from __future__ import annotations

import logging
import os
from typing import TYPE_CHECKING, List

from mkdocs import utils
from mkdocs.config import base
from mkdocs.config import config_options as c
from mkdocs.contrib.search.search_index import SearchIndex
from mkdocs.plugins import BasePlugin

if TYPE_CHECKING:
    from mkdocs.config.defaults import MkDocsConfig
    from mkdocs.structure.pages import Page
    from mkdocs.utils.templates import TemplateContext


log = logging.getLogger(__name__)
base_path = os.path.dirname(os.path.abspath(__file__))


class LangOption(c.OptionallyRequired[List[str]]):
    """Validate Language(s) provided in config are known languages."""

    def get_lunr_supported_lang(self, lang):
        fallback = {'uk': 'ru'}
        for lang_part in lang.split("_"):
            lang_part = lang_part.lower()
            lang_part = fallback.get(lang_part, lang_part)
            if os.path.isfile(os.path.join(base_path, 'lunr-language', f'lunr.{lang_part}.js')):
                return lang_part

    def run_validation(self, value: object):
        if isinstance(value, str):
            value = [value]
        if not isinstance(value, list):
            raise c.ValidationError('Expected a list of language codes.')
        for lang in value[:]:
            if lang != 'en':
                lang_detected = self.get_lunr_supported_lang(lang)
                if not lang_detected:
                    log.info(f"Option search.lang '{lang}' is not supported, falling back to 'en'")
                    value.remove(lang)
                    if 'en' not in value:
                        value.append('en')
                elif lang_detected != lang:
                    value.remove(lang)
                    value.append(lang_detected)
                    log.info(f"Option search.lang '{lang}' switched to '{lang_detected}'")
        return value


class _PluginConfig(base.Config):
    lang = c.Optional(LangOption())
    separator = c.Type(str, default=r'[\s\-]+')
    min_search_length = c.Type(int, default=3)
    prebuild_index = c.Choice((False, True, 'node', 'python'), default=False)
    indexing = c.Choice(('full', 'sections', 'titles'), default='full')


class SearchPlugin(BasePlugin[_PluginConfig]):
    """Add a search feature to MkDocs."""

    def on_config(self, config: MkDocsConfig, **kwargs) -> MkDocsConfig:
        """Add plugin templates and scripts to config."""
        if config.theme.get('include_search_page'):
            config.theme.static_templates.add('search.html')
        if not config.theme.get('search_index_only'):
            path = os.path.join(base_path, 'templates')
            config.theme.dirs.append(path)
            if 'search/main.js' not in config.extra_javascript:
                config.extra_javascript.append('search/main.js')  # type: ignore
        if self.config.lang is None:
            # lang setting undefined. Set default based on theme locale
            validate = _PluginConfig.lang.run_validation
            self.config.lang = validate(config.theme.locale.language)
        # The `python` method of `prebuild_index` is pending deprecation as of version 1.2.
        # TODO: Raise a deprecation warning in a future release (1.3?).
        if self.config.prebuild_index == 'python':
            log.info(
                "The 'python' method of the search plugin's 'prebuild_index' config option "
                "is pending deprecation and will not be supported in a future release."
            )
        return config

    def on_pre_build(self, config: MkDocsConfig, **kwargs) -> None:
        """Create search index instance for later use."""
        self.search_index = SearchIndex(**self.config)

    def on_page_context(self, context: TemplateContext, page: Page, **kwargs) -> None:
        """Add page to search index."""
        self.search_index.add_entry_from_context(page)

    def on_post_build(self, config: MkDocsConfig, **kwargs) -> None:
        """Build search index."""
        output_base_path = os.path.join(config.site_dir, 'search')
        search_index = self.search_index.generate_search_index()
        json_output_path = os.path.join(output_base_path, 'search_index.json')
        utils.write_file(search_index.encode('utf-8'), json_output_path)

        assert self.config.lang is not None
        if not config.theme.get('search_index_only'):
            # Include language support files in output. Copy them directly
            # so that only the needed files are included.
            files = []
            if len(self.config.lang) > 1 or 'en' not in self.config.lang:
                files.append('lunr.stemmer.support.js')
            if len(self.config.lang) > 1:
                files.append('lunr.multi.js')
            if 'ja' in self.config.lang or 'jp' in self.config.lang:
                files.append('tinyseg.js')
            for lang in self.config.lang:
                if lang != 'en':
                    files.append(f'lunr.{lang}.js')

            for filename in files:
                from_path = os.path.join(base_path, 'lunr-language', filename)
                to_path = os.path.join(output_base_path, filename)
                utils.copy_file(from_path, to_path)