import os
import io
import base64
from typing import List
from pdf2image import convert_from_bytes
from PIL import Image
from openai import OpenAI

MODEL_VISION = os.environ.get("OPENAI_VISION_MODEL", "gpt-4o-mini")
MODEL_TEXT = os.environ.get("OPENAI_TEXT_MODEL", "gpt-4o-mini")

_client = None

def _client_lazy():
    global _client
    if _client is None:
        _client = OpenAI(api_key=os.environ.get("OPENAI_API_KEY"))
    return _client


def _img_to_base64(img: Image.Image) -> str:
    buf = io.BytesIO()
    img.save(buf, format="PNG")
    return base64.b64encode(buf.getvalue()).decode("utf-8")


def _pdf_to_images(pdf_bytes: bytes, dpi: int = 200, max_pages: int = 8) -> List[Image.Image]:
    pages = convert_from_bytes(pdf_bytes, dpi=dpi)
    return pages[:max_pages]


def extract_text_with_openai(payload: bytes, filename: str, filetype: str) -> str:
    """
    画像/PDF: 画像化して Vision (chat.completions) へ。
    txt/docx: テキスト整形だけ実施（安定・低コスト）。
    """
    client = _client_lazy()

    # テキストの場合はそのまま整形
    if filetype not in {"pdf", "image"}:
        text = payload.decode("utf-8", errors="ignore")
        sys = "You clean up Japanese resumes, preserving headings and bullet structure and removing layout noise."
        user = (
            "以下の本文を、見出し・箇条書きを保ちつつ整形してください。不要な罫線/番号/改ページは除去：\n\n" + text
        )
        resp = client.chat.completions.create(
            model=MODEL_TEXT,
            messages=[
                {"role": "system", "content": sys},
                {"role": "user", "content": user},
            ],
            temperature=0.2,
        )
        return resp.choices[0].message.content.strip()

    # 画像/PDF → 画像列へ
    if filetype == "pdf":
        images = _pdf_to_images(payload)
    else:
        images = [Image.open(io.BytesIO(payload)).convert("RGB")]

    vision_msgs = [
        {"role": "system", "content": "You are an accurate Japanese OCR assistant for resumes."},
        {"role": "user", "content": [
            {
                "type": "text",
                "text": "日本語の履歴書/職務経歴書画像です。OCRして本文を日本語テキストで忠実に返してください。"
            },
            *[
                {
                    "type": "image_url",
                    "image_url": {"url": f"data:image/png;base64,{_img_to_base64(img)}"}
                } for img in images
            ]
        ]},
    ]
    resp = client.chat.completions.create(
        model=MODEL_VISION,
        messages=vision_msgs,
        temperature=0.0,
    )
    return resp.choices[0].message.content.strip()


def structure_with_openai(text: str) -> dict:
    client = _client_lazy()
    sys = (
        "あなたは日本語レジュメの構造化アシスタントです。入力テキストからセクションを抽出し、"
        "JSONで返してください。JSONキー: work_experience_raw, education_raw, certifications_raw, skills_list。"
        "skills_list は重複除去済み配列。各 *_raw は原文抜粋で構いません。"
    )
    user = "以下のテキストを解析し、指定のJSONキーで返してください。\n\n" + text
    resp = client.chat.completions.create(
        model=MODEL_TEXT,
        messages=[
            {"role": "system", "content": sys},
            {"role": "user", "content": user},
        ],
        temperature=0.2,
        response_format={"type": "json_object"},
    )
    import json as _json
    try:
        data = _json.loads(resp.choices[0].message.content)
    except Exception:
        data = {"work_experience_raw": text, "education_raw": "", "certifications_raw": "", "skills_list": []}
    for k in ("work_experience_raw", "education_raw", "certifications_raw"):
        data.setdefault(k, "")
    data.setdefault("skills_list", [])
    return data


def summarize_with_openai(text: str) -> dict:
    client = _client_lazy()
    sys = "You write crisp, factual Japanese executive summaries."
    user = (
        "以下の候補者レジュメ本文を、(1)300字、(2)100字、(3)1文 の3粒度で日本語要約してください。"
        "不要な記号は避け、事実を簡潔に述べてください。\n\n" + text
    )
    resp = client.chat.completions.create(
        model=MODEL_TEXT,
        messages=[{"role": "system", "content": sys}, {"role": "user", "content": user}],
        temperature=0.2,
    )
    full = resp.choices[0].message.content.strip()

    # ルールベース簡易抽出（フォーマット崩れでも破綻しない）
    one_sent = full.split("。")[0] + "。" if "。" in full else full
    return {
        "300chars": full[:600],   # だいたい300字相当（マージン確保）
        "100chars": full[:120],
        "onesent": one_sent,
    }