package httpapi

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"

	"github.com/jackc/pgx/v5/pgconn"
	"github.com/vasyansk/imap-copier/internal/store"
)

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

func (s *Server) handleCreateEndpoint(w http.ResponseWriter, r *http.Request) {
	var e store.Endpoint
	if err := json.NewDecoder(r.Body).Decode(&e); err != nil {
		http.Error(w, "bad json", http.StatusBadRequest)
		return
	}
	if e.TLSMode != "ssl" && e.TLSMode != "starttls" && e.TLSMode != "plain" {
		http.Error(w, "tls_mode must be ssl|starttls|plain", http.StatusBadRequest)
		return
	}
	id, err := s.store.CreateEndpoint(r.Context(), e)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusCreated, map[string]int64{"id": id})
}

func (s *Server) handleUpdateEndpoint(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r, "id")
	if err != nil {
		http.Error(w, "bad id", http.StatusBadRequest)
		return
	}
	var e store.Endpoint
	if err := json.NewDecoder(r.Body).Decode(&e); err != nil {
		http.Error(w, "bad json", http.StatusBadRequest)
		return
	}
	if e.TLSMode != "ssl" && e.TLSMode != "starttls" && e.TLSMode != "plain" {
		http.Error(w, "tls_mode must be ssl|starttls|plain", http.StatusBadRequest)
		return
	}
	e.ID = id
	if err := s.store.UpdateEndpoint(r.Context(), e); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// handleDeleteEndpoint removes an endpoint that no task references. A referenced
// endpoint is refused with 409 rather than a foreign-key error, and the same
// status covers the race where a task is created between check and delete.
func (s *Server) handleDeleteEndpoint(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r, "id")
	if err != nil {
		http.Error(w, "bad id", http.StatusBadRequest)
		return
	}
	used, err := s.store.CountTasksUsingEndpoint(r.Context(), id)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	if used > 0 {
		http.Error(w, fmt.Sprintf("endpoint is used by %d task(s) — delete them first", used), http.StatusConflict)
		return
	}
	if err := s.store.DeleteEndpoint(r.Context(), id); err != nil {
		var pgErr *pgconn.PgError
		if errors.As(err, &pgErr) && pgErr.Code == "23503" {
			http.Error(w, "endpoint is used by a task — delete it first", http.StatusConflict)
			return
		}
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (s *Server) handleListEndpoints(w http.ResponseWriter, r *http.Request) {
	eps, err := s.store.ListEndpoints(r.Context())
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusOK, eps)
}