package handlers

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

import "codit/internal/middleware"
import "codit/internal/models"

const permissionProjectCreate string = "project.create"

type meResponse struct {
	ID          string   `json:"id"`
	Username    string   `json:"username"`
	DisplayName string   `json:"display_name"`
	Email       string   `json:"email"`
	IsAdmin     bool     `json:"is_admin"`
	Disabled    bool     `json:"disabled"`
	AuthSource  string   `json:"auth_source"`
	CreatedAt   int64    `json:"created_at"`
	UpdatedAt   int64    `json:"updated_at"`
	Permissions []string `json:"permissions,omitempty"`
}

type subjectPermissionTargetRequest struct {
	SubjectType string `json:"subject_type"`
	SubjectID   string `json:"subject_id"`
}

type subjectPermissionRequest struct {
	Permission string                           `json:"permission"`
	Targets    []subjectPermissionTargetRequest `json:"targets"`
}

func (api *API) ListSubjectPermissions(w http.ResponseWriter, r *http.Request, _ map[string]string) {
	var permission string
	var subjectType string
	var subjectID string
	var items []models.SubjectPermission
	var err error
	if !api.requireAdmin(w, r) {
		return
	}
	permission = strings.TrimSpace(r.URL.Query().Get("permission"))
	subjectType = strings.TrimSpace(r.URL.Query().Get("subject_type"))
	subjectID = strings.TrimSpace(r.URL.Query().Get("subject_id"))
	items, err = api.store(r).ListSubjectPermissions(permission, subjectType, subjectID)
	if err != nil {
		WriteJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}
	WriteJSON(w, http.StatusOK, items)
}

func (api *API) CreateSubjectPermissions(w http.ResponseWriter, r *http.Request, _ map[string]string) {
	var req subjectPermissionRequest
	var permission string
	var targets []models.SubjectPermission
	var items []models.SubjectPermission
	var item models.SubjectPermission
	var i int
	var err error
	if !api.requireAdmin(w, r) {
		return
	}
	err = DecodeJSON(r, &req)
	if err != nil {
		WriteJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid request"})
		return
	}
	permission, err = normalizeSubjectPermissionName(req.Permission)
	if err != nil {
		WriteJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
		return
	}
	targets, err = normalizeSubjectPermissionTargets(permission, req.Targets)
	if err != nil {
		WriteJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
		return
	}
	for i = 0; i < len(targets); i++ {
		targets[i].Permission = permission
		item, err = api.store(r).UpsertSubjectPermission(targets[i])
		if err != nil {
			WriteJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
			return
		}
		items = append(items, item)
	}
	WriteJSON(w, http.StatusCreated, items)
}

func (api *API) DeleteSubjectPermission(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var permission string
	var subjectType string
	var subjectID string
	var err error
	if !api.requireAdmin(w, r) {
		return
	}
	permission, err = normalizeSubjectPermissionName(params["permission"])
	if err != nil {
		WriteJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
		return
	}
	subjectType = strings.ToLower(strings.TrimSpace(params["subjectType"]))
	subjectID = strings.TrimSpace(params["subjectID"])
	if subjectType != "user" && subjectType != "group" && subjectType != "principal" {
		WriteJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid subject_type"})
		return
	}
	if subjectID == "" {
		WriteJSON(w, http.StatusBadRequest, map[string]string{"error": "subject_id is required"})
		return
	}
	err = api.store(r).DeleteSubjectPermission(permission, subjectType, subjectID)
	if err != nil {
		WriteJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}
	WriteJSON(w, http.StatusOK, map[string]string{"status": "deleted"})
}

func (api *API) requirePermission(w http.ResponseWriter, r *http.Request, permission string) bool {
	var user models.User
	var principal models.ServicePrincipal
	var ok bool
	var allowed bool
	var err error
	user, ok = middleware.UserFromContext(r.Context())
	if ok {
		if user.IsAdmin {
			return true
		}
		allowed, err = api.store(r).UserHasPermission(user.ID, permission)
		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			return false
		}
		if allowed {
			return true
		}
		w.WriteHeader(http.StatusForbidden)
		return false
	}
	principal, ok = middleware.PrincipalFromContext(r.Context())
	if !ok || principal.Disabled {
		w.WriteHeader(http.StatusUnauthorized)
		return false
	}
	if principal.IsAdmin {
		return true
	}
	allowed, err = api.store(r).PrincipalHasPermission(principal.ID, permission)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		return false
	}
	if allowed {
		return true
	}
	w.WriteHeader(http.StatusForbidden)
	return false
}

func buildMeResponse(user models.User, permissions []string) meResponse {
	return meResponse{
		ID:          user.ID,
		Username:    user.Username,
		DisplayName: user.DisplayName,
		Email:       user.Email,
		IsAdmin:     user.IsAdmin,
		Disabled:    user.Disabled,
		AuthSource:  user.AuthSource,
		CreatedAt:   user.CreatedAt,
		UpdatedAt:   user.UpdatedAt,
		Permissions: permissions,
	}
}

func normalizeSubjectPermissionName(raw string) (string, error) {
	var value string
	value = strings.TrimSpace(raw)
	switch value {
	case permissionProjectCreate:
		return value, nil
	default:
		return "", errors.New("unsupported permission")
	}
}

func normalizeSubjectPermissionTargets(permission string, raw []subjectPermissionTargetRequest) ([]models.SubjectPermission, error) {
	var items []models.SubjectPermission
	var seen map[string]bool
	var subjectType string
	var subjectID string
	var key string
	var i int
	seen = make(map[string]bool)
	for i = 0; i < len(raw); i++ {
		subjectType = strings.ToLower(strings.TrimSpace(raw[i].SubjectType))
		subjectID = strings.TrimSpace(raw[i].SubjectID)
		if subjectType != "user" && subjectType != "group" && subjectType != "principal" {
			return nil, errors.New("invalid subject_type")
		}
		if permission == permissionProjectCreate && subjectType == "principal" {
			return nil, errors.New("project.create can only target users or groups")
		}
		if subjectID == "" {
			return nil, errors.New("subject_id is required")
		}
		key = subjectType + ":" + subjectID
		if seen[key] {
			continue
		}
		seen[key] = true
		items = append(items, models.SubjectPermission{
			SubjectType: subjectType,
			SubjectID:   subjectID,
		})
	}
	if len(items) == 0 {
		return nil, errors.New("at least one target is required")
	}
	return items, nil
}