using System.Diagnostics;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace ControlPlane.Api.Endpoints;

public static class InfraEndpoints
{
    public static IEndpointRouteBuilder MapInfraEndpoints(this IEndpointRouteBuilder app)
    {
        var g = app.MapGroup("/api/infra").WithTags("Infrastructure");

        g.MapGet ("/status",             GetStatus);
        g.MapPost("/{container}/start",  (string container) => ServiceAction(container, "start"));
        g.MapPost("/{container}/stop",   (string container) => ServiceAction(container, "stop"));
        g.MapPost("/{container}/restart",(string container) => ServiceAction(container, "restart"));
        g.MapGet ("/compose/up/stream",       ComposeUpStream);
        g.MapGet ("/compose/up-force/stream", ComposeUpForceStream);
        g.MapGet ("/compose/down/stream",     ComposeDownStream);

        return app;
    }

    // ── Known platform services ───────────────────────────────────────────────

    private static readonly string[] PlatformContainers =
    [
        "clarity-postgres",
        "clarity-keycloak",
        "clarity-vault",
        "clarity-minio",
        "clarity-gitea",
        "clarity-nginx",
        "clarity-dnsmasq",
    ];

    // ── Handlers ─────────────────────────────────────────────────────────────

    private static async Task<IResult> GetStatus()
    {
        var services = new List<InfraService>();

        foreach (var container in PlatformContainers)
        {
            var (code, output) = await DockerAsync(
                $"inspect --format={{{{json .}}}} {container}");

            if (code != 0 || string.IsNullOrWhiteSpace(output))
            {
                services.Add(new InfraService(container, container, "stopped", [], null));
                continue;
            }

            try
            {
                using var doc = JsonDocument.Parse(output.Trim());
                var root   = doc.RootElement;
                var state  = root.GetProperty("State").GetProperty("Status").GetString() ?? "unknown";
                var health = root.GetProperty("State").TryGetProperty("Health", out var h)
                    ? h.GetProperty("Status").GetString()
                    : null;

                var status = (state, health) switch
                {
                    ("running", "unhealthy") => "unhealthy",
                    ("running", _)           => "running",
                    ("exited",  _)           => "stopped",
                    _                        => state
                };

                // Ports
                var ports = new List<string>();
                if (root.TryGetProperty("NetworkSettings", out var ns) &&
                    ns.TryGetProperty("Ports", out var portsEl))
                {
                    foreach (var port in portsEl.EnumerateObject())
                    {
                        if (port.Value.ValueKind != JsonValueKind.Null)
                            ports.Add(port.Name.Split('/')[0]);
                    }
                }

                // Uptime
                string? uptime = null;
                if (root.GetProperty("State").TryGetProperty("StartedAt", out var startedAt))
                {
                    if (DateTime.TryParse(startedAt.GetString(), out var started) && state == "running")
                    {
                        var elapsed = DateTime.UtcNow - started.ToUniversalTime();
                        uptime = elapsed.TotalDays >= 1
                            ? $"{(int)elapsed.TotalDays}d {elapsed.Hours}h"
                            : elapsed.TotalHours >= 1
                                ? $"{(int)elapsed.TotalHours}h {elapsed.Minutes}m"
                                : $"{elapsed.Minutes}m";
                    }
                }

                // Friendly name
                var name = root.TryGetProperty("Name", out var n)
                    ? n.GetString()?.TrimStart('/') ?? container
                    : container;

                services.Add(new InfraService(name, container, status, ports, uptime));
            }
            catch
            {
                services.Add(new InfraService(container, container, "unknown", [], null));
            }
        }

        return Results.Ok(new InfraStatusResponse(services, DateTimeOffset.UtcNow));
    }

    private static async Task<IResult> ServiceAction(string container, string action)
    {
        if (!PlatformContainers.Contains(container))
            return Results.BadRequest($"Unknown platform container: {container}");

        var (code, output) = await DockerAsync($"{action} {container}");
        return code == 0
            ? Results.Ok()
            : Results.Problem(output ?? "Docker command failed", statusCode: 500);
    }

    // Starts all platform services; --remove-orphans cleans up containers with stale names
    // (e.g. a leftover clarity-dnsmasq that causes the "name already in use" conflict).
    private static Task ComposeUpStream(HttpContext ctx, IConfiguration config, CancellationToken ct) =>
        StreamComposeOutput(ctx, config, "up -d --remove-orphans", ct);

