package handler

import (
	"errors"
	"net/http"
	"strings"

	jsoniter "github.com/json-iterator/go"

	"github.com/gofrs/uuid/v5"

	"github.com/saveinmed/backend-go/internal/domain"
	"github.com/saveinmed/backend-go/internal/usecase"
)

var json = jsoniter.ConfigCompatibleWithStandardLibrary

type Handler struct {
	svc *usecase.Service
}

func New(svc *usecase.Service) *Handler {
	return &Handler{svc: svc}
}

// Register godoc
// @Summary Cadastro de usuário
// @Description Cria um usuário e opcionalmente uma empresa, retornando token JWT.
// @Tags Autenticação
// @Accept json
// @Produce json
// @Param payload body registerAuthRequest true "Dados do usuário e empresa"
// @Success 201 {object} authResponse
// @Failure 400 {object} map[string]string
// @Failure 500 {object} map[string]string
// @Router /api/v1/auth/register [post]
func (h *Handler) Register(w http.ResponseWriter, r *http.Request) {
	var req registerAuthRequest
	if err := decodeJSON(r.Context(), r, &req); err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	var company *domain.Company
	if req.Company != nil {
		company = &domain.Company{
			ID:            req.Company.ID,
			Role:          req.Company.Role,
			CNPJ:          req.Company.CNPJ,
			CorporateName: req.Company.CorporateName,
			LicenseNumber: req.Company.LicenseNumber,
		}
	}

	var companyID uuid.UUID
	if req.CompanyID != nil {
		companyID = *req.CompanyID
	}

	user := &domain.User{
		CompanyID: companyID,
		Role:      req.Role,
		Name:      req.Name,
		Email:     req.Email,
	}

	if user.CompanyID == uuid.Nil && company == nil {
		writeError(w, http.StatusBadRequest, errors.New("company_id or company payload is required"))
		return
	}

	if err := h.svc.RegisterAccount(r.Context(), company, user, req.Password); err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	token, exp, err := h.svc.Authenticate(r.Context(), user.Email, req.Password)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusCreated, authResponse{Token: token, ExpiresAt: exp})
}

// Login godoc
// @Summary Login
// @Description Autentica usuário e retorna token JWT.
// @Tags Autenticação
// @Accept json
// @Produce json
// @Param payload body loginRequest true "Credenciais"
// @Success 200 {object} authResponse
// @Failure 400 {object} map[string]string
// @Failure 401 {object} map[string]string
// @Router /api/v1/auth/login [post]
func (h *Handler) Login(w http.ResponseWriter, r *http.Request) {
	var req loginRequest
	if err := decodeJSON(r.Context(), r, &req); err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	token, exp, err := h.svc.Authenticate(r.Context(), req.Email, req.Password)
	if err != nil {
		writeError(w, http.StatusUnauthorized, err)
		return
	}

	writeJSON(w, http.StatusOK, authResponse{Token: token, ExpiresAt: exp})
}

// CreatePaymentPreference godoc
// @Summary Cria preferência de pagamento Mercado Pago com split nativo
// @Tags Pagamentos
// @Security BearerAuth
// @Produce json
// @Param id path string true "Order ID"
// @Success 201 {object} domain.PaymentPreference
// @Router /api/v1/orders/{id}/payment [post]
func (h *Handler) CreatePaymentPreference(w http.ResponseWriter, r *http.Request) {
	if !strings.HasSuffix(r.URL.Path, "/payment") {
		http.NotFound(w, r)
		return
	}

	id, err := parseUUIDFromPath(r.URL.Path)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	pref, err := h.svc.CreatePaymentPreference(r.Context(), id)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusCreated, pref)
}

// CreateShipment godoc
// @Summary Gera guia de postagem/transporte
// @Tags Logistica
// @Security BearerAuth
// @Accept json
// @Produce json
// @Param shipment body createShipmentRequest true "Dados de envio"
// @Success 201 {object} domain.Shipment
// @Router /api/v1/shipments [post]
func (h *Handler) CreateShipment(w http.ResponseWriter, r *http.Request) {
	var req createShipmentRequest
	if err := decodeJSON(r.Context(), r, &req); err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	shipment := &domain.Shipment{
		OrderID:          req.OrderID,
		Carrier:          req.Carrier,
		TrackingCode:     req.TrackingCode,
		ExternalTracking: req.ExternalTracking,
	}

	if err := h.svc.CreateShipment(r.Context(), shipment); err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusCreated, shipment)
}

