package server

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
	"time"

	"scm.bstein.dev/bstein/soteria/internal/api"
	"scm.bstein.dev/bstein/soteria/internal/config"
	"scm.bstein.dev/bstein/soteria/internal/k8s"
	"scm.bstein.dev/bstein/soteria/internal/longhorn"
)

type Server struct {
	cfg      *config.Config
	client   *k8s.Client
	longhorn *longhorn.Client
	mux      *http.ServeMux
}

func New(cfg *config.Config, client *k8s.Client, lh *longhorn.Client) *Server {
	s := &Server{
		cfg:      cfg,
		client:   client,
		longhorn: lh,
		mux:      http.NewServeMux(),
	}

	s.mux.HandleFunc("/healthz", s.handleHealth)
	s.mux.HandleFunc("/readyz", s.handleReady)
	s.mux.HandleFunc("/v1/backup", s.handleBackup)
	s.mux.HandleFunc("/v1/restore-test", s.handleRestore)

	return s
}

func (s *Server) Handler() http.Handler {
	return s.mux
}

func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

func (s *Server) handleReady(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, http.StatusOK, map[string]string{"status": "ready"})
}

func (s *Server) handleBackup(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
	var req api.BackupRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, fmt.Sprintf("invalid JSON: %v", err))
		return
	}

	switch s.cfg.BackupDriver {
	case "longhorn":
		volumeName, _, _, err := s.client.ResolvePVCVolume(r.Context(), req.Namespace, req.PVC)
		if err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}

		backupName := backupName("backup", req.PVC)
		if req.DryRun {
			writeJSON(w, http.StatusOK, api.BackupResponse{
				Driver:    "longhorn",
				Volume:    volumeName,
				Backup:    backupName,
				Namespace: req.Namespace,
				DryRun:    true,
			})
			return
		}

		labels := map[string]string{
			"soteria.bstein.dev/namespace": req.Namespace,
			"soteria.bstein.dev/pvc":       req.PVC,
		}
		if _, err := s.longhorn.SnapshotBackup(r.Context(), volumeName, backupName, labels, s.cfg.LonghornBackupMode); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}

		writeJSON(w, http.StatusOK, api.BackupResponse{
			Driver:    "longhorn",
			Volume:    volumeName,
			Backup:    backupName,
			Namespace: req.Namespace,
			DryRun:    false,
		})
	case "restic":
		jobName, secretName, err := s.client.CreateBackupJob(r.Context(), s.cfg, req)
		if err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}

		writeJSON(w, http.StatusOK, api.BackupResponse{
			Driver:    "restic",
			JobName:   jobName,
			Namespace: req.Namespace,
			Secret:    secretName,
			DryRun:    req.DryRun,
		})
	default:
		writeError(w, http.StatusBadRequest, "unsupported backup driver")
	}
}

func (s *Server) handleRestore(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
	var req api.RestoreTestRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, fmt.Sprintf("invalid JSON: %v", err))
		return
	}

	switch s.cfg.BackupDriver {
	case "longhorn":
		if req.TargetPVC == "" {
			writeError(w, http.StatusBadRequest, "target_pvc is required")
			return
		}
		if req.PVC == "" {
			writeError(w, http.StatusBadRequest, "pvc is required to locate backup volume")
			return
		}

		volumeName, _, _, err := s.client.ResolvePVCVolume(r.Context(), req.Namespace, req.PVC)
		if err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}

		backupURL := strings.TrimSpace(req.BackupURL)
		if backupURL == "" {
			backup, err := s.longhorn.FindBackup(r.Context(), volumeName, req.Snapshot)
			if err != nil {
				writeError(w, http.StatusBadRequest, err.Error())
				return
			}
			backupURL = backup.URL
		}
		if backupURL == "" {
			writeError(w, http.StatusBadRequest, "backup_url is required")
			return
		}

		restoreVolumeName := backupName("restore", req.TargetPVC)
		if req.DryRun {
			writeJSON(w, http.StatusOK, api.RestoreTestResponse{
				Driver:    "longhorn",
				Volume:    restoreVolumeName,
				TargetPVC: req.TargetPVC,
				BackupURL: backupURL,
				Namespace: req.Namespace,
				DryRun:    true,
			})
			return
		}

		sourceVolume, err := s.longhorn.GetVolume(r.Context(), volumeName)
		if err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		replicas := sourceVolume.NumberOfReplicas
		if replicas == 0 {
			replicas = 2
		}

		if _, err := s.longhorn.CreateVolumeFromBackup(r.Context(), restoreVolumeName, sourceVolume.Size, replicas, backupURL); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		if err := s.longhorn.CreatePVC(r.Context(), restoreVolumeName, req.Namespace, req.TargetPVC); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}

		writeJSON(w, http.StatusOK, api.RestoreTestResponse{
			Driver:    "longhorn",
			Volume:    restoreVolumeName,
			TargetPVC: req.TargetPVC,
			BackupURL: backupURL,
			Namespace: req.Namespace,
			DryRun:    false,
		})
	case "restic":
		jobName, secretName, err := s.client.CreateRestoreJob(r.Context(), s.cfg, req)
		if err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}

		writeJSON(w, http.StatusOK, api.RestoreTestResponse{
			Driver:    "restic",
			JobName:   jobName,
			Namespace: req.Namespace,
			Secret:    secretName,
			DryRun:    req.DryRun,
		})
	default:
		writeError(w, http.StatusBadRequest, "unsupported backup driver")
	}
}

func writeJSON(w http.ResponseWriter, status int, payload any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(payload)
}

func writeError(w http.ResponseWriter, status int, message string) {
	writeJSON(w, status, map[string]string{"error": message})
}

func backupName(prefix, value string) string {
	base := sanitizeName(fmt.Sprintf("soteria-%s-%s", prefix, value))
	timestamp := time.Now().UTC().Format("20060102-150405")
	name := fmt.Sprintf("%s-%s", base, timestamp)
	if len(name) <= 63 {
		return name
	}
	maxBase := 63 - len(timestamp) - 1
	if maxBase < 1 {
		maxBase = 1
	}
	if len(base) > maxBase {
		base = base[:maxBase]
	}
	return fmt.Sprintf("%s-%s", base, timestamp)
}

func sanitizeName(value string) string {
	value = strings.ToLower(value)
	value = strings.ReplaceAll(value, "_", "-")
	value = strings.ReplaceAll(value, ".", "-")
	value = strings.ReplaceAll(value, " ", "-")
	value = strings.Trim(value, "-")
	return value
}