import hashlib
import re
import shlex
import sys

start = re.escape("/*[")
end = re.escape("]*/")

start_line    = re.compile(start + "(?P<dsl_name>\w+) input\\]")
body_prefix   = ""
stop_line     = re.compile("\\[(?P<dsl_name>\w+) start generated code" + end)
checksum_line = re.compile(start + "(?P<dsl_name>\w+) end generated code: (?P<arguments>.+)" + end)

state_verbatim       = 'verbatim'
state_clinic_input  = 'clinic_input'
state_clinic_output = 'clinic_output'



def compute_checksum(input, length=None):
    input = input or ''
    s = hashlib.sha1(input.encode('utf-8')).hexdigest()
    if length:
        s = s[:length]
    return s


def fail(*a):
    print("Error in", repr(filename), "on line", str(line_number) + ":")
    print(*a)
    sys.exit(-1)

def reset():
    global input
    global output
    global state
    input = []
    output = []
    state = state_verbatim



input = output = state = None

for filename in sys.argv[1:]:
    reset()
    with open(filename, "rt") as f:
        for line_number, line in enumerate(f.read().splitlines(True), 1):
            if state == state_verbatim:
                match = start_line.match(line)
                if match:
                    dsl_name = match.group('dsl_name')
                    state = state_clinic_input
            elif state == state_clinic_input:
                match = stop_line.match(line)
                if match:
                    got = match.group('dsl_name')
                    if got != dsl_name:
                        fail("Error: mismatched dsl name!  Expected", repr(dsl_name), "but got", repr(got))
                    state = state_clinic_output
                else:
                    input.append(line)
            elif state == state_clinic_output:
                match = checksum_line.match(line)
                if match:
                    got = match.group('dsl_name')
                    if got != dsl_name:
                        fail("Error: mismatched dsl name!  Expected", repr(dsl_name), "but got", repr(got))
                    # print("found block:", repr(input[:5]), repr(output[:5]))
                    d = {}
                    for field in shlex.split(match.group('arguments')):
                        name, equals, value = field.partition('=')
                        if not equals:
                            fail("Malformed arguments to checksum line")
                        d[name.strip()] = value.strip()
                    if 'checksum' in d:
                        checksum = d['checksum']
                        input_checksum = None
                    else:
                        checksum = d['output']
                        input_checksum = d['input']
                    output = ''.join(output)
                    computed = compute_checksum(output, len(checksum))
                    # print("checksum", checksum, "computed", computed)
                    if checksum != computed:
                        fail("Output checksum mismatch!  Someone modified the output text!")
                    if input_checksum:
                        input = ''.join(input)
                        computed = compute_checksum(input, len(input_checksum))
                        # print("input_checksum", input_checksum, "computed", computed)
                        if input_checksum != computed:
                            fail("Input checksum mismatch!  Clinic generated code is out of date!")

                    reset()
                    # print()
                else:
                    output.append(line)