#!/usr/bin/python3

"""
Usage: pgdump-sort [options] <dump> [<sorted-dump>]
       pgdump-sort -h | --help | --version

Options:
  -n          Sort entries in natural order (requires python3 module natsort)

  -h --help   Show this usage and exit
  --version   Show version and exit
"""

from docopt import docopt
import os
import sys
import re
import tempfile
import shutil
from enum import Enum

_has_natsort = False
try:
	import natsort
	_has_natsort = True
except ModuleNotFoundError:
	pass

version='0.2'


RE_OBJDESC = re.compile(
	'-- (?P<isdata>(Data for )?)Name: (?P<name>.*?); '
	'Type: (?P<type>.*?); '
	'Schema: (?P<schema>.*?); '
	'Owner: (?P<owner>.*)'
)
RE_SEQSET = re.compile("SELECT pg_catalog.setval\('(?P<name>.*?)'.*")


class state(Enum):
	EMPTY = 1
	SETTINGS = 2
	DEF = 3
	DATA = 4
	COPY = 5
	INSERT = 6
	SEQSET = 7


class buffer(list):
	destdir = None
	st = state.EMPTY
	fname = None
	title = None

	def __init__(self, destdir, fsorted, fsorted_args):
		self.destdir = destdir
		self.fsorted = fsorted
		self.fsorted_args = fsorted_args

	def flushto(self, st, fname, title):
		#print("EVICTING", self.st, "to", self.fname, "New state:", st)

		# Trim ellipsing comments and empty lines
		while self and ('' == self[0] or self[0].startswith('--')):
			del self[0]
		while self and ('' == self[-1] or self[-1].startswith('--')):
			del self[-1]

		if len(self):
			if self.st in (state.COPY, state.INSERT):
				self[:] = sort_datalines(self, self.fsorted, self.fsorted_args)

			self[:] = [
				'--',
				self.title,
				'--',
				'',
			] + self

			with open(os.path.join(self.destdir, self.fname), "w") as out:
				out.writelines([l + '\n' for l in self])

		self.clear()
		self.st = st
		self.fname = fname
		self.title = title


	def proc_comment(self, line):
		# Returns True if the line is a comment, i.e. it has been processed
		if not line.startswith('--'):
			return False

		m = re.match(RE_OBJDESC, line)
		if not m:
			return True

		if 'SEQUENCE SET' == m.group('type'):
			st = state.SEQSET
		elif m.group('isdata'):
			st = state.DATA
		else:
			st = state.DEF

		fname = '%d-%s-%s-%s-%s' % (
			st.value,
			m.group('type'),
			m.group('schema'),
			m.group('name'),
			m.group('owner')
		)

		if 255 < len(fname):
			fname = fname[:255-3] + "..."

		self.flushto(st, fname, line)

		return True


def sort_datalines(lines, fsorted, fsorted_args):
	pre = []
	data = []
	post = []

	state = 0
	ptr = pre
	isins = False
	for line in lines:
		if 0 == state:
			if line.startswith('COPY'):
				ptr.append(line)
				ptr = data
				state = 1
			elif line.startswith('INSERT'):
				ptr = data
				ptr.append(line)
				isins = True
				state = 1
			else:
				ptr.append(line)
		elif 1 == state:
			if isins and '\n' == line or not isins and '\\.\n' == line:
				ptr = post
				ptr.append(line)
				status = 2
			else:
				ptr.append(line)
		else:
			ptr.append(line)

	return pre + fsorted(data, **fsorted_args) + post


def dissect(dump, destdir, fsorted, fsorted_args):
	buf = buffer(destdir, fsorted, fsorted_args)

	for line in open(dump):
		# trim trailing newline (if any)
		if '\n' == line[-1]:
			line = line[:-1]

		#print(buf.st.name.ljust(10), "\t[%s]" % line)
		if buf.st == state.EMPTY:
			if buf.proc_comment(line):
				pass
			elif '' == line:
				pass
			else:
				buf.flushto(state.SETTINGS, "%d-%s" % (state.SETTINGS.value, "SETTINGS"),
					'-- Sorted PostgreSQL database dump')
				buf.append(line)

		elif buf.st in (state.SETTINGS, state.DEF, state.INSERT):
			if buf.proc_comment(line):
				pass
			else:
				buf.append(line)

		elif buf.st == state.DATA:
			if line.startswith('COPY '):
				buf.st = state.COPY
			elif line.startswith('INSERT '):
				buf.st = state.INSERT
			buf.append(line)

		elif buf.st == state.COPY:
			buf.append(line)
			if r'\.' == line:
				buf.flushto(state.EMPTY, None, None)

		elif buf.st == state.SEQSET:
			if buf.proc_comment(line):
				pass
			elif line.startswith('SELECT pg_catalog.setval'):
				m = re.match(RE_SEQSET, line)
				line = "SELECT pg_catalog.setval('%s', 1, false);" % m.group('name')
				buf.append(line)
			else:
				buf.append(line)

		else:
			print("This should not happen")

	buf.flushto(state.EMPTY, None, None)


def recombine(destdir, dump, fsorted, fsorted_args):
	out = open(dump, 'w')

	first = True
	sorted_files = fsorted(os.listdir(destdir), **fsorted_args)
	for fname in sorted_files:
		if first:
			first = False
		else:
			out.write('\n')
		with open(os.path.join(destdir, fname)) as f:
			out.writelines(f.readlines())

	if sorted_files:
		out.writelines([
			'\n',
			'--\n',
			'-- Sorted dump complete\n',
			'--\n',
		])

	out.close()


def pgdump_sort(dump, sdump, fsorted=sorted, **fsorted_args):
	destdir = tempfile.mkdtemp(suffix=os.path.basename(dump), prefix='pgdump-sort')

	try:
		dissect(dump, destdir, fsorted, fsorted_args)
		recombine(destdir, sdump, fsorted, fsorted_args)

	finally:
		shutil.rmtree(destdir)

natsort_error = \
"""In order to use natural sort you need to install natsort module:
   pip install natsort
"""

if __name__ == '__main__':
	args = docopt(__doc__, version=version)

	dump = args['<dump>']
	sdump = args['<sorted-dump>']
	if sdump is None:
		sdump = re.sub(r'\.sql$', '', dump) + '-sorted.sql'

	if args['-n']:
		if _has_natsort:
			fsorted = natsort.natsorted
			fsorted_args = {'alg': natsort.ns.IGNORECASE}
		else:
			print(natsort_error, file=sys.stderr)
			exit(1)
	else:
		fsorted = sorted
		fsorted_args = {}


	pgdump_sort(dump, sdump, fsorted, **fsorted_args)