tix-tracker 0.4.0

use ratatui::Frame;
use ratatui::layout::{Position, Rect};
use ratatui::style::{Color, Modifier, Style};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Borders, Paragraph};

use crate::model::Issue;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FormFocus {
    Title,
    Status,
    Priority,
    Labels,
    Assignee,
    Estimate,
    Cycles,
    Milestones,
    Reviewer,
    StartDate,
    DueDate,
    /// The parent issue (WP06 / T026). Appended **last**, not slotted next to
    /// `Assignee` where it would read better: every existing row's index is the
    /// identity of that row in `render_with_bindings`'s `fields` array, and
    /// inserting in the middle renumbers all five rows after it. Appending keeps
    /// the eleven existing indices stable, so no render or golden assertion moves.
    Parent,
}

impl FormFocus {
    pub fn next(self) -> Self {
        match self {
            FormFocus::Title => FormFocus::Status,
            FormFocus::Status => FormFocus::Priority,
            FormFocus::Priority => FormFocus::Labels,
            FormFocus::Labels => FormFocus::Assignee,
            FormFocus::Assignee => FormFocus::Estimate,
            FormFocus::Estimate => FormFocus::Cycles,
            FormFocus::Cycles => FormFocus::Milestones,
            FormFocus::Milestones => FormFocus::Reviewer,
            FormFocus::Reviewer => FormFocus::StartDate,
            FormFocus::StartDate => FormFocus::DueDate,
            FormFocus::DueDate => FormFocus::Parent,
            FormFocus::Parent => FormFocus::Title,
        }
    }

    pub fn prev(self) -> Self {
        match self {
            // `Parent`, not `DueDate`: `RING` now ends at `Parent`, and the two
            // must agree or the backward wrap lands on a different field than the
            // forward one. This drift was real — `form_arrows_navigate_fields` is
            // what caught it, and it is why that test compares against `RING` now
            // instead of a literal.
            FormFocus::Title => FormFocus::Parent,
            FormFocus::Status => FormFocus::Title,
            FormFocus::Priority => FormFocus::Status,
            FormFocus::Labels => FormFocus::Priority,
            FormFocus::Assignee => FormFocus::Labels,
            FormFocus::Estimate => FormFocus::Assignee,
            FormFocus::Cycles => FormFocus::Estimate,
            FormFocus::Milestones => FormFocus::Cycles,
            FormFocus::Reviewer => FormFocus::Milestones,
            FormFocus::StartDate => FormFocus::Reviewer,
            FormFocus::DueDate => FormFocus::StartDate,
            FormFocus::Parent => FormFocus::DueDate,
        }
    }

    pub fn label(self) -> &'static str {
        match self {
            FormFocus::Title => "Title",
            FormFocus::Status => "Status",
            FormFocus::Priority => "Priority",
            FormFocus::Labels => "Labels",
            FormFocus::Assignee => "Assignee",
            FormFocus::Estimate => "Estimate",
            FormFocus::Cycles => "Cycles",
            FormFocus::Milestones => "Milestones",
            FormFocus::Reviewer => "Reviewer",
            FormFocus::StartDate => "Start date",
            FormFocus::DueDate => "Due date",
            FormFocus::Parent => "Parent",
        }
    }

    /// The focus ring, in `next()` order, starting at `Title`.
    ///
    /// One list, so `render_with_bindings` can derive both the focus index and the
    /// row labels from it. It used to hold a hand-written `match` for the index
    /// beside a positional array of labels, which agree only by inspection — and
    /// the two disagree *silently*, as a bold cursor on the wrong row.
    pub const RING: [FormFocus; 12] = [
        FormFocus::Title,
        FormFocus::Status,
        FormFocus::Priority,
        FormFocus::Labels,
        FormFocus::Assignee,
        FormFocus::Estimate,
        FormFocus::Cycles,
        FormFocus::Milestones,
        FormFocus::Reviewer,
        FormFocus::StartDate,
        FormFocus::DueDate,
        FormFocus::Parent,
    ];

