using System.Security.Cryptography;
using System.Text;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Transport;
using ZB.MOM.WW.ScadaBridge.Transport.Serialization;

namespace ZB.MOM.WW.ScadaBridge.Transport.Tests.Serialization;

public sealed class ManifestBuilderTests
{
    private static BundleSummary EmptySummary => new(0, 0, 0, 0, 0, 0, 0, 0);
    private static IReadOnlyList<ManifestContentEntry> NoContents => Array.Empty<ManifestContentEntry>();

    /// <summary>Verifies that building a manifest populates the summary from the contents.</summary>
    [Fact]
    public void Build_populates_summary_from_contents()
    {
        var sut = new ManifestBuilder();
        // Summary now carries trailing Sites/DataConnections/Instances counts.
        var summary = new BundleSummary(2, 1, 0, 0, 0, 0, 0, 0, Sites: 3, DataConnections: 4, Instances: 5);
        var contents = new[]
        {
            new ManifestContentEntry("Template", "T1", 1, Array.Empty<string>()),
            new ManifestContentEntry("Template", "T2", 1, new[] { "T1" }),
            new ManifestContentEntry("TemplateFolder", "F1", 1, Array.Empty<string>()),
        };

        var manifest = sut.Build("env", "user", "1.0.0", encryption: null, summary, contents, contentBytes: new byte[] { 1, 2, 3 });

        Assert.Equal(summary, manifest.Summary);
        // New summary counts flow through the builder verbatim.
        Assert.Equal(3, manifest.Summary.Sites);
        Assert.Equal(4, manifest.Summary.DataConnections);
        Assert.Equal(5, manifest.Summary.Instances);
        Assert.Equal(contents, manifest.Contents);
        Assert.Equal("env", manifest.SourceEnvironment);
        Assert.Equal("user", manifest.ExportedBy);
        Assert.Equal("1.0.0", manifest.ScadaBridgeVersion);
        Assert.Equal(1, manifest.BundleFormatVersion);
        // Schema minor bumped 1.0 → 1.1; format version stays 1.
        Assert.Equal("1.1", manifest.SchemaVersion);
        Assert.Null(manifest.Encryption);
    }

    /// <summary>Verifies that building a manifest computes a content hash with the sha256 prefix.</summary>
    [Fact]
    public void Build_computes_content_hash_with_sha256_prefix()
    {
        var sut = new ManifestBuilder();
        var bytes = Encoding.UTF8.GetBytes("known-content");
        var expectedHashHex = Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();

        var manifest = sut.Build("env", "user", "v", encryption: null, EmptySummary, NoContents, bytes);

        Assert.Equal("sha256:" + expectedHashHex, manifest.ContentHash);
    }

    /// <summary>Verifies that validation rejects an unsupported bundle format version.</summary>
    [Fact]
    public void Validate_rejects_unsupported_bundleFormatVersion()
    {
        var bytes = new byte[] { 1, 2, 3 };
        var hash = "sha256:" + Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();
        var manifest = new BundleManifest(
            BundleFormatVersion: 999,
            SchemaVersion: "1.0",
            CreatedAtUtc: DateTimeOffset.UtcNow,
            SourceEnvironment: "env",
            ExportedBy: "u",
            ScadaBridgeVersion: "v",
            ContentHash: hash,
            Encryption: null,
            Summary: EmptySummary,
            Contents: NoContents);

        var result = new ManifestValidator().Validate(manifest, bytes);

        Assert.Equal(ManifestValidationResult.UnsupportedFormatVersion, result);
    }

    /// <summary>Verifies that validation rejects a manifest whose content hash does not match.</summary>
    [Fact]
    public void Validate_rejects_when_contentHash_mismatch()
    {
        var bytes = new byte[] { 1, 2, 3 };
        var manifest = new BundleManifest(
            BundleFormatVersion: 1,
            SchemaVersion: "1.0",
            CreatedAtUtc: DateTimeOffset.UtcNow,
            SourceEnvironment: "env",
            ExportedBy: "u",
            ScadaBridgeVersion: "v",
            ContentHash: "sha256:deadbeef",
            Encryption: null,
            Summary: EmptySummary,
            Contents: NoContents);

        var result = new ManifestValidator().Validate(manifest, bytes);

        Assert.Equal(ManifestValidationResult.ContentHashMismatch, result);
    }

    /// <summary>Verifies that validation accepts a well-formed version 1 manifest.</summary>
    [Fact]
    public void Validate_accepts_well_formed_v1_manifest()
    {
        var sut = new ManifestBuilder();
        var bytes = Encoding.UTF8.GetBytes("hello");
        var manifest = sut.Build("env", "u", "v", encryption: null, EmptySummary, NoContents, bytes);

        var result = new ManifestValidator().Validate(manifest, bytes);

        Assert.Equal(ManifestValidationResult.Ok, result);
    }

    /// <summary>Verifies that validation accepts an older schema version 1.0 manifest.</summary>
    [Fact]
    public void Validate_accepts_older_schemaVersion_1_0_manifest()
    {
        // An older "1.0" bundle must still import: schema minor differences
        // are additive and the validator gates only on BundleFormatVersion.
        var bytes = Encoding.UTF8.GetBytes("legacy-bundle");
        var hash = "sha256:" + Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();
        var manifest = new BundleManifest(
            BundleFormatVersion: ManifestBuilder.CurrentBundleFormatVersion,
            SchemaVersion: "1.0",
            CreatedAtUtc: DateTimeOffset.UtcNow,
            SourceEnvironment: "env",
            ExportedBy: "u",
            ScadaBridgeVersion: "v",
            ContentHash: hash,
            Encryption: null,
            Summary: EmptySummary,
            Contents: NoContents);

        var result = new ManifestValidator().Validate(manifest, bytes);

        Assert.Equal(ManifestValidationResult.Ok, result);
    }

    /// <summary>Verifies that validation refuses bundle format version 2.</summary>
    [Fact]
    public void Validate_refuses_bundleFormatVersion_2()
    {
        // A future format-version 2 is a hard refusal (not a minor schema bump).
        var bytes = Encoding.UTF8.GetBytes("future-bundle");
        var hash = "sha256:" + Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();
        var manifest = new BundleManifest(
            BundleFormatVersion: 2,
            SchemaVersion: "1.1",
            CreatedAtUtc: DateTimeOffset.UtcNow,
            SourceEnvironment: "env",
            ExportedBy: "u",
            ScadaBridgeVersion: "v",
            ContentHash: hash,
            Encryption: null,
            Summary: EmptySummary,
            Contents: NoContents);

        var result = new ManifestValidator().Validate(manifest, bytes);

        Assert.Equal(ManifestValidationResult.UnsupportedFormatVersion, result);
    }
}