tix-tracker 0.12.0

//! The `F8` Schedule page: the **Series** tab (tix #1593, mission
//! `recurring-issues-01M3C7G7` WP07) and the **Cycle schedules** tab (mission
//! `repeating-cycle-schedules-01M3C7W1` WP07, tix #181).
//!
//! # What the page is for
//!
//! The due warning ([`crate::ui::recurring_warning`]) answers "something is due —
//! what now?" once. This page is where the series *live*: their identity, rule,
//! lifecycle state, cursor and skipped dates, and the keys that act on them. It is
//! a top-level mode like `F4`/`F5`/`F6`, not a modal, so the board's own state is
//! not borrowed while a user manages a schedule.
//!
//! # Three tabs
//!
//! `F8` Schedule holds three tabs — Series (#175), Cycle schedules (#181, this one)
//! and Capacity (#182, WP06 of mission `cycle-capacity-planning-01M3C85C`). Series
//! ships with the recurring-issues mission, Cycle schedules with #181 and Capacity
//! with the cycle-capacity mission; the strip draws exactly the tabs that exist
//! rather than pretending others do.
//!
//! All three tabs are *renderers*: the page owns no registry, no evaluator and no
//! generator. Every value comes from [`crate::app::App`], which reads the one
//! service each figure belongs to — so a tab and `tix recurring …`/
//! `tix cycle schedule …`/`tix capacity …` cannot disagree (C-008/NFR-003), and the
//! page can hold no second evaluator, cursor or History grammar. The one thing the
//! page *does* define is the two **forms** that collect a record's fields —
//! [`ScheduleForm`] for a cycle schedule and [`SeriesForm`] for a recurring series —
//! and each submit is the shared service's: the cycle registry's
//! [`create`](crate::cycle_schedule::registry::create)/
//! [`edit`](crate::cycle_schedule::registry::edit) — which the CLI's `--confirm` and
//! the MCP tools also reach — and `tix recurring create`'s own `create_series`,
//! which the CLI and this page's form share (no MCP tool creates a series).
//!
//! # The Capacity tab renders what the CLI exposes
//!
//! Each row is one configured scope ([`CapacityRow`]): the resolved display label
//! `tix capacity list` prints, beside the shared calculation's compact values and
//! unit. The detail pane carries the **same fields `tix capacity calculate` prints**
//! (`print_calculation`'s order, verbatim), each finding through the shared
//! [`crate::capacity::warning::CapacityWarning::render`] — its reason and its remedy
//! — and, for a cycle scope, the immutable close evidence `tix capacity snapshot`
//! reads back, labelled historical beside the live values (T033). Nothing is
//! recomputed here: every number is a field of [`crate::capacity::calculate::CapacityCalculation`]
//! or [`crate::capacity::snapshot::CapacitySnapshot`], and an absent value prints `-`
//! rather than `0`.
//!
//! # The Cycle schedules tab renders what the CLI exposes
//!
//! Each schedule row carries the fields `tix cycle schedule list` prints; the detail
//! pane carries the values `tix cycle schedule show` prints (identity, cadence,
//! duration, start date, timezone, look-ahead and the derived cursor), the schedule's
//! generated cycles (`id`, `sequence`, `name`, dates, `state`), its closed snapshots
//! (`docs/cycle_snapshots/…`) and the findings [`crate::cycle_schedule::identity`]
//! reported — plus the warnings `tix cycle schedule detect` evaluates. Nothing is a
//! TUI-only number, and both empty states say how to stop being empty.
//!
//! # The keys act through the shared services
//!
//! Series tab: `n` defines a series (the same `tix recurring create` the CLI runs),
//! `p`ause / `r`esume / `x` end change lifecycle state; `g`enerate,
//! `s`kip, `d`efer and `i`gnore act on the series' **due candidate** as the shared
//! detector reports it. Cycle schedules tab: `n` defines a schedule and `E`
//! (`e`xtend owns the lowercase) edits the selected one through the form; `g`enerate
//! runs WP04's confirmed generator; `p`ause/`r`esume/adjust-future (`a`)/`i`gnore act
//! on the schedule, and `c`lose / `e`xtend / `s`kip act on its current instance —
//! each as a WP05 confirmed lifecycle request. The four actions that record a reason
//! collect one first, and every outcome is the service's own word
//! (`created`/`no-op`/`rejected`, `applied`/`no-op`/`rejected`) rather than a private
//! success/failure notion. A series or schedule with nothing to act on says so instead
//! of inventing a target, and no answer is ever a refresh effect (C-003/C-004).
//!
//! `Tab`/`Shift+Tab` switch tabs. They are read raw by the page (the page's
//! `[schedule]` table binds the Series actions), exactly as the
//! Portfolio page's Roadmap tab reads its own command letters raw — and for the same
//! reason `E`, `c`, `R`, `e` and `a` on the Cycle schedules tab are.

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

use crate::app::App;
use crate::cycle_schedule::config::CycleScheduleId;
use crate::cycle_schedule::identity::GeneratedCycleId;
use crate::cycle_schedule::lifecycle::LifecycleAction;
use crate::keybindings::TuiAction;

/// Which tab of the page is showing.
///
/// A `const ALL` in display order, like the Library and Portfolio pages' tabs: the
/// strip, the hint line, the cursor clamp and the empty state all read this list,
/// so a further tab (Capacity, #182) is additive here and nowhere else.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash)]
pub enum ScheduleTab {
    /// The recurring series (mission `recurring-issues-01M3C7G7`, #175).
    #[default]
    Series,
    /// The configured cycle schedules and the cycles they generated (#181).
    Cycles,
    /// The configured capacity scopes and their shared calculations (mission
    /// `cycle-capacity-planning-01M3C85C`, WP06, #182).
    Capacity,
}

impl ScheduleTab {
    /// The tabs in display order.
    pub const ALL: [Self; 3] = [Self::Series, Self::Cycles, Self::Capacity];

    /// The tab's label in the strip.
    pub const fn label(self) -> &'static str {
        match self {
            Self::Series => "Series",
            Self::Cycles => "Cycle schedules",
            Self::Capacity => "Capacity",
        }
    }

    /// The next tab, wrapping. `Tab` moves forward.
    pub const fn next(self) -> Self {
        match self {
            Self::Series => Self::Cycles,
            Self::Cycles => Self::Capacity,
            Self::Capacity => Self::Series,
        }
    }

    /// The previous tab, wrapping. `Shift+Tab` moves backward.
    ///
    /// Spelled out rather than delegated to [`Self::next`]: with three tabs `next`
    /// and `prev` are no longer inverses of one another, so sharing one body would
    /// make `Shift+Tab` step forward.
    pub const fn prev(self) -> Self {
        match self {
            Self::Series => Self::Capacity,
            Self::Cycles => Self::Series,
            Self::Capacity => Self::Cycles,
        }
    }

    /// The keys this tab answers to, as its hint line.
    pub const fn hint(self) -> &'static str {
        match self {
            Self::Series => SERIES_KEYS,
            Self::Cycles => CYCLE_SCHEDULE_KEYS,
            Self::Capacity => CAPACITY_KEYS,
        }
    }

    /// What the tab says when there is nothing to show, including how to fill it.
    ///
    /// Kept here rather than in the app so the sentence is a property of the page a
    /// test can assert, not a string literal inside a render function.
    pub const fn empty_hint(self) -> &'static str {
        match self {
            Self::Series => {
                "No recurring series yet. Create one with \
                 `tix recurring create --title <TITLE> --rule daily --anchor <DATE>`, \
                 or press `n` to create one here."
            }
            Self::Cycles => {
                "No cycle schedules yet. Create one with `tix cycle schedule create --id <ID> \
                 --name <NAME> --cadence <KIND> --duration <N> --duration-unit <UNIT> \
                 --start-date <DATE> --timezone <TZ> --confirm`."
            }
            Self::Capacity => {
                "No capacity configured. Configure one with `tix capacity set --scope \
                 <cycle|team|assignee> --id <REFERENCE> --value <N> --unit <UNIT>`."
            }
        }
    }
}

