import time
from datetime import UTC, datetime
from typing import Annotated

from fastapi import APIRouter, Depends, HTTPException, Request
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from ..db.base import get_db
from ..db.models import EventConfig, Upload
from ..lib.ids import hash_ip, upload_id
from ..lib.storage import storage
from ..schemas.api import UploadConfirmIn, UploadInitIn

router = APIRouter()

SINGLE_PUT_MAX = 50 * 1024 * 1024
PART_SIZE = 10 * 1024 * 1024
KEY_PREFIX = "uploads"
IP_HASH_SALT = "wedding-uploads-v1"

Db = Annotated[AsyncSession, Depends(get_db)]


def _ext_from(filename: str, mime_type: str) -> str:
    dot = filename.rfind(".")
    if dot >= 0 and dot < len(filename) - 1:
        ext = filename[dot + 1 :].lower()
        if len(ext) <= 6 and ext.isalnum():
            return ext
    return {
        "image/jpeg": "jpg",
        "image/png": "png",
        "image/webp": "webp",
        "image/heic": "heic",
        "image/heif": "heif",
        "image/gif": "gif",
        "video/mp4": "mp4",
        "video/quicktime": "mov",
        "video/webm": "webm",
    }.get(mime_type.lower(), "bin")


def _build_key(uid: str, filename: str, mime: str) -> str:
    now = datetime.now(UTC)
    ext = _ext_from(filename, mime)
    return f"{KEY_PREFIX}/{now.year}/{now.month:02d}/{uid}.{ext}"


def _client_ip(request: Request) -> str:
    h = request.headers
    if cf := h.get("cf-connecting-ip"):
        return cf
    xff = h.get("x-forwarded-for")
    if xff:
        first = xff.split(",")[0].strip()
        if first:
            return first
    if real := h.get("x-real-ip"):
        return real
    return "unknown"


def _now_ms() -> int:
    return int(time.time() * 1000)


@router.post("/init")
async def init_upload(body: UploadInitIn, request: Request, db: Db):
    cfg = (
        await db.execute(select(EventConfig).where(EventConfig.id == 1))
    ).scalar_one_or_none()
    if not cfg:
        raise HTTPException(500, detail="not_configured")

    is_video = body.mimeType.startswith("video/")
    if is_video and not cfg.allow_video:
        raise HTTPException(400, detail="video_not_allowed")
    if body.sizeBytes > cfg.max_file_mb * 1024 * 1024:
        raise HTTPException(
            400, detail={"error": "file_too_large", "maxFileMb": cfg.max_file_mb}
        )
    if (
        is_video
        and body.durationSeconds is not None
        and body.durationSeconds > cfg.max_video_seconds
    ):
        raise HTTPException(
            400,
            detail={
                "error": "video_too_long",
                "maxVideoSeconds": cfg.max_video_seconds,
            },
        )

    uid = upload_id()
    key = _build_key(uid, body.filename, body.mimeType)
    ip_h = hash_ip(_client_ip(request), IP_HASH_SALT)

    if body.sizeBytes <= SINGLE_PUT_MAX:
        presigned = storage.presign_put(key, body.mimeType, expires_in=900)
        db.add(
            Upload(
                id=uid,
                storage_key=key,
                mime_type=body.mimeType,
                size_bytes=body.sizeBytes,
                duration_seconds=body.durationSeconds,
                author_name=(body.authorName or "").strip() or None,
                message=(body.message or "").strip() or None,
                status="pending",
                source="guest",
                ip_hash=ip_h,
                created_at=_now_ms(),
            )
        )
        await db.commit()
        return {
            "uploadId": uid,
            "storageKey": key,
            "mode": "single",
            "putUrl": presigned["url"],
            "putHeaders": presigned["headers"],
        }

    part_count = (body.sizeBytes + PART_SIZE - 1) // PART_SIZE
    multipart = await storage.init_multipart(
        key, body.mimeType, part_count, expires_in=3600 * 6
    )

    db.add(
        Upload(
            id=uid,
            storage_key=key,
            mime_type=body.mimeType,
            size_bytes=body.sizeBytes,
            duration_seconds=body.durationSeconds,
            author_name=(body.authorName or "").strip() or None,
            message=(body.message or "").strip() or None,
            status="pending",
            source="guest",
            ip_hash=ip_h,
            provider_upload_id=multipart["upload_id"],
            created_at=_now_ms(),
        )
    )
    await db.commit()

    return {
        "uploadId": uid,
        "storageKey": key,
        "mode": "multipart",
        "multipart": {
            "providerUploadId": multipart["upload_id"],
            "partSize": multipart["part_size"],
            "partUrls": multipart["part_urls"],
        },
    }


@router.post("/{upload_id}/confirm")
async def confirm_upload(upload_id: str, body: UploadConfirmIn, db: Db):
    row = (
        await db.execute(select(Upload).where(Upload.id == upload_id))
    ).scalar_one_or_none()
    if not row:
        raise HTTPException(404, detail="not_found")
    if row.status == "approved":
        return {"ok": True, "alreadyApproved": True}

    cfg = (
        await db.execute(select(EventConfig).where(EventConfig.id == 1))
    ).scalar_one_or_none()
    if not cfg:
        raise HTTPException(500, detail="not_configured")

    if body.multipart:
        if body.multipart.providerUploadId != row.provider_upload_id:
            raise HTTPException(400, detail="multipart_mismatch")
        await storage.complete_multipart(
            row.storage_key,
            body.multipart.providerUploadId,
            [{"partNumber": p.partNumber, "etag": p.etag} for p in body.multipart.parts],
        )

    head = await storage.head(row.storage_key)
    if head is None:
        raise HTTPException(400, detail="not_uploaded")

    final_status = "pending" if cfg.moderation == "pre" else "approved"
    row.status = final_status
    row.approved_at = _now_ms() if final_status == "approved" else None
    await db.commit()
    return {"ok": True, "status": final_status}


@router.post("/{upload_id}/abort")
async def abort_upload(upload_id: str, db: Db):
    row = (
        await db.execute(select(Upload).where(Upload.id == upload_id))
    ).scalar_one_or_none()
    if not row:
        raise HTTPException(404, detail="not_found")
    if row.provider_upload_id:
        await storage.abort_multipart(row.storage_key, row.provider_upload_id)
    await db.delete(row)
    await db.commit()
    return {"ok": True}