#!/usr/bin/env python3

import argparse
import copy
import os
import re
import subprocess
import sys
import tempfile

import CommonMark_bkrs as CommonMark
import yaml

def format_keyword(line):
    words = line.split(' ')
    keyword = words[0]
    return '*{}* '.format(keyword) + line[len(keyword):]

def indent(line):
    prefix = ' ' * 4
    return '>{}{}'.format(prefix, line)

def format_match(keyword, line, m):
    n = len(m.groups())
    if n > 0:
        end = 0
        parts = []
        for i in range(1, n+1):
            parts.append(line[end:m.start(i)])
            thispart = line[m.start(i) : m.end(i)]
            parts.append('*{}*'.format(thispart))
            end = m.end(i)
        line = ''.join(parts) + line[m.end(n):]
    line = '{} {}'.format(keyword, line)
    return line

def format_backtick(c):
    if c == "`":
        return "`"
    return c

def format_chars(s):
    return ''.join(format_backtick(c) for c in s)

def format_scenario_step(bind, line, prev_keyword):
    debug('line: %r' % line)

    words = line.split()
    if not words:
        return line.strip(), prev_keyword

    keyword = words[0]
    real_keyword = keyword
    if keyword.lower() == 'and':
        if prev_keyword is None:
            sys.exit('AND may not be used on first step in snippet')
        real_keyword = prev_keyword
    debug('keyword: %r' % keyword)
    line = line[len(keyword):].lstrip()
    debug('line: %r' % line)

    for b in bind:
        debug('consider binding %r' % b)
        if real_keyword not in b:
            debug('keyword %r not in binding' % real_keyword)
            continue
        m = re.match(b[real_keyword.lower()], line, re.I | re.M)
        debug('m: %r' % m)
        if m and m.end() == len(line):
            debug('match: %r' % line)
            debug('     : %r' % m.groupdict())
            line = format_match(keyword, line, m)
            break
    else:
        line = '{} {}'.format(keyword, line)

    if not line.strip():
        return line

    line = format_chars(line)

    debug('pre-indent: %r' % line)
    lines = line.splitlines()
    if len(lines) > 1:
        line = '\n'.join([lines[0] + '  '] + [indent(x) + '  ' for x in lines[1:]])
    debug('post-indent: %r' % line)

    return format_keyword(line), real_keyword

def count_leading_whitespace(s):
    n = 0
    while s and s[0].isspace():
        n += 1
        s = s[1:]
    return n

def skip_indent(s, indent):
    while indent > 0 and s and s[0].isspace():
        s = s[1:]
        indent -= 1
    return s

def get_steps(lines):
    step = []
    indent = None
    for line in lines:
        if not line.strip():
            yield '\n'.join(step)
            step = []
            indent = None
        elif line[0].isspace():
            if indent is None:
                indent = count_leading_whitespace(line)
            line = skip_indent(line, indent)
            step.append(line)
        else:
            yield '\n'.join(step)
            step = [line]
            indent = None
    if step:
        yield '\n'.join(step)

def format_fable_snippet(bind, lines):
#    debug('snippet: %r' % lines)
    prev_keyword = None
    output = []
    for step in get_steps(lines):
        debug('step: %r' % step)
        ln, prev_keyword = format_scenario_step(bind, step, prev_keyword)
        output.append(ln)
    return output

def is_fable_snippet(o):
    prefix = "```fable\n"
    return o.t == 'FencedCode' and o.info == 'fable'

def is_heading(o):
    return o.t =='ATXHeader'

def write_document(bind, f, o):
    pass

def write_atxheader(bind, f, o):
    f.write('{} {}\n\n'.format('#' * o.level, ' '.join(o.strings)))

def write_setextheader(bind, f, o):
    chars = {
        1: '=',
        2: '-',
    }
    c = chars[o.level]
    f.write('{}\n{}\n\n'.format(' '.join(o.strings), c * 72))

def write_paragraph(bind, f, o):
    for s in o.strings:
        f.write('{}\n'.format(s))
    f.write('\n')

def write_fable_snippet(bind, f, o):
    for line in format_fable_snippet(bind, o.strings[1:]):
        f.write('> {}  \n'.format(line))
    f.write('\n')

