#!/usr/bin/env python3
"""Small local DDJ best-result annotator. Python standard library only."""
import argparse
import base64
import binascii
import struct
import zlib
import hashlib
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
import json
import mimetypes
import os
import sys
from pathlib import Path
import re
import tempfile
import threading
from urllib.parse import parse_qs, quote, unquote, urlsplit

APP_DIR = Path(__file__).resolve().parent
sys.path.insert(0, str(APP_DIR.parent))
from dataset_layout import model_directory

STATIC_DIR = APP_DIR / 'static'
SOURCE_RE = re.compile(r'^(?P<id>.+)_source(?P<error>_err)?\.(png|jpe?g|webp)$', re.I)
RESULT_RE = re.compile(r'^(?P<id>.+?)_result(?:_(?P<version>.+))?\.(png|jpe?g|webp)$', re.I)
EDITED_RE = re.compile(r'^(?P<id>.+)_edited(?P<error>_err)?\.(png|jpe?g|webp)$', re.I)
IMAGE_SUFFIXES = {'.png', '.jpg', '.jpeg', '.webp'}
REJECTION_REASONS = {'result_unsatisfied', 'edited_unsatisfied'}


class ReviewError(Exception):
    def __init__(self, message, status=400):
        super().__init__(message)
        self.status = status


def natural_key(value):
    return tuple((0, int(x)) if x.isdigit() else (1, x.lower())
                 for x in re.split(r'(\d+)', value))


class Dataset:
    def __init__(self, root):
        self.root = Path(root).resolve()
        if not self.root.is_dir():
            raise ValueError('数据集目录不存在')
        self.lock = threading.RLock()
        self.records = {}
        self.assets = set()
        self.scan()

    def _inside_file(self, path):
        return path.is_file() and not path.is_symlink() and path.resolve().is_relative_to(self.root)

    def scan(self):
        with self.lock:
            records, assets = {}, set()
            def fail(error):
                raise error
            for directory, folders, files in os.walk(self.root, followlinks=False, onerror=fail):
                parent = Path(directory)
                folders[:] = sorted(x for x in folders
                    if x not in {'.git', '.cache', '__pycache__'} and (parent / x).resolve() != APP_DIR)
                sources, result_groups, edited_groups = {}, {}, {}
                for name in sorted(files):
                    path = parent / name
                    if path.suffix.lower() not in IMAGE_SUFFIXES or not self._inside_file(path):
                        continue
                    match = SOURCE_RE.fullmatch(name)
                    if match:
                        identity = match['id']
                        previous = sources.get(identity)
                        if previous is None or (previous[1] and not match['error']):
                            sources[identity] = (name, bool(match['error']))
                    result = RESULT_RE.fullmatch(name)
                    if result:
                        result_groups.setdefault(result['id'], []).append(
                            {'name': name, 'version': result['version'] or 'original', 'path': path})
                    edited_match = EDITED_RE.fullmatch(name)
                    if edited_match and (edited_match['id'] not in edited_groups or not edited_match['error']):
                        edited_groups[edited_match['id']] = path
                for identity, (source, error) in sources.items():
                    folder = str(parent.relative_to(self.root))
                    model_dir = model_directory(parent, identity)
                    model = str(model_dir.relative_to(self.root)) if model_dir.is_relative_to(self.root) else model_dir.name
                    if model == '.':
                        model = model_dir.name
                    key = hashlib.sha256((folder + '/' + identity).encode()).hexdigest()[:24]
                    results = result_groups.get(identity, [])
                    edited = edited_groups.get(identity)
                    results.sort(key=lambda x: (x['version'] != 'original', natural_key(x['version']), x['name']))
                    record = {'key': key, 'id': identity, 'folder': folder, 'model': model, 'source': parent / source,
                              'source_error': error, 'edited': edited, 'results': results,
                              'best_path': parent / (identity + '_best.txt'),
                              'perfect_path': parent / (identity + '_perfect.txt'),
                              'perfect_image': parent / (identity + '_perfect.png'),
                              'rejected_path': parent / (identity + '_all_rejected.txt')}
                    records[key] = record
                    assets.add(record['source'])
                    assets.add(record['perfect_image'])
                    if edited is not None:
                        assets.add(edited)
                    assets.update(x['path'] for x in results)
            self.records = dict(sorted(records.items(), key=lambda kv: (natural_key(kv[1]['folder']), natural_key(kv[1]['id']))))
            self.assets = assets

    def read_annotation(self, path):
        if path.is_symlink():
            raise ReviewError('标注文件是符号链接，已拒绝访问', 409)
        try:
            data = path.read_bytes()
        except FileNotFoundError:
            return None, 'missing'
        if len(data) > 8192:
            raise ReviewError('标注文件异常，大小超过 8 KB', 409)
        return data.decode('utf-8').strip(), hashlib.sha256(data).hexdigest()

