new_cursor_pos.2 = self.new_cursor_pos.2.saturating_sub(1);
                    self.dirty = true;
                }
                return true;
            }
            UIEventType::Input(Key::Down) => {
                if self.length > 0 && self.new_cursor_pos.2 < self.length - 1 {
                    self.new_cursor_pos.2 += 1;
                    self.dirty = true;
                }
                return true;
            }
            UIEventType::Input(Key::Char('\n')) if !self.unfocused => {
                self.unfocused = true;
                self.dirty = true;
                return true;
            }
            UIEventType::Input(Key::Char('i')) if self.unfocused => {
                self.unfocused = false;
                self.dirty = true;
                self.view = None;
                return true;
            }
            UIEventType::Input(Key::Char(k @ 'J')) | UIEventType::Input(Key::Char(k @ 'K')) => {
                let folder_length = context.accounts[self.cursor_pos.0].len();
                let accounts_length = context.accounts.len();
                match k {
                    'J' if folder_length > 0 => {
                        if self.new_cursor_pos.1 < folder_length - 1 {
                            self.new_cursor_pos.1 = self.cursor_pos.1 + 1;
                            self.dirty = true;
                            self.refresh_mailbox(context);
                        } else if accounts_length > 0 && self.new_cursor_pos.0 < accounts_length - 1
                        {
                            self.new_cursor_pos.0 = self.cursor_pos.0 + 1;
                            self.new_cursor_pos.1 = 0;
                            self.dirty = true;
                            self.refresh_mailbox(context);
                        }
                    }
                    'K' => {
                        if self.cursor_pos.1 > 0 {
                            self.new_cursor_pos.1 = self.cursor_pos.1 - 1;
                            self.dirty = true;
                            self.refresh_mailbox(context);
                        } else if self.cursor_pos.0 > 0 {
                            self.new_cursor_pos.0 = self.cursor_pos.0 - 1;
                            self.new_cursor_pos.1 = 0;
                            self.dirty = true;
                            self.refresh_mailbox(context);
                        }
                    }
                    _ => {}
                }
                return true;
            }
            UIEventType::Input(Key::Char(k @ 'h')) | UIEventType::Input(Key::Char(k @ 'l')) => {
                let accounts_length = context.accounts.len();
                match k {
                    'h' if accounts_length > 0 && self.new_cursor_pos.0 < accounts_length - 1 => {
                        self.new_cursor_pos.0 = self.cursor_pos.0 + 1;
                        self.new_cursor_pos.1 = 0;
                        self.dirty = true;
                        self.refresh_mailbox(context);
                    }
                    'l' if self.cursor_pos.0 > 0 => {
                        self.new_cursor_pos.0 = self.cursor_pos.0 - 1;
                        self.new_cursor_pos.1 = 0;
                        self.dirty = true;
                        self.refresh_mailbox(context);
                    }
                    _ => {}
                }
                return true;
            }
            UIEventType::RefreshMailbox(_) => {
                self.dirty = true;
                self.view = None;
            }
            UIEventType::MailboxUpdate((ref idxa, ref idxf)) => {
                if *idxa == self.new_cursor_pos.0 && *idxf == self.new_cursor_pos.1 {
                    self.dirty = true;
                    self.refresh_mailbox(context);
                }
            }
            UIEventType::ChangeMode(UIMode::Normal) => {
                self.dirty = true;
            }
            UIEventType::Resize => {
                self.dirty = true;
            }
            UIEventType::Action(ref action) => match action {
                Action::ViewMailbox(idx) => {
                    self.new_cursor_pos.1 = *idx;
                    self.dirty = true;
                    self.refresh_mailbox(context);
                    return true;
                }
                Action::SubSort(field, order) => {
                    eprintln!("SubSort {:?} , {:?}", field, order);
                    self.subsort = (*field, *order);
                    self.dirty = true;
                    self.refresh_mailbox(context);
                    return true;
                }
                Action::Sort(field, order) => {
                    eprintln!("Sort {:?} , {:?}", field, order);
                    self.sort = (*field, *order);
                    self.dirty = true;
                    self.refresh_mailbox(context);
                    return true;
                }
                _ => {}
            },
            _ => {}
        }
        false
    }
    fn is_dirty(&self) -> bool {
        self.dirty || self.view.as_ref().map(|p| p.is_dirty()).unwrap_or(false)
    }
    fn set_dirty(&mut self) {
        if let Some(p) = self.view.as_mut() {
            p.set_dirty();
        }
        self.dirty = true;
    }
}