/// The page's own state: which tab is showing, which row the cursor is on, the reason
/// prompt when one is open, and the create/edit form when one is.
///
/// Session-only: nothing here is persisted, and the page owns no value the services
/// do not already own.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct ScheduleState {
    /// The tab in view.
    pub tab: ScheduleTab,
    /// The selected row within the active tab.
    pub selected: usize,
    /// The reason prompt, `Some` exactly while the page is collecting the reason a
    /// lifecycle action records (T037).
    pub prompt: Option<CycleReasonPrompt>,
    /// The create/edit form, `Some` exactly while the page is defining a schedule
    /// (T036).
    pub form: Option<ScheduleForm>,
    /// The Series tab's create form, `Some` exactly while the page is defining a
    /// recurring series.
    ///
    /// A **separate** field from [`Self::form`] rather than a variant of it: the two
    /// forms collect different fields (`title`/`rule`/`anchor` against the ten cycle
    /// schedule fields) and submit to different services, and one `Option` per form
    /// is what makes "which tab defined what" a property of the state rather than
    /// something a render has to infer.
    pub series_form: Option<SeriesForm>,
}

impl ScheduleState {
    /// A fresh page, on the first tab with the cursor on the first row.
    pub fn new() -> Self {
        Self::default()
    }

    /// Move the cursor by `delta`, clamped to `rows` entries.
    pub fn move_selected(&mut self, delta: isize, rows: usize) -> bool {
        let last = rows.saturating_sub(1);
        let before = self.selected;
        let next = if delta.is_negative() {
            self.selected.saturating_sub(delta.unsigned_abs())
        } else {
            self.selected.saturating_add(delta as usize)
        };
        self.selected = next.min(last);
        self.selected != before
    }

    /// Clamp the cursor into `rows` entries, for a registry that changed under the
    /// page.
    pub fn clamp_selected(&mut self, rows: usize) {
        self.selected = self.selected.min(rows.saturating_sub(1));
    }

    /// Step to the next (`delta` ≥ 0) or previous tab, wrapping, and reset the row
    /// cursor: it indexes the *active* tab's rows, so it must not carry over.
    pub fn switch_tab(&mut self, delta: isize) {
        self.tab = if delta.is_negative() {
            self.tab.prev()
        } else {
            self.tab.next()
        };
        self.selected = 0;
    }
}

/// One row of the Series tab, as display data: the widget never reads a registry.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ScheduleEntry {
    /// The series' display name.
    pub title: String,
    /// Its stable id, rule, state and cursor, as one dimmed tail.
    pub subtitle: String,
    /// Whether the series is currently due (its candidate has arrived).
    pub due: bool,
}

/// One row of the **Cycle schedules** tab, as display data.
///
/// The twin of [`ScheduleEntry`] for the other tab; the widget still reads nothing.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct CycleScheduleEntry {
    /// The schedule's display name.
    pub title: String,
    /// Its stable id, state, cadence, anchor and generated count, as one dimmed tail.
    pub subtitle: String,
    /// Whether the last evaluation reported a warning for it.
    pub warned: bool,
}

/// The `key: value` lines of the Series tab's detail pane, plus its heading.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct ScheduleDetail {
    /// The heading, e.g. `Series`.
    pub heading: String,
    /// The lines, in a stable order.
    pub lines: Vec<(String, String)>,
}

/// The Cycle schedules tab's detail pane: the schedule's own fields, then its
/// generated cycles, closed snapshots, identity findings and evaluated warnings.
///
/// Every section is a list of already-rendered lines, so the widget composes text
/// and computes nothing — the same rule the Series tab's [`ScheduleDetail`] follows.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct CycleScheduleDetail {
    /// The schedule record's own `key: value` facts.
    pub fields: Vec<(String, String)>,
    /// One line per generated cycle.
    pub cycles: Vec<String>,
    /// One line per closed snapshot.
    pub snapshots: Vec<String>,
    /// One line per identity finding.
    pub findings: Vec<String>,
    /// One line per evaluated warning.
    pub warnings: Vec<String>,
}

/// One row of the **Capacity** tab, as display data (WP06 T030/T032).
///
/// Every figure it names is a field of the shared [`crate::capacity::calculate::CapacityCalculation`],
/// already formatted by the caller: the widget composes text and computes nothing, the
/// same rule the page's other tabs follow.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct CapacityRow {
    /// The scope's resolved display label — **which scope the figures belong to**, the
    /// same `display` `tix capacity list`/`calculate` print.
    pub title: String,
    /// The compact `key: value` tail: the scope kind, the state, the values and the
    /// unit, with an absent value as `-` (never `0`).
    pub subtitle: String,
    /// Whether the calculation carried any finding (an overflow, an uncountable
    /// estimate, an unresolved reference).
    pub warned: bool,
    /// Whether the scope's committed work exceeds its ceiling
    /// ([`crate::capacity::calculate::CapacityCalculation::is_over_capacity`]).
    pub overflowing: bool,
}

/// A closed cycle's immutable capacity evidence, as the Capacity tab's detail draws it
/// (WP06 T033).
///
/// The `label` is the explicit **current-vs-historical** statement; the fields are the
/// ones `tix capacity snapshot <CYCLE>` prints, in that command's order.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct CapacitySnapshotView {
    /// The current-vs-historical label, and whether the cycle has been reopened or
    /// edited since the close.
    pub label: String,
    /// The stored evidence's own fields, exactly as the close wrote them.
    pub fields: Vec<(String, String)>,
}

/// The Capacity tab's detail pane (WP06 T030/T033): the selected scope's shared
/// calculation, its findings with their remedies, and — for a cycle scope with a closed
/// snapshot — the immutable close evidence beside the live values.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct CapacityDetail {
    /// The pane's heading: the scope's resolved display label.
    pub heading: String,
    /// The calculation's own fields, in `tix capacity calculate`'s order.
    pub fields: Vec<(String, String)>,
    /// Each finding, rendered through [`crate::capacity::warning::CapacityWarning::render`]
    /// — its reason **and** its remedy, one string per line.
    pub diagnostics: Vec<String>,
    /// The immutable close evidence, `Some` exactly when the scope is a cycle with a
    /// recorded snapshot.
    pub snapshot: Option<CapacitySnapshotView>,
}

/// The capacity read the page renders (WP06): the configured scopes' rows and their
/// details, plus the compact per-cycle cells the board's cycle group headers show.
///
/// Built once per refresh by [`crate::app::App`] from the **shared** DTOs — the same
/// one-pass pair and the same `for_scope` the CLI's `tix capacity calculate` calls — so
/// no value here is a TUI-only number (C-007/NFR-003).
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct CapacityView {
    /// One row per configured scope, in declaration order.
    pub rows: Vec<CapacityRow>,
    /// The selected row's detail, by the same index as [`Self::rows`].
    pub details: Vec<CapacityDetail>,
    /// A compact cell per cycle scope, keyed by the reference a card names **and** by
    /// the scope's resolved display label, for the board's grouped-by-cycle headers.
    pub summaries: std::collections::BTreeMap<String, String>,
}

/// The reason a lifecycle action records, being typed.
///
/// The action and its target are captured when the prompt opens, so confirming it
/// cannot drift onto another row: the prompt carries the schedule and the instance
/// it is about.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct CycleReasonPrompt {
    /// The schedule the action names.
    pub schedule: CycleScheduleId,
    /// The action that records the reason.
    pub action: LifecycleAction,
    /// The instance the action names, when it names one.
    pub cycle: Option<GeneratedCycleId>,
    /// The reason being typed.
    pub buffer: String,
}