    def annotation_state(self, record):
        best, best_revision = self.read_annotation(record['best_path'])
        rejected, rejected_revision = self.read_annotation(record['rejected_path'])
        # Keep revisions compatible with existing pages until a rejection is saved.
        revision = best_revision if rejected_revision == 'missing' else hashlib.sha256(
            ('best:' + best_revision + '|rejected:' + rejected_revision).encode()).hexdigest()
        perfect, perfect_revision = self.read_annotation(record['perfect_path'])
        image = record['perfect_image']
        if image.is_symlink():
            raise ReviewError('修复图片是符号链接，已拒绝访问', 409)
        image_revision = hashlib.sha256(image.read_bytes()).hexdigest() if image.exists() else 'missing'
        if perfect_revision != 'missing' or image_revision != 'missing':
            revision = hashlib.sha256((revision + '|perfect:' + perfect_revision + '|image:' + image_revision).encode()).hexdigest()
        return best, rejected, revision

    def media(self, path):
        if path is None:
            return None
        try:
            stat = path.stat()
        except FileNotFoundError:
            return None
        relative = str(path.relative_to(self.root))
        return '/media?path=' + quote(relative, safe='') + f'&v={stat.st_mtime_ns}-{stat.st_size}'

    def describe(self, record):
        value, rejected, revision = self.annotation_state(record)
        results = [{'name': x['name'], 'version': x['version'], 'url': self.media(x['path'])}
                   for x in record['results'] if self._inside_file(x['path'])]
        valid = value is not None and value in {x['name'] for x in results}
        perfect, _ = self.read_annotation(record['perfect_path'])
        valid_rejection = rejected in REJECTION_REASONS
        conflict = valid and valid_rejection
        return {'key': record['key'], 'id': record['id'], 'folder': record['folder'], 'model': record['model'],
                'source_url': self.media(record['source']), 'source_error': record['source_error'],
                'edited_url': self.media(record['edited']), 'results': results,
                'best': value if valid and not conflict else None,
                'perfect': perfect if valid and perfect == value and not conflict else None,
                'perfect_url': self.media(record['perfect_image']) if valid and perfect == value and not conflict else None,
                'rejection': rejected if valid_rejection and not conflict else None,
                'invalid_best': bool(value and not valid),
                'invalid_rejection': rejected is not None and not valid_rejection,
                'annotation_conflict': conflict,
                'revision': revision, 'best_file': str(record['best_path'].relative_to(self.root)),
                'rejected_file': str(record['rejected_path'].relative_to(self.root))}

    def state(self):
        with self.lock:
            items = [self.describe(x) for x in self.records.values() if self._inside_file(x['source'])]
            stats = {'total': len(items), 'done': sum(bool(x['best'] or x['rejection']) for x in items),
                     'rejected': sum(x['rejection'] is not None for x in items),
                     'pending': sum(bool(x['results']) and not (x['best'] or x['rejection']) for x in items),
                     'no_results': sum(not x['results'] for x in items)}
            return {'items': items, 'stats': stats, 'dataset': str(self.root)}

    def choose(self, key, result_name, expected_revision, clear=False):
        return self.save_annotation(key, expected_revision, 'clear' if clear else 'best', result_name)

    def reject(self, key, reason, expected_revision):
        if not isinstance(reason, str) or reason not in REJECTION_REASONS:
            raise ReviewError('请选择“结果都不满意”或“edited 不满意”')
        return self.save_annotation(key, expected_revision, 'rejected', reason)

    @staticmethod
    def write_annotation(path, value):
        temporary = None
        try:
            with tempfile.NamedTemporaryFile(mode='w', encoding='utf-8', newline='\n',
                    prefix='.' + path.name + '.', suffix='.tmp', dir=path.parent, delete=False) as stream:
                temporary = Path(stream.name)
                stream.write(value + '\n')
                stream.flush()
                os.fsync(stream.fileno())
            os.replace(temporary, path)
        finally:
            if temporary is not None:
                temporary.unlink(missing_ok=True)

