package service

import (
	"context"
	"strings"

	"go.infratographer.com/x/gidx"
	"golang.org/x/exp/slices"

	"go.equinixmetal.net/infra9-metal-bridge/internal/permissions"
)

// processMemberships determines the changes between what is wanted and what is live and executes on the differences.
// If skipDeletions is true, no deletes will be executed.
func (s *service) processMemberships(ctx context.Context, relationships Relationships, skipDeletions bool) (int, int) {
	if len(relationships.Memberships) == 0 {
		return 0, 0
	}

	rlogger := s.logger.With("resource.id", relationships.Resource.PrefixedID())

	roleIDs := make(map[string]gidx.PrefixedID)

	var (
		totalRoleCreate, totalRoleDelete   int
		totalRoleAssign, totalRoleUnassign int
	)

	wantRoles, wantAssignments := s.mapResourceWants(relationships.Memberships)

	liveRoles, liveAssignments, err := s.mapResourceDetails(ctx, relationships.Resource.PrefixedID())
	if err != nil {
		rlogger.Errorw("failed to get membership resource details map",
			"error", err,
		)

		return 0, 0
	}

	roleCreations := make(map[string][]string)
	roleDeletions := make([]gidx.PrefixedID, 0)

	for roleKey, actions := range wantRoles {
		if _, ok := liveRoles[roleKey]; !ok {
			roleCreations[roleKey] = actions
		}
	}

	for roleKey, role := range liveRoles {
		if !skipDeletions {
			if _, ok := wantRoles[roleKey]; !ok {
				roleDeletions = append(roleDeletions, role.ID)
			}
		}

		roleIDs[roleKey] = role.ID
	}

	roleMembershipsAdd := make(map[string][]gidx.PrefixedID)
	roleMembershipsRemove := make(map[string][]gidx.PrefixedID)

	for roleKey, assignments := range wantAssignments {
		for memberID := range assignments {
			if _, ok := liveAssignments[roleKey]; ok {
				if _, ok := liveAssignments[roleKey][memberID]; ok {
					continue
				}
			}

			roleMembershipsAdd[roleKey] = append(roleMembershipsAdd[roleKey], memberID)
			totalRoleAssign++
		}
	}

	if !skipDeletions {
		for roleKey, assignments := range liveAssignments {
			for memberID := range assignments {
				if _, ok := wantAssignments[roleKey]; ok {
					if _, ok := wantAssignments[roleKey][memberID]; ok {
						continue
					}
				}

				roleMembershipsRemove[roleKey] = append(roleMembershipsRemove[roleKey], memberID)
				totalRoleUnassign++
			}
		}
	}

	totalRoleCreate += len(roleCreations)
	totalRoleDelete += len(roleDeletions)

	rlogger.Debugw("processing memberships",
		"role.create", totalRoleCreate,
		"role.delete", totalRoleDelete,
		"role.assign", totalRoleAssign,
		"role.unassign", totalRoleUnassign,
	)

	var (
		rolesCreated, rolesDeleted         int
		roleAssignments, roleUnassignments int
	)

	for roleKey, actions := range roleCreations {
		roleID, err := s.perms.CreateRole(ctx, relationships.Resource.PrefixedID(), actions)
		if err != nil {
			rlogger.Errorw("error creating role", "actions", actions, "error", err)

			continue
		}

		roleIDs[roleKey] = roleID
		rolesCreated++
	}

	for _, roleID := range roleDeletions {
		if err := s.perms.DeleteRole(ctx, roleID); err != nil {
			rlogger.Errorw("error deleting role", "role.id", roleID, "error", err)

			continue
		}

		rolesDeleted++
	}

	for roleKey, members := range roleMembershipsAdd {
		roleID, ok := roleIDs[roleKey]
		if !ok {
			rlogger.Errorw("role id not found for role actions key", "role_actions_key", roleKey, "members", len(members))

			continue
		}

		for _, memberID := range members {
			if err := s.perms.AssignRole(ctx, roleID, memberID); err != nil {
				rlogger.Errorw("error assigning member to role", "role.id", roleID, "member.id", memberID, "error", err)

				continue
			}

			roleAssignments++
		}
	}

	for roleKey, members := range roleMembershipsRemove {
		roleID, ok := roleIDs[roleKey]
		if !ok {
			rlogger.Errorw("role id not found for role actions key", "role_actions_key", roleKey, "members", len(members))

			continue
		}

		for _, memberID := range members {
			if err := s.perms.UnassignRole(ctx, roleID, memberID); err != nil {
				rlogger.Errorw("error removing member from role", "role.id", roleID, "member.id", memberID, "error", err)

				continue
			}

			roleUnassignments++
		}
	}

	rlogger.Debugw("memberships processed",
		"role.create", rolesCreated,
		"role.delete", rolesDeleted,
		"role.assign", roleAssignments,
		"role.unassign", roleUnassignments,
	)

	return rolesCreated + rolesDeleted, roleAssignments + roleUnassignments
}

// mapResourceWants processes the provided memberships and returns two maps.
// A Role Key is computed based on a sorted slice of actions for each role.
// The first map is of Role Key -> list of actions
// The second map is of Role Key -> Member ID -> true
func (s *service) mapResourceWants(memberships []ResourceMemberships) (map[string][]string, map[string]map[gidx.PrefixedID]bool) {
	roleActionsKey := make(map[string]string)

	for role, actions := range s.roles {
		roleActionsKey[role] = strings.Join(actions, "|")
	}

	wantRoles := make(map[string][]string)
	wantAssignments := make(map[string]map[gidx.PrefixedID]bool)

	for _, membership := range memberships {
		roleKey := roleActionsKey[membership.Role]

		if _, ok := wantRoles[roleKey]; !ok {
			wantRoles[roleKey] = s.roles[membership.Role]
			wantAssignments[roleKey] = make(map[gidx.PrefixedID]bool)
		}

		wantAssignments[roleKey][membership.Member.PrefixedID()] = true
	}

	return wantRoles, wantAssignments
}

// mapResourceDetails fetches the provided ResourceID's live state and returns two maps and an error.
// A Role Key is computed based on a sorted slice of actions for each role.
// The first map is of Role Key -> Permissions Resource Role
// The second map is of Role Key -> Member ID -> true
func (s *service) mapResourceDetails(ctx context.Context, resourceID gidx.PrefixedID) (map[string]permissions.ResourceRole, map[string]map[gidx.PrefixedID]bool, error) {
	roles := make(map[string]permissions.ResourceRole)
	assignments := make(map[string]map[gidx.PrefixedID]bool)

	liveRoles, err := s.perms.ListResourceRoles(ctx, resourceID)
	if err != nil {
		return nil, nil, err
	}

	for _, role := range liveRoles {
		slices.Sort(role.Actions)

		roleKey := strings.Join(role.Actions, "|")
		roles[roleKey] = role

		liveAssignments, err := s.perms.ListRoleAssignments(ctx, role.ID)
		if err != nil {
			return nil, nil, err
		}

		assignments[roleKey] = make(map[gidx.PrefixedID]bool)

		for _, assignment := range liveAssignments {
			assignments[roleKey][assignment] = true
		}
	}

	return roles, assignments, nil
}