package orchestrator

import (
	"context"
	"fmt"
	"log"
	"time"

	"vetting/internal/events"
	"vetting/internal/model"
	"vetting/internal/store"
)

// Runner is the authoritative mutator for run state. All state
// transitions go through (*Runner).Transition so the DB update and
// the event publication happen together.
type Runner struct {
	Runs     *store.Runs
	Hosts    *store.Hosts
	Stages   *store.Stages
	EventHub *events.Hub
}

func (r *Runner) Transition(ctx context.Context, runID int64, trigger Trigger) (model.RunState, error) {
	run, err := r.Runs.Get(ctx, runID)
	if err != nil {
		return "", fmt.Errorf("get run: %w", err)
	}
	next, err := Next(run.State, trigger)
	if err != nil {
		return "", err
	}
	if err := r.Runs.SetState(ctx, runID, next); err != nil {
		return "", fmt.Errorf("persist transition: %w", err)
	}
	log.Printf("run %d: %s -> %s (%s)", runID, run.State, next, trigger)
	r.publishTileUpdate(ctx, run.HostID)
	return next, nil
}

// StartStage marks a stage row running and publishes a tile refresh.
func (r *Runner) StartStage(ctx context.Context, runID int64, name string) error {
	if err := r.Stages.StartByName(ctx, runID, name); err != nil {
		return err
	}
	run, err := r.Runs.Get(ctx, runID)
	if err == nil {
		r.publishTileUpdate(ctx, run.HostID)
	}
	return nil
}

// CompleteStage marks a stage row passed/failed/skipped and publishes a
// tile + pipeline refresh. Wrapper around Stages.CompleteByName so every
// stage completion triggers an SSE update — without this, stage dots on
// the pipeline wouldn't advance until the next run-state transition.
func (r *Runner) CompleteStage(ctx context.Context, runID int64, name string, state model.StageState, summaryJSON string) error {
	if err := r.Stages.CompleteByName(ctx, runID, name, state, summaryJSON); err != nil {
		return err
	}
	run, err := r.Runs.Get(ctx, runID)
	if err == nil {
		r.publishTileUpdate(ctx, run.HostID)
	}
	return nil
}

// PublishTileUpdate is the exported entry point for non-orchestrator
// callers (the UI heartbeat handler) that change tile-visible state
// without going through Transition.
func (r *Runner) PublishTileUpdate(ctx context.Context, hostID int64) {
	r.publishTileUpdate(ctx, hostID)
}

// PublishHostDetail broadcasts fresh HTML fragments for every non-log,
// non-pipeline region of the host detail page: summary header, actions
// row, spec-diffs list, and the hold-key SSH block. Callers should
// invoke this alongside PublishTileUpdate from any site that mutates
// state visible on the detail page.
//
// Safe to call when no renderer has been registered or the host has
// been deleted; the call is silently dropped.
func (r *Runner) PublishHostDetail(ctx context.Context, hostID int64) {
	if HostDetailRenderer == nil || r.EventHub == nil {
		return
	}
	f, ok := HostDetailRenderer(ctx, hostID)
	if !ok {
		return
	}
	r.EventHub.Publish(events.Event{
		Name:    fmt.Sprintf("detail-summary-%d", hostID),
		Payload: f.Summary,
	})
	r.EventHub.Publish(events.Event{
		Name:    fmt.Sprintf("detail-actions-%d", hostID),
		Payload: f.Actions,
	})
	if f.LatestRunID != 0 {
		r.EventHub.Publish(events.Event{
			Name:    fmt.Sprintf("detail-specdiffs-%d", f.LatestRunID),
			Payload: f.SpecDiffs,
		})
		r.EventHub.Publish(events.Event{
			Name:    fmt.Sprintf("detail-hold-%d", f.LatestRunID),
			Payload: f.Hold,
		})
	}
}

func (r *Runner) publishTileUpdate(ctx context.Context, hostID int64) {
	host, err := r.Hosts.Get(ctx, hostID)
	if err != nil {
		log.Printf("publishTileUpdate: get host %d: %v", hostID, err)
		return
	}
	latest, err := r.Runs.LatestForHost(ctx, hostID)
	if err != nil {
		log.Printf("publishTileUpdate: latest run: %v", err)
		return
	}
	payload := renderTileSSE(ctx, *host, latest)
	r.EventHub.Publish(events.Event{Name: fmt.Sprintf("tile-%d", hostID), Payload: payload})

	// Pipeline fragment — same call sites as the tile refresh, keyed by
	// run ID so the detail page's <section sse-swap="pipeline-N"> picks
	// it up. Silently skips when no renderer is wired or no run exists.
	if latest != nil && PipelineRenderer != nil && r.Stages != nil {
		stages, err := r.Stages.ListForRun(ctx, latest.ID)
		if err != nil {
			log.Printf("publishTileUpdate: list stages run %d: %v", latest.ID, err)
		} else {
			pipePayload := PipelineRenderer(latest, stages)
			r.EventHub.Publish(events.Event{Name: fmt.Sprintf("pipeline-%d", latest.ID), Payload: pipePayload})
		}
	}

