//! The two front ends draw the same grid frame (improvise-anr9/s1xw). The
//! shipped divergence and the injected faults: `context/test-evidence/tui.md`.

use improvise::model::cell::{CellKey, CellValue};
use improvise::ui::app::{App, AppMode, ViewCursor};
use improvise::ui::grid::GridWidget;
use improvise::view::{Axis, GridLayout, GroupFold};
use improvise::workbook::Workbook;
use improvise_command::ui::project;
use improvise_protocol::{FrameEntry, GridCache, Snapshot, ViewState};
use improvise_wasm_client::render::{RenderModel, RenderRow};
use ratatui::{buffer::Buffer, layout::Rect, widgets::Widget};

fn coord(pairs: &[(&str, &str)]) -> CellKey {
    CellKey::new(
        pairs
            .iter()
            .map(|(c, i)| (c.to_string(), i.to_string()))
            .collect(),
    )
}

/// Both axes multi-level and grouped. Its two deliberate asymmetries — Carol
/// outside Family, Sep ungrouped — are in `context/test-evidence/tui.md`.
fn two_level_rows() -> Workbook {
    let mut m = Workbook::new("Test");
    m.add_category("Type").unwrap();
    m.add_category("Month").unwrap();
    m.add_category("Recipient").unwrap();
    m.add_item("Type", "Food").unwrap();
    m.add_item("Type", "Clothing").unwrap();
    m.add_item_in_group("Month", "Jan", "Q1").unwrap();
    m.add_item_in_group("Month", "Feb", "Q1").unwrap();
    m.active_view_mut().set_expand_depth("Month", 1);
    m.add_item("Month", "Sep").unwrap();
    m.add_item("Recipient", "Carol").unwrap();
    m.add_item_in_group("Recipient", "Alice", "Family").unwrap();
    m.add_item_in_group("Recipient", "Bob", "Family").unwrap();
    m.active_view_mut().set_expand_depth("Recipient", 1);
    m.active_view_mut().set_axis("Recipient", Axis::Row);
    m.add_item("_Measure", "Revenue").unwrap();
    m.add_item("_Measure", "Cost").unwrap();
    m.active_view_mut().set_axis("_Measure", Axis::Column);
    for t in ["Food", "Clothing"] {
        for r in ["Carol", "Alice", "Bob"] {
            for mo in ["Jan", "Feb", "Sep"] {
                for meas in ["Revenue", "Cost"] {
                    m.model.set_cell(
                        coord(&[
                            ("Type", t),
                            ("Month", mo),
                            ("Recipient", r),
                            ("_Measure", meas),
                        ]),
                        CellValue::Number(1.0),
                    );
                }
            }
        }
    }
    m
}

/// The one cache both ends are driven from — built exactly as the TUI builds
/// it, over the whole grid at offsets zero (gotcha 44).
fn whole_grid(wb: &mut Workbook) -> (App, GridCache) {
    let none_cats = wb.active_view().none_cats();
    wb.model.recompute_formulas(&none_cats);
    let app = App::new(wb.clone(), None);
    let cache = project::grid_of(
        &app,
        project::Viewport {
            row_offset: 0,
            col_offset: 0,
            rows: app.layout.row_count(),
            cols: app.layout.col_count(),
        },
    );
    (app, cache)
}

/// The row-header text the TUI *paints*, sliced by `AxisFrame::header_widths`
/// — the widget's own rule, never a second reading (improvise-1125).
fn tui_row_headers(wb: &Workbook, cache: &GridCache) -> Vec<Vec<String>> {
    let lines = tui_lines(wb, cache);
    let sep = header_rule(&lines);
    let widths = cache.row_frame.header_widths();
    lines[sep + 1..]
        .iter()
        // The body ends at the blank space below the grid, or at the rule
        // above the totals strip — which is not a row of the frame.
        .take_while(|l| !l.trim().is_empty() && !l.trim_end().chars().all(|c| c == '─'))
        .map(|line| {
            let chars: Vec<char> = line.chars().collect();
            let mut at = 0usize;
            widths
                .iter()
                .map(|w| {
                    let end = (at + *w as usize).min(chars.len());
                    let cell: String = chars[at.min(chars.len())..end].iter().collect();
                    at = end;
                    cell.trim_end().to_string()
                })
                .collect()
        })
        .collect()
}

