#!/usr/bin/python3

import sys, re, os
import sqlite3
import urllib.parse, requests
import time, signal

import argparse
parser = argparse.ArgumentParser(description="""
Downloads images from URLs in an image database, into an output directory,
with names of the form 'pageId1.ext1'.

SIGINT causes the program to finish an ongoing download and exit.
The program can be re-run to continue downloading, and looks
in the output directory do decide what to skip.
""", formatter_class=argparse.RawDescriptionHelpFormatter)
parser.parse_args()

imgDb = 'imgData.db' # About 130k image names
outDir = 'imgs'
licenseRegex = re.compile(r'cc0|cc([ -]by)?([ -]sa)?([ -][1234]\.[05])?( \w\w\w?)?', flags=re.IGNORECASE)
# In testing, this downloaded about 100k images, over several days

if not os.path.exists(outDir):
	os.mkdir(outDir)
print('Checking for already-downloaded images')
fileList = os.listdir(outDir)
pageIdsDone: set[int] = set()
for filename in fileList:
	basename, extension = os.path.splitext(filename)
	pageIdsDone.add(int(basename))
print(f'Found {len(pageIdsDone)}')

# Set SIGINT handler
interrupted = False
oldHandler = None
def onSigint(sig, frame):
	global interrupted
	interrupted = True
	signal.signal(signal.SIGINT, oldHandler)
oldHandler = signal.signal(signal.SIGINT, onSigint)

print('Opening database')
dbCon = sqlite3.connect(imgDb)
dbCur = dbCon.cursor()
print('Starting downloads')
iterNum = 0
query = 'SELECT page_id, license, artist, credit, restrictions, url FROM' \
	' imgs INNER JOIN page_imgs ON imgs.name = page_imgs.img_name'
for pageId, license, artist, credit, restrictions, url in dbCur.execute(query):
	if pageId in pageIdsDone:
		continue
	if interrupted:
		print('Exiting loop')
		break
	# Check for problematic attributes
	if license is None or licenseRegex.fullmatch(license) is None:
		continue
	if artist is None or artist == '' or len(artist) > 100 or re.match(r'(\d\. )?File:', artist) is not None:
		continue
	if credit is None or len(credit) > 300 or re.match(r'File:', credit) is not None:
		continue
	if restrictions is not None and restrictions != '':
		continue
	# Download image
	iterNum += 1
	print(f'Iteration {iterNum}: Downloading for page-id {pageId}')
	urlParts = urllib.parse.urlparse(url)
	extension = os.path.splitext(urlParts.path)[1]
	if len(extension) <= 1:
		print(f'WARNING: No filename extension found in URL {url}')
		sys.exit(1)
	outFile = f'{outDir}/{pageId}{extension}'
	headers = {
		'user-agent': 'terryt.dev (terry06890@gmail.com)',
		'accept-encoding': 'gzip',
	}
	try:
		response = requests.get(url, headers=headers)
		with open(outFile, 'wb') as file:
			file.write(response.content)
		time.sleep(1)
			# https://en.wikipedia.org/wiki/Wikipedia:Database_download says to 'throttle self to 1 cache miss per sec'
			# It's unclear how to properly check for cache misses, so this just aims for 1 per sec
	except Exception as e:
		print(f'Error while downloading to {outFile}: {e}')
print('Closing database')
dbCon.close()