    def save_annotation(self, key, expected_revision, kind, value, png=None):
        with self.lock:
            record = self.records.get(key)
            if record is None or not self._inside_file(record['source']):
                raise ReviewError('条目或 source 已被移除，请刷新目录', 404)
            _, _, revision = self.annotation_state(record)
            if not isinstance(expected_revision, str) or revision != expected_revision:
                raise ReviewError('该标注已在其他页面被修改，请刷新后重试', 409)
            best_path, rejected_path = record['best_path'], record['rejected_path']
            perfect_path, perfect_image = record['perfect_path'], record['perfect_image']
            for path in (best_path, rejected_path, perfect_path, perfect_image):
                if path.parent.resolve() != record['source'].parent.resolve():
                    raise ReviewError('无效的保存目录')
            paths = (best_path, rejected_path, perfect_path, perfect_image)
            previous = {path: path.read_bytes() if path.exists() else None for path in paths}
            try:
                if kind == 'clear':
                    best_path.unlink(missing_ok=True)
                    rejected_path.unlink(missing_ok=True)
                elif kind in {'best', 'perfect', 'repair'}:
                    chosen = next((x for x in record['results'] if x['name'] == value), None)
                    if chosen is None or not self._inside_file(chosen['path']):
                        raise ReviewError('请选择当前条目中存在的 result 图片')
                    if kind == 'repair':
                        image_data = decode_skin_png(png)
                        self.write_bytes(perfect_image, image_data)
                    else:
                        perfect_image.unlink(missing_ok=True)
                    if kind in {'perfect', 'repair'}:
                        self.write_annotation(perfect_path, value)
                    else:
                        perfect_path.unlink(missing_ok=True)
                    self.write_annotation(best_path, value)
                    rejected_path.unlink(missing_ok=True)
                elif kind == 'rejected':
                    if value == 'edited_unsatisfied' and (record['edited'] is None or not self._inside_file(record['edited'])):
                        raise ReviewError('此条目的 edited 图片不存在，请刷新目录')
                    if value == 'result_unsatisfied' and not any(self._inside_file(x['path']) for x in record['results']):
                        raise ReviewError('此条目暂无 result 图片')
                    self.write_annotation(rejected_path, value)
                    best_path.unlink(missing_ok=True)
                else:
                    raise ReviewError('无效的标注操作')
                if kind in {'clear', 'rejected'}:
                    perfect_path.unlink(missing_ok=True)
                    perfect_image.unlink(missing_ok=True)
            except OSError:
                # Restore already-written files if a later write/remove fails.
                for path, data in previous.items():
                    current = path.read_bytes() if path.exists() else None
                    if current != data:
                        if data is None:
                            path.unlink(missing_ok=True)
                        else:
                            self.write_bytes(path, data)
                raise
            return self.describe(record)

    @staticmethod
    def write_bytes(path, value):
        temporary = None
        try:
            with tempfile.NamedTemporaryFile(prefix='.' + path.name, dir=path.parent, delete=False) as stream:
                temporary = Path(stream.name)
                stream.write(value)
                stream.flush()
                os.fsync(stream.fileno())
            os.replace(temporary, path)
        finally:
            if temporary is not None:
                temporary.unlink(missing_ok=True)

    def resolve_media(self, relative):
        path = self.root / relative
        if path not in self.assets or not self._inside_file(path):
            raise ReviewError('图片不存在', 404)
        return path


def decode_skin_png(value):
    """Validate the complete PNG produced by canvas, including CRC and pixel payload."""
    try:
        if not isinstance(value, str) or not value.startswith('data:image/png;base64,'):
            raise ValueError()
        data = base64.b64decode(value.split(',', 1)[1], validate=True)
        if len(data) > 131072 or data[:8] != b'\x89PNG\r\n\x1a\n':
            raise ValueError()
        offset, compressed, channels, ended = 8, bytearray(), None, False
        while offset < len(data):
            size = struct.unpack('>I', data[offset:offset + 4])[0]
            tag = data[offset + 4:offset + 8]
            payload = data[offset + 8:offset + 8 + size]
            crc = struct.unpack('>I', data[offset + 8 + size:offset + 12 + size])[0]
            if zlib.crc32(tag + payload) != crc:
                raise ValueError()
            if offset == 8:
                if tag != b'IHDR' or size != 13:
                    raise ValueError()
                width, height, depth, color, compression, filtering, interlace = struct.unpack('>IIBBBBB', payload)
                if (width, height, depth, compression, filtering, interlace) != (64, 64, 8, 0, 0, 0) or color not in (2, 6):
                    raise ValueError()
                channels = 4 if color == 6 else 3
            elif tag == b'IHDR':
                raise ValueError()
            if tag == b'IDAT':
                compressed.extend(payload)
            offset += size + 12
            if tag == b'IEND':
                if size or offset != len(data):
                    raise ValueError()
                ended = True
                break
        decoder = zlib.decompressobj()
        raw = decoder.decompress(bytes(compressed), 16449)
        if not ended or not decoder.eof or decoder.unused_data or len(raw) != 64 * (64 * channels + 1):
            raise ValueError()
        if any(raw[i] > 4 for i in range(0, len(raw), 64 * channels + 1)):
            raise ValueError()
        return data
    except (ValueError, TypeError, struct.error, zlib.error, binascii.Error):
        raise ReviewError('请提交有效的 64×64 PNG 皮肤')


