using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.FileProviders;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.Configuration;
using ZB.MOM.WW.Secrets.Configuration;
using ZB.MOM.WW.Secrets.DependencyInjection;
using ZB.MOM.WW.Secrets.Sqlite;

namespace ZB.MOM.WW.Secrets.Tests.Configuration;

/// <summary>
/// Covers the two store-path rules and the validator that applies them. Both rules exist because
/// of production incidents — a relative path landing in the process working directory, and an
/// absolute path landing inside the directory a deployment renames away — so the cases here are
/// written as those failures, not as abstract path arithmetic.
/// </summary>
public sealed class SecretsStorePathRulesTests
{
    private static string Root(params string[] segments) =>
        Path.Combine(OperatingSystem.IsWindows() ? @"C:\zbtest" : "/zbtest", Path.Combine(segments));

    // ---------- AddIfNotRooted ----------

    [Fact]
    public void NotRooted_rejects_a_relative_path()
    {
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfNotRooted("secrets.db", "relative", builder);
        Assert.Contains("relative", builder.Failures);
    }

    [Fact]
    public void NotRooted_accepts_an_absolute_path()
    {
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfNotRooted(Root("data", "secrets.db"), "relative", builder);
        Assert.True(builder.IsValid);
    }

    [Theory]
    [InlineData(null)]
    [InlineData("")]
    [InlineData("   ")]
    public void NotRooted_leaves_blank_to_the_required_check(string? value)
    {
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfNotRooted(value, "relative", builder);
        Assert.True(builder.IsValid);
    }

    // ---------- AddIfUnderContentRoot ----------

    [Fact]
    public void UnderContentRoot_rejects_a_store_inside_the_application_directory()
    {
        // The 2026-08-09 shape: absolute, and inside the directory the deploy renames away.
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfUnderContentRoot(
            Root("app", "Server", "secrets.db"), Root("app", "Server"), "inside", builder);
        Assert.Contains("inside", builder.Failures);
    }

    [Fact]
    public void UnderContentRoot_accepts_a_sibling_directory()
    {
        // The fix that was actually applied on the box: a sibling data\ directory.
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfUnderContentRoot(
            Root("app", "data", "secrets.db"), Root("app", "Server"), "inside", builder);
        Assert.True(builder.IsValid);
    }

    [Fact]
    public void UnderContentRoot_does_not_treat_a_name_prefixed_sibling_as_inside()
    {
        // "/zbtest/app-data" merely STARTS WITH "/zbtest/app". Without a separator before the
        // prefix test this is reported as inside the content root, and because the rule is
        // fail-closed at startup that false positive is an application that will not boot.
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfUnderContentRoot(
            Root("app-data", "secrets.db"), Root("app"), "inside", builder);
        Assert.True(builder.IsValid);
    }

    [Fact]
    public void UnderContentRoot_catches_a_path_that_only_escapes_syntactically()
    {
        // Normalisation matters: this resolves back inside the content root despite the "..".
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfUnderContentRoot(
            Path.Combine(Root("app", "Server"), "..", "Server", "secrets.db"),
            Root("app", "Server"),
            "inside",
            builder);
        Assert.Contains("inside", builder.Failures);
    }

    [Fact]
    public void UnderContentRoot_skips_when_the_content_root_is_unknown()
    {
        // Composed outside a host (the CLI does this). A rule about a directory the process does
        // not know it has must not become a boot failure.
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfUnderContentRoot(Root("anywhere", "secrets.db"), null, "inside", builder);
        Assert.True(builder.IsValid);
    }

    // ---------- the default ----------

    [Fact]
    public void The_default_store_path_satisfies_the_rules_it_ships_with()
    {
        // A library whose own default violates its own guard would fail every consumer's first
        // boot after upgrading.
        var builder = new ValidationBuilder();
        SecretsStorePathRules.AddIfNotRooted(SecretsOptions.DefaultSqlitePath, "relative", builder);
        Assert.True(builder.IsValid, $"default was '{SecretsOptions.DefaultSqlitePath}'");
    }

