CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Income Statement [Abstract]
Revenues	$ 95,868	$ 59,702	$ 53,603
Cost of revenues	66,561	55,770	46,379
Gross profit	29,307	3,932	7,224
Operating expenses:
Selling, general and administrative	17,064	14,517	12,846
Loss on lease termination	0	355	0
Total operating expenses	17,064	14,872	12,846
Operating income (loss)	12,243	(10,940)	(5,622)
Interest and other income, net	133	482	293
Interest expense	(1,164)	(8)	(11)
Income (loss) from continuing operations before income taxes	11,212	(10,466)	(5,340)
Income tax benefit	0	0	284
Income (loss) from continuing operations, net of tax	11,212	(10,466)	(5,056)
Income from discontinued operations, net of tax	0	0	841
Net income (loss)	11,212	(10,466)	(4,215)
Comprehensive income (loss)	11,212	(10,466)	(4,215)
Series E preferred stock accumulated dividends	(4,455)	(4,686)	(4,686)
Impact of Series E preferred stock redemption	(3,439)	0	0
Net income (loss) attributable to common stockholders	$ 3,318	$ (15,152)	$ (8,901)
Net income (loss) per share attributable to common stockholders, basic and diluted - Continuing operations	$ 0.06	$ (0.27)	$ (0.17)
Net income (loss) per share attributable to common stockholders, basic and diluted - Discontinued operations	0.00	0.00	0.01
Earnings per share	$ 0.06	$ (0.27)	$ (0.16)
Weighted average common shares outstanding - Basic	58,222	56,326	55,981
Weighted average common shares outstanding - Diluted	59,426	56,326	55,981