#!/usr/bin/env python3
"""Build the standalone CS-Notes website from the published Markdown source."""
from __future__ import annotations

import argparse
import hashlib
import html
import json
import posixpath
import re
import shutil
import tempfile
import urllib.parse
from pathlib import Path

from site_assets import copy_referenced_assets, optimize_images, write_manifest, write_search_index
from check import check

BASE = Path(__file__).resolve().parents[1]
ROOT = BASE / 'upstream'
SITE = BASE / 'templates'
DIST = BASE / 'dist'
CACHE = BASE / '.cache/site-assets'
VERSION_FILE = BASE / 'source-version.json'
SOURCE_COMMIT = json.loads(VERSION_FILE.read_text())['commit'] if VERSION_FILE.is_file() else 'unknown'
IMAGE_BY_NAME = {}
SOURCE_IMAGE_HOST = 'cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com'
IMAGE = re.compile(r'(<img\b[^>]*?\bsrc=["\'])([^"\']+)(["\'])', re.I)
MD_IMAGE = re.compile(r'(!\[[^\]]*\]\()((?:[^()\s]|\([^()\n]*\))*)(\))')
MD_LINK = re.compile(r'(?<!!)\[([^\]]+)\]\(([^\s)]+)\)')
HTML_LINK = re.compile(r'(<a\b[^>]*?\bhref=["\'])([^"\']+)(["\'])', re.I)


def sources():
    return [ROOT / 'README.md', ROOT / 'CONTRIBUTING.md',
            *sorted((ROOT / 'notes').glob('*.md')),
            *sorted((ROOT / 'assets').glob('*.md'))]


def image_urls():
    found = set()
    for path in sources():
        text = re.sub(r'```[^\n]*\n[\s\S]*?```|<!--[\s\S]*?-->', '', path.read_text())
        for pattern in (IMAGE, MD_IMAGE):
            for match in pattern.finditer(text):
                url = html.unescape(match[2].strip())
                if url.startswith(('https://', 'http://')):
                    found.add(url)
    return sorted(found)


def repository_images():
    result = {}
    for directory in ('notes/pics', 'assets', 'docs/_media'):
        for path in (ROOT / directory).rglob('*'):
            if path.is_file():
                result.setdefault(path.name, []).append(path)
    return result


def local_target(url, source, html_link=False):
    url = html.unescape(url)
    parsed = urllib.parse.urlsplit(url)
    path = urllib.parse.unquote(parsed.path)
    if parsed.netloc.lower() in ('github.com', 'www.github.com'):
        prefix = '/CyC2018/CS-Notes/blob/master/'
        if path.startswith(prefix):
            path = path[len(prefix):]
        else:
            return url
    elif parsed.hostname == SOURCE_IMAGE_HOST:
        candidates = IMAGE_BY_NAME.get(Path(path).name, [])
        if len(candidates) != 1:
            return url
        path = candidates[0].relative_to(ROOT).as_posix()
    elif parsed.netloc:
        return url
    elif not path or url.startswith(('#', 'mailto:', 'data:', '//')):
        return url
    elif not path.startswith('/'):
        path = posixpath.normpath(str(source.relative_to(ROOT).parent / path))
    path = path.lstrip('/')
    if not (ROOT / path).resolve().is_relative_to(ROOT.resolve()) or not (ROOT / path).is_file():
        return url
    if path.endswith('.md'):
        if not html_link:
            result = '/' + urllib.parse.quote(path, safe='/')
            if parsed.fragment:
                result += '#' + urllib.parse.quote(urllib.parse.unquote(parsed.fragment), safe='')
            return result
        if path == 'README.md':
            route = '/'
        else:
            route = '/' + urllib.parse.quote(path[:-3], safe='/')
        if parsed.fragment:
            route += '?id=' + urllib.parse.quote(urllib.parse.unquote(parsed.fragment), safe='')
        return '/#' + route
    return '/' + urllib.parse.quote(path, safe='/')


