import re
import os.path
import copy
import logging
from werkzeug.utils import cached_property
from piecrust.data.builder import (
        DataBuildingContext, build_page_data, build_layout_data)
from piecrust.data.filters import (
        PaginationFilter, SettingFilterClause, page_value_accessor)
from piecrust.sources.base import PageSource
from piecrust.templating.base import TemplateNotFoundError, TemplatingError


logger = logging.getLogger(__name__)


content_abstract_re = re.compile(r'^<!--\s*(more|(page)?break)\s*-->\s*$',
                                 re.MULTILINE)


class PageRenderingError(Exception):
    pass


class TemplateEngineNotFound(Exception):
    pass


class QualifiedPage(object):
    def __init__(self, page, route, route_metadata):
        self.page = page
        self.route = route
        self.route_metadata = route_metadata

    def getUri(self, sub_num=1):
        return self.route.getUri(self.route_metadata, sub_num=sub_num)

    def __getattr__(self, name):
        return getattr(self.page, name)


class RenderedSegments(object):
    def __init__(self, segments, render_pass_info):
        self.segments = segments
        self.render_pass_info = render_pass_info


class RenderedLayout(object):
    def __init__(self, content, render_pass_info):
        self.content = content
        self.render_pass_info = render_pass_info


class RenderedPage(object):
    def __init__(self, page, uri, num=1):
        self.page = page
        self.uri = uri
        self.num = num
        self.data = None
        self.content = None
        self.render_info = None

    @property
    def app(self):
        return self.page.app

    def copyRenderInfo(self):
        return copy.deepcopy(self.render_info)


PASS_NONE = 0
PASS_FORMATTING = 1
PASS_RENDERING = 2


RENDER_PASSES = [PASS_FORMATTING, PASS_RENDERING]


class RenderPassInfo(object):
    def __init__(self):
        self.used_source_names = set()
        self.used_taxonomy_terms = set()
        self.used_pagination = False
        self.pagination_has_more = False
        self.used_assets = False

    def merge(self, other):
        self.used_source_names |= other.used_source_names
        self.used_taxonomy_terms |= other.used_taxonomy_terms
        self.used_pagination = self.used_pagination or other.used_pagination
        self.pagination_has_more = (self.pagination_has_more or
                                    other.pagination_has_more)
        self.used_assets = self.used_assets or other.used_assets

    def _toJson(self):
        data = {
                'used_source_names': list(self.used_source_names),
                'used_taxonomy_terms': list(self.used_taxonomy_terms),
                'used_pagination': self.used_pagination,
                'pagination_has_more': self.pagination_has_more,
                'used_assets': self.used_assets}
        return data

    @staticmethod
    def _fromJson(data):
        assert data is not None
        rpi = RenderPassInfo()
        rpi.used_source_names = set(data['used_source_names'])
        for i in data['used_taxonomy_terms']:
            terms = i[2]
            if isinstance(terms, list):
                terms = tuple(terms)
            rpi.used_taxonomy_terms.add((i[0], i[1], terms))
        rpi.used_pagination = data['used_pagination']
        rpi.pagination_has_more = data['pagination_has_more']
        rpi.used_assets = data['used_assets']
        return rpi


class PageRenderingContext(object):
    def __init__(self, qualified_page, page_num=1, force_render=False):
        self.page = qualified_page
        self.page_num = page_num
        self.force_render = force_render
        self.pagination_source = None
        self.pagination_filter = None
        self.custom_data = None
        self._current_pass = PASS_NONE

        self.render_passes = {}

    @property
    def app(self):
        return self.page.app

    @property
    def source_metadata(self):
        return self.page.source_metadata

    @cached_property
    def uri(self):
        return self.page.getUri(self.page_num)

    @property
    def current_pass_info(self):
        return self.render_passes.get(self._current_pass)

    def setCurrentPass(self, rdr_pass):
        if rdr_pass != PASS_NONE:
            self.render_passes.setdefault(rdr_pass, RenderPassInfo())
        self._current_pass = rdr_pass

    def setPagination(self, paginator):
        self._raiseIfNoCurrentPass()
        pass_info = self.current_pass_info
        if pass_info.used_pagination:
            raise Exception("Pagination has already been used.")
        assert paginator.is_loaded
        pass_info.used_pagination = True
        pass_info.pagination_has_more = paginator.has_more
        self.addUsedSource(paginator._source)

    def addUsedSource(self, source):
        self._raiseIfNoCurrentPass()
        if isinstance(source, PageSource):
            pass_info = self.current_pass_info
            pass_info.used_source_names.add(source.name)

