datui-lib 0.4.5

use crate::analysis::data_quality::{
    DataQualityPlan, DataQualityResults, IntervalClock, IntervalFact, QUALITY_WINDOW_WIDTHS,
    QualityComparison, QualityCompute, QualityGrain, QualityMetric, QualityPage, TIME_FORMATS,
    TemporalRole, TemporalRoleAssignment, TimeInterpretation, TimeKind,
};
use crate::analysis::quality_report::{EvidenceRows, Finding, FindingsView, QualityReport};
use crate::analysis::statistics::{AnalysisResults, DistributionType};
use ratatui::widgets::TableState;

/// The rows of Data Quality Setup, top to bottom: the rows read, what the columns
/// mean, and how the study splits and compares them.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SetupRow {
    Sample,
    TextAsTime,
    TimeRoles,
    Intervals,
    /// What columns must hold, declared: the key and each column's rules.
    Intent,
    Grain,
    Expected,
    Compare,
    Values,
    Latency,
    WindowBy,
}

impl SetupRow {
    pub const ALL: [Self; 11] = [
        Self::Sample,
        Self::TextAsTime,
        Self::TimeRoles,
        Self::Intervals,
        Self::Intent,
        Self::Grain,
        Self::Expected,
        Self::Compare,
        Self::Values,
        Self::Latency,
        Self::WindowBy,
    ];

    pub fn label(self) -> &'static str {
        match self {
            Self::Sample => "Sample",
            Self::TextAsTime => "Text as time",
            Self::TimeRoles => "Time roles",
            Self::Intervals => "Intervals",
            Self::Intent => "Column intent",
            Self::Grain => "Grain",
            Self::Expected => "Expected",
            Self::Compare => "Compare",
            Self::Values => "Values",
            Self::Latency => "Latency over",
            Self::WindowBy => "Window by",
        }
    }

    /// The row at `index`, the last one past the end.
    pub fn at(index: usize) -> Self {
        Self::ALL[index.min(Self::ALL.len() - 1)]
    }

    pub fn index(self) -> usize {
        Self::ALL.iter().position(|row| *row == self).unwrap_or(0)
    }
}

/// What a Setup row's picker sets.
#[derive(Debug, Clone, PartialEq)]
pub enum PlanChoice {
    Grain(QualityGrain),
    Values(QualityCompute),
    Compare(QualityComparison),
    Latency(Option<i64>),
    /// Which time puts an interval in a window.
    Clock(IntervalClock),
    /// A text column to read as time; choosing it asks for the format next.
    TextColumn(String),
    /// How a text column is read as time, or `None` to read it as text again.
    Format(String, Option<(TimeKind, &'static str)>),
    /// Only the findings that name this column, or all of them.
    FindingColumn(Option<String>),
    /// Only the findings this check made, or all of them.
    FindingCheck(Option<&'static str>),
}

impl PlanChoice {
    fn is_current(&self, plan: &DataQualityPlan) -> bool {
        match self {
            Self::Grain(grain) => &plan.grain == grain,
            Self::Values(QualityCompute::Metadata) => plan.compute == QualityCompute::Metadata,
            Self::Values(_) => plan.compute != QualityCompute::Metadata,
            Self::Compare(comparison) => &plan.comparison == comparison,
            Self::Latency(seconds) => &plan.latency_threshold_seconds == seconds,
            Self::Clock(clock) => plan.interval_clock == *clock,
            Self::TextColumn(column) => plan.time_format(column).is_some(),
            Self::Format(column, format) => {
                plan.time_format(column)
                    .map(|current| (current.kind, current.format.as_str()))
                    == format.map(|(kind, format)| (kind, format))
            }
            // The findings list is not the plan: its picker selects its own current.
            Self::FindingColumn(_) | Self::FindingCheck(_) => false,
        }
    }
}

/// A Setup row's choices, or the findings list's narrowing, open as a list.
#[derive(Debug, Clone)]
pub struct PlanPicker {
    pub title: String,
    pub choices: Vec<PlanChoice>,
    pub state: crate::widgets::ui::PickerState,
}

/// What the data offers Setup's choices: partition columns, time-window columns
/// (and whether they hold times of day), whether there are files to split by, and
/// text columns readable as time with a few values from the rows on screen.
#[derive(Debug, Clone, Default)]
pub struct PlanContext {
    pub partitions: Vec<String>,
    pub time_columns: Vec<(String, bool)>,
    pub files: bool,
    pub text_columns: Vec<(String, Vec<String>)>,
}

/// Rows a finding names that the run did not keep, waiting for Enter to read them.
/// Nothing reads until then, and Esc drops it.
#[derive(Debug, Clone)]
pub struct EvidenceRead {
    pub rows: EvidenceRows,
    /// The table's label once the rows are shown.
    pub label: String,
    /// Draw this sample again from its seed, rather than read the scope.
    pub sample: Option<crate::analysis::sampling::Sample>,
    /// The scope the rows are read from.
    pub scope: crate::analysis::data_quality::QualityScope,
    /// What the read is, as the dialog says it: label, value.
    pub summary: Vec<(&'static str, String)>,
}

/// A latency threshold as Setup offers it, or its length when it is none of those.
pub fn threshold_label(seconds: Option<i64>) -> String {
    match seconds {
        None => "none".to_string(),
        Some(3_600) => "1 hour".to_string(),
        Some(86_400) => "1 day".to_string(),
        Some(604_800) => "1 week".to_string(),
        Some(seconds) => crate::numfmt::duration(seconds),
    }
}

/// Which windows the Expected editor's first row says rows are expected in.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ExpectedCadence {
    /// None stated: no window is a gap.
    None,
    /// Every window of the grain.
    Every,
    /// Monday to Friday's hours or days.
    Weekdays,
}

/// The rows of the Expected editor.
pub const EXPECTED_ROWS: [&str; 3] = ["Windows", "From", "Before"];

/// The Expected editor while it is open: the cadence, and the range as typed. Its
/// Enter writes them into the draft, and its Esc leaves the draft as it was.
#[derive(Debug, Clone)]
pub struct ExpectedForm {
    /// The row under the cursor, in [`EXPECTED_ROWS`].
    pub field: usize,
    pub cadence: ExpectedCadence,
    pub from: crate::widgets::text_input::TextInput,
    pub before: crate::widgets::text_input::TextInput,
    /// Why Enter did not apply, until the next edit.
    pub error: Option<String>,
}

impl ExpectedForm {
    pub fn new(plan: &DataQualityPlan, theme: &crate::config::Theme) -> Self {
        let input = || crate::widgets::text_input::TextInput::new().with_theme(theme);
        let (mut from, mut before) = (input(), input());
        let cadence = match &plan.expected {
            None => ExpectedCadence::None,
            Some(expected) => {
                from.set_value(expected.from.as_deref().unwrap_or_default());
                before.set_value(expected.before.as_deref().unwrap_or_default());
                // Weekdays stated for days read as every window once the grain is
                // weeks or months, as Setup and the check read it.
                let every = match &plan.grain {
                    crate::analysis::data_quality::QualityGrain::TimeWindows { every, .. } => {
                        every.as_str()
                    }
                    _ => "",
                };
                if expected.weekdays
                    && crate::analysis::data_quality::ExpectedWindows::weekdays_apply(every)
                {
                    ExpectedCadence::Weekdays
                } else {
                    ExpectedCadence::Every
                }
            }
        };
        let mut form = Self {
            field: 0,
            cadence,
            from,
            before,
            error: None,
        };
        form.sync_focus();
        form
    }

    /// The choices the Windows row cycles through for windows `every` wide.
    pub fn cadences(every: &str) -> Vec<ExpectedCadence> {
        let mut cadences = vec![ExpectedCadence::None, ExpectedCadence::Every];
        if crate::analysis::data_quality::ExpectedWindows::weekdays_apply(every) {
            cadences.push(ExpectedCadence::Weekdays);
        }
        cadences
    }

    /// The cadence in the editor's words.
    pub fn cadence_label(&self, every: &str) -> String {
        match self.cadence {
            ExpectedCadence::None => "none: no window is a gap".to_string(),
            ExpectedCadence::Every => {
                crate::analysis::data_quality::ExpectedWindows::default().cadence_label(every)
            }
            ExpectedCadence::Weekdays => "weekdays, Monday to Friday".to_string(),
        }
    }

    pub fn cycle(&mut self, every: &str, forward: bool) {
        let cadences = Self::cadences(every);
        let at = cadences
            .iter()
            .position(|cadence| *cadence == self.cadence)
            .unwrap_or(0);
        let next = if forward {
            (at + 1) % cadences.len()
        } else {
            (at + cadences.len() - 1) % cadences.len()
        };
        self.cadence = cadences[next];
        self.error = None;
    }

