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）、安装脚本。</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 (admin token)", Tag)
            .Produces(StatusCodes.Status200OK, contentType: "text/plain").ProducesProblems(401, 403);
        app.MapGet("/install.sh", (HttpContext http) => NotShipped(http))
            .Api("install_sh", "Installer for Linux nodes", Tag).ProducesProblems(501);
        app.MapGet("/install.ps1", (HttpContext http) => NotShipped(http))
            .Api("install_ps1", "Installer for Windows nodes", Tag).ProducesProblems(501);
    }

    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.IsAdmin)
        {
            return principal.CanRead
                ? Problems.Create(http, MoShiroErrors.Forbidden, "an admin token is required")
                : Problems.Create(http, MoShiroErrors.Unauthorized, "an admin token is required");
        }

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

    /// <summary>安装脚本需要下载节点程序的发布物，那属于打包与部署（M6），目前还没有。</summary>
    private static IResult NotShipped(HttpContext http) =>
        Problems.Create(http, StatusCodes.Status501NotImplemented, ErrorCodeHttpMap.NotImplemented.Value, "the node installer ships with packaging (M6)");
}