import os
import sys

import imagej
import scyjava

from pathlib import Path


# Credit: https://stackoverflow.com/a/640431/1207769
from ctypes import POINTER, c_int, cast, pythonapi
def in_interactive_inspect_mode():
    """Whether '-i' option is present or PYTHONINSPECT is not empty."""
    if os.environ.get('PYTHONINSPECT'): return True
    iflag_ptr = cast(pythonapi.Py_InteractiveFlag, POINTER(c_int))
    #NOTE: in Python 2.6+ ctypes.pythonapi.Py_InspectFlag > 0
    #      when PYTHONINSPECT set or '-i' is present
    return iflag_ptr.contents.value != 0


def launch_fiji():
    # Discern app directory.
    app_dir = Path(__file__).parent

    # Find the divider argument.
    divider = "--"
    try:
        div_index = sys.argv.index(divider)
    except AttributeError:
        div_index = -1

    # Validate argument syntax.
    if len(sys.argv) < 4 or div_index < 0 or div_index > len(sys.argv) - 2:
        print(
            "Usage: fiji.py path-to-libjvm [jvm-arg1 ... jvm-argN] "
            f"{divider} main-class [main-arg1 ... main-argN]"
        )
        sys.exit(1)

    # Parse out the arguments.
    libjvm_path = sys.argv[1]
    jvm_args = sys.argv[2:div_index]
    main_class = sys.argv[div_index+1]
    main_args = sys.argv[div_index+2:]

    # Isolate any classpath arguments.
    classpath_prefix = "-Djava.class.path="
    classpath_args = [arg for arg in jvm_args if arg.startswith(classpath_prefix)]
    jvm_args = [arg for arg in jvm_args if arg not in classpath_args]

    # Combine classpaths into a single list.
    classpath = [
        el
        for arg in classpath_args
        for el in arg[len(classpath_prefix):].split(os.path.pathsep)
    ]

    # Set JAVA_HOME to encourage use of the intended JVM.
    # HACK: Assume the JVM library is nestled beneath a `lib` folder.
    p = Path(libjvm_path).absolute().parent
    while p.name != "lib" and p != p.parent:
        p = p.parent
    os.environ["JAVA_HOME"] = str(p.parent)

    #scyjava.config.add_classpath(*scyjava.config.find_jars(app_dir))
    scyjava.config.add_classpath(*classpath)
    scyjava.start_jvm(jvm_args)

    # Initialize ImageJ, wrapping the local Fiji directory.
    # NB: It's OK to pass `interactive` always, because when the
    # --headless flag is given, Fiji still ends up in headless mode.
    ij = imagej.init(app_dir, mode="interactive")

    # Let the Script Editor support Python via scyjava/PyImageJ.
    scyjava.enable_python_scripting(ij.context())

    # Show the user interface.
    ij.ui().showUI()

    return ij


ij = launch_fiji()

if not in_interactive_inspect_mode():
    # We're not in interactive mode, so we need to block
    # to prevent the entire process from shutting down.
    from time import sleep
    while True:
        sleep(0.1)