#!/usr/bin/env python3
# -*- python -*-

import sys
import subprocess
import re
import os
import sqlite3

from preserves import preserve, parse, stringify
from preserves.schema import load_schema_file, extend

cache = sqlite3.connect('.mdbook-ditaa.sqlite')
try:
    cache.cursor().execute('CREATE TABLE diagrams(source text, svg text)')
except:
    pass

try:
    schema = load_schema_file('./book.prb').book
except FileNotFoundError:
    subprocess.check_output(['sh', '-c', 'preserves-schemac --no-bundle .:book.prs > book.prb'])
    schema = load_schema_file('./book.prb').book

@extend(schema.Book)
def expand(self, context):
    for i in self.sections:
        i.expand(context)

@extend(schema.BookItem.chapter)
def expand(self, context):
    self.value.expand(context)

@extend(schema.BookItem._ALL)
def expand(self, context):
    pass

@extend(schema.Chapter)
def expand(self, context):
    if self.source_path.VARIANT.name == 'present':
        directory = os.path.dirname(self.source_path.value)
        self.content = expand_codeblock(DITAA_TAG, expand_ditaa, self.content, context, directory)
    for i in self.sub_items:
        i.expand(context)

def expand_codeblock(language_re, expander, s, *args):
    return re.sub('^```' + language_re + '\n(.*?)\n```\n', lambda m: expander(m, *args), s, 0, re.M | re.S)

figure_count = 0
def next_filename():
    global figure_count
    figure_count = figure_count + 1
    return f'figure_{figure_count}'

DITAA_TAG = r'ditaa(?: ((?:\w|-)+))?'
def expand_ditaa(m, context, directory):
    sourcedir = context['config']['book']['src']
    baseurl = context['config']['output']['html']['site-url']
    filename = os.path.join(directory, (m.group(1) or next_filename()) + '.svg')
    sys.stderr.write(f'ditaa {filename} ...')

    ditaa_source = m.group(2)

    cached = list(cache.cursor().execute('SELECT svg FROM diagrams WHERE source = ?', (ditaa_source,)))
    if cached:
        svg = cached[0][0]
    else:
        svg = subprocess.check_output(['ditaa', '--svg', '-'], input=ditaa_source.encode('utf-8'))
        svg = svg.decode('utf-8')
        cache.cursor().execute('INSERT INTO diagrams VALUES (?, ?)', (ditaa_source, svg))
        cache.cursor().execute('COMMIT')

    svgfilename = os.path.join(sourcedir, output_prefix, filename)
    os.makedirs(os.path.dirname(svgfilename), exist_ok=True)

    need_write = True
    if os.path.exists(svgfilename):
        with open(svgfilename, 'rt') as f:
            existing = f.read()
        if existing == svg:
            need_write = False
    if need_write:
        sys.stderr.write('updated\n')
        with open(svgfilename, 'wt') as f:
            f.write(svg)
    else:
        sys.stderr.write('unchanged\n')

    return f'<p><img class="ditaa" alt="{filename}" src="{os.path.join(baseurl, output_prefix, filename)}"></p>\n'

def structure(items):
    answer = []
    for i in items:
        if i.VARIANT.name == 'chapter':
            a = structure(i.value.sub_items)
            answer.append({ i.value.name: a })
    return answer

if __name__ == '__main__':
    if sys.argv[-2:-1] == ['supports']:
        sys.exit(0 if sys.argv[-1] == 'html' else 1)
    output_prefix = sys.argv[1] if len(sys.argv) > 1 else 'figures'

    raw = parse(sys.stdin.read())
    # sys.stderr.write(stringify(raw, indent=2) + '\n')
    i = schema.PreprocessorInput.decode(raw)
    # sys.stderr.write(stringify(preserve(i.context), indent=2) + '\n')
    i.book.expand(i.context)
    print(stringify(preserve(i.book), with_commas=True))