    /// Whether the row under the cursor is one typed into.
    pub fn typing(&self) -> bool {
        self.field > 0
    }

    pub fn input_mut(&mut self) -> Option<&mut crate::widgets::text_input::TextInput> {
        match self.field {
            1 => Some(&mut self.from),
            2 => Some(&mut self.before),
            _ => None,
        }
    }

    pub fn sync_focus(&mut self) {
        self.from.set_focused(self.field == 1);
        self.before.set_focused(self.field == 2);
    }

    /// What the editor states, or why it cannot be read.
    pub fn expected(
        &self,
    ) -> Result<Option<crate::analysis::data_quality::ExpectedWindows>, String> {
        if self.cadence == ExpectedCadence::None {
            return Ok(None);
        }
        let typed = |input: &crate::widgets::text_input::TextInput| {
            let text = input.value().trim();
            (!text.is_empty()).then(|| text.to_string())
        };
        let expected = crate::analysis::data_quality::ExpectedWindows {
            weekdays: self.cadence == ExpectedCadence::Weekdays,
            from: typed(&self.from),
            before: typed(&self.before),
        };
        match expected.problem() {
            Some(problem) => Err(problem),
            None => Ok(Some(expected)),
        }
    }
}

impl crate::app::form::Form for ExpectedForm {
    /// The row, in [`EXPECTED_ROWS`].
    type Field = usize;

    fn fields(&self) -> Vec<(usize, crate::app::form::FieldKind)> {
        use crate::app::form::FieldKind;
        (0..EXPECTED_ROWS.len())
            .map(|row| {
                let kind = if row == 0 {
                    FieldKind::Choice
                } else {
                    FieldKind::Text
                };
                (row, kind)
            })
            .collect()
    }

    fn focused(&self) -> usize {
        self.field
    }

    fn set_focused(&mut self, field: usize) {
        self.field = field;
        self.sync_focus();
    }
}

/// Read `column` as time through `format`, or as text again with `None`; a time
/// window on a column back to text falls back to the whole-dataset grain.
pub fn set_time_format(plan: &mut DataQualityPlan, column: &str, format: Option<(TimeKind, &str)>) {
    plan.time_formats
        .retain(|interpretation| interpretation.column != column);
    match format {
        Some((kind, format)) => plan.time_formats.push(TimeInterpretation {
            column: column.to_string(),
            kind,
            format: format.to_string(),
        }),
        None => {
            if matches!(&plan.grain, QualityGrain::TimeWindows { column: on, .. } if on == column) {
                plan.grain = QualityGrain::Dataset;
                plan.baseline_segment = None;
            }
        }
    }
}

#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub enum AnalysisView {
    #[default]
    Main, // Main tool view
    DistributionDetail, // Full-screen distribution detail view
    CorrelationDetail,  // Full-screen correlation pair detail view
}

#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub enum AnalysisTool {
    #[default]
    Describe, // Column describe table
    DistributionAnalysis, // Distribution analysis table
    CorrelationMatrix,    // Correlation matrix
    DataQuality,          // Multi-scale quality profile
}

impl AnalysisTool {
    /// The tools in the order the sidebar lists them.
    pub const ALL: [Self; 4] = [
        Self::Describe,
        Self::DistributionAnalysis,
        Self::CorrelationMatrix,
        Self::DataQuality,
    ];

    /// The tool's row in the sidebar.
    pub fn index(self) -> usize {
        Self::ALL.iter().position(|tool| *tool == self).unwrap_or(0)
    }
}

/// Progress state for the analysis progress overlay (display only).
#[derive(Debug, Clone)]
pub struct AnalysisProgress {
    pub phase: String,
    /// When the run began, for the elapsed time: a run has no total, so time is its
    /// progress.
    pub started: std::time::Instant,
    /// Whether the running stage reads the source or rows already read; `None` until
    /// a Data Quality run names its first stage.
    pub reads_source: Option<bool>,
    /// Whether a cancel stops the running stage partway; `None` until a Data Quality run
    /// names its first stage.
    pub interruptible: Option<bool>,
    /// The sampler's count of rows seen, where the read can count them.
    pub read: Option<crate::analysis::sampling::ReadWatch>,
    /// What the run starts from, when it reuses something: said before it starts.
    pub reuse: Option<String>,
}

impl AnalysisProgress {
    pub fn new(phase: &str) -> Self {
        Self {
            phase: phase.to_string(),
            started: std::time::Instant::now(),
            reads_source: None,
            interruptible: None,
            read: None,
            reuse: None,
        }
    }

    /// The stage now running reads the source in one collect nothing can stop: a
    /// cancel waits for its end.
    pub fn read_runs_out(&self) -> bool {
        self.reads_source == Some(true) && self.interruptible == Some(false)
    }
}

#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub enum AnalysisFocus {
    #[default]
    Main, // Focus on main area (tool view)
    Sidebar,              // Focus on sidebar (tool list)
    DistributionSelector, // Focus on distribution selector in detail view
}

/// A popup taller than the screen scrolls: the offset, and the most it can be.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub struct DetailScroll {
    pub offset: u16,
    pub max: u16,
}

/// Scrolling of a result table wider than its pane, by statistic: the first shown,
/// and `max`, set by the table as it draws, where the last comes into view.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub struct ColumnScroll {
    pub offset: usize,
    pub max: usize,
}

impl ColumnScroll {
    pub fn left(&mut self) {
        self.offset = self.offset.min(self.max).saturating_sub(1);
    }

    pub fn right(&mut self) {
        if self.offset < self.max {
            self.offset += 1;
        }
    }
}

#[derive(Default)]
pub struct AnalysisModal {
    pub scroll_position: usize,
    pub selected_column: Option<usize>,
    pub describe_columns: ColumnScroll,
    pub distribution_columns: ColumnScroll,
    /// Kept on the selected cell by the matrix as it draws.
    pub correlation_columns: ColumnScroll,
    /// The rows every tool reads (one scope, method, size and seed), so tools compare
    /// like with like. Kept across opens; `s` edits it.
    pub sample: crate::analysis::sampling::Sample,
    /// The dataset the sample's scope was chosen for: a partition or file scope means
    /// nothing on another.
    pub sample_dataset: Option<u64>,
    /// The dataset a sample last ran on; after that, a tool with no result runs at once
    /// instead of asking with the Sample form.
    pub sample_run_for: Option<u64>,
    /// The Sample form, while it is open.
    pub sample_form: Option<crate::analysis::sample_modal::SampleForm>,
    /// The tools' own sample, set aside while the view has its own sample, which every
    /// tool then reads whole.
    pub own_sample: Option<crate::analysis::sampling::Sample>,
    pub table_state: TableState,              // For describe table
    pub distribution_table_state: TableState, // For distribution table
    pub correlation_table_state: TableState,  // For correlation matrix
    pub sidebar_state: TableState,            // For sidebar tool list
    /// Cached results per tool; each tool computes and stores its own state independently.
    pub describe_results: Option<AnalysisResults>,
    pub distribution_results: Option<AnalysisResults>,
    pub correlation_results: Option<AnalysisResults>,
    /// Set while a tool runs: its phase and progress, drawn in place of results.
    pub computing: Option<AnalysisProgress>,
    pub view: AnalysisView,
    pub focus: AnalysisFocus,
    /// None = no tool selected yet (show instructions); Some(tool) = user chose a tool (may be computing or showing results).
    pub selected_tool: Option<AnalysisTool>,
    pub selected_distribution: Option<usize>, // Selected row in distribution table
    pub selected_correlation: Option<(usize, usize)>, // Selected cell in correlation matrix (row, col)
    /// The coefficient the matrix and the pair detail show; both are computed.
    pub correlation_method: crate::analysis::statistics::CorrelationMethod,
    pub selected_theoretical_distribution: DistributionType, // Selected theoretical distribution for Q-Q plot
    pub distribution_selector_state: TableState,             // For distribution selector list
    pub histogram_scale: HistogramScale,
    /// Data Quality: its plan, its report and where the cursor is in each.
    pub quality: QualityState, // Scale for histogram (linear or log)
    /// The view (`DataTableState::len_generation`) the results are of.
    pub results_view: Option<u64>,
    /// The results and positions a close put down, restored by the next open on the
    /// same view.
    kept: Option<Kept>,
}

