// ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
// ┃ ██████ ██████ ██████       █      █      █      █      █ █▄  ▀███ █       ┃
// ┃ ▄▄▄▄▄█ █▄▄▄▄▄ ▄▄▄▄▄█  ▀▀▀▀▀█▀▀▀▀▀ █ ▀▀▀▀▀█ ████████▌▐███ ███▄  ▀█ █ ▀▀▀▀▀ ┃
// ┃ █▀▀▀▀▀ █▀▀▀▀▀ █▀██▀▀ ▄▄▄▄▄ █ ▄▄▄▄▄█ ▄▄▄▄▄█ ████████▌▐███ █████▄   █ ▄▄▄▄▄ ┃
// ┃ █      ██████ █  ▀█▄       █ ██████      █      ███▌▐███ ███████▄ █       ┃
// ┣━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┫
// ┃ Copyright (c) 2017, the Perspective Authors.                              ┃
// ┃ ╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌ ┃
// ┃ This file is part of the Perspective library, distributed under the terms ┃
// ┃ of the [Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0). ┃
// ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛

import type { CartesianChart } from "./cartesian";

/**
 * Build the per-row tooltip for a point-style glyph (scatter, gradient
 * heatmap). Resolves the source arrow row via the chart's lazy row
 * fetcher, then surfaces every non-null column under the (split-aware)
 * prefix filter formatted by column type.
 *
 * Returns `[]` when the chart has no row-index mirror or no fetcher;
 * callers should fall back to a geometry-only tooltip in that case.
 */
export async function buildPointRowTooltipLines(
    chart: CartesianChart,
    flatIdx: number,
): Promise<string[]> {
    const lines: string[] = [];
    if (!chart._rowIndexData || !chart._lazyRows) {
        return lines;
    }

    const rowIdx = chart._rowIndexData[flatIdx];
    if (rowIdx < 0) {
        return lines;
    }

    if (chart._splitGroups.length > 0 && chart._seriesCapacity > 0) {
        const seriesIdx = Math.floor(flatIdx / chart._seriesCapacity);
        const sg = chart._splitGroups[seriesIdx];
        if (sg?.prefix) {
            lines.push(sg.prefix);
        }
    }

    const row = await chart._lazyRows.fetchRow(rowIdx);

    const prefixFilter =
        chart._splitGroups.length > 0 && chart._seriesCapacity > 0
            ? (chart._splitGroups[Math.floor(flatIdx / chart._seriesCapacity)]
                  ?.prefix ?? null)
            : null;

    for (const [colName, value] of row) {
        if (value === null || value === undefined) {
            continue;
        }

        let displayName = colName;
        if (prefixFilter !== null) {
            const expected = `${prefixFilter}|`;
            if (!colName.startsWith(expected)) {
                continue;
            }

            displayName = colName.substring(expected.length);
        } else if (colName.includes("|")) {
            continue;
        }

        if (typeof value === "number") {
            const formatted = chart.getColumnFormatter(colName, "value")(value);
            lines.push(`${displayName}: ${formatted}`);
        } else {
            lines.push(`${displayName}: ${value}`);
        }
    }

    return lines;
}