    /// This field's row in [`FormFocus::RING`].
    pub fn index(self) -> usize {
        Self::RING
            .iter()
            .position(|f| *f == self)
            .expect("every FormFocus variant is in RING")
    }

    /// Whether this field holds a date (picker-only, no free typing).
    pub fn is_date(self) -> bool {
        matches!(self, FormFocus::StartDate | FormFocus::DueDate)
    }

    /// Whether this field holds a parent (picker-only, single-select).
    pub fn is_parent(self) -> bool {
        matches!(self, FormFocus::Parent)
    }

    /// Whether the field's value is **chosen** from a picker rather than typed.
    ///
    /// Typing is refused on these, because a half-typed number or a hand-typed
    /// title is not a value: the service validates a parent by resolved number, so
    /// free text here could only ever fail. This is the general form of what
    /// `is_date` was already doing for dates alone.
    pub fn is_picker_only(self) -> bool {
        self.is_date() || self.is_parent()
    }
}

#[derive(Debug, Clone)]
pub struct FormState {
    pub title: String,
    pub status: String,
    pub priority: String,
    pub labels: String,
    pub assignee: String,
    pub estimate: String,
    pub cycles: String,
    pub milestones: String,
    pub reviewer: String,
    pub start_date: String,
    pub due_date: String,
    /// The chosen parent's **number**, as a string (WP06 / T026).
    ///
    /// A `String` for the same reason `assignee` is one: the form's fields are
    /// uniformly text, and each is parsed and validated at submit rather than at
    /// the keystroke. Empty means no parent, which carries the same meaning as an
    /// empty `--parent ""` on the CLI.
    pub parent: String,
    pub focus: FormFocus,
}

impl FormState {
    pub fn new(default_status: &str) -> Self {
        Self::with_default_assignee(default_status, "")
    }

    pub fn with_default_assignee(default_status: &str, default_assignee: &str) -> Self {
        FormState {
            title: String::new(),
            status: default_status.to_string(),
            priority: String::new(),
            labels: String::new(),
            assignee: default_assignee.to_string(),
            estimate: String::new(),
            cycles: String::new(),
            milestones: String::new(),
            reviewer: String::new(),
            start_date: String::new(),
            due_date: String::new(),
            parent: String::new(),
            focus: FormFocus::Title,
        }
    }

    /// This form with every field prefilled from an existing issue — the TUI's
    /// "clone issue" action (tix #1484).
    ///
    /// Exactly the fields the form *has* are carried over, which is exactly the
    /// fields creation takes: `number`, `created`, `commit` and `History` are not
    /// creation inputs, so they are not carried. The title is copied **verbatim**
    /// rather than suffixed with "copy": the user asked for the source's data, a
    /// title is not an identity (numbers are), and inventing a naming convention
    /// here would put a string in the user's issue that no command in this tool
    /// produces.
    ///
    /// Multivalued fields are filled in the same comma-separated form the submit
    /// path parses (`labels`, `cycles`, `milestones`), so a clone submitted
    /// unchanged round-trips the source's values exactly.
    pub fn from_issue(issue: &Issue) -> Self {
        fn joined(values: &Option<Vec<String>>) -> String {
            values.as_deref().map(|v| v.join(",")).unwrap_or_default()
        }
        FormState {
            title: issue.title.clone(),
            status: issue.status.to_string(),
            priority: issue.priority.to_string(),
            labels: issue.labels.join(","),
            assignee: issue.assignee.clone().unwrap_or_default(),
            estimate: issue.estimate.clone().unwrap_or_default(),
            cycles: joined(&issue.cycles),
            milestones: joined(&issue.milestones),
            reviewer: issue.reviewer.clone().unwrap_or_default(),
            start_date: issue.start_date.clone().unwrap_or_default(),
            due_date: issue.due_date.clone().unwrap_or_default(),
            parent: issue.parent.map(|n| n.to_string()).unwrap_or_default(),
            focus: FormFocus::Title,
        }
    }

