#!/usr/bin/env python

API_VERSION = 3

# Backend for the 'dtdesign' drawio plugin.
# Offers a repository to store/load drawio diagrams, and conversion to OML, and updating Fuseki with newly generated triples.

# python standard library:
import os
import io
import sys
import json
import tempfile
import xml.etree.ElementTree as ET
import subprocess
import argparse

# packages from pypi:
import flask
import flask_cors

# our own packages:
from drawio2py.parser import Parser as drawio_parser
from drawio2py.generator import generate_diagram
import drawio2py.util
from drawio2oml.convert import page_to_oml
from drawio2oml.bundle.oml_generator import write_bundle
from drawio2oml import util
from xopp2py import parser as xopp_parser
from xopp2oml import writer as xopp_oml_writer

from drawio2oml.pt import fetcher as pt_fetcher
from drawio2oml.pt import renderer as pt_renderer

argparser = argparse.ArgumentParser(
    description = "Backend for DTDesign drawio plugin.")
argparser.add_argument('projectdir', help="Path to SystemDesignOntology2Layers OML project directory (containing \"build.gradle\"). Example: /home/maestro/repos/dtdesign/examples/oml/SystemDesignOntology2Layers")
argparser.add_argument('shapelibdir', help="Path to where the Draw.io shape libraries (bunch of XML files) for FTG, PM and PT are at. Necessary for rendering process traces. Example: /home/maestro/repos/drawio/src/main/webapp/myPlugins/shape_libs")
args = argparser.parse_args() # exits on error

WEE = "http://localhost:8081"
WEE_FETCHER = pt_fetcher.Fetcher(WEE)

# See below
DTDESIGN_PROJECT_DIR = args.projectdir
SHAPE_LIB_DIR = args.shapelibdir

# Quick check to see if the projectdir argument is valid:
if not os.path.isfile(DTDESIGN_PROJECT_DIR + "/build.gradle"):
    sys.exit("Invalid projectdir: " + DTDESIGN_PROJECT_DIR)

# Quick check to see if the shapelibdir argument is valid:
if not os.path.isfile(SHAPE_LIB_DIR + "/pt.xml"):
    sys.exit("Invalid shapelibdir: " + SHAPE_LIB_DIR)

OML_DESCRIPTION_DIR = DTDESIGN_PROJECT_DIR + "/src/oml/ua.be/sdo2l/description"
OML_ARTIFACT_DIR = OML_DESCRIPTION_DIR + "/artifacts"
FILES_DIR = DTDESIGN_PROJECT_DIR + "/src/oml/ua.be/sdo2l/files"

DRAWIO_DIR = FILES_DIR + "/drawio"
XOPP_DIR = FILES_DIR + "/xopp"
CSV_DIR = FILES_DIR + "/csv"
ANYFILE_DIR = FILES_DIR + "/file"


print()
print(" ",DTDESIGN_PROJECT_DIR)
print("    │")
print("    ├ description/")
print("    │   │")
print("    │   ├ bundle.oml")
print("    │   │   ↳ re-generated before every oml build")
print("    │   │")
print("    │   └ artifacts/")
print("    │       ↳ generated OML artifacts will be put here")
print("    │")
print("    └ files/")
print("        │")
print("        ├ drawio/")
print("        │   ↳ Drawio diagrams (XML) will be put here")
print("        │")
print("        ├ xopp/")
print("        │   ↳ Xournal++ (Gzipped XML) will be put here")
print("        │")
print("        └ csv/")
print("            ↳ CSV files will be put here")
print()

# Create directories if they don't exist yet:
for d in [DRAWIO_DIR, XOPP_DIR, CSV_DIR, ANYFILE_DIR]:
    os.makedirs(d, exist_ok=True)

app = flask.Flask(__name__)
flask_cors.CORS(app)

# API version
@app.route("/version", methods=["GET"])
def version():
    return json.dumps(API_VERSION), 200

@app.route("/files/<path:filepath>", methods=["GET"])
def files_ls(filepath):
    if "/../" in filepath or filepath[:3] == "../" or filepath[-3:] == "/..":
        # Security measure, not allowed to break out of /files/ directory:
        return "Illegal path, '..' directory traveral not allowed", 403
    if os.path.isdir(FILES_DIR + '/' + filepath):
        # Send JSON array of filenames of files in directory:
        return flask.Response(json.dumps(os.listdir(FILES_DIR + '/' + filepath)))
    else:
        # Send file contents:
        return flask.send_file(FILES_DIR + '/' + filepath, as_attachment=True)

