from __future__ import annotations

from dataclasses import dataclass, field
from pathlib import Path

from review_agent.models import Conversation, FileAttachment, FileSummaryBatch, FileSummaryItem


@dataclass
class InstructionInputSelection:
    status: str
    file_name: str = ""
    storage_path: str = ""
    attachment: FileAttachment | None = None
    source_summary_batch: FileSummaryBatch | None = None
    source_summary_item_id: int | None = None
    candidates: list[str] = field(default_factory=list)
    message: str = ""


def select_instruction_input(conversation: Conversation, message: str) -> InstructionInputSelection:
    candidates = _active_docx_attachments(conversation)
    named = _match_by_message(candidates, message)
    if len(named) == 1:
        return _selection_from_attachment(named[0])
    instruction_candidates = [item for item in candidates if "说明书" in item.original_name]
    if len(instruction_candidates) == 1:
        return _selection_from_attachment(instruction_candidates[0])
    if len(candidates) == 1:
        return _selection_from_attachment(candidates[0])
    if len(instruction_candidates) > 1 or len(candidates) > 1:
        names = [item.original_name for item in (instruction_candidates or candidates)]
        return InstructionInputSelection(
            status="waiting_user",
            candidates=names,
            message="请确认用于生成第1章监管信息的说明书文件名：" + "、".join(names),
        )
    summary_selection = _select_from_latest_summary(conversation, message)
    if summary_selection:
        return summary_selection
    return InstructionInputSelection(status="missing", message="请先上传产品说明书 docx 文件。")


def _active_docx_attachments(conversation: Conversation) -> list[FileAttachment]:
    return list(
        FileAttachment.objects.filter(
            conversation=conversation,
            is_active=True,
        )
        .exclude(upload_status=FileAttachment.UploadStatus.DELETED)
        .filter(original_name__iendswith=".docx")
        .order_by("original_name", "-version_no")
    )


def _match_by_message(candidates: list[FileAttachment], message: str) -> list[FileAttachment]:
    compact = "".join((message or "").lower().split())
    matched = []
    for attachment in candidates:
        stem = Path(attachment.original_name).stem.lower()
        name = attachment.original_name.lower()
        if stem and stem in compact or name and name in compact:
            matched.append(attachment)
    return matched


def _selection_from_attachment(attachment: FileAttachment) -> InstructionInputSelection:
    return InstructionInputSelection(
        status="selected",
        file_name=attachment.original_name,
        storage_path=attachment.storage_path,
        attachment=attachment,
    )


def _select_from_latest_summary(conversation: Conversation, message: str) -> InstructionInputSelection | None:
    batch = (
        FileSummaryBatch.objects.filter(conversation=conversation, status=FileSummaryBatch.Status.SUCCESS)
        .order_by("-finished_at", "-created_at", "-id")
        .first()
    )
    if not batch:
        return None
    items = list(batch.items.filter(file_name__iendswith=".docx").order_by("file_name", "id"))
    compact = "".join((message or "").lower().split())
    named = [item for item in items if Path(item.file_name).stem.lower() in compact or item.file_name.lower() in compact]
    candidates = named or [item for item in items if "说明书" in item.file_name]
    if len(candidates) == 1:
        item = candidates[0]
        return InstructionInputSelection(
            status="selected",
            file_name=item.file_name,
            storage_path=item.storage_path,
            source_summary_batch=batch,
            source_summary_item_id=item.pk,
        )
    if len(candidates) > 1:
        return InstructionInputSelection(
            status="waiting_user",
            source_summary_batch=batch,
            candidates=[item.file_name for item in candidates],
            message="请确认用于生成第1章监管信息的说明书文件名：" + "、".join(item.file_name for item in candidates),
        )
    return None