"""Customer uploads: reservation, signed parts, completion.

The operator artwork routes reuse these functions directly with a different
identity, which is why they are plain functions with a session_id argument.
"""
import math
import os
from uuid import UUID, uuid4

from botocore.exceptions import ClientError
from fastapi import APIRouter, Depends, HTTPException

from ..core import db
from ..core.auth import audit, owner, rate_limit
from ..core.limits import upload_limit_bytes
from ..core.models import UploadStart
from ..runtime import PART_BYTES, storage, upload_row

router = APIRouter()

@router.post('/api/uploads')
def begin_upload(body: UploadStart, session_id=Depends(owner)):
    if body.size > upload_limit_bytes():
        raise HTTPException(413, 'File exceeds the malware scan limit; select a smaller file')
    uid = uuid4()
    key = f'originals/{uid}'
    rate_limit('upload-start', str(session_id), 60, 900)
    with db.connect() as c:
        # Serialize reservations across API processes, including changing guest IDs.
        c.execute('SELECT pg_advisory_xact_lock(804208)')
        usage = c.execute('''SELECT COALESCE(sum(size),0) AS total,
            COALESCE(sum(size) FILTER(WHERE owner=%s),0) AS owned,
            count(*) FILTER(WHERE owner=%s AND NOT complete) AS pending
            FROM dtf_local.uploads WHERE purged_at IS NULL''',
            (session_id,session_id)).fetchone()
        if (usage['total']+body.size > int(os.environ.get('STORAGE_QUOTA_BYTES','53687091200')) or
            usage['owned']+body.size > int(os.environ.get('OWNER_UPLOAD_QUOTA_BYTES','10737418240')) or
            usage['pending'] >= int(os.environ.get('MAX_PENDING_UPLOADS','10'))):
            audit('upload_quota_rejected')
            raise HTTPException(429, 'Local storage quota or pending upload limit reached')
        multipart = storage.begin(key)
        c.execute('''INSERT INTO dtf_local.uploads(id,owner,name,size,object_key,multipart_id,expires_at)
            VALUES(%s,%s,%s,%s,%s,%s,now()+interval '1 hour')''',
                  (uid, session_id, body.name, body.size, key, multipart))
    return {'id': uid, 'part_bytes': PART_BYTES}

@router.get('/api/uploads/{uid}')
def upload_status(uid: UUID, session_id=Depends(owner)):
    with db.connect() as c:
        row = upload_row(c, uid, session_id)
    parts = [] if row['complete'] else storage.parts(row['object_key'], row['multipart_id'])
    return {'id': uid, 'complete': row['complete'], 'part_bytes': PART_BYTES,
            'scan_state':row['scan_state'], 'scan_reason':row['scan_reason'],
            'parts': [p['PartNumber'] for p in parts]}

@router.post('/api/uploads/{uid}/parts/{part}')
def part_url(uid: UUID, part: int, session_id=Depends(owner)):
    with db.connect() as c:
        row = upload_row(c, uid, session_id)
    if row['complete'] or not 1 <= part <= math.ceil(row['size'] / PART_BYTES):
        raise HTTPException(409, 'Invalid part or completed upload')
    size = min(PART_BYTES, row['size']-(part-1)*PART_BYTES)
    return {'url': storage.part_url(row['object_key'], row['multipart_id'], part, size)}

@router.post('/api/uploads/{uid}/complete')
def complete_upload(uid: UUID, session_id=Depends(owner)):
    with db.connect() as c:
        row = upload_row(c, uid, session_id, lock=True)
        if row['complete']:
            return {'id': uid, 'complete': True}
        try:
            existing_size = storage.size(row['object_key'])
        except ClientError as exc:
            if exc.response['ResponseMetadata']['HTTPStatusCode'] != 404:
                raise
            existing_size = None
        if existing_size is None:
            parts = storage.parts(row['object_key'], row['multipart_id'])
            expected = math.ceil(row['size'] / PART_BYTES)
            if [p['PartNumber'] for p in parts] != list(range(1, expected+1)) or any(
                p['Size'] != min(PART_BYTES, row['size'] - i*PART_BYTES) for i,p in enumerate(parts)):
                raise HTTPException(409, 'Parts are missing or their sizes do not match')
            storage.complete(row['object_key'], row['multipart_id'], parts)
            existing_size = storage.size(row['object_key'])
        if existing_size != row['size']:
            raise HTTPException(409, 'Stored size differs from declared size')
        c.execute("UPDATE dtf_local.uploads SET complete=true,expires_at=now()+interval '30 days' WHERE id=%s", (uid,))
    return {'id': uid, 'complete': True}

@router.delete('/api/uploads/{uid}')
def cancel_upload(uid: UUID, session_id=Depends(owner)):
    with db.connect() as c:
        row=upload_row(c,uid,session_id,lock=True)
        if row['complete']:
            raise HTTPException(409, 'Completed upload cannot be cancelled')
        storage.discard(row['object_key'],row['multipart_id'],False)
        c.execute('UPDATE dtf_local.uploads SET purged_at=now() WHERE id=%s',(uid,))
    audit('upload_cancelled', upload=str(uid))
    return {'id':uid,'cancelled':True}