# Tests for the Buffer class included in usb.device.impl
#
# The easiest way to run this is using unix port. From the top-level usb-device directory,
# run as:
#
# $ micropython -m tests.test_impl_buffer
#
import micropython
from usb.device import impl
from impl import Buffer

if not hasattr(impl.machine, "disable_irq"):
    # Inject a fake machine module which allows testing on the unix port, and as
    # a bonus have tests fail if the buffer allocates inside a critical section.
    class FakeMachine:
        def disable_irq(self):
            return micropython.heap_lock()

        def enable_irq(self, was_locked):
            if not was_locked:
                micropython.heap_unlock()

    impl.machine = FakeMachine()


b = Buffer(16)

# Check buffer is empty
assert b.readable() == 0
assert b.writable() == 16

# Single write then read
w = b.pend_write()
assert len(w) == 16
w[:8] = b"12345678"
b.finish_write(8)

# Empty again
assert b.readable() == 8
assert b.writable() == 8

r = b.pend_read()
assert len(r) == 8
assert r == b"12345678"
b.finish_read(8)

# Empty buffer again
assert b.readable() == 0
assert b.writable() == 16

# Single write then split reads
b.write(b"abcdefghijklmnop")
assert b.writable() == 0  # full buffer

r = b.pend_read()
assert r == b"abcdefghijklmnop"
b.finish_read(2)

r = b.pend_read()
assert r == b"cdefghijklmnop"
b.finish_read(3)

# write to end of buffer
b.write(b"AB")

r = b.pend_read()
assert r == b"fghijklmnopAB"

# write while a read is pending
b.write(b"XY")

# previous pend_read() memoryview should be the same
assert r == b"fghijklmnopAB"

b.finish_read(4)
r = b.pend_read()
assert r == b"jklmnopABXY"  # four bytes consumed from head, one new byte at tail

# read while a write is pending
w = b.pend_write()
assert len(w) == 5
r = b.pend_read()
assert len(r) == 11
b.finish_read(3)
w[:2] = b"12"
b.finish_write(2)

# Expected final state of buffer
tmp = bytearray(b.readable())
assert b.readinto(tmp) == len(tmp)
assert tmp == b"mnopABXY12"

# Now buffer is empty again
assert b.readable() == 0
assert b.readinto(tmp) == 0
assert b.writable() == 16

print("All Buffer tests passed")