    /// This form's value for `focus`, regardless of which field is focused.
    ///
    /// `focused_value` is `value_of(self.focus)`. The indirection exists so the
    /// renderer can walk [`FormFocus::RING`] and read each field in turn, which is
    /// what lets one list drive both the labels and the focus index.
    pub fn value_of(&self, focus: FormFocus) -> &str {
        match focus {
            FormFocus::Title => &self.title,
            FormFocus::Status => &self.status,
            FormFocus::Priority => &self.priority,
            FormFocus::Labels => &self.labels,
            FormFocus::Assignee => &self.assignee,
            FormFocus::Estimate => &self.estimate,
            FormFocus::Cycles => &self.cycles,
            FormFocus::Milestones => &self.milestones,
            FormFocus::Reviewer => &self.reviewer,
            FormFocus::StartDate => &self.start_date,
            FormFocus::DueDate => &self.due_date,
            FormFocus::Parent => &self.parent,
        }
    }

    pub fn focused_value(&self) -> &str {
        self.value_of(self.focus)
    }

    pub fn focused_value_mut(&mut self) -> &mut String {
        match self.focus {
            FormFocus::Title => &mut self.title,
            FormFocus::Status => &mut self.status,
            FormFocus::Priority => &mut self.priority,
            FormFocus::Labels => &mut self.labels,
            FormFocus::Assignee => &mut self.assignee,
            FormFocus::Estimate => &mut self.estimate,
            FormFocus::Cycles => &mut self.cycles,
            FormFocus::Milestones => &mut self.milestones,
            FormFocus::Reviewer => &mut self.reviewer,
            FormFocus::StartDate => &mut self.start_date,
            FormFocus::DueDate => &mut self.due_date,
            FormFocus::Parent => &mut self.parent,
        }
    }

    pub fn insert_char(&mut self, c: char) {
        if self.focus.is_parent() {
            // A parent is picked, never typed.
            return;
        }
        if self.focus.is_date() {
            if let Some(next) = crate::ui::date_picker::type_date(self.focused_value(), c) {
                *self.focused_value_mut() = next;
            }
            return;
        }
        let value = self.focused_value_mut();
        value.push(c);
    }

    pub fn delete_char(&mut self) {
        if self.focus.is_parent() {
            return;
        }
        if self.focus.is_date() {
            let next = crate::ui::date_picker::backspace_date(self.focused_value());
            *self.focused_value_mut() = next;
            return;
        }
        let value = self.focused_value_mut();
        value.pop();
    }

    /// Whether the focused field is a picker-only date field.
    pub fn is_date_focus(&self) -> bool {
        self.focus.is_date()
    }

    /// Whether the focused date field already holds a complete, valid date.
    pub fn focused_date_is_complete(&self) -> bool {
        self.focus.is_date() && crate::ui::date_picker::is_complete_date(self.focused_value())
    }

    /// Overwrite the focused date field (no-op when it isn't a date field).
    pub fn set_focused_date(&mut self, value: &str) {
        if self.focus.is_date() {
            *self.focused_value_mut() = value.to_string();
        }
    }

    pub fn move_focus_next(&mut self) {
        self.focus = self.focus.next();
    }

    pub fn move_focus_prev(&mut self) {
        self.focus = self.focus.prev();
    }
}

pub fn render(form: &FormState, f: &mut Frame, area: Rect) {
    let bindings =
        crate::keybindings::KeyBindings::resolve(&crate::keybindings::KeyBindings::default())
            .expect("built-in bindings are valid");
    render_with_bindings(
        form,
        f,
        area,
        &bindings,
        crate::keybindings::InputContext::Form,
    );
    // This entry point renders the form as the active surface, so it places the
    // caret too. `render_with_bindings` cannot: it is also what draws the form as a
    // backdrop under a picker, where the cursor belongs to the overlay.
    place_caret(form, f, area);
}

pub fn render_with_bindings(
    form: &FormState,
    f: &mut Frame,
    area: Rect,
    bindings: &crate::keybindings::EffectiveBindings,
    context: crate::keybindings::InputContext,
) {
    // Both the focus index and the row labels come from `FormFocus::RING`, so the
    // cursor and the label it labels cannot drift apart. The value for each field
    // is read through `focused_value`-style indexing into `FormState` below, which
    // is why the pairing is by position and not by name.
    let focus_idx = form.focus.index();
    let fields: Vec<(&'static str, &str)> = FormFocus::RING
        .iter()
        .map(|focus| (focus.label(), form.value_of(*focus)))
        .collect();

