use super::*;
const MAX_COLS: usize = 500;

/// A list of all mail (`Envelope`s) in a `Mailbox`. On `\n` it opens the `Envelope` content in a
/// `Pager`.
pub struct MailListing {
    /// (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,
    // TODO: sorting
    /// Cache current view.
    content: CellBuffer,
    /// If we must redraw on next redraw event
    dirty: bool,
    /// If `self.pager` exists or not.
    unfocused: bool,
    pager: Option<Pager>,
}

impl MailListing {
    /// Helper function to format entry strings for MailListing */
    /* TODO: Make this configurable */
    fn make_entry_string(e: &Envelope, idx: usize) -> String {
        format!("{}    {}    {:.85}",idx,&e.datetime().format("%Y-%m-%d %H:%M:%S").to_string(),e.subject())
    }

    pub fn new() -> Self {
        let content = CellBuffer::new(0, 0, Cell::with_char(' '));
        MailListing {
            cursor_pos: (0, 1, 0),
            new_cursor_pos: (0, 0, 0),
            length: 0,
            content: content,
            dirty: true,
            unfocused: false,
            pager: 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;

        let threaded = context.accounts[self.cursor_pos.0].settings.threaded;
        // Get mailbox as a reference.
        let mailbox = &mut context.accounts[self.cursor_pos.0][self.cursor_pos.1].as_ref().unwrap().as_ref().unwrap();
        // 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)) });

        self.length = if threaded {
            mailbox.threaded_collection.len()
            
        } else {
            mailbox.len()
        };
        let mut 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 content,
                                          Color::Default,
                                          Color::Default,
                                          ((0, 0), (MAX_COLS-1, 0)),
                                          true);
            self.content = content;
            return;
        }


        // TODO: Fix the threaded hell and refactor stuff into seperate functions and/or modules.
        if threaded {
            let mut indentations: Vec<bool> = Vec::with_capacity(6);
            /* Draw threaded view. */
            let mut iter = mailbox
                .threaded_collection
                .iter()
                .enumerate()
                .peekable();
            /* This is just a desugared for loop so that we can use .peek() */
            while let Some((idx, i)) = iter.next() {
                let container = mailbox.thread(*i);
                let indentation = container.indentation();

                assert_eq!(container.has_message(), true);
                match iter.peek() {
                    Some(&(_, x))
                        if mailbox.thread(*x).indentation() == indentation =>
                        {
                            indentations.pop();
                            indentations.push(true);
                        }
                    _ => {
                        indentations.pop();
                        indentations.push(false);
                    }
                }
                if container.has_sibling() {
                    indentations.pop();
                    indentations.push(true);
                }
                let envelope : &Envelope = &mailbox.collection[container.message().unwrap()];
                let fg_color = if !envelope.is_seen() {
                    Color::Byte(0)
                } else {
                    Color::Default
                };
                let bg_color = if !envelope.is_seen() {
                    Color::Byte(251)
                } else if idx % 2 == 0 {
                    Color::Byte(236)
                } else {
                    Color::Default
                };
                let (x, y) = write_string_to_grid(&MailListing::make_thread_entry(envelope, idx, indentation, container, &indentations),
                &mut content,
                fg_color,
                bg_color,
                ((0, idx) , (MAX_COLS-1, idx)), 
                false);
                for x in x..MAX_COLS {
                    content[(x,idx)].set_ch(' ');
                    content[(x,idx)].set_bg(bg_color);
                }

                match iter.peek() {
                    Some(&(_, x))
                        if mailbox.thread(*x).indentation() > indentation =>
                        {
                            indentations.push(false);
                        }
                    Some(&(_, x))
                        if mailbox.thread(*x).indentation() < indentation =>
                        {
                            for _ in 0..(indentation - mailbox.thread(*x).indentation()) {
                                indentations.pop();
                            }
                        }
                    _ => {}
                }
            }
        } else {

