#!/usr/bin/python3

"""
Looks up a page with title title1 in the wiki dump, using the dump-index
db, and prints the corresponding <page>.
"""

import sys
import bz2
import sqlite3

DUMP_FILE = 'enwiki-20220501-pages-articles-multistream.xml.bz2'
INDEX_DB = 'dumpIndex.db'

def lookupPage(dumpFile: str, indexDb: str, pageTitle: str) -> None:
	print('Looking up offset in index db')
	dbCon = sqlite3.connect(indexDb)
	dbCur = dbCon.cursor()
	query = 'SELECT title, offset, next_offset FROM offsets WHERE title = ?'
	row = dbCur.execute(query, (pageTitle,)).fetchone()
	if row is None:
		print('Title not found')
		sys.exit(0)
	_, pageOffset, endOffset = row
	dbCon.close()
	print(f'Found chunk at offset {pageOffset}')
	#
	print('Reading from wiki dump')
	content: list[str] = []
	with open(dumpFile, mode='rb') as file:
		# Get uncompressed chunk
		file.seek(pageOffset)
		compressedData = file.read(None if endOffset == -1 else endOffset - pageOffset)
		data = bz2.BZ2Decompressor().decompress(compressedData).decode()
		# Look in chunk for page
		lines = data.splitlines()
		lineIdx = 0
		found = False
		pageNum = 0
		while not found:
			line = lines[lineIdx]
			if line.lstrip() == '<page>':
				pageNum += 1
				if pageNum > 100:
					print('ERROR: Did not find title after 100 pages')
					break
				lineIdx += 1
				titleLine = lines[lineIdx]
				if titleLine.lstrip() == '<title>' + pageTitle + '</title>':
					found = True
					print(f'Found title in chunk as page {pageNum}')
					content.append(line)
					content.append(titleLine)
					while True:
						lineIdx += 1
						line = lines[lineIdx]
						content.append(line)
						if line.lstrip() == '</page>':
							break
			lineIdx += 1
	#
	print('Content: ')
	print('\n'.join(content))

if __name__ == '__main__':
	import argparse
	parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
	parser.add_argument('title', help='The title to look up')
	args = parser.parse_args()
	#
	lookupPage(DUMP_FILE, INDEX_DB, args.title.replace('_', ' '))