/// One painted header line, cut by the cache's own `col_widths` for the same
/// reason. Labels are right-aligned into `width - 1`, so a trim recovers them.
fn tui_header_cells(line: &str, cache: &GridCache) -> Vec<String> {
    let chars: Vec<char> = line.chars().collect();
    let mut at: usize = cache
        .row_frame
        .header_widths()
        .iter()
        .map(|w| *w as usize)
        .sum();
    cache
        .col_widths
        .iter()
        .map(|w| {
            let end = (at + *w as usize).min(chars.len());
            let cell: String = chars[at.min(chars.len())..end].iter().collect();
            at = end;
            cell.trim().to_string()
        })
        .collect()
}

/// The index of the rule under the column headers: the one line that is
/// nothing else.
fn header_rule(lines: &[String]) -> usize {
    lines
        .iter()
        .position(|l| !l.trim().is_empty() && l.chars().all(|c| c == '─'))
        .expect("the header separator")
}

/// The buffer the widget paints, one string per line, borders stripped.
fn tui_lines(wb: &Workbook, cache: &GridCache) -> Vec<String> {
    let area = Rect::new(0, 0, 100, 30);
    let mut buf = Buffer::empty(area);
    let layout = GridLayout::new(&wb.model, wb.active_view());
    let view_name = wb.active_view.clone();
    let buffers = std::collections::HashMap::new();
    GridWidget::new(
        cache,
        ViewCursor::default(),
        &view_name,
        &layout,
        &AppMode::Normal,
        "",
        &buffers,
        None,
    )
    .render(area, &mut buf);

    let width = area.width as usize;
    buf.content()
        .chunks(width)
        // Strip the block's left and right border columns.
        .map(|row| {
            row[1..width - 1]
                .iter()
                .map(|c| c.symbol())
                .collect::<String>()
        })
        .collect()
}

/// What the browser client decides to draw, from a `Snapshot` of the same
/// cache — the real bootstrap path, not a hand-built client state.
fn browser_rows(cache: &GridCache) -> Vec<RenderRow> {
    browser_model(cache).rows
}

fn browser_model(cache: &GridCache) -> RenderModel {
    let mut client = improvise_wasm_client::init();
    client.bootstrap(Snapshot {
        view: ViewState::default(),
        seed: cache
            .seed()
            .into_iter()
            .map(improvise_protocol::Projection::Grid)
            .collect(),
    });
    client.model()
}

#[test]
fn the_two_front_ends_draw_the_same_row_header() {
    assert_row_headers_agree(&mut two_level_rows());
}

/// improvise-felo.6: Year > Quarter > Month in ONE category under a grouped one;
/// Y24 open two levels, Q2 and Y25 closed. Short names fit a TUI band cell.
fn a_date_hierarchy() -> Workbook {
    let mut m = Workbook::new("Test");
    m.add_category("Recipient").unwrap();
    m.add_category("Date").unwrap();
    m.add_item_in_group("Recipient", "Alice", "Fam").unwrap();
    m.add_item("Recipient", "Carol").unwrap();
    for (month, quarter) in [("Jan", "Q1"), ("Feb", "Q1"), ("Apr", "Q2"), ("Jan25", "Q9")] {
        m.add_item_in_group("Date", month, quarter).unwrap();
    }
    m.add_item("Date", "Undated").unwrap();
    let date = m.model.category_mut("Date").unwrap();
    for (quarter, year) in [("Q1", "Y24"), ("Q2", "Y24"), ("Q9", "Y25")] {
        date.add_group(improvise::model::category::Group::new(quarter).with_parent(year));
    }
    m.add_item("_Measure", "Revenue").unwrap();
    let view = m.active_view_mut();
    view.set_axis("Recipient", Axis::Row);
    view.set_axis("Date", Axis::Row);
    view.set_axis("_Measure", Axis::Column);
    view.set_expand_depth("Recipient", 1);
    view.set_group_fold(
        "Date",
        "Y24",
        GroupFold::Expanded(std::num::NonZeroUsize::new(2).unwrap()),
    );
    view.set_group_fold("Date", "Q2", GroupFold::Collapsed);
    for r in ["Alice", "Carol"] {
        for d in ["Jan", "Feb", "Apr", "Jan25", "Undated"] {
            m.model.set_cell(
                coord(&[("Recipient", r), ("Date", d), ("_Measure", "Revenue")]),
                CellValue::Number(1.0),
            );
        }
    }
    m
}