            // Populate `CellBuffer` with every entry.
            // TODO: Lazy load?
            let mut idx = 0;
            for y in 0..=self.length {
                if idx >= self.length {
                    /* No more entries left, so fill the rest of the area with empty space */
                    clear_area(&mut content,
                               ((0, y), (MAX_COLS-1, self.length)));
                    break;
                }
                /* Write an entire line for each envelope entry. */
                let envelope: &Envelope = &mailbox.collection[idx];

                let fg_color = if !envelope.is_seen() {
                    Color::Byte(0)
                } else {
                    Color::Default
                };
                let bg_color = if !envelope.is_seen() {
                    Color::Byte(251)
                } else if idx % 2 == 0 {
                    Color::Byte(236)
                } else {
                    Color::Default
                };
                let (x, y)= write_string_to_grid(&MailListing::make_entry_string(envelope, idx),
                &mut content,
                fg_color,
                bg_color,
                ((0, y) , (MAX_COLS-1, y)), 
                false);

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

                idx+=1;
            }

        }

        self.content = content;
    }
    fn highlight_line(&self, grid: &mut CellBuffer, area: Area, idx: usize, context: &Context) {
        let threaded = context.accounts[self.cursor_pos.0].settings.threaded;
        let mailbox = &context.accounts[self.cursor_pos.0][self.cursor_pos.1].as_ref().unwrap().as_ref().unwrap();
        let envelope: &Envelope = if threaded {
            let i = mailbox.threaded_mail(idx);
            &mailbox.collection[i]
        } else {
            &mailbox.collection[idx]
        };

        let fg_color = if !envelope.is_seen() {
            Color::Byte(0)
        } else {
            Color::Default
        };
        let bg_color = if self.cursor_pos.2 == idx {
            Color::Byte(246)
        } else {
            if !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);
    }

    /// 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].iter() {
                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);
    }

    /// Create a pager for the `Envelope` currently under the cursor.
    fn draw_mail_view(&mut self, grid: &mut CellBuffer, area: Area, context: &mut Context) {
        {
            let threaded = context.accounts[self.cursor_pos.0].settings.threaded;
            let mailbox = &mut context.accounts[self.cursor_pos.0][self.cursor_pos.1].as_ref().unwrap().as_ref().unwrap();
            let envelope: &Envelope = if threaded {
                let i = mailbox.threaded_mail(self.cursor_pos.2);
                &mailbox.collection[i]
            } else {
                &mailbox.collection[self.cursor_pos.2]
            };

            let pager_filter = context.settings.pager.filter.clone();
            self.pager = Some(Pager::new(&envelope, pager_filter));
        }
        self.pager.as_mut().map(|p| p.draw(grid, area, context));
    }
    fn make_thread_entry(envelope: &Envelope, idx: usize, indent: usize,
                         container: &Container, indentations: &Vec<bool>) -> String {
        let has_sibling = container.has_sibling();
        let has_parent = container.has_parent();
        let show_subject = container.show_subject();

        let mut s = format!("{} {} ", idx, &envelope.datetime().format("%Y-%m-%d %H:%M:%S").to_string());
        for i in 0..indent {
            if indentations.len() > i && indentations[i]
            {
                s.push('│');
            } else {
                s.push(' ');
            }
            if i > 0 {
                s.push(' ');
            }
        }
        if indent > 0 {
            if has_sibling && has_parent {
                s.push('├');
            } else if has_sibling {
                s.push('┬');
            } else {
                s.push('└');
            }
            s.push('─'); s.push('>');
        }
        s.push_str(&format!(" {}∞ ", envelope.body().count_attachments()));
         
        if show_subject {
            s.push_str(&format!("{:.85}", envelope.subject()));
        }
        s
    }
}

impl Component for MailListing {
    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 {
            let upper_left = upper_left!(area);
            let bottom_right = bottom_right!(area);
            if self.length == 0 && self.dirty {
                clear_area(grid, area);
                context.dirty_areas.push_back(area);
            }

