package oci

import (
	"context"
	"fmt"
	"time"

	"github.com/oracle/oci-go-sdk/v65/core"
)

// 本文件实现 VCN 的级联删除：OCI 要求 VCN 删除前先清空其子网、网关、
// 非默认路由表 / 安全列表 / DHCP 选项，顺序参照控制台删除向导。
// 子网仍被 VNIC 占用（实例未终止）时 OCI 返回 409 IncorrectState，
// 该错误经 api 层提炼后提示用户先终止实例，不在此做实例级清理。

// deleteVcnCascade 依次清理关联资源后删除 VCN。
func deleteVcnCascade(ctx context.Context, vn core.VirtualNetworkClient, vcnID string) error {
	vcnResp, err := vn.GetVcn(ctx, core.GetVcnRequest{VcnId: &vcnID})
	if err != nil {
		return fmt.Errorf("get vcn %s: %w", vcnID, err)
	}
	comp := deref(vcnResp.CompartmentId)
	if err := deleteVcnSubnets(ctx, vn, comp, vcnID); err != nil {
		return err
	}
	if err := clearVcnRouteTables(ctx, vn, comp, vcnID, deref(vcnResp.DefaultRouteTableId)); err != nil {
		return err
	}
	if err := deleteVcnGateways(ctx, vn, comp, vcnID); err != nil {
		return err
	}
	if err := deleteVcnSecondaries(ctx, vn, comp, vcnID, vcnResp.Vcn); err != nil {
		return err
	}
	if _, err := vn.DeleteVcn(ctx, core.DeleteVcnRequest{VcnId: &vcnID}); err != nil {
		return fmt.Errorf("delete vcn %s: %w", vcnID, err)
	}
	return nil
}

// deleteVcnSubnets 删除 VCN 下全部子网并等待终止完成。
func deleteVcnSubnets(ctx context.Context, vn core.VirtualNetworkClient, compartmentID, vcnID string) error {
	resp, err := vn.ListSubnets(ctx, core.ListSubnetsRequest{CompartmentId: &compartmentID, VcnId: &vcnID})
	if err != nil {
		return fmt.Errorf("list subnets: %w", err)
	}
	for _, s := range resp.Items {
		if s.LifecycleState == core.SubnetLifecycleStateTerminated ||
			s.LifecycleState == core.SubnetLifecycleStateTerminating {
			continue
		}
		if _, err := vn.DeleteSubnet(ctx, core.DeleteSubnetRequest{SubnetId: s.Id}); err != nil {
			return fmt.Errorf("delete subnet %s: %w", deref(s.DisplayName), err)
		}
	}
	return waitSubnetsGone(ctx, vn, compartmentID, vcnID)
}

// waitSubnetsGone 轮询等待 VCN 下子网全部终止，超时 60 秒。
func waitSubnetsGone(ctx context.Context, vn core.VirtualNetworkClient, compartmentID, vcnID string) error {
	for i := 0; i < 30; i++ {
		resp, err := vn.ListSubnets(ctx, core.ListSubnetsRequest{CompartmentId: &compartmentID, VcnId: &vcnID})
		if err != nil {
			return fmt.Errorf("wait subnets terminated: %w", err)
		}
		alive := 0
		for _, s := range resp.Items {
			if s.LifecycleState != core.SubnetLifecycleStateTerminated {
				alive++
			}
		}
		if alive == 0 {
			return nil
		}
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-time.After(2 * time.Second):
		}
	}
	return fmt.Errorf("wait subnets terminated: timeout after 60s")
}

// clearVcnRouteTables 清空所有路由表规则（解除对网关的引用）并删除非默认路由表。
func clearVcnRouteTables(ctx context.Context, vn core.VirtualNetworkClient, compartmentID, vcnID, defaultRtID string) error {
	resp, err := vn.ListRouteTables(ctx, core.ListRouteTablesRequest{CompartmentId: &compartmentID, VcnId: &vcnID})
	if err != nil {
		return fmt.Errorf("list route tables: %w", err)
	}
	for _, rt := range resp.Items {
		if len(rt.RouteRules) > 0 {
			if _, err := vn.UpdateRouteTable(ctx, core.UpdateRouteTableRequest{
				RtId:                    rt.Id,
				UpdateRouteTableDetails: core.UpdateRouteTableDetails{RouteRules: []core.RouteRule{}},
			}); err != nil {
				return fmt.Errorf("clear route table %s: %w", deref(rt.DisplayName), err)
			}
		}
		if deref(rt.Id) != defaultRtID {
			if _, err := vn.DeleteRouteTable(ctx, core.DeleteRouteTableRequest{RtId: rt.Id}); err != nil {
				return fmt.Errorf("delete route table %s: %w", deref(rt.DisplayName), err)
			}
		}
	}
	return nil
}

