"""CLI: bring an existing HTML article in as a guide.

    flask guides import-html PATH [PATH ...]

A site that adopts this app usually arrives with a folder of procedures already
written - styled HTML pages that get mailed around and opened off a share. This
imports them so they live where they are used, become searchable, tickable and
printable, and stop being a file somebody has to find.

Imports land as DRAFTS, always. The conversion is faithful but it is not a
render: layout, colour and anything decorative are dropped on purpose, and a
person should read the result before anybody is told to follow it.
"""

import click
from flask.cli import AppGroup, with_appcontext

from shopdb.api import db

from .models import Guide, GuideImage
from .services import authoring
from .services.blocks import BlockError
from .services.htmlimport import parse


# Mirrors what the upload route accepts. An import must not be able to store an
# image the editor would have refused, or the guide renders here and nowhere
# else.
ALLOWEDIMAGETYPES = ('image/png', 'image/jpeg', 'image/gif', 'image/webp')
MAXIMAGEBYTES = 8 * 1024 * 1024


def _slugify(title):
    """Same rule as the API's, kept here so the CLI does not import a route."""
    import re
    base = re.sub(r'[^a-z0-9]+', '-', (title or '').lower()).strip('-') or 'guide'
    base = base[:180]
    candidate = base
    suffix = 2
    while Guide.query.filter(Guide.slug == candidate).first() is not None:
        candidate = '{}-{}'.format(base, suffix)
        suffix += 1
    return candidate


def build_cli():
    guides_cli = AppGroup('guides')

    @guides_cli.command('import-html')
    @click.argument('paths', nargs=-1, required=True,
                    type=click.Path(exists=True, dir_okay=False))
    @click.option('--title', default=None,
                  help='Override the title taken from the article.')
    @click.option('--tags', default=None,
                  help='Comma-separated tags for every guide imported.')
    @click.option('--userid', type=int, default=None,
                  help='Record this user as the author.')
    @click.option('--replace', is_flag=True,
                  help='If a guide already has this slug, edit it in place '
                       '(a new revision) instead of creating a second one.')
    @click.option('--apply/--dry-run', default=False,
                  help='Write to the database. The default reports only.')
    @with_appcontext
    def import_html(paths, title, tags, userid, replace, apply):
        """Convert HTML article(s) into draft guides."""
        if title and len(paths) > 1:
            raise click.UsageError('--title names one guide; pass one file.')

        for path in paths:
            with open(path, encoding='utf-8', errors='replace') as handle:
                parsed = parse(handle.read())

            name = title or parsed['title']
            counts = {}
            for block in parsed['blocks']:
                counts[block['type']] = counts.get(block['type'], 0) + 1

            click.echo('{}'.format(path))
            click.echo('  title   {}'.format(name))
            click.echo('  blocks  {} ({})'.format(
                len(parsed['blocks']),
                ', '.join('{} {}'.format(v, k) for k, v in sorted(counts.items()))))
            click.echo('  images  {}'.format(len(parsed['images'])))
            for note in parsed['skipped']:
                click.echo('  skipped {}'.format(note))

            rejected = [image for image in parsed['images']
                        if image['mimetype'] not in ALLOWEDIMAGETYPES
                        or len(image['data']) > MAXIMAGEBYTES]
            for image in rejected:
                click.echo('  DROPPED {} ({}, {:.1f} MB) - not an accepted image'
                           .format(image['token'], image['mimetype'],
                                   len(image['data']) / 1048576))

            if not apply:
                click.echo('  dry run, nothing written. Pass --apply to import.')
                continue

            try:
                guide = _import(parsed, name, tags, userid, replace, rejected)
            except BlockError as error:
                db.session.rollback()
                click.echo('  FAILED  {}'.format(error))
                continue

            db.session.commit()
            click.echo('  imported as /guides/{} (draft, revision {})'
                       .format(guide.slug, guide.revision))

    return [guides_cli]


def _import(parsed, name, tags, userid, replace, rejected):
    """Create or update the guide and its images. Caller commits."""
    slug = None
    guide = None
    if replace:
        # Match on the slug the title WOULD produce, which is how somebody
        # re-imports a corrected article over the one they imported yesterday.
        import re
        wanted = re.sub(r'[^a-z0-9]+', '-', (name or '').lower()).strip('-')
        guide = Guide.query.filter(Guide.slug == wanted).first()

    if guide is None:
        slug = _slugify(name)
        guide = Guide(title=name, slug=slug, status='draft', createdby=userid)
        db.session.add(guide)
        db.session.flush()

    # Images first: the block needs the stored id, and an id only exists once
    # the row does.
    droppedtokens = {image['token'] for image in rejected}
    ids = {}
    for image in parsed['images']:
        if image['token'] in droppedtokens:
            continue
        row = GuideImage(guideid=guide.guideid, filename=image['filename'],
                         mimetype=image['mimetype'],
                         bytesize=len(image['data']), data=image['data'],
                         uploadedby=userid)
        db.session.add(row)
        db.session.flush()
        ids[image['token']] = row.guideimageid

    blocks = []
    for block in parsed['blocks']:
        block = dict(block)
        token = block.pop('imagetoken', None)
        if token is not None:
            if token not in ids:
                continue      # its image was dropped; the caption would lie
            block['imageid'] = ids[token]
        blocks.append(block)

    authoring.save(guide, title=name, summary=parsed['summary'] or None,
                   tags=tags, blocks=blocks,
                   note='Imported from HTML', userid=userid)
    return guide