/// One row of the `create`/`edit` form (T036).
///
/// The spellings are the CLI's: the form collects text and the shared registry parses
/// it, so "is `fortnightly` a cadence family" has one answer for every surface.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum ScheduleField {
    /// The stable id; the registry key, and create-only.
    Id,
    /// The display label.
    Name,
    /// The cadence family.
    Cadence,
    /// How many cadence units between starts.
    Interval,
    /// The unit an `interval` cadence counts in.
    Unit,
    /// How long one cycle lasts.
    Duration,
    /// The duration's unit.
    DurationUnit,
    /// The anchor date.
    StartDate,
    /// The fixed UTC offset.
    Timezone,
    /// How many future cycles to consider.
    LookAhead,
}

impl ScheduleField {
    /// Every field, in the form's row order.
    pub const ALL: [Self; 10] = [
        Self::Id,
        Self::Name,
        Self::Cadence,
        Self::Interval,
        Self::Unit,
        Self::Duration,
        Self::DurationUnit,
        Self::StartDate,
        Self::Timezone,
        Self::LookAhead,
    ];

    /// The fields an **edit** shows: everything but the identity, which is the
    /// registry key and does not change — a rename is a new `name`, not a new id.
    pub const EDIT: [Self; 9] = [
        Self::Name,
        Self::Cadence,
        Self::Interval,
        Self::Unit,
        Self::Duration,
        Self::DurationUnit,
        Self::StartDate,
        Self::Timezone,
        Self::LookAhead,
    ];

    /// The row's label.
    pub const fn label(self) -> &'static str {
        match self {
            Self::Id => "id",
            Self::Name => "name",
            Self::Cadence => "cadence",
            Self::Interval => "interval",
            Self::Unit => "unit",
            Self::Duration => "duration",
            Self::DurationUnit => "duration-unit",
            Self::StartDate => "start-date",
            Self::Timezone => "timezone",
            Self::LookAhead => "look-ahead",
        }
    }

    /// What the field accepts, shown beside it. The spellings are the contract's.
    pub const fn hint(self) -> &'static str {
        match self {
            Self::Id => "stable, never reused",
            Self::Name => "display label",
            Self::Cadence => "daily | weekly | monthly | interval",
            Self::Interval => "1-1000 (interval cadence)",
            Self::Unit => "days | weeks | months",
            Self::Duration => "positive count",
            Self::DurationUnit => "days | weeks | months",
            Self::StartDate => "YYYY-MM-DD",
            Self::Timezone => "UTC or ±HH:MM",
            Self::LookAhead => "future cycles to consider",
        }
    }

    /// Whether the field carries a calendar date, for the hint's sake.
    pub const fn is_date(self) -> bool {
        matches!(self, Self::StartDate)
    }
}

/// The `create`/`edit` form the Cycle schedules tab shows (T036).
///
/// A **page-local** form: the page owns it, exactly as it owns the reason prompt, so
/// defining a schedule needs no new mode, no new `InputContext` and no new binding.
/// It collects text and nothing else — every rule about what the text may be is the
/// shared registry's, and a refusal keeps the form open with the message on it rather
/// than closing and losing what was typed.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ScheduleForm {
    /// The id being edited, or `None` when the form creates a new schedule.
    pub editing: Option<String>,
    /// The fields shown, in row order.
    pub fields: Vec<ScheduleField>,
    /// The typed value per shown field, in the same order.
    pub values: Vec<String>,
    /// The focused row.
    pub focus: usize,
    /// The refusal the last save produced, kept while the form stays open.
    pub error: Option<String>,
}

impl ScheduleForm {
    /// A form that creates a schedule: every field empty, the id focused first.
    pub fn create() -> Self {
        let fields = ScheduleField::ALL.to_vec();
        let values = vec![String::new(); fields.len()];
        Self {
            editing: None,
            fields,
            values,
            focus: 0,
            error: None,
        }
    }

    /// A form that edits `id`, pre-filled from `values` (in [`ScheduleField::EDIT`]
    /// order).
    ///
    /// A short or long `values` is tolerated rather than panicking: the form is a
    /// session value a test can build by hand, and a missing value is an empty field.
    pub fn edit(id: String, values: Vec<String>) -> Self {
        let fields = ScheduleField::EDIT.to_vec();
        let mut filled = values;
        filled.resize(fields.len(), String::new());
        Self {
            editing: Some(id),
            fields,
            values: filled,
            focus: 0,
            error: None,
        }
    }

    /// The form's block title: what it is about to do, and to what.
    pub fn title(&self) -> String {
        match &self.editing {
            Some(id) => format!("Edit cycle schedule `{id}` (enter: save, esc: cancel)"),
            None => "New cycle schedule (enter: save, esc: cancel)".to_string(),
        }
    }

    /// The focused field.
    pub fn focused(&self) -> ScheduleField {
        self.fields
            .get(self.focus)
            .copied()
            .unwrap_or(ScheduleField::Id)
    }

    /// The typed value of `field` (`""` when the form does not show it).
    pub fn value(&self, field: ScheduleField) -> &str {
        self.fields
            .iter()
            .position(|shown| *shown == field)
            .and_then(|index| self.values.get(index))
            .map(String::as_str)
            .unwrap_or("")
    }

    /// Step the focus forward, wrapping.
    pub fn focus_next(&mut self) {
        let len = self.fields.len().max(1);
        self.focus = (self.focus + 1) % len;
    }

    /// Step the focus backward, wrapping.
    pub fn focus_prev(&mut self) {
        let len = self.fields.len().max(1);
        self.focus = (self.focus + len - 1) % len;
    }

    /// Append a character to the focused field.
    pub fn insert_char(&mut self, c: char) {
        let focus = self.focus;
        if let Some(value) = self.values.get_mut(focus) {
            value.push(c);
        }
    }

    /// Remove the focused field's last character.
    pub fn delete_char(&mut self) {
        let focus = self.focus;
        if let Some(value) = self.values.get_mut(focus) {
            value.pop();
        }
    }

    /// Empty the focused field, for a value being replaced rather than extended.
    pub fn clear_field(&mut self) {
        let focus = self.focus;
        if let Some(value) = self.values.get_mut(focus) {
            value.clear();
        }
    }

    /// Keep the refusal on the form, so the message and what was typed stay together.
    pub fn set_error(&mut self, message: String) {
        self.error = Some(message);
    }
}

/// One row of the Series tab's create form.
///
/// The spellings are the CLI's: the form collects text and the shared create service
/// parses it, so "is `fortnightly` a rule family" has one answer for every surface.
/// Only the three fields a first series cannot do without are collected — the issue's
/// `--body`/`--status`/`--priority`/… keep their CLI defaults, and `--name` defaults
/// to the title, exactly as `tix recurring create` leaves them.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum SeriesField {
    /// The series issue's title (and the default display name).
    Title,
    /// The rule family: what `--rule` accepts.
    Rule,
    /// The schedule origin, `YYYY-MM-DD`.
    Anchor,
}

impl SeriesField {
    /// Every field, in the form's row order.
    pub const ALL: [Self; 3] = [Self::Title, Self::Rule, Self::Anchor];

    /// The row's label.
    pub const fn label(self) -> &'static str {
        match self {
            Self::Title => "title",
            Self::Rule => "rule",
            Self::Anchor => "anchor",
        }
    }

    /// What the field accepts, shown beside it. The spellings are the contract's.
    ///
    /// The rule hint names only the families the form's three fields can complete:
    /// `interval` needs a count and a unit and `cron-like` needs an expression, so
    /// offering them here would advertise a choice the form always refuses. They are
    /// named in [`SeriesForm::NOTE`] as the CLI's, not the form's.
    pub const fn hint(self) -> &'static str {
        match self {
            Self::Title => "issue title (required)",
            Self::Rule => "daily | weekly | monthly",
            Self::Anchor => "YYYY-MM-DD",
        }
    }
}

