//!
//! This widget helps with row-wise editing of table-data.
//!
//! todo: example is missing. this is hard to grasp.
//!

use crate::event::EditOutcome;
use crossterm::event::Event;
use rat_focus::{Focus, HasFocus};
use rat_ftable::event::util::MouseFlags;
use rat_ftable::event::{ct_event, flow, FocusKeys, HandleEvent, Outcome};
use rat_ftable::selection::RowSelection;
use rat_ftable::TableSelection;
use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::prelude::StatefulWidget;
use ratatui::widgets::StatefulWidgetRef;

pub use rat_ftable::edit::EditorWidget;
pub use rat_ftable::{FTable, FTableState};

/// Widget that supports row-wise editing of a table.
///
/// It's parameterized with a `Editor` widget, that renders
/// the input line.
#[derive(Debug)]
pub struct REditTable<'a, Editor: 'a> {
    table: FTable<'a, RowSelection>,
    edit: Editor,
}

/// Edit state for the table.
///
/// If the edit-state is set, this widget switches to edit-mode.
#[derive(Debug, Default)]
pub struct REditTableState<EditorState> {
    /// Backing table.
    pub table: FTableState<RowSelection>,
    /// Editor state.
    pub edit: Option<EditorState>,

    pub mouse: MouseFlags,
}

impl<'a, Editor> REditTable<'a, Editor>
where
    Editor: EditorWidget + 'a,
{
    pub fn new(table: FTable<'a, RowSelection>, edit: Editor) -> Self {
        Self { table, edit }
    }
}

impl<'a, Editor> StatefulWidgetRef for REditTable<'a, Editor>
where
    Editor: EditorWidget + 'a,
{
    type State = REditTableState<Editor::State>;

    fn render_ref(&self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {
        render_ref(self, area, buf, state);
    }
}

impl<'a, Editor> StatefulWidget for REditTable<'a, Editor>
where
    Editor: EditorWidget + 'a,
{
    type State = REditTableState<Editor::State>;

    fn render(self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {
        render_ref(&self, area, buf, state);
    }
}

fn render_ref<'a, Editor>(
    widget: &REditTable<'a, Editor>,
    area: Rect,
    buf: &mut Buffer,
    state: &mut REditTableState<Editor::State>,
) where
    Editor: EditorWidget + 'a,
{
    widget.table.render_ref(area, buf, &mut state.table);

    if let Some(edit_state) = &mut state.edit {
        // expect a selected row
        if let Some(row) = state.table.selected() {
            // but it might be out of view
            if let Some((row_area, cell_areas)) = state.table.row_cells(row) {
                widget
                    .edit
                    .render_ref(row_area, &cell_areas, buf, edit_state);
            }
        }
    }
}

impl<EditorState> HasFocus for REditTableState<EditorState>
where
    EditorState: HasFocus,
{
    fn focus(&self) -> Focus<'_> {
        let mut f = Focus::default();
        if let Some(edit_state) = self.edit.as_ref() {
            f.add_container(edit_state);
        } else {
            f.add_flag(&self.table.focus, self.table.area);
        }
        f
    }
}

impl<EState, EQualifier> HandleEvent<Event, EQualifier, EditOutcome> for REditTableState<EState>
where
    EState: HandleEvent<Event, EQualifier, EditOutcome>,
{
    fn handle(&mut self, event: &Event, qualifier: EQualifier) -> EditOutcome {
        flow!(match event {
            ct_event!(mouse any for m) if self.mouse.doubleclick(self.table.table_area, m) => {
                if self
                    .table
                    .cell_at_clicked((m.column, m.row).into())
                    .is_some()
                {
                    EditOutcome::Edit
                } else {
                    EditOutcome::NotUsed
                }
            }
            _ => EditOutcome::NotUsed,
        });

        if self.table.focus.get() {
            if let Some(edit_state) = self.edit.as_mut() {
                flow!(edit_state.handle(event, qualifier));

                flow!(match event {
                    ct_event!(keycode press Esc) => {
                        EditOutcome::Cancel
                    }
                    ct_event!(keycode press Enter) | ct_event!(keycode press Up) => {
                        EditOutcome::Commit
                    }
                    ct_event!(keycode press Down) => {
                        if self.table.selected() != Some(self.table.rows().saturating_sub(1)) {
                            EditOutcome::Commit
                        } else {
                            EditOutcome::NotUsed
                        }
                    }
                    _ => EditOutcome::NotUsed,
                });

                EditOutcome::NotUsed
            } else {
                if self.table.focus.get() {
                    flow!(match event {
                        ct_event!(keycode press Insert) => {
                            EditOutcome::Insert
                        }
                        ct_event!(keycode press Delete) => {
                            EditOutcome::Remove
                        }
                        ct_event!(keycode press Enter) | ct_event!(keycode press F(2)) => {
                            EditOutcome::Edit
                        }
                        ct_event!(keycode press Down) => 'f: {
                            if let Some((_column, row)) = self.table.selection.lead_selection() {
                                if row == self.table.rows().saturating_sub(1) {
                                    break 'f EditOutcome::Append;
                                }
                            }
                            EditOutcome::NotUsed
                        }
                        _ => {
                            EditOutcome::NotUsed
                        }
                    });

                    match self.table.handle(event, FocusKeys) {
                        Outcome::NotUsed => EditOutcome::NotUsed,
                        Outcome::Unchanged => EditOutcome::Unchanged,
                        Outcome::Changed => EditOutcome::Changed,
                    }
                } else {
                    EditOutcome::Unchanged
                }
            }
        } else {
            EditOutcome::NotUsed
        }
    }
}