# Copyright: Ankitects Pty Ltd and contributors
# License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html

"""
This file contains the Python portion of the template rendering code.

Templates can have filters applied to field replacements. The Rust template
rendering code will apply any built in filters, and stop at the first
unrecognized filter. The remaining filters are returned to Python,
and applied using the hook system. For example,
{{myfilter:hint:text:Field}} will apply the built in text and hint filters,
and then attempt to apply myfilter. If no add-ons have provided the filter,
the filter is skipped.

Add-ons can register a filter with the following code:

from anki import hooks
hooks.field_replacement_filter.append(myfunc)

This will call myfunc, passing the field text in as the first argument.
Your function should decide if it wants to modify the text by checking
the filter_name argument, and then return the text whether it has been
modified or not.

A Python implementation of the standard filters is currently available in the
template_legacy.py file, using the legacy addHook() system.
"""

from __future__ import annotations

import re
from typing import Dict, List, Optional, Tuple

import anki
from anki import hooks
from anki.hooks import runFilter
from anki.rsbackend import TemplateReplacementList


def render_card(
    col: anki.storage._Collection,
    qfmt: str,
    afmt: str,
    fields: Dict[str, str],
    card_ord: int,
) -> Tuple[str, str]:
    "Renders the provided templates, returning rendered q & a text."
    (qnodes, anodes) = col.backend.render_card(qfmt, afmt, fields, card_ord)

    qtext = apply_custom_filters(qnodes, fields, front_side=None)
    atext = apply_custom_filters(anodes, fields, front_side=qtext)

    return qtext, atext


def apply_custom_filters(
    rendered: TemplateReplacementList, fields: Dict[str, str], front_side: Optional[str]
) -> str:
    "Complete rendering by applying any pending custom filters."
    # template already fully rendered?
    if len(rendered) == 1 and isinstance(rendered[0], str):
        return rendered[0]

    res = ""
    for node in rendered:
        if isinstance(node, str):
            res += node
        else:
            # do we need to inject in FrontSide?
            if node.field_name == "FrontSide" and front_side is not None:
                node.current_text = front_side

            field_text = node.current_text
            for filter_name in node.filters:
                field_text = hooks.run_field_replacement_filter(
                    field_text, node.field_name, filter_name, fields
                )
                # legacy hook - the second and fifth argument are no longer used
                field_text = runFilter(
                    "fmod_" + filter_name, field_text, "", fields, node.field_name, ""
                )

            res += field_text
    return res


# Cloze handling
##########################################################################

# Matches a {{c123::clozed-out text::hint}} Cloze deletion, case-insensitively.
# The regex should be interpolated with a regex number and creates the following
# named groups:
#   - tag: The lowercase or uppercase 'c' letter opening the Cloze.
#          The c/C difference is only relevant to the legacy code.
#   - content: Clozed-out content.
#   - hint: Cloze hint, if provided.
clozeReg = r"(?si)\{\{(?P<tag>c)%s::(?P<content>.*?)(::(?P<hint>.*?))?\}\}"

# Constants referring to group names within clozeReg.
CLOZE_REGEX_MATCH_GROUP_TAG = "tag"
CLOZE_REGEX_MATCH_GROUP_CONTENT = "content"
CLOZE_REGEX_MATCH_GROUP_HINT = "hint"

# used by the media check functionality
def expand_clozes(string: str) -> List[str]:
    "Render all clozes in string."
    ords = set(re.findall(r"{{c(\d+)::.+?}}", string))
    strings = []

    def qrepl(m):
        if m.group(CLOZE_REGEX_MATCH_GROUP_HINT):
            return "[%s]" % m.group(CLOZE_REGEX_MATCH_GROUP_HINT)
        else:
            return "[...]"

    def arepl(m):
        return m.group(CLOZE_REGEX_MATCH_GROUP_CONTENT)

    for ord in ords:
        s = re.sub(clozeReg % ord, qrepl, string)
        s = re.sub(clozeReg % ".+?", arepl, s)
        strings.append(s)
    strings.append(re.sub(clozeReg % ".+?", arepl, string))

    return strings