/// The Series tab's create form.
///
/// A **page-local** form, the twin of [`ScheduleForm`]: the page owns it, so defining
/// a series needs no new mode, no new `InputContext` and no new binding. It collects
/// text and nothing else — every rule about what the text may be is the shared create
/// service's, and a refusal keeps the form open with the message on it rather than
/// closing and losing what was typed.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct SeriesForm {
    /// The fields shown, in row order.
    pub fields: Vec<SeriesField>,
    /// The typed value per shown field, in the same order.
    pub values: Vec<String>,
    /// The focused row.
    pub focus: usize,
    /// The refusal the last save produced, kept while the form stays open.
    pub error: Option<String>,
}

impl SeriesForm {
    /// Where the rule families the form cannot express are defined.
    ///
    /// The three fields complete `daily`, `weekly` and `monthly`. The other two
    /// families need arguments the form does not collect, so rather than offer them
    /// (and refuse), the form says where they live — the same service, the CLI's own
    /// flags. Asserted against [`SeriesField::Rule::hint`] by a test, so the two can
    /// not drift apart again.
    pub const NOTE: &'static str = "`interval` and `cron-like` rules need the CLI: \
                                    `tix recurring create --rule <FAMILY> --interval \
                                    <N> --unit <UNIT>`.";

    /// A form that creates a series: every field empty, the title focused first.
    pub fn create() -> Self {
        Self {
            fields: SeriesField::ALL.to_vec(),
            values: vec![String::new(); SeriesField::ALL.len()],
            focus: 0,
            error: None,
        }
    }

    /// The form's block title: what it is about to do, and the keys it answers to.
    pub fn title(&self) -> &'static str {
        "New recurring series (enter: save, esc: cancel)"
    }

    /// The focused field.
    pub fn focused(&self) -> SeriesField {
        self.fields
            .get(self.focus)
            .copied()
            .unwrap_or(SeriesField::Title)
    }

    /// The typed value of `field` (`""` when the form does not show it).
    pub fn value(&self, field: SeriesField) -> &str {
        self.fields
            .iter()
            .position(|shown| *shown == field)
            .and_then(|index| self.values.get(index))
            .map(String::as_str)
            .unwrap_or("")
    }

    /// Step the focus forward, wrapping.
    pub fn focus_next(&mut self) {
        let len = self.fields.len().max(1);
        self.focus = (self.focus + 1) % len;
    }

    /// Step the focus backward, wrapping.
    pub fn focus_prev(&mut self) {
        let len = self.fields.len().max(1);
        self.focus = (self.focus + len - 1) % len;
    }

    /// Append a character to the focused field.
    pub fn insert_char(&mut self, c: char) {
        let focus = self.focus;
        if let Some(value) = self.values.get_mut(focus) {
            value.push(c);
        }
    }

    /// Remove the focused field's last character.
    pub fn delete_char(&mut self) {
        let focus = self.focus;
        if let Some(value) = self.values.get_mut(focus) {
            value.pop();
        }
    }

    /// Empty the focused field, for a value being replaced rather than extended.
    pub fn clear_field(&mut self) {
        let focus = self.focus;
        if let Some(value) = self.values.get_mut(focus) {
            value.clear();
        }
    }

    /// Keep the refusal on the form, so the message and what was typed stay together.
    pub fn set_error(&mut self, message: String) {
        self.error = Some(message);
    }
}

/// The rows the `?` overlay shows on the **Cycle schedules** tab, as
/// `(action, description)` for the keys the page's binding section binds.
///
/// The Series tab is served by the keybinding table's own list and its own wording.
/// This tab needs its own: the same letters act on the *schedules* rather than on a
/// series, two bound Series keys (`x` end, `d` defer) have no meaning here and must
/// not be advertised as if they did, and four of the tab's keys are read raw. Keeping
/// the list here is what stops the overlay and the tab from describing different keys.
pub const CYCLE_HELP_ACTIONS: &[(TuiAction, &str)] = &[
    (TuiAction::MoveUp, "move the cursor up"),
    (TuiAction::MoveDown, "move the cursor down"),
    (
        TuiAction::SeriesGenerate,
        "generate the schedule's look-ahead",
    ),
    (TuiAction::SeriesSkip, "skip the current cycle"),
    (TuiAction::SeriesPause, "pause the schedule"),
    (TuiAction::SeriesResume, "resume the schedule"),
    (
        TuiAction::SeriesIgnore,
        "close a warning without deciding anything",
    ),
    (TuiAction::Help, "this help"),
    (TuiAction::Close, "back to the board"),
];

/// The keys the Cycle schedules tab answers to that **no** [`TuiAction`] names,
/// because the page reads them raw: `(key, description)`.
pub const CYCLE_HELP_RAW: &[(&str, &str)] = &[
    ("tab / shift+tab", "switch tabs"),
    ("n", "define a new schedule"),
    ("E", "edit the selected schedule"),
    ("c", "close the current cycle (asks why)"),
    ("R", "reopen the closed cycle (asks why)"),
    ("e", "extend the current cycle (asks why)"),
    ("s", "skip the current cycle (asks why)"),
    ("a", "re-derive future cycles (asks why)"),
];

/// The keys the **Series** tab answers to, as its hint line.
pub const SERIES_KEYS: &str = "j/k: move  n: new  g: generate  p: pause  r: resume  x: end  \
                               s: skip  d: defer  i: ignore  q: back to the board";

/// The Series tab's hint, kept under its original name.
pub const SCHEDULE_KEYS: &str = SERIES_KEYS;

/// The keys the **Cycle schedules** tab answers to, as its hint line.
pub const CYCLE_SCHEDULE_KEYS: &str = "j/k: move  Tab: tabs  n: new  E: edit  g: generate  \
                                       c: close  R: reopen  e: extend  s: skip  p: pause  \
                                       r: resume  a: adjust-future  i: ignore  q: back to the board";

/// The keys the **Capacity** tab answers to, as its hint line.
///
/// The tab is read-only: it shows the shared calculation and acts on nothing, so
/// `j`/`k`, the tab switch and the way back are all it names.
pub const CAPACITY_KEYS: &str = "j/k: move  Tab: tabs  q: back to the board";

/// The rows the `?` overlay shows on the **Capacity** tab.
///
/// Like the Cycle schedules tab, the tab has its own row set rather than the Series
/// tab's: `g`enerate, `p`ause and the rest act on a series and mean nothing on this
/// tab, so advertising them here would name keys that do nothing.
pub const CAPACITY_HELP_ACTIONS: &[(TuiAction, &str)] = &[
    (TuiAction::MoveUp, "move the cursor up"),
    (TuiAction::MoveDown, "move the cursor down"),
    (TuiAction::Help, "this help"),
    (TuiAction::Close, "back to the board"),
];

/// The keys the Capacity tab answers to that **no** [`TuiAction`] names, because the
/// page reads them raw: `(key, description)`.
pub const CAPACITY_HELP_RAW: &[(&str, &str)] = &[("tab / shift+tab", "switch tabs")];

fn dim() -> Style {
    Style::default().fg(Color::DarkGray)
}

/// The tab strip: the page's name and every tab, the active one cyan and bold.
fn tab_line(active: ScheduleTab) -> Line<'static> {
    let mut spans = vec![
        Span::styled("F8 Schedule", Style::default().add_modifier(Modifier::BOLD)),
        Span::raw("  "),
    ];
    for (index, tab) in ScheduleTab::ALL.iter().enumerate() {
        if index > 0 {
            spans.push(Span::raw("  "));
        }
        let style = if *tab == active {
            Style::default()
                .fg(Color::Cyan)
                .add_modifier(Modifier::BOLD)
        } else {
            dim()
        };
        spans.push(Span::styled(format!("[{}]", tab.label()), style));
    }
    Line::from(spans)
}