/// Data Quality's part of the analysis modal: the plan, Setup's draft and its
/// editors, the report and where the cursor stands on each of its pages.
#[derive(Default)]
pub struct QualityState {
    pub results: Option<DataQualityResults>,
    pub page: QualityPage,
    /// The plan the last Run committed; while Setup is open, the draft for the next.
    pub plan: DataQualityPlan,
    /// The plan when Setup opened, restored by Esc; `None` while Setup is closed.
    pub setup_before: Option<DataQualityPlan>,
    /// The report page Setup was opened from, and goes back to.
    pub setup_return: QualityPage,
    /// Why Enter did not run, said on Setup's own line until the next edit.
    pub setup_note: Option<String>,
    pub table_state: TableState,
    /// The list a Setup row's choices open in, while it is open.
    pub picker: Option<PlanPicker>,
    /// The Setup row under the cursor, or the role in the time roles editor.
    pub plan_field: usize,
    pub show_access: bool,
    pub observation_detail: bool,
    /// Where the finding popup is scrolled to, and how far it can go (set as it draws).
    pub detail_scroll: DetailScroll,
    /// The segment a drill-in shows, and the one Segments selects on the way back.
    pub segment_index: usize,
    /// Segments listed clearest change first rather than in their own order.
    pub segments_by_change: bool,
    /// The clean entry's popup lists every check rather than the most important.
    pub checks_expanded: bool,
    pub plan_before_edit: Option<DataQualityPlan>,
    pub last_plan: Option<DataQualityPlan>,
    pub from_cache: bool,
    pub metric: QualityMetric,
    pub column_index: usize,
    /// The interval a detail shows, and the one Intervals selects on the way back.
    pub interval_index: usize,
    /// How Overview narrows and orders its findings; the report is not measured again.
    pub findings: FindingsView,
    /// A read for a finding's rows, shown with what it reads until Enter or Esc.
    pub evidence_read: Option<EvidenceRead>,
    /// The Trends line a bar detail shows, and the one Trends selects on the way back.
    pub trend_line: usize,
    /// The Expected editor, while it is open.
    pub expected_form: Option<ExpectedForm>,
    /// One column's declared intent, being edited over the Column intent list.
    pub intent_form: Option<crate::analysis::intent_modal::IntentForm>,
    /// The dialog that writes the report on screen to a file.
    pub export: Option<crate::analysis::quality_export::ExportForm>,
}

impl QualityState {
    /// A new dataset is on screen: findings narrowed to the last one's columns would
    /// hide this one's, and a read for its rows was over the last one.
    pub(crate) fn reset_for_dataset(&mut self) {
        self.findings = FindingsView::default();
        self.evidence_read = None;
    }

    /// What a close leaves: the plan, and how Segments is ordered.
    fn close(&mut self) {
        *self = Self {
            plan: std::mem::take(&mut self.plan),
            segments_by_change: self.segments_by_change,
            ..Self::default()
        };
    }
}

/// The tools' results as a close left them, and the cursor in each.
struct Kept {
    view: Option<u64>,
    tool: Option<AnalysisTool>,
    describe: Option<AnalysisResults>,
    distribution: Option<AnalysisResults>,
    correlation: Option<AnalysisResults>,
    row: Option<usize>,
    distribution_row: Option<usize>,
    cell: Option<(usize, usize)>,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum HistogramScale {
    #[default]
    Linear,
    Log,
}

impl AnalysisModal {
    /// A modal whose shared sample starts at the configured size: `[performance]
    /// analysis_sample_rows`, where 0 means every row.
    pub fn with_sample_rows(rows: usize) -> Self {
        let mut modal = Self::default();
        modal.sample.seed = crate::analysis::sample_modal::new_seed();
        if rows == 0 {
            modal.sample.method = crate::analysis::sampling::SampleMethod::EveryRow;
        } else {
            modal.sample.rows = rows;
        }
        modal
    }

    /// Open the screen on `view`: a close's results on this view come back as they
    /// were; on any other view every tool starts empty.
    pub fn open(&mut self, view: Option<u64>) {
        let kept = self
            .kept
            .take()
            .filter(|kept| view.is_some() && kept.view == view);
        self.results_view = view;
        self.scroll_position = 0;
        self.selected_column = None;
        self.describe_columns = ColumnScroll::default();
        self.distribution_columns = ColumnScroll::default();
        self.correlation_columns = ColumnScroll::default();
        self.table_state.select(Some(0));
        self.distribution_table_state.select(Some(0));
        self.correlation_table_state.select(Some(0));
        self.sidebar_state.select(Some(0)); // Highlight first tool; user must press Enter to select
        self.view = AnalysisView::Main;
        self.focus = AnalysisFocus::Sidebar; // Sidebar focused by default when no tool selected
        self.selected_tool = None; // No tool until user selects from sidebar
        self.selected_distribution = Some(0);
        self.selected_correlation = None;
        self.computing = None;
        self.describe_results = None;
        self.distribution_results = None;
        self.correlation_results = None;
        self.quality.close();
        self.sample_form = None;
        if let Some(kept) = kept {
            self.describe_results = kept.describe;
            self.distribution_results = kept.distribution;
            self.correlation_results = kept.correlation;
            self.selected_tool = kept.tool;
            if self.current_results().is_none() {
                self.selected_tool = None;
            }
            if let Some(tool) = self.selected_tool {
                self.sidebar_state.select(Some(tool.index()));
            }
            self.table_state.select(kept.row.or(Some(0)));
            self.distribution_table_state
                .select(kept.distribution_row.or(Some(0)));
            self.selected_distribution = kept.distribution_row.or(Some(0));
            if let Some(cell) = kept.cell {
                self.selected_correlation = Some(cell);
                self.correlation_table_state.select(Some(cell.0));
            }
        }
        if self.correlation_results.is_none() {
            self.selected_correlation = None;
        }
    }

    /// Close the screen, keeping the results for the next open on the same view.
    pub fn close(&mut self) {
        self.kept = Some(Kept {
            view: self.results_view.take(),
            tool: self
                .selected_tool
                .filter(|tool| *tool != AnalysisTool::DataQuality),
            describe: self.describe_results.take(),
            distribution: self.distribution_results.take(),
            correlation: self.correlation_results.take(),
            row: self.table_state.selected(),
            distribution_row: self.distribution_table_state.selected(),
            cell: self.selected_correlation,
        });
        self.scroll_position = 0;
        self.selected_column = None;
        self.describe_columns = ColumnScroll::default();
        self.distribution_columns = ColumnScroll::default();
        self.correlation_columns = ColumnScroll::default();
        self.view = AnalysisView::Main;
        self.focus = AnalysisFocus::Main;
        self.selected_tool = None;
        self.selected_distribution = None;
        self.selected_correlation = None;
        self.computing = None;
        self.describe_results = None;
        self.distribution_results = None;
        self.correlation_results = None;
        self.quality.results = None;
        self.quality.page = QualityPage::Setup;
        self.quality.setup_before = None;
        self.quality.setup_note = None;
        self.quality.picker = None;
        self.quality.show_access = false;
        self.quality.observation_detail = false;
        self.quality.plan_before_edit = None;
        self.quality.last_plan = None;
        self.quality.from_cache = false;
        self.quality.metric = QualityMetric::NullRate;
        self.quality.column_index = 0;
        self.quality.interval_index = 0;
        self.quality.trend_line = 0;
        self.quality.expected_form = None;
        self.quality.intent_form = None;
        self.quality.export = None;
    }

    /// Returns the cached results for the currently selected tool, if any.
    pub fn current_results(&self) -> Option<&AnalysisResults> {
        match self.selected_tool {
            Some(AnalysisTool::Describe) => self.describe_results.as_ref(),
            Some(AnalysisTool::DistributionAnalysis) => self.distribution_results.as_ref(),
            Some(AnalysisTool::CorrelationMatrix) => self.correlation_results.as_ref(),
            Some(AnalysisTool::DataQuality) => None,
            None => None,
        }
    }

