// Wiedervorlage (reminder) HTTP handlers:
//   POST   /api/documents/{id}/reminders
//   GET    /api/reminders?status=
//   PATCH  /api/reminders/{id}
//   DELETE /api/reminders/{id}
//
// All routes require s.auth(...) (authenticated + tenant context). Ownership
// is enforced in the store layer (id+tenant_id+user_id). Every mutation is
// audit-logged, including failures.
package api

import (
	"encoding/json"
	"net/http"
	"strconv"
	"time"

	"archivdms/internal/audit"
	"archivdms/internal/storage"
)

type createReminderRequest struct {
	DueDate string `json:"due_date"` // RFC3339
	Note    string `json:"note"`
}

// handleCreateReminder handles POST /api/documents/{id}/reminders.
func (s *Server) handleCreateReminder(w http.ResponseWriter, r *http.Request) {
	sess := sessionFromCtx(r.Context())
	if sess.TenantID == nil {
		writeError(w, http.StatusForbidden, "tenant context required")
		return
	}
	docID, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid document id")
		return
	}

	var req createReminderRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	dueDate, err := time.Parse(time.RFC3339, req.DueDate)
	if err != nil {
		writeError(w, http.StatusBadRequest, "due_date must be RFC3339")
		return
	}

	// Verify the document exists and belongs to the caller's tenant before
	// attaching a reminder to it (the FK alone would only stop a fully
	// nonexistent document_id, not a cross-tenant one).
	if _, err := s.store.GetDocument(r.Context(), docID, *sess.TenantID); err != nil {
		writeError(w, http.StatusNotFound, "document not found")
		return
	}

	rem, err := s.store.CreateReminder(r.Context(), docID, *sess.TenantID, sess.UserID, dueDate, req.Note)
	if err != nil {
		s.audlog.Log(audit.Entry{
			EventType: audit.EventReminderCreate, Username: sess.Username, TenantID: sess.TenantID,
			DocumentID: strconv.FormatInt(docID, 10), Success: false, Detail: err.Error(),
		})
		writeError(w, http.StatusInternalServerError, "create reminder failed")
		return
	}

	s.audlog.Log(audit.Entry{
		EventType: audit.EventReminderCreate, Username: sess.Username, TenantID: sess.TenantID,
		DocumentID: strconv.FormatInt(docID, 10), Success: true,
		Detail: "reminder_id:" + strconv.FormatInt(rem.ID, 10),
	})
	writeJSON(w, http.StatusCreated, rem)
}

// handleListReminders handles GET /api/reminders?status=.
func (s *Server) handleListReminders(w http.ResponseWriter, r *http.Request) {
	sess := sessionFromCtx(r.Context())
	if sess.TenantID == nil {
		writeError(w, http.StatusForbidden, "tenant context required")
		return
	}
	status := r.URL.Query().Get("status")
	if status != "" && status != storage.ReminderStatusOpen && status != storage.ReminderStatusDone && status != storage.ReminderStatusDismissed {
		writeError(w, http.StatusBadRequest, "invalid status filter")
		return
	}

	reminders, err := s.store.ListReminders(r.Context(), *sess.TenantID, sess.UserID, status)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "list reminders failed")
		return
	}
	writeJSON(w, http.StatusOK, reminders)
}

type updateReminderRequest struct {
	Status string `json:"status"`
}

// handleUpdateReminder handles PATCH /api/reminders/{id}.
func (s *Server) handleUpdateReminder(w http.ResponseWriter, r *http.Request) {
	sess := sessionFromCtx(r.Context())
	if sess.TenantID == nil {
		writeError(w, http.StatusForbidden, "tenant context required")
		return
	}
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid reminder id")
		return
	}
	var req updateReminderRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	switch req.Status {
	case storage.ReminderStatusOpen, storage.ReminderStatusDone, storage.ReminderStatusDismissed:
	default:
		writeError(w, http.StatusBadRequest, "invalid status")
		return
	}

	rem, err := s.store.UpdateReminderStatus(r.Context(), id, *sess.TenantID, sess.UserID, req.Status)
	if err != nil {
		s.audlog.Log(audit.Entry{
			EventType: audit.EventReminderStatusChange, Username: sess.Username, TenantID: sess.TenantID,
			Detail: "reminder_id:" + strconv.FormatInt(id, 10) + " err:" + err.Error(), Success: false,
		})
		writeError(w, http.StatusNotFound, "reminder not found")
		return
	}

	s.audlog.Log(audit.Entry{
		EventType: audit.EventReminderStatusChange, Username: sess.Username, TenantID: sess.TenantID,
		DocumentID: strconv.FormatInt(rem.DocumentID, 10), Success: true,
		Detail: "reminder_id:" + strconv.FormatInt(rem.ID, 10) + " status:" + rem.Status,
	})
	writeJSON(w, http.StatusOK, rem)
}

// handleDeleteReminder handles DELETE /api/reminders/{id}.
func (s *Server) handleDeleteReminder(w http.ResponseWriter, r *http.Request) {
	sess := sessionFromCtx(r.Context())
	if sess.TenantID == nil {
		writeError(w, http.StatusForbidden, "tenant context required")
		return
	}
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid reminder id")
		return
	}

	if err := s.store.DeleteReminder(r.Context(), id, *sess.TenantID, sess.UserID); err != nil {
		s.audlog.Log(audit.Entry{
			EventType: audit.EventReminderDelete, Username: sess.Username, TenantID: sess.TenantID,
			Detail: "reminder_id:" + strconv.FormatInt(id, 10) + " err:" + err.Error(), Success: false,
		})
		writeError(w, http.StatusNotFound, "reminder not found")
		return
	}

	s.audlog.Log(audit.Entry{
		EventType: audit.EventReminderDelete, Username: sess.Username, TenantID: sess.TenantID,
		Detail: "reminder_id:" + strconv.FormatInt(id, 10), Success: true,
	})
	writeJSON(w, http.StatusOK, map[string]string{"status": "deleted"})
}