// GetShipmentByOrderID godoc
// @Summary Rastreia entrega
// @Tags Logistica
// @Security BearerAuth
// @Produce json
// @Param order_id path string true "Order ID"
// @Success 200 {object} domain.Shipment
// @Router /api/v1/shipments/{order_id} [get]
func (h *Handler) GetShipmentByOrderID(w http.ResponseWriter, r *http.Request) {
	orderID, err := parseUUIDFromPath(r.URL.Path)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	shipment, err := h.svc.GetShipmentByOrderID(r.Context(), orderID)
	if err != nil {
		writeError(w, http.StatusNotFound, err)
		return
	}

	writeJSON(w, http.StatusOK, shipment)
}

// HandlePaymentWebhook godoc
// @Summary Recebe notificações do Mercado Pago
// @Tags Pagamentos
// @Accept json
// @Produce json
// @Param notification body domain.PaymentWebhookEvent true "Evento do gateway"
// @Success 200 {object} domain.PaymentSplitResult
// @Router /api/v1/payments/webhook [post]
func (h *Handler) HandlePaymentWebhook(w http.ResponseWriter, r *http.Request) {
	var event domain.PaymentWebhookEvent
	if err := decodeJSON(r.Context(), r, &event); err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	summary, err := h.svc.HandlePaymentWebhook(r.Context(), event)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusOK, summary)
}

// GetSellerDashboard aggregates KPIs for the authenticated seller or the requested company.
// @Summary Dashboard do vendedor
// @Tags Dashboard
// @Security BearerAuth
// @Produce json
// @Param seller_id query string false "Seller ID"
// @Success 200 {object} domain.SellerDashboard
// @Router /api/v1/dashboard/seller [get]
func (h *Handler) GetSellerDashboard(w http.ResponseWriter, r *http.Request) {
	requester, err := getRequester(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	sellerID := requester.CompanyID
	if sid := r.URL.Query().Get("seller_id"); sid != "" {
		id, err := uuid.FromString(sid)
		if err != nil {
			writeError(w, http.StatusBadRequest, errors.New("invalid seller_id"))
			return
		}
		sellerID = &id
	}

	if sellerID == nil {
		writeError(w, http.StatusBadRequest, errors.New("seller context is required"))
		return
	}

	if !strings.EqualFold(requester.Role, "Admin") && requester.CompanyID != nil && *sellerID != *requester.CompanyID {
		writeError(w, http.StatusForbidden, errors.New("not allowed to view other sellers"))
		return
	}

	dashboard, err := h.svc.GetSellerDashboard(r.Context(), *sellerID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusOK, dashboard)
}

// GetAdminDashboard exposes platform-wide aggregated metrics.
// @Summary Dashboard do administrador
// @Tags Dashboard
// @Security BearerAuth
// @Produce json
// @Success 200 {object} domain.AdminDashboard
// @Router /api/v1/dashboard/admin [get]
func (h *Handler) GetAdminDashboard(w http.ResponseWriter, r *http.Request) {
	requester, err := getRequester(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	if !strings.EqualFold(requester.Role, "Admin") {
		writeError(w, http.StatusForbidden, errors.New("admin role required"))
		return
	}

	dashboard, err := h.svc.GetAdminDashboard(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusOK, dashboard)
}

// CreateUser godoc
// @Summary Criar usuário
// @Tags Usuários
// @Security BearerAuth
// @Accept json
// @Produce json
// @Param payload body createUserRequest true "Novo usuário"
// @Success 201 {object} domain.User
// @Failure 400 {object} map[string]string
// @Failure 403 {object} map[string]string
// @Failure 500 {object} map[string]string
// @Router /api/v1/users [post]
func (h *Handler) CreateUser(w http.ResponseWriter, r *http.Request) {
	requester, err := getRequester(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	var req createUserRequest
	if err := decodeJSON(r.Context(), r, &req); err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	if strings.EqualFold(requester.Role, "Seller") {
		if requester.CompanyID == nil {
			writeError(w, http.StatusBadRequest, errors.New("seller must include X-Company-ID header"))
			return
		}
		if req.CompanyID != *requester.CompanyID {
			writeError(w, http.StatusForbidden, errors.New("seller can only manage their own company users"))
			return
		}
	}

	user := &domain.User{
		CompanyID: req.CompanyID,
		Role:      req.Role,
		Name:      req.Name,
		Email:     req.Email,
	}

	if err := h.svc.CreateUser(r.Context(), user, req.Password); err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusCreated, user)
}