    /// Tab on the main view: the tool list and the result trade focus. Not offered on
    /// detail views (one focusable thing) or before a tool is chosen.
    pub fn switch_focus(&mut self) {
        self.focus = match self.focus {
            AnalysisFocus::Sidebar if self.selected_tool.is_some() => AnalysisFocus::Main,
            _ => AnalysisFocus::Sidebar,
        };
    }

    /// The tool under the sidebar cursor.
    pub fn highlighted_tool(&self) -> Option<AnalysisTool> {
        AnalysisTool::ALL
            .get(self.sidebar_state.selected()?)
            .copied()
    }

    /// Select the tool under the sidebar cursor; the caller places the cursor.
    pub fn select_tool(&mut self) {
        if self.sidebar_state.selected().is_some() {
            self.selected_tool = Some(self.highlighted_tool().unwrap_or_default());
        }
    }

    pub fn next_tool(&mut self) {
        if let Some(current) = self.sidebar_state.selected() {
            let next = (current + 1).min(AnalysisTool::ALL.len() - 1);
            self.sidebar_state.select(Some(next));
        }
    }

    pub fn previous_tool(&mut self) {
        if let Some(current) = self.sidebar_state.selected()
            && current > 0
        {
            self.sidebar_state.select(Some(current - 1));
        }
    }

    pub fn open_distribution_detail(&mut self) {
        if self.focus == AnalysisFocus::Main
            && self.selected_tool == Some(AnalysisTool::DistributionAnalysis)
            && let Some(idx) = self.distribution_table_state.selected()
        {
            if let Some(results) = &self.distribution_results
                && let Some(dist_analysis) = results.distribution_analyses.get(idx)
            {
                self.selected_theoretical_distribution = dist_analysis.distribution_type;
            }
            self.view = AnalysisView::DistributionDetail;
            self.focus = AnalysisFocus::DistributionSelector;
            if self.selected_theoretical_distribution == DistributionType::Unknown {
                self.selected_theoretical_distribution = DistributionType::Normal;
            }
            self.distribution_selector_state.select(None);
        }
    }

    pub fn open_correlation_detail(&mut self) {
        if self.focus == AnalysisFocus::Main
            && self.selected_tool == Some(AnalysisTool::CorrelationMatrix)
            && let Some((row, col)) = self.selected_correlation
            && row != col
        {
            self.view = AnalysisView::CorrelationDetail;
        }
    }

    pub fn close_detail(&mut self) {
        self.view = AnalysisView::Main;
        self.focus = AnalysisFocus::Main;
    }

    pub fn scroll_left(&mut self) {
        if let Some(columns) = self.column_scroll_mut() {
            columns.left();
        }
    }

    pub fn scroll_right(&mut self) {
        if let Some(columns) = self.column_scroll_mut() {
            columns.right();
        }
    }

    /// The selected tool's statistic scroll, for the tools that scroll by statistic.
    pub fn column_scroll(&self) -> Option<&ColumnScroll> {
        match self.selected_tool {
            Some(AnalysisTool::Describe) => Some(&self.describe_columns),
            Some(AnalysisTool::DistributionAnalysis) => Some(&self.distribution_columns),
            _ => None,
        }
    }

    fn column_scroll_mut(&mut self) -> Option<&mut ColumnScroll> {
        match self.selected_tool {
            Some(AnalysisTool::Describe) => Some(&mut self.describe_columns),
            Some(AnalysisTool::DistributionAnalysis) => Some(&mut self.distribution_columns),
            _ => None,
        }
    }

    /// Read the view's sample whole while it has one (`sampled`), and the tools' own
    /// sample again once it has none.
    pub fn follow_view_sample(&mut self, sampled: bool) {
        match (sampled, self.own_sample.is_some()) {
            (true, false) => {
                let every = crate::analysis::sampling::Sample {
                    scope: crate::analysis::data_quality::QualityScope::CurrentView,
                    method: crate::analysis::sampling::SampleMethod::EveryRow,
                    ..self.sample.clone()
                };
                self.own_sample = Some(std::mem::replace(&mut self.sample, every));
            }
            (false, true) => {
                if let Some(own) = self.own_sample.take() {
                    self.sample = own;
                }
            }
            _ => {}
        }
    }

    pub fn quality_row_count(&self) -> usize {
        let Some(results) = self.quality.results.as_ref() else {
            return 0;
        };
        match self.quality.page {
            QualityPage::Setup => SetupRow::ALL.len(),
            QualityPage::TimeRoles => TemporalRole::ALL.len(),
            QualityPage::IntervalPairs => self.quality.plan.candidate_pairs().len(),
            // The scope's columns are not held here: `App` moves the list by them.
            QualityPage::Intent => 0,
            QualityPage::Intervals => results.temporal.len(),
            QualityPage::IntervalDetail => self.interval_facts().len(),
            QualityPage::Overview => self.quality.findings.shown(results.report()).len(),
            QualityPage::Columns | QualityPage::Detail => results.columns.len(),
            QualityPage::Segments => results.segments.len(),
            QualityPage::SegmentDetail => {
                crate::analysis::data_quality::segment_changes(results, self.quality.segment_index)
                    .len()
            }
            // The trend table's lines; the width only changes how many bars.
            QualityPage::Trends => {
                crate::analysis::quality_trends::trend_view(results, self.quality.metric, 1)
                    .lines
                    .len()
            }
            // At most one bar per segment: the width decides how many, and the page clamps
            // the cursor as it draws.
            QualityPage::TrendDetail => crate::analysis::quality_trends::trend_slots(results).len(),
            QualityPage::Gaps => {
                match crate::analysis::quality_trends::expected_gaps(
                    self.quality_result_plan(),
                    results,
                ) {
                    Some(crate::analysis::quality_trends::Gaps::Checked(check)) => check.runs.len(),
                    _ => 0,
                }
            }
            QualityPage::ExpectedWindows => EXPECTED_ROWS.len(),
        }
    }

    /// Whether the highlighted Overview entry is the clean-columns entry, which opens
    /// no rows and instead lists the checks.
    pub fn quality_selected_is_clean(&self) -> bool {
        self.quality.page == QualityPage::Overview
            && self
                .selected_finding()
                .is_some_and(|(_, finding)| finding.kind.is_none())
    }

    /// The report on screen and the finding under the cursor, as Overview lists
    /// them: narrowed and ordered.
    pub fn selected_finding(&self) -> Option<(&QualityReport, Finding)> {
        let report = self.quality.results.as_ref()?.report();
        let finding = self
            .quality
            .findings
            .selected(report, self.quality.table_state.selected()?)?
            .clone();
        Some((report, finding))
    }

    /// Narrow the findings to a column (`by_column`) or a check, from a list of
    /// those the report has, the current one selected.
    pub fn open_findings_picker(&mut self, by_column: bool) {
        let Some(results) = self.quality.results.as_ref() else {
            return;
        };
        let report = results.report();
        let view = &self.quality.findings;
        let findings = |count: usize| match count {
            0 => "none".to_string(),
            1 => "1 finding".to_string(),
            count => format!("{} findings", crate::numfmt::group_chrome(count)),
        };
        let (title, choices, current) = if by_column {
            let columns = crate::analysis::quality_report::column_choices(report, results);
            let width = columns
                .iter()
                .map(|(name, _)| crate::glyphs::display_width(name))
                .max()
                .unwrap_or(0);
            let current = view
                .column
                .as_ref()
                .and_then(|column| columns.iter().position(|(name, _)| name == column))
                .map_or(0, |position| position + 1);
            let mut choices = vec![("All columns".to_string(), PlanChoice::FindingColumn(None))];
            choices.extend(columns.into_iter().map(|(name, count)| {
                let pad = width.saturating_sub(crate::glyphs::display_width(&name));
                (
                    format!("{name}{}  {}", " ".repeat(pad), findings(count)),
                    PlanChoice::FindingColumn(Some(name)),
                )
            }));
            ("Findings by Column", choices, current)
        } else {
            let checks = crate::analysis::quality_report::check_choices(report);
            let width = checks
                .iter()
                .map(|(name, _)| crate::glyphs::display_width(name))
                .max()
                .unwrap_or(0);
            let current = view
                .check
                .and_then(|check| checks.iter().position(|(name, _)| *name == check))
                .map_or(0, |position| position + 1);
            let mut choices = vec![("All types".to_string(), PlanChoice::FindingCheck(None))];
            choices.extend(checks.into_iter().map(|(name, count)| {
                let pad = width.saturating_sub(crate::glyphs::display_width(name));
                (
                    format!("{name}{}  {}", " ".repeat(pad), findings(count)),
                    PlanChoice::FindingCheck(Some(name)),
                )
            }));
            ("Findings by Type", choices, current)
        };
        let (labels, choices): (Vec<_>, Vec<_>) = choices.into_iter().unzip();
        let mut state = crate::widgets::ui::PickerState::new(labels);
        state.select_original(current);
        self.quality.picker = Some(PlanPicker {
            title: title.to_string(),
            choices,
            state,
        });
    }

