use crate::*;

pub struct PhrasePoolView<E: Engine> {
    _engine:     PhantomData<E>,
    /// Collection of phrases
    pub phrases: Vec<Arc<RwLock<Phrase>>>,
    /// Selected phrase
    pub phrase:  usize,
    /// Scroll offset
    pub scroll:  usize,
    /// Mode switch
    pub mode:    Option<PhrasePoolMode>,
    /// Whether this widget is focused
    pub focused: bool,
    /// Whether this widget is entered
    pub entered: bool,
}

/// Modes for phrase pool
pub enum PhrasePoolMode {
    /// Renaming a pattern
    Rename(usize, String),
    /// Editing the length of a pattern
    Length(usize, usize, PhraseLengthFocus),
}

impl<E: Engine> PhrasePoolView<E> {
    pub fn new (phrases: Vec<Arc<RwLock<Phrase>>>) -> Self {
        Self {
            _engine: Default::default(),
            scroll:  0,
            phrase:  0,
            mode:    None,
            focused: false,
            entered: false,
            phrases,
        }
    }
    pub fn len (&self) -> usize {
        self.phrases.len()
    }
    pub fn phrase (&self) -> &Arc<RwLock<Phrase>> {
        &self.phrases[self.phrase]
    }
    pub fn index_before (&self, index: usize) -> usize {
        index.overflowing_sub(1).0.min(self.len() - 1)
    }
    pub fn index_after (&self, index: usize) -> usize {
        (index + 1) % self.len()
    }
    pub fn index_of (&self, phrase: &Phrase) -> Option<usize> {
        for i in 0..self.phrases.len() {
            if *self.phrases[i].read().unwrap() == *phrase { return Some(i) }
        }
        return None
    }
    fn new_phrase (name: Option<&str>, color: Option<ItemColorTriplet>) -> Arc<RwLock<Phrase>> {
        Arc::new(RwLock::new(Phrase::new(
            String::from(name.unwrap_or("(new)")), true, 4 * PPQ, None, color
        )))
    }
    pub fn delete_selected (&mut self) {
        if self.phrase > 0 {
            self.phrases.remove(self.phrase);
            self.phrase = self.phrase.min(self.phrases.len().saturating_sub(1));
        }
    }
    pub fn append_new (&mut self, name: Option<&str>, color: Option<ItemColorTriplet>) {
        self.phrases.push(Self::new_phrase(name, color));
        self.phrase = self.phrases.len() - 1;
    }
    pub fn insert_new (&mut self, name: Option<&str>, color: Option<ItemColorTriplet>) {
        self.phrases.insert(self.phrase + 1, Self::new_phrase(name, color));
        self.phrase += 1;
    }
    pub fn insert_dup (&mut self) {
        let mut phrase = self.phrases[self.phrase].read().unwrap().duplicate();
        phrase.color = ItemColorTriplet::random_near(phrase.color, 0.25);
        self.phrases.insert(self.phrase + 1, Arc::new(RwLock::new(phrase)));
        self.phrase += 1;
    }
    pub fn move_up (&mut self) {
        if self.phrase > 1 {
            self.phrases.swap(self.phrase - 1, self.phrase);
            self.phrase -= 1;
        }
    }
    pub fn move_down (&mut self) {
        if self.phrase < self.phrases.len().saturating_sub(1) {
            self.phrases.swap(self.phrase + 1, self.phrase);
            self.phrase += 1;
        }
    }
}

