// Copyright Istio Authors
//
// 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 configdump

import (
	"encoding/json"
	"fmt"
	"io"
	"text/tabwriter"

	"sigs.k8s.io/yaml"

	"istio.io/istio/pkg/maps"
)

// TargetWorkload identifies a specific workload pod that was targeted by the user.
// When set, commands should filter output to only show data relevant to this workload.
type TargetWorkload struct {
	Name      string
	Namespace string
}

// ConfigWriter is a writer for processing responses from the Ztunnel Admin config_dump endpoint
type ConfigWriter struct {
	Stdout      io.Writer
	ztunnelDump *ZtunnelDump
	FullDump    []byte
	// TargetWorkload is set when the user targeted a workload pod (not a ztunnel pod).
	// Commands use this to filter output to only the targeted workload.
	TargetWorkload *TargetWorkload
}

type rawDump struct {
	Services      json.RawMessage          `json:"services"`
	Workloads     json.RawMessage          `json:"workloads"`
	Policies      json.RawMessage          `json:"policies"`
	Certificates  json.RawMessage          `json:"certificates"`
	WorkloadState map[string]WorkloadState `json:"workloadstate"`
}

// Prime loads the config dump into the writer ready for printing
func (c *ConfigWriter) Prime(b []byte) error {
	zDump := &ZtunnelDump{}
	rawDump := &rawDump{}
	// TODO(fisherxu): migrate this to jsonpb when issue fixed in golang
	// Issue to track -> https://github.com/golang/protobuf/issues/632
	err := json.Unmarshal(b, rawDump)
	if err != nil {
		return fmt.Errorf("error unmarshalling config dump response from ztunnel: %v", err)
	}
	// ensure that data gets unmarshalled into the right data type
	if err := unmarshalListOrMap(rawDump.Services, &zDump.Services); err != nil {
		return err
	}
	if err := unmarshalListOrMap(rawDump.Workloads, &zDump.Workloads); err != nil {
		return err
	}
	if err := unmarshalListOrMap(rawDump.Certificates, &zDump.Certificates); err != nil {
		return err
	}
	if err := unmarshalListOrMap(rawDump.Policies, &zDump.Policies); err != nil {
		return err
	}
	zDump.WorkloadState = rawDump.WorkloadState
	c.ztunnelDump = zDump
	return nil
}

func unmarshalListOrMap[T any](input json.RawMessage, i *[]T) error {
	if len(input) == 0 {
		return nil
	}
	if input[0] == '[' {
		return json.Unmarshal(input, i)
	}
	m := make(map[string]T)
	if err := json.Unmarshal(input, &m); err != nil {
		return err
	}
	*i = maps.Values(m)
	return nil
}

// PrintBootstrapDump prints just the bootstrap config dump to the ConfigWriter stdout
func (c *ConfigWriter) PrintBootstrapDump(outputFormat string) error {
	// TODO
	return nil
}

func (c *ConfigWriter) printHeaders(summary string, withHeaders bool) {
	if withHeaders {
		_, _ = c.Stdout.Write([]byte("------ "))
		_, _ = c.Stdout.Write([]byte(summary))
		_, _ = c.Stdout.Write([]byte(" ------\n\n"))
	}
}

func (c *ConfigWriter) PrintFullSummary(withHeaders bool) error {
	_, _ = c.Stdout.Write([]byte("\n"))
	c.printHeaders("WORKLOAD INFO", withHeaders)
	if err := c.PrintWorkloadSummary(WorkloadFilter{}); err != nil {
		return err
	}
	_, _ = c.Stdout.Write([]byte("\n"))
	c.printHeaders("SERVICE INFO", withHeaders)
	if err := c.PrintServiceSummary(ServiceFilter{}); err != nil {
		return err
	}
	_, _ = c.Stdout.Write([]byte("\n"))
	c.printHeaders("POLICY INFO", withHeaders)
	if err := c.PrintPolicySummary(PolicyFilter{}); err != nil {
		return err
	}
	_, _ = c.Stdout.Write([]byte("\n"))
	c.printHeaders("SECRET INFO", withHeaders)
	if err := c.PrintSecretSummary(); err != nil {
		return err
	}
	_, _ = c.Stdout.Write([]byte("\n"))
	c.printHeaders("CONNECTIONS INFO", withHeaders)
	if err := c.PrintConnectionsSummary(ConnectionsFilter{}); err != nil {
		return err
	}
	return nil
}

func (c *ConfigWriter) PrintFullDump(outputFormat string) error {
	out := c.FullDump
	if outputFormat == "yaml" {
		var err error
		out, err = yaml.JSONToYAML(out)
		if err != nil {
			return err
		}
	}
	fmt.Fprintln(c.Stdout, string(out))
	return nil
}

// PrintVersionSummary prints version information for Istio and Ztunnel from the config dump
func (c *ConfigWriter) PrintVersionSummary() error {
	// TODO
	return nil
}

// PrintPodRootCAFromDynamicSecretDump prints just pod's root ca from dynamic secret config dump to the ConfigWriter stdout
func (c *ConfigWriter) PrintPodRootCAFromDynamicSecretDump() (string, error) {
	// TODO
	return "", nil
}

func (c *ConfigWriter) tabwriter() *tabwriter.Writer {
	w := new(tabwriter.Writer).Init(c.Stdout, 0, 8, 1, ' ', 0)
	return w
}