    def setTaxonomyFilter(self, term_value, *, needs_slugifier=False):
        if not self.page.route.is_taxonomy_route:
            raise Exception("The page for this context is not tied to a "
                            "taxonomy route: %s" % self.uri)

        slugifier = None
        if needs_slugifier:
            slugifier = self.page.route.slugifyTaxonomyTerm
        taxonomy = self.app.getTaxonomy(self.page.route.taxonomy_name)

        flt = PaginationFilter(value_accessor=page_value_accessor)
        flt.addClause(HasTaxonomyTermsFilterClause(
                taxonomy, term_value, slugifier))
        self.pagination_filter = flt

        is_combination = isinstance(term_value, tuple)
        self.custom_data = {
                taxonomy.term_name: term_value,
                'is_multiple_%s' % taxonomy.term_name: is_combination}

    def _raiseIfNoCurrentPass(self):
        if self._current_pass == PASS_NONE:
            raise Exception("No rendering pass is currently active.")


class HasTaxonomyTermsFilterClause(SettingFilterClause):
    def __init__(self, taxonomy, value, slugifier):
        super(HasTaxonomyTermsFilterClause, self).__init__(
                taxonomy.setting_name, value)
        self._taxonomy = taxonomy
        self._slugifier = slugifier
        self._is_combination = isinstance(self.value, tuple)

    def pageMatches(self, fil, page):
        if self._taxonomy.is_multiple:
            # Multiple taxonomy, i.e. it supports multiple terms, like tags.
            page_values = fil.value_accessor(page, self.name)
            if page_values is None or not isinstance(page_values, list):
                return False

            if self._slugifier is not None:
                page_set = set(map(self._slugifier, page_values))
            else:
                page_set = set(page_values)

            if self._is_combination:
                # Multiple taxonomy, and multiple terms to match. Check that
                # the ones to match are all in the page's terms.
                value_set = set(self.value)
                return value_set.issubset(page_set)
            else:
                # Multiple taxonomy, one term to match.
                return self.value in page_set

        # Single taxonomy. Just compare the values.
        page_value = fil.value_accessor(page, self.name)
        if page_value is None:
            return False
        if self._slugifier is not None:
            page_value = self._slugifier(page_value)
        return page_value == self.value


def render_page(ctx):
    eis = ctx.app.env.exec_info_stack
    eis.pushPage(ctx.page, ctx)
    try:
        # Build the data for both segment and layout rendering.
        page_data = _build_render_data(ctx)

        # Render content segments.
        ctx.setCurrentPass(PASS_FORMATTING)
        repo = ctx.app.env.rendered_segments_repository
        save_to_fs = True
        if ctx.app.env.fs_cache_only_for_main_page and not eis.is_main_page:
            save_to_fs = False
        if repo and not ctx.force_render:
            render_result = repo.get(
                    ctx.uri,
                    lambda: _do_render_page_segments(ctx.page, page_data),
                    fs_cache_time=ctx.page.path_mtime,
                    save_to_fs=save_to_fs)
        else:
            render_result = _do_render_page_segments(ctx.page, page_data)
            if repo:
                repo.put(ctx.uri, render_result, save_to_fs)

        # Render layout.
        page = ctx.page
        ctx.setCurrentPass(PASS_RENDERING)
        layout_name = page.config.get('layout')
        if layout_name is None:
            layout_name = page.source.config.get('default_layout', 'default')
        null_names = ['', 'none', 'nil']
        if layout_name not in null_names:
            build_layout_data(page, page_data, render_result['segments'])
            layout_result = _do_render_layout(layout_name, page, page_data)
        else:
            layout_result = {
                    'content': render_result['segments']['content'],
                    'pass_info': None}

        rp = RenderedPage(page, ctx.uri, ctx.page_num)
        rp.data = page_data
        rp.content = layout_result['content']
        rp.render_info = {
                PASS_FORMATTING: RenderPassInfo._fromJson(
                    render_result['pass_info'])}
        if layout_result['pass_info'] is not None:
            rp.render_info[PASS_RENDERING] = RenderPassInfo._fromJson(
                layout_result['pass_info'])
        return rp
    except Exception as ex:
        page_rel_path = os.path.relpath(page.path, ctx.app.root_dir)
        raise Exception("Error rendering page: %s" % page_rel_path) from ex
    finally:
        ctx.setCurrentPass(PASS_NONE)
        eis.popPage()


