using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using w4c_workflows.Data;
using w4c_workflows.Filters;
using w4c_workflows.Models;
using w4c_workflows.Services;
using w4c_workflows.Services.Runs;
using YamlDotNet.Serialization;
using YamlDotNet.Serialization.NamingConventions;

namespace w4c_workflows.Controllers;

/// <summary>
/// Workflow definitions + git sync. All endpoints authenticate with the
/// tenant's operator key (see AuthMiddleware).
/// </summary>
[ApiController]
[Route("api/workflows")]
public class WorkflowsController : ControllerBase
{
    private readonly WorkflowsDbContext _db;
    private readonly WorkflowSyncService _sync;
    private readonly IWorkflowSource _source;
    private readonly MermaidGeneratorService _mermaid;
    private readonly WorkflowHtmlRenderer _html;
    private readonly RenderTokenService _renderTokens;
    private readonly IRunLauncher _launcher;
    private readonly DurableStateStore _durable;
    private readonly IDeserializer _yaml;
    private readonly ILogger<WorkflowsController> _logger;

    public WorkflowsController(
        WorkflowsDbContext db,
        WorkflowSyncService sync,
        IWorkflowSource source,
        MermaidGeneratorService mermaid,
        WorkflowHtmlRenderer html,
        RenderTokenService renderTokens,
        IRunLauncher launcher,
        DurableStateStore durable,
        ILogger<WorkflowsController> logger)
    {
        _db = db;
        _sync = sync;
        _source = source;
        _mermaid = mermaid;
        _html = html;
        _renderTokens = renderTokens;
        _launcher = launcher;
        _durable = durable;
        _logger = logger;
        _yaml = new DeserializerBuilder()
            .WithNamingConvention(CamelCaseNamingConvention.Instance)
            .IgnoreUnmatchedProperties()
            .Build();
    }

    private string TenantId => (string?)HttpContext.Items["TenantId"]
        ?? throw new InvalidOperationException("TenantId not resolved by auth middleware");

    /// <summary>Lists compiled workflows with git sync status + latest run.</summary>
    [HttpGet]
    [RequireScope("read")]
    public async Task<IActionResult> List(CancellationToken ct)
    {
        var state = _source.GetState();
        var workflows = await _db.Workflows
            .Where(w => w.TenantId == TenantId)
            .OrderBy(w => w.Name)
            .Select(w => new
            {
                w.Id,
                w.Name,
                w.Path,
                w.GitSha,
                w.Status,
                w.Mode,
                w.Target,
                w.TriggerEnabled,
                w.TriggerJson,
                w.CompiledAt,
                w.UpdatedAt,
                w.Version,
                taskCount = w.Tasks.Count,
                upToDate = w.GitSha == state.HeadSha,
            })
            .ToListAsync(ct);

        // Latest run per workflow (status + finish time) so the list can surface
        // the last execution in one column without a round-trip per row.
        var ids = workflows.Select(w => w.Id).ToList();
        var lastRuns = await _db.WorkflowRuns
            .Where(r => r.TenantId == TenantId && ids.Contains(r.WorkflowId))
            .GroupBy(r => r.WorkflowId)
            .Select(g => new
            {
                WorkflowId = g.Key,
                Status = g
                    .OrderByDescending(r => r.StartedAt ?? r.FinishedAt ?? DateTime.MinValue)
                    .ThenByDescending(r => r.Id)
                    .Select(r => r.Status)
                    .FirstOrDefault(),
                StartedAt = g
                    .OrderByDescending(r => r.StartedAt ?? r.FinishedAt ?? DateTime.MinValue)
                    .ThenByDescending(r => r.Id)
                    .Select(r => r.StartedAt)
                    .FirstOrDefault(),
                FinishedAt = g
                    .OrderByDescending(r => r.StartedAt ?? r.FinishedAt ?? DateTime.MinValue)
                    .ThenByDescending(r => r.Id)
                    .Select(r => r.FinishedAt)
                    .FirstOrDefault(),
                Error = g
                    .OrderByDescending(r => r.StartedAt ?? r.FinishedAt ?? DateTime.MinValue)
                    .ThenByDescending(r => r.Id)
                    .Select(r => r.Error)
                    .FirstOrDefault(),
            })
            .ToDictionaryAsync(x => x.WorkflowId, ct);

