using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;
using w4c_workflows.Models;
using w4c_workflows.Services;
using Xunit;

namespace w4c_workflows.Tests;

[Collection("WorkflowsPostgres")]
public class WorkflowSyncIntegrationTests
{
    private const string ExampleYaml = """
        name: main-task
        mode: handler
        language: typescript
        trigger:
          type: queue
          stream: orders
        entry: { file: index.ts, function: handler }
        tasks:
          - id: validate
            parent: root
            next: enrich
            onError: compensate
            language: python
            entry: { file: validate.py }
          - id: enrich
            parent: root
            next: persist
            language: csharp
            entry: { file: Enrich.cs }
          - id: persist
            parent: root
            language: shell
            entry: { file: persist.sh }
          - id: compensate
            parent: root
            language: python
            entry: { file: compensate.py }
        """;

    private readonly WorkflowsPostgresFixture _fixture;

    public WorkflowSyncIntegrationTests(WorkflowsPostgresFixture fixture)
    {
        _fixture = fixture;
    }

    private WorkflowSyncService NewSync(string tenantId, FakeWorkflowSource source)
    {
        var compiler = new WorkflowCompiler(new WorkflowValidator(new LanguageRegistry()));
        return new WorkflowSyncService(
            _fixture.CreateContext(), compiler, source, NullLogger<WorkflowSyncService>.Instance);
    }

    [Fact]
    public async Task Sync_compiles_and_persists_workflow_with_task_tree()
    {
        var tenantId = "t" + Guid.NewGuid().ToString("N")[..12];
        var source = new FakeWorkflowSource { ["workflows/main-task.yaml"] = ExampleYaml };

        var result = await NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);

        Assert.Equal(1, result.Compiled);
        Assert.Empty(result.Errors);

        await using var db = _fixture.CreateContext();
        var workflow = await db.Workflows.Include(w => w.Tasks).SingleAsync(w => w.TenantId == tenantId);
        Assert.Equal("main-task", workflow.Name);
        Assert.Equal("compiled", workflow.Status);
        Assert.Equal("abc123", workflow.GitSha);
        Assert.Equal(5, workflow.Tasks.Count);

        var root = workflow.Tasks.Single(t => t.Order == 0);
        var validate = workflow.Tasks.Single(t => t.Order == 1);
        Assert.Equal(validate.Id, root.NextId);
        Assert.NotNull(validate.OnErrorId);
    }

    [Fact]
    public async Task Sync_is_idempotent_across_repeat_syncs()
    {
        var tenantId = "t" + Guid.NewGuid().ToString("N")[..12];
        var source = new FakeWorkflowSource { ["workflows/main-task.yaml"] = ExampleYaml };
        var sync = () => NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);

        await sync();
        var second = await sync();

        Assert.Equal(1, second.Compiled);
        await using var db = _fixture.CreateContext();
        Assert.Equal(1, await db.Workflows.CountAsync(w => w.TenantId == tenantId));
        Assert.Equal(5, await db.Tasks.CountAsync(t => t.Workflow.TenantId == tenantId));
    }

    [Fact]
    public async Task Sync_reconciles_tasks_when_chain_changes()
    {
        var tenantId = "t" + Guid.NewGuid().ToString("N")[..12];
        var source = new FakeWorkflowSource
        {
            ["workflows/main-task.yaml"] = """
                name: main-task
                mode: function
                language: shell
                entry: { file: a.sh }
                tasks:
                  - id: a
                    next: b
                    entry: { file: a.sh }
                  - id: b
                    entry: { file: b.sh }
                """,
        };

        await NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);

        // Add a third task to the chain.
        source["workflows/main-task.yaml"] = """
            name: main-task
            mode: function
            language: shell
            entry: { file: a.sh }
            tasks:
              - id: a
                next: b
                entry: { file: a.sh }
              - id: b
                next: c
                entry: { file: b.sh }
              - id: c
                entry: { file: c.sh }
            """;

        await NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);

        await using var db = _fixture.CreateContext();
        var workflow = await db.Workflows.Include(w => w.Tasks).SingleAsync(w => w.TenantId == tenantId);
        Assert.Equal(4, workflow.Tasks.Count); // root + a + b + c
        Assert.Contains(workflow.Tasks, t => t.Order == 3);
    }