/// The rect of every tab in the strip, in display order (WP06).
///
/// The strip is drawn by [`tab_line`] on the page's first row; this mirrors that
/// line's own widths so a pointer click can address a tab. Kept beside the renderer
/// so the two cannot drift: a label or a separator changed in one changes both.
pub fn tab_rects(area: Rect) -> Vec<(ScheduleTab, Rect)> {
    use unicode_width::UnicodeWidthStr;

    // The page's name, then the two-space gap before the first tab.
    let mut x = area.x + UnicodeWidthStr::width("F8 Schedule") as u16 + 2;
    let mut rects = Vec::with_capacity(ScheduleTab::ALL.len());
    for (index, tab) in ScheduleTab::ALL.iter().enumerate() {
        if index > 0 {
            x += 2;
        }
        let label = format!("[{}]", tab.label());
        let width = UnicodeWidthStr::width(label.as_str()) as u16;
        rects.push((*tab, Rect::new(x, area.y, width, 1)));
        x += width;
    }
    rects
}

/// The reason prompt's line: what is being decided, and what is being typed.
fn prompt_line(prompt: &CycleReasonPrompt) -> Line<'static> {
    let mut spans = vec![Span::styled(
        prompt.action.as_str().to_string(),
        Style::default().add_modifier(Modifier::BOLD),
    )];
    if let Some(cycle) = &prompt.cycle {
        spans.push(Span::raw(format!(" {cycle}")));
    }
    spans.push(Span::styled("  reason> ", dim()));
    spans.push(Span::raw(prompt.buffer.clone()));
    spans.push(Span::styled(
        "  (enter: apply  esc: cancel, nothing written)",
        dim(),
    ));
    Line::from(spans)
}

/// Draw the page: strip and hints, then the active tab's body.
pub fn render(app: &App, f: &mut Frame, area: Rect) {
    let state = app.schedule_state();

    let rows = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Length(1),
            Constraint::Length(1),
            Constraint::Min(1),
        ])
        .split(area);
    f.render_widget(Paragraph::new(tab_line(state.tab)), rows[0]);
    // A reason prompt owns the hint row: the line under the strip is the page's one
    // status line, and what the user is typing has to be visible on it. Otherwise a
    // refusal or confirmation raised by an action is shown here rather than being
    // written into `status_msg` where only the board could render it.
    match state.prompt.as_ref() {
        Some(prompt) => f.render_widget(Paragraph::new(prompt_line(prompt)), rows[1]),
        None if app.status_msg.is_some() => {
            let message = app.status_msg.as_deref().unwrap_or_default();
            f.render_widget(
                Paragraph::new(Span::styled(message, Style::default())),
                rows[1],
            );
        }
        None => f.render_widget(
            Paragraph::new(Span::styled(state.tab.hint(), dim())),
            rows[1],
        ),
    }

    // The create/edit form takes the whole body: it is the page's only mode that is
    // about one record rather than a list, and a half-drawn list beside it would
    // invite the page's other keys while they are inert (the form owns every key).
    // Only one of the two forms can be open — each `n` opens the one its tab owns.
    if let Some(form) = state.series_form.as_ref() {
        render_series_form(form, f, rows[2]);
        return;
    }
    if let Some(form) = state.form.as_ref() {
        render_form(form, f, rows[2]);
        return;
    }

    match state.tab {
        ScheduleTab::Series => render_series(app, f, rows[2], &state),
        ScheduleTab::Cycles => render_cycles(app, f, rows[2], &state),
        ScheduleTab::Capacity => render_capacity(app, f, rows[2], &state),
    }
}

/// The create/edit form: one row per field, the focused one marked and highlighted,
/// the keys and the last refusal under it.
///
/// It draws no value the page does not hold: the fields and the text are the state's,
/// and the refusal is the shared registry's own rendered block.
fn render_form(form: &ScheduleForm, f: &mut Frame, area: Rect) {
    let rows: Vec<(String, String, String)> = form
        .fields
        .iter()
        .map(|field| {
            (
                field.label().to_string(),
                form.value(*field).to_string(),
                field.hint().to_string(),
            )
        })
        .collect();
    render_form_fields(
        f,
        area,
        &form.title(),
        &rows,
        form.focus,
        form.error.as_deref(),
        None,
    );
}

/// The Series tab's create form: the same shape as [`render_form`], its own fields.
fn render_series_form(form: &SeriesForm, f: &mut Frame, area: Rect) {
    let rows: Vec<(String, String, String)> = form
        .fields
        .iter()
        .map(|field| {
            (
                field.label().to_string(),
                form.value(*field).to_string(),
                field.hint().to_string(),
            )
        })
        .collect();
    render_form_fields(
        f,
        area,
        form.title(),
        &rows,
        form.focus,
        form.error.as_deref(),
        Some(SeriesForm::NOTE),
    );
}

/// Draw a form body: `(label, value, hint)` per row, the focused one marked and
/// highlighted, the field keys and the last refusal under it.
///
/// One renderer for both the Cycle schedules form and the Series form, so a form key
/// hint or a refusal block cannot drift between the page's two tabs.
fn render_form_fields(
    f: &mut Frame,
    area: Rect,
    title: &str,
    rows: &[(String, String, String)],
    focus: usize,
    error: Option<&str>,
    note: Option<&str>,
) {
    let block = Block::default()
        .borders(Borders::ALL)
        .title(title.to_string());
    let inner = block.inner(area);
    f.render_widget(block, area);

    let mut lines: Vec<Line<'static>> = Vec::new();
    for (index, (label, value, hint)) in rows.iter().enumerate() {
        let focused = index == focus;
        let mut spans = vec![Span::raw(if focused { "> " } else { "  " })];
        spans.push(Span::styled(
            format!("{label}: "),
            if focused {
                Style::default().add_modifier(Modifier::BOLD)
            } else {
                dim()
            },
        ));
        spans.push(Span::raw(value.clone()));
        if focused {
            spans.push(Span::styled("▏", Style::default().fg(Color::Cyan)));
        }
        spans.push(Span::styled(format!("  ({hint})"), dim()));
        lines.push(Line::from(spans));
    }
    lines.push(Line::from(""));
    if let Some(note) = note {
        lines.push(Line::from(Span::styled(note.to_string(), dim())));
        lines.push(Line::from(""));
    }
    lines.push(Line::from(Span::styled(
        "tab / shift+tab: field  enter: save  esc: cancel, nothing written",
        dim(),
    )));
    if let Some(error) = error {
        lines.push(Line::from(""));
        for line in error.lines() {
            lines.push(Line::from(Span::styled(
                line.to_string(),
                Style::default().fg(Color::Red),
            )));
        }
    }
    f.render_widget(Paragraph::new(lines).wrap(Wrap { trim: false }), inner);
}