            /* Render the mail body in a pager, basically copy what HSplit does */
            let total_rows = get_y(bottom_right) - get_y(upper_left);
            let pager_ratio = context.settings.pager.pager_ratio;
            let bottom_entity_rows = (pager_ratio*total_rows )/100;

            if bottom_entity_rows > total_rows {
                clear_area(grid, area);
                context.dirty_areas.push_back(area);
                return;
            }
            let mid = get_y(upper_left) + total_rows - bottom_entity_rows;
            self.draw_list(grid,
                           (upper_left, (get_x(bottom_right), get_y(upper_left)+ mid-1)),
                           context);
            if self.length == 0 {
                self.dirty = false;
                return;
            }
            {
                /* TODO: Move the box drawing business in separate functions */
                if get_x(upper_left) > 0 {
                    if grid[(get_x(upper_left) - 1, mid)].ch() == VERT_BOUNDARY {
                        grid[(get_x(upper_left) - 1, mid)].set_ch(LIGHT_VERTICAL_AND_RIGHT);
                    }
                }

                for i in get_x(upper_left)..=get_x(bottom_right) {
                    grid[(i, mid)].set_ch('─');
                }
            }
            // TODO: Make headers view configurable

            /* Draw header */
            let y = 
            {
                let threaded = context.accounts[self.cursor_pos.0].settings.threaded;
                let mailbox = &mut context.accounts[self.cursor_pos.0][self.cursor_pos.1].as_ref().unwrap().as_ref().unwrap();
                let envelope: &Envelope = if threaded {
                    let i = mailbox.threaded_mail(self.cursor_pos.2);
                    &mailbox.collection[i]
                } else {
                    &mailbox.collection[self.cursor_pos.2]
                };

                let (x,y) = write_string_to_grid(&format!("Date: {}", envelope.date_as_str()),
                grid,
                Color::Byte(33),
                Color::Default,
                (set_y(upper_left, mid+1), bottom_right),
                true);
                for x in x..=get_x(bottom_right) {
                    grid[(x, y)].set_ch(' ');
                    grid[(x, y)].set_bg(Color::Default);
                    grid[(x, y)].set_fg(Color::Default);
                }
                let (x,y) = write_string_to_grid(&format!("From: {}", envelope.from()),
                grid,
                Color::Byte(33),
                Color::Default,
                (set_y(upper_left, y+1), bottom_right),
                true);
                for x in x..=get_x(bottom_right) {
                    grid[(x, y)].set_ch(' ');
                    grid[(x, y)].set_bg(Color::Default);
                    grid[(x, y)].set_fg(Color::Default);
                }
                let (x,y) = write_string_to_grid(&format!("To: {}", envelope.to()),
                grid,
                Color::Byte(33),
                Color::Default,
                (set_y(upper_left, y+1), bottom_right),
                true);
                for x in x..=get_x(bottom_right) {
                    grid[(x, y)].set_ch(' ');
                    grid[(x, y)].set_bg(Color::Default);
                    grid[(x, y)].set_fg(Color::Default);
                }
                let (x,y) = write_string_to_grid(&format!("Subject: {}", envelope.subject()),
                grid,
                Color::Byte(33),
                Color::Default,
                (set_y(upper_left, y+1), bottom_right),
                true);
                for x in x..=get_x(bottom_right) {
                    grid[(x, y)].set_ch(' ');
                    grid[(x, y)].set_bg(Color::Default);
                    grid[(x, y)].set_fg(Color::Default);
                }
                let (x, y) = write_string_to_grid(&format!("Message-ID: {}", envelope.message_id_raw()),
                grid,
                Color::Byte(33),
                Color::Default,
                (set_y(upper_left, y+1), bottom_right),
                true);
                for x in x..=get_x(bottom_right) {
                    grid[(x, y)].set_ch(' ');
                    grid[(x, y)].set_bg(Color::Default);
                    grid[(x, y)].set_fg(Color::Default);
                }
                clear_area(grid,
                           (set_y(upper_left, y+1), set_y(bottom_right, y+2)));
                context.dirty_areas.push_back((set_y(upper_left, mid), set_y(bottom_right, y+1)));
                y + 2
            };


