package handler

import (
	"encoding/json"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"
	"vctp/internal/report"
)

// SnapshotRegenerateHourlyReports regenerates missing hourly snapshot XLSX reports on disk.
// @Summary Regenerate hourly snapshot reports
// @Description Regenerates XLSX reports for hourly snapshots when the report files are missing or empty.
// @Tags snapshots
// @Produce json
// @Success 200 {object} map[string]interface{} "Regeneration summary"
// @Failure 500 {object} map[string]string "Server error"
// @Router /api/snapshots/regenerate-hourly-reports [post]
func (h *Handler) SnapshotRegenerateHourlyReports(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	reportsDir := strings.TrimSpace(h.Settings.Values.Settings.ReportsDir)
	if reportsDir == "" {
		reportsDir = "/var/lib/vctp/reports"
	}
	if err := os.MkdirAll(reportsDir, 0o755); err != nil {
		h.Logger.Error("failed to create reports directory", "error", err, "path", reportsDir)
		writeJSONError(w, http.StatusInternalServerError, "failed to create reports directory")
		return
	}

	start := time.Unix(0, 0)
	end := time.Now().AddDate(10, 0, 0) // sufficiently in the future to include all records
	records, err := report.SnapshotRecordsWithFallback(ctx, h.Database, "hourly", "inventory_hourly_", "epoch", start, end)
	if err != nil {
		h.Logger.Error("failed to list hourly snapshots", "error", err)
		writeJSONError(w, http.StatusInternalServerError, "failed to list hourly snapshots")
		return
	}

	var regenerated, skipped, errors int
	for _, rec := range records {
		dest := filepath.Join(reportsDir, rec.TableName+".xlsx")
		if info, err := os.Stat(dest); err == nil && info.Size() > 0 {
			skipped++
			continue
		}
		if _, err := report.SaveTableReport(h.Logger, h.Database, ctx, rec.TableName, reportsDir); err != nil {
			errors++
			h.Logger.Warn("failed to regenerate hourly report", "table", rec.TableName, "error", err)
			continue
		}
		regenerated++
	}

	resp := map[string]interface{}{
		"status":       "OK",
		"total":        len(records),
		"regenerated":  regenerated,
		"skipped":      skipped,
		"errors":       errors,
		"reports_dir":  reportsDir,
		"snapshotType": "hourly",
	}
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(resp)
}