// Data schema and channel helpers.
(function (root) {
    const chartUtils = root.chartUtils;
    const schema = chartUtils.schema;

    schema.normalizeUnit = unit => {
        if (unit == null) return "";
        const text = String(unit).trim();
        const lower = text.toLowerCase();
        return ["", "none", "null", "nan", "undefined", "n/a", "na"].includes(lower) ? "" : text;
    };

    schema.columns = jsonData => {
        const columns = jsonData && jsonData.data && jsonData.data.columns;
        return Array.isArray(columns) ? columns : [];
    };

    const buildChannel = (column, role, index, fallbackKey) => {
        const key = column && column.name != null ? column.name : fallbackKey;
        const rawLabel = column
            ? (column.label || column.display_name || column.name || fallbackKey || "")
            : (fallbackKey || "");
        const unit = schema.normalizeUnit(column && column.unit);
        const description = column && column.description ? column.description : rawLabel;
        const displayName = column && column.display_name ? column.display_name : rawLabel;
        return {
            role: column && column.role != null ? column.role : role,
            index: index == null ? -1 : index,
            key: key || "",
            type: column && column.data_type ? column.data_type : "",
            unit,
            rawLabel,
            description,
            displayName,
            label: unit ? `${rawLabel} (${unit})` : rawLabel,
            raw: column || null,
        };
    };

    schema.channel = (jsonData, role, options = {}) => {
        const columns = schema.columns(jsonData);
        let index = columns.findIndex(column => column.role === role);
        if (index < 0 && options.fallbackIndex != null) {
            index = options.fallbackIndex;
        }
        const column = index >= 0 ? columns[index] : null;
        const fallbackKey = Object.prototype.hasOwnProperty.call(options, "fallbackKey")
            ? options.fallbackKey
            : role;
        return buildChannel(column, role, index, fallbackKey);
    };

    schema.channelByKey = (jsonData, key, options = {}) => {
        const columns = schema.columns(jsonData);
        let index = columns.findIndex(column => column.name === key);
        if (index < 0 && options.fallbackIndex != null) {
            index = options.fallbackIndex;
        }
        const column = index >= 0 ? columns[index] : null;
        const fallbackKey = Object.prototype.hasOwnProperty.call(options, "fallbackKey")
            ? options.fallbackKey
            : key;
        return buildChannel(column, options.role || (column && column.role) || "", index, fallbackKey);
    };

    schema.column = (columns, index, options = {}) => {
        const list = Array.isArray(columns) ? columns : [];
        const column = index >= 0 ? list[index] : null;
        return buildChannel(column, options.role || (column && column.role) || "", index, options.fallbackKey);
    };

    schema.columnField = (columns, index, fallbackKey = "", options = {}) => (
        schema.column(columns, index, { ...options, fallbackKey }).key
    );

    schema.field = (jsonData, index, fallbackKey = "", options = {}) => (
        schema.columnField(schema.columns(jsonData), index, fallbackKey, options)
    );

    schema.channels = (jsonData, spec) => {
        const result = {};
        Object.keys(spec || {}).forEach(role => {
            result[role] = schema.channel(jsonData, role, spec[role]);
        });
        return result;
    };

})(globalThis);