//! ## FileTransferActivity
//!
//! `filetransfer_activiy` is the module which implements the Filetransfer activity, which is the main activity afterall

/*
*
*   Copyright (C) 2020 Christian Visintin - christian.visintin1997@gmail.com
*
* 	This file is part of "TermSCP"
*
*   TermSCP 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.
*
*   TermSCP 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 TermSCP.  If not, see <http://www.gnu.org/licenses/>.
*
*/

// Dependencies
extern crate crossterm;
extern crate tui;
extern crate unicode_width;

// locals
use crate::filetransfer::FileTransferProtocol;
use super::{Activity, Context};

// File transfer
use crate::filetransfer::sftp_transfer::SftpFileTransfer;
use crate::filetransfer::FileTransfer;

// Includes
use crossterm::event::Event as InputEvent;
use crossterm::event::KeyCode;
use crossterm::terminal::{disable_raw_mode, enable_raw_mode};
use std::collections::VecDeque;
use std::io::Stdout;
use std::time::Instant;
use tui::{
    backend::CrosstermBackend,
    layout::{Constraint, Direction, Layout, Rect},
    style::{Color, Modifier, Style},
    terminal::Frame,
    text::{Span, Spans, Text},
    widgets::{Block, Borders, Clear, Paragraph, Tabs},
};
use unicode_width::UnicodeWidthStr;

// Types
type DialogCallback = fn();
type OnInputSubmitCallback = fn(String);

/// ### FileTransferParams
///
/// Holds connection parameters for file transfers
pub struct FileTransferParams {
    pub address: String,
    pub port: u16,
    pub protocol: FileTransferProtocol,
    pub username: Option<String>,
    pub password: Option<String>,
}

/// ### InputField
/// 
/// Input field selected
#[derive(std::cmp::PartialEq)]
enum InputField {
    Explorer,
    Logs,
}

/// ### DialogYesNoOption
/// 
/// Current yes/no dialog option
#[derive(std::cmp::PartialEq, Clone)]
enum DialogYesNoOption {
    Yes,
    No,
}

/// ## PopupType
///
/// PopupType describes the type of popup
#[derive(std::cmp::PartialEq, Clone)]
enum PopupType {
    Alert(Color, String),                                               // Block color; Block text
    Fatal(String),                                                      // Must quit after being hidden
    Input(String, OnInputSubmitCallback),                               // Input description; Callback for submit
    Progress(String),                                                   // Progress block text
    Wait(String),                                                       // Wait block text
    YesNo(String, DialogYesNoOption, DialogCallback, DialogCallback),   // Yes, no callback
}

/// ## InputMode
///
/// InputMode describes the current input mode
/// Each input mode handle the input events in a different way
#[derive(std::cmp::PartialEq, Clone)]
enum InputMode {
    Explorer,
    Popup(PopupType),
}

/// ## FileExplorer
///
/// File explorer states
struct FileExplorer {
    pub index: usize,
}

impl FileExplorer {
    /// ### new
    ///
    /// Instantiates a new FileExplorer
    pub fn new() -> FileExplorer {
        FileExplorer { index: 0 }
    }
}

/// ## FileExplorerTab
///
/// File explorer tab
enum FileExplorerTab {
    Local,
    Remote,
}

/// ## LogLevel
///
/// Log level type
enum LogLevel {
    Error,
    Warn,
    Info,
}

/// ## LogRecord
///
/// Log record entry
struct LogRecord {
    pub time: Instant,
    pub level: LogLevel,
    pub msg: String,
}

impl LogRecord {
    /// ### new
    ///
    /// Instantiates a new LogRecord
    pub fn new(level: LogLevel, msg: &str) -> LogRecord {
        LogRecord {
            time: Instant::now(),
            level: level,
            msg: String::from(msg),
        }
    }
}

/// ## FileTransferActivity
///
/// FileTransferActivity is the data holder for the file transfer activity
pub struct FileTransferActivity {
    pub disconnected: bool,             // Has disconnected from remote?
    pub quit: bool,                     // Has quit term scp?
    params: FileTransferParams,         // FT connection params
    client: Box<dyn FileTransfer>,      // File transfer client
    local: FileExplorer,                // Local File explorer state
    remote: FileExplorer,               // Remote File explorer state
    tab: FileExplorerTab,               // Current selected tab
    log_index: usize,                   // Current log index entry selected
    log_records: VecDeque<LogRecord>,   // Log records
    log_size: usize,                    // Log records size (max)
    progress: usize,                    // Current progress percentage
    input_mode: InputMode,              // Current input mode
    input_field: InputField,            // Current selected input mode
    input_txt: String,                  // Input text
}

