import argparse
import importlib
import os

from flask import Flask, Response

from fbin.db import db, File

parser = argparse.ArgumentParser()
parser.add_argument('-s', '--source-config-file', default='fbin/fbin.cfg')
parser.add_argument('-t', '--target-config-file', required=True)
parser.add_argument('--update-db', action='store_true', help='Update DB as well')
parser.add_argument('-n', '--dry-run', action='store_true', help='Do not update anything')
args = parser.parse_args()


class DummyFile:
    def __init__(self, stream, filename, content_length):
        self.stream = stream
        self.filename = filename
        self.content_length = content_length

    def save(self, fp):
        chunk = self.stream.read(10 * 1024)
        while chunk:
            fp.write(chunk)
            chunk = self.stream.read(10 * 1024)


class IterStream:
    def __init__(self, it):
        self._it = it

    def read(self, n):
        try:
            return next(self._it)
        except StopIteration:
            return None


def main():
    source_storage = importlib.import_module(source_app.config.get('STORAGE_MODULE', '.file_storage.filesystem'),
            package='fbin').Storage(source_app)
    target_storage = importlib.import_module(target_app.config.get('STORAGE_MODULE', '.file_storage.filesystem'),
            package='fbin').Storage(target_app)
    copy_list = []
    with source_app.app_context():
        db.init_app(source_app)
        print('Finding existing files')
        for f in db.session.query(File).all():
            if f.user:
                db.session.refresh(f.user)
            if source_storage.file_exists(f) and not target_storage.file_exists(f):
                print('COPY: ', end='')
                copy_list.append(f)
            else:
                print('SKIP: ', end='')
            print(f.hash, f.filename)
    if not copy_list:
        print('No valid files found')
        return
    print('Copying {} files'.format(len(copy_list)))
    for f in copy_list:
        if args.dry_run:
            print('Would copy', f.hash, f.filename)
            continue
        print('Copying', f.hash, f.filename)
        with source_app.app_context():
            db.init_app(source_app)
            with source_app.test_request_context():
                source = source_storage.get_file(f)
        if isinstance(source, str) and os.path.exists(source):
            source = open(source, 'rb')
        elif isinstance(source, Response):
            source = IterStream(source.get_app_iter({'REQUEST_METHOD': 'GET'}))
        df = DummyFile(source, f.filename, f.size)
        with target_app.app_context():
            db.init_app(target_app)
            if args.update_db:
                if db.session.query(File).filter(File.hash == f.hash).one():
                    print('  Cannot copy this file; hash already exists in target DB')
                else:
                    target_storage.store_file(df, f.hash, f.user, f.ip)
            else:
                target_storage.upload_file(df, f.hash, f.user)


source_app = Flask('source')
target_app = Flask('target')
with source_app.app_context():
    source_app.config.from_pyfile(args.source_config_file)
with target_app.app_context():
    target_app.config.from_pyfile(args.target_config_file)
main()