// TODO: Display phrases always in order of appearance
impl Content for PhrasePoolView<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        let Self { focused, phrases, mode, .. } = self;
        let content = col!(
            (i, phrase) in phrases.iter().enumerate() => Layers::new(|add|{
                let Phrase { ref name, color, length, .. } = *phrase.read().unwrap();
                let mut length = PhraseLength::new(length, None);
                if let Some(PhrasePoolMode::Length(phrase, new_length, focus)) = mode {
                    if *focused && i == *phrase {
                        length.pulses = *new_length;
                        length.focus  = Some(*focus);
                    }
                }
                let length   = length.align_e().fill_x();
                let row1     = lay!(format!(" {i}").align_w().fill_x(), length).fill_x();
                let mut row2 = format!(" {name}");
                if let Some(PhrasePoolMode::Rename(phrase, _)) = mode {
                    if *focused && i == *phrase { row2 = format!("{row2}▄"); }
                };
                let row2 = TuiStyle::bold(row2, true);
                add(&col!(row1, row2).fill_x().bg(color.base.rgb))?;
                Ok(if *focused && i == self.phrase { add(&CORNERS)?; })
            })
        );
        let border_color = if *focused {Color::Rgb(100, 110, 40)} else {Color::Rgb(70, 80, 50)};
        let border       = Lozenge(Style::default().bg(Color::Rgb(40, 50, 30)).fg(border_color));
        let content      = content.fill_xy().bg(Color::Rgb(28, 35, 25)).border(border);
        let title_color  = if *focused {Color::Rgb(150, 160, 90)} else {Color::Rgb(120, 130, 100)};
        let upper_left   = format!("[{}] Phrases", if self.entered {"■"} else {" "});
        let upper_right  = format!("({})", phrases.len());
        lay!(
            content,
            TuiStyle::fg(upper_left.to_string(),  title_color).push_x(1).align_nw().fill_xy(),
            TuiStyle::fg(upper_right.to_string(), title_color).pull_x(1).align_ne().fill_xy(),
        )
    }
}

#[derive(Clone, PartialEq, Debug)]
pub enum PhrasePoolViewCommand {
    Select(usize),
    Edit(PhrasePoolCommand),
    Rename(PhraseRenameCommand),
    Length(PhraseLengthCommand),
}

impl Handle<Tui> for PhrasePoolView<Tui> {
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        PhrasePoolViewCommand::execute_with_state(self, from)
    }
}

impl InputToCommand<Tui, PhrasePoolView<Tui>> for PhrasePoolViewCommand {
    fn input_to_command (state: &PhrasePoolView<Tui>, input: &TuiInput) -> Option<Self> {
        use PhrasePoolViewCommand as Cmd;
        use PhrasePoolCommand     as Edit;
        use PhraseRenameCommand   as Rename;
        use PhraseLengthCommand   as Length;
        match input.event() {
            key!(KeyCode::Up)        => Some(Cmd::Select(0)),
            key!(KeyCode::Down)      => Some(Cmd::Select(0)),
            key!(KeyCode::Char(',')) => Some(Cmd::Edit(Edit::Swap(0, 0))),
            key!(KeyCode::Char('.')) => Some(Cmd::Edit(Edit::Swap(0, 0))),
            key!(KeyCode::Delete)    => Some(Cmd::Edit(Edit::Delete(0))),
            key!(KeyCode::Char('a')) => Some(Cmd::Edit(Edit::Add(0))),
            key!(KeyCode::Char('i')) => Some(Cmd::Edit(Edit::Add(0))),
            key!(KeyCode::Char('d')) => Some(Cmd::Edit(Edit::Duplicate(0))),
            key!(KeyCode::Char('c')) => Some(Cmd::Edit(Edit::RandomColor(0))),
            key!(KeyCode::Char('n')) => Some(Cmd::Rename(Rename::Begin)),
            key!(KeyCode::Char('t')) => Some(Cmd::Length(Length::Begin)),
            _ => match state.mode {
                Some(PhrasePoolMode::Rename(..)) => {
                    Rename::input_to_command(state, input).map(Cmd::Rename)
                },
                Some(PhrasePoolMode::Length(..)) => {
                    Length::input_to_command(state, input).map(Cmd::Length)
                },
                _ => None
            }
        }
    }
}

