using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using MoShiro.Backend.Application;
using MoShiro.Protocol;

namespace MoShiro.Backend.Api;

/// <summary>运维端点：<c>/healthz</c>、<c>/metrics</c>（admin 令牌）、一行安装脚本（<c>/install</c>、<c>/install.ps1</c>）。</summary>
public static class OpsEndpoints
{
    private const string Tag = "ops";

    public static void Map(IEndpointRouteBuilder app)
    {
        app.MapGet("/healthz", HealthAsync)
            .Api("health_get", "SQLite and the raw data directory are both writable", Tag)
            .Returns<HealthDto>().ProducesProblems(503);
        app.MapGet("/metrics", MetricsAsync)
            .Api("metrics_get", "Prometheus metrics (requires ops.metrics)", Tag)
            .Produces(StatusCodes.Status200OK, contentType: "text/plain").ProducesProblems(401, 403);
        // 一行安装：面板给的命令先下载这份静态脚本、核对 SHA-256，再用环境变量里的面板地址、角色和一次性代码执行。
        // 脚本不含任何一次性的值，所以不需要代码，也可以直接拿去和发布页公布的哈希核对。
        app.MapGet("/install", (HttpContext http) => Static(http, InstallScripts.Sh, "text/x-shellscript"))
            .Api("install_sh", "The static one-line installer for Linux and macOS nodes (same bytes for everyone; its SHA-256 is published with each release)", Tag)
            .Produces(StatusCodes.Status200OK, contentType: "text/x-shellscript");
        app.MapGet("/install.sh", (HttpContext http) => Static(http, InstallScripts.Sh, "text/x-shellscript"))
            .ExcludeFromDescription();
        // 脚本要装的版本：CI 签名的发布清单（原样的字节）和签名。脚本用内置的发布公钥验签，再按清单里的 digest 拉镜像。
        app.MapGet("/install/manifest", (HttpContext http, JoinTokenService tokens, ReleaseService releases, BackendOptions options, string? code) => ManifestAsync(http, tokens, releases, options, code, signature: false))
            .Api("install_manifest", "The signed release manifest of the component an install code is for (exact signed bytes)", Tag)
            .Produces(StatusCodes.Status200OK, contentType: "application/json").ProducesProblems(404);
        app.MapGet("/install/manifest.sig", (HttpContext http, JoinTokenService tokens, ReleaseService releases, BackendOptions options, string? code) => ManifestAsync(http, tokens, releases, options, code, signature: true))
            .Api("install_manifest_signature", "Base64 DER ECDSA P-256 signature of the manifest", Tag)
            .Produces(StatusCodes.Status200OK, contentType: "text/plain").ProducesProblems(404);
        app.MapGet("/install.ps1", (HttpContext http) => Static(http, InstallScripts.Ps1, "text/plain"))
            .Api("install_ps1", "The static one-line installer for Windows nodes (same bytes for everyone; its SHA-256 is published with each release)", Tag)
            .Produces(StatusCodes.Status200OK, contentType: "text/plain");
    }

    private static async Task<IResult> ManifestAsync(HttpContext http, JoinTokenService tokens, ReleaseService releases, BackendOptions options, string? code, bool signature)
    {
        string baseUrl = options.PublicUrl ?? $"{http.Request.Scheme}://{http.Request.Host}";
        InstallTarget? target = string.IsNullOrEmpty(code) ? null : await tokens.ResolveInstallAsync(code, baseUrl, http.RequestAborted);
        ReleaseOffer? offer = target is null ? null : await releases.GetAsync(target.Role, http.RequestAborted);
        if (offer is null)
        {
            return Problems.Create(http, MoShiroErrors.NotFound, "no signed release is registered for this install code");
        }

        http.Response.Headers.CacheControl = "no-store";
        return signature ? TypedResults.Text(offer.Signature, "text/plain; charset=utf-8") : TypedResults.Text(offer.Manifest, "application/json; charset=utf-8");
    }

    private static Microsoft.AspNetCore.Http.HttpResults.ContentHttpResult Static(HttpContext http, string resource, string contentType)
    {
        http.Response.Headers.CacheControl = "no-store";
        return TypedResults.Text(InstallScripts.Script(resource), contentType + "; charset=utf-8");
    }

    private static async Task<IResult> HealthAsync(HttpContext http, OpsService ops)
    {
        StorageHealth health = await ops.HealthAsync(http.RequestAborted);
        bool ok = health.Database && health.RawDirectory;
        HealthDto dto = new(ok ? "ok" : "unavailable", health.Database, health.RawDirectory);
        http.Response.Headers.CacheControl = "no-store";
        return TypedResults.Json(dto, ApiJsonContext.Default.HealthDto, statusCode: ok ? StatusCodes.Status200OK : StatusCodes.Status503ServiceUnavailable);
    }

    private static async Task<IResult> MetricsAsync(HttpContext http, OpsService ops)
    {
        Principal principal = http.GetPrincipal();
        if (!principal.Has(Capability.OpsMetrics))
        {
            return principal.Kind != PrincipalKind.Anonymous
                ? Problems.Create(http, MoShiroErrors.Forbidden, "the ops.metrics capability is required")
                : Problems.Create(http, MoShiroErrors.Unauthorized, "authentication is required");
        }

        return TypedResults.Text(await ops.RenderPrometheusAsync(http.RequestAborted), "text/plain; version=0.0.4");
    }
}