def render_markdown(path):
    content = path.read_text()
    def image(match):
        url = html.unescape(match[2].strip())
        parsed = urllib.parse.urlsplit(url)
        if parsed.path and not parsed.scheme and not parsed.netloc:
            candidate = (ROOT / urllib.parse.unquote(parsed.path).lstrip('/')) if parsed.path.startswith('/') else (path.parent / urllib.parse.unquote(parsed.path))
            if not candidate.resolve().is_relative_to(ROOT.resolve()) or not candidate.is_file():
                raise ValueError('Missing source image: ' + parsed.path)
        url = local_target(url, path)
        return match[1] + url + match[3]
    def convert(part):
        part = IMAGE.sub(image, part)
        part = MD_IMAGE.sub(image, part)
        part = MD_LINK.sub(lambda m: f'[{m[1]}]({local_target(m[2], path)})', part)
        return HTML_LINK.sub(lambda m: m[1] + local_target(m[2], path, html_link=True) + m[3], part)
    parts = re.split(r'(```[^\n]*\n[\s\S]*?```|<!--[\s\S]*?-->)', content)
    return ''.join(part if i % 2 else convert(part) for i, part in enumerate(parts))


def build(optimize=True):
    global IMAGE_BY_NAME
    IMAGE_BY_NAME = repository_images()
    external = image_urls()
    replacements = {url: local_target(url, ROOT / 'README.md') for url in external}
    reused = {url: path for url, path in replacements.items() if path.startswith('/')}
    unchanged_external = [url for url, path in replacements.items() if not path.startswith('/')]
    with tempfile.TemporaryDirectory(prefix='.site-build-', dir=DIST.parent) as temporary:
        dist = Path(temporary) / 'dist'
        dist.mkdir()
        shutil.copytree(SITE / 'vendor', dist / 'vendor')
        for name in ('index.html', 'site.css', 'site.js', 'search.js'):
            shutil.copyfile(SITE / name, dist / name)
        for path in sources():
            target = dist / path.relative_to(ROOT)
            target.parent.mkdir(parents=True, exist_ok=True)
            target.write_text(render_markdown(path))
        homepage = (dist / 'README.md').read_text()
        emojis = {'pencil2': '✏️', 'computer': '💻', 'cloud': '☁️', 'floppy_disk': '💾',
                  'coffee': '☕', 'bulb': '💡', 'art': '🎨', 'wrench': '🔧',
                  'watermelon': '🍉', 'memo': '📝'}
        for name, symbol in emojis.items():
            homepage = re.sub(r'^(## ):' + name + r':\s*', r'\1', homepage, flags=re.M)
            homepage = homepage.replace('#' + name + '-', '#')
            homepage = homepage.replace(':' + name + ':', symbol)
        topics = [('算法', '✏️'), ('操作系统', '💻'), ('网络', '☁️'), ('面向对象', '🎨'),
                  ('数据库', '💾'), ('Java', '☕'), ('系统设计', '💡'), ('工具', '🔧'),
                  ('后记', '📝')]
        cards = '<nav class="topic-grid" aria-label="笔记分类">' + ''.join(
            f'<a href="/#/?id={urllib.parse.quote(label.lower())}"><span aria-hidden="true">{symbol}</span>{label}</a>'
            for label, symbol in topics) + '</nav>'
        homepage = re.sub(r'^\| 算法[^\n]*\n\|[^\n]*\n\|[^\n]*', cards, homepage, count=1, flags=re.M)
        homepage = homepage.replace('width="200px"', 'class="site-logo" width="200px"', 1)
        (dist / 'README.md').write_text('# CS-Notes\n\n' + homepage)
        note_paths = ['/' + str(p.relative_to(ROOT).with_suffix('')) for p in sorted((ROOT / 'notes').glob('*.md'))]
        sidebar = ['- [首页](/)', '- [面试高频问题](/notes/面试高频问题)', '']
        for line in homepage.splitlines():
            if line.startswith('## '):
                label = re.sub(r':[a-z0-9_]+:', '', line[3:]).strip()
                if label == '后记':
                    break
                sidebar.extend(['', '- **' + label + '**'])
            elif line.startswith('- ['):
                sidebar.append('  ' + line)
        (dist / '_sidebar.md').write_text('\n'.join(sidebar) + '\n')
        (dist / '_404.md').write_text('# 页面暂未找到\n\n请从目录或搜索查找笔记。\n\n[返回首页](/)\n')