/// See `context/test-evidence/tui.md`.
#[test]
fn the_two_front_ends_draw_the_same_nested_hierarchy_on_rows() {
    let mut wb = a_date_hierarchy();
    let (_app, cache) = whole_grid(&mut wb);
    let groups: Vec<String> = browser_rows(&cache)
        .into_iter()
        .filter_map(|r| match r {
            RenderRow::Group { label, .. } => Some(label),
            RenderRow::Data { .. } => None,
        })
        .collect();
    assert_eq!(
        groups,
        ["Fam", "Y24", "Q1", "Q2", "Y25", "Y24", "Q1", "Q2", "Y25"],
        "precondition: a year AND its quarters head their runs, under each recipient"
    );
    assert_row_headers_agree(&mut wb);
}

/// The column side of the same hierarchy: the band paints each column's
/// innermost group, coalesced by header, at both ends.
#[test]
fn the_two_front_ends_draw_the_same_nested_hierarchy_on_columns() {
    let mut wb = a_date_hierarchy();
    wb.active_view_mut().transpose_axes();
    let (_app, cache) = whole_grid(&mut wb);
    let model = browser_model(&cache);
    let lines = tui_lines(&wb, &cache);
    let rule = header_rule(&lines);
    let levels = model.col_levels.len();
    let named: Vec<(Option<&str>, usize)> = model
        .col_groups
        .iter()
        .map(|g| (g.label.as_deref(), g.span))
        .collect();
    assert!(
        named.iter().any(|(l, _)| *l == Some("Q1")) && named.iter().any(|(l, _)| *l == Some("Y25")),
        "precondition: a quarter run and a folded year run: {named:?}"
    );
    let expected: Vec<String> = model
        .col_groups
        .iter()
        .flat_map(|g| {
            let head = match &g.label {
                Some(name) => format!("{} {name}", indicator(g.collapsed)),
                None => String::new(),
            };
            std::iter::once(head).chain(std::iter::repeat_n(String::new(), g.span - 1))
        })
        .collect();
    assert_eq!(
        &tui_header_cells(&lines[rule - levels - 1], &cache),
        &expected,
        "the TUI's group line and the browser's runs disagree"
    );
}

/// The row-header comparison, row by row: both ends, one cache.
fn assert_row_headers_agree(wb: &mut Workbook) {
    let (_app, cache) = whole_grid(wb);

    let tui = tui_row_headers(wb, &cache);
    let browser = browser_rows(&cache);

    assert_eq!(
        tui.len(),
        browser.len(),
        "the two ends drew a different number of rows\nTUI: {tui:?}\nbrowser: {browser:?}"
    );
    assert!(
        tui.len() > 4,
        "precondition: the fixture must have group headers AND several data \
         rows, or nothing here is being compared: {tui:?}"
    );

    for (i, (painted, decided)) in tui.iter().zip(browser.iter()).enumerate() {
        // A group label lands in the first sub-column, a data row's tuple one
        // per level, so the group arm compares the joined non-empty text.
        let painted_text = painted.join("").trim().to_string();
        match decided {
            // Glyph AND name: checking only the glyph would pass on any group
            // name whatsoever.
            RenderRow::Group { label, collapsed } => assert_eq!(
                painted_text,
                format!("{} {label}", indicator(*collapsed)),
                "row {i}: the two ends disagree about the group header"
            ),
            RenderRow::Data { labels, .. } => assert_eq!(
                painted, labels,
                "row {i}: the TUI painted {painted:?} and the browser decided \
                 {labels:?} — one of them re-derived the frame"
            ),
        }
    }
}

/// The TUI's glyph, spelled here so the comparison above is against what is
/// really painted rather than against a prefix test.
fn indicator(collapsed: bool) -> &'static str {
    match collapsed {
        true => "▶",
        false => "▼",
    }
}

/// The column side, separate because the row test drives ONE arm
/// (`doctrine(one_arm_of_a_symmetric_rule_is_evidence_about_that_arm_only)`).
#[test]
fn the_two_front_ends_draw_the_same_column_header() {
    let mut wb = two_level_rows();
    let (_app, cache) = whole_grid(&mut wb);
    let model = browser_model(&cache);
    let lines = tui_lines(&wb, &cache);
    let rule = header_rule(&lines);

