package api

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

	"archivdms/internal/audit"
	"archivdms/internal/ldapstore"
	"archivdms/internal/userstore"
)

// resolveLDAPTenant determines which tenant's LDAP config the request targets.
// domain_admin is pinned to its own session tenant. superadmin (which has no
// session tenant) must pass ?tenant_id=; may also override to inspect any
// tenant. Returns the tenant ID and false when the request is not authorised
// or the tenant cannot be determined (the caller has already written nothing).
func (s *Server) resolveLDAPTenant(w http.ResponseWriter, r *http.Request) (int64, bool) {
	sess := sessionFromCtx(r.Context())

	// superadmin may target any tenant via ?tenant_id=.
	if sess.Role == userstore.RoleSuperAdmin {
		q := r.URL.Query().Get("tenant_id")
		if q == "" {
			writeError(w, http.StatusBadRequest, "tenant_id query parameter required for superadmin")
			return 0, false
		}
		tid, err := strconv.ParseInt(q, 10, 64)
		if err != nil || tid <= 0 {
			writeError(w, http.StatusBadRequest, "invalid tenant_id")
			return 0, false
		}
		return tid, true
	}

	// domain_admin: always scoped to its own tenant (IDOR-safe: query params
	// are ignored, the tenant comes from the signed session).
	if sess.TenantID == nil {
		writeError(w, http.StatusForbidden, "no tenant context")
		return 0, false
	}
	return *sess.TenantID, true
}

// handleGetLDAPConfig returns the tenant's LDAP config WITHOUT the bind
// password (only bind_password_set). Returns 404 when none is configured.
func (s *Server) handleGetLDAPConfig(w http.ResponseWriter, r *http.Request) {
	if s.ldapStore == nil {
		writeError(w, http.StatusServiceUnavailable, "ldap not configured on this server")
		return
	}
	tenantID, ok := s.resolveLDAPTenant(w, r)
	if !ok {
		return
	}

	cfg, err := s.ldapStore.Get(r.Context(), tenantID)
	if errors.Is(err, ldapstore.ErrNotFound) {
		writeError(w, http.StatusNotFound, "no ldap config for this tenant")
		return
	}
	if err != nil {
		writeError(w, http.StatusInternalServerError, "load ldap config failed")
		return
	}
	writeJSON(w, http.StatusOK, cfg)
}

type upsertLDAPConfigRequest struct {
	Enabled      bool    `json:"enabled"`
	Host         string  `json:"host"`
	Port         int     `json:"port"`
	UseTLS       string  `json:"use_tls"`
	BindDN       string  `json:"bind_dn"`
	BindPassword *string `json:"bind_password"` // nil = keep existing
	BaseDN       string  `json:"base_dn"`
	UserFilter   string  `json:"user_filter"`
	AttrUsername string  `json:"attr_username"`
	AttrEmail    string  `json:"attr_email"`
	AttrName     string  `json:"attr_name"`
	GroupBaseDN  string  `json:"group_base_dn"`
	GroupFilter  string  `json:"group_filter"`
	AdminGroupDN string  `json:"admin_group_dn"`
}

// handleUpsertLDAPConfig creates or updates the tenant's LDAP config. The bind
// password is optional (omit to keep the stored one); on creation it is
// mandatory. Every attempt — success or failure — is audit-logged.
func (s *Server) handleUpsertLDAPConfig(w http.ResponseWriter, r *http.Request) {
	sess := sessionFromCtx(r.Context())

	if s.ldapStore == nil {
		writeError(w, http.StatusServiceUnavailable, "ldap not configured on this server")
		return
	}
	tenantID, ok := s.resolveLDAPTenant(w, r)
	if !ok {
		return
	}

	logFail := func(detail string) {
		tid := tenantID
		s.audlog.Log(audit.Entry{
			EventType: audit.EventLdapConfigChanged, Username: sess.Username,
			TenantID: &tid, Success: false, Detail: detail,
		})
	}

	var req upsertLDAPConfigRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		logFail("invalid_body")
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	if req.Host == "" || req.BindDN == "" || req.BaseDN == "" {
		logFail("missing_fields")
		writeError(w, http.StatusBadRequest, "host, bind_dn and base_dn are required")
		return
	}

	// Defaults mirroring the schema so a minimal request still yields a
	// working config.
	if req.UserFilter == "" {
		req.UserFilter = "(uid=%s)"
	}
	if req.AttrUsername == "" {
		req.AttrUsername = "uid"
	}
	if req.AttrEmail == "" {
		req.AttrEmail = "mail"
	}
	if req.AttrName == "" {
		req.AttrName = "cn"
	}

	cfg := ldapstore.Config{
		TenantID:     tenantID,
		Enabled:      req.Enabled,
		Host:         req.Host,
		Port:         req.Port,
		UseTLS:       req.UseTLS,
		BindDN:       req.BindDN,
		BaseDN:       req.BaseDN,
		UserFilter:   req.UserFilter,
		AttrUsername: req.AttrUsername,
		AttrEmail:    req.AttrEmail,
		AttrName:     req.AttrName,
		GroupBaseDN:  req.GroupBaseDN,
		GroupFilter:  req.GroupFilter,
		AdminGroupDN: req.AdminGroupDN,
	}

	saved, err := s.ldapStore.Upsert(r.Context(), cfg, req.BindPassword)
	if err != nil {
		logFail("upsert_failed")
		writeError(w, http.StatusBadRequest, "save ldap config failed: "+err.Error())
		return
	}

	tid := tenantID
	s.audlog.Log(audit.Entry{
		EventType: audit.EventLdapConfigChanged, Username: sess.Username,
		TenantID: &tid, Success: true,
		Detail: "ldap_config_saved host:" + saved.Host,
	})
	writeJSON(w, http.StatusOK, saved)
}