"""Agnes Image 2.1 Flash 文生图 / 图生图 / 多图合成的核心逻辑。"""

import base64
import json
import os
import time
import urllib.error
import urllib.request
from pathlib import Path
from uuid import uuid4

from fastapi import HTTPException

API_BASE_URL = os.getenv("AGNES_API_BASE_URL", "https://apihub.agnes-ai.com/v1")
OUTPUT_DIR = Path("output")
MAX_RETRIES = 3
RETRYABLE_STATUS_CODES = {408, 429, 500, 502, 503, 504}
DEFAULT_MODEL = "agnes-image-2.1-flash"
VALID_RATIOS = {"1:1", "3:4", "4:3", "16:9", "9:16", "2:3", "3:2", "21:9"}
RATIO_DIMENSIONS = {
    "1:1": {"1K": "1024x1024", "2K": "2048x2048", "3K": "3072x3072", "4K": "4096x4096"},
    "3:4": {"1K": "864x1152", "2K": "1728x2304", "3K": "2592x3456", "4K": "3456x4608"},
    "4:3": {"1K": "1152x864", "2K": "2304x1728", "3K": "3456x2592", "4K": "4608x3456"},
    "16:9": {"1K": "1312x736", "2K": "2624x1472", "3K": "3936x2208", "4K": "5248x2944"},
    "9:16": {"1K": "736x1312", "2K": "1472x2624", "3K": "2208x3936", "4K": "2944x5248"},
    "2:3": {"1K": "832x1248", "2K": "1664x2496", "3K": "2496x3744", "4K": "3328x4992"},
    "3:2": {"1K": "1248x832", "2K": "2496x1664", "3K": "3744x2496", "4K": "4992x3328"},
    "21:9": {"1K": "1568x672", "2K": "3136x1344", "3K": "4704x2016", "4K": "6272x2688"},
}


def _resolve_size(size: str, ratio: str | None) -> str:
    """把 size 档位 (1K/2K/3K/4K) 配合 ratio 解析成实际像素尺寸，方便保存文件。"""
    if ratio and ratio not in VALID_RATIOS:
        raise HTTPException(status_code=400, detail=f"不支持的宽高比: {ratio}")
    if size in {"1K", "2K", "3K", "4K"}:
        if not ratio:
            ratio = "1:1"
        return RATIO_DIMENSIONS[ratio][size]
    return size


def _build_payload(*, prompt: str, size: str, ratio: str | None, images: list[str] | None) -> dict:
    """组装请求体。注意 response_format 必须放在 extra_body 内。"""
    payload: dict = {
        "model": DEFAULT_MODEL,
        "prompt": prompt,
        "size": size,
    }
    extra_body: dict = {}
    if ratio:
        payload["ratio"] = ratio
    if images:
        extra_body["image"] = images
    if extra_body:
        payload["extra_body"] = extra_body
    return payload


def _post_with_retry(url: str, headers: dict, payload: dict) -> dict:
    """调用 Agnes Image 接口，并对可恢复的上游错误进行指数退避重试。"""
    data = json.dumps(payload).encode("utf-8")
    for attempt in range(1, MAX_RETRIES + 1):
        request = urllib.request.Request(url, data=data, headers=headers, method="POST")
        try:
            with urllib.request.urlopen(request, timeout=360) as response:
                return json.loads(response.read().decode("utf-8"))
        except urllib.error.HTTPError as e:
            if e.code not in RETRYABLE_STATUS_CODES or attempt == MAX_RETRIES:
                body = e.read().decode("utf-8", errors="replace")
                raise HTTPException(status_code=502, detail=f"Agnes 图片服务错误: HTTP {e.code} {body}") from e
        except (urllib.error.URLError, TimeoutError) as e:
            if attempt == MAX_RETRIES:
                raise HTTPException(status_code=504, detail="Agnes 图片服务连接或请求超时") from e
        time.sleep(2 ** (attempt - 1))


def _download_image(url: str) -> bytes:
    """从 URL 或 data URI 下载图片。"""
    if url.startswith("data:image/"):
        try:
            _, encoded = url.split(",", 1)
            return base64.b64decode(encoded, validate=True)
        except (ValueError, TypeError) as e:
            raise HTTPException(status_code=502, detail="图片 data URL 格式无效") from e

    request = urllib.request.Request(url, headers={"User-Agent": "Mozilla/5.0"})
    for attempt in range(1, MAX_RETRIES + 1):
        try:
            with urllib.request.urlopen(request, timeout=120) as response:
                return response.read()
        except urllib.error.HTTPError as e:
            if e.code not in RETRYABLE_STATUS_CODES or attempt == MAX_RETRIES:
                raise HTTPException(status_code=502, detail=f"图片 URL 下载失败: HTTP {e.code}") from e
        except (urllib.error.URLError, TimeoutError) as e:
            if attempt == MAX_RETRIES:
                raise HTTPException(status_code=504, detail="图片 URL 下载超时或网络连接失败") from e
        time.sleep(2 ** (attempt - 1))


def generate_images(
    *,
    prompt: str,
    size: str,
    ratio: str | None,
    images: list[str] | None,
    profile_name: str,
):
    """生成图片并保存到本地，返回结果字典。支持文生图 / 图生图 / 多图合成。"""
    api_key = os.getenv("AGNES_API_KEY")
    if not api_key:
        raise HTTPException(status_code=500, detail="未配置环境变量 AGNES_API_KEY")

    resolved_size = _resolve_size(size, ratio)
    payload = _build_payload(prompt=prompt, size=size, ratio=ratio, images=images)
    headers = {
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    }
    response = _post_with_retry(f"{API_BASE_URL}/images/generations", headers, payload)

    profile_dir = OUTPUT_DIR / profile_name
    profile_dir.mkdir(parents=True, exist_ok=True)
    saved = []
    for item in response.get("data") or []:
        try:
            if item.get("b64_json"):
                raw = base64.b64decode(item["b64_json"], validate=True)
            elif item.get("url"):
                raw = _download_image(item["url"])
            else:
                raise HTTPException(status_code=502, detail="Agnes 图片服务未返回 b64_json 或 url")
        except ValueError as e:
            raise HTTPException(status_code=502, detail="Agnes Base64 图片数据格式无效") from e

        filename = f"{DEFAULT_MODEL}-{uuid4().hex}.png"
        (profile_dir / filename).write_bytes(raw)
        saved.append({"filename": filename, "url": f"/output/{profile_name}/{filename}", "bytes": len(raw)})

    return {"model": DEFAULT_MODEL, "size": resolved_size, "ratio": ratio or "1:1", "images": saved}