package handler

import (
	"context"
	"fmt"
	"math"
	"net/http"
	"strings"
	"time"
	"vctp/db"
	"vctp/internal/vcenter"
	"vctp/server/models"
)

// VcenterCacheRebuild force-regenerates cached vCenter reference data in the database.
// @Summary Rebuild vCenter object cache
// @Description Rebuilds cached folder/resource-pool/host(cluster+datacenter) references from vCenter and rewrites the database cache tables.
// @Tags vcenters
// @Produce json
// @Param vcenter query string false "Optional single vCenter URL to rebuild; defaults to all configured vCenters"
// @Success 200 {object} models.VcenterCacheRebuildResponse "Cache rebuild summary"
// @Failure 400 {object} models.ErrorResponse "Invalid request"
// @Failure 405 {object} models.ErrorResponse "Method not allowed"
// @Failure 500 {object} models.VcenterCacheRebuildResponse "All rebuild attempts failed"
// @Router /api/vcenters/cache/rebuild [post]
func (h *Handler) VcenterCacheRebuild(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		writeJSONError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	ctx := r.Context()
	h.Settings.ReadYMLSettings()

	requested := strings.TrimSpace(r.URL.Query().Get("vcenter"))
	configured := h.Settings.Values.Settings.VcenterAddresses
	targets := make([]string, 0, len(configured))
	for _, raw := range configured {
		vcURL := strings.TrimSpace(raw)
		if vcURL == "" {
			continue
		}
		if requested != "" && vcURL != requested {
			continue
		}
		targets = append(targets, vcURL)
	}

	if requested != "" && len(targets) == 0 {
		writeJSONError(w, http.StatusBadRequest, fmt.Sprintf("requested vcenter is not configured: %s", requested))
		return
	}
	if len(targets) == 0 {
		writeJSONError(w, http.StatusBadRequest, "no vcenter addresses configured")
		return
	}

	if err := db.EnsureVcenterReferenceCacheTables(ctx, h.Database.DB()); err != nil {
		h.Logger.Error("failed to ensure vcenter cache tables", "error", err)
		writeJSONError(w, http.StatusInternalServerError, "failed to ensure vcenter cache tables")
		return
	}

	resp := models.VcenterCacheRebuildResponse{
		Status:  "OK",
		Total:   len(targets),
		Results: make([]models.VcenterCacheRebuildResult, 0, len(targets)),
	}

	for _, vcURL := range targets {
		start := time.Now()
		result := models.VcenterCacheRebuildResult{
			Vcenter: vcURL,
		}

		folderEntries, poolEntries, hostEntries, err := h.rebuildOneVcenterCache(ctx, vcURL)
		result.DurationSeconds = math.Round(time.Since(start).Seconds()*1000) / 1000
		if err != nil {
			result.Error = err.Error()
			resp.Failed++
			h.Logger.Warn("vcenter cache rebuild failed", "vcenter", vcURL, "error", err)
		} else {
			result.FolderEntries = folderEntries
			result.ResourcePoolEntries = poolEntries
			result.HostEntries = hostEntries
			resp.Succeeded++
			h.Logger.Info("vcenter cache rebuild completed", "vcenter", vcURL, "folder_entries", folderEntries, "resource_pool_entries", poolEntries, "host_entries", hostEntries, "duration", time.Since(start))
		}
		resp.Results = append(resp.Results, result)
	}

	switch {
	case resp.Failed == 0:
		resp.Status = "OK"
		writeJSON(w, http.StatusOK, resp)
	case resp.Succeeded == 0:
		resp.Status = "ERROR"
		writeJSON(w, http.StatusInternalServerError, resp)
	default:
		resp.Status = "PARTIAL"
		writeJSON(w, http.StatusOK, resp)
	}
}

func (h *Handler) rebuildOneVcenterCache(ctx context.Context, vcURL string) (int, int, int, error) {
	vc := vcenter.New(h.Logger, h.VcCreds)
	if err := vc.Login(vcURL); err != nil {
		return 0, 0, 0, fmt.Errorf("unable to connect to vcenter: %w", err)
	}
	defer func() {
		logoutCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		if err := vc.Logout(logoutCtx); err != nil {
			h.Logger.Warn("vcenter cache rebuild logout failed", "vcenter", vcURL, "error", err)
		}
	}()

	folderLookup, err := vc.BuildFolderPathLookup()
	if err != nil {
		return 0, 0, 0, fmt.Errorf("failed to build folder cache from vcenter: %w", err)
	}
	resourcePools, err := vc.BuildResourcePoolLookup()
	if err != nil {
		return 0, 0, 0, fmt.Errorf("failed to build resource pool cache from vcenter: %w", err)
	}
	hostLookup, err := vc.BuildHostLookup()
	if err != nil {
		return 0, 0, 0, fmt.Errorf("failed to build host cache from vcenter: %w", err)
	}

	dbConn := h.Database.DB()
	if err := db.ClearVcenterReferenceCache(ctx, dbConn, vcURL); err != nil {
		return 0, 0, 0, fmt.Errorf("failed to clear existing vcenter cache rows: %w", err)
	}
	lastSeen := time.Now().Unix()

	folderCount := 0
	for folderRef, folderPath := range folderLookup {
		if err := db.UpsertVcenterFolderCache(ctx, dbConn, vcURL, folderRef, folderPath, lastSeen); err != nil {
			return 0, 0, 0, fmt.Errorf("failed to persist folder cache: %w", err)
		}
		folderCount++
	}

	poolCount := 0
	for poolRef, poolName := range resourcePools {
		if err := db.UpsertVcenterResourcePoolCache(ctx, dbConn, vcURL, poolRef, poolName, lastSeen); err != nil {
			return 0, 0, 0, fmt.Errorf("failed to persist resource pool cache: %w", err)
		}
		poolCount++
	}

	hostCount := 0
	for hostRef, entry := range hostLookup {
		if err := db.UpsertVcenterHostCache(ctx, dbConn, vcURL, hostRef, entry.Cluster, entry.Datacenter, lastSeen); err != nil {
			return 0, 0, 0, fmt.Errorf("failed to persist host cache: %w", err)
		}
		hostCount++
	}

	return folderCount, poolCount, hostCount, nil
}