    let mut lines: Vec<Line<'static>> = Vec::new();
    for (i, (label, value)) in fields.iter().enumerate() {
        let cursor = if i == focus_idx { "> " } else { "  " };
        let label_style = if i == focus_idx {
            Style::default()
                .add_modifier(Modifier::BOLD)
                .fg(Color::Cyan)
        } else {
            Style::default()
        };
        let (display, value_style) = if value.is_empty() && i != focus_idx {
            ("(empty)".to_string(), Style::default().fg(Color::DarkGray))
        } else if i == focus_idx {
            (
                value.to_string(),
                Style::default().add_modifier(Modifier::UNDERLINED),
            )
        } else {
            (value.to_string(), Style::default())
        };
        lines.push(Line::from(vec![
            Span::styled(format!("{cursor}{label}: "), label_style),
            Span::styled(display, value_style),
        ]));
    }

    lines.push(Line::from(""));
    let submit = bindings.label(context, crate::keybindings::TuiAction::Submit);
    let cancel = bindings.label(context, crate::keybindings::TuiAction::Cancel);
    let next = bindings.label(context, crate::keybindings::TuiAction::Next);
    let previous = bindings.label(context, crate::keybindings::TuiAction::Previous);
    let picker = bindings.label(context, crate::keybindings::TuiAction::OpenPicker);
    lines.push(Line::from(Span::styled(
        format!(
            "{submit}: Submit | {cancel}: Cancel | {next}/{previous}: Fields | {picker}: Date/Parent"
        ),
        Style::default().fg(Color::DarkGray),
    )));

    let para =
        Paragraph::new(lines).block(Block::default().borders(Borders::ALL).title("Create Issue"));

    f.render_widget(para, area);
}

/// Where the terminal caret belongs for `form` rendered into `area`, or `None`
/// when this form shows no insertion point.
///
/// Split from [`place_caret`] so the arithmetic — the part that can be wrong — is
/// testable without a terminal.
///
/// The form is **append-only** editing: `insert_char` pushes and `delete_char`
/// pops, so the insertion point is always the end of the focused value's text and
/// that is where the caret belongs. A picker-only field gets none, because
/// `insert_char` returns early on it: a caret on `Parent` would advertise an
/// insertion point that does not exist. The date fields do accept typed digits, so
/// they keep one.
///
/// A value wider than the field is clipped by `Paragraph` (which does not wrap
/// here) and its true caret is off-screen, so the column is clamped into the
/// visible row rather than handed back out of bounds. Making the value scroll is a
/// larger change than this fix.
pub fn caret_position(form: &FormState, area: Rect) -> Option<Position> {
    if form.focus.is_parent() {
        return None;
    }
    let inner = Block::default().borders(Borders::ALL).inner(area);
    if inner.width == 0 || inner.height == 0 {
        return None;
    }
    let row = form.focus.index() as u16;
    if row >= inner.height {
        return None;
    }
    // The same prefix the row renderer writes: focus marker, label, colon, space.
    // Measured on the rendered spans rather than by character count, so a value
    // wider than it is long (any non-ASCII in a title) still lands the caret
    // correctly.
    let prefix = format!("> {}: ", form.focus.label());
    let column = Span::raw(prefix).width() + Span::raw(form.focused_value().to_string()).width();
    let column = u16::try_from(column).unwrap_or(u16::MAX);
    Some(Position::new(
        inner.x + column.min(inner.width - 1),
        inner.y + row,
    ))
}

