import importlib
import os.path
import re
import sys
import tempfile

import testlib

class Hart:
    # XLEN of the hart. May be overridden with --32 or --64 command line
    # options.
    xlen = 0

    # Will be autodetected (by running ExamineTarget) if left unset. Set to
    # save a little time.
    misa = None

    # Path to linker script relative to the .py file where the target is
    # defined. Defaults to <name>.lds.
    link_script_path = None

    # Implements dmode in tdata1 as described in the spec. Harts that need
    # this value set to False are not compliant with the spec (but still usable
    # as long as running code doesn't try to mess with triggers set by an
    # external debugger).
    honors_tdata1_hmode = True

    # Address where a r/w/x block of RAM starts, together with its size.
    ram = None
    ram_size = None

    # Address where we expect memory accesses to fail, usually because there is
    # no device mapped to that location.
    bad_address = None

    # Number of instruction triggers the hart supports.
    instruction_hardware_breakpoint_count = 0

    # Defaults to target-<index>
    name = None

    # When reset, the PC must be at one of the values listed here.
    # This is a list because on some boards the reset vector depends on
    # jumpers.
    reset_vectors = []

    def __init__(self, system=None):
        """system is set to an identifier of the system this hart belongs to.
        Harts within the same system are assumed to share memory, and to have
        unique hartids within that system.  So for most cases the default
        value of None is fine."""
        self.system = system

    def extensionSupported(self, letter):
        # target.misa is set by testlib.ExamineTarget
        if self.misa:
            return self.misa & (1 << (ord(letter.upper()) - ord('A')))
        return False

class Target:
    # pylint: disable=too-many-instance-attributes

    # List of Hart object instances, one for each hart in the target.
    harts = []

    # Name of the target. Defaults to the name of the class.
    name = None

    # GDB remotetimeout setting.
    timeout_sec = 2

    # Timeout waiting for the server to start up. This is different than the
    # GDB timeout, which is how long GDB waits for commands to execute.
    # The server_timeout is how long this script waits for the server to be
    # ready for GDB connections.
    server_timeout_sec = 60

    # Path to OpenOCD configuration file relative to the .py file where the
    # target is defined. Defaults to <name>.cfg.
    openocd_config_path = None

    # List of commands that should be executed in gdb after connecting but
    # before starting the test.
    gdb_setup = []

    # Supports mtime at 0x2004000
    supports_clint_mtime = True

    # Implements custom debug registers like spike does. It seems unlikely any
    # hardware will every do that.
    implements_custom_test = False

    # When true it indicates that reading invalid memory doesn't return an error
    invalid_memory_returns_zero = False

    # Supports simultaneous resume through hasel.
    support_hasel = True

    # Tests whose names are mentioned in this list will be skipped and marked
    # as not applicable. This is a crude mechanism that can be handy, but in
    # general it's better to define some property like those above that
    # describe behavior of this target, and tests can use that to decide
    # whether they are applicable or not.
    skip_tests = []

    # Set False if semihosting should not be tested in this configuration,
    # because it doesn't work and isn't expected to work.
    test_semihosting = True

    # Set False if manual hwbps (breakpoints set by directly writing tdata*)
    # isn't supposed to work.
    support_manual_hwbp = True

    # Set False if memory sampling is not supported due to OpenOCD
    # limitation/hardware support.
    support_memory_sampling = True

    # Relative path to a FreeRTOS binary compiled from the spike demo project
    # in https://github.com/FreeRTOS/FreeRTOS.
    freertos_binary = None

    # Internal variables:
    directory = None
    temporary_files = []

    def __init__(self, path, parsed):
        # Path to module.
        self.path = path
        self.directory = os.path.dirname(path)
        self.server_cmd = parsed.server_cmd
        self.sim_cmd = parsed.sim_cmd
        self.temporary_binary = None
        self.compiler_supports_v = True
        Target.isolate = parsed.isolate
        if not self.name:
            self.name = type(self).__name__
        # Default OpenOCD config file to <name>.cfg
        if not self.openocd_config_path:
            self.openocd_config_path = "%s.cfg" % self.name
        self.openocd_config_path = os.path.join(self.directory,
                self.openocd_config_path)
        for i, hart in enumerate(self.harts):
            hart.index = i
            if not hasattr(hart, 'id'):
                hart.id = i
            if not hart.name:
                hart.name = "%s-%d" % (self.name, i)
            # Default link script to <name>.lds
            if not hart.link_script_path:
                hart.link_script_path = "%s.lds" % self.name
            hart.link_script_path = os.path.join(self.directory,
                    hart.link_script_path)

    def create(self):
        """Create the target out of thin air, eg. start a simulator."""