            if !self.dirty {
                if let Some(ref mut p) = self.pager {
                    p.draw(grid,
                           ((get_x(upper_left), y), bottom_right),
                           context);
                }
                return;
            }

            self.dirty = false;

            /* Draw body */
            self.draw_mail_view(grid,
                                ((get_x(upper_left), y), bottom_right),
                                context);

        }
    }
    fn process_event(&mut self, event: &UIEvent, context: &mut Context) {
        match event.event_type {
            UIEventType::Input(Key::Up) => {
                if self.cursor_pos.2 > 0 {
                    self.new_cursor_pos.2 -= 1;
                    self.dirty = 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;
                }
            },
            UIEventType::Input(Key::Char('\n')) if self.unfocused == false => {
                self.unfocused = true;
                self.dirty = true;
            },
            UIEventType::Input(Key::Char('m')) if self.unfocused == false => {
                use std::process::{Command, Stdio};
                    /* Kill input thread so that spawned command can be sole receiver of stdin */
                {
                    /* I tried thread::park() here but for some reason it never blocked and always
                     * returned. Spinlocks are also useless because you have to keep the mutex
                     * guard alive til the child process exits, which requires some effort.
                     *
                     * The only problem with this approach is tht the user has to send some input
                     * in order for the input-thread to wake up and realise it should kill itself.
                     *
                     * I tried writing to stdin/tty manually but for some reason rustty didn't
                     * acknowledge it.
                     */

                    /*
                     * tx sends to input-thread and it kills itself.
                     */
                    let tx = context.input_thread();
                    tx.send(true);
                }

                let mut output = Command::new("vim")
                    .stdin(Stdio::inherit())
                    .stdout(Stdio::inherit())
                    .spawn()
                    .expect("failed to execute process") ;

                /*
                 * Main loop will wait on children and when they reap them the loop spawns a new
                 * input-thread
                 */
                context.replies.push_back(UIEvent { id: 0, event_type: UIEventType::Fork(output) });
                context.replies.push_back(UIEvent { id: 0, event_type: UIEventType::ChangeMode(UIMode::Fork) });
                return;
            },
            UIEventType::Input(Key::Esc) | UIEventType::Input(Key::Char('i')) if self.unfocused == true => {
                self.unfocused = false;
                self.dirty = true;
                self.pager = None;

            },
            UIEventType::Input(Key::Char(k @ 'J')) | UIEventType::Input(Key::Char(k @ 'K')) => {
                let folder_length = context.accounts[self.cursor_pos.0].len();
                match k {
                    'J' if folder_length > 0 && 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);
                    },
                    'K' if self.cursor_pos.1 > 0 => {
                        self.new_cursor_pos.1 = self.cursor_pos.1 - 1;
                        self.dirty = true;
                        self.refresh_mailbox(context);
                    },
                    _ => {
                    },
                }
            },
            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);
                    },
                    _ => {
                    },
                }
            },
            UIEventType::RefreshMailbox(_) => {
                self.dirty = true;
                self.pager = None;
            },
            UIEventType::ChangeMode(UIMode::Normal) => {
                self.dirty = true;
            },
            UIEventType::Resize => {
                self.dirty = true;
            },
            _ => {
            },
        }
        if let Some(ref mut p) = self.pager {
            p.process_event(event, context);
        }
    }
    fn is_dirty(&self) -> bool {
        self.dirty || self.pager.as_ref().map(|p| p.is_dirty()).unwrap_or(false)
    }
}