#!/usr/bin/python3

import sys, os, re
import bz2
import sqlite3

import argparse
parser = argparse.ArgumentParser(description="""
Adds data from the wiki dump index-file into a database
""", formatter_class=argparse.RawDescriptionHelpFormatter)
parser.parse_args()

indexFile = 'enwiki-20220501-pages-articles-multistream-index.txt.bz2' # Had about 22e6 lines
indexDb = 'dumpIndex.db'

if os.path.exists(indexDb):
	raise Exception(f'ERROR: Existing {indexDb}')
print('Creating database')
dbCon = sqlite3.connect(indexDb)
dbCur = dbCon.cursor()
dbCur.execute('CREATE TABLE offsets (title TEXT PRIMARY KEY, id INT UNIQUE, offset INT, next_offset INT)')

print('Iterating through index file')
lineRegex = re.compile(r'([^:]+):([^:]+):(.*)')
lastOffset = 0
lineNum = 0
entriesToAdd: list[tuple[str, str]] = []
with bz2.open(indexFile, mode='rt') as file:
	for line in file:
		lineNum += 1
		if lineNum % 1e5 == 0:
			print(f'At line {lineNum}')
		#
		match = lineRegex.fullmatch(line.rstrip())
		assert match is not None
		offsetStr, pageId, title = match.group(1,2,3)
		offset = int(offsetStr)
		if offset > lastOffset:
			for t, p in entriesToAdd:
				try:
					dbCur.execute('INSERT INTO offsets VALUES (?, ?, ?, ?)', (t, int(p), lastOffset, offset))
				except sqlite3.IntegrityError as e:
					# Accounts for certain entries in the file that have the same title
					print(f'Failed on title "{t}": {e}', file=sys.stderr)
			entriesToAdd = []
			lastOffset = offset
		entriesToAdd.append((title, pageId))
for title, pageId in entriesToAdd:
	try:
		dbCur.execute('INSERT INTO offsets VALUES (?, ?, ?, ?)', (title, int(pageId), lastOffset, -1))
	except sqlite3.IntegrityError as e:
		print(f'Failed on title "{t}": {e}', file=sys.stderr)

print('Closing database')
dbCon.commit()
dbCon.close()