from typing import AsyncIterator

import anyio
from fastapi import APIRouter, Depends, Header, Response, status
from fastapi.responses import FileResponse, StreamingResponse

from app.api.dependencies import get_file_service, get_repair_service
from app.schemas.file import (
    DeletedFileSummary,
    FileDetailResponse,
    FilePlacementBackendSummary,
    FileMutationResponse,
    FileReplicaSummary,
    FileSummary,
    MoveFileRequest,
    PreviewArtifactSummary,
    RecycleBinResponse,
    RenameFileRequest,
)
from app.services.file_service import FileService
from app.schemas.repair import RepairFileResponse
from app.services.repair_service import RepairService

router = APIRouter()


@router.get("/recycle-bin", response_model=RecycleBinResponse)
async def list_recycle_bin(
    service: FileService = Depends(get_file_service),
) -> RecycleBinResponse:
    items = await service.list_deleted_files()
    return RecycleBinResponse(
        items=[DeletedFileSummary.model_validate(item, from_attributes=True) for item in items]
    )


@router.delete("/{file_id}", response_model=FileMutationResponse)
async def delete_file(
    file_id: str,
    service: FileService = Depends(get_file_service),
) -> FileMutationResponse:
    file_entry = await service.delete_file(file_id)
    return FileMutationResponse(file=DeletedFileSummary.model_validate(file_entry, from_attributes=True))


@router.post("/{file_id}/rename", response_model=FileMutationResponse)
async def rename_file(
    file_id: str,
    payload: RenameFileRequest,
    service: FileService = Depends(get_file_service),
) -> FileMutationResponse:
    file_entry = await service.rename_file(file_id=file_id, name=payload.name)
    return FileMutationResponse(file=FileSummary.model_validate(file_entry, from_attributes=True))


@router.post("/{file_id}/move", response_model=FileMutationResponse)
async def move_file(
    file_id: str,
    payload: MoveFileRequest,
    service: FileService = Depends(get_file_service),
) -> FileMutationResponse:
    file_entry = await service.move_file(file_id=file_id, target_parent_id=payload.target_parent_id)
    return FileMutationResponse(file=FileSummary.model_validate(file_entry, from_attributes=True))


@router.post("/{file_id}/restore", response_model=FileMutationResponse)
async def restore_file(
    file_id: str,
    service: FileService = Depends(get_file_service),
) -> FileMutationResponse:
    file_entry = await service.restore_file(file_id)
    return FileMutationResponse(file=FileSummary.model_validate(file_entry, from_attributes=True))


@router.post("/{file_id}/reconcile", response_model=RepairFileResponse)
async def reconcile_file(
    file_id: str,
    service: RepairService = Depends(get_repair_service),
) -> RepairFileResponse:
    enqueued = await service.enqueue_repairs_for_file(file_id)
    return RepairFileResponse(file_id=file_id, enqueued_jobs=enqueued)


@router.get("/{file_id}", response_model=FileDetailResponse)
async def get_file_detail(
    file_id: str,
    service: FileService = Depends(get_file_service),
) -> FileDetailResponse:
    file_entry, artifacts, replicas, decision = await service.get_file_detail(file_id)
    replica_items = [
        FileReplicaSummary(
            id=replica.id,
            blob_id=replica.blob_id,
            backend_id=backend.id,
            backend_name=backend.name,
            backend_type=backend.type,
            backend_stability_class=backend.stability_class,
            backend_enabled=backend.is_enabled,
            storage_key=replica.storage_key,
            status=replica.status,
            size_bytes=replica.size_bytes,
            checksum=replica.checksum,
            etag=replica.etag,
            last_verified_at=replica.last_verified_at,
            created_at=replica.created_at,
            updated_at=replica.updated_at,
        )
        for replica, backend in replicas
    ]
    ready_replica_backend_ids = sorted({item.backend_id for item in replica_items if item.status == "ready"})
    desired_backend_ids = [backend.id for backend in (decision.backends if decision is not None else [])]
    return FileDetailResponse(
        file=FileSummary.model_validate(file_entry, from_attributes=True),
        preview_artifacts=[
            PreviewArtifactSummary.model_validate(artifact, from_attributes=True) for artifact in artifacts
        ],
        replicas=replica_items,
        placement_file_class=decision.file_class if decision is not None else None,
        desired_backends=[
            FilePlacementBackendSummary.model_validate(backend, from_attributes=True)
            for backend in (decision.backends if decision is not None else [])
        ],
        ready_replica_backend_ids=ready_replica_backend_ids,
        missing_backend_ids=[backend_id for backend_id in desired_backend_ids if backend_id not in ready_replica_backend_ids],
    )


@router.get("/{file_id}/download")
async def download_file(
    file_id: str,
    service: FileService = Depends(get_file_service),
) -> FileResponse:
    file_entry, file_path = await service.resolve_download(file_id)
    return FileResponse(
        path=file_path,
        filename=file_entry.name,
        media_type=file_entry.mime_type or "application/octet-stream",
    )


@router.get("/{file_id}/preview")
async def preview_file(
    file_id: str,
    service: FileService = Depends(get_file_service),
) -> FileResponse:
    file_entry, file_path = await service.resolve_preview(file_id)
    return FileResponse(
        path=file_path,
        filename=file_entry.name,
        media_type=file_entry.mime_type or "application/octet-stream",
        content_disposition_type="inline",
    )


@router.get("/{file_id}/stream")
async def stream_file(
    file_id: str,
    range_header: str | None = Header(default=None, alias="Range"),
    service: FileService = Depends(get_file_service),
) -> Response:
    stream_result = await service.resolve_stream(file_id, range_header)
    chunk_size = 64 * 1024

    async def body_iter() -> AsyncIterator[bytes]:
        remaining = stream_result.end - stream_result.start + 1
        async with await anyio.open_file(stream_result.file_path, "rb") as file_handle:
            await file_handle.seek(stream_result.start)
            while remaining > 0:
                chunk = await file_handle.read(min(chunk_size, remaining))
                if not chunk:
                    break
                remaining -= len(chunk)
                yield chunk

    headers = {
        "Accept-Ranges": "bytes",
        "Content-Length": str(stream_result.end - stream_result.start + 1),
    }
    status_code = status.HTTP_200_OK
    if range_header:
        headers["Content-Range"] = f"bytes {stream_result.start}-{stream_result.end}/{stream_result.file_size}"
        status_code = status.HTTP_206_PARTIAL_CONTENT

    return StreamingResponse(
        body_iter(),
        status_code=status_code,
        headers=headers,
        media_type=stream_result.file_entry.mime_type or "application/octet-stream",
    )