    // The header block is the group line (when there is one) plus one line
    // per level, ending at the rule.
    let levels = model.col_levels.len();
    assert_eq!(levels, 2, "precondition: Month × _Measure is two levels");
    assert!(
        !model.col_groups.is_empty(),
        "precondition: Q1 groups two of the three months"
    );

    // Compared EXACTLY: a `contains` is one-directional and can see neither a
    // wrongly-blanked label nor one painted under the wrong column.
    for (level, labels) in model.col_levels.iter().enumerate() {
        assert_eq!(
            &tui_header_cells(&lines[rule - levels + level], &cache),
            labels,
            "level {level}: the TUI's header columns and the browser's \
             {labels:?} disagree — on suppression, on placement, or on both"
        );
    }

    // The spans partition the columns, and they are not all one column wide
    // — the fixture has a grouped run of two and an ungrouped run of one.
    let total: usize = model.col_groups.iter().map(|g| g.span).sum();
    assert_eq!(
        total,
        cache.col_frame.len(),
        "the spans must cover every column, or a colspan layout leaves a hole"
    );
    let named: Vec<(Option<&str>, usize)> = model
        .col_groups
        .iter()
        .map(|g| (g.label.as_deref(), g.span))
        .collect();
    // improvise-gd83: MEMBERSHIP, not nearest-preceding. Sep is ungrouped, so
    // the run ends before it and resumes under the next measure's Q1 header.
    assert_eq!(
        named,
        vec![(Some("Q1"), 2), (None, 1), (Some("Q1"), 2), (None, 1)],
        "the two Q1 runs are separated by the ungrouped Sep; a run that \
         swallowed it would be `expand_category` leaking a group across its \
         own boundary (see `AxisFrame::group_of`)"
    );
    assert!(
        named.iter().any(|(label, _)| label.is_none()),
        "precondition: the fixture must contain an UNGROUPED column, or this \
         test cannot see a leaked group at all"
    );

    // improvise-8qlr: the TUI's group line, compared EXACTLY. A `contains`
    // passes while the TUI labels every column, which is a different grid.
    let group_line = &lines[rule - levels - 1];
    let expected: Vec<String> = model
        .col_groups
        .iter()
        .flat_map(|g| {
            let head = match &g.label {
                Some(name) => format!("{} {name}", indicator(g.collapsed)),
                None => String::new(),
            };
            std::iter::once(head).chain(std::iter::repeat_n(String::new(), g.span - 1))
        })
        .collect();
    assert_eq!(
        &tui_header_cells(group_line, &cache),
        &expected,
        "the TUI's group line and the browser's runs disagree — one of them \
         coalesces the runs itself instead of asking `group_runs`"
    );
}

/// `two_level_rows` without `Sep`, so the two `Q1` runs ABUT. The existing
/// fixture is saved by the ungrouped month between them — improvise-h0iv.
fn abutting_column_groups() -> Workbook {
    let mut m = two_level_rows();
    m.remove_item("Month", "Sep");
    m
}

/// improvise-h0iv, end to end: two `Q1` runs under two measures are two spans,
/// and both ends draw them. See `context/test-evidence/tui.md`.
#[test]
fn two_abutting_runs_of_one_group_name_are_two_spans_at_both_ends() {
    let mut wb = abutting_column_groups();
    let (_app, cache) = whole_grid(&mut wb);
    let model = browser_model(&cache);
    let lines = tui_lines(&wb, &cache);
    let rule = header_rule(&lines);
    let levels = model.col_levels.len();

    let named: Vec<(Option<&str>, usize)> = model
        .col_groups
        .iter()
        .map(|g| (g.label.as_deref(), g.span))
        .collect();
    assert!(
        named.iter().all(|(label, _)| label.is_some()),
        "precondition: NOTHING ungrouped may separate the runs, which is the \
         whole difference from the fixture above: {named:?}"
    );
    assert_eq!(
        named,
        vec![(Some("Q1"), 2), (Some("Q1"), 2)],
        "one span of four draws a single header across the measure boundary"
    );

    let group_line = &lines[rule - levels - 1];
    let expected: Vec<String> = model
        .col_groups
        .iter()
        .flat_map(|g| {
            let head = match &g.label {
                Some(name) => format!("{} {name}", indicator(g.collapsed)),
                None => String::new(),
            };
            std::iter::once(head).chain(std::iter::repeat_n(String::new(), g.span - 1))
        })
        .collect();
    assert_eq!(
        &tui_header_cells(group_line, &cache),
        &expected,
        "the TUI draws one group line and the browser decided another"
    );
}