impl<E: Engine> Command<PhrasePoolView<E>> for PhrasePoolViewCommand {
    fn execute (self, view: &mut PhrasePoolView<E>) -> Perhaps<Self> {
        use PhraseRenameCommand as Rename;
        use PhraseLengthCommand as Length;
        match self {
            Self::Select(phrase) => {
                view.phrase = phrase
            },
            Self::Edit(command) => {
                return Ok(command.execute(&mut view)?.map(Self::Edit))
            }
            Self::Rename(command) => match command {
                Rename::Begin => {
                    view.mode = Some(PhrasePoolMode::Rename(
                        view.phrase,
                        view.phrases[view.phrase].read().unwrap().name.clone()
                    ))
                },
                _ => {
                    return Ok(command.execute(view)?.map(Self::Rename))
                }
            },
            Self::Length(command) => match command {
                Length::Begin => {
                    view.mode = Some(PhrasePoolMode::Length(
                        view.phrase,
                        view.phrases[view.phrase].read().unwrap().length,
                        PhraseLengthFocus::Bar
                    ))
                },
                _ => {
                    return Ok(command.execute(view)?.map(Self::Length))
                }
            },
        }
        Ok(None)
    }
}

#[derive(Copy, Clone, Debug, PartialEq)]
pub enum PhraseLengthCommand {
    Begin,
    Next,
    Prev,
    Inc,
    Dec,
    Set(usize),
    Cancel,
}

impl InputToCommand<Tui, PhrasePoolView<Tui>> for PhraseLengthCommand {
    fn input_to_command (view: &PhrasePoolView<Tui>, from: &TuiInput) -> Option<Self> {
        if let Some(PhrasePoolMode::Length(_, length, _)) = view.mode {
            Some(match from.event() {
                key!(KeyCode::Up)    => Self::Inc,
                key!(KeyCode::Down)  => Self::Dec,
                key!(KeyCode::Right) => Self::Next,
                key!(KeyCode::Left)  => Self::Prev,
                key!(KeyCode::Enter) => Self::Set(length),
                key!(KeyCode::Esc)   => Self::Cancel,
                _ => return None
            })
        } else {
            unreachable!()
        }
    }
}

impl<E: Engine> Command<PhrasePoolView<E>> for PhraseLengthCommand {
    fn execute (self, view: &mut PhrasePoolView<E>) -> Perhaps<Self> {
        use PhraseLengthFocus::*;
        use PhraseLengthCommand::*;
        if let Some(PhrasePoolMode::Length(phrase, ref mut length, ref mut focus)) = view.mode {
            match self {
                Self::Cancel => {
                    view.mode = None;
                },
                Self::Prev => {
                    focus.prev()
                },
                Self::Next => {
                    focus.next()
                },
                Self::Inc => match focus {
                    Bar  => { *length += 4 * PPQ },
                    Beat => { *length += PPQ },
                    Tick => { *length += 1 },
                },
                Self::Dec => match focus {
                    Bar  => { *length = length.saturating_sub(4 * PPQ) },
                    Beat => { *length = length.saturating_sub(PPQ) },
                    Tick => { *length = length.saturating_sub(1) },
                },
                Self::Set(length) => {
                    let mut phrase = view.phrases[phrase].write().unwrap();
                    let old_length = phrase.length;
                    phrase.length = length;
                    view.mode = None;
                    return Ok(Some(Self::Set(old_length)))
                },
                _ => unreachable!()
            }
            Ok(None)
        } else if self == Begin {
            view.mode = Some(PhrasePoolMode::Length(
                view.phrase,
                view.phrases[view.phrase].read().unwrap().length,
                PhraseLengthFocus::Bar
            ));
            Ok(None)
        } else {
            unreachable!()
        }
    }
}

/// Displays and edits phrase length.
pub struct PhraseLength<E: Engine> {
    _engine: PhantomData<E>,
    /// Pulses per beat (quaver)
    pub ppq:    usize,
    /// Beats per bar
    pub bpb:    usize,
    /// Length of phrase in pulses
    pub pulses: usize,
    /// Selected subdivision
    pub focus:  Option<PhraseLengthFocus>,
}

