// Copyright (c) 2022 Tigera, Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package commands

import (
	"encoding/json"
	"fmt"
	"io"
	"os"
	"strconv"
	"strings"

	log "github.com/sirupsen/logrus"
	"github.com/spf13/cobra"

	"github.com/projectcalico/calico/felix/bpf"
	"github.com/projectcalico/calico/felix/bpf/asm"
	"github.com/projectcalico/calico/felix/bpf/counters"
	"github.com/projectcalico/calico/felix/bpf/hook"
	"github.com/projectcalico/calico/felix/proto"
)

// policyCmd represents the counters command
var policyCmd = &cobra.Command{
	Use:   "policy",
	Short: "Dump policy attached to interface",
}

func init() {
	policyCmd.AddCommand(policyDumpCmd)
	policyDumpCmd.Flags().BoolP("asm", "a", false, "Includes eBPF assembler code of the policy program")
	rootCmd.AddCommand(policyCmd)
}

var policyDumpCmd = &cobra.Command{
	Use: "dump <interface> <hook>\n" +
		"\n\thook - can be 'ingress', 'egress', 'xdp' or 'all'.",
	Short: "dumps policy",
	Run: func(cmd *cobra.Command, args []string) {
		iface, h, err := parseArgs(args)
		if err != nil {
			log.WithError(err).Error("Failed to dump policy info.")
			return
		}
		var hooks []hook.Hook
		switch h {
		case "all":
			hooks = hook.All
		case "egress":
			hooks = []hook.Hook{hook.Egress}
		case "ingress":
			hooks = []hook.Hook{hook.Ingress}
		case "xdp":
			hooks = []hook.Hook{hook.XDP}
		}

		rmap := counters.PolicyMap()
		m, err := counters.LoadPolicyMap(rmap)
		if err != nil {
			log.WithError(err).Error("error loading rule counters map.")
			return
		}

		for _, dir := range hooks {
			err := dumpPolicyInfo(cmd, iface, dir, m)
			if err != nil {
				log.WithError(err).Error("Failed to dump policy info.")
			}
		}
	},
}

func parseArgs(args []string) (string, string, error) {
	lenArgs := len(args)
	if lenArgs != 2 {
		return "", "", fmt.Errorf("Invalid number of arguments: %d", lenArgs)
	}
	hookArg := args[1]
	if hook.StringToHook(hookArg) == hook.Bad && hookArg != "all" {
		return "", "", fmt.Errorf("Invalid argument: '%s'", hookArg)
	}
	return args[0], args[1], nil
}

func printInsn(cmd *cobra.Command, insn asm.Insn) {
	cmd.Printf("%-6s", "")
	for _, value := range insn.Instruction {
		cmd.Printf("%02x", value)
	}
	cmd.Printf(" %-80v", insn)
	if insn.Annotation != "" {
		cmd.Printf("%s", insn.Annotation)
	}
	cmd.Println()
}

func getRuleMatchID(comment string) uint64 {
	matchID := strings.Split(comment, "Rule MatchID:")[1]
	matchID = strings.Trim(matchID, " ")
	id, err := strconv.ParseUint(matchID, 0, 64)
	if err != nil {
		return 0
	}
	return id
}

func dumpPolicyInfo(cmd *cobra.Command, iface string, h hook.Hook, m counters.PolicyMapMem) error {
	verboseFlag := cmd.Flag("asm").Value.String()
	verboseFlagSet, _ := strconv.ParseBool(verboseFlag)

	var policyDbg bpf.PolicyDebugInfo
	family := proto.IPVersion_IPV4
	if ipv6 != nil && *ipv6 {
		family = proto.IPVersion_IPV6
	}
	filename := bpf.PolicyDebugJSONFileName(iface, h.String(), family)
	_, err := os.Stat(filename)
	if err != nil {
		return err
	}

	jsonFile, err := os.Open(filename)
	if err != nil {
		return err
	}

	byteValue, _ := io.ReadAll(jsonFile)
	dec := json.NewDecoder(strings.NewReader(string(byteValue)))
	err = dec.Decode(&policyDbg)
	if err != nil {
		return err
	}

	cmd.Printf("IfaceName: %s\n", policyDbg.IfaceName)
	cmd.Printf("Hook: %s\n", policyDbg.Hook)
	cmd.Printf("Error: %s\n", policyDbg.Error)
	cmd.Println("Policy Info:")

	for _, insn := range policyDbg.PolicyInfo {
		for _, comment := range insn.Comments {
			if strings.Contains(comment, "Rule MatchID") {
				matchId := getRuleMatchID(comment)
				cmd.Printf("// count = %d\n", m[matchId])
			} else if verboseFlagSet || strings.Contains(comment, "Start of policy") || strings.Contains(comment, "Start of rule") {
				cmd.Printf("// %s\n", comment)
			}
		}
		for _, label := range insn.Labels {
			if verboseFlagSet {
				cmd.Printf("%s:\n", label)
			}
		}
		if verboseFlagSet {
			printInsn(cmd, insn)
		}
	}
	return nil
}