def write_not_fable_snippet(bind, f, o):
    fence = o.fence_char * o.fence_length
    lang = o.strings[0]
    f.write('{}{}\n'.format(fence, lang))
    for line in o.strings[1:]:
        f.write('{}\n'.format(line))
    f.write('{}\n'.format(fence))
    f.write('\n')

def write_fencedcode(bind, f, o):
    if is_fable_snippet(o):
        write_fable_snippet(bind, f, o)
    else:
        write_not_fable_snippet(bind, f, o)

def write_indentedcode(bind, f, o):
    for s in o.strings:
        f.write('    {}\n'.format(s))
    f.write('\n')

def write_horizontalrule(bind, f, o):
    f.write('---\n')

def write_list(bind, f, o):
    pass

def write_listitem(bind, f, o):
    bullet = o.list_data['bullet_char']
    offset = o.list_data['marker_offset']
    padding = o.list_data['padding']
    prefix = '{}{} '.format(' ' * offset, bullet)
    cont = ' ' * padding
    for c in o.children:
        prepend = prefix
        for s in c.strings:
            f.write('{}{}\n'.format(prepend, s))
            prepend = cont
    if o.last_line_blank:
        f.write('\n')
    return True

def write_referencedef(bind, f, o):
    for s in o.strings:
        f.write('{}\n'.format(s))

writers = {
    'Document': write_document,
    'ATXHeader': write_atxheader,
    'SetextHeader': write_setextheader,
    'Paragraph': write_paragraph,
    'FencedCode': write_fencedcode,
    'IndentedCode': write_indentedcode,
    'HorizontalRule': write_horizontalrule,
    'List': write_list,
    'ListItem': write_listitem,
    'ReferenceDef': write_referencedef,
}

def write(bind, f, o):
    if o.t not in writers:
        debug('{} not known'.format(repr(o.t)))
        return
    writer = writers[o.t]
    return writer(bind, f, o)

def walk(o, func):
    done = func(o)
    if not done:
        for c in o.children:
            walk(c, func)

def infer_basename(markdowns):
    root, ext = os.path.splitext(markdowns[0])
    if ext not in ['.md', '.mdwn']:
        sys.exit('Input filenames must end in .md or .mdwn')
    return root

# This only allows one markdown filename. This is crap. But I can't
# get it work with -- otherwise. What I want is for the following to
# work:
#    ftt-docgetn --pdf foo.md bar.md -- --pandoc-arg --other-pandoc-arg
# but I can't make it work.
def parse_cli():
    p = argparse.ArgumentParser()
    p.add_argument('--pdf', action='store_true')
    p.add_argument('--html', action='store_true')
    p.add_argument('markdown', nargs=1)
    args, pandoc_args = p.parse_known_args()
    return args, pandoc_args

def debug(msg):
    if False:
        sys.stderr.write('DEBUG: {}\n'.format(msg))
        sys.stderr.flush()

def pandoc(args):
    argv = ['ftt-pandoc'] + args
    subprocess.check_call(argv)

args, pandoc_args = parse_cli()

text = ''.join(open(filename).read() for filename in args.markdown)

basename = infer_basename(args.markdown)
dirname = os.path.dirname(basename)

with open(basename + '.yaml') as f:
    bindings = yaml.safe_load(f)


start = '---\n'
end = '\n...\n'
if text.startswith(start):
    meta, text = text.split(end, 1)
    meta += end + '\n'
else:
    meta = ''

parser = CommonMark.DocParser()
ast = parser.parse(text)

if args.pdf or args.html:
    with tempfile.NamedTemporaryFile(mode='w', dir=dirname) as f:
        f.write(meta)
        walk(ast, lambda o: write(bindings, f, o))
        f.flush()
        if args.pdf:
            pandoc(['-o', basename + '.pdf', f.name] + pandoc_args)
        elif args.html:
            pandoc(['-o', basename + '.html', f.name] + pandoc_args)
else:
    sys.stdout.write(meta)
    walk(ast, lambda o: write(bindings, sys.stdout, o))