    /// The next order for the findings, keeping the finding under the cursor under it.
    pub fn cycle_findings_order(&mut self) {
        let selected = self.selected_finding().map(|(_, finding)| finding);
        self.quality.findings.order = self.quality.findings.order.next();
        self.reselect_finding(selected);
    }

    /// Show every finding again, in the order chosen.
    pub fn clear_findings_narrowing(&mut self) {
        let selected = self.selected_finding().map(|(_, finding)| finding);
        self.quality.findings.column = None;
        self.quality.findings.check = None;
        self.reselect_finding(selected);
    }

    /// Put the cursor on `finding` where the list now shows it, or on the first.
    fn reselect_finding(&mut self, finding: Option<Finding>) {
        let position = self.quality.results.as_ref().and_then(|results| {
            let report = results.report();
            let finding = finding?;
            let shown = self.quality.findings.shown(report);
            shown.iter().position(|index| {
                let listed = &report.findings[*index];
                listed.same_as(&finding)
            })
        });
        self.quality.table_state.select(Some(position.unwrap_or(0)));
        *self.quality.table_state.offset_mut() = 0;
    }

    /// Whether `s` opens the Sample form: on a tool's main view with nothing else
    /// holding keys (run, popup, editor, text field).
    pub fn sample_key_opens_form(&self) -> bool {
        self.view == AnalysisView::Main
            && self.selected_tool.is_some()
            && self.computing.is_none()
            && self.quality.picker.is_none()
            && !matches!(
                self.quality.page,
                QualityPage::TimeRoles
                    | QualityPage::IntervalPairs
                    | QualityPage::ExpectedWindows
                    | QualityPage::Intent
            )
            && !self.quality.show_access
            && !self.quality.observation_detail
            && self.quality.evidence_read.is_none()
            && self.quality.export.is_none()
            && self.quality.intent_form.is_none()
            && self.sample_form.is_none()
    }

    /// Whether the export dialog's path owns typed characters.
    pub fn export_typing(&self) -> bool {
        self.quality
            .export
            .as_ref()
            .is_some_and(|form| !form.on_format)
    }

    /// Whether a Column intent field owns typed characters, so Ctrl-C and `?` type.
    pub fn intent_typing(&self) -> bool {
        self.quality
            .intent_form
            .as_ref()
            .is_some_and(crate::analysis::intent_modal::IntentForm::typing)
    }

    /// Whether the Sample form's scope field owns typed characters, so Ctrl-C and `?`
    /// type.
    pub fn sample_scope_typing(&self) -> bool {
        self.sample_form.as_ref().is_some_and(|form| {
            form.field.is_text() && (!form.inline || self.focus == AnalysisFocus::Main)
        })
    }

    /// Whether the Expected editor's From or Before has the cursor, so all but its own
    /// keys type.
    pub fn quality_expected_typing(&self) -> bool {
        self.quality.page == QualityPage::ExpectedWindows
            && self
                .quality
                .expected_form
                .as_ref()
                .is_some_and(ExpectedForm::typing)
    }

    /// Open the bars of the Trends line under the cursor, the first bar selected.
    pub fn open_trend_detail(&mut self) {
        let line = self.quality.table_state.selected().unwrap_or(0);
        self.quality.trend_line = line;
        self.set_quality_page(QualityPage::TrendDetail);
    }

    /// The next measure in a bar's detail, on the same column's line. A column with
    /// nothing to draw in it has no line, and Trends lists what does.
    pub fn cycle_trend_detail_metric(&mut self) {
        let Some(results) = self.quality.results.as_ref() else {
            return;
        };
        let view = crate::analysis::quality_trends::trend_view(results, self.quality.metric, 1);
        let line = view
            .lines
            .get(self.quality.trend_line)
            .map(|line| (line.measure, line.names.clone()));
        self.cycle_quality_metric();
        let Some(results) = self.quality.results.as_ref() else {
            return;
        };
        let view = crate::analysis::quality_trends::trend_view(results, self.quality.metric, 1);
        let found = line.and_then(|(measure, names)| {
            view.lines.iter().position(|candidate| {
                candidate.measure == measure
                    || candidate
                        .names
                        .iter()
                        .any(|name| !candidate.rows() && names.contains(name))
            })
        });
        match found {
            Some(index) => self.quality.trend_line = index,
            None => {
                self.quality.trend_line = 0;
                self.close_to_trends();
            }
        }
    }

    /// Back to Trends from a bar detail or the gaps, the line still selected.
    pub fn close_to_trends(&mut self) {
        let line =
            (self.quality.page == QualityPage::TrendDetail).then_some(self.quality.trend_line);
        self.set_quality_page(QualityPage::Trends);
        self.quality.table_state.select(Some(line.unwrap_or(0)));
    }

    pub fn set_quality_page(&mut self, page: QualityPage) {
        self.quality.page = page;
        self.quality.observation_detail = false;
        self.quality.evidence_read = None;
        self.quality.table_state.select(Some(0));
    }

    /// Move between the column lens and its detail, keeping the selected column.
    pub fn set_quality_column_page(&mut self, page: QualityPage) {
        // Detail moves the same selection with Up/Down, so take it from there too.
        if matches!(
            self.quality.page,
            QualityPage::Columns | QualityPage::Detail
        ) {
            self.quality.column_index = self.quality.table_state.selected().unwrap_or(0);
        }
        self.set_quality_page(page);
        self.quality
            .table_state
            .select(Some(self.quality.column_index));
    }

    /// Open the highlighted segment's columns, or go back to the list with the
    /// segment still selected.
    pub fn open_segment_detail(&mut self) {
        if let Some(segment) = self.selected_segment() {
            self.quality.segment_index = segment;
            self.set_quality_page(QualityPage::SegmentDetail);
        }
    }

    pub fn close_segment_detail(&mut self) {
        self.set_quality_page(QualityPage::Segments);
        let position = self
            .segment_order()
            .iter()
            .position(|segment| *segment == self.quality.segment_index);
        self.quality.table_state.select(Some(position.unwrap_or(0)));
    }

    /// The order Segments lists its rows in.
    pub fn segment_order(&self) -> Vec<usize> {
        self.quality
            .results
            .as_ref()
            .map(|results| {
                crate::analysis::data_quality::segment_order(
                    results,
                    self.quality.segments_by_change,
                )
            })
            .unwrap_or_default()
    }

    /// The segment under the cursor on Segments, whichever order it is listed in.
    pub fn selected_segment(&self) -> Option<usize> {
        let position = self.quality.table_state.selected()?;
        self.segment_order().get(position).copied()
    }

    /// List segments in their own order or clearest change first, keeping the one
    /// under the cursor under it.
    pub fn toggle_segment_order(&mut self) {
        let segment = self.selected_segment();
        self.quality.segments_by_change = !self.quality.segments_by_change;
        let position = segment
            .and_then(|segment| self.segment_order().iter().position(|s| *s == segment))
            .unwrap_or(0);
        self.quality.table_state.select(Some(position));
    }

    /// Open the highlighted interval's detail, its first count under the cursor.
    pub fn open_interval_detail(&mut self) {
        let Some(index) = self.quality.table_state.selected() else {
            return;
        };
        if self
            .quality
            .results
            .as_ref()
            .is_some_and(|results| index < results.temporal.len())
        {
            self.quality.interval_index = index;
            self.set_quality_page(QualityPage::IntervalDetail);
        }
    }

    /// Back to the list, the interval still selected.
    pub fn close_interval_detail(&mut self) {
        self.set_quality_page(QualityPage::Intervals);
        self.quality
            .table_state
            .select(Some(self.quality.interval_index));
    }