    // Force-recreates every container regardless of config drift — use after image or compose changes.
    private static Task ComposeUpForceStream(HttpContext ctx, IConfiguration config, CancellationToken ct) =>
        StreamComposeOutput(ctx, config, "up -d --force-recreate --remove-orphans", ct);

    private static Task ComposeDownStream(HttpContext ctx, IConfiguration config, CancellationToken ct) =>
        StreamComposeOutput(ctx, config, "down", ct);

    private static async Task StreamComposeOutput(
        HttpContext ctx, IConfiguration config, string composeArgs, CancellationToken ct)
    {
        var infraDir = ResolveInfraPath(config);

        ctx.Response.Headers.ContentType  = "text/event-stream";
        ctx.Response.Headers.CacheControl = "no-cache";
        ctx.Response.Headers.Connection   = "keep-alive";

        var channel = System.Threading.Channels.Channel.CreateUnbounded<string?>(
            new System.Threading.Channels.UnboundedChannelOptions { SingleWriter = false, SingleReader = true });

        var psi = new ProcessStartInfo("docker",
            $"compose -f \"{Path.Combine(infraDir, "docker-compose.yml")}\" {composeArgs}")
        {
            RedirectStandardOutput = true,
            RedirectStandardError  = true,
            UseShellExecute        = false,
            CreateNoWindow         = true,
            WorkingDirectory       = infraDir,
        };

        var proc = Process.Start(psi)!;

        // Read stdout + stderr concurrently into the channel
        var stdoutTask = Task.Run(async () =>
        {
            while (await proc.StandardOutput.ReadLineAsync(ct) is { } line)
                channel.Writer.TryWrite(line);
        }, ct);

        var stderrTask = Task.Run(async () =>
        {
            while (await proc.StandardError.ReadLineAsync(ct) is { } line)
                channel.Writer.TryWrite(line);
        }, ct);

        _ = Task.WhenAll(stdoutTask, stderrTask)
            .ContinueWith(_ => channel.Writer.TryComplete(), TaskScheduler.Default);

        // Stream lines to client as SSE
        await foreach (var line in channel.Reader.ReadAllAsync(ct))
        {
            if (line is null) continue;
            await ctx.Response.WriteAsync($"data: {line}\n\n", ct);
            await ctx.Response.Body.FlushAsync(ct);
        }

        await proc.WaitForExitAsync(ct);
        var exitLine = proc.ExitCode == 0 ? "data: ✔ Done." : $"data: ✖ Exited with code {proc.ExitCode}";
        await ctx.Response.WriteAsync($"{exitLine}\n\n", ct);
        await ctx.Response.Body.FlushAsync(ct);
        proc.Dispose();
    }

    // ── Helpers ───────────────────────────────────────────────────────────────

    private static string ResolveInfraPath(IConfiguration config)
    {
        var repoRoot = config["Docker:RepoRoot"]
            ?? Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..", "..", "..", ".."));
        return Path.GetFullPath(Path.Combine(repoRoot, "infra"));
    }

    private static Task<(int Code, string? Output)> DockerAsync(string args) =>
        RunAsync("docker", args, null);

    private static async Task<(int Code, string? Output)> ComposeAsync(string args, string infraDir)=>
        await RunAsync("docker", $"compose -f \"{Path.Combine(infraDir, "docker-compose.yml")}\" {args}", infraDir);

    private static async Task<(int Code, string? Output)> RunAsync(
        string exe, string args, string? workingDir)
    {
        var psi = new ProcessStartInfo(exe, args)
        {
            RedirectStandardOutput = true,
            RedirectStandardError  = true,
            UseShellExecute        = false,
            CreateNoWindow         = true,
        };
        if (workingDir is not null) psi.WorkingDirectory = workingDir;

        using var proc = Process.Start(psi);
        if (proc is null) return (-1, null);
        var output = await proc.StandardOutput.ReadToEndAsync();
        var err    = await proc.StandardError.ReadToEndAsync();
        await proc.WaitForExitAsync();
        return (proc.ExitCode, string.IsNullOrWhiteSpace(output) ? err : output);
    }

    // ── Response models ───────────────────────────────────────────────────────

    public record InfraService(
        string Name,
        string Container,
        string Status,
        List<string> Ports,
        string? Uptime);

    public record InfraStatusResponse(
        List<InfraService> Services,
        DateTimeOffset CheckedAt);
}