/// improvise-0o6x: a group FIRST on its axis. Separate from `two_level_rows`,
/// which orders Carol first to dodge this case on purpose.
fn leading_group_rows() -> Workbook {
    let mut m = Workbook::new("Test");
    m.add_category("Recipient").unwrap();
    m.add_item_in_group("Recipient", "Alice", "Fam").unwrap();
    m.add_item_in_group("Recipient", "Bob", "Fam").unwrap();
    m.active_view_mut().set_expand_depth("Recipient", 1);
    m.add_item("Recipient", "Carol").unwrap();
    m.add_item("_Measure", "Revenue").unwrap();
    m.active_view_mut().set_axis("Recipient", Axis::Row);
    m.active_view_mut().set_axis("_Measure", Axis::Column);
    for r in ["Alice", "Bob", "Carol"] {
        m.model.set_cell(
            coord(&[("Recipient", r), ("_Measure", "Revenue")]),
            CellValue::Number(1.0),
        );
    }
    m
}

/// A collapsed group at position zero is otherwise a trap: its rows are hidden
/// and its header is the only affordance. context/test-evidence/tui.md.
#[test]
fn a_group_header_first_on_its_axis_reaches_both_front_ends() {
    for collapse in [false, true] {
        let mut wb = leading_group_rows();
        if collapse {
            wb.active_view_mut()
                .toggle_group_collapse("Recipient", &["Fam"]);
        }
        let (_app, cache) = whole_grid(&mut wb);

        assert!(
            matches!(cache.row_frame.entries.first(), Some(FrameEntry::Group(g)) if g.name == "Fam"),
            "precondition (collapse={collapse}): the frame must LEAD with the \
             header, or body_from has nothing at position zero to drop"
        );

        let browser = browser_rows(&cache);
        assert!(
            matches!(browser.first(), Some(RenderRow::Group { label, .. }) if label == "Fam"),
            "the browser dropped the leading group header: {browser:?}"
        );

        let painted = tui_row_headers(&wb, &cache);
        assert_eq!(
            painted.first().map(|r| r.join("").trim().to_string()),
            Some(format!("{} Fam", indicator(collapse))),
            "the TUI dropped the leading group header: {painted:?}"
        );
    }
}

/// The bug's own words, separate because the agreement above would also hold
/// if *both* ends started slash-joining.
#[test]
fn neither_front_end_produces_a_slash_joined_label() {
    let mut wb = two_level_rows();
    let (_app, cache) = whole_grid(&mut wb);

    for row in browser_rows(&cache) {
        for label in row.labels() {
            assert!(
                !label.contains('/'),
                "the browser drew the joined label {label:?}"
            );
        }
    }
    for painted in tui_row_headers(&wb, &cache) {
        for label in painted {
            assert!(
                !label.contains('/'),
                "the TUI painted the joined label {label:?}"
            );
        }
    }
}

/// The collapse state crosses as a boolean, not a glyph (gotcha 26). BOTH
/// states, because a hard-wired `false` would pass the first half.
#[test]
fn the_collapse_state_crosses_as_a_fact_not_a_glyph() {
    for collapse in [false, true] {
        let mut wb = two_level_rows();
        if collapse {
            wb.active_view_mut()
                .toggle_group_collapse("Recipient", &["Family"]);
        }
        let (_app, cache) = whole_grid(&mut wb);

        let groups: Vec<(String, bool)> = browser_rows(&cache)
            .into_iter()
            .filter_map(|r| match r {
                RenderRow::Group { label, collapsed } => Some((label, collapsed)),
                RenderRow::Data { .. } => None,
            })
            .collect();
        assert!(
            !groups.is_empty(),
            "precondition (collapse={collapse}): a collapsed group still owes \
             the user a header to expand again"
        );
        for (label, collapsed) in groups {
            assert_eq!(label, "Family");
            assert_eq!(collapsed, collapse, "the frame states the view's answer");
        }
    }
}