    /// The counts an interval's detail lists, each with rows it can open: those
    /// the interval measured, in the order the detail shows them.
    pub fn interval_facts(&self) -> Vec<IntervalFact> {
        let plan = self.quality_result_plan();
        self.quality
            .results
            .as_ref()
            .and_then(|results| results.temporal.get(self.quality.interval_index))
            .map(|profile| {
                IntervalFact::ALL
                    .into_iter()
                    .filter(|fact| profile.count(*fact, plan).is_some())
                    .collect()
            })
            .unwrap_or_default()
    }

    /// The count under the cursor in an interval's detail.
    pub fn selected_interval_fact(&self) -> Option<IntervalFact> {
        let facts = self.interval_facts();
        facts
            .get(self.quality.table_state.selected().unwrap_or(0))
            .copied()
    }

    /// The rows behind the selected count in an interval's detail, when its values
    /// identify them: a predicate over the run's rows, with a label. `schema` (where
    /// known) lets a partition segment compare in its column's type.
    pub fn interval_evidence(
        &self,
        schema: Option<&polars::prelude::Schema>,
    ) -> Option<(polars::prelude::Expr, String, usize)> {
        let results = self.quality.results.as_ref()?;
        if !matches!(
            results.precision,
            crate::analysis::data_quality::QualityPrecision::Exact
                | crate::analysis::data_quality::QualityPrecision::Sampled
        ) {
            return None;
        }
        let plan = self.quality_result_plan();
        let profile = results.temporal.get(self.quality.interval_index)?;
        let fact = self.selected_interval_fact()?;
        let (count, _) = profile.count(fact, plan)?;
        if count == 0 {
            return None;
        }
        let predicate = profile.evidence_predicate(fact, plan, schema)?;
        Some((
            predicate,
            format!(
                "Data Quality / {} / {} / {}",
                profile.label(),
                profile.segment,
                fact.short()
            ),
            count,
        ))
    }

    /// Move the finding popup by `rows`, within what it last drew.
    pub fn scroll_quality_detail(&mut self, rows: i32) {
        let scroll = &mut self.quality.detail_scroll;
        scroll.offset = (scroll.offset as i32 + rows).clamp(0, scroll.max as i32) as u16;
    }

    /// Show a tab, keeping the column in view across Columns, Segments and Trends.
    pub fn show_quality_tab(&mut self, page: QualityPage) {
        if matches!(
            self.quality.page,
            QualityPage::Columns | QualityPage::Detail
        ) {
            self.quality.column_index = self.quality.table_state.selected().unwrap_or(0);
        }
        self.set_quality_page(page);
        if page == QualityPage::Columns {
            self.quality
                .table_state
                .select(Some(self.quality.column_index));
        }
    }

    /// The next or previous tab, stopping at either end.
    pub fn step_quality_tab(&mut self, forward: bool) {
        let tabs = QualityPage::TABS;
        let Some(at) = tabs
            .iter()
            .position(|page| *page == self.quality.page.tab())
        else {
            return;
        };
        let next = if forward {
            (at + 1).min(tabs.len() - 1)
        } else {
            at.saturating_sub(1)
        };
        if next != at {
            self.show_quality_tab(tabs[next]);
        }
    }

    pub fn cycle_quality_metric(&mut self) {
        let current = QualityMetric::ALL
            .iter()
            .position(|metric| *metric == self.quality.metric)
            .unwrap_or(0);
        self.quality.metric = QualityMetric::ALL[(current + 1) % QualityMetric::ALL.len()];
    }

    /// The plan the on-screen result was measured with (the plan until a run exists),
    /// so a draft never relabels what was measured.
    pub fn quality_result_plan(&self) -> &DataQualityPlan {
        self.quality
            .last_plan
            .as_ref()
            .unwrap_or(&self.quality.plan)
    }

    /// The plan differs from the one the result on screen was measured with.
    pub fn quality_plan_pending(&self) -> bool {
        self.quality.results.is_some()
            && self.quality.last_plan.as_ref() != Some(&self.quality.plan)
    }

    /// The Setup row under the cursor.
    pub fn setup_row(&self) -> SetupRow {
        SetupRow::at(self.quality.plan_field)
    }

    /// Whether Setup holds staged changes Esc would discard.
    pub fn setup_edited(&self) -> bool {
        self.quality
            .setup_before
            .as_ref()
            .is_some_and(|before| *before != self.quality.plan)
    }

    /// The choices a Setup row offers, in the words the header uses.
    pub fn plan_choices(&self, row: SetupRow, context: &PlanContext) -> Vec<(String, PlanChoice)> {
        match row {
            SetupRow::Grain => {
                let mut grains = vec![QualityGrain::Dataset];
                if context.files {
                    grains.push(QualityGrain::File);
                }
                grains.extend(
                    context
                        .partitions
                        .iter()
                        .cloned()
                        .map(QualityGrain::Partition),
                );
                // Any date column can split by day, week or month; hours only where there are times.
                for (column, has_time) in &context.time_columns {
                    for every in QUALITY_WINDOW_WIDTHS {
                        if every == "1h" && !has_time {
                            continue;
                        }
                        grains.push(QualityGrain::TimeWindows {
                            column: column.clone(),
                            every: every.to_string(),
                        });
                    }
                }
                grains.extend([100_000, 1_000_000].map(QualityGrain::RowChunks));
                if !grains.contains(&self.quality.plan.grain) {
                    grains.insert(0, self.quality.plan.grain.clone());
                }
                grains
                    .into_iter()
                    .map(|grain| (grain.label(), PlanChoice::Grain(grain)))
                    .collect()
            }
            SetupRow::Values => {
                // The draft's sample says which kind of read it is.
                let read = if self.quality.plan.method
                    == crate::analysis::sampling::SampleMethod::EveryRow
                {
                    QualityCompute::Full
                } else {
                    QualityCompute::Sample
                };
                vec![
                    ("read".to_string(), PlanChoice::Values(read)),
                    (
                        "file metadata only".to_string(),
                        PlanChoice::Values(QualityCompute::Metadata),
                    ),
                ]
            }
            SetupRow::Compare => [
                QualityComparison::None,
                QualityComparison::Previous,
                QualityComparison::Baseline,
            ]
            .into_iter()
            .map(|comparison| {
                (
                    comparison.choice_label().to_string(),
                    PlanChoice::Compare(comparison),
                )
            })
            .collect(),
            SetupRow::WindowBy if !self.quality.plan.windows_intervals() => Vec::new(),
            SetupRow::WindowBy => IntervalClock::ALL
                .into_iter()
                .map(|clock| (clock.label().to_string(), PlanChoice::Clock(clock)))
                .collect(),
            SetupRow::Latency if self.quality.plan.interval_pairs().is_empty() => Vec::new(),
            SetupRow::Latency => [None, Some(3_600), Some(86_400), Some(604_800)]
                .into_iter()
                .map(|seconds| (threshold_label(seconds), PlanChoice::Latency(seconds)))
                .collect(),
            // Each text column with its first value on screen, so the choice is among things
            // seen.
            SetupRow::TextAsTime => context
                .text_columns
                .iter()
                .map(|(column, examples)| {
                    let label = match (self.quality.plan.time_format(column), examples.first()) {
                        (Some(format), _) => format!("{column}  as {}", format.label()),
                        (None, Some(example)) => format!("{column}  {example}"),
                        (None, None) => column.clone(),
                    };
                    (label, PlanChoice::TextColumn(column.clone()))
                })
                .collect(),
            SetupRow::Sample
            | SetupRow::TimeRoles
            | SetupRow::Intervals
            | SetupRow::Expected
            | SetupRow::Intent => Vec::new(),
        }
    }

    /// Open the focused Setup row's choices, the current one selected.
    pub fn open_plan_picker(&mut self, row: SetupRow, context: &PlanContext) {
        let choices = self.plan_choices(row, context);
        self.quality.plan_field = row.index();
        self.show_picker(row.label().to_string(), choices);
    }

    fn show_picker(&mut self, title: String, choices: Vec<(String, PlanChoice)>) {
        if choices.is_empty() {
            return;
        }
        let current = choices
            .iter()
            .position(|(_, choice)| choice.is_current(&self.quality.plan))
            .unwrap_or(0);
        let (labels, choices): (Vec<_>, Vec<_>) = choices.into_iter().unzip();
        let mut state = crate::widgets::ui::PickerState::new(labels);
        state.select_original(current);
        self.quality.picker = Some(PlanPicker {
            title,
            choices,
            state,
        });
    }