        var result = workflows.Select(w =>
        {
            lastRuns.TryGetValue(w.Id, out var last);
            return new
            {
                w.Id,
                w.Name,
                w.Path,
                w.GitSha,
                w.Status,
                w.Mode,
                w.Target,
                w.TriggerEnabled,
                w.TriggerJson,
                w.CompiledAt,
                w.UpdatedAt,
                w.Version,
                w.taskCount,
                w.upToDate,
                lastRunStatus = last?.Status,
                lastRunAt = last?.FinishedAt ?? last?.StartedAt,
                lastRunError = last?.Error,
            };
        });

        return Ok(new { headSha = state.HeadSha, dirty = state.Dirty, workflows = result });
    }

    /// <summary>
    /// Returns the workflow definition, its compiled task tree, and the raw YAML
    /// source from git (for the Monaco task editor). The YAML is the
    /// authoritative source; edits are saved back via the Source Code API and
    /// recompiled with <c>POST /api/workflows/sync</c>.
    /// </summary>
    [HttpGet("{id:guid}")]
    [RequireScope("read")]
    public async Task<IActionResult> Get(Guid id, CancellationToken ct)
    {
        var workflow = await _db.Workflows
            .Include(w => w.Tasks)
            .FirstOrDefaultAsync(w => w.Id == id && w.TenantId == TenantId, ct);
        if (workflow == null)
            return NotFound(new { error = "Workflow not found." });

        string? yaml = null;
        try
        {
            yaml = await _source.ReadAsync(workflow.Path, ct);
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Failed to read workflow source {Path}", workflow.Path);
        }

        return Ok(new
        {
            workflow.Id,
            workflow.Name,
            workflow.Path,
            workflow.Mode,
            workflow.Target,
            workflow.Status,
            workflow.TriggerEnabled,
            workflow.TriggerJson,
            workflow.CompiledAt,
            workflow.UpdatedAt,
            workflow.GitSha,
            workflow.Version,
            yaml,
            tasks = workflow.Tasks
                .OrderBy(t => t.Order)
                .Select(t => new
                {
                    t.Id,
                    t.Key,
                    t.ParentId,
                    t.NextId,
                    t.OnErrorId,
                    t.Language,
                    t.Mode,
                    t.EntryJson,
                    t.EnvJson,
                    t.Order,
                }),
        });
    }

    /// <summary>Returns Mermaid source for a workflow diagram type.</summary>
    [HttpGet("{id:guid}/diagrams/{type}")]
    [RequireScope("read")]
    public async Task<IActionResult> Diagram(Guid id, string type, CancellationToken ct)
    {
        if (!MermaidGeneratorService.Types.Contains(type))
            return BadRequest(new { error = $"Unknown diagram type '{type}'. Expected one of {string.Join(", ", MermaidGeneratorService.Types)}." });

        var workflow = await _db.Workflows
            .Include(w => w.Tasks)
            .FirstOrDefaultAsync(w => w.Id == id && w.TenantId == TenantId, ct);
        if (workflow == null)
            return NotFound(new { error = "Workflow not found." });

        var source = _mermaid.Generate(type, workflow, workflow.Tasks);
        return Ok(new { type, source });
    }

    /// <summary>
    /// Mints a short-lived signed token that authorizes the iframe HTML preview
    /// (<c>GET /api/workflows/{id}/html?token=...</c>). Requires the operator key
    /// (default auth); an iframe cannot send that header, so the token is the
    /// drop-in replacement. The token binds tenant + workflow id and expires.
    /// </summary>
    [HttpGet("{id:guid}/html-token")]
    [RequireScope("read")]
    public async Task<IActionResult> GetHtmlToken(Guid id, CancellationToken ct)
    {
        var workflow = await _db.Workflows
            .FirstOrDefaultAsync(w => w.Id == id && w.TenantId == TenantId, ct);
        if (workflow == null)
            return NotFound(new { error = "Workflow not found." });

        var ttl = TimeSpan.FromHours(1);
        string token;
        try
        {
            token = _renderTokens.Issue(TenantId, id, ttl);
        }
        catch (InvalidOperationException)
        {
            return StatusCode(StatusCodes.Status503ServiceUnavailable, new
            {
                error = "Render token service is not configured (Auth:JwtSigningKey is missing).",
            });
        }
        return Ok(new { token, expiresAt = DateTimeOffset.UtcNow.Add(ttl) });
    }

