# This script is an example of how you can run blender from the command line
# (in background mode with no interface) to automate tasks, in this example it
# creates a text object, camera and light, then renders and/or saves it.
# This example also shows how you can parse command line options to scripts.
#
# Example usage for this test.
#  blender --background --factory-startup --python $HOME/background_job.py -- \
#          --text="Hello World" \
#          --render="/tmp/hello" \
#          --save="/tmp/hello.blend"
#
# Notice:
# '--factory-startup' is used to avoid the user default settings from
#                     interfering with automated scene generation.
#
# '--' causes blender to ignore all following arguments so python can use them.
#
# See blender --help for details.


import bpy


def example_function(text, save_path, render_path):
    # Clear existing objects.
    bpy.ops.wm.read_factory_settings(use_empty=True)

    scene = bpy.context.scene

    txt_data = bpy.data.curves.new(name="MyText", type='FONT')

    # Text Object
    txt_ob = bpy.data.objects.new(name="MyText", object_data=txt_data)
    scene.collection.objects.link(txt_ob)   # add the data to the scene as an object
    txt_data.body = text         # the body text to the command line arg given
    txt_data.align_x = 'CENTER'  # center text

    # Camera
    cam_data = bpy.data.cameras.new("MyCam")
    cam_ob = bpy.data.objects.new(name="MyCam", object_data=cam_data)
    scene.collection.objects.link(cam_ob)  # instance the camera object in the scene
    scene.camera = cam_ob       # set the active camera
    cam_ob.location = 0.0, 0.0, 10.0

    # Light
    light_data = bpy.data.lights.new("MyLight", 'POINT')
    light_ob = bpy.data.objects.new(name="MyLight", object_data=light_data)
    scene.collection.objects.link(light_ob)
    light_ob.location = 2.0, 2.0, 5.0

    bpy.context.view_layer.update()

    if save_path:
        bpy.ops.wm.save_as_mainfile(filepath=save_path)

    if render_path:
        render = scene.render
        render.use_file_extension = True
        render.filepath = render_path
        bpy.ops.render.render(write_still=True)


def main():
    import sys       # to get command line args
    import argparse  # to parse options for us and print a nice help message

    # get the args passed to blender after "--", all of which are ignored by
    # blender so scripts may receive their own arguments
    argv = sys.argv

    if "--" not in argv:
        argv = []  # as if no args are passed
    else:
        argv = argv[argv.index("--") + 1:]  # get all args after "--"

    # When --help or no args are given, print this help
    usage_text = (
        "Run blender in background mode with this script:"
        "  blender --background --python " + __file__ + " -- [options]"
    )

    parser = argparse.ArgumentParser(description=usage_text)

    # Example utility, add some text and renders or saves it (with options)
    # Possible types are: string, int, long, choice, float and complex.
    parser.add_argument(
        "-t", "--text", dest="text", type=str, required=True,
        help="This text will be used to render an image",
    )

    parser.add_argument(
        "-s", "--save", dest="save_path", metavar='FILE',
        help="Save the generated file to the specified path",
    )
    parser.add_argument(
        "-r", "--render", dest="render_path", metavar='FILE',
        help="Render an image to the specified path",
    )

    args = parser.parse_args(argv)  # In this example we won't use the args

    if not argv:
        parser.print_help()
        return

    if not args.text:
        print("Error: --text=\"some string\" argument not given, aborting.")
        parser.print_help()
        return

    # Run the example function
    example_function(args.text, args.save_path, args.render_path)

    print("batch job finished, exiting")


if __name__ == "__main__":
    main()