    /// How `column` can be read as time: each format with how many of the on-screen
    /// `examples` it reads, best first, and reading as text again when it has a format.
    pub fn open_format_picker(&mut self, column: &str, examples: &[String]) {
        let mut formats = TIME_FORMATS
            .iter()
            .enumerate()
            .map(|(order, (kind, format))| {
                let interpretation = TimeInterpretation {
                    column: column.to_string(),
                    kind: *kind,
                    format: format.to_string(),
                };
                let read = examples
                    .iter()
                    .filter(|value| interpretation.reads(value))
                    .count();
                (read, order, *kind, *format)
            })
            .collect::<Vec<_>>();
        // Most read first; the offered order among equals, so the list is stable.
        formats.sort_by_key(|(read, order, _, _)| (std::cmp::Reverse(*read), *order));
        let mut choices = formats
            .into_iter()
            .map(|(read, _, kind, format)| {
                // The count first, so a narrow list clips the format, not the evidence.
                let label = if examples.is_empty() {
                    format!("{} {format}", kind.label())
                } else {
                    format!(
                        "reads {read} of {}  {} {format}",
                        examples.len(),
                        kind.label()
                    )
                };
                (
                    label,
                    PlanChoice::Format(column.to_string(), Some((kind, format))),
                )
            })
            .collect::<Vec<_>>();
        if self.quality.plan.time_format(column).is_some() {
            choices.push((
                "text, not a time".to_string(),
                PlanChoice::Format(column.to_string(), None),
            ));
        }
        self.show_picker(format!("Read {column} As"), choices);
    }

    /// Take the picker's selection into the plan and close it. Returns a text column
    /// chosen to read as time: its format is the next choice.
    pub fn choose_plan_picker(&mut self) -> Option<String> {
        let picker = self.quality.picker.take()?;
        let choice = picker
            .state
            .selected_original()
            .and_then(|index| picker.choices.get(index))?;
        let plan = &mut self.quality.plan;
        match choice.clone() {
            PlanChoice::Grain(grain) => {
                if plan.grain != grain {
                    plan.baseline_segment = None;
                }
                plan.grain = grain;
            }
            PlanChoice::Values(compute) => plan.compute = compute,
            PlanChoice::Compare(comparison) => {
                plan.comparison = comparison;
                if comparison != QualityComparison::Baseline {
                    plan.baseline_segment = None;
                }
            }
            PlanChoice::Latency(seconds) => plan.latency_threshold_seconds = seconds,
            PlanChoice::Clock(clock) => plan.interval_clock = clock,
            PlanChoice::TextColumn(column) => return Some(column),
            PlanChoice::Format(column, format) => set_time_format(plan, &column, format),
            PlanChoice::FindingColumn(column) => {
                let selected = self.selected_finding().map(|(_, finding)| finding);
                self.quality.findings.column = column;
                self.reselect_finding(selected);
            }
            PlanChoice::FindingCheck(check) => {
                let selected = self.selected_finding().map(|(_, finding)| finding);
                self.quality.findings.check = check;
                self.reselect_finding(selected);
            }
        }
        None
    }

    /// The next or previous choice of a Setup row whose choices are a short list,
    /// in place: ←→ on Grain, Compare, Values, Latency and Window by.
    pub fn cycle_setup_choice(&mut self, row: SetupRow, context: &PlanContext, forward: bool) {
        let choices = self.plan_choices(row, context);
        if choices.is_empty() || matches!(row, SetupRow::TextAsTime) {
            return;
        }
        let current = choices
            .iter()
            .position(|(_, choice)| choice.is_current(&self.quality.plan))
            .unwrap_or(0);
        let next = if forward {
            (current + 1).min(choices.len() - 1)
        } else {
            current.saturating_sub(1)
        };
        let (labels, choices): (Vec<_>, Vec<_>) = choices.into_iter().unzip();
        let mut state = crate::widgets::ui::PickerState::new(labels);
        state.select_original(next);
        self.quality.picker = Some(PlanPicker {
            title: row.label().to_string(),
            choices,
            state,
        });
        self.choose_plan_picker();
    }

    pub fn cycle_quality_time_role(
        &mut self,
        role_index: usize,
        columns: &[String],
        forward: bool,
    ) {
        let Some(role) = TemporalRole::ALL.get(role_index).copied() else {
            return;
        };
        let current = self
            .quality
            .plan
            .temporal_roles
            .iter()
            .find(|assignment| assignment.role == role)
            .and_then(|assignment| columns.iter().position(|name| name == &assignment.column))
            .map(|index| index + 1)
            .unwrap_or(0);
        let choices = columns.len() + 1;
        let next = if forward {
            (current + 1) % choices
        } else if current == 0 {
            choices - 1
        } else {
            current - 1
        };
        self.quality
            .plan
            .temporal_roles
            .retain(|assignment| assignment.role != role);
        if next > 0 {
            self.quality
                .plan
                .temporal_roles
                .push(TemporalRoleAssignment {
                    role,
                    column: columns[next - 1].clone(),
                    timezone: None,
                });
        }
    }

    /// Move the focused tool's cursor by `step` in `rows` rows, ten to a page. The
    /// correlation matrix moves its row, keeping its column; Home and End take the first
    /// and last off-diagonal pair.
    pub fn move_row(&mut self, step: crate::app::form::ListMove, rows: usize) {
        use crate::app::form::ListMove;
        const PAGE: usize = 10;
        let to = |at: Option<usize>| match (at, step) {
            (Some(at), _) => Some(step.apply(at, rows, PAGE)),
            // Nothing selected yet: Down and Home start the cursor at the top, End at
            // the bottom.
            (None, ListMove::Down | ListMove::Home) => Some(0),
            (None, ListMove::End) => rows.checked_sub(1),
            (None, _) => None,
        };
        match self.selected_tool {
            Some(AnalysisTool::Describe) => {
                if let Some(next) = to(self.table_state.selected()) {
                    self.table_state.select(Some(next));
                }
            }
            Some(AnalysisTool::DistributionAnalysis) => {
                if let Some(next) = to(self.distribution_table_state.selected()) {
                    self.distribution_table_state.select(Some(next));
                    self.selected_distribution = Some(next);
                }
            }
            Some(AnalysisTool::CorrelationMatrix) => {
                let n = self.correlation_size();
                let cell = match (step, self.selected_correlation) {
                    (ListMove::Down, _) => return self.move_correlation_cell((1, 0)),
                    (ListMove::Home, _) if n > 0 => (0, 1.min(n - 1)),
                    (ListMove::End, _) if n > 0 => (n - 1, (n - 1).saturating_sub(1)),
                    (ListMove::Up | ListMove::PageUp | ListMove::PageDown, Some((row, col))) => {
                        (step.apply(row, rows, PAGE), col)
                    }
                    _ => return,
                };
                self.selected_correlation = Some(cell);
                self.correlation_table_state.select(Some(cell.0));
            }
            Some(AnalysisTool::DataQuality) => {
                let at = self.quality.table_state.selected().unwrap_or(0);
                self.quality
                    .table_state
                    .select(Some(step.apply(at, rows, PAGE)));
            }
            None => {}
        }
    }

    /// Install the matrix a run read. The cursor stays if still a cell, else starts on
    /// the first off-diagonal pair, where Enter opens a detail.
    pub fn install_correlations(&mut self, results: AnalysisResults) {
        let n = results
            .correlation_matrix
            .as_ref()
            .map_or(0, |matrix| matrix.columns.len());
        self.correlation_results = Some(results);
        let cell = match self.selected_correlation {
            Some((row, col)) if row < n && col < n => (row, col),
            _ if n >= 2 => (0, 1),
            _ => (0, 0),
        };
        self.selected_correlation = Some(cell);
        self.correlation_table_state.select(Some(cell.0));
    }

    /// The number of columns in the correlation matrix on screen.
    pub fn correlation_size(&self) -> usize {
        self.correlation_results
            .as_ref()
            .and_then(|results| results.correlation_matrix.as_ref())
            .map_or(0, |matrix| matrix.columns.len())
    }