/// The Series tab: the list of series beside the selected one's detail.
fn render_series(app: &App, f: &mut Frame, area: Rect, state: &ScheduleState) {
    let entries = app.schedule_entries();
    let detail = app.schedule_detail(state.selected);

    let body = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([Constraint::Percentage(45), Constraint::Min(24)])
        .split(area);

    let list = Block::default()
        .borders(Borders::ALL)
        .title(format!("Series ({})", entries.len()));
    if entries.is_empty() {
        f.render_widget(
            Paragraph::new(ScheduleTab::Series.empty_hint())
                .block(list)
                .wrap(Wrap { trim: true })
                .style(dim()),
            body[0],
        );
    } else {
        let mut lines: Vec<Line<'static>> = Vec::new();
        for (index, entry) in entries.iter().enumerate() {
            let selected = index == state.selected;
            let mut spans = vec![Span::raw(if selected { "> " } else { "  " })];
            spans.push(Span::styled(
                entry.title.clone(),
                if selected {
                    Style::default().add_modifier(Modifier::BOLD)
                } else {
                    Style::default()
                },
            ));
            if entry.due {
                spans.push(Span::styled("  [due]", Style::default().fg(Color::Cyan)));
            }
            lines.push(Line::from(spans));
            lines.push(Line::from(Span::styled(
                format!("    {}", entry.subtitle),
                dim(),
            )));
        }
        f.render_widget(Paragraph::new(lines).block(list), body[0]);
    }

    let block = Block::default()
        .borders(Borders::ALL)
        .title("Series detail");
    match detail.as_ref() {
        Some(detail) => {
            let lines: Vec<Line<'static>> = detail
                .lines
                .iter()
                .map(|(key, value)| {
                    Line::from(vec![
                        Span::styled(format!("{key}: "), dim()),
                        Span::raw(value.clone()),
                    ])
                })
                .collect();
            f.render_widget(
                Paragraph::new(lines)
                    .block(block)
                    .wrap(Wrap { trim: false }),
                body[1],
            );
        }
        None => f.render_widget(
            Paragraph::new(Span::styled(
                "Nothing selected: a series has to exist before the page can describe it.",
                dim(),
            ))
            .block(block)
            .wrap(Wrap { trim: true }),
            body[1],
        ),
    }
}

/// The Cycle schedules tab: the schedule list (with any finding that belongs to no
/// listed schedule under it) beside the selected schedule's detail.
fn render_cycles(app: &App, f: &mut Frame, area: Rect, state: &ScheduleState) {
    let entries = app.cycle_schedule_entries();
    let detail = app.cycle_schedule_detail(state.selected);
    let unattached = app.cycle_schedule_unattached_findings();

    let body = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([Constraint::Percentage(45), Constraint::Min(24)])
        .split(area);

    // A dangling identity — a generated cycle naming a schedule that is not in the
    // registry — has no row of its own, so it gets its own block under the list
    // rather than being silently counted. Its height is the block it needs, capped
    // so a wall of findings cannot swallow the list.
    if unattached.is_empty() {
        render_cycle_list(f, body[0], &entries, state.selected);
    } else {
        // Two rows of chrome, plus three rows per finding: a rendered diagnostic is
        // one long sentence that wraps in a pane this narrow, and clipping it to a
        // single row would hide the half that says which schedule is missing. Capped
        // so a wall of findings cannot swallow the list.
        let height = (unattached.len() as u16 * 3 + 2).min(12);
        let columns = Layout::default()
            .direction(Direction::Vertical)
            .constraints([Constraint::Min(3), Constraint::Length(height)])
            .split(body[0]);
        render_cycle_list(f, columns[0], &entries, state.selected);
        let findings: Vec<Line<'static>> = unattached
            .iter()
            .map(|line| Line::from(Span::styled(line.clone(), dim())))
            .collect();
        f.render_widget(
            Paragraph::new(findings)
                .block(
                    Block::default()
                        .borders(Borders::ALL)
                        .title(format!("Unattached findings ({})", unattached.len())),
                )
                .wrap(Wrap { trim: true }),
            columns[1],
        );
    }

    let block = Block::default()
        .borders(Borders::ALL)
        .title("Cycle schedule detail");
    match detail.as_ref() {
        Some(detail) => {
            let mut lines: Vec<Line<'static>> = detail
                .fields
                .iter()
                .map(|(key, value)| {
                    Line::from(vec![
                        Span::styled(format!("{key}: "), dim()),
                        Span::raw(value.clone()),
                    ])
                })
                .collect();
            section(&mut lines, "cycles", &detail.cycles);
            section(&mut lines, "snapshots", &detail.snapshots);
            section(&mut lines, "findings", &detail.findings);
            section(&mut lines, "warnings", &detail.warnings);
            f.render_widget(
                Paragraph::new(lines)
                    .block(block)
                    .wrap(Wrap { trim: false }),
                body[1],
            );
        }
        None => f.render_widget(
            Paragraph::new(Span::styled(
                "Nothing selected: a cycle schedule has to exist before the page can \
                 describe it.",
                dim(),
            ))
            .block(block)
            .wrap(Wrap { trim: true }),
            body[1],
        ),
    }
}

/// The schedule list block, its empty state explicit.
fn render_cycle_list(f: &mut Frame, area: Rect, entries: &[CycleScheduleEntry], selected: usize) {
    let block = Block::default()
        .borders(Borders::ALL)
        .title(format!("Cycle schedules ({})", entries.len()));
    if entries.is_empty() {
        f.render_widget(
            Paragraph::new(ScheduleTab::Cycles.empty_hint())
                .block(block)
                .wrap(Wrap { trim: true })
                .style(dim()),
            area,
        );
        return;
    }
    let mut lines: Vec<Line<'static>> = Vec::new();
    for (index, entry) in entries.iter().enumerate() {
        let is_selected = index == selected;
        let mut spans = vec![Span::raw(if is_selected { "> " } else { "  " })];
        spans.push(Span::styled(
            entry.title.clone(),
            if is_selected {
                Style::default().add_modifier(Modifier::BOLD)
            } else {
                Style::default()
            },
        ));
        if entry.warned {
            spans.push(Span::styled("  [warn]", Style::default().fg(Color::Yellow)));
        }
        lines.push(Line::from(spans));
        lines.push(Line::from(Span::styled(
            format!("    {}", entry.subtitle),
            dim(),
        )));
    }
    f.render_widget(Paragraph::new(lines).block(block), area);
}

/// Append one `heading (N):` section and its lines — or an explicit `none`, so a
/// section can never be mistaken for a rendering failure.
fn section(lines: &mut Vec<Line<'static>>, heading: &str, body: &[String]) {
    lines.push(Line::from(""));
    lines.push(Line::from(Span::styled(
        format!("{heading} ({}):", body.len()),
        Style::default().add_modifier(Modifier::BOLD),
    )));
    if body.is_empty() {
        lines.push(Line::from(Span::styled("  none", dim())));
        return;
    }
    for line in body {
        lines.push(Line::from(Span::raw(format!("  {line}"))));
    }
}

/// The Capacity tab: the configured scopes beside the selected one's shared
/// calculation, its findings and — for a cycle scope — its immutable close evidence.
///
/// Read-only: it draws what [`crate::app::App`] read from the shared DTOs and offers
/// no key that writes. Its empty state is a sentence — both when nothing is
/// configured and when nothing is committed — so a blank pane can never be mistaken
/// for a rendering failure; and a **failed** read is distinguished from an empty
/// selection in both panes, so neither can claim nothing is configured while the
/// question was never answered.
fn render_capacity(app: &App, f: &mut Frame, area: Rect, state: &ScheduleState) {
    let rows = app.capacity_rows();
    let body = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([Constraint::Percentage(45), Constraint::Min(24)])
        .split(area);