def render_page_segments(ctx):
    eis = ctx.app.env.exec_info_stack
    eis.pushPage(ctx.page, ctx)
    try:
        ctx.setCurrentPass(PASS_FORMATTING)
        repo = ctx.app.env.rendered_segments_repository
        save_to_fs = True
        if ctx.app.env.fs_cache_only_for_main_page and not eis.is_main_page:
            save_to_fs = False
        if repo and not ctx.force_render:
            render_result = repo.get(
                ctx.uri,
                lambda: _do_render_page_segments_from_ctx(ctx),
                fs_cache_time=ctx.page.path_mtime,
                save_to_fs=save_to_fs)
        else:
            render_result = _do_render_page_segments_from_ctx(ctx)
            if repo:
                repo.put(ctx.uri, render_result, save_to_fs)
    finally:
        ctx.setCurrentPass(PASS_NONE)
        eis.popPage()

    rs = RenderedSegments(
            render_result['segments'],
            RenderPassInfo._fromJson(render_result['pass_info']))
    return rs


def _build_render_data(ctx):
    with ctx.app.env.timerScope("PageDataBuild"):
        data_ctx = DataBuildingContext(ctx.page, page_num=ctx.page_num)
        data_ctx.pagination_source = ctx.pagination_source
        data_ctx.pagination_filter = ctx.pagination_filter
        page_data = build_page_data(data_ctx)
        if ctx.custom_data:
            page_data._appendMapping(ctx.custom_data)
        return page_data


def _do_render_page_segments_from_ctx(ctx):
    page_data = _build_render_data(ctx)
    return _do_render_page_segments(ctx.page, page_data)


def _do_render_page_segments(page, page_data):
    app = page.app

    cpi = app.env.exec_info_stack.current_page_info
    assert cpi is not None
    assert cpi.page == page

    engine_name = page.config.get('template_engine')
    format_name = page.config.get('format')

    engine = get_template_engine(app, engine_name)

    formatted_segments = {}
    for seg_name, seg in page.raw_content.items():
        seg_text = ''
        for seg_part in seg.parts:
            part_format = seg_part.fmt or format_name
            try:
                with app.env.timerScope(engine.__class__.__name__):
                    part_text = engine.renderSegmentPart(
                            page.path, seg_part, page_data)
            except TemplatingError as err:
                err.lineno += seg_part.line
                raise err

            part_text = format_text(app, part_format, part_text)
            seg_text += part_text
        formatted_segments[seg_name] = seg_text

        if seg_name == 'content':
            m = content_abstract_re.search(seg_text)
            if m:
                offset = m.start()
                content_abstract = seg_text[:offset]
                formatted_segments['content.abstract'] = content_abstract

    pass_info = cpi.render_ctx.render_passes.get(PASS_FORMATTING)
    res = {
            'segments': formatted_segments,
            'pass_info': pass_info._toJson()}
    return res


def _do_render_layout(layout_name, page, layout_data):
    cpi = page.app.env.exec_info_stack.current_page_info
    assert cpi is not None
    assert cpi.page == page

    names = layout_name.split(',')
    default_exts = page.app.env.default_layout_extensions
    full_names = []
    for name in names:
        if '.' not in name:
            for ext in default_exts:
                full_names.append(name + ext)
        else:
            full_names.append(name)

    _, engine_name = os.path.splitext(full_names[0])
    engine_name = engine_name.lstrip('.')
    engine = get_template_engine(page.app, engine_name)

    try:
        output = engine.renderFile(full_names, layout_data)
    except TemplateNotFoundError as ex:
        msg = "Can't find template for page: %s\n" % page.path
        msg += "Looked for: %s" % ', '.join(full_names)
        raise Exception(msg) from ex

    pass_info = cpi.render_ctx.render_passes.get(PASS_RENDERING)
    res = {'content': output, 'pass_info': pass_info._toJson()}
    return res


def get_template_engine(app, engine_name):
    if engine_name == 'html':
        engine_name = None
    engine_name = engine_name or app.config.get('site/default_template_engine')
    for engine in app.plugin_loader.getTemplateEngines():
        if engine_name in engine.ENGINE_NAMES:
            return engine
    raise TemplateEngineNotFound("No such template engine: %s" % engine_name)


def format_text(app, format_name, txt, exact_format=False):
    if exact_format and not format_name:
        raise Exception("You need to specify a format name.")

    format_count = 0
    format_name = format_name or app.config.get('site/default_format')
    for fmt in app.plugin_loader.getFormatters():
        if not fmt.enabled:
            continue
        if fmt.FORMAT_NAMES is None or format_name in fmt.FORMAT_NAMES:
            with app.env.timerScope(fmt.__class__.__name__):
                txt = fmt.render(format_name, txt)
            format_count += 1
            if fmt.OUTPUT_FORMAT is not None:
                format_name = fmt.OUTPUT_FORMAT
    if exact_format and format_count == 0:
        raise Exception("No such format: %s" % format_name)
    return txt