from __future__ import annotations

from threading import Thread
from uuid import uuid4

from django.db import transaction
from django.utils import timezone

from review_agent.models import (
    Conversation,
    FileAttachment,
    FileSummaryBatch,
    FileSummaryBatchAttachment,
    Message,
    WorkflowNodeRun,
)

from .events import record_event


NODE_DEFINITIONS = [
    ("upload", "附件固化"),
    ("extract", "压缩包解压"),
    ("inventory", "文件扫描"),
    ("page_count", "页数统计"),
    ("product_detect", "产品识别"),
    ("report", "报告输出"),
    ("complete", "完成"),
]


def build_batch_no() -> str:
    return f"FS-{timezone.localtime().strftime('%Y%m%d%H%M%S')}-{uuid4().hex[:6]}"


@transaction.atomic
def create_file_summary_batch(
    *,
    conversation: Conversation,
    user,
    trigger_message: Message | None = None,
) -> FileSummaryBatch:
    active_attachments = list(
        FileAttachment.objects.select_for_update()
        .filter(conversation=conversation, is_active=True)
        .exclude(upload_status=FileAttachment.UploadStatus.DELETED)
        .order_by("original_name", "-created_at")
    )
    if not active_attachments:
        raise ValueError("当前对话没有可用附件。")

    batch = FileSummaryBatch.objects.create(
        conversation=conversation,
        user=user,
        trigger_message=trigger_message,
        batch_no=build_batch_no(),
    )

    for attachment in active_attachments:
        FileSummaryBatchAttachment.objects.create(batch=batch, attachment=attachment)
        attachment.upload_status = FileAttachment.UploadStatus.BOUND
        attachment.save(update_fields=["upload_status"])

    for code, name in NODE_DEFINITIONS:
        WorkflowNodeRun.objects.create(batch=batch, node_code=code, node_name=name)

    record_event(batch, "workflow_created", {"batch_id": batch.pk, "batch_no": batch.batch_no})
    return batch


class WorkflowExecutor:
    def __init__(self, batch: FileSummaryBatch):
        self.batch = batch

    def run(self) -> None:
        self.batch.status = FileSummaryBatch.Status.RUNNING
        self.batch.started_at = timezone.now()
        self.batch.save(update_fields=["status", "started_at"])
        record_event(self.batch, "workflow_started", {"batch_id": self.batch.pk})

        try:
            for node in self.batch.node_runs.order_by("id"):
                self._run_node(node)
        except Exception as exc:
            self.batch.status = FileSummaryBatch.Status.FAILED
            self.batch.error_message = str(exc)
            self.batch.finished_at = timezone.now()
            self.batch.save(update_fields=["status", "error_message", "finished_at"])
            record_event(self.batch, "workflow_failed", {"message": str(exc)})
            return

        self.batch.status = FileSummaryBatch.Status.SUCCESS
        self.batch.finished_at = timezone.now()
        self.batch.save(update_fields=["status", "finished_at"])
        record_event(self.batch, "workflow_completed", {"batch_id": self.batch.pk})

    def _run_node(self, node: WorkflowNodeRun) -> None:
        now = timezone.now()
        node.status = WorkflowNodeRun.Status.RUNNING
        node.progress = 10
        node.started_at = now
        node.message = f"{node.node_name}处理中"
        node.save(update_fields=["status", "progress", "started_at", "message"])
        record_event(
            self.batch,
            "node_progress",
            {"node_code": node.node_code, "status": node.status, "progress": node.progress},
        )

        node.status = WorkflowNodeRun.Status.SUCCESS
        node.progress = 100
        node.finished_at = timezone.now()
        node.message = f"{node.node_name}完成"
        node.save(update_fields=["status", "progress", "finished_at", "message"])
        record_event(
            self.batch,
            "node_progress",
            {"node_code": node.node_code, "status": node.status, "progress": node.progress},
        )


def start_file_summary_workflow(batch: FileSummaryBatch, *, async_run: bool = True) -> None:
    executor = WorkflowExecutor(batch)
    if not async_run:
        executor.run()
        return
    Thread(target=executor.run, daemon=True).start()