package handlers

import (
	"net/http"
	"regexp"
	"strconv"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/imc-vibe/backend/internal/db"
)

type DomainHandler struct {
	db *db.DB
}

func NewDomainHandler(database *db.DB) *DomainHandler {
	return &DomainHandler{db: database}
}

type CreateDomainRequest struct {
	Name string `json:"name" binding:"required"`
}

type DomainPermissions struct {
	DomainID   uint   `json:"domainId"`
	DomainName string `json:"domainName"`
	UserID     uint   `json:"userId"`
	CanManage  bool   `json:"canManage"`
}

func (h *DomainHandler) List(c *gin.Context) {
	authCtx := GetAuthContext(c)
	if authCtx == nil {
		Error(c, http.StatusUnauthorized, "authentication required")
		return
	}

	isAdmin := authCtx.IsAdmin()
	domains, err := h.db.GetUserAccessibleDomains(authCtx.UserID, isAdmin)
	if err != nil {
		Error(c, http.StatusInternalServerError, "database error")
		return
	}

	domainStats := make([]db.DomainStats, len(domains))
	for i, d := range domains {
		var userCount, aliasCount int64
		h.db.Model(&db.User{}).Where("domain_id = ?", d.ID).Count(&userCount)
		h.db.Model(&db.Alias{}).Where("domain_id = ?", d.ID).Count(&aliasCount)
		domainStats[i] = db.DomainStats{
			ID:         d.ID,
			Name:       d.Name,
			UserCount:  userCount,
			AliasCount: aliasCount,
		}
	}

	Success(c, domainStats)
}

func (h *DomainHandler) Get(c *gin.Context) {
	domainName := c.Param("name")
	if domainName == "" {
		Error(c, http.StatusBadRequest, "domain name required")
		return
	}

	domain, err := h.db.GetDomainByName(domainName)
	if err != nil {
		Error(c, http.StatusNotFound, "domain not found")
		return
	}

	authCtx := GetAuthContext(c)
	if authCtx == nil {
		Error(c, http.StatusUnauthorized, "authentication required")
		return
	}

	canAccess, _ := h.db.CanAccessDomain(authCtx.UserID, domainName, authCtx.IsAdmin())
	if !canAccess {
		Error(c, http.StatusForbidden, "access denied")
		return
	}

	Success(c, domain)
}

func (h *DomainHandler) Create(c *gin.Context) {
	authCtx := GetAuthContext(c)
	if authCtx == nil || !authCtx.IsAdmin() {
		Error(c, http.StatusForbidden, "admin access required")
		return
	}

	var req CreateDomainRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		Error(c, http.StatusBadRequest, "invalid request body")
		return
	}

	name := strings.ToLower(strings.TrimSpace(req.Name))
	if err := validateDomainName(name); err != nil {
		Error(c, http.StatusBadRequest, err.Error())
		return
	}

	existing, err := h.db.GetDomainByName(name)
	if err == nil && existing != nil {
		Error(c, http.StatusConflict, "domain already exists")
		return
	}

	domain, err := h.db.CreateDomain(name)
	if err != nil {
		Error(c, http.StatusInternalServerError, "failed to create domain")
		return
	}

	Created(c, domain)
}

func validateDomainName(name string) error {
	if len(name) < 3 || len(name) > 253 {
		return &ValidationError{Message: "domain name must be between 3 and 253 characters"}
	}

	if strings.Contains(name, "..") {
		return &ValidationError{Message: "domain name cannot contain consecutive dots"}
	}

	if strings.HasPrefix(name, ".") || strings.HasSuffix(name, ".") {
		return &ValidationError{Message: "domain name cannot start or end with a dot"}
	}

	if strings.HasPrefix(name, "-") || strings.HasSuffix(name, "-") {
		return &ValidationError{Message: "domain name cannot start or end with a hyphen"}
	}

	domainRegex := regexp.MustCompile(`^[a-z0-9]([a-z0-9.-]*[a-z0-9])?$`)
	if !domainRegex.MatchString(name) {
		return &ValidationError{Message: "domain name can only contain letters, numbers, dots, and hyphens"}
	}