	// Detail-page fragments — everything on /hosts/{id} that isn't the
	// pipeline or the log pane. Co-located here so every site that
	// already publishes a tile refresh also refreshes the detail page
	// without the caller having to remember a second call.
	r.PublishHostDetail(ctx, hostID)
}

// TileRenderer renders a single tile fragment. Registered at startup
// so the orchestrator package stays free of template / store-enrichment
// imports. The closure is expected to do any DB lookups itself (spec-
// diff count, hold-key path, …) before handing the data to the
// template package.
var TileRenderer func(ctx context.Context, host model.Host, latest *model.Run) string

// PipelineRenderer renders the detail-page pipeline fragment for the
// given run + its stage rows. Registered alongside TileRenderer so
// orchestrator stays free of template imports.
var PipelineRenderer func(run *model.Run, stages []model.Stage) string

// SubStepRenderer renders a single sub-step row fragment. Fires on
// every sub-step state transition (running → passed/failed) so the
// detail page's `<div sse-swap="substep-{runID}-{stage}-{ordinal}">`
// target updates without reloading.
var SubStepRenderer func(ss model.SubStep) string

// PublishSubStepUpdate broadcasts a single sub-step row. Callers give
// the just-persisted SubStep; we render + fan out. Safe to call when
// no renderer is wired; drops silently.
func (r *Runner) PublishSubStepUpdate(ctx context.Context, ss model.SubStep) {
	if SubStepRenderer == nil || r.EventHub == nil {
		return
	}
	r.EventHub.Publish(events.Event{
		Name:    fmt.Sprintf("substep-%d-%s-%d", ss.RunID, ss.StageName, ss.Ordinal),
		Payload: SubStepRenderer(ss),
	})
}

// HostDetailFragments is the pre-rendered bundle of HTML fragments a
// single PublishHostDetail call broadcasts over SSE. Summary and Actions
// are always set; SpecDiffs and Hold are empty strings when there is no
// latest run (the corresponding events are not published in that case).
type HostDetailFragments struct {
	Summary     string
	Actions     string
	SpecDiffs   string
	Hold        string
	LatestRunID int64 // 0 when the host has no runs yet
}

// HostDetailRenderer produces the four fragments for a given host.
// Registered at startup by main so the orchestrator doesn't import the
// template or store-enrichment layers. Returns ok=false when the host
// cannot be loaded (deleted, DB error); caller skips publish in that
// case.
var HostDetailRenderer func(ctx context.Context, hostID int64) (HostDetailFragments, bool)

func renderTileSSE(ctx context.Context, host model.Host, latest *model.Run) string {
	if TileRenderer == nil {
		return fmt.Sprintf(`<article id="host-%d">state change</article>`, host.ID)
	}
	return TileRenderer(ctx, host, latest)
}

// TouchHeartbeat is called on every agent heartbeat so the orchestrator
// can record last-seen; Phase 2 just logs, Phase 3+ will update a
// last_seen_at column.
func (r *Runner) TouchHeartbeat(runID int64) {
	_ = runID
	_ = time.Now()
}

// Override re-enters a held stage after the operator has acknowledged
// the failure condition (e.g. wipe-probe override). It jumps
// FailedHolding → StateFor(failed_stage), clears the failed marker, and
// publishes a tile refresh so the UI drops the hold banner.
func (r *Runner) Override(ctx context.Context, runID int64, flagsJSON string) (model.RunState, error) {
	run, err := r.Runs.Get(ctx, runID)
	if err != nil {
		return "", fmt.Errorf("get run: %w", err)
	}
	if run.FailedStage == "" {
		return "", fmt.Errorf("override: run has no failed_stage")
	}
	next, err := NextForOverride(run.State, run.FailedStage)
	if err != nil {
		return "", err
	}
	if err := r.Runs.SetOverrideFlags(ctx, runID, flagsJSON); err != nil {
		return "", fmt.Errorf("persist override flags: %w", err)
	}
	if err := r.Runs.SetState(ctx, runID, next); err != nil {
		return "", fmt.Errorf("override transition: %w", err)
	}
	if err := r.Runs.ClearFailedStage(ctx, runID); err != nil {
		log.Printf("override: clear failed_stage: %v", err)
	}
	log.Printf("run %d: %s -> %s (OperatorOverride stage=%s flags=%s)", runID, run.State, next, run.FailedStage, flagsJSON)
	r.publishTileUpdate(ctx, run.HostID)
	return next, nil
}