using ControlPlane.Core.Interfaces;
using ControlPlane.Core.Models;
using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using System.Text.Json.Nodes;

namespace ControlPlane.Worker.Steps;

public class VaultStep(ILogger<VaultStep> logger, IConfiguration config) : ISagaStep
{
    public string StepName => "Cryptographic Pre-Flight (Vault)";

    // Policy grants the tenant token exactly the three Transit operations Clarity.Server needs:
    //   GenerateTenantKEKAsync  → datakey/plaintext  (first boot only)
    //   DecryptTenantKEKAsync   → decrypt            (every restart)
    //   RewrapTenantKEKAsync    → rewrap             (key rotation)
    private const string PolicyTemplate = """
        path "clarity-transit/datakey/plaintext/master-key" {
          capabilities = ["update"]
        }
        path "clarity-transit/decrypt/master-key" {
          capabilities = ["update"]
        }
        path "clarity-transit/rewrap/master-key" {
          capabilities = ["update"]
        }
        """;

    public async Task ExecuteAsync(SagaContext context, CancellationToken cancellationToken)
    {
        var rootToken = ReadRootToken();
        var vaultAddr = (config["Vault:Address"] ?? "http://localhost:8200").TrimEnd('/');
        var subdomain = context.Job.Subdomain.ToLowerInvariant();
        var policyName = $"clarity-tenant-{subdomain}";

        using var http = new HttpClient { BaseAddress = new Uri(vaultAddr) };
        http.DefaultRequestHeaders.Add("X-Vault-Token", rootToken);

        // ── 1. Assert Transit engine + master-key are healthy ─────────────────
        logger.LogInformation("[{JobId}] Verifying Vault Transit engine and master-key.", context.Job.Id);
        var healthRes = await http.GetAsync("v1/clarity-transit/keys/master-key", cancellationToken);
        if (!healthRes.IsSuccessStatusCode)
            throw new InvalidOperationException(
                $"Vault Transit master-key not found at {vaultAddr}. " +
                "Ensure OPC infra is running and the entrypoint has bootstrapped Vault.");

        // ── 2. Upsert per-tenant policy (idempotent PUT) ──────────────────────
        logger.LogInformation("[{JobId}] Writing Vault policy '{Policy}'.", context.Job.Id, policyName);
        var policyBody = JsonSerializer.Serialize(new { policy = PolicyTemplate });
        var policyRes = await http.PutAsync(
            $"v1/sys/policies/acl/{policyName}",
            new StringContent(policyBody, Encoding.UTF8, "application/json"),
            cancellationToken);
        policyRes.EnsureSuccessStatusCode();

        // ── 3. Create scoped periodic token bound to tenant policy ────────────
        logger.LogInformation("[{JobId}] Creating scoped Vault token for policy '{Policy}'.", context.Job.Id, policyName);
        var tokenBody = JsonSerializer.Serialize(new
        {
            policies  = new[] { policyName },
            period    = "72h",
            renewable = true,
            metadata  = new Dictionary<string, string>
            {
                ["tenant"]    = subdomain,
                ["createdBy"] = "ControlPlane.Worker",
            },
        });
        var tokenRes = await http.PostAsync(
            "v1/auth/token/create",
            new StringContent(tokenBody, Encoding.UTF8, "application/json"),
            cancellationToken);
        tokenRes.EnsureSuccessStatusCode();

        var tokenJson = JsonNode.Parse(await tokenRes.Content.ReadAsStringAsync(cancellationToken))!;
        context.VaultToken         = tokenJson["auth"]!["client_token"]!.GetValue<string>();
        context.VaultTokenAccessor = tokenJson["auth"]!["accessor"]!.GetValue<string>();

        logger.LogInformation("[{JobId}] Vault step complete. Token accessor: {Accessor}",
            context.Job.Id, context.VaultTokenAccessor);

        context.Job.CompletedSteps |= CompletedSteps.VaultVerified;
    }

    public async Task CompensateAsync(SagaContext context, CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(context.VaultTokenAccessor)) return;

        logger.LogWarning("[{JobId}] Compensating Vault — revoking token accessor {Accessor}.",
            context.Job.Id, context.VaultTokenAccessor);

        try
        {
            var rootToken = ReadRootToken();
            var vaultAddr = (config["Vault:Address"] ?? "http://localhost:8200").TrimEnd('/');
            using var http = new HttpClient { BaseAddress = new Uri(vaultAddr) };
            http.DefaultRequestHeaders.Add("X-Vault-Token", rootToken);

            var body = JsonSerializer.Serialize(new { accessor = context.VaultTokenAccessor });
            await http.PostAsync(
                "v1/auth/token/revoke-accessor",
                new StringContent(body, Encoding.UTF8, "application/json"),
                cancellationToken);
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "[{JobId}] Failed to revoke Vault token accessor {Accessor} during compensation.",
                context.Job.Id, context.VaultTokenAccessor);
        }
    }

    internal string ReadRootToken()
    {
        var path = config["Vault:KeysFile"] ?? config["Vault__KeysFile"];
        if (!string.IsNullOrWhiteSpace(path) && File.Exists(path))
        {
            using var doc = JsonDocument.Parse(File.ReadAllText(path));
            if (doc.RootElement.TryGetProperty("root_token", out var tok))
                return tok.GetString()!;
        }

        return config["Vault:Token"]
            ?? throw new InvalidOperationException(
                "Cannot resolve Vault root token: neither Vault:KeysFile nor Vault:Token is configured.");
    }
}