using System.Reflection;
using System.Security.Cryptography;
using System.Text;

namespace MoShiro.Backend.Api;

/// <summary>
/// 一行安装脚本：<c>packaging/install/</c> 下的 <c>install.sh</c> 和 <c>install.ps1</c> 作为嵌入资源打进 Backend，<b>原样返回，不替换任何值</b>。
/// 静态，所以它的 SHA-256 在一个版本内固定：CI 构建时算出来写进签名的发布清单，面板给的命令先核对哈希再执行（docs/security/access.md 第 10 节）。
/// 角色、面板地址、代码都走命令里的环境变量。
/// </summary>
public static class InstallScripts
{
    public const string Sh = "install.sh";
    public const string Ps1 = "install.ps1";

    /// <summary>CI 的发布公钥（<c>packaging/update/release-key.pub.pem</c>）：脚本里内置的就是这一把，测试核对两边一致。</summary>
    public static string ReleaseKey() => Read("release-key.pub.pem").Trim();

    public static string Script(string resource) => Read(resource);

    /// <summary>compose 文件的资源名（<c>agent.yaml</c>、<c>probe.yaml</c>、<c>backend.yaml</c> 对应的）；不是这三个就是 null。</summary>
    public static string? ComposeResource(string file) => file is "agent.yaml" or "probe.yaml" or "backend.yaml" ? "compose-" + file : null;

    /// <summary>某个角色（agent、probe）的 compose 文件的 SHA-256；其他角色返回空。</summary>
    public static string ComposeSha256(string? role) => role is "agent" or "probe" ? Sha256("compose-" + role + ".yaml") : string.Empty;

    /// <summary>Quadlet 单元的资源名（<c>agent.container</c>、<c>probe.container</c>）；不是这两个就是 null。</summary>
    public static string? QuadletResource(string file) => file is "agent.container" or "probe.container" ? "quadlet-" + file : null;

    /// <summary>某个角色（agent、probe）的 Quadlet 单元的 SHA-256；其他角色返回空。</summary>
    public static string QuadletSha256(string? role) => role is "agent" or "probe" ? Sha256("quadlet-" + role + ".container") : string.Empty;

    /// <summary>脚本内容的 SHA-256（小写十六进制，按 UTF-8 字节）。</summary>
    public static string Sha256(string resource) => Convert.ToHexStringLower(SHA256.HashData(Encoding.UTF8.GetBytes(Read(resource))));

    private static string Read(string resource)
    {
        using Stream stream = typeof(InstallScripts).Assembly.GetManifestResourceStream(resource)
            ?? throw new InvalidOperationException($"the embedded resource {resource} is missing");
        using var reader = new StreamReader(stream);
        return reader.ReadToEnd();
    }
}