"""Read-only output discovery, history preservation and small runtime snapshots."""
import glob
import hashlib
import json
import os
from pathlib import Path
import shutil
import subprocess
from .artifacts import files_under


def outputs(patterns):
    paths = []
    for pattern in patterns:
        expanded = glob.iglob(pattern) if glob.has_magic(pattern) else [pattern]
        for name in expanded:
            path = Path(name)
            if path.is_symlink():
                continue
            if path.is_file():paths.append(path)
            elif path.is_dir():paths.extend(files_under([path], limit=4097))
            if len(paths) > 4096:
                raise ValueError("原输出文件超过 4096 项，请收窄登记输出范围")
    return sorted(set(paths))


def preserve(paths, directory, maximum=64 * 1024**3):
    sizes = [path.stat().st_size for path in paths]
    total = sum(sizes)
    if total > maximum or shutil.disk_usage(directory).free < total + 10 * 1024**3:
        raise ValueError("保护原有同名结果所需空间不足或超过 64 GiB，本次未启动")
    destination = directory / "previous-outputs"
    destination.mkdir(mode=0o700)
    manifest = []
    for path in paths:
        identity = hashlib.sha256(str(path).encode()).hexdigest()
        target = destination / identity
        before = path.stat()
        with path.open("rb") as source, target.open("xb") as output:
            shutil.copyfileobj(source, output, length=1024 * 1024)
        after = path.stat()
        if (before.st_size, before.st_mtime_ns) != (after.st_size, after.st_mtime_ns):
            raise ValueError("原输出仍被其他任务写入，请等待后再试")
        manifest.append({"path": str(path), "backup": identity, "size": before.st_size})
    (destination / "manifest.json").write_text(json.dumps(manifest, ensure_ascii=False, indent=2), encoding="utf-8")
    return len(manifest)


def runtime_snapshot():
    result = {"containers": [], "tmux_sessions": [], "errors": []}
    try:
        raw = subprocess.run(["/usr/bin/docker", "ps", "-a", "--format", "{{json .}}"], capture_output=True, timeout=10, text=True)
        if raw.returncode == 0:
            for line in raw.stdout.splitlines():
                value = json.loads(line)
                result["containers"].append({key: value.get(key) for key in ("ID", "Names", "Image", "State", "Status")})
        else:result["errors"].append("容器状态读取失败")
    except (OSError, ValueError, subprocess.TimeoutExpired):result["errors"].append("容器状态不可用")
    try:
        raw = subprocess.run(["/usr/bin/tmux", "list-sessions", "-F", "#{session_id}\t#{session_name}"], capture_output=True, timeout=5, text=True)
        if raw.returncode == 0:
            result["tmux_sessions"] = [dict(zip(("id", "name"), line.split("\t", 1))) for line in raw.stdout.splitlines() if "\t" in line]
    except (OSError, subprocess.TimeoutExpired):result["errors"].append("tmux 状态不可用")
    return result


def differences(before, after):
    old = {v["ID"]: v for v in before["containers"]}
    new = {v["ID"]: v for v in after["containers"]}
    sessions = {v["id"] for v in before["tmux_sessions"]}
    return {"created_containers": [v for k, v in new.items() if k not in old],
            "removed_containers": [v for k, v in old.items() if k not in new],
            "changed_containers": [v for k, v in new.items() if k in old and v["State"] != old[k]["State"]],
            "new_tmux_sessions": [v for v in after["tmux_sessions"] if v["id"] not in sessions],
            "note": "共享宿主前后快照差异不等于资源归属证明；不会自动删除这些容器或会话。"}