    def server(self, test):
        """Start the debug server that gdb connects to, eg. OpenOCD."""
        return testlib.Openocd(server_cmd=self.server_cmd,
                config=self.openocd_config_path,
                timeout=self.server_timeout_sec,
                freertos=test.freertos())

    def do_compile(self, hart, *sources):
        binary_name = "%s_%s-%d" % (
                self.name,
                os.path.basename(os.path.splitext(sources[0])[0]),
                hart.xlen)
        if Target.isolate:
            self.temporary_binary = tempfile.NamedTemporaryFile(
                    prefix=binary_name + "_")
            binary_name = self.temporary_binary.name
            Target.temporary_files.append(self.temporary_binary)

        args = list(sources) + [
                "programs/entry.S", "programs/init.c",
                "-DNHARTS=%d" % len(self.harts),
                "-I", "../env",
                "-T", hart.link_script_path,
                "-nostartfiles",
                "-mcmodel=medany",
                "-DXLEN=%d" % hart.xlen,
                "-o", binary_name]

        if hart.extensionSupported('e'):
            args.append("-march=rv32e")
            args.append("-mabi=ilp32e")
            args.append("-DRV32E")
        else:
            march = "rv%dima" % hart.xlen
            for letter in "fdc":
                if hart.extensionSupported(letter):
                    march += letter
            if hart.extensionSupported("v") and self.compiler_supports_v:
                march += "v"
            args.append("-march=%s" % march)
            if hart.xlen == 32:
                args.append("-mabi=ilp32")
            else:
                args.append("-mabi=lp%d" % hart.xlen)

        testlib.compile(args)
        return binary_name

    def compile(self, hart, *sources):
        while True:
            try:
                return self.do_compile(hart, *sources)
            except testlib.CompileError as e:
                # If the compiler doesn't support V, disable it from the
                # current configuration. Eventually all gcc branches will
                # support V, but we're not there yet.
                m = re.search(r"Error: cannot find default versions of the "
                        r"ISA extension `(\w)'", e.stderr.decode())
                if m and m.group(1) in "v":
                    extension = m.group(1)
                    print("Disabling extension %r because the "
                            "compiler doesn't support it." % extension)
                    self.compiler_supports_v = False
                else:
                    raise

def add_target_options(parser):
    parser.add_argument("target", help=".py file that contains definition for "
            "the target to test with.")
    parser.add_argument("--sim_cmd",
            help="The command to use to start the actual target (e.g. "
            "simulation)", default="spike")
    parser.add_argument("--server_cmd",
            help="The command to use to start the debug server (e.g. OpenOCD)")

    xlen_group = parser.add_mutually_exclusive_group()
    xlen_group.add_argument("--32", action="store_const", const=32,
            dest="xlen", default=0, help="Force the target to be 32-bit.")
    xlen_group.add_argument("--64", action="store_const", const=64,
            dest="xlen", default=0, help="Force the target to be 64-bit.")

    parser.add_argument("--isolate", action="store_true",
            help="Try to run in such a way that multiple instances can run at "
            "the same time. This may make it harder to debug a failure if it "
            "does occur.")

def target(parsed):
    directory = os.path.dirname(parsed.target)
    filename = os.path.basename(parsed.target)
    module_name = os.path.splitext(filename)[0]

    sys.path.append(directory)
    module = importlib.import_module(module_name)
    found = []
    for name in dir(module):
        definition = getattr(module, name)
        if isinstance(definition, type) and issubclass(definition, Target):
            found.append(definition)
    assert len(found) == 1, "%s does not define exactly one subclass of " \
            "targets.Target" % parsed.target

    t = found[0](parsed.target, parsed)
    assert t.harts, "%s doesn't have any harts defined!" % t.name
    if parsed.xlen > 0:
        for h in t.harts:
            if h.xlen == 0:
                h.xlen = parsed.xlen
            elif h.xlen != parsed.xlen:
                raise Exception("The target hart specified an XLEN of %d, but "\
                        "the command line specified an XLEN of %d. They must "\
                        "match." % (h.xlen, parsed.xlen))

    return t