	labels := strings.Split(name, ".")
	for _, label := range labels {
		if len(label) < 1 || len(label) > 63 {
			return &ValidationError{Message: "each part of the domain name must be between 1 and 63 characters"}
		}
	}

	return nil
}

type ValidationError struct {
	Message string
}

func (e *ValidationError) Error() string {
	return e.Message
}

func (h *DomainHandler) Delete(c *gin.Context) {
	authCtx := GetAuthContext(c)
	if authCtx == nil || !authCtx.IsAdmin() {
		Error(c, http.StatusForbidden, "admin access required")
		return
	}

	domainName := c.Param("name")
	if domainName == "" {
		Error(c, http.StatusBadRequest, "domain name required")
		return
	}

	domain, err := h.db.GetDomainByName(domainName)
	if err != nil {
		Error(c, http.StatusNotFound, "domain not found")
		return
	}

	if err := h.db.DeleteDomain(domain.ID); err != nil {
		Error(c, http.StatusInternalServerError, "failed to delete domain")
		return
	}

	NoContent(c)
}

func (h *DomainHandler) GetPermissions(c *gin.Context) {
	authCtx := GetAuthContext(c)
	if authCtx == nil {
		Error(c, http.StatusUnauthorized, "authentication required")
		return
	}

	if !authCtx.IsAdmin() {
		Error(c, http.StatusForbidden, "admin access required")
		return
	}

	domainName := c.Param("name")
	if domainName == "" {
		Error(c, http.StatusBadRequest, "domain name required")
		return
	}

	domain, err := h.db.GetDomainByName(domainName)
	if err != nil {
		Error(c, http.StatusNotFound, "domain not found")
		return
	}

	users, err := h.db.GetUsersForDomain(domain.ID)
	if err != nil {
		Error(c, http.StatusInternalServerError, "database error")
		return
	}

	permissions := make([]DomainPermissions, len(users))
	for i, u := range users {
		permissions[i] = DomainPermissions{
			DomainID:   domain.ID,
			DomainName: domain.Name,
			UserID:     u.ID,
			CanManage:  true,
		}
	}

	Success(c, permissions)
}

func (h *DomainHandler) AddPermission(c *gin.Context) {
	authCtx := GetAuthContext(c)
	if authCtx == nil || !authCtx.IsAdmin() {
		Error(c, http.StatusForbidden, "admin access required")
		return
	}

	domainName := c.Param("name")
	if domainName == "" {
		Error(c, http.StatusBadRequest, "domain name required")
		return
	}

	domain, err := h.db.GetDomainByName(domainName)
	if err != nil {
		Error(c, http.StatusNotFound, "domain not found")
		return
	}

	var req struct {
		UserID uint `json:"userId" binding:"required"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		Error(c, http.StatusBadRequest, "invalid request")
		return
	}

	if err := h.db.AddUserToDomain(req.UserID, domain.ID); err != nil {
		Error(c, http.StatusInternalServerError, "failed to add user to domain")
		return
	}

	Success(c, map[string]string{"message": "user added to domain"})
}

func (h *DomainHandler) RemovePermission(c *gin.Context) {
	authCtx := GetAuthContext(c)
	if authCtx == nil || !authCtx.IsAdmin() {
		Error(c, http.StatusForbidden, "admin access required")
		return
	}

	domainName := c.Param("name")
	if domainName == "" {
		Error(c, http.StatusBadRequest, "domain name required")
		return
	}

	domain, err := h.db.GetDomainByName(domainName)
	if err != nil {
		Error(c, http.StatusNotFound, "domain not found")
		return
	}

	userIDStr := c.Param("userId")
	userID, err := strconv.ParseUint(userIDStr, 10, 64)
	if err != nil {
		Error(c, http.StatusBadRequest, "invalid user id")
		return
	}

	if err := h.db.RemoveUserFromDomain(uint(userID), domain.ID); err != nil {
		Error(c, http.StatusInternalServerError, "failed to remove user from domain")
		return
	}

	NoContent(c)
}