impl FileTransferActivity {
    /// ### new
    ///
    /// Instantiates a new FileTransferActivity
    pub fn new(params: FileTransferParams) -> FileTransferActivity {
        let protocol: FileTransferProtocol = params.protocol.clone();
        FileTransferActivity {
            disconnected: false,
            quit: false,
            params: params,
            local: FileExplorer::new(),
            remote: FileExplorer::new(),
            tab: FileExplorerTab::Local,
            log_index: 0,
            log_records: VecDeque::with_capacity(256), // 256 events is enough I guess
            log_size: 256, // Must match with capacity
            progress: 0,
            input_mode: InputMode::Explorer,
            input_field: InputField::Explorer,
            input_txt: String::new(),
            client: match protocol {
                FileTransferProtocol::Sftp => Box::new(SftpFileTransfer::new()),
                FileTransferProtocol::Ftp => Box::new(SftpFileTransfer::new()), // FIXME: FTP
            },
        }
    }

    /// ### connect
    /// 
    /// Connect to remote
    fn connect(&mut self) {
        // Connect to remote
        match self.client.connect(self.params.address.clone(), self.params.port, self.params.username.clone(), self.params.password.clone()) {
            Ok(_) => {
                // Set state to explorer
                self.input_mode = InputMode::Explorer;
            },
            Err(err) => {
                // Set popup fatal error
                self.input_mode = InputMode::Popup(PopupType::Fatal(err.msg()));
            }
        }
    }

    /// ### log
    /// 
    /// Add message to log events
    fn log(&mut self, level: LogLevel, msg: &str) {
        // Create log record
        let record: LogRecord = LogRecord::new(level, msg);
        //Check if history overflows the size
        if self.log_records.len() + 1 > self.log_size {
            self.log_records.pop_back(); // Start cleaning events from back
        }
        // Eventually push front the new record
        self.log_records.push_front(record);
        // Set log index
        self.log_index = self.log_records.len();
    }

    /// ### switch_input_field
    /// 
    /// Switch input field based on current input field
    fn switch_input_field(&mut self) {
        self.input_field = match self.input_field {
            InputField::Explorer => InputField::Logs,
            InputField::Logs => InputField::Explorer,
        }
    }

    /// ### handle_input_event
    /// 
    /// Handle input event based on current input mode
    fn handle_input_event(&mut self, context: &mut Context, ev: &InputEvent) {
        match &self.input_mode {
            InputMode::Explorer => self.handle_input_event_mode_explorer(context, ev),
            InputMode::Popup(ptype) => self.handle_input_event_mode_popup(ev, ptype.clone()),
        }
    }

    /// ### handle_input_event_mode_explorer
    /// 
    /// Input event handler for explorer mode
    fn handle_input_event_mode_explorer(&mut self, context: &mut Context, ev: &InputEvent) {
        // Match input field
        match self.input_field {
            InputField::Explorer => match self.tab { // Match current selected tab
                FileExplorerTab::Local => self.handle_input_event_mode_explorer_tab_local(context, ev),
                FileExplorerTab::Remote => self.handle_input_event_mode_explorer_tab_remote(context, ev)
            },
            InputField::Logs => self.handle_input_event_mode_explorer_log(ev)
        }
    }

    /// ### handle_input_event_mode_explorer_tab_local
    /// 
    /// Input event handler for explorer mode when localhost tab is selected
    fn handle_input_event_mode_explorer_tab_local(&mut self, context: &mut Context, ev: &InputEvent) {
        // TODO: implement
    }

    /// ### handle_input_event_mode_explorer_tab_local
    /// 
    /// Input event handler for explorer mode when remote tab is selected
    fn handle_input_event_mode_explorer_tab_remote(&mut self, context: &mut Context, ev: &InputEvent) {
        // TODO: implement
    }

    /// ### handle_input_event_mode_explorer_log
    /// 
    /// Input even handler for explorer mode when log tab is selected
    fn handle_input_event_mode_explorer_log(&mut self, ev: &InputEvent) {
        // Match event
        let records_block: usize = 16;
        match ev {
            InputEvent::Key(key) => {
                match key.code {
                    KeyCode::Tab => self.switch_input_field(), // <TAB> switch tab
                    KeyCode::Up => {
                        // Decrease log index
                        if self.log_index > 0 {
                            self.log_index = self.log_index - 1;
                        }
                    },
                    KeyCode::Down => {
                        // Increase log index
                        if self.log_index + 1 >= self.log_size {
                            self.log_index = self.log_index + 1;
                        }
                    },
                    KeyCode::PageUp => {
                        // Fast decreasing of log index
                        if self.log_index >= records_block {
                            self.log_index = self.log_index - records_block; // Decrease by `records_block` if possible
                        } else {
                            self.log_index = 0; // Set to 0 otherwise
                        }
                    },
                    KeyCode::PageDown => {
                        // Fast increasing of log index
                        if self.log_index + records_block >= self.log_size { // If overflows, set to size
                            self.log_index = self.log_size - 1;
                        } else {
                            self.log_index = self.log_index + records_block; // Increase by `records_block`
                        }
                    }
                    _ => { /* Nothing to do */ }
                }
            }
            _ => { /* Nothing to do */ }
        }
    }

