import json
import logging
import time
import uuid

import jsonschema
from django.core.cache import cache
from pathlib import Path

from config.exceptions import AppError
from . import deepseek_client
from .pdf_reader import extract_text_from_pdfs
from prompts.loader import load_prompt

logger = logging.getLogger(__name__)
audit = logging.getLogger('audit')

_SCHEMA_PATH = Path(__file__).resolve().parent.parent / 'schemas' / 'case_full.json'
PARSE_RESULT_TTL = 300  # 5 minutes


def parse_pdf(files, case_type: str, user) -> dict:
    """C1: PDF 解析 → DeepSeek → 结构化数据（不落库，不含评分规则）。"""
    if case_type not in ('traditional', 'teaching'):
        raise AppError('CASE_TYPE_NOT_SUPPORTED', f'case_type 不支持: {case_type}', status_code=400)

    t0 = time.time()

    text = extract_text_from_pdfs(files)

    prompt_name = f'case_{case_type}_full'
    system_prompt, prompt_version = load_prompt(prompt_name)

    result = deepseek_client.call_deepseek(system_prompt, text)
    data = result['data']

    data.pop('scoring_rules', None)
    data.pop('stages', None)

    data['case_type'] = case_type

    _strip_unknown_fields(data)
    _validate_schema(data)

    parse_id = uuid.uuid4().hex[:12]
    cache.set(f'parse_result:{parse_id}', json.dumps(data, ensure_ascii=False), PARSE_RESULT_TTL)

    source = {
        'files': [f.name for f in files],
        'total_bytes': sum(f.size for f in files),
    }

    audit.info(
        'CASE_PARSE user=%s files=%d parse_id=%s tokens=%s prompt_version=%s',
        user.id, len(files), parse_id,
        result.get('usage', {}), prompt_version,
    )

    return {
        'parse_id': parse_id,
        'case_type': case_type,
        'source': source,
        'ai_usage': result.get('usage', {}),
        'prompt_version': prompt_version,
        'parsing_seconds': round(time.time() - t0, 1),
        'data': data,
    }


_SCHEMA_ALLOWED_KEYS = {
    'title', 'case_type', 'difficulty', 'chief_complaint', 'description',
    'patient_age', 'patient_gender', 'tags', 'symptom_tags', 'disease_tags',
    'competency_tags', 'guideline_tags', 'knowledge_points', 'icd_codes',
    'estimated_minutes', 'osce_enabled', 'department_name',
    'traditional', 'teaching',
}


def _strip_unknown_fields(data):
    for key in list(data.keys()):
        if key not in _SCHEMA_ALLOWED_KEYS:
            data.pop(key)


def _validate_schema(data):
    schema = json.loads(_SCHEMA_PATH.read_text(encoding='utf-8'))
    try:
        jsonschema.validate(instance=data, schema=schema)
    except jsonschema.ValidationError as e:
        logger.error('AI parse output schema violation: %s', e.message)
        raise AppError(
            'AI_SCHEMA_VIOLATION',
            f'AI 输出字段不合法: {e.message}',
            status_code=500,
        )