    /// <summary>
    /// Renders a workflow as a self-contained, non-Mermaid HTML document (rich
    /// detail: success chain, compensation edges, full task inventory). Served as
    /// <c>text/html</c> so ANY client can embed it in an <c>&lt;iframe&gt;</c> —
    /// no client-side diagram library is needed. Auth: either the operator-key
    /// header (API use) or a signed <c>?token=</c> (iframe use).
    /// </summary>
    [HttpGet("{id:guid}/html")]
    [RequireScope("read")]
    public async Task<IActionResult> Html(Guid id, CancellationToken ct, string? theme = null)
    {
        // When the request came through a signed render token, make sure the
        // token is for this exact workflow (the middleware already proved the
        // signature + expiry and resolved the tenant).
        if (HttpContext.Items["AuthKind"] as string == "render-token")
        {
            var tokenWorkflow = HttpContext.Items["RenderWorkflowId"] as Guid?;
            if (tokenWorkflow != id)
                return StatusCode(StatusCodes.Status403Forbidden, new { error = "Render token does not match this workflow." });
        }

        var workflow = await _db.Workflows
            .Include(w => w.Tasks)
            .FirstOrDefaultAsync(w => w.Id == id && w.TenantId == TenantId, ct);
        if (workflow == null)
            return NotFound(new { error = "Workflow not found." });
        if (!string.Equals(workflow.Status, WorkflowStatus.Compiled, StringComparison.Ordinal))
            return BadRequest(new { error = $"Cannot render a '{workflow.Status}' workflow." });

        // Best-effort: read the YAML to enrich the header (description, workflow
        // env, entry). The compiled tasks are still the source of truth for the
        // graph/detail; a read/parse failure only degrades the header fields.
        WorkflowDefinition? def = null;
        try
        {
            var yaml = await _source.ReadAsync(workflow.Path, ct);
            def = _yaml.Deserialize<WorkflowDefinition>(yaml) ?? new WorkflowDefinition();
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Failed to read YAML for workflow {Path}; rendering header without description", workflow.Path);
        }

        var dark = string.Equals(theme, "dark", StringComparison.OrdinalIgnoreCase);
        var html = _html.Render(workflow, workflow.Tasks, def, dark);
        return Content(html, "text/html");
    }

    /// <summary>Re-reads workflows/*.yaml from git, compiles, and updates the DB.</summary>
    [HttpPost("sync")]
    [RequireScope("manage")]
    public async Task<IActionResult> Sync(CancellationToken ct)
    {
        var result = await _sync.SyncAsync(TenantId, ct);
        _logger.LogInformation(
            "Workflow sync for tenant {TenantId}: {Compiled} compiled, {Removed} removed, {Errors} errors",
            TenantId, result.Compiled, result.Removed, result.Errors.Count);

        return Ok(new
        {
            result.HeadSha,
            result.Dirty,
            result.Compiled,
            result.Removed,
            errors = result.Errors.Select(e => new { path = e.Path, messages = e.Errors }),
        });
    }

    public sealed record RunRequest(string? Input = null);

    /// <summary>
    /// Manual/event trigger: starts a run of a compiled workflow immediately.
    /// The run is created <c>pending</c>; the run lifecycle engine (step 9)
    /// dispatches and drives it. Returns 202 with the run id.
    /// </summary>
    [HttpPost("{id:guid}/run")]
    [RequireScope("run")]
    public async Task<IActionResult> Run(Guid id, [FromBody] RunRequest? request, CancellationToken ct)
    {
        try
        {
            var workflow = await _db.Workflows
                .FirstOrDefaultAsync(w =>
                    w.Id == id && w.TenantId == TenantId && w.Status == WorkflowStatus.Compiled, ct);
            if (workflow == null)
                return NotFound(new { error = "Workflow not found." });

            var triggerJson = System.Text.Json.JsonSerializer.Serialize(new { type = TriggerType.Event });
            var correlation = $"manual:{Guid.NewGuid():N}";
            var runId = await _launcher.LaunchAsync(
                new LaunchRequest(TenantId, id, triggerJson, request?.Input, correlation), ct);

            return Accepted(new { runId });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to start workflow run {WorkflowId} for tenant {TenantId}", id, TenantId);
            return StatusCode(StatusCodes.Status500InternalServerError, new { error = ex.Message });
        }
    }