    let list = Block::default()
        .borders(Borders::ALL)
        .title(format!("Capacity ({})", rows.len()));
    if !app.capacity_read() {
        f.render_widget(
            Paragraph::new(
                "Could not read the capacity snapshot for this project, so no capacity view \
                 is available.",
            )
            .block(list)
            .wrap(Wrap { trim: true })
            .style(dim()),
            body[0],
        );
    } else if rows.is_empty() {
        f.render_widget(
            Paragraph::new(ScheduleTab::Capacity.empty_hint())
                .block(list)
                .wrap(Wrap { trim: true })
                .style(dim()),
            body[0],
        );
    } else {
        let mut lines: Vec<Line<'static>> = Vec::new();
        for (index, row) in rows.iter().enumerate() {
            let selected = index == state.selected;
            let mut spans = vec![Span::raw(if selected { "> " } else { "  " })];
            spans.push(Span::styled(
                row.title.clone(),
                if selected {
                    Style::default().add_modifier(Modifier::BOLD)
                } else {
                    Style::default()
                },
            ));
            if row.overflowing {
                spans.push(Span::styled("  [over]", Style::default().fg(Color::Red)));
            } else if row.warned {
                spans.push(Span::styled("  [warn]", Style::default().fg(Color::Yellow)));
            }
            lines.push(Line::from(spans));
            lines.push(Line::from(Span::styled(
                format!("    {}", row.subtitle),
                dim(),
            )));
        }
        // "Nothing committed" is a fact about the work rather than about the
        // configuration, and a reader must not have to infer it from `-` values.
        if app.capacity_nothing_committed() {
            lines.push(Line::from(""));
            lines.push(Line::from(Span::styled(
                "no committed work in any configured scope yet",
                dim(),
            )));
        }
        f.render_widget(Paragraph::new(lines).block(list), body[0]);
    }

    let block = Block::default()
        .borders(Borders::ALL)
        .title("Capacity detail");
    match app.capacity_detail(state.selected) {
        Some(detail) => {
            let mut lines: Vec<Line<'static>> = Vec::new();
            for (key, value) in &detail.fields {
                lines.push(Line::from(vec![
                    Span::styled(format!("{key}: "), dim()),
                    Span::raw(value.clone()),
                ]));
            }
            section(&mut lines, "findings", &detail.diagnostics);
            if let Some(snapshot) = &detail.snapshot {
                lines.push(Line::from(""));
                lines.push(Line::from(Span::styled(
                    format!("closed snapshot — {}", snapshot.label),
                    Style::default().add_modifier(Modifier::BOLD),
                )));
                for (key, value) in &snapshot.fields {
                    lines.push(Line::from(vec![
                        Span::styled(format!("{key}: "), dim()),
                        Span::raw(value.clone()),
                    ]));
                }
                if snapshot.fields.is_empty() {
                    lines.push(Line::from(Span::styled("  none", dim())));
                }
            }
            f.render_widget(
                Paragraph::new(lines)
                    .block(block)
                    .wrap(Wrap { trim: false }),
                body[1],
            );
        }
        None => {
            // A missing detail has two causes, and they are not the same statement:
            // there is nothing selected, or the read that would have supplied the
            // rows failed. The list pane already distinguishes them; a detail pane
            // claiming "nothing is configured" over a failed read would be exactly the
            // conflation the mission's absent-value rules forbid.
            let sentence = if app.capacity_read() {
                "Nothing selected: a capacity scope has to be configured before the page \
                 can describe it."
            } else {
                "Could not read the capacity snapshot for this project, so no capacity \
                 view is available."
            };
            f.render_widget(
                Paragraph::new(Span::styled(sentence, dim()))
                    .block(block)
                    .wrap(Wrap { trim: true }),
                body[1],
            );
        }
    }
}

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

    #[test]
    fn the_cursor_clamps_to_the_row_count() {
        let mut state = ScheduleState::new();
        assert!(state.move_selected(3, 5));
        assert_eq!(state.selected, 3);
        assert!(state.move_selected(9, 5), "clamped to the last row");
        assert_eq!(state.selected, 4);
        assert!(!state.move_selected(1, 5));
        state.move_selected(-9, 5);
        assert_eq!(state.selected, 0);
        state.move_selected(1, 0);
        assert_eq!(state.selected, 0, "an empty list keeps the cursor at zero");
    }

    #[test]
    fn a_shrinking_registry_clamps_the_cursor() {
        let mut state = ScheduleState {
            selected: 4,
            ..Default::default()
        };
        state.clamp_selected(2);
        assert_eq!(state.selected, 1);
        state.clamp_selected(0);
        assert_eq!(state.selected, 0);
    }

    #[test]
    fn the_tab_strip_has_all_three_tabs_and_the_series_tab_is_the_default() {
        assert_eq!(ScheduleTab::default(), ScheduleTab::Series);
        assert_eq!(
            ScheduleTab::ALL,
            [
                ScheduleTab::Series,
                ScheduleTab::Cycles,
                ScheduleTab::Capacity
            ]
        );
        assert_eq!(ScheduleTab::Series.label(), "Series");
        assert_eq!(ScheduleTab::Cycles.label(), "Cycle schedules");
        assert_eq!(ScheduleTab::Capacity.label(), "Capacity");
        let drawn: String = tab_line(ScheduleTab::Capacity)
            .spans
            .iter()
            .map(|span| span.content.clone())
            .collect();
        assert!(drawn.contains("[Series]"), "{drawn}");
        assert!(drawn.contains("[Cycle schedules]"), "{drawn}");
        assert!(drawn.contains("[Capacity]"), "{drawn}");
        assert!(drawn.contains("F8 Schedule"), "{drawn}");
    }

    #[test]
    fn the_tab_strip_geometry_matches_the_drawn_line() {
        // The pointer addresses a tab by the rect this reports, so it must land on
        // the label the strip actually draws — a mismatch would make a click switch
        // to the wrong tab. Each rect's label is read back out of the same line.
        let area = Rect::new(3, 7, 80, 24);
        let drawn: Vec<String> = tab_line(ScheduleTab::Series)
            .spans
            .iter()
            .map(|span| span.content.to_string())
            .collect();
        let line = drawn.concat();
        let rects = tab_rects(area);
        assert_eq!(rects.len(), ScheduleTab::ALL.len());
        for (tab, rect) in rects {
            assert_eq!(rect.y, area.y, "the strip is one row at the top");
            assert_eq!(rect.height, 1);
            let start = usize::from(rect.x - area.x);
            let end = start + usize::from(rect.width);
            assert_eq!(
                &line[start..end],
                format!("[{}]", tab.label()),
                "the rect addresses {tab:?}'s own label"
            );
        }
    }

    #[test]
    fn switching_tabs_wraps_and_resets_the_row_cursor() {
        let mut state = ScheduleState {
            selected: 3,
            ..Default::default()
        };
        state.switch_tab(1);
        assert_eq!(state.tab, ScheduleTab::Cycles);
        assert_eq!(
            state.selected, 0,
            "the cursor indexes the active tab's rows"
        );
        state.switch_tab(1);
        assert_eq!(state.tab, ScheduleTab::Capacity);
        state.switch_tab(1);
        assert_eq!(state.tab, ScheduleTab::Series, "`Tab` wraps");
        state.switch_tab(-1);
        assert_eq!(state.tab, ScheduleTab::Capacity, "`Shift+Tab` steps back");
    }

    #[test]
    fn every_tab_has_an_explicit_empty_state() {
        for tab in ScheduleTab::ALL {
            assert!(
                tab.empty_hint().contains("No ") || tab.empty_hint().contains("yet"),
                "{tab:?} says what is missing: {}",
                tab.empty_hint()
            );
        }
    }

    #[test]
    fn the_series_empty_state_keeps_the_cli_hint_and_adds_the_tui_offer() {
        let hint = ScheduleTab::Series.empty_hint();
        assert!(
            hint.contains(
                "Create one with `tix recurring create --title <TITLE> --rule daily \
                 --anchor <DATE>`"
            ),
            "the CLI hint survives verbatim: {hint}"
        );
        assert!(
            hint.contains("press `n` to create one here"),
            "and the TUI offers its own key: {hint}"
        );
    }

    #[test]
    fn the_hint_line_advertises_every_key_the_series_tab_handles() {
        for expected in [
            "j/k",
            "n: new",
            "g: generate",
            "p: pause",
            "r: resume",
            "x: end",
            "s: skip",
            "d: defer",
            "i: ignore",
            "q: back",
        ] {
            assert!(
                SERIES_KEYS.contains(expected),
                "the page advertises `{expected}`: {SERIES_KEYS}"
            );
        }
    }