    [Fact]
    public void The_default_store_path_is_not_machine_wide()
    {
        // Deliberately per-user: CommonApplicationData is /usr/share on Linux and macOS, which a
        // normal user cannot write, so a machine-wide default would fail every dev boot in the
        // family. Asserted rather than commented because it is the whole reason for the choice.
        string commonAppData = Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData);
        if (!string.IsNullOrEmpty(commonAppData))
        {
            Assert.DoesNotContain(commonAppData, SecretsOptions.DefaultSqlitePath, StringComparison.Ordinal);
        }
    }

    // ---------- the validator ----------

    private static SecretsOptions OptionsWith(string path) => new() { SqlitePath = path };

    [Fact]
    public void Validator_rejects_a_relative_path_and_names_the_key()
    {
        var validator = new SecretsOptionsValidator(hostEnvironment: null);
        ValidateOptionsResult result = validator.Validate(name: null, OptionsWith("secrets.db"));

        Assert.True(result.Failed);
        Assert.Contains(result.Failures!, f => f.Contains("Secrets:SqlitePath", StringComparison.Ordinal));
    }

    [Fact]
    public void Validator_rejects_a_store_under_the_content_root()
    {
        var env = new StubHostEnvironment { ContentRootPath = Root("app", "Server") };
        var validator = new SecretsOptionsValidator(env);

        ValidateOptionsResult result =
            validator.Validate(name: null, OptionsWith(Root("app", "Server", "secrets.db")));

        Assert.True(result.Failed);
        Assert.Contains(result.Failures!, f => f.Contains("content root", StringComparison.Ordinal));
    }

    [Fact]
    public void Validator_accepts_an_absolute_path_outside_the_content_root()
    {
        var env = new StubHostEnvironment { ContentRootPath = Root("app", "Server") };
        var validator = new SecretsOptionsValidator(env);

        ValidateOptionsResult result =
            validator.Validate(name: null, OptionsWith(Root("app", "data", "secrets.db")));

        Assert.True(result.Succeeded);
    }

    // ---------- registration ----------

    [Fact]
    public void AddZbSecrets_is_idempotent_and_registers_exactly_one_validator()
    {
        // AddZbSecrets is called twice in real compositions — a replication package calls it after
        // the application already has, and one consumer calls it twice directly. An earlier
        // implementation used TryAddEnumerable with a factory descriptor, which THROWS on the
        // second call ("indistinguishable from other services") rather than skipping.
        IConfiguration config = new ConfigurationBuilder()
            .AddInMemoryCollection(new Dictionary<string, string?>
            {
                ["Secrets:SqlitePath"] = Root("app", "data", "secrets.db"),
            })
            .Build();

        var services = new ServiceCollection();
        services.AddZbSecrets(config, "Secrets");
        services.AddZbSecrets(config, "Secrets");

        Assert.Single(services.Where(d => d.ServiceType == typeof(SecretsOptionsValidator)));
        Assert.Single(services.Where(d => d.ServiceType == typeof(IValidateOptions<SecretsOptions>)));
    }

    [Fact]
    public void A_bad_path_actually_fails_when_the_options_are_resolved()
    {
        // The rules and the validator can both be correct while the REGISTRATION is wrong, and a
        // validator that is never invoked is precisely the "guard that does not fire" failure this
        // whole change exists to prevent. So resolve the options for real and require the throw.
        IConfiguration config = new ConfigurationBuilder()
            .AddInMemoryCollection(new Dictionary<string, string?>
            {
                ["Secrets:SqlitePath"] = "secrets.db",
            })
            .Build();

        var services = new ServiceCollection();
        services.AddZbSecrets(config, "Secrets");
        using ServiceProvider provider = services.BuildServiceProvider();

        var ex = Assert.Throws<OptionsValidationException>(
            () => _ = provider.GetRequiredService<IOptions<SecretsOptions>>().Value);
        Assert.Contains(ex.Failures, f => f.Contains("Secrets:SqlitePath", StringComparison.Ordinal));
    }