// ListUsers godoc
// @Summary Listar usuários
// @Tags Usuários
// @Security BearerAuth
// @Produce json
// @Param page query int false "Página"
// @Param page_size query int false "Tamanho da página"
// @Param company_id query string false "Filtro por empresa"
// @Success 200 {object} domain.UserPage
// @Failure 400 {object} map[string]string
// @Failure 500 {object} map[string]string
// @Router /api/v1/users [get]
func (h *Handler) ListUsers(w http.ResponseWriter, r *http.Request) {
	requester, err := getRequester(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	page, pageSize := parsePagination(r)

	var companyFilter *uuid.UUID
	if cid := r.URL.Query().Get("company_id"); cid != "" {
		id, err := uuid.FromString(cid)
		if err != nil {
			writeError(w, http.StatusBadRequest, errors.New("invalid company_id"))
			return
		}
		companyFilter = &id
	}

	if strings.EqualFold(requester.Role, "Seller") {
		if requester.CompanyID == nil {
			writeError(w, http.StatusBadRequest, errors.New("seller must include X-Company-ID header"))
			return
		}
		companyFilter = requester.CompanyID
	}

	pageResult, err := h.svc.ListUsers(r.Context(), domain.UserFilter{CompanyID: companyFilter}, page, pageSize)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusOK, pageResult)
}

// GetUser godoc
// @Summary Obter usuário
// @Tags Usuários
// @Security BearerAuth
// @Produce json
// @Param id path string true "User ID"
// @Success 200 {object} domain.User
// @Failure 400 {object} map[string]string
// @Failure 403 {object} map[string]string
// @Failure 404 {object} map[string]string
// @Router /api/v1/users/{id} [get]
func (h *Handler) GetUser(w http.ResponseWriter, r *http.Request) {
	requester, err := getRequester(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	id, err := parseUUIDFromPath(r.URL.Path)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	user, err := h.svc.GetUser(r.Context(), id)
	if err != nil {
		writeError(w, http.StatusNotFound, err)
		return
	}

	if strings.EqualFold(requester.Role, "Seller") {
		if requester.CompanyID == nil || user.CompanyID != *requester.CompanyID {
			writeError(w, http.StatusForbidden, errors.New("seller can only view users from their company"))
			return
		}
	}

	writeJSON(w, http.StatusOK, user)
}

// UpdateUser godoc
// @Summary Atualizar usuário
// @Tags Usuários
// @Security BearerAuth
// @Accept json
// @Produce json
// @Param id path string true "User ID"
// @Param payload body updateUserRequest true "Campos para atualização"
// @Success 200 {object} domain.User
// @Failure 400 {object} map[string]string
// @Failure 403 {object} map[string]string
// @Failure 404 {object} map[string]string
// @Failure 500 {object} map[string]string
// @Router /api/v1/users/{id} [put]
func (h *Handler) UpdateUser(w http.ResponseWriter, r *http.Request) {
	requester, err := getRequester(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	id, err := parseUUIDFromPath(r.URL.Path)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	var req updateUserRequest
	if err := decodeJSON(r.Context(), r, &req); err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	user, err := h.svc.GetUser(r.Context(), id)
	if err != nil {
		writeError(w, http.StatusNotFound, err)
		return
	}

	if strings.EqualFold(requester.Role, "Seller") {
		if requester.CompanyID == nil || user.CompanyID != *requester.CompanyID {
			writeError(w, http.StatusForbidden, errors.New("seller can only update their company users"))
			return
		}
	}

	if req.CompanyID != nil {
		user.CompanyID = *req.CompanyID
	}
	if req.Role != nil {
		user.Role = *req.Role
	}
	if req.Name != nil {
		user.Name = *req.Name
	}
	if req.Email != nil {
		user.Email = *req.Email
	}

	newPassword := ""
	if req.Password != nil {
		newPassword = *req.Password
	}

	if err := h.svc.UpdateUser(r.Context(), user, newPassword); err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	writeJSON(w, http.StatusOK, user)
}

// DeleteUser godoc
// @Summary Excluir usuário
// @Tags Usuários
// @Security BearerAuth
// @Param id path string true "User ID"
// @Success 204 {string} string "No Content"
// @Failure 400 {object} map[string]string
// @Failure 403 {object} map[string]string
// @Failure 404 {object} map[string]string
// @Failure 500 {object} map[string]string
// @Router /api/v1/users/{id} [delete]
func (h *Handler) DeleteUser(w http.ResponseWriter, r *http.Request) {
	requester, err := getRequester(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	id, err := parseUUIDFromPath(r.URL.Path)
	if err != nil {
		writeError(w, http.StatusBadRequest, err)
		return
	}

	user, err := h.svc.GetUser(r.Context(), id)
	if err != nil {
		writeError(w, http.StatusNotFound, err)
		return
	}

	if strings.EqualFold(requester.Role, "Seller") {
		if requester.CompanyID == nil || user.CompanyID != *requester.CompanyID {
			writeError(w, http.StatusForbidden, errors.New("seller can only delete their company users"))
			return
		}
	}

	if err := h.svc.DeleteUser(r.Context(), id); err != nil {
		writeError(w, http.StatusInternalServerError, err)
		return
	}

	w.WriteHeader(http.StatusNoContent)
}