background_download

import os
import time
import background_download

dest = os.path.join(os.path.expanduser("~/Documents"), "httpbin.json")

try:
    task_id = background_download.download(
        "https://httpbin.org/json",
        dest,
    )
    print("任务:", task_id)

    for _ in range(30):
        st = background_download.status(task_id)
        print(st.get("state"), st.get("progress"))
        if st.get("state") in ("completed", "failed", "cancelled"):
            break
        time.sleep(1)

    if st.get("state") == "completed":
        print("已保存:", st.get("path"))
    elif st.get("error"):
        print("失败:", st.get("error"))
except background_download.BackgroundDownloadError as exc:
    print("下载失败:", exc, f"code={exc.code}")

import appui
import os
import background_download

DEST = os.path.join(os.path.expanduser("~/Documents"), "demo-download.json")
URL = "https://httpbin.org/json"

state = appui.State(
    task_id="",
    dl_state="空闲",
    progress="—",
    status="点击开始下载",
)


def poll():
    if not state.task_id:
        return
    try:
        st = background_download.status(state.task_id) or {}
        dl_state = st.get("state", "unknown")
        prog = st.get("progress", 0.0)
        state.batch_update(
            dl_state=dl_state,
            progress=f"{float(prog) * 100:.0f}%",
        )
        if dl_state == "completed":
            poll_timer.stop()
            state.status = f"完成: {st.get('path', DEST)}"
        elif dl_state == "failed":
            poll_timer.stop()
            state.status = f"失败: {st.get('error', '未知错误')}"
        elif dl_state == "cancelled":
            poll_timer.stop()
            state.status = "已取消"
    except background_download.BackgroundDownloadError as exc:
        poll_timer.stop()
        state.status = f"查询失败: {exc}"


poll_timer = appui.Timer(interval=0.5, repeats=True, action=poll)


def start_download():
    try:
        task_id = background_download.download(URL, DEST)
        state.batch_update(
            task_id=task_id or "",
            dl_state="running",
            progress="0%",
            status="下载中…",
        )
        poll_timer.start()
    except background_download.BackgroundDownloadError as exc:
        state.status = f"启动失败: {exc}"


def cancel_download():
    if not state.task_id:
        return
    try:
        background_download.cancel(state.task_id)
        poll_timer.stop()
        state.batch_update(dl_state="cancelled", status="已请求取消")
    except background_download.BackgroundDownloadError as exc:
        state.status = f"取消失败: {exc}"


def body():
    return appui.NavigationStack(
        appui.Form([
            appui.Section("任务", [
                appui.LabeledContent("状态", value=state.dl_state),
                appui.LabeledContent("进度", value=state.progress),
                appui.Text(state.task_id or "—")
                .font("caption")
                .foreground_color("secondaryLabel"),
            ]),
            appui.Section("操作", [
                appui.Button("开始后台下载", action=start_download)
                .button_style("bordered_prominent"),
                appui.Button("取消", action=cancel_download, role="destructive"),
                appui.Text(state.status).foreground_color("secondaryLabel"),
            ], footer="需网络；大文件更适合后台下载。"),
        ]).navigation_title("后台下载")
    )


appui.run(body, state=state)

task_id = background_download.download(
    "https://example.com/file.zip",
    "/path/to/save.zip",
)