package api

import (
	"context"
	"net/http"
)

// detailFillBatchSize bounds how many activities' details/splits are fetched
// per sync trigger, matching the sequential rate-limited fetch in
// internal/sync.Service.FillPendingDetails.
const detailFillBatchSize = 50

// handleSyncRun does a full sync pass: Backfill first (resumes from the
// watermark, so widening the configured history horizon between clicks is
// picked up automatically), then IncrementalSync (catches anything new since
// the latest known activity), then fills in details for whatever's still
// missing them. Activities already fully processed are left untouched --
// see internal/sync.Service.FillPendingDetails. Recorded as a single
// FullSync run so "last sync" reports the combined activity count, not just
// whichever of Backfill/IncrementalSync happened to finish last.
func (s *Server) handleSyncRun(w http.ResponseWriter, r *http.Request) {
	ok := s.backgroundSync(func(ctx context.Context) error {
		return s.Sync.FullSync(ctx, detailFillBatchSize)
	})
	if !ok {
		writeError(w, http.StatusConflict, "a sync is already in progress")
		return
	}
	writeJSON(w, http.StatusAccepted, map[string]string{"status": "started"})
}

// handleSyncReset wipes every synced activity (and its laps/samples/kind
// assignments) and rewinds the backfill watermark, so the next Sync Now
// performs a genuinely fresh pull from Garmin. Destructive -- the frontend
// gates this behind a confirmation.
func (s *Server) handleSyncReset(w http.ResponseWriter, r *http.Request) {
	ok := s.backgroundSync(func(ctx context.Context) error {
		return s.Sync.ResetAll(ctx)
	})
	if !ok {
		writeError(w, http.StatusConflict, "a sync is already in progress")
		return
	}
	writeJSON(w, http.StatusAccepted, map[string]string{"status": "started"})
}

func (s *Server) handleSyncRuns(w http.ResponseWriter, r *http.Request) {
	runs, err := s.DB.ListSyncRuns(r.Context(), 20)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, http.StatusOK, runs)
}

func (s *Server) handleSyncStatus(w http.ResponseWriter, r *http.Request) {
	run, ok, err := s.DB.LatestSyncRun(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	remaining, err := s.DB.CountActivitiesMissingDetails(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	s.mu.Lock()
	inProgress := s.syncRunning
	s.mu.Unlock()

	progress := s.Sync.Progress()

	resp := map[string]any{
		"in_progress":                inProgress,
		"detail_fill_progress":       progress,
		"activities_pending_details": remaining,
	}
	if ok {
		resp["last_run"] = run
	}
	writeJSON(w, http.StatusOK, resp)
}