"""Baidu-hosted UI images. DB stores references; only a bounded RAM cache holds bytes."""
import base64
import hashlib
import re
import secrets
import threading
import time
from collections import OrderedDict
from appearance import png_bytes


class CloudImages:
    def __init__(self, app):
        self.a = app
        self.guard = threading.RLock()
        self.cache = OrderedDict()
        self.limit = 16*1024*1024

    def remember(self, ref, raw):
        with self.guard:
            now=time.monotonic()
            for k,(until,_) in list(self.cache.items()):
                if until<now:self.cache.pop(k)
            self.cache[ref['sha256']] = (now+600,raw)
            self.cache.move_to_end(ref['sha256'])
            while sum(len(v[1]) for v in self.cache.values())>self.limit:self.cache.popitem(last=False)

    def get(self, ref):
        with self.guard:
            found=self.cache.get(ref['sha256'])
            if found and found[0]>time.monotonic():return found[1]
        with self.a.BAIDU.open_file('shared',ref) as response:
            raw=response.read(ref['size']+1)
        if len(raw)!=ref['size'] or hashlib.sha256(raw).hexdigest()!=ref['sha256']:
            raise self.a.Problem('网盘图片校验未通过，请重新上传',502)
        self.remember(ref,raw)
        return raw

    def put(self, value, scope, kind, maximum=2*1024*1024):
        if kind not in ('封面','Logo','图标') or not re.fullmatch(r'[a-f0-9]{16}|platform',scope):
            raise self.a.Problem('图片归属不正确')
        try:raw=png_bytes(value,maximum)
        except ValueError as error:raise self.a.Problem(str(error).replace('Logo',kind))
        a=self.a
        a.BAIDU.token('shared')
        with a.LOCK:
            instance=a.setting('cloud_instance')
            if not instance:instance=secrets.token_hex(8);a.set_setting('cloud_instance',instance)
        digest=hashlib.sha256(raw).hexdigest()
        category='平台外观' if scope=='platform' else '家庭与场所'
        remote='/apps/'+a.BAIDU.public_config()['appFolder']+'/'+category+'/'+instance+'/'+scope+'/'+kind+'/'+digest+'.png'
        md5=hashlib.md5(raw).hexdigest();hashes=[md5]
        pre=a.BAIDU.prepare(remote,len(raw),hashes)
        result=pre.get('existing')
        if not result:
            needed=pre.get('block_list',[0])
            if not isinstance(needed,list) or any(type(i) is not int or i!=0 for i in needed):raise a.Problem('网盘图片分片信息不正确',502)
            if 0 in needed:a.BAIDU.send_block(remote,pre['uploadid'],0,raw,md5)
            result=a.BAIDU.complete(dict(remotePath=remote,size=len(raw),uploadId=pre['uploadid'],hashes=hashes))
        if not result.get('fs_id') or result.get('path')!=remote or result.get('size')!=len(raw):
            raise a.Problem('网盘尚未确认图片，请重试',502)
        ref=dict(provider='baidu',fsId=str(result['fs_id']),remotePath=remote,size=len(raw),sha256=digest,mime='image/png')
        # Verify by reading the remote file before committing the reference, including retries.
        with a.BAIDU.open_file('shared',ref) as response:
            check=response.read(len(raw)+1)
        if check!=raw:raise a.Problem('网盘图片回读校验失败，原有封面未改变',502)
        self.remember(ref,raw)
        return ref

    def migrate_legacy(self):
        """Explicit admin maintenance; replace each reference only after cloud verification."""
        a=self.a;result=[]
        for home in a.objects('households'):
            value=home.get('coverData')
            if not value:continue
            ref=self.put(value,home['id'],'封面')
            with a.LOCK:
                current=a.get_object('households',home['id'])
                if current.get('coverData')!=value:continue
                current.pop('coverData',None);current['coverRef']=ref
                current['profileRevision']=current.get('profileRevision',0)+1
                current['coverRevision']=ref['sha256'][:16];a.save_object('households',current)
            result.append('household:'+home['id'])
        for kind,field in [('Logo','logo'),('图标','icon')]:
            old=a.APPEARANCE.config();value=old.get(field+'Data')
            if not value:continue
            ref=self.put(value,'platform',kind,256*1024)
            with a.LOCK:
                current=a.APPEARANCE.config()
                if current.get(field+'Data')!=value:continue
                current.pop(field+'Data',None);current[field+'Ref']=ref
                current['revision']+=1;a.set_setting('appearance',current)
            result.append('brand:'+field)
        return result