    #[test]
    fn the_cycle_tab_hint_advertises_every_key_it_handles() {
        for expected in [
            "j/k",
            "Tab: tabs",
            "n: new",
            "E: edit",
            "g: generate",
            "c: close",
            "e: extend",
            "s: skip",
            "p: pause",
            "r: resume",
            "a: adjust-future",
            "i: ignore",
            "q: back",
        ] {
            assert!(
                CYCLE_SCHEDULE_KEYS.contains(expected),
                "the tab advertises `{expected}`: {CYCLE_SCHEDULE_KEYS}"
            );
        }
    }

    #[test]
    fn the_cycle_help_rows_advertise_the_same_keys_as_the_hint() {
        // The `?` overlay and the page's own hint row are two instructions to the
        // same user; a key the tab acts on must be in both, or one of them lies.
        let advertised: Vec<&str> = CYCLE_HELP_RAW.iter().map(|(key, _)| *key).collect();
        for key in ["tab / shift+tab", "n", "E", "c", "e", "s", "a"] {
            assert!(
                advertised.contains(&key),
                "the help names `{key}`: {advertised:?}"
            );
        }
        // And the two rows the tab does not act on are gone.
        let actions: Vec<TuiAction> = CYCLE_HELP_ACTIONS.iter().map(|(a, _)| *a).collect();
        assert!(
            !actions.contains(&TuiAction::SeriesEnd),
            "`x` ends a series and means nothing here"
        );
        assert!(
            !actions.contains(&TuiAction::SeriesDefer),
            "`d` defers a series' due date and means nothing here"
        );
    }

    #[test]
    fn the_capacity_help_rows_advertise_the_same_keys_as_the_hint() {
        // The Capacity tab is read-only, so its overlay must name only the keys it
        // acts on: `j`/`k`, the tab switch and the way back. A series action here
        // would be an instruction that does nothing.
        let actions: Vec<TuiAction> = CAPACITY_HELP_ACTIONS.iter().map(|(a, _)| *a).collect();
        for action in [
            TuiAction::MoveUp,
            TuiAction::MoveDown,
            TuiAction::Help,
            TuiAction::Close,
        ] {
            assert!(
                actions.contains(&action),
                "the help names {action:?}: {actions:?}"
            );
        }
        for absent in [
            TuiAction::SeriesGenerate,
            TuiAction::SeriesPause,
            TuiAction::SeriesEnd,
        ] {
            assert!(
                !actions.contains(&absent),
                "{absent:?} acts on nothing here"
            );
        }
        assert!(CAPACITY_KEYS.contains("j/k"), "{CAPACITY_KEYS}");
        assert!(CAPACITY_KEYS.contains("Tab: tabs"), "{CAPACITY_KEYS}");
        assert!(CAPACITY_KEYS.contains("q: back"), "{CAPACITY_KEYS}");
        assert_eq!(
            CAPACITY_HELP_RAW
                .iter()
                .map(|(key, _)| *key)
                .collect::<Vec<_>>(),
            vec!["tab / shift+tab"]
        );
    }

    #[test]
    fn the_create_form_shows_every_field_and_the_edit_form_every_but_the_id() {
        let create = ScheduleForm::create();
        assert_eq!(create.fields, ScheduleField::ALL);
        assert_eq!(create.focused(), ScheduleField::Id);
        assert!(create.title().contains("New cycle schedule"));

        let edit = ScheduleForm::edit("cs-x".to_string(), vec!["Name".to_string()]);
        assert_eq!(edit.fields, ScheduleField::EDIT);
        assert!(
            !edit.fields.contains(&ScheduleField::Id),
            "the identity is the registry key and does not change"
        );
        assert_eq!(edit.value(ScheduleField::Name), "Name");
        assert_eq!(
            edit.value(ScheduleField::Id),
            "",
            "not shown by the edit form"
        );
        assert_eq!(
            edit.value(ScheduleField::StartDate),
            "",
            "a missing value is empty"
        );
        assert!(edit.title().contains("cs-x"));
    }

    #[test]
    fn the_form_focus_wraps_and_typing_lands_in_the_focused_field() {
        let mut form = ScheduleForm::create();
        form.insert_char('c');
        form.insert_char('s');
        assert_eq!(form.value(ScheduleField::Id), "cs");
        form.focus_next();
        assert_eq!(form.focused(), ScheduleField::Name);
        form.insert_char('X');
        assert_eq!(form.value(ScheduleField::Name), "X");
        form.delete_char();
        assert_eq!(form.value(ScheduleField::Name), "");
        form.focus_prev();
        assert_eq!(form.focused(), ScheduleField::Id, "backward wraps too");
        // Forward from the last field wraps to the first.
        for _ in 0..ScheduleField::ALL.len() {
            form.focus_next();
        }
        assert_eq!(form.focused(), ScheduleField::Id);

        // A refusal is kept on the form, so what was typed survives it.
        form.set_error("nope".to_string());
        assert_eq!(form.error.as_deref(), Some("nope"));
    }

    #[test]
    fn the_series_create_form_asks_for_the_three_required_fields() {
        let form = SeriesForm::create();
        assert_eq!(form.fields, SeriesField::ALL);
        assert_eq!(
            form.fields,
            [SeriesField::Title, SeriesField::Rule, SeriesField::Anchor],
            "the first-run path is title, rule, anchor — the three the CLI requires"
        );
        assert_eq!(form.focused(), SeriesField::Title);
        // Every field names the vocabulary it accepts, so the form is its own remedy.
        for field in SeriesField::ALL {
            assert!(!field.label().is_empty(), "{field:?} has a label");
            assert!(!field.hint().is_empty(), "{field:?} has a hint");
        }
        assert_eq!(
            SeriesField::Rule.hint(),
            "daily | weekly | monthly",
            "the rule hint names only the families the form's three fields can complete"
        );
        assert!(
            SeriesForm::NOTE.contains("`interval`")
                && SeriesForm::NOTE.contains("`cron-like`")
                && SeriesForm::NOTE.contains("tix recurring create"),
            "the families the form cannot complete are named as the CLI's: {}",
            SeriesForm::NOTE
        );
        assert_eq!(SeriesField::Anchor.hint(), "YYYY-MM-DD");
        assert!(form.title().contains("New recurring series"));
    }

    #[test]
    fn the_series_form_focus_wraps_and_typing_lands_in_the_focused_field() {
        let mut form = SeriesForm::create();
        for c in "Nightly".chars() {
            form.insert_char(c);
        }
        assert_eq!(form.value(SeriesField::Title), "Nightly");
        form.focus_next();
        assert_eq!(form.focused(), SeriesField::Rule);
        for c in "daily".chars() {
            form.insert_char(c);
        }
        assert_eq!(form.value(SeriesField::Rule), "daily");
        form.focus_next();
        form.insert_char('X');
        assert_eq!(form.value(SeriesField::Anchor), "X");
        form.delete_char();
        assert_eq!(form.value(SeriesField::Anchor), "");
        form.clear_field();
        assert_eq!(form.value(SeriesField::Anchor), "");
        form.focus_prev();
        assert_eq!(form.focused(), SeriesField::Rule, "backward wraps too");
        // Forward from the last field wraps to the first.
        form.focus_next(); // anchor
        form.focus_next(); // wraps back to the title
        assert_eq!(
            form.focused(),
            SeriesField::Title,
            "forward wraps to the first field"
        );
        for _ in 0..SeriesField::ALL.len() {
            form.focus_next();
        }
        assert_eq!(form.focused(), SeriesField::Title);

        form.set_error("refused".to_string());
        assert_eq!(form.error.as_deref(), Some("refused"));
        // A field the form does not show reads as empty rather than panicking.
        assert_eq!(form.value(SeriesField::Title), "Nightly");
    }
}