@app.route("/files/drawio/<model_name>", methods=["PUT"])
def put_drawio_file(model_name):
    diagram = flask.request.data # the serialized XML of a drawio page.
    # Parse XML/drawio and call the right drawio->DSL parser (e.g., FTG, PM, ...):
    tree = ET.fromstring(diagram)
    page = drawio_parser.parse_page(tree)
    try:
        parsed_as = page_to_oml(page=page, outdir=OML_ARTIFACT_DIR, input_uri=flask.request.url)
    except Exception as e:
        return str(e), 500
    # If the above was successful, store the serialized XML:
    with open(DRAWIO_DIR+'/'+model_name, 'wb') as f:
        f.write(diagram)
    return json.dumps(parsed_as), 200 # OK

# Even though the slashes in pt_iri will be escaped, we still have to tell Flask it's a 'path' or it won't accept it.
@app.route("/render_pt/<path:pt_iri>", methods=["GET"])
def render_pt(pt_iri):
    last_event = WEE_FETCHER.get_pt(pt_iri)
    id_gen = drawio2py.util.DrawioIDGenerator()
    page = drawio2py.util.generate_empty_page(id_gen, "XXX")
    default_layer = page.root.children[0]
    pt_renderer.render(SHAPE_LIB_DIR, last_event, parent=default_layer, id_gen=id_gen)
    diagram_node = generate_diagram(page)
    return ET.tostring(diagram_node, encoding="unicode"), 200 # OK

@app.route("/files/xopp/<file_name>", methods=["PUT"])
def put_xopp_file(file_name):
    if file_name[-5:] != ".xopp":
        return "File extension must be .xopp", 500
    model_name = file_name[:-5]
    xopp_data = flask.request.data # the file contents (gzipped XML)
    # Convert to OML and store the OML:
    try:
        xopp_as = xopp_parser.parseFile(io.BytesIO(initial_bytes=xopp_data))
        with open(OML_ARTIFACT_DIR+'/'+model_name+"_xopp.oml", 'wt') as f:
            xopp_oml_writer.writeOML(xopp_as,
                inputfile=flask.request.url,
                model_name=model_name,
                namespaces=util.DTDESIGN_NAMESPACES, # use the namespaces from this repo
                ostream=f)
    except Exception as e:
        return str(e), 500
    # If the above was successful, store the raw XOPP file:
    with open(XOPP_DIR+'/'+model_name, 'wb') as f:
        f.write(xopp_data)
    return json.dumps(["xopp"]), 200 # OK

@app.route("/files/csv/<model_name>", methods=["PUT"])
def put_csv_file(model_name):
    csv_data = flask.request.data # the file contents (gzipped XML)
    # We don't convert CSV to OML...
    # (TODO) But we probably store *something* about the CSV in OML?
    # Store the raw XOPP file:
    with open(CSV_DIR+'/'+model_name, 'wb') as f:
        f.write(csv_data)
    return json.dumps(["csv"]), 200 # OK

@app.route("/files/file/<model_name>", methods=["PUT"])
def put_any_file(model_name):
    file_data = flask.request.data # the file contents (gzipped XML)
    # (TODO) We probably should store *something* about the file in OML?
    # Store the raw file:
    with open(ANYFILE_DIR+'/'+model_name, 'wb') as f:
        f.write(file_data)
    return json.dumps(["file"]), 200 # OK

# TODO: this endpoint should queue rebuilds (using Futures?), such that only one rebuild is running at a time.
@app.route("/rebuild_oml", methods=["PUT"])
def rebuild_oml():
    with open(OML_DESCRIPTION_DIR+'/bundle.oml', 'wt') as f:
        write_bundle(OML_DESCRIPTION_DIR, f)
    # owlLoad builds OML and makes Fuseki load the new triples
    owlLoad = subprocess.run(["gradle", "owlLoad"], cwd=DTDESIGN_PROJECT_DIR,
        stdout=subprocess.PIPE, stderr=subprocess.STDOUT, # combine both streams into one
        text=True,
        )
    if owlLoad.returncode != 0:
        return owlLoad.stdout, 500 # Return all output of the failed owlLoad
    else:
        return owlLoad.stdout, 200 # OK

app.run(host="0.0.0.0")