    /// ### handle_input_event_mode_explorer
    /// 
    /// Input event handler for popup mode. Handler is then based on Popup type
    fn handle_input_event_mode_popup(&mut self, ev: &InputEvent, popup: PopupType) {
        match popup {
            PopupType::Alert(_, _) => self.handle_input_event_mode_popup_alert(ev),
            PopupType::Fatal(_) => self.handle_input_event_mode_popup_fatal(ev),
            PopupType::Input(_, cb) => self.handle_input_event_mode_popup_input(ev, cb),
            PopupType::Progress(_) => self.handle_input_event_mode_popup_progress(ev),
            PopupType::Wait(_) => self.handle_input_event_mode_popup_wait(ev),
            PopupType::YesNo(_, opt, yes_cb, no_cb) => self.handle_input_event_mode_popup_yesno(ev, opt, yes_cb, no_cb),
        }
    }

    /// ### handle_input_event_mode_explorer_alert
    /// 
    /// Input event handler for popup alert
    fn handle_input_event_mode_popup_alert(&mut self, ev: &InputEvent) {
        // If enter, close popup
        match ev {
            InputEvent::Key(key) => {
                match key.code {
                    KeyCode::Enter => {
                        // Set input mode back to explorer
                        self.input_mode = InputMode::Explorer;
                    }
                    _ => { /* Nothing to do */ }
                }
            }
            _ => { /* Nothing to do */ }
        }
    }

    /// ### handle_input_event_mode_explorer_alert
    /// 
    /// Input event handler for popup alert
    fn handle_input_event_mode_popup_fatal(&mut self, ev: &InputEvent) {
        // If enter, close popup
        match ev {
            InputEvent::Key(key) => {
                match key.code {
                    KeyCode::Enter => {
                        // Set quit to true; since a fatal error happened
                        self.quit = true;
                    }
                    _ => { /* Nothing to do */ }
                }
            }
            _ => { /* Nothing to do */ }
        }
    }

    /// ### handle_input_event_mode_popup_input
    /// 
    /// Input event handler for input popup
    fn handle_input_event_mode_popup_input(&mut self, ev: &InputEvent, cb: OnInputSubmitCallback) {
        // If enter, close popup, otherwise push chars to input
        match ev {
            InputEvent::Key(key) => {
                match key.code {
                    KeyCode::Enter => {
                        // Submit
                        let input_text: String = self.input_txt.clone();
                        // Clear current input text
                        self.input_txt.clear();
                        // Set mode back to explorer BEFORE CALLBACKS!!! Callback can then overwrite this, clever uh?
                        self.input_mode = InputMode::Explorer;
                        // Call cb
                        cb(input_text);
                    }
                    KeyCode::Char(ch) => self.input_txt.push(ch),
                    _ => { /* Nothing to do */ }
                }
            }
            _ => { /* Nothing to do */ }
        }
    }

    /// ### handle_input_event_mode_explorer_alert
    /// 
    /// Input event handler for popup alert
    fn handle_input_event_mode_popup_progress(&mut self, ev: &InputEvent) {
        // There's nothing you can do here I guess... maybe ctrl+c in the future idk
        match ev {
            _ => { /* Nothing to do */ }
        }
    }

    /// ### handle_input_event_mode_explorer_alert
    /// 
    /// Input event handler for popup alert
    fn handle_input_event_mode_popup_wait(&mut self, ev: &InputEvent) {
        // There's nothing you can do here I guess... maybe ctrl+c in the future idk
        match ev {
            _ => { /* Nothing to do */ }
        }
    }

    /// ### handle_input_event_mode_explorer_alert
    /// 
    /// Input event handler for popup alert
    fn handle_input_event_mode_popup_yesno(&mut self, ev: &InputEvent, opt: DialogYesNoOption, yes_cb: DialogCallback, no_cb: DialogCallback) {
        // If enter, close popup
        match ev {
            InputEvent::Key(key) => {
                match key.code {
                    KeyCode::Enter => {
                        // @! Set input mode to Explorer BEFORE CALLBACKS!!! Callback can then overwrite this, clever uh?
                        self.input_mode = InputMode::Explorer;
                        // Check if user selected yes or not
                        match opt {
                            DialogYesNoOption::No => no_cb(),
                            DialogYesNoOption::Yes => yes_cb()
                        }
                    }
                    _ => { /* Nothing to do */ }
                }
            }
            _ => { /* Nothing to do */ }
        }
    }

