export class AttributeRequirementsController {
	private _attribute_names: Set<string> | undefined;
	constructor() {}

	reset() {
		if (this._attribute_names) {
			this._attribute_names.clear();
		}
	}
	assign_attributes_lines(): string {
		if (this._attribute_names) {
			const lines: string[] = [];
			this._attribute_names?.forEach((attribute_name: string) => {
				lines.push(AttributeRequirementsController.assign_attribute_line(attribute_name));
			});
			return lines.join(';\n');
		} else {
			return '';
		}
	}
	assign_arrays_lines(): string {
		if (this._attribute_names) {
			const lines: string[] = [];
			this._attribute_names?.forEach((attribute_name: string) => {
				lines.push(AttributeRequirementsController.assign_item_size_line(attribute_name));
				lines.push(AttributeRequirementsController.assign_array_line(attribute_name));
			});
			return lines.join(';\n');
		} else {
			return '';
		}
	}
	attribute_presence_check_line(): string {
		if (this._attribute_names) {
			const var_names: string[] = [];
			this._attribute_names?.forEach((attribute_name: string) => {
				const var_name = AttributeRequirementsController.var_attribute(attribute_name);
				var_names.push(var_name);
			});
			if (var_names.length > 0) {
				return var_names.join(' && ');
			}
		}
		// TODO: add test that a Point Sop can take an expression that does not require attributes
		return 'true';
	}

	add(attribute_name: string) {
		this._attribute_names = this._attribute_names || new Set<string>();
		this._attribute_names.add(attribute_name);
	}

	static assign_attribute_line(attribute_name: string) {
		const var_attribute = this.var_attribute(attribute_name);
		return `const ${var_attribute} = entities[0].geometry().attributes['${attribute_name}']`;
	}
	static assign_item_size_line(attribute_name: string) {
		const var_attribute = this.var_attribute(attribute_name);
		const var_attribute_size = this.var_attribute_size(attribute_name);
		return `const ${var_attribute_size} = ${var_attribute}.itemSize`;
	}
	static assign_array_line(attribute_name: string) {
		const var_attribute = this.var_attribute(attribute_name);
		const var_array = this.var_array(attribute_name);
		return `const ${var_array} = ${var_attribute}.array`;
	}

	static var_attribute(attribute_name: string) {
		return `attrib_${attribute_name}`;
	}
	static var_attribute_size(attribute_name: string) {
		return `attrib_size_${attribute_name}`;
	}
	static var_array(attribute_name: string) {
		return `array_${attribute_name}`;
	}
	var_attribute_size(attribute_name: string) {
		return AttributeRequirementsController.var_attribute_size(attribute_name);
	}
	var_array(attribute_name: string) {
		return AttributeRequirementsController.var_array(attribute_name);
	}
}