// Package caseoverviewapi ist die HTTP-Bindung der workflow-eigenen
// Akten-Uebersicht (VOR-05). Nutzeridentitaet kommt uebergangsweise aus
// X-User-Id, wie bereits bei caseapi (VOR-01) und backchannelapi (VOR-04)
// etabliert.
package caseoverviewapi

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

	"gitea.perlbach24.de/scripte/nexarch/workflow/internal/caseobj"
	"gitea.perlbach24.de/scripte/nexarch/workflow/internal/caseoverview"
	"gitea.perlbach24.de/scripte/nexarch/workflow/internal/reminder"
)

type Server struct {
	svc *caseoverview.Service
	now func() time.Time
}

func NewServer(svc *caseoverview.Service) *Server {
	return &Server{svc: svc, now: time.Now}
}

// RegisterRoutes bindet die Uebersichts-Routen. Alle Routen verlangen
// X-User-Id, wie die uebrige workflow-eigene API.
func (s *Server) RegisterRoutes(mux *http.ServeMux) {
	mux.HandleFunc("GET /cases", s.requireUser(s.handleList))
	mux.HandleFunc("GET /cases/{id}/overview", s.requireUser(s.handleDetail))
	mux.HandleFunc("GET /reminders/kanban", s.requireUser(s.handleKanban))
	mux.HandleFunc("POST /reminders/{id}/move", s.requireUser(s.handleMove))
}

func (s *Server) requireUser(next func(w http.ResponseWriter, r *http.Request)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Header.Get("X-User-Id") == "" {
			writeError(w, http.StatusUnauthorized, "X-User-Id fehlt")
			return
		}
		next(w, r)
	}
}

func (s *Server) handleList(w http.ResponseWriter, r *http.Request) {
	status := r.URL.Query().Get("status")
	responsible := r.URL.Query().Get("responsible")
	cases, err := s.svc.List(r.Context(), status, responsible)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "akten konnten nicht gelesen werden")
		return
	}
	if cases == nil {
		cases = []caseobj.Case{}
	}
	writeJSON(w, http.StatusOK, cases)
}

func (s *Server) handleDetail(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	detail, err := s.svc.Detail(r.Context(), id)
	switch {
	case err == nil:
		writeJSON(w, http.StatusOK, detail)
	case errors.Is(err, caseobj.ErrNotFound):
		writeError(w, http.StatusNotFound, "akte nicht gefunden")
	default:
		writeError(w, http.StatusInternalServerError, "akte konnte nicht gelesen werden")
	}
}

func (s *Server) handleKanban(w http.ResponseWriter, r *http.Request) {
	items, err := s.svc.Kanban(r.Context(), s.now())
	if err != nil {
		writeError(w, http.StatusInternalServerError, "wiedervorlagen konnten nicht gelesen werden")
		return
	}
	if items == nil {
		items = []caseoverview.KanbanItem{}
	}
	writeJSON(w, http.StatusOK, items)
}

type moveRequest struct {
	Target string `json:"target"`
}

func (s *Server) handleMove(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	var req moveRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "ungueltiger anfrage-koerper")
		return
	}
	err := s.svc.Move(r.Context(), id, caseoverview.KanbanColumn(req.Target))
	switch {
	case err == nil:
		w.WriteHeader(http.StatusNoContent)
	case errors.Is(err, reminder.ErrNotFound):
		writeError(w, http.StatusNotFound, "wiedervorlage nicht gefunden")
	default:
		writeError(w, http.StatusInternalServerError, "wiedervorlage konnte nicht verschoben werden")
	}
}

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

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