package volunteer

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"strconv"

	"git.unsupervised.ca/walkies/internal/auth"
	"git.unsupervised.ca/walkies/internal/respond"
	"git.unsupervised.ca/walkies/internal/server/middleware"
	"github.com/go-chi/chi/v5"
)

// AuthServicer is the subset of auth.Service the Handler needs.
type AuthServicer interface {
	Login(ctx context.Context, email, password string) (int64, string, error)
}

type Handler struct {
	store   Storer
	authSvc AuthServicer
}

func NewHandler(store *Store, authSvc *auth.Service) *Handler {
	return &Handler{store: store, authSvc: authSvc}
}

// NewHandlerFromInterfaces constructs a Handler from interface values, intended for testing.
func NewHandlerFromInterfaces(store Storer, authSvc AuthServicer) *Handler {
	return &Handler{store: store, authSvc: authSvc}
}

// POST /api/v1/auth/login
func (h *Handler) Login(w http.ResponseWriter, r *http.Request) {
	var body struct {
		Email    string `json:"email"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		respond.Error(w, http.StatusBadRequest, "invalid request body")
		return
	}
	id, token, err := h.authSvc.Login(r.Context(), body.Email, body.Password)
	if err != nil {
		respond.Error(w, http.StatusUnauthorized, "invalid credentials")
		return
	}
	_ = h.store.RecordLogin(r.Context(), id)
	respond.JSON(w, http.StatusOK, map[string]string{"token": token})
}

// POST /api/v1/auth/activate
// Public endpoint — volunteer sets their password using an invite token.
func (h *Handler) Activate(w http.ResponseWriter, r *http.Request) {
	var body struct {
		Token    string `json:"token"`
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		respond.Error(w, http.StatusBadRequest, "invalid request body")
		return
	}
	if body.Token == "" || body.Password == "" {
		respond.Error(w, http.StatusBadRequest, "token and password are required")
		return
	}
	hashed, err := auth.HashPassword(body.Password)
	if err != nil {
		respond.Error(w, http.StatusInternalServerError, "could not hash password")
		return
	}
	v, err := h.store.Activate(r.Context(), body.Token, hashed)
	if errors.Is(err, ErrInvalidToken) {
		respond.Error(w, http.StatusBadRequest, "invalid or expired invite token")
		return
	}
	if err != nil {
		respond.Error(w, http.StatusInternalServerError, "could not activate account")
		return
	}
	respond.JSON(w, http.StatusOK, v)
}

// POST /api/v1/volunteers — admin only
func (h *Handler) Create(w http.ResponseWriter, r *http.Request) {
	var in CreateInput
	if err := json.NewDecoder(r.Body).Decode(&in); err != nil {
		respond.Error(w, http.StatusBadRequest, "invalid request body")
		return
	}
	if in.Name == "" || in.Email == "" {
		respond.Error(w, http.StatusBadRequest, "name and email are required")
		return
	}
	av, err := h.store.Create(r.Context(), in)
	if err != nil {
		respond.Error(w, http.StatusConflict, "email already in use")
		return
	}
	respond.JSON(w, http.StatusCreated, av)
}

// GET /api/v1/volunteers
func (h *Handler) List(w http.ResponseWriter, r *http.Request) {
	claims := middleware.ClaimsFromContext(r.Context())
	if claims != nil && claims.Role == "admin" {
		volunteers, err := h.store.ListAdmin(r.Context())
		if err != nil {
			respond.Error(w, http.StatusInternalServerError, "could not list volunteers")
			return
		}
		if volunteers == nil {
			volunteers = []AdminVolunteer{}
		}
		respond.JSON(w, http.StatusOK, volunteers)
		return
	}

	volunteers, err := h.store.List(r.Context(), true)
	if err != nil {
		respond.Error(w, http.StatusInternalServerError, "could not list volunteers")
		return
	}
	if volunteers == nil {
		volunteers = []Volunteer{}
	}
	respond.JSON(w, http.StatusOK, volunteers)
}

// GET /api/v1/volunteers/{id}
func (h *Handler) Get(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
	if err != nil {
		respond.Error(w, http.StatusBadRequest, "invalid id")
		return
	}
	claims := middleware.ClaimsFromContext(r.Context())
	if claims != nil && claims.Role == "admin" {
		av, err := h.store.GetAdminByID(r.Context(), id)
		if errors.Is(err, ErrNotFound) {
			respond.Error(w, http.StatusNotFound, "volunteer not found")
			return
		}
		if err != nil {
			respond.Error(w, http.StatusInternalServerError, "could not get volunteer")
			return
		}
		respond.JSON(w, http.StatusOK, av)
		return
	}

	v, err := h.store.GetByID(r.Context(), id)
	if errors.Is(err, ErrNotFound) {
		respond.Error(w, http.StatusNotFound, "volunteer not found")
		return
	}
	if err != nil {
		respond.Error(w, http.StatusInternalServerError, "could not get volunteer")
		return
	}
	respond.JSON(w, http.StatusOK, v)
}

// PUT /api/v1/volunteers/{id}
// Admins can update all fields. Volunteers can only update their own name and phone.
func (h *Handler) Update(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
	if err != nil {
		respond.Error(w, http.StatusBadRequest, "invalid id")
		return
	}
	claims := middleware.ClaimsFromContext(r.Context())
	if claims == nil {
		respond.Error(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	var in UpdateInput
	if err := json.NewDecoder(r.Body).Decode(&in); err != nil {
		respond.Error(w, http.StatusBadRequest, "invalid request body")
		return
	}

	// Volunteers can only update their own profile, and only name + phone.
	if claims.Role != "admin" {
		if claims.VolunteerID != id {
			respond.Error(w, http.StatusForbidden, "forbidden")
			return
		}
		restricted := UpdateInput{Name: in.Name, Phone: in.Phone}
		in = restricted
	}

	v, err := h.store.Update(r.Context(), id, in)
	if errors.Is(err, ErrNotFound) {
		respond.Error(w, http.StatusNotFound, "volunteer not found")
		return
	}
	if err != nil {
		respond.Error(w, http.StatusInternalServerError, "could not update volunteer")
		return
	}
	respond.JSON(w, http.StatusOK, v)
}

// POST /api/v1/volunteers/{id}/invite — admin only, resends invite token
func (h *Handler) ResendInvite(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
	if err != nil {
		respond.Error(w, http.StatusBadRequest, "invalid id")
		return
	}
	token, err := h.store.RotateInviteToken(r.Context(), id)
	if err != nil {
		respond.Error(w, http.StatusInternalServerError, "could not generate invite token")
		return
	}
	respond.JSON(w, http.StatusOK, map[string]string{"invite_token": token})
}