    /// The families the distribution detail's selector lists for the column under
    /// the cursor.
    pub fn distribution_choices(&self) -> usize {
        let row = self.distribution_table_state.selected().unwrap_or(0);
        self.distribution_results
            .as_ref()
            .and_then(|results| results.distribution_analyses.get(row))
            .map_or(0, |analysis| {
                crate::analysis::distribution_fit::listing_order(&analysis.fits).len()
            })
    }

    /// Move the correlation cursor by `(rows, columns)`, stopping at edges; the matrix
    /// scrolls to keep it in view as it draws.
    pub fn move_correlation_cell(&mut self, (rows, cols): (isize, isize)) {
        let n = self.correlation_size();
        if n == 0 {
            return;
        }
        if let Some((row, col)) = self.selected_correlation {
            let row = row.saturating_add_signed(rows).min(n - 1);
            let col = col.saturating_add_signed(cols).min(n - 1);
            self.selected_correlation = Some((row, col));
            self.correlation_table_state.select(Some(row));
        }
    }

    pub fn next_distribution(&mut self) {
        let max_idx = self.distribution_choices().saturating_sub(1);

        if let Some(current) = self.distribution_selector_state.selected() {
            let next = (current + 1).min(max_idx);
            self.distribution_selector_state.select(Some(next));
            self.select_distribution();
        } else {
            self.distribution_selector_state.select(Some(0));
            self.select_distribution();
        }
    }

    pub fn previous_distribution(&mut self) {
        if let Some(current) = self.distribution_selector_state.selected() {
            if current > 0 {
                self.distribution_selector_state.select(Some(current - 1));
                self.select_distribution();
            }
        } else {
            self.distribution_selector_state.select(Some(0));
            self.select_distribution();
        }
    }

    pub fn select_distribution(&mut self) {
        if let Some(idx) = self.distribution_selector_state.selected()
            && let Some(results) = &self.distribution_results
        {
            let dist_analysis_idx = self.distribution_table_state.selected().unwrap_or(0);
            if let Some(dist_analysis) = results.distribution_analyses.get(dist_analysis_idx) {
                // The order the selector lists them in.
                let distribution_scores =
                    crate::analysis::distribution_fit::listing_order(&dist_analysis.fits);
                let valid_idx = idx.min(distribution_scores.len().saturating_sub(1));
                if let Some(dist_type) = distribution_scores.get(valid_idx) {
                    self.selected_theoretical_distribution = *dist_type;
                    if idx != valid_idx {
                        self.distribution_selector_state.select(Some(valid_idx));
                    }
                }
            }
        }
    }
}

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

    /// Weekdays stated for days, then a coarser grain: the editor offers what the
    /// grain allows and shows what Setup and the check read, every week.
    #[test]
    fn expected_weekdays_read_as_every_window_on_weeks() {
        let theme =
            crate::config::Theme::from_config(&crate::config::ThemeConfig::default()).unwrap();
        let mut plan = DataQualityPlan {
            grain: QualityGrain::TimeWindows {
                column: "day".to_string(),
                every: "1d".to_string(),
            },
            expected: Some(crate::analysis::data_quality::ExpectedWindows {
                weekdays: true,
                ..Default::default()
            }),
            ..DataQualityPlan::default()
        };
        assert_eq!(
            ExpectedForm::new(&plan, &theme).cadence,
            ExpectedCadence::Weekdays
        );
        plan.grain = QualityGrain::TimeWindows {
            column: "day".to_string(),
            every: "1w".to_string(),
        };
        let form = ExpectedForm::new(&plan, &theme);
        assert_eq!(form.cadence, ExpectedCadence::Every);
        assert_eq!(form.cadence_label("1w"), "every week");
        assert!(!form.expected().unwrap().unwrap().weekdays);
    }

    /// Grain choices come from the data: files, partition columns, and a day, week
    /// or month of any date column (hours only where there are times), then chunks.
    #[test]
    fn grain_choices_come_from_the_data() {
        let mut modal = AnalysisModal::default();
        let context = PlanContext {
            partitions: vec!["year".to_string()],
            time_columns: vec![("date".to_string(), false), ("stamp".to_string(), true)],
            files: true,
            text_columns: Vec::new(),
        };
        let labels = modal
            .plan_choices(SetupRow::Grain, &context)
            .into_iter()
            .map(|(label, _)| label)
            .collect::<Vec<_>>();
        assert_eq!(
            labels,
            [
                "whole dataset",
                "by file",
                "by year",
                "by day of date",
                "by week of date",
                "by month of date",
                "by hour of stamp",
                "by day of stamp",
                "by week of stamp",
                "by month of stamp",
                "in chunks of 100,000 rows",
                "in chunks of 1,000,000 rows",
            ]
        );
        // Choosing opens the list on the current value and sets the one chosen.
        modal.open_plan_picker(SetupRow::Grain, &context);
        let picker = modal.quality.picker.as_mut().unwrap();
        assert_eq!(picker.state.selected_original(), Some(0));
        picker.state.move_down();
        picker.state.move_down();
        picker.state.move_down();
        modal.choose_plan_picker();
        assert!(modal.quality.picker.is_none());
        assert_eq!(
            modal.quality.plan.grain,
            QualityGrain::TimeWindows {
                column: "date".to_string(),
                every: "1d".to_string()
            }
        );
    }

    /// Values: read or metadata only; which of sample and full scan a read is, the
    /// shared sample says.
    #[test]
    fn a_read_is_the_samples_kind() {
        let mut modal = AnalysisModal::default();
        let context = PlanContext::default();
        modal.quality.plan.compute = QualityCompute::Metadata;
        modal.open_plan_picker(SetupRow::Values, &context);
        modal
            .quality
            .picker
            .as_mut()
            .unwrap()
            .state
            .select_original(0);
        modal.choose_plan_picker();
        assert_eq!(modal.quality.plan.compute, QualityCompute::Sample);
        modal.quality.plan.method = crate::analysis::sampling::SampleMethod::EveryRow;
        modal.open_plan_picker(SetupRow::Values, &context);
        modal.choose_plan_picker();
        assert_eq!(modal.quality.plan.compute, QualityCompute::Full);
        modal.open_plan_picker(SetupRow::Latency, &context);
        assert!(
            modal.quality.picker.is_none(),
            "no threshold without an interval to measure"
        );
    }

    /// A text column is read as time in two choices, the column and then its
    /// format, the formats that read the values on screen first; reading it as text
    /// again takes back a time window that needed it.
    #[test]
    fn text_is_read_as_time_through_a_chosen_format() {
        let mut modal = AnalysisModal::default();
        let context = PlanContext {
            text_columns: vec![(
                "created".to_string(),
                vec!["2024-01-31 08:15:00".to_string()],
            )],
            ..PlanContext::default()
        };
        modal.open_plan_picker(SetupRow::TextAsTime, &context);
        assert_eq!(modal.choose_plan_picker(), Some("created".to_string()));
        modal.open_format_picker("created", &["2024-01-31 08:15:00".to_string()]);
        let picker = modal.quality.picker.as_ref().unwrap();
        assert_eq!(picker.title, "Read created As");
        let first = picker.state.filtered()[0].1.to_string();
        assert_eq!(first, "reads 1 of 1  datetime %Y-%m-%d %H:%M:%S");
        assert_eq!(modal.choose_plan_picker(), None);
        let format = modal.quality.plan.time_format("created").unwrap();
        assert_eq!(format.kind, TimeKind::Datetime);

        // Now a time window can split by it; as text again, the window goes.
        let windows = PlanContext {
            time_columns: vec![("created".to_string(), true)],
            ..context.clone()
        };
        modal.open_plan_picker(SetupRow::Grain, &windows);
        let picker = modal.quality.picker.as_mut().unwrap();
        picker.state.move_down();
        picker.state.move_down();
        modal.choose_plan_picker();
        assert!(matches!(
            modal.quality.plan.grain,
            QualityGrain::TimeWindows { .. }
        ));
        modal.open_format_picker("created", &[]);
        let picker = modal.quality.picker.as_mut().unwrap();
        let text = picker
            .state
            .filtered()
            .iter()
            .position(|(_, label)| *label == "text, not a time")
            .unwrap();
        for _ in 0..text {
            picker.state.move_down();
        }
        modal.choose_plan_picker();
        assert!(modal.quality.plan.time_formats.is_empty());
        assert_eq!(modal.quality.plan.grain, QualityGrain::Dataset);
    }
}