    /// <summary>
    /// Enables or disables the workflow's auto-trigger (cron/interval/webhook/
    /// handler). Manual "run now" is unaffected. The trigger scheduler skips
    /// disabled workflows.
    ///
    /// NOTE: the route token is <c>{actionName}</c>, NOT <c>{action}</c> — MVC
    /// reserves <c>action</c> as a route value, so <c>{action}</c> in an
    /// attribute template makes the endpoint unreachable at runtime (404 on the
    /// very route OpenAPI advertises).
    /// </summary>
    [HttpPost("{id:guid}/trigger/{actionName}")]
    [RequireScope("manage")]
    public async Task<IActionResult> SetTriggerEnabled(Guid id, string actionName, CancellationToken ct)
    {
        if (actionName is not ("enable" or "disable"))
            return BadRequest(new { error = $"Unknown trigger action '{actionName}'. Expected 'enable' or 'disable'." });

        var workflow = await _db.Workflows
            .FirstOrDefaultAsync(w => w.Id == id && w.TenantId == TenantId, ct);
        if (workflow == null)
            return NotFound(new { error = "Workflow not found." });

        workflow.TriggerEnabled = actionName == "enable";
        await _db.SaveChangesAsync(ct);

        _logger.LogInformation("Trigger {Action}d for workflow {WorkflowId} (tenant {TenantId})",
            actionName, id, TenantId);
        return Ok(new TriggerStateResponse(id, workflow.TriggerEnabled));
    }

    public sealed record TriggerStateResponse(Guid Id, bool TriggerEnabled);

    public sealed record ResumeRequest(string? Input = null);

    /// <summary>
    /// Durable resume: continues a <c>durable</c>/<c>handler</c> instance from its
    /// last checkpoint (the checkpointed next task) with the supplied input
    /// (falling back to the checkpointed input). Creates a new run starting at
    /// <c>StartTaskId</c> so history shows each execution.
    /// </summary>
    [HttpPost("{id:guid}/instances/{instanceId}/resume")]
    [RequireScope("run")]
    public async Task<IActionResult> Resume(Guid id, string instanceId, [FromBody] ResumeRequest? request, CancellationToken ct)
    {
        try
        {
            var workflow = await _db.Workflows
                .Include(w => w.Tasks)
                .FirstOrDefaultAsync(w => w.Id == id && w.TenantId == TenantId && w.Status == WorkflowStatus.Compiled, ct);
            if (workflow == null)
                return NotFound(new { error = "Workflow not found." });

            var checkpoint = await _durable.GetAsync(instanceId, ct);
            if (checkpoint == null)
                return NotFound(new { error = $"No durable checkpoint for instance '{instanceId}'." });

            var resumeTask = workflow.Tasks.FirstOrDefault(t => t.Id == checkpoint.TaskId);
            if (resumeTask == null)
                return BadRequest(new { error = $"Checkpointed task '{checkpoint.TaskId}' does not belong to this workflow." });

            var input = request?.Input ?? checkpoint.StateJson;
            var correlation = $"resume:{instanceId}:{Guid.NewGuid():N}";
            var runId = await _launcher.LaunchAsync(
                new LaunchRequest(TenantId, id, workflow.TriggerJson, input, correlation, checkpoint.TaskId), ct);

            return Accepted(new { runId, resumedTaskId = checkpoint.TaskId });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to resume workflow {WorkflowId} instance {InstanceId} for tenant {TenantId}", id, instanceId, TenantId);
            return StatusCode(StatusCodes.Status500InternalServerError, new { error = ex.Message });
        }
    }
}