// deleteVcnGateways 删除 VCN 下的互联网 / NAT / 服务网关。
func deleteVcnGateways(ctx context.Context, vn core.VirtualNetworkClient, compartmentID, vcnID string) error {
	if err := deleteInternetGateways(ctx, vn, compartmentID, vcnID); err != nil {
		return err
	}
	if err := deleteNatGateways(ctx, vn, compartmentID, vcnID); err != nil {
		return err
	}
	return deleteServiceGateways(ctx, vn, compartmentID, vcnID)
}

func deleteInternetGateways(ctx context.Context, vn core.VirtualNetworkClient, compartmentID, vcnID string) error {
	resp, err := vn.ListInternetGateways(ctx, core.ListInternetGatewaysRequest{CompartmentId: &compartmentID, VcnId: &vcnID})
	if err != nil {
		return fmt.Errorf("list internet gateways: %w", err)
	}
	for _, g := range resp.Items {
		if _, err := vn.DeleteInternetGateway(ctx, core.DeleteInternetGatewayRequest{IgId: g.Id}); err != nil {
			return fmt.Errorf("delete internet gateway %s: %w", deref(g.DisplayName), err)
		}
	}
	return nil
}

func deleteNatGateways(ctx context.Context, vn core.VirtualNetworkClient, compartmentID, vcnID string) error {
	resp, err := vn.ListNatGateways(ctx, core.ListNatGatewaysRequest{CompartmentId: &compartmentID, VcnId: &vcnID})
	if err != nil {
		return fmt.Errorf("list nat gateways: %w", err)
	}
	for _, g := range resp.Items {
		if _, err := vn.DeleteNatGateway(ctx, core.DeleteNatGatewayRequest{NatGatewayId: g.Id}); err != nil {
			return fmt.Errorf("delete nat gateway %s: %w", deref(g.DisplayName), err)
		}
	}
	return nil
}

func deleteServiceGateways(ctx context.Context, vn core.VirtualNetworkClient, compartmentID, vcnID string) error {
	resp, err := vn.ListServiceGateways(ctx, core.ListServiceGatewaysRequest{CompartmentId: &compartmentID, VcnId: &vcnID})
	if err != nil {
		return fmt.Errorf("list service gateways: %w", err)
	}
	for _, g := range resp.Items {
		if _, err := vn.DeleteServiceGateway(ctx, core.DeleteServiceGatewayRequest{ServiceGatewayId: g.Id}); err != nil {
			return fmt.Errorf("delete service gateway %s: %w", deref(g.DisplayName), err)
		}
	}
	return nil
}

// deleteVcnSecondaries 删除非默认安全列表与非默认 DHCP 选项。
func deleteVcnSecondaries(ctx context.Context, vn core.VirtualNetworkClient, compartmentID, vcnID string, vcn core.Vcn) error {
	slResp, err := vn.ListSecurityLists(ctx, core.ListSecurityListsRequest{CompartmentId: &compartmentID, VcnId: &vcnID})
	if err != nil {
		return fmt.Errorf("list security lists: %w", err)
	}
	for _, sl := range slResp.Items {
		if deref(sl.Id) == deref(vcn.DefaultSecurityListId) {
			continue
		}
		if _, err := vn.DeleteSecurityList(ctx, core.DeleteSecurityListRequest{SecurityListId: sl.Id}); err != nil {
			return fmt.Errorf("delete security list %s: %w", deref(sl.DisplayName), err)
		}
	}
	dhResp, err := vn.ListDhcpOptions(ctx, core.ListDhcpOptionsRequest{CompartmentId: &compartmentID, VcnId: &vcnID})
	if err != nil {
		return fmt.Errorf("list dhcp options: %w", err)
	}
	for _, d := range dhResp.Items {
		if deref(d.Id) == deref(vcn.DefaultDhcpOptionsId) {
			continue
		}
		if _, err := vn.DeleteDhcpOptions(ctx, core.DeleteDhcpOptionsRequest{DhcpId: d.Id}); err != nil {
			return fmt.Errorf("delete dhcp options %s: %w", deref(d.DisplayName), err)
		}
	}
	return nil
}