import importlib
import os.path
import sys
import tempfile

import testlib

class Hart(object):
    # 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

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

class Target(object):
    # 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

    # 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
        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."""
        pass

    def server(self):
        """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)

    def 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)
        march = "rv%dima" % hart.xlen
        for letter in "fdc":
            if hart.extensionSupported(letter):
                march += letter
        testlib.compile(sources +
                ("programs/entry.S", "programs/init.c",
                    "-DNHARTS=%d" % len(self.harts),
                    "-I", "../env",
                    "-march=%s" % march,
                    "-T", hart.link_script_path,
                    "-nostartfiles",
                    "-mcmodel=medany",
                    "-DXLEN=%d" % hart.xlen,
                    "-o", binary_name),
                xlen=hart.xlen)
        return binary_name

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