    /// ### draw
    ///
    /// Draw UI
    fn draw(&mut self, frame: &mut Frame<CrosstermBackend<Stdout>>) {
        // TODO: implement
    }

    /// ### draw_header
    ///
    /// Draw header
    fn draw_header(&self) -> Paragraph {
        Paragraph::new(" _____                   ____   ____ ____  \n|_   _|__ _ __ _ __ ___ / ___| / ___|  _ \\ \n  | |/ _ \\ '__| '_ ` _ \\\\___ \\| |   | |_) |\n  | |  __/ |  | | | | | |___) | |___|  __/ \n  |_|\\___|_|  |_| |_| |_|____/ \\____|_|    \n")
            .style(Style::default().fg(Color::LightYellow).add_modifier(Modifier::BOLD))
    }

    /// ### draw_footer
    ///
    /// Draw authentication page footer
    fn draw_footer(&self) -> Paragraph {
        // Write header
        let footer = vec![
            Span::styled(
                "<ESC>",
                Style::default()
                    .bg(Color::Cyan)
                    .fg(Color::White)
                    .add_modifier(Modifier::BOLD),
            ),
            Span::raw("quit\t"),
            Span::styled(
                "<TAB>",
                Style::default()
                    .bg(Color::Cyan)
                    .fg(Color::White)
                    .add_modifier(Modifier::BOLD),
            ),
            Span::raw("change input field\t"),
            Span::styled(
                "<RIGHT,LEFT>",
                Style::default()
                    .bg(Color::Cyan)
                    .fg(Color::White)
                    .add_modifier(Modifier::BOLD),
            ),
            Span::raw("change explorer tab\t"),
            Span::styled(
                "<ENTER>",
                Style::default()
                    .bg(Color::Cyan)
                    .fg(Color::White)
                    .add_modifier(Modifier::BOLD),
            ),
            Span::raw("to upload/download file\t"),
            Span::styled(
                "<CTRL+R>",
                Style::default()
                    .bg(Color::Cyan)
                    .fg(Color::White)
                    .add_modifier(Modifier::BOLD),
            ),
            Span::raw("to rename file\t"),
            Span::styled(
                "<CANC>",
                Style::default()
                    .bg(Color::Cyan)
                    .fg(Color::White)
                    .add_modifier(Modifier::BOLD),
            ),
            Span::raw("to delete file\t"),
        ];
        Paragraph::new(Text::from(Spans::from(footer)))
    }
}

/**
 * Activity Trait
 * Keep it clean :)
 * Use methods instead!
 */

impl Activity for FileTransferActivity {
    /// ### on_create
    ///
    /// `on_create` is the function which must be called to initialize the activity.
    /// `on_create` must initialize all the data structures used by the activity
    fn on_create(&mut self, context: &mut Context) {
        // Put raw mode on enabled
        let _ = enable_raw_mode();
        // Clear terminal
        let _ = context.terminal.clear();
    }

    /// ### on_draw
    ///
    /// `on_draw` is the function which draws the graphical interface.
    /// This function must be called at each tick to refresh the interface
    fn on_draw(&mut self, context: &mut Context) {
        // Check if connected
        if ! self.client.is_connected() {
            // Set init state to connecting popup
            self.input_mode = InputMode::Popup(PopupType::Wait(format!("Connecting to {}:{}...", self.params.address, self.params.port)));
            // Force ui draw
            let _ = context.terminal.draw(|f| {
                self.draw(f);
            });
            // Connect to remote
            self.connect();
        }
        // Handle input events FIXME: read one or multiple?
        if let Ok(event) = context.input_hnd.read_event() {
            // Iterate over input events
            if let Some(event) = event {
                self.handle_input_event(context, &event);
            }
        }
        // @! draw interface
        let _ = context.terminal.draw(|f| {
            self.draw(f);
        });
    }

    /// ### on_destroy
    ///
    /// `on_destroy` is the function which cleans up runtime variables and data before terminating the activity.
    /// This function must be called once before terminating the activity.
    fn on_destroy(&mut self, context: &mut Context) {
        // Disable raw mode
        let _ = disable_raw_mode();
        // Clear terminal
        let _ = context.terminal.clear();
        // Disconnect client
        if self.client.is_connected() {
            let _ = self.client.disconnect();
        }
    }
}