/// Put the terminal's text cursor at the end of the focused field's value.
///
/// Until this existed, `set_cursor_position` was never called anywhere in the
/// crate: the cursor stayed wherever the previously rendered widget left it, and
/// the form showed no insertion point at all. "Create issue" opened on an empty
/// Title row that was underlined and nothing else, and characters appeared with the
/// caret parked elsewhere (#1486).
///
/// Called by the owner of the frame rather than from `render_with_bindings`,
/// because where the form is a **backdrop** — under the date-picker overlay — the
/// overlay owns the cursor and a caret on the row behind it would point at the
/// wrong surface.
pub fn place_caret(form: &FormState, f: &mut Frame, area: Rect) {
    if let Some(position) = caret_position(form, area) {
        f.set_cursor_position(position);
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn focus_cycles_forward() {
        assert_eq!(FormFocus::Title.next(), FormFocus::Status);
        assert_eq!(FormFocus::DueDate.next(), FormFocus::Parent);
        assert_eq!(FormFocus::Parent.next(), FormFocus::Title);
    }

    #[test]
    fn focus_cycles_backward() {
        assert_eq!(FormFocus::Title.prev(), FormFocus::Parent);
        assert_eq!(FormFocus::Status.prev(), FormFocus::Title);
    }

    /// `next`, `prev`, and `RING` are three statements of the same order, and the
    /// compiler cannot check that they agree — an out-of-date arm compiles and
    /// silently sends the cursor to the wrong field.
    ///
    /// Asserted as a walk over the ring rather than as a list of pairs, so adding a
    /// field cannot leave the pairs stale: the test has to be updated to pass, and
    /// updating it means reading the ring.
    #[test]
    fn the_ring_and_the_next_prev_chains_agree() {
        let ring = FormFocus::RING;
        for (i, focus) in ring.iter().enumerate() {
            let forward = ring[(i + 1) % ring.len()];
            let backward = ring[(i + ring.len() - 1) % ring.len()];
            assert_eq!(focus.next(), forward, "next() after {focus:?} in RING");
            assert_eq!(focus.prev(), backward, "prev() after {focus:?} in RING");
        }
    }

    /// `RING` must contain every variant, or a field becomes unreachable: there is
    /// no way to tab onto it and no way off whatever precedes it. `index()` panics
    /// on a variant missing from `RING`, so this is that panic's guard, as a test.
    #[test]
    fn the_ring_covers_every_field() {
        for (i, focus) in FormFocus::RING.iter().enumerate() {
            assert_eq!(focus.index(), i, "{focus:?} must sit at its RING position");
        }
        // And a fresh form starts on a field that is in the ring.
        assert!(FormFocus::RING.contains(&FormState::new("todo").focus));
    }

    /// The parent field is chosen from a picker, so typing into it must do nothing.
    /// A half-typed number is not a parent, and the service validates by resolved
    /// number — free text here could only ever be a value that fails at submit.
    #[test]
    fn the_parent_field_refuses_typed_characters() {
        let mut form = FormState::new("todo");
        form.move_focus_next();
        for _ in 0..FormFocus::RING.len() {
            if form.focus == FormFocus::Parent {
                break;
            }
            form.move_focus_next();
        }
        assert_eq!(form.focus, FormFocus::Parent, "the ring must reach Parent");
        assert!(form.focus.is_picker_only());
        assert!(!form.focus.is_date(), "Parent is picker-only, not a date");

        form.insert_char('9');
        form.insert_char('x');
        form.delete_char();
        assert_eq!(form.parent, "", "typing must not reach the parent field");
        assert_eq!(form.focused_value(), "");

        // But a *picked* value does, and it reads back through the same accessor.
        form.parent = "42".to_string();
        assert_eq!(form.focused_value(), "42");
    }

    #[test]
    fn form_insert_and_delete() {
        let mut form = FormState::new("todo");
        form.insert_char('h');
        form.insert_char('i');
        assert_eq!(form.title, "hi");
        form.delete_char();
        assert_eq!(form.title, "h");
    }

    #[test]
    fn form_move_focus() {
        let mut form = FormState::new("todo");
        assert_eq!(form.focus, FormFocus::Title);
        form.move_focus_next();
        assert_eq!(form.focus, FormFocus::Status);
        form.move_focus_prev();
        assert_eq!(form.focus, FormFocus::Title);
    }