    [Fact]
    public void A_good_path_resolves_cleanly()
    {
        // Positive control: without it, the test above would still pass if EVERY path were rejected.
        IConfiguration config = new ConfigurationBuilder()
            .AddInMemoryCollection(new Dictionary<string, string?>
            {
                ["Secrets:SqlitePath"] = Root("app", "data", "secrets.db"),
            })
            .Build();

        var services = new ServiceCollection();
        services.AddZbSecrets(config, "Secrets");
        using ServiceProvider provider = services.BuildServiceProvider();

        Assert.Equal(
            Root("app", "data", "secrets.db"),
            provider.GetRequiredService<IOptions<SecretsOptions>>().Value.SqlitePath);
    }

    [Fact]
    public void A_pre_host_container_given_the_content_root_refuses_before_the_store_is_created()
    {
        // REGRESSION (found by the HistorianGateway adoption of 0.6.0). An application that expands
        // ${secret:} references before building its host composes this subsystem in a throwaway
        // ServiceCollection with NO IHostEnvironment, then migrates the store from that container.
        // The content-root rule was skipped there — so an absolute in-content-root path passed the
        // only rule still applying, the migrator CREATED the database, and the boot then failed a
        // second later once the real host registered IHostEnvironment. That left an empty store at
        // the rejected path: the exact artifact that made the outage this guard exists to prevent
        // read as "the database is there, it's just empty".
        string contentRoot = Path.Combine(Path.GetTempPath(), $"zb-prehost-{Guid.NewGuid():N}");
        Directory.CreateDirectory(contentRoot);
        string dbPath = Path.Combine(contentRoot, "store.db");

        try
        {
            IConfiguration config = new ConfigurationBuilder()
                .AddInMemoryCollection(new Dictionary<string, string?>
                {
                    ["Secrets:SqlitePath"] = dbPath,
                })
                .Build();

            var services = new ServiceCollection();
            services.AddZbSecrets(config, "Secrets", contentRoot);   // the content root, explicitly
            using ServiceProvider provider = services.BuildServiceProvider();

            Assert.Throws<OptionsValidationException>(
                () => _ = provider.GetRequiredService<SecretsSqliteConnectionFactory>());

            // The point of the test: refused BEFORE anything touched the filesystem.
            Assert.False(File.Exists(dbPath), "a rejected path must not be left holding a store file");
            Assert.False(File.Exists(dbPath + "-wal"));
            Assert.False(File.Exists(dbPath + "-shm"));
        }
        finally
        {
            Directory.Delete(contentRoot, recursive: true);
        }
    }

    [Fact]
    public void Without_a_content_root_the_pre_host_container_still_cannot_be_told_it_is_fine()
    {
        // Positive control for the test above: the SAME path, with the content root NOT supplied,
        // is the pre-0.6.1 behaviour — the rule is skipped and nothing objects. This is what makes
        // the assertion above about the explicit content root rather than about paths in general.
        string contentRoot = Path.Combine(Path.GetTempPath(), $"zb-prehost-{Guid.NewGuid():N}");
        Directory.CreateDirectory(contentRoot);
        string dbPath = Path.Combine(contentRoot, "store.db");

        try
        {
            IConfiguration config = new ConfigurationBuilder()
                .AddInMemoryCollection(new Dictionary<string, string?>
                {
                    ["Secrets:SqlitePath"] = dbPath,
                })
                .Build();

            var services = new ServiceCollection();
            services.AddZbSecrets(config, "Secrets");   // no content root — the CLI's situation
            using ServiceProvider provider = services.BuildServiceProvider();

            // Absolute, so the rooted rule passes; the content-root rule cannot fire. Documented,
            // and the reason pre-host composition must pass the content root explicitly.
            Assert.NotNull(provider.GetRequiredService<SecretsSqliteConnectionFactory>());
        }
        finally
        {
            Directory.Delete(contentRoot, recursive: true);
        }
    }

    private sealed class StubHostEnvironment : IHostEnvironment
    {
        public string EnvironmentName { get; set; } = "Production";
        public string ApplicationName { get; set; } = "Test";
        public string ContentRootPath { get; set; } = string.Empty;
        public IFileProvider ContentRootFileProvider { get; set; } = null!;
    }
}