package commandcenter

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

	"github.com/go-chi/chi/v5"

	"github.com/missionworkforce/missionmatch/internal/platform/security"
	"github.com/missionworkforce/missionmatch/internal/platform/tenant"
)

// Handler serves the Workforce Command Center endpoint.
type Handler struct{ svc *Service }

func NewHandler(svc *Service) *Handler { return &Handler{svc: svc} }

// Routes mounts the Command Center endpoints under the tenant scoped group. The dashboard read is gated
// on candidate.read since the payload exposes candidate names and clearance (the same data class as GET
// /candidates). Adopting a forecast as a requirement is a write, gated on requirement.write.
func (h *Handler) Routes(r chi.Router) {
	r.With(security.RequireCapability(security.CapCandidateRead)).Get("/command-center", h.get)
	// The federal signal panel reads public federal data and the global mission tag and incumbent role
	// catalogs. It is gated on candidate.read like the dashboard since it shares the same surface, and it
	// is read only. The optional mission query parameter scopes the open by mission list to one code.
	r.With(security.RequireCapability(security.CapCandidateRead)).Get("/command-center/federal-signal", h.federalSignal)
	r.With(security.RequireCapability(security.CapRequirementEdit)).Post("/command-center/upcoming/{recordID}/adopt", h.adopt)
}

func (h *Handler) federalSignal(w http.ResponseWriter, r *http.Request) {
	mission := r.URL.Query().Get("mission")
	v, err := h.svc.FederalSignal(r.Context(), mission)
	if err != nil {
		switch {
		case errors.Is(err, errUnknownMission):
			writeJSONErr(w, http.StatusBadRequest, "unknown mission code")
		case errors.Is(err, tenant.ErrNoTenant):
			writeJSONErr(w, http.StatusForbidden, "no validated tenant")
		case errors.Is(err, ErrNoDatabase):
			writeJSONErr(w, http.StatusServiceUnavailable, "database not configured")
		default:
			writeJSONErr(w, http.StatusInternalServerError, "internal error")
		}
		return
	}
	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(v)
}

func (h *Handler) adopt(w http.ResponseWriter, r *http.Request) {
	recordID := chi.URLParam(r, "recordID")
	var in AdoptForecastInput
	dec := json.NewDecoder(http.MaxBytesReader(w, r.Body, 1<<20))
	dec.DisallowUnknownFields()
	if err := dec.Decode(&in); err != nil {
		writeJSONErr(w, http.StatusBadRequest, "invalid request body")
		return
	}
	res, err := h.svc.AdoptForecast(r.Context(), recordID, in)
	if err != nil {
		switch {
		case errors.Is(err, ErrForecastNotFound):
			writeJSONErr(w, http.StatusNotFound, "forecast not found")
		case errors.Is(err, ErrNotAForecast), errors.Is(err, ErrBadRequest):
			writeJSONErr(w, http.StatusBadRequest, "record is not an adoptable forecast")
		case errors.Is(err, tenant.ErrNoTenant):
			writeJSONErr(w, http.StatusForbidden, "no validated tenant")
		case errors.Is(err, ErrNoDatabase):
			writeJSONErr(w, http.StatusServiceUnavailable, "database not configured")
		default:
			writeJSONErr(w, http.StatusInternalServerError, "internal error")
		}
		return
	}
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	_ = json.NewEncoder(w).Encode(res)
}

func writeJSONErr(w http.ResponseWriter, status int, msg string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(map[string]string{"error": msg})
}

func (h *Handler) get(w http.ResponseWriter, r *http.Request) {
	asOf := h.svc.clock()
	if q := r.URL.Query().Get("as_of"); q != "" {
		if t, err := time.Parse("2006-01-02", q); err == nil {
			asOf = t
		}
	}
	v, err := h.svc.CommandCenter(r.Context(), asOf)
	if err != nil {
		w.Header().Set("Content-Type", "application/json")
		switch {
		case errors.Is(err, tenant.ErrNoTenant):
			w.WriteHeader(http.StatusForbidden)
			_, _ = w.Write([]byte(`{"error":"no validated tenant"}`))
		case errors.Is(err, ErrNoDatabase):
			w.WriteHeader(http.StatusServiceUnavailable)
			_, _ = w.Write([]byte(`{"error":"database not configured"}`))
		default:
			w.WriteHeader(http.StatusInternalServerError)
			_, _ = w.Write([]byte(`{"error":"internal error"}`))
		}
		return
	}
	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(v)
}