    #[test]
    fn render_smoke() {
        use ratatui::Terminal;
        use ratatui::backend::TestBackend;

        let backend = TestBackend::new(80, 16);
        let mut terminal = Terminal::new(backend).unwrap();
        let form = FormState::new("todo");
        terminal.draw(|f| render(&form, f, f.area())).unwrap();

        let buf = terminal.backend().buffer();
        let mut text = String::new();
        for y in 0..buf.area.height {
            for x in 0..buf.area.width {
                text.push_str(buf[(x, y)].symbol());
            }
            text.push('\n');
        }
        assert!(text.contains("F2: Date"), "got {text:?}");
    }

    /// The regression from #1486: with nothing drawn over it, rendering the create
    /// form leaves the terminal cursor **on the focused row**. Before this,
    /// `set_cursor_position` was called nowhere in the crate, so the cursor stayed
    /// wherever the previous frame put it and the form showed no insertion point.
    #[test]
    fn rendering_the_create_form_puts_the_caret_on_the_title_row() {
        use ratatui::Terminal;
        use ratatui::backend::TestBackend;

        let mut terminal = Terminal::new(TestBackend::new(60, 16)).unwrap();
        let form = FormState::new("todo");
        terminal.draw(|f| render(&form, f, f.area())).unwrap();

        // The block's border puts the inner area at (1, 1); the row prefix for an
        // empty title is "> Title: ".
        assert_eq!(
            terminal.backend().cursor_position(),
            Position::new(1 + "> Title: ".len() as u16, 1)
        );
    }

    #[test]
    fn caret_follows_the_typed_value() {
        let area = Rect::new(10, 5, 40, 20);
        let mut form = FormState::new("todo");
        form.title = "abc".to_string();
        assert_eq!(
            caret_position(&form, area),
            // inner starts one cell inside the border, at (11, 6).
            Some(Position::new(11 + "> Title: abc".len() as u16, 6))
        );
    }

    #[test]
    fn caret_moves_with_the_focused_row() {
        let area = Rect::new(0, 0, 40, 20);
        let mut form = FormState::new("todo");
        form.move_focus_next();
        assert_eq!(
            caret_position(&form, area),
            // Row 1 of the ring, and the inner area already starts one row down.
            Some(Position::new(1 + "> Status: todo".len() as u16, 2))
        );
    }

    /// Width is not length: a two-character title occupies four cells, and the caret
    /// follows the cells.
    #[test]
    fn caret_measures_display_width_not_char_count() {
        let area = Rect::new(0, 0, 40, 20);
        let mut form = FormState::new("todo");
        form.title = "中日".to_string();
        assert_eq!(
            caret_position(&form, area),
            Some(Position::new(1 + "> Title: ".len() as u16 + 4, 1))
        );
    }

    /// A value wider than the field is clipped, so its true caret is off-screen; the
    /// position must stay inside the row rather than point past the border.
    #[test]
    fn caret_is_clamped_into_the_visible_row() {
        let area = Rect::new(0, 0, 20, 20);
        let mut form = FormState::new("todo");
        form.title = "x".repeat(100);
        // Inner width is 18, so the row's last cell is x = 18.
        assert_eq!(caret_position(&form, area), Some(Position::new(18, 1)));
    }

    #[test]
    fn no_caret_on_a_picker_only_field() {
        let area = Rect::new(0, 0, 40, 20);
        let mut form = FormState::new("todo");
        form.focus = FormFocus::Parent;
        assert_eq!(caret_position(&form, area), None);
    }

    #[test]
    fn caret_is_not_placed_outside_the_visible_form() {
        // Four rows: the ring's later fields are below the fold and get no caret,
        // because a position outside the rendered area would be drawn nowhere.
        let area = Rect::new(0, 0, 40, 4);
        let mut form = FormState::new("todo");
        form.focus = FormFocus::Reviewer;
        assert_eq!(caret_position(&form, area), None);
    }

    #[test]
    fn with_default_assignee_populates_assignee_field() {
        let form = FormState::with_default_assignee("in progress", "alice");
        assert_eq!(form.assignee, "alice");
        assert_eq!(form.status, "in progress");
        assert_eq!(form.focus, FormFocus::Title);
    }
}