impl<E: Engine> PhraseLength<E> {
    pub fn new (pulses: usize, focus: Option<PhraseLengthFocus>) -> Self {
        Self { _engine: Default::default(), ppq: PPQ, bpb: 4, pulses, focus }
    }
    pub fn bars  (&self) -> usize {
        self.pulses / (self.bpb * self.ppq)
    }
    pub fn beats (&self) -> usize {
        (self.pulses % (self.bpb * self.ppq)) / self.ppq
    }
    pub fn ticks (&self) -> usize {
        self.pulses % self.ppq
    }
    pub fn bars_string  (&self) -> String {
        format!("{}", self.bars())
    }
    pub fn beats_string (&self) -> String {
        format!("{}", self.beats())
    }
    pub fn ticks_string (&self) -> String {
        format!("{:>02}", self.ticks())
    }
}

impl Content for PhraseLength<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        Layers::new(move|add|{
            match self.focus {
                None => add(&row!(
                    " ", self.bars_string(),
                    ".", self.beats_string(),
                    ".", self.ticks_string(),
                    " "
                )),
                Some(PhraseLengthFocus::Bar) => add(&row!(
                    "[", self.bars_string(),
                    "]", self.beats_string(),
                    ".", self.ticks_string(),
                    " "
                )),
                Some(PhraseLengthFocus::Beat) => add(&row!(
                    " ", self.bars_string(),
                    "[", self.beats_string(),
                    "]", self.ticks_string(),
                    " "
                )),
                Some(PhraseLengthFocus::Tick) => add(&row!(
                    " ", self.bars_string(),
                    ".", self.beats_string(),
                    "[", self.ticks_string(),
                    "]"
                )),
            }
        })
    }
}

/// Focused field of `PhraseLength`
#[derive(Copy, Clone)]
pub enum PhraseLengthFocus {
    /// Editing the number of bars
    Bar,
    /// Editing the number of beats
    Beat,
    /// Editing the number of ticks
    Tick,
}

impl PhraseLengthFocus {
    pub fn next (&mut self) {
        *self = match self {
            Self::Bar  => Self::Beat,
            Self::Beat => Self::Tick,
            Self::Tick => Self::Bar,
        }
    }
    pub fn prev (&mut self) {
        *self = match self {
            Self::Bar  => Self::Tick,
            Self::Beat => Self::Bar,
            Self::Tick => Self::Beat,
        }
    }
}

#[derive(Clone, Debug, PartialEq)]
pub enum PhraseRenameCommand {
    Begin,
    Set(String),
    Confirm,
    Cancel,
}

impl InputToCommand<Tui, PhrasePoolView<Tui>> for PhraseRenameCommand {
    fn input_to_command (view: &PhrasePoolView<Tui>, from: &TuiInput) -> Option<Self> {
        if let Some(PhrasePoolMode::Rename(_, ref old_name)) = view.mode {
            Some(match from.event() {
                key!(KeyCode::Char(c))   => {
                    let mut new_name = old_name.clone();
                    new_name.push(*c);
                    Self::Set(new_name)
                },
                key!(KeyCode::Backspace) => {
                    let mut new_name = old_name.clone();
                    new_name.pop();
                    Self::Set(new_name)
                },
                key!(KeyCode::Enter)     => Self::Confirm,
                key!(KeyCode::Esc)       => Self::Cancel,
                _ => return None
            })
        } else {
            unreachable!()
        }
    }
}

impl<E: Engine> Command<PhrasePoolView<E>> for PhraseRenameCommand {
    fn execute (self, view: &mut PhrasePoolView<E>) -> Perhaps<Self> {
        use PhraseRenameCommand::*;
        if let Some(PhrasePoolMode::Rename(phrase, ref mut old_name)) = view.mode {
            match self {
                Set(s) => {
                    view.phrases[phrase].write().unwrap().name = s.into();
                    return Ok(Some(Self::Set(old_name.clone())))
                },
                Confirm => {
                    let old_name = old_name.clone();
                    view.mode = None;
                    return Ok(Some(Self::Set(old_name)))
                },
                Cancel => {
                    let mut phrase = view.phrases[phrase].write().unwrap();
                    phrase.name = old_name.clone();
                },
                _ => unreachable!()
            };
            Ok(None)
        } else if self == Begin {
            view.mode = Some(PhrasePoolMode::Rename(
                view.phrase,
                view.phrases[view.phrase].read().unwrap().name.clone()
            ));
            Ok(None)
        } else {
            unreachable!()
        }
    }
}