        (dist / '.nojekyll').touch()
        shutil.copyfile(ROOT / 'docs/_media/LogoMakr_1J56bI.png', dist / 'favicon.png')
        copy_referenced_assets(dist, ROOT)
        image_report = optimize_images(dist, CACHE) if optimize else {'converted': 0}
        index_name, search_report = write_search_index(dist, sorted((dist / 'notes').glob('*.md')))
        legacy = json.loads((SITE / 'legacy-routes.json').read_text())
        (dist / 'search-paths.js').write_text(
            'window.CS_NOTES_PATHS = ' + json.dumps(note_paths, ensure_ascii=False) + ';\n'
            'window.CS_NOTES_LEGACY_ROUTES = ' + json.dumps(legacy, ensure_ascii=False, separators=(',', ':')) + ';\n'
            'window.CS_NOTES_SEARCH_INDEX = "/' + index_name + '";\n')
        generator = hashlib.sha256()
        for resource in sorted([*Path(__file__).parent.glob('*.py'), *SITE.rglob('*')]):
            if resource.is_file():
                generator.update(resource.relative_to(BASE).as_posix().encode())
                generator.update(resource.read_bytes())
        build_info = {'sourceCommit': SOURCE_COMMIT, 'generatorHash': generator.hexdigest(), 'notes': len(note_paths),
                      'searchIndex': index_name, 'legacyRoutes': len(legacy)}
        (dist / 'build-info.json').write_text(json.dumps(build_info, indent=2) + '\n')
        entry = (dist / 'index.html').read_text()
        for name in ('site.css', 'site.js', 'search.js', 'search-paths.js'):
            digest = hashlib.sha256((dist / name).read_bytes()).hexdigest()[:12]
            entry = entry.replace('/' + name + '"', '/' + name + '?v=' + digest + '"')
        (dist / 'index.html').write_text(entry)
        write_manifest(dist, build_info)
        files = [p for p in dist.rglob('*') if p.is_file()]
        report = {'notes': len(note_paths), 'files': len(files), 'bytes': sum(p.stat().st_size for p in files),
                  'oversized': [str(p.relative_to(dist)) for p in files if p.stat().st_size > 25*1024*1024],
                  'repositoryImagesUsedForOldUrls': len(reused), 'externalImages': len(unchanged_external), 'search': search_report, 'images': image_report, 'legacyRoutes': len(legacy)}
        if report['oversized'] or len(files) > 20000:
            raise ValueError('Static hosting quota exceeded')
        validation = check(ROOT, dist)
        if validation['errors']:
            raise ValueError('Static site validation failed: ' + '; '.join(validation['errors']))
        previous = Path(temporary) / 'previous'
        if DIST.exists():
            DIST.rename(previous)
        try:
            dist.rename(DIST)
        except BaseException:
            if previous.exists():
                previous.rename(DIST)
            raise
    report.update({'sourceCommit': SOURCE_COMMIT, 'imageReplacements': reused, 'externalImageUrls': unchanged_external})
    DIST.with_name(DIST.name + '-report.json').write_text(json.dumps(report, ensure_ascii=False, indent=2) + '\n')
    print(json.dumps({k: v for k, v in report.items() if k not in ('imageReplacements', 'externalImageUrls')}, ensure_ascii=False, indent=2))


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='仅在本机从最新上游源码生成静态站，不下载图片、不发布。')
    parser.add_argument('--source', type=Path, default=ROOT)
    parser.add_argument('--output', type=Path, default=DIST)
    parser.add_argument('--source-commit', default=SOURCE_COMMIT)
    parser.add_argument('--no-optimize-images', action='store_true')
    args = parser.parse_args()
    ROOT, DIST, SOURCE_COMMIT = args.source.resolve(), args.output.resolve(), args.source_commit
    if not ROOT.is_dir():
        parser.error("源码目录不存在，请先运行 website/refresh.py。")
    if ROOT == DIST or ROOT.is_relative_to(DIST) or DIST.is_relative_to(ROOT):
        parser.error('源码和输出目录必须相互独立。')
    if not DIST.is_relative_to(BASE):
        parser.error('本地验证输出必须保存在当前验证目录中。')
    build(optimize=not args.no_optimize_images)