def make_server(dataset, host, port):
    class Handler(BaseHTTPRequestHandler):
        server_version = 'DDJReview/1.0'

        def send(self, status, data, content_type='application/json; charset=utf-8', cache='no-store'):
            if not isinstance(data, bytes):
                data = json.dumps(data, ensure_ascii=False).encode()
            self.send_response(status)
            self.send_header('Content-Type', content_type)
            self.send_header('Content-Length', str(len(data)))
            self.send_header('Cache-Control', cache)
            self.send_header('X-Content-Type-Options', 'nosniff')
            self.send_header('Referrer-Policy', 'same-origin')
            self.send_header('Content-Security-Policy', "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob:; connect-src 'self'; object-src 'none'; frame-ancestors 'none'")
            self.end_headers()
            self.wfile.write(data)

        def do_GET(self):
            try:
                request = urlsplit(self.path)
                if request.path == '/api/state':
                    return self.send(200, dataset.state())
                if request.path == '/api/health':
                    return self.send(200, {'status': 'ok', 'sources': len(dataset.records)})
                if request.path == '/media':
                    relative = parse_qs(request.query).get('path', [''])[0]
                    with dataset.lock:
                        path = dataset.resolve_media(relative)
                    return self.send(200, path.read_bytes(), mimetypes.guess_type(path.name)[0] or 'application/octet-stream', 'private, max-age=3600')
                name = 'index.html' if request.path == '/' else unquote(request.path).lstrip('/')
                path = (STATIC_DIR / name).resolve()
                if not path.is_relative_to(STATIC_DIR) or not path.is_file():
                    raise ReviewError('文件不存在', 404)
                return self.send(200, path.read_bytes(), mimetypes.guess_type(path.name)[0] or 'application/octet-stream')
            except (ReviewError, OSError, UnicodeError) as error:
                self.send(getattr(error, 'status', 500), {'error': str(error)})

        def do_POST(self):
            try:
                origin = self.headers.get('Origin')
                if origin and urlsplit(origin).netloc != self.headers.get('Host'):
                    raise ReviewError('不允许跨站修改', 403)
                if self.headers.get('X-Annotation-Client') != 'ddj-review':
                    raise ReviewError('缺少客户端标识', 403)
                if self.headers.get_content_type() != 'application/json':
                    raise ReviewError('需要 JSON 请求')
                length = int(self.headers.get('Content-Length', '0'))
                if not 0 <= length <= 200000:
                    raise ReviewError('请求过大', 413)
                body = json.loads(self.rfile.read(length) or b'{}')
                if not isinstance(body, dict):
                    raise ReviewError('无效请求')
                if self.path == '/api/refresh':
                    dataset.scan()
                    return self.send(200, dataset.state())
                if self.path not in {'/api/choose', '/api/clear', '/api/reject', '/api/perfect', '/api/repair'}:
                    raise ReviewError('接口不存在', 404)
                if not isinstance(body.get('key'), str):
                    raise ReviewError('缺少条目编号')
                if self.path in {'/api/perfect', '/api/repair'}:
                    item = dataset.save_annotation(body['key'], body.get('revision'), self.path.rsplit('/', 1)[1], body.get('result'), body.get('png'))
                elif self.path == '/api/reject':
                    item = dataset.reject(body['key'], body.get('reason'), body.get('revision'))
                else:
                    item = dataset.choose(body['key'], body.get('result'), body.get('revision'), self.path == '/api/clear')
                return self.send(200, {'item': item})
            except (ReviewError, OSError, ValueError, UnicodeError) as error:
                self.send(getattr(error, 'status', 400), {'error': str(error)})

    server = ThreadingHTTPServer((host, port), Handler)
    server.daemon_threads = True
    return server


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--root', type=Path, default=APP_DIR.parent)
    parser.add_argument('--host', default='127.0.0.1')
    parser.add_argument('--port', type=int, default=8765)
    args = parser.parse_args()
    dataset = Dataset(args.root)
    server = make_server(dataset, args.host, args.port)
    print(json.dumps({'url': f'http://{args.host}:{server.server_port}', 'root': str(dataset.root),
                      'stats': dataset.state()['stats']}, ensure_ascii=False), flush=True)
    try:
        server.serve_forever()
    except KeyboardInterrupt:
        pass
    finally:
        server.server_close()


if __name__ == '__main__':
    main()