#!/usr/bin/env python3
import contextlib
import csv
import os
import sqlite3
import warnings
from operator import attrgetter
from typing import List

import click
from loguru import logger
from lxml import etree as ET
from tqdm import tqdm

from .lib import (
    TagGroup,
    convert_db_to_parquet,
    flatten,
    insert_into_db,
    ns,
    sorted_groupby,
)


def alto_to_dict(alto, raise_errors=True):
    """Convert ALTO metadata to a nested dictionary"""

    value = {}

    # Iterate through each group of tags
    for tag, group in sorted_groupby(alto, key=attrgetter("tag")):
        group = list(group)

        localname = ET.QName(tag).localname
        alto_namespace = ET.QName(tag).namespace
        namespaces = {"alto": alto_namespace}

        if localname == "Description":
            value[localname] = (
                TagGroup(tag, group)
                .is_singleton()
                .has_no_attributes()
                .descend(raise_errors)
            )
        elif localname == "MeasurementUnit":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )
        elif localname == "OCRProcessing":
            value[localname] = TagGroup(tag, group).is_singleton().descend(raise_errors)
        elif localname == "Processing":
            # TODO This enumerated descent is used more than once, DRY!
            for n, e in enumerate(group):
                value[f"{localname}{n}"] = alto_to_dict(e, raise_errors)
        elif localname == "ocrProcessingStep":
            for n, e in enumerate(group):
                value[f"{localname}{n}"] = alto_to_dict(e, raise_errors)
        elif localname == "preProcessingStep":
            for n, e in enumerate(group):
                value[f"{localname}{n}"] = alto_to_dict(e, raise_errors)
        elif localname == "processingDateTime":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )
        elif localname == "processingSoftware":
            value[localname] = TagGroup(tag, group).is_singleton().descend(raise_errors)
        elif localname == "processingAgency":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )
        elif localname == "processingStepDescription":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )
        elif localname == "processingStepSettings":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )
        elif localname == "softwareCreator":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )
        elif localname == "softwareName":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )
        elif localname == "softwareVersion":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )

        elif localname == "sourceImageInformation":
            value[localname] = (
                TagGroup(tag, group)
                .is_singleton()
                .has_no_attributes()
                .descend(raise_errors)
            )
        elif localname == "fileName":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )
        elif localname == "fileIdentifier":
            value[localname] = (
                TagGroup(tag, group).is_singleton().has_no_attributes().text()
            )

        elif localname == "Layout":
            value[localname] = (
                TagGroup(tag, group)
                .is_singleton()
                .has_no_attributes()
                .descend(raise_errors)
            )
        elif localname == "Page":
            value[localname] = {}
            value[localname].update(TagGroup(tag, group).is_singleton().attributes())
            for attr in ("WIDTH", "HEIGHT"):
                if attr in value[localname]:
                    try:
                        value[localname][attr] = int(value[localname][attr])
                    except ValueError:
                        del value[localname][attr]
            value[localname].update(TagGroup(tag, group).subelement_counts())
            value[localname].update(
                TagGroup(tag, group).xpath_statistics("//alto:String/@WC", namespaces)
            )

            # Count all alto:String elements with TAGREFS attribute
            value[localname].update(
                TagGroup(tag, group).xpath_count("//alto:String[@TAGREFS]", namespaces)
            )

        elif localname == "Styles":
            pass
        elif localname == "Tags":
            value[localname] = {}
            value[localname].update(TagGroup(tag, group).subelement_counts())
        else:
            if raise_errors:
                print(value)
                raise ValueError('Unknown tag "{}"'.format(tag))
            else:
                pass

    return value


def walk(m):
    # XXX do this in mods4pandas, too
    if os.path.isdir(m):
        logger.info(f"Scanning directory {m}")
        for f in os.scandir(m):
            if f.is_file() and not f.name.startswith("."):
                yield f.path
            elif f.is_dir():
                try:
                    yield from walk(f.path)
                except PermissionError:
                    warnings.warn(f"Error walking {f.path}")
    else:
        yield m.path


@click.command()
@click.argument("alto_files", type=click.Path(exists=True), required=True, nargs=-1)
@click.option(
    "--output",
    "-o",
    "output_file",
    type=click.Path(),
    help="Output Parquet file",
    default="alto_info_df.parquet",
    show_default=True,
)
def process_command(alto_files: List[str], output_file: str):
    """
    A tool to convert the ALTO metadata in INPUT to a pandas DataFrame.

    INPUT is assumed to be a ALTO document. INPUT may optionally be a directory. The tool then reads
    all files in the directory.

    alto4pandas writes multiple output files:
    - A Parquet DataFrame
    - A SQLite database
    - and a CSV file with all conversion warnings.
    """

    process(alto_files, output_file)


def process(alto_files: List[str], output_file: str):
    # Extend file list if directories are given
    alto_files_real = []
    for m in alto_files:
        for x in walk(m):
            alto_files_real.append(x)

    # Prepare output files
    with contextlib.suppress(FileNotFoundError):
        os.remove(output_file)
    output_file_sqlite3 = output_file + ".sqlite3"
    with contextlib.suppress(FileNotFoundError):
        os.remove(output_file_sqlite3)

    logger.info("Writing SQLite DB to {}".format(output_file_sqlite3))
    con = sqlite3.connect(output_file_sqlite3)

    # Process ALTO files
    with open(output_file + ".warnings.csv", "w") as csvfile:
        csvwriter = csv.writer(csvfile)
        logger.info("Processing ALTO files")
        for alto_file in tqdm(alto_files_real, leave=False):
            try:
                root = ET.parse(alto_file).getroot()
                alto = root  # XXX .find('alto:alto', ns) does not work here

                with warnings.catch_warnings(record=True) as caught_warnings:
                    warnings.simplefilter("always")  # do NOT filter double occurrences

                    # ALTO
                    d = flatten(alto_to_dict(alto, raise_errors=True))
                    # "meta"
                    d["alto_file"] = alto_file
                    d["alto_xmlns"] = ET.QName(alto).namespace

                    # Save
                    insert_into_db(con, "alto_info", d)
                    con.commit()

                    if caught_warnings:
                        # PyCharm thinks caught_warnings is not Iterable:
                        # noinspection PyTypeChecker
                        for caught_warning in caught_warnings:
                            csvwriter.writerow([alto_file, caught_warning.message])
            except Exception as e:
                logger.error("Exception in {}: {}".format(alto_file, e))
                import traceback

                traceback.print_exc()

    # Convert the alto_info SQL to a pandas DataFrame
    logger.info("Writing DataFrame to {}".format(output_file))
    convert_db_to_parquet(con, "alto_info", "alto_file", output_file)


def main():
    for prefix, uri in ns.items():
        ET.register_namespace(prefix, uri)

    process_command()


if __name__ == "__main__":
    main()