    [Fact]
    public async Task Sync_removes_workflow_when_file_deleted()
    {
        var tenantId = "t" + Guid.NewGuid().ToString("N")[..12];
        var source = new FakeWorkflowSource { ["workflows/main-task.yaml"] = ExampleYaml };

        await NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);
        source.Clear();

        var result = await NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);

        Assert.Equal(1, result.Removed);
        await using var db = _fixture.CreateContext();
        Assert.Equal(0, await db.Workflows.CountAsync(w => w.TenantId == tenantId));
    }

    [Fact]
    public async Task Sync_removing_a_task_archives_it_and_preserves_its_taskruns()
    {
        var tenantId = "t" + Guid.NewGuid().ToString("N")[..12];
        var source = new FakeWorkflowSource { ["workflows/main-task.yaml"] = ExampleYaml };

        await NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);

        // Give the 'enrich' task a historical run before it is removed from the YAML.
        Guid enrichId;
        await using (var db = _fixture.CreateContext())
        {
            var workflow = await db.Workflows.Include(w => w.Tasks).SingleAsync(w => w.TenantId == tenantId);
            var enrich = workflow.Tasks.Single(t => t.Order == 2); // 'enrich' (csharp)
            enrichId = enrich.Id;
            var run = new WorkflowRun
            {
                Id = Guid.NewGuid(),
                WorkflowId = workflow.Id,
                TenantId = tenantId,
                Status = RunStatus.Succeeded,
            };
            db.WorkflowRuns.Add(run);
            await db.SaveChangesAsync();
            db.TaskRuns.Add(new TaskRun
            {
                Id = Guid.NewGuid(),
                RunId = run.Id,
                TaskId = enrichId,
                Attempt = 1,
                Status = TaskRunStatus.Succeeded,
            });
            await db.SaveChangesAsync();
        }

        // Remove 'enrich' from the YAML (simulates a rename/removal of the task).
        source["workflows/main-task.yaml"] = """
            name: main-task
            mode: handler
            language: typescript
            trigger:
              type: queue
              stream: orders
            entry: { file: index.ts, function: handler }
            tasks:
              - id: validate
                parent: root
                next: persist
                onError: compensate
                language: python
                entry: { file: validate.py }
              - id: persist
                parent: root
                language: shell
                entry: { file: persist.sh }
              - id: compensate
                parent: root
                language: python
                entry: { file: compensate.py }
            """;

        await NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);

        await using var after = _fixture.CreateContext();
        // The historical TaskRun survives — sync no longer wipes it.
        Assert.Equal(1, await after.TaskRuns.CountAsync(t => t.TaskId == enrichId));
        // The removed task row is archived (soft-deleted), not deleted, and excluded
        // from active-definition queries.
        var archived = await after.Tasks.IgnoreQueryFilters().SingleAsync(t => t.Id == enrichId);
        Assert.NotNull(archived.ArchivedAt);
        Assert.False(await after.Tasks.AnyAsync(t => t.Id == enrichId));
    }

    [Fact]
    public async Task Sync_reports_errors_and_skips_invalid_files()
    {
        var tenantId = "t" + Guid.NewGuid().ToString("N")[..12];
        var source = new FakeWorkflowSource
        {
            ["workflows/broken.yaml"] = "name: broken\nmode: function\nlanguage: cobol\nentry: { file: x.sh }",
        };

        var result = await NewSync(tenantId, source).SyncAsync(tenantId, "workflows", default);

        Assert.Equal(0, result.Compiled);
        Assert.Single(result.Errors);
        Assert.Contains("not supported", result.Errors[0].Errors.Single());

        await using var db = _fixture.CreateContext();
        Assert.Equal(0, await db.Workflows.CountAsync(w => w.TenantId == tenantId));
    }

    private sealed class FakeWorkflowSource : IWorkflowSource
    {
        private readonly Dictionary<string, string> _files = new(StringComparer.Ordinal);

        public string this[string path]
        {
            get => _files[path];
            set => _files[path] = value;
        }

        public void Clear() => _files.Clear();

        public Task<IReadOnlyList<WorkflowFile>> ListAsync(CancellationToken ct)
            => Task.FromResult<IReadOnlyList<WorkflowFile>>(
                _files.Keys.Select(p => new WorkflowFile(p)).OrderBy(p => p.Path, StringComparer.Ordinal).ToList());

        public Task<string> ReadAsync(string path, CancellationToken ct)
            => Task.FromResult(_files[path]);

        public WorkflowSourceState GetState() => new("abc123", false);
    }
}